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Human Cannabinoid Pharmacokinetics

A multitude of roles for the endogenous cannabinoid system has been proposed by recent research efforts. A large number of endogenous cannabinoid neurotransmitters or endocannabinoids have been identified, and the CB-1 and CB-2 cannabinoid receptors have been characterized. The presence of other receptors, transporters, and enzymes responsible for the synthesis or metabolism of endocannabinoids are becoming known at an extraordinary pace. The complex functions of this novel system have created multiple new targets for pharmacotherapies. Research has focused on separating the behavioral psychoactive effects of cannabinoid agonists from therapeutic effects. These efforts have been largely unsuccessful. Another strategy centers on changing the pharmacokinetics of drug delivery to maximize therapeutic effect and minimize cognitive and subjective drug effects. Development of oral, rectal, and transdermal medications of synthetic Δ 9 -tetrahydrocannabinol (THC) 1 ) are examples of this type of approach. Additionally, the potential therapeutic benefits of administering unique combinations of cannabinoids and other chemicals present in the plant Cannabis sativa is being investigated by the oromucosal route. There also is strong interest in medications based on antagonizing endocannabinoid action.

We have shown that the cardiovascular and subjective effects of cannabis are blocked by rimonabant, the first CB-1 cannabinoid-receptor antagonist, documenting that CB-1 receptors mediate these effects of smoked cannabis in humans. It is clear that the endogenous cannabinoid system plays a critical role in physiological and behavioral processes, and extensive research effort is being devoted to the biology, chemistry, pharmacology, and toxicology of cannabinoids.

Cannabis is one of the oldest and most commonly abused drugs in the world, and its use is associated with pathological and behavioral toxicity. Thus, it is important to understand cannabinoid pharmacokinetics and the disposition of cannabinoids into biological fluids and tissues. Understanding the pharmacokinetics of a drug is essential to understanding the onset, magnitude, and duration of its pharmacodynamic effects, maximizing therapeutic and minimizing negative side effects.

Cannabinoid pharmacokinetics encompasses absorption after diverse routes of administration and from different drug formulations, analyte distribution throughout the body, metabolism by the liver and extra-hepatic tissues, and elimination in the feces, urine, sweat, oral fluid, and hair. Pharmacokinetic processes are dynamic, may change over time, and may be affected by the frequency and magnitude of drug exposure. The many contributions to our understanding of cannabinoid pharmacokinetics from the 1970s and 1980s are reviewed, and the findings of recent research expanding upon this knowledge are detailed. Cannabinoid pharmacokinetics research is challenging due to low analyte concentrations, rapid and extensive metabolism, and physico-chemical characteristics hindering the separation of drugs of interest from biological matrices and from each other. Drug recovery is reduced due to adsorption of compounds of interest to multiple surfaces. Much of the early cannabinoid data are based on radiolabeled cannabinoids yielding highly sensitive, but less specific, measurement of individual cannabinoid analytes. New extraction techniques and mass-spectrometric (MS) developments now permit highly sensitive and specific measurement of cannabinoids in a wide variety of biological matrices, improving our ability to characterize cannabinoid pharmacokinetics.

Cannabis sativa contains over 421 different chemical compounds, including over 60 cannabinoids [1-3]. Cannabinoid plant chemistry is far more complex than that of pure THC, and different effects may be expected due to the presence of additional cannabinoids and other chemicals. Eighteen different classes of chemicals, including nitrogenous compounds, amino acids, hydrocarbons, carbohydrates, terpenes, and simple and fatty acids, contribute to the known pharmacological and toxicological properties of cannabis. THC is usually present in Cannabis plant material as a mixture of monocarboxylic acids, which readily and efficiently decarboxylate upon heating. THC decomposes when exposed to air, heat, or light; exposure to acid can oxidize the compound to cannabinol (CBN), a much less-potent cannabinoid. In addition, cannabis plants dried in the sun release variable amounts of THC through decarboxylation. During smoking, more than 2,000 compounds may be produced by pyrolysis. The pharmacokinetics of THC, the primary psychoactive component of cannabis, its metabolites ‘11-hydroxytetrahydrocannabinol’ (11-OH-THC) and ‘11-nor-9-carboxy-tetrahydrocannabinol’ (THC-COOH)] 2 ), and another cannabinoid present in high concentration, cannabidiol (CBD), a non-psychoactive agent with an interesting array of potential therapeutic indications, are included. Mechoulam et al. elucidated the structure of THC in 1964, enabling studies of the drug’s pharmacokinetics [4]. THC, containing no N-atom, but with two stereogenic centers in a trans configuration, has been described by two different atom-numbering systems, either the dibenzopyran (or Δ 9 ) or the monoterpene (or Δ 1 ) system. In this review, the dibenzopyran (Δ 9 ) system is employed.

2. Pharmacokinetics of Cannabinoids

2.1. Absorption

2.1.1. Smoking

Route of drug administration and drug formulation determine the rate of drug absorption. Smoking, the principal route of cannabis administration, provides a rapid and efficient method of drug delivery from the lungs to the brain, contributing to its abuse potential. Intense pleasurable and strongly reinforcing effects may be produced due to almost immediate drug exposure to the central nervous system (CNS). Slightly lower peak THC concentrations are achieved after smoking as compared to intravenous administration [5]. Bioavailability following the smoking route was reported as 2−56%, due in part to intra- and inter-subject variability in smoking dynamics, which contributes to uncertainty in dose delivery [6-9]. The number, duration, and spacing of puffs, hold time, and inhalation volume, or smoking topography, greatly influences the degree of drug exposure [10-12]. Expectation of drug reward also may affect smoking dynamics. Cami et al. noted that subjects were able to change their method of smoking hashish cigarettes to obtain higher plasma concentrations of THC, when they expected to receive active drug in comparison to placebo cigarettes [13].

A continuous blood-withdrawal pump, collecting blood at a rate of 5 ml/min, enabled capture of the rapid THC absorption phase during smoking for the first time. Formation of 11-OH-THC and THC-COOH was slower, and peak concentrations were much lower [14]. The disposition of THC and its metabolites were followed for a period of 7 d after smoking a single placebo, and cigarettes containing 1.75% or 3.55% of THC. The mean (±S.D.) THC concentrations were 7.0±8.1 ng/ml and 18.1±12.0 ng/ml upon single inhalation of the low-dose (1.75% THC, ca. 16 mg) or the high-dose (3.55% THC, ca. 34 mg) cigarette, respectively, as determined by gas-chromatography/mass spectrometry (GC/MS) [14]. THC, detected in plasma immediately after the first cigarette puff ( Fig. 1 ), was accompanied by the onset of cannabinoid effects [15]. Concentrations increased rapidly, reaching mean peaks of 84.3 ng/ml (range 50−129) and 162.2 ng/ml (range 76−267) for the above two cigarettes, respectively. Peak concentrations occurred at 9.0 min, prior to initiation of the last puff sequence at 9.8 min.

Mean (N=6) plasma concentrations of THC, 11-OH-THC, and THC-COOH during smoking of a single cannabis cigarette containing 3.55% of THC. Arrows (↓) indicate one inhalation or puff on the cannabis cigarette. Reprinted and adapted with permission by Springer-Verlag, ‘Handbook of Experimental Pharmacology’, 2005, p. 660, Fig. 1.

Despite a computer-paced smoking procedure that controlled the number of puffs, length of inhalation, hold time, and time between puffs, there were large inter-subject differences in plasma THC concentrations due to differences in the depth of inhalation, as participants titrated their THC dose ( Fig. 2 ). The mean THC concentrations were ca. 60 and 20% of the peak concentrations 15 and 30 min post smoking, respectively. Within 2 h, plasma THC concentrations were ≤ 5 ng/ml. THC Detection windows (GC/MS detection limit 0.5 ng/ml) varied from 3 to 12 h after smoking the low-dose (1.75% THC) cannabis cigarette, and from 6 to 27 h in the case of the high-dose (3.55% THC) cigarette.

Time-dependent THC concentrations for six individuals (subjects B, C, and E–H) following smoking of a single cannabis cigarette containing 3.55% of THC. Reprinted and adapted with permission by Journal of Analytical Toxicology, p. 280 in [14], Fig. 1 .

Similar mean maximum THC concentrations were reported in specimens collected immediately after cannabis smoking was completed. The mean peak THC concentrations were 94.3, 107.4, and 155.1 ng/ml after smoking single cigarettes of 1.32, 1.97, or 2.54% THC, respectively [16]. Other reported peak THC concentrations ranged between 45.6 and 187.8 ng/ml following smoking of a cigarette containing 1% of THC [17], and 33−118 ng/ml 3 min after ad libitum smoking of a cigarette containing ca. 2% of THC [5]. The smoking route is preferred by many cannabis users because of its rapid drug delivery and resultant fast onset of effects, but also for the ability to titrate dose to the desired degree of effect. In our controlled smoked-cannabis experiments described above, the individual with the lowest peak plasma concentration had the greatest cardiovascular response [15].

The average concentrations in more than 30,000 cannabis preparations confiscated in the U.S. between 1980 and 1997 were 3.1% THC and only 0.3% CBD [18]. However, cannabis-based medicine extracts and clinical-grade cannabis contain high quantities of CBD, which frequently equal the percentage of THC [19]. CBD may modify the effects of THC and reportedly may inhibit cytochrome P450 (CYP 450)-mediated conversion of THC to 11-OH-THC [20][21], although results are not always consistent across studies. The formation of THC from CBD neither occurs by heat during smoking [22] nor by human metabolism.

2.1.2. Oral

There are fewer studies on the disposition of THC and its metabolites after oral administration of cannabis as compared to the smoked route. THC is readily absorbed due to its high octanol/water partition coefficient (P), estimated to be between 6,000 and over 9 × 10 6 , depending on the method of determination [23]. The advantages of cannabinoid smoking are offset by the harmful effects of cannabinoid smoke; hence smoking is generally not recommended for therapeutic applications. Synthetic THC, i.e., dronabinol (Marinol®) preparations, are usually taken orally, but may also be administered rectally. In addition, abuse of cannabis by the oral route also is common. Absorption is slower when cannabinoids are ingested, with lower, more-delayed peak THC concentrations [24][25]. Dose, route of administration, vehicle, and physiological factors such as absorption and rates of metabolism and excretion can influence drug concentrations in circulation. Perez-Reyes et al. described the efficacy of five different vehicles for oral administration of THC in gelatin capsules [26]. Glycocholate and sesame oil improved the bioavailability of oral THC; however, there was considerable variability in peak concentrations and rates of absorption, even when the drug was administered in the same vehicle. Oral THC bioavailability was reported to be 10−20% by Wall et al. [27]. Participants were dosed with either 15 mg (women) or 20 mg (men) of THC dissolved in sesame oil and contained in gelatin capsules. THC Plasma concentrations peaked ca. 4−6 h after ingestion of 15−20 mg of THC in sesame oil. A percentage of the THC was radiolabeled; however, investigators were unable to differentiate labeled THC from its labeled metabolites. Thus, THC concentrations were overestimated.

Possibly a more accurate assessment of oral bioavailability of THC in plasma samples was reported by Ohlsson et al., based on GC/MS experiments [5]. The peak THC concentrations ranged from 4.4 to 11 ng/ml, occurring 1−5 h following ingestion of 20 mg of THC in a chocolate cookie; the oral bioavailability was estimated to be 6%. Slow rates of absorption and low THC concentrations occur after oral administration of THC or cannabis. Several factors may account for the low oral bioavailability of 4−20% (as compared to intravenous drug administration), including variable absorption, degradation of drug in the stomach, and significant first-pass metabolism to active 11-OH-THC and inactive metabolites in the liver.

Currently, synthetic THC (Marinol®) is approved in the U.S.A. for reduction of nausea and vomiting in cancer chemotherapy, and to increase appetite in HIV-wasting disease. Potential new indications include the reduction of spasticity, analgesia, and as an agonist-replacement pharmacotherapy for cannabis dependence. Thus, the pharmacokinetics of oral THC is of great importance to the successful application of new therapeutic approaches. In a study of the plasma concentrations of THC, 11-OH-THC, and THC-COOH in 17 volunteers upon intake of a single Marinol® capsule (10 mg of THC), mean peak concentrations of 3.8 ng/ml of THC (range 1.1−12.7 ng/ml), 3.4 ng/ml of 11-OH-THC (range 1.2−5.6 ng/ml), and 26 ng/ml of THC-COOH (range 14−46 ng/ml) were found 1−2 h after ingestion [28]. Similar THC and 11-OH-THC concentrations were observed with consistently higher THC-COOH concentrations. Interestingly, two THC peaks frequently were observed due to enterohepatic circulation. Onset is delayed, peak concentrations are lower, and duration of pharmacodynamic effects generally are extended with a delayed return to baseline, when THC is administered by the oral as compared to the smoked route [29][30].

In addition, THC-containing foods, i.e., hemp oil, beer, and other products, are commercially available for oral consumption. Hemp oil is produced from cannabis seed, and is an excellent source of essential amino acids and ω-linoleic and linolenic fatty acids. The THC content depends upon the effectiveness of cannabis-seed-cleaning and oil-filtration processes. Hemp oil with THC contents ≥ 300 and 1,500 mg/g were available in the U.S.A. and in Europe, respectively. Currently, the THC concentrations of hemp oil in the U.S.A. are low, reflecting the efforts of manufacturers to reduce the amount of THC in hemp-oil products.

In a recent, controlled cannabinoid-administration study of THC-containing hemp oils and dronabinol, the pharmacokinetics and pharmacodynamics of oral THC were evaluated. Up to 14.8 mg of THC was ingested by six volunteers each day in three divided doses with meals for five consecutive days [31][32]. There was a 10-d washout phase between each of the five dosing sessions. THC was quantified in plasma by solid-phase extraction, followed by GC/MS (positive-mode, chemical-ionization) analysis. THC and 11-OH-THC were rarely detected in plasma following the two lowest doses (0.39 and 0.47 mg/d of THC), while, as shown in Fig. 3 , peak plasma concentrations of less than 6.5 ng/ml of THC, <5.6 ng/ml of 11-OH-THC, and <43.0 ng/ml of THC-COOH were found after the two highest THC doses (7.5 and 14.8 mg/d). Interestingly, THC-COOH concentrations after THC administration at a dose of 7.5 mg/d were greater than or equal to those after intake of the high-potency hemp-oil dose (14.8 mg/d). This could be due to the formulation of dronabinol, which afforded greater protection from degradation in the stomach due to encapsulation and perhaps, improved bioavailability of THC in sesame oil, the formulation of synthetic THC or dronabinol. Plasma THC and 11-OH-THC concentrations fell below the method’s limits of quantification of 0.5 ng/ml by 25 h, while THC-COOH was still measurable for more than 50 h after the last dose of the higher-concentration hemp oils.

Plasma concentrations (N=1) over 24 h for THC, 11-OH-THC, and THC-COOH following administration of two doses (2.5 mg each) of synthetic THC (dronabinol) at 4.5 and 10.5 h. Reprinted and adapted with permission by Elsevier, p. 152 in [32], Fig. 2 .

After oral THC dosing, Nadulski et al. reported generally higher THC-COOH concentrations than those of THC almost immediately after dosing, in contrast to what is found after smoking [33]. Concentrations of 11-OH-THC also were higher than those of THC, with an extended detection window. These investigators suggest that ratios of [11-OH-THC]/[THC] >1 and >1.5 within and after 2 h after consumption, respectively, are strong indications for oral intake of THC.

Due to low bioavailability of oral THC formulations, alternative routes of drug administration, including oromucosal or sublingual dosing, vaporization of product and inhalation, and rectal administration, have been developed to improve the amount of delivered cannabinoids.

2.1.3. Oromucosal

Due to the chemical complexity of cannabis plant material compared to synthetic THC, extracts of cannabis that capture the full range of cannabinoids are being explored as therapeutic medications. Cannabis has been used as medicine for thousands of years [34][35]. Cultivation methods have been developed to reproducibly produce plants with defined THC or CBD concentrations. GW Pharmaceuticals has produced two standardized extract preparations, Tetranabinex®, which is high in THC, and Nabidiolex®, which is high in CBD. Sativex® contains equal proportions of Tetranabinex® and Nabidiolex®, and, hence, almost equal amounts of THC and CBD. THC and CBD represent approximately 70% of the product, with 5% of other cannabinoids, the remainder being terpenoids, flavonoids, sterols, alkanes, and other chemicals [36]. Clinical trials of the efficacy of these extracts are ongoing for analgesia [37][38] and spasticity, and other indications in affected patients [39]. Sativex® is administered sublingually to avoid first-pass metabolism by the liver. Sativex® is approved in Canada for the treatment of neuropathic pain associated with multiple sclerosis, and in three European countries for a number of indications.

2.1.4. Rectal

Several different suppository formulations were evaluated in monkeys to determine the matrix that maximizes bioavailability and reduces first-pass metabolism [40][41]; THC-hemisuccinate provided the highest bioavailability of 13.5%. Brenneisen et al. evaluated plasma THC concentrations in two patients who were prescribed THC-hemisuccinate suppositories or Marinol® for spasticity [42]. THC did not accumulate in the blood following 10−15 mg daily doses. THC concentrations peaked within 1−8 h after oral administration, and ranged between 2.1 to 16.9 ng/ml. Rectal administration of 2.5−5 mg of THC produced maximum plasma concentrations of 1.1−4.1 ng/ml within 2−8 h. The bioavailability of the rectal route was approximately twice that of the oral route due to higher absorption and lower first-pass metabolism.

2.1.5. Transcutaneous

Another route of cannabinoid exposure that avoids first-pass metabolism and improves THC bioavailability is topical administration [43]. Cannabinoids are highly hydrophobic, making transport across the aqueous layer of the skin the rate-limiting step in the diffusion process [44][45]. In vitro diffusion studies may underestimate in vivo transdermal flux [43]. After application of a dermal patch, mean steady-state plasma concentration of Δ 8 -THC was 4.4 ng/ml within 1.4 h, and was maintained for at least 48 h. Permeabilities of CBD and CBN were found to be 10-fold higher than for Δ 8 -THC. In vivo studies of transdermal drug delivery in guinea pigs noted the presence of significant amounts of plasma metabolites after topical application of THC [46]. Additional research is planned with combinations of cannabinoids in EtOH to increase drug absorption.

Transdermal delivery of cannabinoids is hoped to reduce negative side effects seen with inhalation dosing [47]. Transdermal delivery also bypasses first-pass metabolism of cannabinoids. These properties could improve the utility of transdermal cannabinoid medications. Applying a transdermal patch several hours before chemotherapy, and wearing it for several days, would be a convenient means for treating associated nausea and vomiting. Also, wearing a patch for a week to stimulate appetite could be a good alternative to twice a day oral dosing of dronabinol.

The drug-abuse potential of cannabinoid transdermal patches is expected to be low because of slow delivery of THC to the brain. However, extraction of cannabinoids from the patch for administration by a more-rapid method has not been evaluated. Diversion of fentanyl patches by drug abusers for use in such a manner has been a significant problem.

2.1.6. Intravenous

Although THC is not abused by the intravenous route, pharmacodynamic and pharmacokinetic cannabinoid research has employed this technique. Recently, D’Souza et al. administered THC intravenously to evaluate the association between cannabinoids and psychosis [48]. The double-blind, randomized, and placebo-controlled study investigated the behavioral, cognitive, and endocrine effects of 0, 2.5, and 5 mg of THC in healthy individuals with a history of cannabis exposure, but never diagnosed with a cannabis-abuse disorder. After 10 min, the plasma THC concentrations were 82±87.4 and 119.2±166.5 for intravenous doses of 2.5 and 5.0 mg, ng/ml respectively; the respective THC-COOH concentrations were 43.8±26.1 and 81.9±47 ng/ml. Some subjects withdrew from the study due to acute paranoia (1), panic (1), hypotension (2), withdrawal of consent due to dislike of THC effects (3), and other issues (2). One subject experienced a significant, acute paranoid reaction and was treated with 2 mg lorazepam. THC produced schizophrenia-like positive and negative symptoms and euphoria, and altered aspects of cognitive function. Plasma cortisol concentrations were not affected. THC produced a broad range of transient symptoms, behaviors, and cognitive deficits in healthy individuals that resembled endogenous psychoses. The investigators suggested that brain-cannabinoid-receptor function could be an important factor in the pathophysiology of psychotic disorders.

2.1.7. Cannabidiol Absorption

Cannabidiol (CBD) is a natural, non-psychoactive [49][50] constituent of Cannabis sativa, but possesses pharmacological activity, which is explored for therapeutic applications. CBD has been reported to be neuroprotective [51], analgesic [37][38][52], sedating [37][38][53][54], anti-emetic [54], anti-spasmodic [55], and anti-inflammatory [56]. In addition, it has been reported that CBD blocks anxiety produced by THC [57], and may be useful in the treatment of autoimmune diseases [53]. CBD also has been reported to decrease some of the side effects of THC [36]. These potential therapeutic applications alone warrant investigation of CBD pharmacokinetics. Further, the controversy over whether CBD alters the pharmacokinetics of THC in a clinically significant manner needs to be resolved [58][59].

Ohlsson et al. reported CBD levels of 37−61 ng/ml (n=3, mean 48.4 ng/ml) 1 h after intravenous injection of 20 mg of deuterium-labeled CBD, and of 3.0−17.8 ng/ml (n=3, mean 10.2 ng/ml) 1 h after smoking a cigarette containing 19.2 mg of deuterium-labeled CBD [60]. Average bioavailability by the smoked route was 31 13% in five subjects, with a fourfold difference in availability noted. Based on the area under the curve (AUC) for 72 h and the dose after intravenous administration, a plasma clearance of 960−1560 ml/min was calculated. Agurell et al. found 1.1−11 ng/ml of CBD 1 h after oral application of 40 mg of CBD (n=12, mean 5.5 ng/ml) in chocolate cookies [61]. Recently, Nadulski et al. reported CBD concentrations of 0.30−2.57 ng/ml (mean: 0.95 ng/ml) 1 h after oral intake of 5.4 mg of CBD [33]. CBD remained detectable for 3−4 h after administration. The authors suggest that identification and quantification of CBD could be an additional proof of cannabis exposure and could improve interpretation of THC effects considering the potential ability of CBD to modify THC effects.

When comparing sublingual administration of THC (25 mg) alone vs. THC/CBD (25 mg each) in cannabis-based medicinal extracts, no statistically significant differences in mean THC maximum concentration, half-life, or AUC for THC and 11-OHTHC were observed [62]. The only statistically significant difference was in the time of maximum THC concentration. Despite administration of equivalent amounts of THC and CBD, lower plasma concentrations of CBD were always observed. The pharmacokinetics of THC, 11-OH-THC, and CBD also were evaluated after administration of 10 mg each of THC and CBD, either via the sublingual, buccal, oromucosal, or oral routes [63]. All three analytes were detectable ca. 30 min after dosing, with higher THC than CBD concentrations. 11-OH-THC generally exceeded THC concentrations within 45 min of dosing. Mean maximum concentrations for THC, CBD, and 11-OH-THC were <5, <2, and <7 ng/ml, respectively, across all administration routes. High intra- and inter-subject variability was noted.

2.2. Distribution

THC Plasma concentrations decrease rapidly after the end of smoking due to rapid distribution into tissues and metabolism in the liver. THC is highly lipophilic and initially taken up by tissues that are highly perfused, such as the lung, heart, brain, and liver. Tracer doses of radioactive THC documented the large volume of distribution of THC and its slow elimination from body stores. In animals, after intravenous administration of labeled THC, higher levels of radioactivity were present in lung than in other tissues [64]. Studies of the distribution of THC into brain are especially important for understanding the relationships between THC dose and behavioral effects. After single intra-muscular administration of 14 C-labeled Δ 8 -THC to rats, maximal radioactivity was reached in brain after 2−4 h, representing 0.06% of the administered dose [65]. Plasma concentrations were of similar magnitude to those measured in men exposed to marihuana smoke. Kreuz and Axelrod were the first to describe the persistent and preferential retention of radiolabeled THC in neutral fat after multiple doses, in contrast to limited retention in brain [66]. The ratio of fat to brain THC concentration was approximately 21 : 1 after 7 d of consecutive exposure, and 64 : 1 after 27 d. Other investigators also found that the amount of THC retained in the brain after administration of radiolabeled THC was less than 1% of the administered dose [67][68]. With prolonged drug exposure, THC concentrates in human fat, being retained for extended periods of time [69]. It is suggested that fatty acid conjugates of THC and 11-OH-THC may be formed, increasing the stability of these compounds in fat [70].

Distribution of THC into peripheral organs and the brain was found to be similar in THC-tolerant vs. non-tolerant dogs [71]. In addition, these investigators found that tolerance to the behavioral effects of THC in pigeons was not due to decreased uptake of cannabinoids into the brain. Tolerance also was evaluated in humans. Hunt and Jones found that tolerance in humans developed during oral administration of 30 mg of THC every 4 h, for 10−12 d [72]. Few pharmacokinetic changes were noted during chronic administration, although average total metabolic clearance and initial apparent volume of distribution increased from 605 to 977 ml/min, and from 2.6 to 6.4 l/kg, respectively. Pharmacokinetic changes after chronic oral THC administration could not account for observed behavioral and physiologic tolerance, suggesting rather that tolerance was due to pharmacodynamic adaptation.

Adams and Martin studied the THC dose required to induce pharmacological effects in humans [73]. They determined that 2−22 mg of THC must be present in a cannabis cigarette to deliver 0.2−4.4 mg of THC, based on 10−25% bioavailability for smoked THC. Only 1% of this dose at peak concentration was found in the brain, indicating that only 2−44 μg of THC penetrates to the brain.

In a recent, highly interesting study, Mura et al. analyzed paired blood and brain specimens in 12 postmortem cases for THC and THC-COOH, and also for 11-OH-THC, in two regular cannabis smokers by GC/MS [74]. The THC concentrations in blood and brain ranged from <0.2 to 11.5 ng/ml, and from 0.9 to 29.9 ng/g, respectively. There was no correlation between blood and brain concentrations; brain levels were always higher than blood levels, and in three cases measurable drug concentrations remained in the brain, when no longer detectable in the blood. In two additional cases, sufficient brain tissue was available to monitor THC, 11-OH-THC, and THC-COOH concentrations in both blood and seven brain areas known to have high concentrations of cannabinoid CB-1 receptors. THC, 11-OH-THC, and THC-COOH were found in substantial concentrations in all brain areas, including locus niger, hippocampus, occipital lobe, striatum-putamen-palladium, frontal lobe, spinal cord, and corpus callosum, the order generally being THC≥THC-COOH>11-OH-THC. Blood concentrations were lower than in the two-paired brains. The authors postulate that long-lasting effects of cannabis during abstinence in heavy users may be due to residual THC and 11-OH-THC concentrations in the brain. The consequences of THC-COOH in the brain remain unknown.

Storage of THC after chronic exposure could also contribute to observed toxicities in other tissues. After single intramuscular administration of radioactive THC in rats, only 0.023% of the original THC dose was found in testis, although total radioactivity in epididymal fat was five- and eight times higher than that in the brain after 4 and 24 h, respectively [65]. After multiple injections, concentrations of THC remained low in plasma, brain, and testis, not exceeding 2−7 ng/g, but the epididymal-fat tracer concentration was 40 to 80 times higher. The authors suggest that the blood–brain and blood–testicular barriers limit storage of THC in brain and testis during acute exposure; however, during THC chronic exposure, pharmacokinetic mechanisms are insufficient to prevent accumulation of THC in tissues, with subsequent deregulation of cellular processes, including apoptosis of spermatogenic cells.

In one of the latest investigations on THC distribution in tissues, the large-white-pig model was selected due to similarities with humans in drug biotransformation, including enzymes and isoenzymes of drug biotransformation, size, feeding patterns, digestive physiology, dietary habits, kidney structure and function, pulmonary vascular bed structure, coronary-artery distribution, propensity to obesity, respiratory rates, and tidal volume [75]. THC Plasma pharmacokinetics was found to be similar to those in humans. Eight pigs received 200 mg/kg intra-jugular THC injections, and two pigs were sacrificed 30 min, 2, 6, and 24 h later. At 30 min, high THC concentrations were noted in lung, kidney, liver, and heart, with comparable elimination kinetics in kidney, heart, spleen, muscle, and lung as observed in blood. The fastest THC elimination was noted in liver, where concentrations fell below measurable levels by 6 h. Mean brain concentration was approximately twice the blood concentration at 30 min, with highest levels in the cerebellum, and occipital and frontal cortex, and lowest concentrations in the medulla oblongata. THC Concentrations decreased in brain tissue slower than in blood. The slowest THC elimination was observed for fat tissue, where THC was still present at substantial concentrations 24 h later. 11-OH-THC was only found at high concentrations in the liver. The THC-COOH level was <5 ng/g in most tissues, except in bile, where it increased for 24 h following THC injection. The authors suggest that the prolonged retention of THC in brain and fat in heavy cannabis users is responsible for the prolonged detection of THC-COOH in urine and cannabis-related flashbacks. The author of this review hypothesizes that this residual THC may also contribute to cognitive deficits noted early during abstinence in chronic cannabis users.

THC accumulation in the lung occurs because of high exposure from cannabis smoke, extensive perfusion of the lung, and high uptake of basic compounds in lung tissue. Lung tissue is readily available during postmortem analysis, and would be a good matrix for investigation of cannabis exposure.

Metabolism of THC to 11-OH-THC, THC-COOH, and other analytes also contributes to the reduction of THC in blood. Perez-Reyes et al. compared the pharmacokinetics and pharmacodynamics of tritiated THC and 11-OH-THC in 20 male volunteers [76]. Although equal doses produced equal psychoactive effects, drug effects were perceived more rapidly after exposure to 11-OH-THC than to THC. In addition, 11-OH-THC left the intravascular compartment faster than THC. These data suggest that 11-OH-THC diffuses into the brain more readily than THC does. Other possible explanations include lower plasma-protein binding of 11-OH-THC or enhanced crossing of the blood–brain barrier by the hydroxylated metabolite.

The distribution volume (Vd) of THC is large, ca. 10 l/kg, despite the fact that it is 95−99% protein-bound in plasma, primarily to lipoproteins [72][77]. Protein-binding values for THC-COOH and THC-COOH glucuronide were similar to those of THC proper (ca. 97%) [78]. More recently, with the benefit of advanced analytical techniques, the steady state Vd value of THC was estimated to be 3.4 l/kg [70]. THC-COOH was found to be far less lipophilic than the parent drug, whose partition coefficient P value at neutral pH has been measured at 6,000 (or higher), and more lipophilic than the glucuronide [78]. The fraction of THC glucuronide present in blood after different routes of administration has not been adequately resolved, but, recently, the partition coefficient of this compound indicated an unexpectedly high lipophilicity, ca. 18 at pH 7.4.

THC rapidly crosses the placenta, although concentrations were lower in canine and ovine fetal blood and tissues than in maternal plasma and tissues [79]. The metabolites 11-OH-THC and THC-COOH crossed the placenta much less efficiently [80][81]. No THC-COOH was detected in fetal plasma and tissues, indicating a lack of transfer across the placenta, and a lack of metabolism of THC in fetal monkey [80]. Blackard and Tennes reported that THC in cord blood was three to six times less than in maternal blood [82]. Transfer of THC to the fetus was greater in early pregnancy. THC also concentrates into breast milk from maternal plasma due to its high lipophilicity [83][84]. THC Concentration in breast milk was 8.4 times higher than in plasma in one woman, yielding a daily THC exposure to the infant of 0.01 to 0.1 mg/d, assuming that the mother smokes one to two cannabis cigarettes each day [84].

2.3. Metabolism

2.3.1. Hepatic Metabolism

Burstein and co-workers were the first to show that 11-OH-THC and THC-COOH are primary metabolites of THC in rabbits and rhesus monkeys [85-87]. They also documented that THC can be metabolized in the brain. Harvey et al. monitored the metabolism of THC, CBD, and CBN in mice, rats, and guinea pigs, and found extensive metabolism, but with inter-species variation [88]. Phase-I oxidation reactions of THC include allylic and aliphatic hydroxylations, oxidation of alcohols to ketones and acids, β-oxidation, and degradation of the pentyl side chain. Conjugation with glucuronic acid is a common Phase-II reaction. 11-OH-THC was the primary metabolite in all three species, followed by 8α-OH-THC in the mouse and rat, and 8β-OH-THC in guinea pig. Side-chain hydroxylation was common in all three species. THC-COOH concentrations were higher in the mouse and rat, while THC-COOH glucuronide concentrations predominated in the guinea pig. THC Concentrations accumulated in the liver, lung, heart, and spleen.

Hydroxylation of THC at C(9) by the hepatic CYP 450 enzyme system leads to production of the equipotent metabolite 11-OH-THC [89][90], originally thought by early investigators to be the true psychoactive analyte [64]. CYP 450 2C9, 2C19, and 3A4 are involved in the oxidation of THC [90]. More than 100 THC metabolites, including di- and trihydroxy compounds, ketones, aldehydes, and carboxylic acids, have been identified [21][70][91]. Although 11-OH-THC predominates as the first oxidation product, significant amounts of 8β-OH-THC and lower amounts of the 8α-OH-THC are formed. Much lower plasma 11-OH-THC concentrations (ca. 10% of THC concentrations) are found after cannabis smoking than after oral administration [27]. Peak 11-OH-THC concentrations occurred ca. 13 min after the start of smoking [14]. Bornheim et al. reported that 11-OH-THC and 8β-OH-THC were formed at the same rate in human-liver microsomes, with smaller amounts of ‘epoxyhexahydrocannabinol’, 8α-OH-THC, and 8-keto-THC [92]. CYP 450 2C9 is thought to be primarily responsible for the formation of 11-OH-THC, whereas CYP 450 3A catalyzes the formation of 8β-OH-THC, ‘epoxyhexahydrocannabinol’, and other minor metabolites. Less than fivefold variability in 2C9 rates of activity was observed, while much higher variability was noted for the 3A enzyme. Dihydroxylation of THC yields 8β,11-di-OH-THC. Excretion of 8β,11-di-OH-THC in urine was reported to be a good biomarker for recent cannabis use [93].

Oxidation of the psychoactive 11-OH-THC produces the inactive metabolite THC-COOH [64][94]. THC-COOH and its glucuronide conjugate are the major end products of biotransformation in most species, including man [91][95]. THC-COOH concentrations gradually increase, and are greater than THC concentrations 30−45 min after the end of smoking [96]. After ingestion of a single oral dose of Marinol® (10 mg THC), plasma THC-COOH concentrations were higher than those of THC and 11-OH-THC as early as 1 h after dosing [97]. Unlike after smoking, THC and 11-OH-THC concentrations are similar after oral THC administration.

Phase-II metabolism of THC-COOH involves addition of glucuronic acid, and, less commonly, of sulfate, glutathione, amino acids, and fatty acids via the 11-COOH group. The phenolic OH group may be a target as well. It is also possible to have two glucuronic acid moieties attached to THC-COOH, although steric hindrance at the phenolic OH group could be a factor. Addition of the glucuronide group improves water solubility, facilitating excretion, but renal clearance of these polar metabolites is low due to extensive protein binding [72]. No significant differences in metabolism between men and women have been reported [27].

After the initial distribution phase, the rate-limiting step in the metabolism of THC is its redistribution from lipid depots into blood [98]. Lemberger et al. suggested that frequent cannabis smoking could induce THC metabolism [99]. However, later studies did not corroborate this finding [8][91].

More than 30 metabolites of CBD were identified in urine, with hydroxylation of the 7-Me group and subsequent oxidation to the corresponding carboxylic acid as the main metabolic route, in analogy to THC [100].

2.3.2. Extrahepatic Metabolism

Other tissues, including brain, intestine, and lung, may contribute to the metabolism of THC, although alternate hydroxylation pathways may be more prominent [86][101-104]. An extrahepatic metabolic site should be suspected whenever total body clearance exceeds blood flow to the liver, or when severe liver dysfunction does not affect metabolic clearance [102]. Of the ten mammalian classes of CYP 450 systems, the cytochrome families 1−4 primarily metabolize xenobiotics, which are found in the liver, small intestine, peripheral blood, bone marrow, and mast cells in decreasing concentrations, with the lowest concentrations in the brain, pancreas, gall bladder, kidney, skin, salivary glands, and testes. Within the brain, higher concentrations of CYP 450 enzymes are found in the brain stem and cerebellum [102]. The hydrolyzing enzymes – non-specific esterases, β-glucuronidases, and sulphatases–are primarily found in the gastrointestinal tract. Side-chain hydroxylation of THC is prominent in THC metabolism by the lung. Metabolism of THC by fresh biopsies of human intestinal mucosa yielded polar hydroxylated metabolites that directly correlated with time and amount of intestinal tissue [101].

In a study of the metabolism of THC in the brains of mice, rats, guinea pigs, and rabbits, Watanabe et al. found that brain microsomes oxidized THC to monohydroxylated metabolites [103]. Hydroxylation of C(4) of the pentyl side chain produced the most common THC metabolite in the brains of these animals, similar to THC metabolites produced in the lung. These metabolites are pharmacologically active, but their relative activity is unknown.

2.3.3. Metabolism of Cannabidiol

CBD Metabolism is similar to that of THC, with primary oxidation of C(9) to the alcohol and carboxylic acid [8][100], as well as side-chain oxidation [88][100]. Like THC, CBD is subjected to a significant first-pass effect; however, unlike THC, a large proportion of the dose is excreted unchanged in the feces [105]. Benowitz et al. reported that CBD is an in vitro inhibitor of liver microsomal drug-metabolizing enzymes, inhibiting hexobarbital metabolism in humans [50]. Others have reported that CBD selectively inhibits THC-metabolite formation in vitro [58]. Hunt et al. reported that the pharmacokinetics of THC were not affected by CBD, except for a slight slowing of the metabolism of 11-OH-THC to THC-COOH [106]. Co-administration of CBD did not significantly affect the total clearance, volume of distribution, and terminal elimination half-lives of THC metabolites. Concentration vs. time curves, and ratios of the maximum average concentration and AUC values for 11-OH-THC/THC, THC-COOH/THC, and THC-COOH/11-OH-THC showed that CBD only partially inhibited the hydroxylation of THC to 11-OH-THC catalyzed by CYP 2C, when data were compared after oral administration of THC alone, as compared to a THC and CBD preparation [107]. THC and CBD concentrations are high in the liver after oral administration, and there is high first-pass metabolism of THC. However, the effect of CBD on hydroxylation of THC was small in comparison to overall variability.

2.4. Elimination

Within 5 d, a total of 80−90% of THC is excreted, mostly as hydroxylated and carboxylated metabolites [21][95]. More than 65% is excreted in the feces, ca. 20% being eliminated in the urine [27]. Numerous acidic metabolites are found in the urine, many of which are conjugated with glucuronic acid to increase their water solubility. The primary urinary metabolite is the acid-linked THC-COOH glucuronide conjugate [108], while 11-OH-THC predominates in the feces [21]. The concentration of free THC-COOH, and the cross-reactivity of glucuronide-bound THC-COOH enable cannabinoid immunoassays to be performed directly on non-hydrolyzed urine, but confirmation and quantification of THC-COOH is usually performed after alkaline hydrolysis or β-glucuronidase hydrolysis to free THC-COOH for measurement by GC/MS. It was initially thought that little or no THC and 11-OH-THC were excreted in the urine.

2.4.1. Terminal Elimination Half-Lives of THC-COOH

Another common problem with studying the pharmacokinetics of cannabinoids in humans is the need for highly sensitive procedures to measure low cannabinoid concentrations in the terminal phase of excretion, and the requirement for monitoring plasma concentrations over an extended period to adequately determine cannabinoid half-lives. Many studies utilized short sampling intervals of 24−72 h that underestimate terminal THC and THC-COOH half-lives. The slow release of THC from lipid-storage compartments and significant enterohepatic circulation contribute to a long terminal half-life of THC in plasma, reported to be greater than 4.1 d in chronic cannabis users [109]. Isotopically labeled THC and sensitive analytical procedures were used to obtain this drug half-life. Garrett and Hunt reported that 10−15% of the THC dose is enterohepatically circulated in dogs [98]. Johansson et al. reported a THC-COOH plasma-elimination half-life of up to 12.6 d in a chronic cannabis user, when monitoring THC-COOH concentrations over four weeks [110]. Mean plasma THC-COOH elimination half-lives were 5.2±0.8 and 6.2±6.7 d for frequent and infrequent cannabis users, respectively. Similarly, when sensitive analytical procedures and sufficient sampling periods were employed for determining the terminal urinary excretion half-life of THC-COOH, it was estimated to 3−4 d [111]. Urinary THC-COOH concentrations drop rapidly until reaching a value of ca. 20−50 ng/ml, and then decrease at a much slower rate. No significant pharmacokinetic differences between chronic and occasional users have been substantiated [112].

2.4.2. Percentage of THC Excreted as Urinary THC-COOH

An average of 93.9±24.5 mg of THC-COOH (range 34.6−171.6 μg) was measured in urine over a period of 7 d, following smoking of a single cannabis cigarette containing ca. 18 mg (1.75%) of THC [113]. The average amount of THC-COOH excreted in the same time period following the high dose (3.55% THC cigarette, ca. 34 mg THC) was 197.4±33.6 μg (range 107.5−305.0 μg). This represents an average of only 0.54±0.14 and 0.53±0.09% of the original amount of THC in the low- and high-dose cigarettes, respectively. These small percentages of the total THC dose found in the urine as THC-COOH are not surprising, considering the many factors that influence THC-COOH excretion after smoking. Prior to harvesting, cannabis plant material contains little active THC. When smoked, THC carboxylic acids spontaneously decarboxylate to produce THC, with nearly complete conversion upon heating. Pyrolysis of THC during smoking destroys additional drug. Drug availability is further reduced by loss of drug in the side-stream smoke and drug remaining in the unsmoked cigarette butt. These factors contribute to high variability in drug delivery by the smoked route. It is estimated that the systemic availability of smoked THC is ca. 8−24%, and that bioavailability depends strongly upon the experience of the cannabis users [5][17][114]. THC Bioavailability is reduced due to the combined effect of these factors; the actual available dose is much lower than the amount of THC and THC precursor present in the cigarette. Most of the THC dose is excreted in the feces (30−65%), rather than in the urine (20%) [27][115]. Another factor affecting the low amount of recovered dose is measurement of a single metabolite. However, numerous cannabinoid metabolites are produced in humans as a result of THC metabolism, most of which are not detected or included in the calculations based on GC/MS analysis.

Following controlled oral administration of THC in dronabinol or hemp oil, urinary cannabinoid excretion was characterized in 4,381 urine specimens [116][117]. THC Doses of 0.39−14.8 mg/d (from hemp oils or Marinol®) were administered for 5 d. All urine voids, collected over ten weeks, were tested by immunoassay and GC/MS analysis. With the U.S. federally mandated 50 μg/l immunoassay cutoff, and during ingestion of the two low doses typical of current hemp-oil THC concentrations (<0.5 mg/d), mean detection rates were below 0.2% [116]. The two high doses (7.5 and 14.8 mg/d) produced mean detection rates of 23−46%, with intermittent positive tests up to 118 h. Maximum THC-COOH concentrations were 5.4−38.2 ng/ml for the low, and 19.0−436 μg/l for the high doses. The availability of cannabinoid-containing foodstuffs, cannabinoid-based therapeutics, and continued abuse of oral cannabis require scientific data for the accurate interpretation of cannabinoid tests. These data demonstrate that it is possible, but unlikely, for a urine specimen to test positive at the federally mandated cannabinoid cutoffs, following manufacturer’s dosing recommendations for the ingestion of hemp oils of low THC concentration. Urine tests have a high likelihood of being positive following Marinol® therapy.

These investigators also reported no significant differences (P≤0.05) in mean time of maximum excretion rate, mean maximum excretion rate, and mean terminal elimination half-life between the four THC doses (0.39−14.8 mg/d), with ranges of 67.4−94.9 h, 0.9−16.3 μg/h, and 44.2−64.0 h, respectively [117]. Mean apparent elimination half-lives (t1/2) of 24.1±7.8 and 21.1±4.3 h for the low (7.5 mg/d) and high (14.8 mg/d) doses, respectively, were calculated from the excretion-rate curve prior to the last urine sample, with a THC-COOH concentration ≥15 ng/ml. An average of only 2.9±1.6%, 2.5±2.7%, 1.5±1.4%, and 0.6±0.5% of the THC in the dose of 0.39, 0.47, 7.5, and 14.8 mg/d, respectively, was excreted in the form of THC-COOH in the urine over each dosing session (14 d). This study demonstrated that the terminal urinary elimination half-life of THC-COOH following oral administration is ca. 2−3 d for doses ranging from 0.39−14.8 mg/d. These data also demonstrate that the apparent THC-COOH urinary elimination half-life, prior to reaching a concentration of 15 ng/ml, is significantly shorter than the terminal urinary elimination half-life.

2.4.3. Cannabinoid–Glucuronide Conjugates

Specimen preparation for cannabinoid testing frequently includes a hydrolysis step to free cannabinoids from their glucuronide conjugates. Most GC/MS procedures of urine samples measure total THC-COOH, following either an enzymatic hydrolysis with β-glucuronidase or, more commonly, an alkaline hydrolysis with NaOH. Alkaline hydrolysis appears to efficiently hydrolyze the ester glucuronide linkage.

2.4.4. Urinary Biomarkers of Recent Cannabis Use

Significantly higher concentrations of THC and 11-OH-THC in urine are observed, when Escherichia coli β-glucuronidase is used in the hydrolysis method, compared to either β-glucuronidase from Helix pomatia or base treatment [118][119]. THC and 11-OH-THC primarily are excreted in urine as glucuronide conjugates that are resistant to cleavage by alkaline hydrolysis or by enzymatic hydrolysis employing some types of β-glucuronidase. Kemp et al. demonstrated that β-glucuronidase from E. coli was needed to hydrolyze the ether glucuronide linkages of the active cannabinoid analytes. Mean THC concentrations in urine specimens from seven subjects, collected after each had smoked a single marijuana cigarette (3.58% of THC), was 22 ng/ml, when the E. coli β-glucuronidase hydrolysis method was used; in contrast, the observed THC concentrations were nearly zero when using either H. pomatia β-glucuronidase or base hydrolysis [118][119]. Similar differences were found for 11-OH-THC, with a mean concentration of 72 ng/ml for the E. coli method, but concentrations <10 ng/ml for the other methods. The authors suggested that finding THC and/or 11-OH-THC in the urine might provide a reliable marker of recent cannabis use, but adequate data from controlled drug-administration studies were not yet available to support or refute this observation. Using a modified analytical method with E. coli β-glucuronidase, we have analyzed hundreds of urine specimens collected after controlled THC administration. We found that 11-OH-THC may be excreted in the urine of chronic cannabis users for a much longer period of time, beyond the period of pharmacodynamic effects and performance impairment. Additional research is necessary to determine the validity of estimating time of cannabis use from THC and 11-OH-THC concentrations in urine.

3. Interpretation of Cannabinoid Concentrations in Biological Fluids

3.1. Plasma Concentrations

Compared to other drugs of abuse, analysis of cannabinoids presents some difficult challenges. THC and 11-OH-THC are highly lipophilic, and present in low concentrations in body fluids. Complex specimen matrices, i.e., blood, sweat, or hair, may require multi-step extractions to separate cannabinoids from endogenous lipids and proteins. Care must be taken to avoid low recoveries of cannabinoids due to their high affinity to glass and plastic containers, and to alternate matrix-collection devices [120-123]. THC and THC-COOH are predominantly found in the plasma fraction of blood, where 95−99% are bound to lipoproteins. Only ca. 10% of either compound is found in the erythrocytes [124]. Whole-blood cannabinoid concentrations are approximately one-half the concentrations found in plasma specimens, due to the low partition coefficient of drug into erythrocytes [96][125][126].

3.1.1. Intravenous THC Administration

Kelly et al. intravenously administered 5 mg of THC to eight males, and then periodically monitored THC, THC-COOH, and THC-COOH–glucuronide conjugates by GC/MS (1 ng/ml detection limit for THC and THC-COOH) in plasma with and without alkaline hydrolysis for up to 10 h, and then once daily for up to 12 d [77]. The elimination half-lives of THC, THC-COOH, and THC-COOH–glucuronide conjugate in the plasma of frequent cannabis users were 116.8 min, 5.2 d, and 6.8 d, respectively, and 93.3 min, 6.2 d, and 3.7 d in infrequent users. Conjugated THC-COOH was detected in the plasma of 75% of the frequent and 25% of the infrequent users after 12 d.

3.1.2. Smoked Cannabis

THC Detection times in plasma of 3.5−5.5 h were reported in individuals who smoked two cannabis cigarettes containing a total of ca. 10 mg of THC (GC/MS detection limit 0.8 ng/ml) [93], and up to 13 d for deuterated THC in the blood of chronic cannabis users, who smoked four cigarettes containing deuterium-labeled THC (GC/MS detection limit 0.02 ng/ml) [109]. In the latter study, the terminal half-life of THC in plasma was determined to be ca. 4.1 d, as compared to frequent estimates of 24−36 h in several other studies [27][59][127] that lacked the sensitivity and the lengthy monitoring window of the radiolabeled protocol.

Few controlled drug-administration studies have monitored active 11-OH-THC plasma concentrations. Huestis et al. found plasma 11-OH-THC concentrations to be ca. 6−10% of the concurrent THC concentrations for up to 45 min after the start of smoking [14]. Mean peak 11-OH-THC concentrations occurred 13.5 min (range 9.0−22.8 min) after the start of smoking, and were 6.7 ng/ml (range 3.3−10.4 ng/ml) and 7.5 ng/ml (range 3.8−16 ng/ml) after smoking one cannabis cigarette containing 1.75 or 3.55% of THC, respectively. The concentrations of 11-OH-THC decreased gradually, with mean detection times of 4.5 and 11.2 h after the two doses.

The concentrations of THC-COOH were monitored in human plasma for 7 d after controlled cannabis smoking [14]. This inactive metabolite was detected in the plasma of all subjects by 8 min after the start of smoking. THC-COOH concentrations in plasma increased slowly, and reached a plateau for up to 4 h. Peak concentrations were consistently lower than peak THC concentrations, but were higher than 11-OH-THC peak concentrations. Mean peak THC-COOH concentrations were 24.5 ng/ml (range 15−54 ng/ml) and 54.0 ng/ml (range 22−101 ng/ml) after smoking the low- (1.75% of THC) or high-dose (3.55% of THC) cigarette, respectively. Following smoking of the lower dose, THC-COOH was detected from 48−168 h, with a mean of 84 h. Detection times ranged from 72−168 h, with a mean of 152 h, following smoking of the higher dose. The time course of detection of THC-COOH is much longer than either that of THC or 11-OH-THC. The AUC for the mean data from 0−168 h was 36.5 and 72.2 ng × h/ml, respectively, for the low- and high-dose conditions, demonstrating a dose-response relationship for the mean data [14]. Fig. 2 (see above) shows individual THC-concentration time profiles for six subjects, demonstrating the large inter-subject variability of the smoked route of drug administration. Moeller et al. measured serum THC and THC-COOH concentrations in 24 experienced users from 40−220 min after smoking cannabis cigarettes with a THC content of 300 μg/kg [128]. Mean serum THC and THC-COOH concentrations were ca. 13 and 22 ng/ml at 40 min, and 1 and 13 ng/ml at 220 min after smoking, respectively. The half-life of the rapid-distribution phase of THC was estimated to be 55 min over this short sampling interval.

Most plasma or whole-blood analytical methods for the determination of cannabinoids have not included measurement of the glucuronide conjugates of THC, 11-OH-THC, or THC-COOH. The relative percentages of free and conjugated cannabinoids in plasma after different routes of drug administration are unclear. Even the efficacy of alkaline- and enzymatic-hydrolysis procedures to release analytes from their conjugates is not fully understood [24][77][93][115][118][119][129-133]. In general, the concentrations of conjugate are believed to be lower in plasma, following intravenous or smoked administration, but may be of much greater magnitude after oral intake. There is no indication that the glucuronide conjugates are active, although supporting data are lacking.

3.1.3. Oral Administration

After oral and sublingual administration of THC, THC-containing food products, or cannabis-based extracts, the concentrations of THC and 11-OH-THC are much lower than those found upon smoked administration. Plasma concentrations of THC in patients receiving 10−15 mg of Marinol® as an anti-emetic were low or even non-measurable in 57 patients [134]. After daily administration of 10−15 mg of Marinol®, Brenneisen et al. found peak plasma concentrations of THC and THC-COOH of 2.1−16.9 ng/ml within 1−8 h, and of 74.5−244 ng/ml within 2−8 h, respectively [42]. In our oral, controlled THC-administration studies, peak plasma THC, 11-OH-THC, and THC-COOH concentrations were less than 6.5, 5.6, and 24.4 ng/ml, respectively, following up to 14.8 mg/d of THC in the form of THC-containing food products or Marinol® [135]. Peak concentrations and time-to-peak concentrations varied sometimes considerably between subjects. Plasma THC and 11-OH-THC were negative for all participants and for all doses by 16 h after administration of the last THC dose. Plasma THC-COOH persisted for a longer period of time, following the two highest doses of 7.5 mg/d of dronabinol, and 14.8 mg/d of THC in hemp oil. Ohlsson et al. reported that orally administered THC (20 mg) in a cookie yielded low and irregular plasma concentrations, compared to intravenous and inhaled THC [5].

3.1.4. Cannabinoid Concentrations after Frequent Use

Most THC plasma data have been collected following acute exposure; less is known of plasma THC concentrations in frequent users. Peat reported THC, 11-OH-THC, and THC-COOH plasma concentrations in frequent cannabis users of 0.86±0.22, 0.46±0.17, and 45.8±13.1 ng/ml, respectively, a minimum of 12 h after the last smoked dose [136]. No difference in terminal half-life in frequent or infrequent users was observed. Johansson et al. administered radiolabeled THC to frequent cannabis users, and found a terminal elimination half-life of 4.1 d for THC in plasma, due to extensive storage and release from body fat [109].

3.1.5. Prediction Models for Estimation of Cannabis Exposure

There continues to be controversy in the interpretation of cannabinoid results from blood analysis, some general concepts having wide support. A dose-response relationship has been demonstrated for smoked THC and THC plasma concentrations [16][17]. It is well-established that plasma THC concentrations begin to decline prior to the time of peak effects, although it has been shown that THC effects appear rapidly after initiation of smoking [15]. Individual drug concentrations and ratios of cannabinoid metabolite to parent drug concentration have been suggested as potentially useful indicators of recent drug use [24][137]. Some 45 min after cannabis smoking, the ratio [THC-COOH]/[THC] in the plasma was reported to be >1 [77]. This is in agreement with results reported by Mason and McBay [96], and those by Huestis et al. [15], who found that peak effects occurred when THC and THC-COOH concentrations reached equivalency, within 30−45 min after initiation of smoking. Measurement of cannabinoid analytes with short time courses of detection (e.g., 8β,11-dihydroxytetrahydrocannabinol) as markers of recent THC exposure has not found widespread use [96]. Recent exposure (6−8 h) and possible impairment have been linked to plasma THC concentrations in excess of 2−3 ng/ml [14][96]. Gjerde et al. [138] suggested that 1.6 ng/ml of THC in whole blood may indicate possible impairment. This correlates well with the suggested concentration of plasma THC, due to the fact that THC in hemolyzed blood is approximately one-half the concentration of plasma THC [139]. Interpretation is further complicated by residual THC and THC-COOH concentrations found in blood of frequent cannabis users. In general, it is suggested that chronic cannabis smokers may have residual plasma THC concentrations of <2 ng/ml some 12 h after smoking cannabis [136]. Significantly higher residual concentrations of THC-COOH may be found.

Accurate prediction of the time of cannabis exposure would provide valuable information in establishing the role of cannabis as a contributing factor to events under investigation. Two mathematical models for the prediction of time of cannabis use from the analysis of a single plasma specimen for cannabinoids were developed [140]. Model I is based on THC concentrations, and model II is based on the ratio [THC-COOH]/[THC] in the plasma ( Fig. 4 ). Both models correctly predicted the times of exposure within the 95%-confidence interval for more than 90% of the specimens evaluated. Furthermore, plasma THC and THC-COOH concentrations reported in the literature, following oral and smoked cannabis exposure, in frequent and infrequent cannabis smokers, and with measurements obtained by a wide variety of methods (including radioimmunoassay and GC/MS analysis), were evaluated with these models. Plasma THC concentrations <2.0 ng/ml were excluded from use in both models, due to the possibility of residual THC concentrations in frequent smokers. Manno et al. evaluated the usefulness of these models in predicting the time of cannabis use in a controlled cannabis-smoking study [132]. The models were found to accurately predict the time of last use within the 95%-confidence intervals. Due to the limited distribution of THC and THC-COOH into red blood cells, it is important to remember, when comparing whole-blood THC and/or THC-COOH concentrations to plasma concentrations, to double the whole-blood concentration prior to comparison.

Predictive mathematical models for estimating the elapsed time of last cannabis use based on plasma THC and THC-COOH concentrations. Reprinted and adapted with permission by Journal of Analytical Toxicology, p. 285 in [140], Fig. 1 .

More recently, the validation of these predictive models was extended to include estimation of time of use after multiple doses of THC and at low THC concentrations (0.5−2 ng/ml), situations that were not included in the original models [141]. Some 38 cannabis users each smoked a cigarette containing 2.64% of THC in the morning, and 30 also smoked a second cigarette in the afternoon. Blood specimens (n=717) were collected at intervals after smoking, and plasma THC and THC-COOH concentrations were measured by GC/MS analysis. The predicted times of cannabis smoking, based on each model, were then compared to the actual smoking times. The most accurate approach applied a combination of models I and II. For all 717 plasma specimens, 99% of the predicted times of last use were within the 95%-confidence interval, 0.9% were overestimated, and none was underestimated. For 289 plasma specimens collected after multiple doses, 97% were correct, with no underestimates. All time estimates were correct for 77 plasma specimens, with THC concentrations of 0.5−2.0 ng/ml, a concentration range not previously examined. The models provide an objective, validated method for assessing the contribution of cannabis to accidents or clinical symptoms.

These models also appeared to be valuable when applied to the small amount of data from published studies of oral ingestion available at the time. Additional studies were performed to determine if the predictive models could estimate last usage after multiple oral doses, a route of administration more popular with the advent of cannabis therapies. A total of 18 subjects received oral THC, as Marinol® or hemp oil [142]. Each of twelve subjects in one group received a single oral dose of dronabinol (10 mg of synthetic THC). In another protocol, six subjects received four different oral daily doses, divided into thirds, and administered with meals for five consecutive days. There was a 10-d washout period between each dosing regimen. The daily doses were 0.39, 0.47, and 14.8 mg of THC in hemp oil, and 7.5 mg in the form of dronabinol. Blood specimens were collected throughout the study, and analyzed for plasma THC and THC-COOH levels by GC/MS analysis, with quantification limits of 0.5 and 1.0 ng/ml, respectively. The actual times between ingestion of THC and blood collection spanned 0.5−16 h. All plasma specimens with analyte concentrations that were equal to or larger than the quantification limit (n=90) were evaluated. Models I and II correctly predicted the time of last THC ingestion in the case of 74.4 and 90.0% of the plasma specimens, respectively. Some 96.7% of the predicted times were correct, with one overestimate and two underestimates, using the time interval defined by the lowest and highest 95%-confidence limit of both models. These results provide further evidence of the usefulness of the predictive models in estimating the time of last oral THC ingestion following single or multiple doses.

3.2. Urine Concentrations

Detection of cannabinoids in urine is indicative of prior cannabis exposure, but the long excretion half-life of THC-COOH in the body, especially in chronic cannabis users, makes it difficult to predict the timing of past drug use. In a single extreme case, one individual’s urine was positive at a concentration >20 ng/ml (by immunoassay) up to 67 d after last drug exposure [143]. This individual had used cannabis heavily for more than ten years. However, a naive user’s urine may be found negative by immunoassay after only a few hours following smoking of a single cannabis cigarette [144]. Assay cutoff concentrations and the sensitivity and specificity of the immunoassay affect drug-detection times. A positive urine test for cannabinoids indicates only that drug exposure has occurred. The result does not provide information on the route of administration, the amount of drug exposure, when drug exposure occurred, or the degree of impairment.

To date, there are too few urinary data on THC and 11-OH-THC levels to guide interpretation of positive urine cannabinoid tests; however, data are available for guiding interpretation of total urinary THC-COOH concentrations. Total THC-COOH concentrations include both the free THC-COOH and THC-COOH–glucuronide conjugate concentrations determined after alkaline or enzymatic hydrolysis. Substantial intra- and inter-subject variability occurs in patterns of THC-COOH excretion. THC-COOH concentration in the first specimen after smoking is indicative of how rapidly the metabolite can appear in urine. Mean first urine THC-COOH concentrations were 47±22.3 and 75.3±48.9 ng/ml after smoking one cigarette containing 1.75 or 3.55% of THC, respectively [113]. Some 50% of the subjects’ first urine specimen after the low dose, and some 83% of the first urine specimens after the high dose were positive by GC/MS at a THC-COOH cutoff concentration of 15 ng/ml. Thus, THC-COOH concentrations in the first urine specimen are dependent upon the relative potency of the cigarette, the elapsed time following drug administration, smoking efficiency, and individual differences in drug metabolism and excretion. Mean peak urine THC-COOH concentrations averaged at 89.8±31.9 ng/ml (range 20.6−234.2 ng/ml) and 153.4±49.2 ng/ml (range 29.9−355.2 ng/ml) following smoking of ca. 15.8 and 33.8 mg of THC, respectively. The mean times of peak urine concentration were 7.7±0.8 h and 13.9±3.5 h for the low and high dose, respectively. Although peak concentrations appeared to be dose-related, there was a twelvefold variation between individuals.

3.2.1. THC-COOH Detection Windows in Urine

Drug detection time, or the duration of time after drug administration in which the urine of an individual tests positive for cannabinoids, is an important factor in the interpretation of urine drug results. Detection time is dependent on pharmacological factors (e.g., drug dose, type of administration, rates of metabolism and excretion) and analytical factors (e.g., assay sensitivity, specificity, accuracy). Mean detection times in urine following smoking vary considerably between subjects, even in controlled smoking studies, where cannabis dosing is standardized and smoking is computer-paced. During the terminal elimination phase, consecutive urine specimens may fluctuate between positive and negative, as THC-COOH concentrations approach the cutoff concentration. It may be important in drug-treatment settings or in clinical trials to differentiate between new drug use and residual excretion of previously used cannabinoids. After smoking a cigarette containing 1.75% of THC, three out of six subjects had additional positive urine samples interspersed between negative urine samples [144]. This had the effect of producing much longer detection times for the last positive specimen. With a currently accepted confirmation cutoff of 15 ng/ml for THC-COOH, which is most often used in urine-drug testing, the mean GC/MS THC-COOH detection times for the last positive urine sample, following the smoking of a single cigarette with 1.75 or 3.55% of THC, were 33.7±9.2 h (range 8−68.5 h) and 88.6±23.2 h (range 57−122.3 h), respectively. Wingert et al. reported that lowering the urine immunoassay cutoff from 50 to 20 ng/ml, and employing a confirmation cutoff of 10 ng/ml, increased the THC positive rate from 2.8 to 4.1% [145].

3.2.2. Normalization of Cannabinoid Urine Concentrations to Urine Creatinine Concentrations

Normalization of cannabinoid concentration to urine creatinine concentration aids in the differentiation of new from prior cannabis use, and reduces the variability of drug measurement due to urine dilution. Due to the long half-life of drug in the body, especially in chronic cannabis users, toxicologists and practitioners are frequently asked to determine if a positive urine test represents a new episode of drug use or represents continued excretion of residual drug. Random urine specimens contain varying amounts of creatinine, depending on the degree of concentration of the urine. Hawks first suggested creatinine normalization of urine test results to account for variations in urine volume in the bladder [146]. Whereas urine volume is highly variable due to changes in liquid, salt, and protein intake, exercise, and age, creatinine excretion is much more stable.

Manno et al. recommended that an increase of 150% in the creatinine-normalized cannabinoid concentration above the previous specimen can be considered indicative of a new episode of drug exposure [147]. If the increase is greater than or equal to the threshold selected, then new use is predicted. This approach has received wide attention for potential use in treatment and employee-assistance programs, but there was limited evaluation of the usefulness of this ratio under controlled dosing conditions.

Huestis and Cone conducted a controlled clinical study of the excretion profile of creatinine and cannabinoid metabolites in a group of six cannabis users, who smoked two different doses of cannabis, separated by weekly intervals [148]. As seen in Fig. 5 , normalization of urinary THC-COOH concentration to the urinary creatinine concentration produces a smoother excretion pattern and facilitates interpretation of consecutive urine drug-test results.

Urine concentrations of THC-COOH and THC-COOH/creatinine for one subject following smoking of a single cannabis cigarette containing 3.55% of THC. Reprinted and adapted with permission by Journal of Analytical Toxicology, p. 450 in [148], Fig. 3 .

Being able to differentiate new cannabis use from residual THC-COOH excretion in urine would be highly useful for drug treatment, criminal justice, and employee assistance drug testing programs. We evaluated the ratios of creatinine normalized THC-COOH concentrations from more than 1800 pairs of urine specimens collected during a controlled smoked THC administration study. The ratio times 100 of the creatinine normalized later specimen divided by the creatinine normalized earlier specimen were evaluated for determining the best ratio to predict new cannabis use. A relative operating characteristic (ROC) curve was constructed from sensitivity and specificity data for 26 different cutoffs, ranging from 10 to 200%. The most accurate ratio (85.4%) was 50%, with a sensitivity of 80.1%, a specificity of 90.2%, and false positive and false negative predictions of 5.6 and 7.4%, respectively. When the previously recommended increase of 150% was used as a threshold for new use, sensitivity of detecting new use was only 33.4%, and specificity was high (99.8%), for an overall accuracy prediction of 74.2%. To further substantiate the validity of the derived ROC curve, urine-cannabinoid-metabolite and creatinine data from another controlled clinical trial that specifically addressed water dilution as a means of specimen adulteration were evaluated [149]. Sensitivity, specificity, accuracy, and false positives and negatives were 71.9, 91.6, 83.9, 5.4, and 10.7%, respectively, when the 50% criteria was applied. These data indicate that selection of a threshold to evaluate sequential creatinine-normalized urine drug concentrations can improve the ability to distinguish residual excretion from new drug usage.

Lafolie et al. reported the results of urinary excretion of cannabinoids by a heavy cannabis smoker [150]. Cannabinoids were detectable for 93 d after cessation of smoking, with a decreasing ratio of cannabinoids to creatinine over time. An excretion half-life of 32 d was determined. When cannabinoid concentrations had not been normalized to creatinine concentrations, a number of false positive indications of new drug use would have occurred.

Fraser et al. conducted a series of studies evaluating the application of [THC-COOH]/[creatinine] ratios for urine specimens collected at least 96 h apart from heavy, chronic cannabis users in an outpatient setting [151-153]. Mean urinary THC-COOH concentrations, mean [THC-COOH]/[creatinine] ratios, and mean [THC-COOH]/[creatinine] ratios from consecutively collected specimens were considerably above the proposed 50% ratio to differentiate new use. The proposed 50% ratio was developed from more than 1,800 urine specimens collected after occasional cannabis use on a secure research unit [148]. As suggested, the 50% ratio may not be appropriate for differentiating new drug use from residual drug excretion in heavy users. [THC-COOH]/[Creatinine] ratios decrease reliably until THC-COOH concentrations are between 20−50 ng/ml. Within this range, cannabinoid excretion is more variable, most likely based on the slow and variable release of stored THC from fat tissue. The factors governing release of THC stores are not known. Additional research is being performed to attempt to determine appropriate ratio cutoffs for reliably predicting new drug use in heavy, chronic users.

3.3. Oral-Fluid Testing

Oral fluid also is a suitable specimen for monitoring cannabinoid exposure, and is being evaluated for driving under the influence of drugs, drug treatment, workplace drug testing, and for clinical trials [154-159]. Adequate sensitivity is best achieved with an assay directed toward detection of THC, rather than of 11-OH-THC or THC-COOH. The oral mucosa is exposed to high concentrations of THC during smoking, and serves as the source of THC found in oral fluid. Only minor amounts of drug and metabolites diffuse from the plasma into oral fluid [146]. Following intravenous administration of radiolabeled THC, no radioactivity could be demonstrated in oral fluid [160]. No measurable 11-OH-THC or THC-COOH were found by GC/MS (detection limit 0.5 ng/ml) in oral fluid for 7 d, following cannabis smoking [161], or in oral fluid from 22 subjects positive for THC-COOH in the urine [162]. Oral fluid collected with the Salivette collection device was positive for THC in 14 of these 22 participants. Although no 11-OH-THC or THC-COOH was identified by GC/MS, CBN and CBD were found in addition to THC. Several hours after smoking, the oral mucosa serves as a depot for release of THC into the oral fluid. In addition, as detection limits continue to decrease with the development of new analytical instrumentation, it may be possible to measure low concentrations of THC-COOH in oral fluid.

Detection times of cannabinoids in oral fluid are shorter than in urine, and more indicative of recent cannabis use [154][156]. Oral-fluid THC concentrations temporally correlate with plasma cannabinoid concentrations and behavioral and physiological effects, but wide intra- and inter-individual variation precludes the use of oral-fluid concentrations as indicators of drug impairment [161][163]. THC may be detected at low concentrations by radioimmunoassay for up to 24 h after use.

Fig. 6 depicts excretion of THC in oral fluid and plasma, as well as creatinine-normalized THC-COOH excretion in urine in one subject after smoking a single cannabis cigarette containing 3.55% of THC [164]. After smoking cannabis, oral-fluid cannabinoid tests were positive for THC by GC/MS/MS, with a cutoff of 0.5 ng/ml for 13±3 h (range 1−24 h) [165]. After these times, occasional positive oral-fluid results were interspersed with negative tests for up to 34 h.

Peel et al. tested oral-fluid samples from 56 drivers, suspected of being under the influence of cannabis, with the EMIT® screening test and by GC/MS analysis [166]. They suggested that the ease and non-invasiveness of sample collection made oral fluid a useful alternative matrix for detection of recent cannabis use. Oral-fluid samples also are being evaluated in the European Union’s Roadside Testing Assessment (ROSITA) project to reduce the number of individuals driving under the influence of drugs and to improve road safety. The ease and non-invasiveness of oral-fluid collection, reduced hazards in specimen handling and testing, and shorter detection window are attractive attributes to the use of this specimen for identifying the presence of potentially performance-impairing drugs.

Laloup et al. compared THC levels in oral fluid (collected with the Intercept® device) and plasma from 139 individuals suspected of driving under the influence of drugs, using LC/MS/MS [167]. They determined that, with a limit of quantification of 0.5 ng/ml in the plasma, the optimal cut-off in oral fluid was 1.2 ng/ml, yielding a sensitivity of 94.7% and a specificity of 92.0%. When a higher plasma cutoff was the target (2 ng/ml), oral fluid THC concentrations of 5.2 ng/ml reliably predicted a positive blood THC result, with a sensitivity of 91.6% and a specificity of 88.6%.

In a recent study of smoked and oral cannabis, the Intercept DOA Oral-Specimen-Collection Device and GC/MS/MS (cutoff 0.5 ng/ml) were paired to monitor oral-fluid cannabinoids in ten participants [165]. As mentioned above, oral-fluid specimens tested positive for up to 34 h. A different oral-fluid collection device, the Cozart RapiScan device, was used with a cannabinoid cutoff of 10 ng/ml to screen for cannabis use [168]. Positive oral-fluid cannabinoid tests were not obtained more than 2 h after last use, suggesting that much lower cutoff concentrations were needed to improve sensitivity. A procedure for direct analysis of cannabinoids in oral fluid with solid-phase micro-extraction and ion-trap GC/MS has been developed, with a limit of detection of 1.0 ng/ml [169]. Detection of cannabinoids in oral fluid is a rapidly developing field; however, there are many scientific issues to resolve. One of the most important is the degree of absorption of the drug to oral-fluid collection devices.

Recently, there has been renewed interest in oral-fluid drug testing for programs associated with drug treatment, workplace, and driving under the influence of drugs. Small and inconsistent specimen volume collection, poor extraction of cannabinoids from the collection device, low analyte concentrations for cannabinoids, and the potential for external contamination from environmental smoke are limitations to this monitoring method. Recently, independent evaluations of the extraction of cannabinoids from the collection device [170-173] and measurement of oral-fluid THC-COOH in concentrations as low as picograms per milliliter appear to adequately address these potential problems. Day et al. reached a detection limit of 10 pg/ml for THC-COOH in oral fluid by GC/MS/MS [174]. Moore et al. developed a GC/MS method using a micro-fluidic Dean‘s switch for two-dimensional (2D) chromatography to sufficiently improve signal to noise, allowing the monitoring of THC-COOH concentrations of ≥ 2 pg/ml in oral fluid [175]. Extraction efficiency for THC-COOH from the Quantisal™ (Immunalysis, Pomona, CA) oral-fluid collection device was 80% at a concentration of 10 pg/ml, with a coefficient of variation of 8.23%. The extraction efficiency of the buffer was reported to be between 79.6 and 91.4% for various concentrations of THC [173]. Specimens collected almost immediately after smoking cannabis, i.e., after 15 and 45 min, and later, after 1, 2, and 8 h, all contained THC-COOH. This new method was used for the analysis of 143 oral-fluid specimens, screening positive for cannabinoids by Enzyme-Linked Immunosorbent Assay (ELISA). Some 95 specimens (66.4%) tested positive for THC and THC-COOH; 14 (9.7%) were positive for THC-COOH only, and 27 (18.8%) were positive for THC only [176]. The observation that THC-COOH was found in 76.2% of the tested oral-fluid specimens, screening positive for cannabinoids, suggests that there is a definitive means of differentiating passive cannabis exposure from actual cannabis usage. This limitation has curtailed the use of oral-fluid testing to monitor cannabis use.

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Niedbala et al. evaluated passive contamination of oral fluid in individuals exposed to cannabis smoke in an enclosed car [177]. First, oral-fluid collection devices were contaminated when opened within the smoke-filled car. When the specimens were collected outside of the car, immediately following smoking, specimens from passive smokers were negative. Environmental cannabis smoke can contaminate collection devices, unless specimens are collected outside the area of smoke contamination.

3.4. Cannabinoids in Sweat

To date, there are no published data on the excretion of cannabinoids in sweat following controlled THC administration, although our laboratory at NIH is conducting such research. Sweat testing is being applied to monitor cannabis use in drug treatment, criminal justice, workplace drug testing, and clinical studies [161][178]. In 1989, Balabanova and Schneider used radioimmunoassay to detect cannabinoids in apocrine sweat [179]. Currently, there is a single commercially available sweat-collection device, the PharmChek patch (PharmChem Laboratories, Texas, USA). Generally, the patch is worn for 7 d, and then exchanged for a new patch once each week during visits to the treatment clinic or parole officer. Theoretically, this permits constant monitoring of drug use throughout the week, extending the window of drug detection and improving test sensitivity. As with oral-fluid testing, this is a developing analytical technique, with much to be learned about the pharmacokinetics of cannabinoid excretion in sweat, potential re-absorption of THC by the skin, possible degradation of THC on the patch, and adsorption of THC onto the patch-collection device. It is known that THC is the primary analyte detected in sweat, with little 11-OH-THC and THC-COOH. Understanding the pharmacokinetics of THC excretion also is important for the interpretation of hair cannabinoid tests, as sweat has been shown to contribute to the amount of drug found in hair (see below).

Several investigators have evaluated the sensitivity and specificity of different screening assays for detecting cannabinoids in sweat [157][180]. Kintz et al. identified THC (4−38 ng/patch) in 20 known heroin abusers who wore the PharmChek patch for 5 d, while attending a detoxification center [181]. Sweat was extracted with MeOH, and analyzed by GC/MS. The same investigators also evaluated forehead swipes with cosmetic pads for monitoring cannabinoids in sweat from individuals suspected of driving under the influence of drugs [162]. THC, but not 11-OH-THC or THC-COOH, was detected (4−152 ng/pad) by GC/EI-MS in the sweat of 16 out of 22 individuals who tested positive for cannabinoids in urine. Ion-trap tandem mass spectrometry also has been used to measure cannabinoids in sweat collected with the PharmChek sweat patch, with a detection limit of 1 ng/patch [182].

3.5. Cannabinoids in Hair

There are multiple mechanisms for the incorporation of cannabinoids in hair. THC and its metabolites may be incorporated into the hair bulb that is surrounded by capillaries. Drug may also diffuse into hair from sebum secreted onto the hair shaft, and from sweat excreted onto the skin surface. Drug may also be incorporated into hair from the environment. Cannabis is primarily smoked, providing an opportunity for environmental contamination of hair with THC in cannabis smoke. Basic drugs such as cocaine and methamphetamine concentrate in hair due to ionic bonding to melanin, the pigment in hair that determines hair color. The more neutral and lipophilic THC is not strongly bound to melanin, resulting in much lower concentrations of THC in hair as compared to other drugs of abuse. Usually, THC is present in hair at a higher concentration than its THC-COOH metabolite [183-186].

An advantage of measuring THC-COOH in hair is that this compound is not present in cannabis smoke, avoiding the issue of passive exposure from the environment. Analysis of cannabinoids in hair is challenging due to the high analytical sensitivity required. THC-COOH is present in the femto- to picogram range per milligram of hair. GC/MS/MS Analysis has been required in most analytical investigations, but a new procedure based on GC/MS equipped with a Dean‘s switch and cryofocusing was recently published [187]. Cirimele et al. [188] proposed a novel approach to the screening of hair specimens for the presence of cannabinoids in hair. They developed a rapid, simple GC/MS screening method for THC, CBN, and CBD in hair, which did not require derivatization prior to analysis. The method was found to be a sensitive screen for cannabis detection by GC/MS analysis; identification of THC-COOH was recommended as a confirmatory procedure.

It is difficult to conduct controlled cannabinoid-administration studies on the disposition of cannabinoids in hair because of the inability to differentiate administered drug from previously self-administered cannabis. If isotopically labeled drug were administered, it would be possible to identify newly administered drug in hair. There are advantages to monitoring drug use with hair testing, including a wide window of drug detection, a less invasive specimen-collection procedure, and the ability to collect a second specimen at a later time. However, one of the weakest aspects of testing for cannabinoids in hair is the low sensitivity of drug detection in this alternate matrix.

In the only controlled cannabinoid dosing study published to date, Huestis et al. collected 53 head-hair specimens from 38 males with a history of cannabis use documented by questionnaire, urinalysis, and controlled, double-blind administration of THC [189]. Subjects completed a questionnaire indicating daily cannabis use (N=18) or non-daily use, i.e., smoking one to five cannabis cigarettes per week (N=20). Hair specimens were collected from each subject at the time of admittance to a closed research unit, following smoking of two cigarettes containing 2.7% of THC (N=13), or following multiple oral doses with a total of 116 mg THC (N=2). Pre- and post-dose detection rates did not differ statistically. Therefore, all 53 specimens were considered as one group. Some 19 specimens (36%) had no detectable THC or THC-COOH at the GC/MS/MS limits of quantification of 1.0 and 0.1 pg/mg hair, respectively. Two specimens (3.8%) had measurable THC only, 14 (26%) showed THC-COOH only, and 18 (34%) had both cannabinoids. Detection rates were significantly different (p<0.05, Fisher‘s exact test) between daily cannabis users (85%) and non-daily users (52%). There was no difference in detection rates between African, American, and Caucasian subjects (p>0.3, Fisher‘s exact test). For specimens with detectable cannabinoids, concentrations ranged from 3.4 to >100 pg THC/mg, and from 0.10 to 7.3 pg THC-COOH/mg hair. THC and THC-COOH concentrations were positively correlated (r=0.38, p<0.01, Pearson‘s product moment correlation). Only about one-third of non-daily users and two-thirds of daily cannabis users gave rise to positive cannabinoid hair tests by GC/MS/MS, with detection limits of 1 and 0.1 ng/mg for THC and THC-COOH, respectively. All participants showed positive urine cannabinoid tests at the time of hair collection.

4. Conclusions

An understanding of human cannabinoid pharmacokinetics is important for the development and monitoring of new therapeutic medications and to the interpretation of cannabinoid test results in a wide variety of biological matrices, including blood, plasma, urine, oral fluid, sweat, and hair. With the advent of new preparations containing THC, CBD, and other cannabinoids, and new administration routes, additional research is needed. Also, controlled drug-administration studies that provide the scientific database for interpreting cannabinoid concentrations in biological fluids and tissues are increasingly difficult to conduct due to safety and ethical concerns, and because of the high costs of performing human research. However, these data are essential for appropriate application of pharmacotherapies, and for drug testing in treatment, workplace, and forensic cases.

Excretion patterns of THC in oral fluid and plasma, and urinary THC-COOH/creatinine levels in a human subject following smoking of a single cannabis cigarette containing 3.55% of THC. The THC-COOH/creatinine ratio is illustrated for all urine specimens collected through the last positive specimen. Analyses were performed by GC/MS at cutoff concentrations of 0.5 ng/ml for oral-fluid and plasma samples, and at 15 ng/ml for urine samples, resp. Reprinted and adapted with permission by Journal of Analytical Toxicology, p. 397 in [164], Fig. 2 .


1 Unless noted otherwise, THC always refers to the Δ 9 -variant.

2 Non-systematic compound names cited in the literature are used for the sake of clarity.

Marijuana seed interception increase

by Edward M. Brecher and the Editors of Consumer Reports Magazine, 1972

Chapter 59. The 1969 marijuana shortage and "Operation Intercept"

The extent of marijuana use and distribution in the United States was brought to nationwide attention in the spectacular failure of "Operation Intercept," an elaborate and determined effort by the government to shut off the flow of smuggled marijuana from Mexico. The program was based on the belief that Mexico was and would remain the primary source of marijuana for Americans.

Operation Intercept was launched at 2:30 P.m. Pacific Daylight Time on Sunday, September 21, 1969, and abandoned on October 11 –– just 20 days later. Felix Belair, Jr., broke the story two weeks in advance, in the New York Times under a September 8 dateline from Washington: "At the direction of President Nixon Federal enforcement agencies are preparing an all – out drive on the smuggling of drugs into the United States from Mexico. Details of the drive. are being kept a closely guarded secret pending a joint statement later this week by the Secretary of the Treasury and the Attorney General. In personnel and equipment it will be the nation’s largest peacetime search and seizure operation by civil authorities." 1 So important was the drive that President Nixon had discussed it at his September 8 meeting with President Gustavo Diaz Ordaz of Mexico. "On this side of the border pursuit planes and some motor torpedo boats will be employed for the first time. Additional observation planes will be placed at the disposal of a strengthened border patrol." Operation Intercept was to be concerned partly with heroin and other drugs –– but primary emphasis was to be placed on marijuana, the bulkiest of the drugs commonly smuggled and therefore the easiest to intercept.

The drive to close the American border was strategically timed for the September 1969 marijuana harvest. The American marijuana supply was already far short of the demand, and the closure was intended to intensify the shortage.

"Pot began to be scarce in June [1969]," Peggy J. Murrell explained in the, Wall Street Journal for September 11, 1969, "when Mexico started cracking down on shipments of the weed smuggled into the U.S." 2 A college sophomore named Frank, vacationing in New York City’s East Village, was quoted as saying: "Nobody can get any grass. After all this damned LSD, speed, and mescaline that’s going around, it sure would be great to act back to some nice, soft pot." Miss Murrell then explained:

"Frank had intended to stock up on marijuana in New York and take it to his friends at college, but the ‘pot drought’ has left him emptyhanded. ‘It’s really awful,’ he complains. ‘What will I tell the kids?’ "

A Wall Street Journal reporter had interviewed Larry Katz, head of the justice Department’s Bureau of Narcotics and Dangerous Drugs in San Diego, who explained that the summer marijuana shortage started in Mexico "because of a drought and a killing. Lack of summer rains thinned the grass [marijuana] crop. Then a Mexican official who had ordered the burning of 50 acres of what was left, was shot and killed. As a result of the killing, martial law has been declared. They have moved in troops for a house-to-house search throughout the state (of Sinaloa) and every road leading out of Mexico is heavily guarded. The Mexican government now maintains squads that constantly destroy marijuana wherever they find it." 3

Though the Wall Street Journal failed to mention it, the burgeoning demand for marijuana on the part of a rapidly growing mass of users was also no doubt a major factor in the midsummer 1969 "pot shortage." Supplies were lagging far behind demand –– at least temporarily.

"Far from rejoicing at the marijuana shortage," Miss Murrell’s Wall Street Journal dispatch continued, "some narcotics officials are now afraid that pot smokers may switch to other, more dangerous routes to euphoria." 4 One of these officials was William Durkin, head of the New York Bureau of Narcotics and Dangerous Drugs, who was quoted as saying: "Youthful drug experimenters, if they can’t get one kind of drug, will look for something else."

A twenty-one-year-old Radcliffe College senior interviewed by Miss Murrell emphatically confirmed this official view. "I really didn’t want to try acid (LSD) before," she was quoted as saying. "But there’s no grass around, so when somebody offered me some (LSD), I figured, ‘What the hell.’ I didn’t freak out or anything, so I’ve been tripping [taking LSD] ever since."

"The objective of the [Operation Intercept] program," Secretary of the Treasury David M. Kennedy and Attorney General John N. Mitchell declared in a joint statement released at precisely 2:30 P.m. on Sunday, September 21, 1969, "is to reduce the volume of narcotics, marijuana, and dangerous drugs which are smuggled into the United States from Mexico." 5 The statement added that "more than 80 percent of the marijuana smoked in the United States" entered the country illegally from Mexico. If this 80 percent could be cut off, all would be well. That, at least, was the official hope.

Traffic at the border "was backed up for more than two and a half miles within an hour after Operation Intercept began," Felix Belair, Jr., of the New York Times reported from San Ysidro, California, on September 21. "And as the usual Sunday exodus from the Tijuana bullfight and racetrack approached the border station in late afternoon, traffic was backed up for six miles" 6 in the border dust and heat. No doubt the officials who planned Operation Intercept had had this peak traffic flow in mind when they set 2:30 P.m. on Sunday afternoon as H-hour. By then a maximum number of Americans would have entered Mexico for the afternoon, and would be caught in the operation en route home.

Halted motorists "expressed their feeling in the classical manner" by blowing their horns. "They’re playing our song," a customs agent remarked.

Similar scenes, the Times dispatch continued, were "being enacted at the 30 other border-crossing stations along the 2,500-mile-long border between the two countries. In between, special radar installations have been set up by the Federal Aviation Administration to enable waiting customs agents to detect any attempt to cross the border unobserved.

Military pursuit planes borrowed from the Air Force were poised to chase any aircraft that failed to file a pre-flight plan before heading across the border.

The surveillance network was spread out to sea, with Navy boats plying the Gulf of Mexico and a variety of patrol craft in coastal waters. The "intensified inspection of vehicles and persons crossing the border" was in effect also at the 27 airports at which international flights are authorized to land. 7

"Despite complaints about zealous inspectors peeking into the purses and lunchboxes of school children and forcing travelers to strip for personal searches, the United States said today that it has been successful in its Mexican-border crackdown on drug smuggling," 8 said the lead on an Associated Press dispatch from Los Angeles on the eighth day of the operation. Although only small quantities of drugs bad been seized during the week, a federal spokesman was quoted as saying: "We’re measuring our success not by the quantity of seizures made but by the price of marijuana, heroin, and other drugs on the market. It is raising their cost beyond the means of most young people in America.

"We’re positive we’re stopping narcotics and dangerous drugs from coming into this country. No large seizures have been made since Intercept was launched last Sunday, because obviously the big smugglers have gotten the word." Obviously the small smugglers had also gotten the word. "We know we’re succeeding," the federal spokesman continued, "therefore we feel that most Americans will agree it is worth our effort, the manpower and expense involved." The New York Daily News ran the dispatch under the headline "GRASS CURTAIN A SUCCESS."

As might be expected, however, Operation Intercept engendered a number of protests. The earliest of these came from along both sides of the border.

"In the 30 twin cities that straddle the United States-Mexican border from here to the Gulf," Mr. Belair of the New York Times again reported from San Ysidro on the third day of the operation, "the government’s drive on marijuana smuggling has become one of the hottest issues since Pancho Villa raided frontier towns.

Commerce and tourism are grinding slowly to a halt. Retail business on the American side has dropped more than 50 percent. And with no relief in sight, the merchants are up in arms because Mexican customers won’t waste two to four hours waiting to go through customs inspection.

It’s the same in the cities and towns on the Mexican side that depend on weekend tourists and commuter shoppers.

Absenteeism is rampant among Mexican. workers with permits that allow them to live in Mexico and work in the United States. Mexican school children attending public and private schools in the United States have been showing up two to three hours late or don’t show up at all.

The impact of the operation hit like a windstorm at Chula Vista, the nearest shopping center to this major gateway. Chula Vista business establishments count on Mexican customers for about 70 percent of their trade. Yesterday, they catered to a handful of local customers. 9

On the second day of Operation Intercept, the dispatch continued, "the United Statcs-Mexican Border Cities Association decided to do something about it. It beaan organizing a protest, urging its 30 twin city members to get in touch with their Congressmen, governors, and mayors and demand a modification. " The head of the association also sent telegrams to all affiliated chambers of commerce on the United States side, warning that "time is short, and the need for action immediate." In a telephone interview he added: "The economic life’s blood of these communities is based on a free flow of vehicular and pedestrian traffic in both directions. Disrupt that flow, and the economy dies, people are thrown out of work and the communities will become ghost towns. "

On the seventh day of the operation, the New York Times reported from Mexico City:

Indignation mounted here yesterday in the press and business and government circles against the measures adopted by the United States in an antinarcotics drive on the Mexican border.

"Humiliating Mexicans" was the banner headline published by La Prensa, one of the largest newspapers in the country. It emphasized a theme that was echoed in many other dailies.

In the Chamber of Deputies, representatives of all parties protested vigorously against Operation Intercept on the border as a program that "damages the dignity of Mexicans and constitutes an unfriendly act. "

The National Confederation of Chambers of Commerce here termed the operation "an absurd and exaggerated program" for the meager results it has produced. 10

President Diaz of Mexico, who in early September had paid a courtesy visit to Washington during which his relations with President Nixon bad been cordial, in early October personally denounced Operation Intercept as "a bureaucratic error" that had "raised a wall of suspicion between Mexico and the United States." 11

The protest spread from Mexico to other Latin American countries. An ambassador from one such country, stationed in Mexico City, told a reporter: "It is the old story of United States policy decisions that affect a Latin-American country profoundly being taken for domestic political reasons without consultation or consideration." 12 Another ambassador likened Operation Intercept to the United States military intervention in the Dominican Republic in 1965.

Prior to Operation Intercept, border inspectors worked on a schedule that allowed them on the average one minute per vehicle crossing the border. During Operation Intercept, this quota was increased to an average of two or three minutes per vehicle –– hardly enough for a really thorough search. Further extending the duration of searches, of course, would have further extended the delays and the lines of cars.

Some persons desiring to enter the United States were required to strip to the skin for a personal inspection. Official reports revealed that during the first week of Operation Intercept 1,824 border crossers were stripped and searched. This left some 1,978,000 persons who had crossed the border with only a superficial search or none at all. Most of the 1,824 "skin searches," incidentally, proved fruitless; there were only 33 arrests along the border during the week. 13

"Ten days of relentless warfare on the smuggling of marijuana and dangerous drugs across the Mexican border has convinced United States enforcement officials of the futility of trying to dry up the illicit traffic with currently available money, manpower, and equipment," 14 Mr. Belair reported from San Ysidro on October 1. At that time nearly 2,000 agents and inspectors, including many transferred to the border from other posts, were at work in the operation.

"Attempts to get the drugs across border highway crossings concealed in motor vehicles have almost ceased. But enforcement officials say that illegal air traffic continues to move through the Mohawk Valley in Arizona, Laredo, Texas, and the rugged approaches to El Centro and San Diego, Calif.

"Meanwhile, with supplies of marijuana and dangerous drugs piling up south of the border as a result of the drive on land, Mexican distributors are changing smuggling methods. Checked at the normal crossing points, they have started to probe the fences along remote mountain trails and in the desolate flatlands where Mexican roads parallel the border by fewer than 100 yards." An undetermined amount of marijuana and other drugs was also being smuggled in by plane despite newly installed FAA radar equipment and Air Force intercept planes lent for the operation. "Recently positioned radar installations. showed the blips of intruding aircraft from the south but the blips faded from scanning screens as the planes dropped between mountain ranges and canyon corridors or passed beyond range of the truck mounted sensors." * 16

* This discovery by drug smugglers of the vulnerability of the United States Mexican border to aerial intrusion was to have disastrous aftereffects. Long after Operation Intercept itself was discontinued, aerial smugglers continued to use the techniques pioneered in September 1969.

"They fly low and slow, by the light of the moon, and make $50,000 a night," Robert Lindsey reported in the New York Times in November 1971." 15

"They use some private planes and old military transports and land on deserted airstrips or sagebrush-covered desert. Their cargo is marijuana, cocaine and heroin.

"Along the sparsely settled frontier that divides the United States and Mexico, airborne drug-runners are doing a booming business, and Federal agents say they do not know how to stop them.

"On most nights, the agents estimate, at least 10 planes cross the border with marijuana and other drugs. On rare occasions, the smugglers are caught by United States agents flying their own planes. But usually they land unnoticed. "

"Anybody who knows how to fly can get into the business and make a lot of money. one customs agent was quoted as saying; and an official of the Bureau of Narcotics and Dangerous Drugs added: "They’re developing their own air force, and it’s getting bigger and bigger."

Most of the planes used were small, but a Department of justice official noted that recently (November 1971), "a lot of them are starting to use bigger planes –– DC-3’s, surplus military transports, turbo-prop executive planes, and we have our eye on one group that has a Constellation."

A Constellation can carry twenty tons of cargo –– enough to supply the entire United States heroin market for three or four years with the fruits of a single flight.

Despite the fact that marijuana weighs far more than heroin per dose and sells for far less, it, too, can be profitably smuggled by air. The Department of justice official told reporter Lindsey bow "in the interior of Mexico, you can buy weed [marijuana] for as low as $2 a brick [2.2 pounds], but if you don’t know your way around, you will probably have to pay closer to $30. It doesn’t take a very big plane to fly 500 bricks if you take out the seats and strip it down.

"Say [a smuggler] buys it for $30 and sells it in the states for $130; that’s a profit on 500 bricks of $50,000 for a night’s work." At $130 per brick or kilogram, moreover, the cost per half-gram marijuana cigarette works out at 6.5 cents-hardly an exorbitant price, even at wholesale.

On October 8, 1969, a delegation of Mexican officials beaded by Mexican Attorney General David Rodriguez conferred in Washington with a delegation of American officials headed by United States Attorney General Mitchell. As late as the afternoon of October 9, after two full days of these talks, Mr. Belair reported from Washington to the New York Times that "the United States has rejected a Mexican government appeal for a prompt termination of Operation Intercept. A source close to the conferees said the United States had no intention of calling off the drive or of substantially modifying border inspections. " 17

But the next day, Operation Intercept was called off.

"In a dramatic overnight reversal of position," Mr. Belair announced under an October 10 dateline, "the United States bowed today to Mexican demands and ordered a strategic retreat in its war on the smuggling of marijuana and dangerous drugs into this country.

"A joint statement by representatives of both Governments after three days of conferences on Operation Intercept said it bad been superseded by Operation Cooperation. It added that the United States would ‘adjust’ its border inspection procedures ‘to eliminate unnecessary inconvenience, delay and irritation.’

"Precisely what happened to cause the about-face by United States delegates was not immediately clear and the Federal enforcement officials who are most concerned with the problem said they were ‘too sick to talk about it."’ Mr. Belair added, however, that State Department officials had first proposed the retreat, that justice Department officials had agreed; "this left the Treasury Department contingent under Assistant Secretary Eugene T. Rossides standing alone without White House support. As the showdown approached today, the White House, was advised of the pending decision but decided against any direct involvement." 18 Traffic across the border began flowing freely again on the next day –– Saturday, October 11.

"An immediate problem for enforcement officials," Mr. Belair added, was how to soften the impact of today’s retreat on the morale of customs agents and inspectors and members of the Border Patrol who have been working 12 and 14 hours a day to make Operation Intercept a success."

While primary responsibility for ending Operation Intercept was commonly attributed to the protest from Mexico, from the rest of Latin America, and from American border businessmen and their Congressmen, the statistics of drugs seized may also have played a role. During the year ending June 30, 1969, United States customs officials had seized 57,164 pounds of marijuana –– about 150 pounds per day. During the three weeks of Operation Intercept, they bad seized 3,202 pounds of marijuana –– about the same amount per day. 19 Operation Intercept had enormously inflated marijuana publicity, but had not increased marijuana seizures. How much smuggling increased elsewhere as a result of the transfer of customs officials and narcotics agents to the Mexican border is not known.

A statement by then Deputy Attorney General Richard G. Kleindienst and Assistant Secretary of the Treasury Eugene T. Rossides, released by the United States Department of justice twelve days after the termination of Operation Intercept, claimed a modest success. It described marijuana as "unavailable in Miami and almost unavailable in New York," as well as "almost unavailable at Yale, Harvard and the University of California [Berkeley and Los Angeles]. A similar or even more tight supply condition exists at the University of Chicago, Rice Institute, Oklahoma University, Southern Methodist University and Northwestern University." 20

This announcement from Washington evoked a bitter retort from Professor Charles R. Beye, chairman of the classics department at Boston University, who declared in a letter to the editor of the New York Times:

In their elation at having made marijuana scarcer on our college campuses, could the Federal narcotics agents ponder for a moment the ugly repercussions of their campaign?

Many dealers responding to this scarcity are blending in all kinds of other ingredients to provide strange psychic effects neither sought nor planned. The high price of marijuana is moving the high school crowd into some really weird trip-causing agents, of which glue is only the mildest.

The intensive police pressure reinforces the sense of being criminal and thus antisocial. Then, too, instead of your friendly student dealers, older men suspiciously criminal-looking, are beginning to push the pot; obviously the student amateurs are being closed out of the increasingly profitable marijuana business and organized crime is being given another avenue of exploitation.

As someone who spends a great deal of time with the young I must say that marijuana is here to stay. As a father I can only hope that these hypocritical, viciously unnatural laws and the people who enforce them are removed before an entire generation is perverted morally and corrupted physically. 21

Professor Beye’s concern that marijuana users deprived of marijuana might shift to other substances was confirmed in some detail in a study of what actually happened among Los Angeles marijuana smokers during Operation Intercept. The study was undertaken by two graduate students in psychology at the University of California at Los Angeles, Kay Jamison and Steven Rosenblatt, in collaboration with Dr. William H. McGlothlin of the UCLA psychology department. 22 Questionnaire returns were secured in this project from 478 UCLA undergraduate and graduate students, and from 116 patients attending the Los Angeles Free Clinic. The great majority of both the students and clinic patients were marijuana smokers who had smoked marijuana ten or more times.

One question which the study sought to answer was whether there had actually been a marijuana shortage before and during Operation Intercept –– a shortage sufficient to curtail marijuana use. Deputy Attorney General Kleindienst and Assistant Secretary of the Treasury Rossides, it will be recalled, had announced on October 23 that marijuana was "almost unavailable" at UCLA. The study did not bear this out. "Of those using marijuana ten or more times," the Los Angeles group reported, 44 percent of the students and 51 percent of patients reported that their frequency of marijuana use was below normal at some time between May and October 1969, as a consequence of the unavailability of marijuana." 23 The other half of the respondents were able to go right on smoking marijuana at their customary frequency despite the shortage that preceded Operation Intercept and despite Operation Intercept itself.

The respondents were also asked how much they bad been paying for marijuana in May 1969, and bow much in October 1969. The responses, when averaged, worked out to $10.13 per ounce in May and to $11.87 per ounce in October. About 60 half-gram marijuana cigarettes can be made from one ounce of marijuana. Thus the price as reported by Los Angeles smokers rose from about 16.9 cents per marijuana cigarette in May to about 19.8 cents in October. 24

Finally, the Los Angeles study sought to determine how the marijuana shortage affected the consumption of other drugs. "Of those reporting a shortage of marijuana," the UCLA researchers noted, "76 percent of students and 84 percent of patients reported that they increased their consumption of one or more other drugs (including alcohol) because of the unavailability of marijuana." 25 Here are the drugs to which these respondents turned as a result of the marijuana shortage. 26

Drug Students
Free Clinic
Male Female Male Female
(N = 56) (N = 30) (N = 24) (N = 25)
Hashish 52 37 54 44
Alcohol 55 23 50 48
Sedatives 9 10 29 24
Stimulants 11 7 21 16
LSD 16 7 50 48
Other Strong Hallucinogens 23 13 37 28
Opiates or Cocaine 2 3 25 24

The temporary shortage of Mexican marijuana led to a marked increase in the importation into the United States of highly potent marijuana from Vietnam. Some of it was mailed home through GI channels; far larger amounts were brought home by military personnel returning from the war. San Francisco observers reported a flood of Vietnamese marijuana on the market immediately following the docking of each homebound troopship. There were few prosecutions, however –– perhaps because officials did not welcome the political repercussions which might follow the large-scale criminal prosecution of veterans freshly returned from war.

Another effect of Operation Intercept was to open the United States for the first time to the large-scale importation of North African and Near Eastern hashish. There is a delicate balance between marijuana prices and hashish prices. Hashish is more costly to produce because it takes much more labor during the brief harvest period –– but it is easier to smuggle because a comparable dose weighs only one-fifth to one-eighth as much. Trivial amounts of hashish had long been available in the United States. The tight marijuana supply before and during Operation Intercept triggered a large-scale increase in hashish smuggling.

Numerous instances were cited in newspaper dispatches before, during, and after Operation Intercept: For example, the New York Times reported from Washington, D.C., on August 17, 1969, that "the smuggling of hashish, a concentrated form of marijuana, has sharply increased," according to Myles J. Ambrose, then Bureau of Customs Commissioner. Seizures for the year ending June 30, 1969, totaled 623 pounds –– "up from 311 pounds the previous year. Only about 70 pounds bad been seized in 1966 and 1967." Marijuana seizures did not increase. An assistant commissioner of customs cited three reasons for the rise in hashish smuggling: it is far less bulky than marijuana, it is highly potent, and it appeals to the "hippie type" of tourist. 27

On October 6, 1969, Sydney H. Schanberg reported in the New York Times from Srinagar, Kashmir, that Kashmiri hashish formerly went mostly to the Middle East. "But now," he quoted the local chief of police as saying, "there is a new market –– Europe and America. And therefore the price has gone very high." 28

On October 10, 1969, Dana Adams Schmidt reported in the New York Times from Beirut, Lebanon, that "eleven Americans are in prison in Lebanon on charges of using or trafficking in hashish." He went on to explain: "Two pounds of hashish selling here for $40 to $80 can be resold in the United States for that amount an ounce." 29

The Burlington, Vermont, Free Press reported on March 17, 1970, that hashish purchased for $3,000 in Ibiza, Spain, and alleged to be worth $350,000 in the United States market had been seized in Vermont after it had been shipped by freight from Ibiza to Casablanca, to Marseilles, to St. Thomas, Ontario, to Tonawanda, New York, and then to Rutland and Plainfield, Vermont. 30

Finally, the marijuana shortage induced many industrious people to spend more time harvesting domestic "weed" marijuana, growing throughout the United States.

Under ordinary circumstances, with high-quality Mexican marijuana available at moderate prices, there is relatively little incentive to harvest the domestic weed supply. The hourly wage rate is much higher in the United States than in Mexico, and harvesting marijuana takes time. When prices rise and supplies become scarce, however, people take to the harvest fields in large numbers, Edward B. Zuckerman described the marijuana-harvesting process in a dispatch from North Judson, Indiana, published in the Wall Street Journal of August 20, 1969:

The elderly farmer escorts a visitor around his prosperous-looking farm near this quiet northern Indiana town. There’s the corn field, he says, and there’s the potatoes. And over there is the marijuana.

The farmer hastens to point out that he doesn’t cultivate the marijuana, it just grows wild. Indeed, he considers it a headache. "It gets so thick around my storage lot that I have to pay good money to spray it so I can find my machinery," he says. "Then, I’m always shooing away people who come on my land to pick the stuff."

The farm is a typical one in this lush farming area not far from Chicago. The hardy marijuana plant. grows in weedlike abundance along roads and drainage ditches here. It’s difficult and expensive to kill, and it has made the region something of a mecca for enterprising devotees. who drive to the farmlands to help themselves rather than pay the $15 to $20 an ounce that processed marijuana brings on the clandestine market.

"We’ve arrested every type of individual –– white, colored, male, female, young and old –– a real cross-section of the population," says Sgt. Harry Young of the Indiana State Police, whose members regularly inspect cars parked along the roads near here.

Marijuana came to North Judson, as well as to other areas of the Midwest where it grows in abundance, as the upright and respectable hemp plant. Mills that converted the tough fibers of the plant’s stalk into rope used to dot the Midwest. Hemp cultivation has all but ceased in the U.S. but the plant hangs on. "It’s extremely hardy and adaptable we’ve seen it growing in sandy soil and in the most swampy areas," says University of Illinois botanist Alan W. Haney. "It’s also very bard to get rid of. It takes a high concentration of poison to do the job. I’ve seen plants that.wilted after being sprayed, but sprang back within two weeks." 31

By early November 1969, the marijuana famine was over –– in considerable part as a result of increased harvest of the domestic American " weed" supply. Reporter John Kifner supplied the details in a dispatch from Lawrence, Kansas, which appeared in the New York Times for November 7, 1969, less than a month after the abandonment of Operation Intercept:

Only a few of the plants –– 8 to 10 feet tall with clusters of seven sharply serrated leaves –– are still green. Most of the stalks are brown and withering after the first frosts.

Some harvesters, who contend that a field-dried crop yields the best product, are still gathering tops and leaves.

But much of the work –– the hurried chopping under the hot sun, the heaving of armsful of plants into automobile trunks and the stumbling around in the dark with flashlights and pillowcases to be filled –– has been done.

The last crop is hanging, upside down so the precious sap can flow into the leaves, in garages, backyards and dormitories waiting to be dried and processed. The harvesters are settling back and lighting up to enjoy the fruits of their labors.

The crop is marijuana, and this has been a good growing year, particularly here in the flat Middle Western plains, where the Cannabis sativa plant grows wild along the edges of fields, river banks and railroad tracks, and sometimes in cultivated plots.

"The marijuana has been like a super benefit to this community," a student at the University of Kansas said with a grin. "A lot of people have got new motorcycles and things because of it."

The director of the Kansas Department of Agriculture’s Noxious Weeds Division reported that there were 52,050 acres of marijuana in the state in 1968 –– the figure is probably higher this year. The plant is also growing in wild profusion throughout Nebraska, Iowa and Illinois.

It is a strong and hardy plant that resists efforts at eradication by fire or chemicals, to the delight of the young and the distress of the law enforcement officials and politicians.

In Indiana, farmers complain of the difficulty of clearing the plant from the edges of their fields. According to underground sources, an elderly farmer in the Champaign-Urbana area, near the University of Illinois, has simply let a field go to marijuana.

He sits in his farmhouse with field glasses, these sources say, waiting for youths to come and pick the crop. Then he calls the police and collects an informer’s fee.

While the Middle West is the main center for wild marijuana, the plant is being harvested more and more secretly in small cultivated patches throughout the country.

In Vermont, the state police say there are vast quantities of marijuana growing wild in the Champlain Valley and being regularly harvested at night.

Policemen destroyed tons of marijuana over the summer months, but the crop was too big for the available manpower and equipment.

Detective Cpl. William Chilton said he believed the quality of Vermont marijuana was almost as good as that of most of the Mexican varieties.

There are scattered fields throughout Georgia, including a patch in the Okefenokee Swamp, and Joseph Weldy, the state’s chief drug inspector, said he expected to find "a lot of marijuana fields in the spring."

In Austin, Tex., marijuana has been found growing on the State Capitol grounds and at the municipal golf course. Crafty planters frequently sow their crop on public ground, where it will be well-tended by unsuspecting gardeners.

In Oregon, state agents had 3,000 plants under surveillance in the Cornelius Pass west of Portland last August. They were thwarted when an industrious Washington County lawman destroyed the plants with chemicals. There was a lack of communication, officials said.

Law enforcement and underground sources agree that the domestic marijuana harvest this summer and fall was probably the biggest yet. It was centered largely in the Middle West and particularly in Kansas.

The reasons for this, they agreed, are the shortage of Mexican marijuana, caused by Operation Intercept and other American pressures on the Mexican Government, and the rapidly increasing numbers of marijuana smokers.

The harvesting season runs generally from July to late October, with September the prime time. Throughout these months, hundreds of young people have been busily working in isolated fields, and rural sheriffs have been just as busily responding to calls from farmers reporting "a bunch of hippies in the fields" acting strangely.

Melwyn Purdy, an agent of the campus Bureau of Investigation here who is assigned to narcotics problems said there were 175 arrests for marijuana harvesting in this state since July 4. Last year, there had been about 40 arrests.

He described those arrested as "mostly young subjects, of college age with no criminal background."

Some of those arrested, Mr. Purdy said, bad road maps or hand-sketched charts showing where patches of marijuana might be found. Some of the areas of heaviest growth, he added, are along the Republican River in north central Kansas and in the eastern part of the state.

Gov. Robert Docking has expressed alarm at the situation, particularly at the possibility that organized crime might be moving into Kansas. Farmers, however, are not enthusiastic about the Governor’s plan to put marijuana under the weed control program since they would have to undergo the trouble of eradicating it from their own lands. Some conservationists and ecologists have expressed alarm at the potential destruction of ground cover.

A more powerful lobby –– hunters and sportsmen –– is also worried about the program. Quail feed on marijuana seeds, and organized hunters fear that a favorite quarry will be reduced in number.

The increase in the marijuana market has led to shady business practices. Kansas marijuana is being wrapped in Mexican newspapers and sent to California masquerading as the imported variety.

Most smokers seem to feel that Kansas marijuana is better than none at all, so the young people in and around Lawrence seem particularly happy about this year’s crop. 32

Another report, perhaps apocryphal, says that there was too much marijuana growing in Kansas in 1969; hence "the professional pot harvesters there have formed an association in violation of the Sherman AntiTrust Act to maintain price levels by destroying part of the crop." 33

The United States House of Representatives’ Select Committee on Crime in the fall of 1969 took an interest in this harvesting of domestic weed marijuana to supplement and perhaps replace imported Mexican marijuana. One witness it called was Lieutenant Wayne F. Rowe of the Nebraska State Highway Patrol; Lieutenant Rowe was questioned by Larry Reida, the Select Committee’s associate chief counsel, and by Congressmen Claude Pepper of Florida, the committee chairman, and Robert V. Denney of Nebraska.

Mr. Reida. Mr. Rowe, could you make an estimate, based on your information and experience in the field of marijuana control for the last couple of years, as to the number of acres of marijuana in Nebraska?

Mr. Rowe. No, sir, I couldn’t make this estimate. We had a discussion group yesterday. The experts said it was considerable.

Mr. Reida. We are talking about thousands of acres, right?

Mr. Rowe. Right.

Mr. Denney. We heard one estimate of 156,000 acres in Nebraska, right?

Mr. Denney. Yes, we did.

Mr. Reida. As a matter of fact, it grows in clumps; you don’t have a 100-acre field of marijuana.

Mr. Rowe. No, sir. You may find one plant on an acre and in other fields the entire field would be infested.

This "weed" marijuana, Lieutenant Rowe continued, was attracting "hempleggers" from all over the country:

Now, last year was the first year that we had a great deal of experience with marijuana harvesters coming in from out of State. In the year of 1968 we documented 40 arrests for marijuana harvesting. These were all people from out of State.

To date in 1969 we have documented 81 arrests of people from outside of Nebraska who have come in to harvest the marijuana that is growing here. This represents over a 100-percent increase over last year.

Mr. Pepper. How many arrests have you made?

Mr. Rowe. I have a breakdown in States: 32 arrests of California residents, six arrests of New York residents, six arrests of Massachusetts residents, five New Mexico, five from Washington, four from Virginia, three from Pennsylvania, three from Wyoming, three from Colorado, two from Michigan, two from Kansas, two from Utah, one from Ohio, one from Wisconsin, one from Arizona, one from Iowa, one from Oregon, one from Idaho, one from Montana, and one from Oklahoma.

Mr. Pepper. Did you notice that those arrests increased as the supply of marijuana coming into this country was diminished?

Mr. Rowe. Yes, sir. The spring crop of marijuana in Mexico, * as I understand it, was bad because of the weather. They were unable to dry it out. We also understand from the people whom we have apprehended that Mexican marijuana is not available in supply as is demanded by the present market.

* In Mexico, the same field may yield three or even four crops of marijuana per year.

Mr. Pepper. From that experience, would you anticipate that if we are successful in our effort to diminish the available quantity of marijuana in other parts of the country, there will be greater effort to get it from Nebraska and Iowa than there is today?

Mr. Rowe. Yes, sir, this will be what will happen. By coming to Nebraska they eliminate the dangers of crossing an international border. 34

The way in which Nebraskan and other Midwestern marijuana is subsequently distributed throughout the United States was indicated in an Associated Press dispatch from Freeport, Long Island, New York, dated October 4, 1970:

Five men were arrested here today in a raid in which police confiscated 300 pounds of marijuana said to be worth $600,000 at retail.

According to Nassau County and Freeport police, three of the men had driven from California in a panel truck, stopping on the way in Frank, Neb., to harvest a crop of marijuana they knew was growing in an open field there. Using machetes, the men cut enough marijuana to fill 15 duffle bags, the police said. 35

The three were identified as a twenty-four-year-old unemployed highschool teacher, a twenty-four-year-old professor at an unaccredited California college, and a twenty-eight-year-old student at a state university.

The suggestion that 300 pounds of weed marijuana, requiring only a machete for harvesting and a panel truck for transportation, would yield $600,000 for a few days’ work was obviously grossly exaggerated –– but the influence of such police estimates in attracting additional entrepreneurs to marijuana harvesting and distribution should not be underestimated.

Clandestine marijuana plantations have also made their appearance on a modest scale.

Not only is clandestine pot farming being carried on all over the country, [columnist Nicholas von Hoffman reported in the Washington Post] but many people are at work developing higher yields, more potent strains so that good quality grass should be increasingly available at moderate prices. In addition to the thousands who’re in this new industry for profit, there appears to be tens of thousands who grow pot at home for their own use. It’s an indomitably hardy vegetable that grows anywhere, even in closets or basements People plant it [indoors] in flower pots, train an electric light on it and wait for the high harvest. 36

Mr. Zuckerman’s August 1969 dispatch to the Wall Street Journal, quoted earlier, similarly reported that "some intrepid users have taken to growing the stuff on their own." He cited as an example a twenty-year-old college student who lived with his family in a Detroit suburb and who had cultivated a small crop in his family’s garden each summer since he was seventeen.

"Every year I tell my mother I’m growing gourds, and every year when there aren’t any gourds I tell her that I planted them late or something," the student was quoted as saying. He worried a bit when he saw his father in the marijuana patch –– "but it was all right. He’d very considerately put stakes on my plants and tied them for Support." 37

Once the plants are grown and harvested, the Wall Street Journal dispatch continued, this student "speeds the drying process by tying his leaves in a pillowcase and running them through the clothes dryer." The student was quoted as explaining: "At the end of the summer, you’ll usually find two or three of my friends waiting for their pillowcases" at a nearby launderette. This home-grown marijuana development resembles in several respects the home fermenting of grapes, the home brewing of beer, and the manufacture of gin in home bathtubs during Prohibition (1920-1933).

"Other amateurs," the Wall Street Journal added, "go in for marijuana cultivation in a bigger way. A hip young farmer in upstate New York, where wild marijuana is scarce and local police are less vigilant, is raising 500 plants for his friends in New York City. ‘Why should they pay for the stuff, when I can grow it so easily?’ he says."

An observer living in one New England township, formerly an agricultural center, says that marijuana is beginning there to take the place of other cash crops no longer profitable. "The only farms yielding a profit in our entire township are the three marijuana plantations." 38

The chief problem in growing marijuana secretly, either outdoors or indoors, is the excessive height of the plant –– often eight to ten feet at harvest time, and sometimes even higher. This height, of course, is the result of the fact that for so many hundreds of years seed from the tallest plants was selected in order to ensure long hemp fibers. just as clandestine chemists have been turning out drugs in kitchen laboratories, however, so clandestine geneticists and horticulturists are already at work developing a shorter marijuana –– less conspicuous to the police if grown outdoors and taking up less space indoors. Success should be fairly rapid; a marijuana strain growing only three to four feet tall has already been reported in London. 39

Clandestine synthesis of THC is another potential development. A group of young underground chemists in London, indeed, has already succeeded in synthesizing a small quantity of an impure THC, which they proudly smoked in front of BBC television cameras. 40 It is almost certainly the relatively low price and relatively ready availability of natural marijuana and hashish that have to date discouraged further development of clandestine synthetic THC. If prices rise high enough, or marijuana and hashish become scarce enough, that curb on THC synthesis and distribution will no longer function.

Chapter 59

1. New York Times, September 9, 1969.

2. Peggy J. Murrell, Wall Street Journal, September 11, 1969.

5. New York Times, September 22, 1969.

8. New York Daily News, September 29, 1969.

9. New York Times, September 25, 1969.

10. New York Times, September 28, 1969.

11. New York Times, October 10, 1969.

12. New York Times, October 8, 1969.

13. New York Daily News, September 29, 1969,

14. New York Times, October 2, 1969.

15. Robert Lindsey in the New York Times, November 30, 1971.

16. New York Times, October 2, 1969.

17. New York Times, October 10, 1969.

18. New York Times, October 11, 1969.

19. Robert Berrellez, Associated Press, in the Reporter Dispatch, White Plains, N.Y., October 1, 1969.

20. New York Times, October 24, 1969.

21. Charles R. Beye, Letter to the Editor, New York Times, October 30, 1969.

22. W. McGlothlin, K. Jamison, and S. Rosenblatt, "Marijuana and the Use of Other Drugs," Nature (London), 228 (December 19, 1970): 1227-1229.

27. New York Times, August 18, 1969.

28. New York Times, October 6, 1969.

29. New York Times, October 10, 1969.

30. Burlington, Vt., Free Press, ‘March 17, 1970.

31. Edward B. Zuckerman in the Wall Street Journal, August 20, 1969.

32. New York Times, November 7, 1969.

33. Nicholas von Hoffman in the Washington Post Star, August 12, 1970.

Measuring Illicit Cannabis Seizures in Canada
Methods, Practices and Recommendations

The measurement of illicit cannabis seizures in Canada was not previously studied in detail. Measuring seizures is important because the data can be analyzed to develop an understanding of many areas of cannabis regulation and enforcement—from trends in criminal methods or enforcement efficiency, to the size and value of illicit markets. This report examines the current methods of measuring the metric of cannabis seizures in Canada, with particular attention paid to the way seizure information is recorded by law enforcement officials. A discussion of potential improvements to the way Canada currently measures the metric of cannabis seizures is presented, including a critical review of which analyses could be undertaken if improvements to seizure reporting were introduced.

Author’s Note

The views expressed are those of the authors and do not necessarily reflect those of Public Safety Canada. Correspondence concerning this report should be addressed to:

Research Division, Public Safety Canada
340 Laurier Avenue West
Ottawa, Ontario, K1A 0P8
Email: [email protected]


The authors would like to thank the members of the Marijuana Data Working Group (MDWG) for their insightful comments on the statement of work for this project. The authors are grateful to colleagues from the Canada Borders Services Agency (CBSA), Royal Canadian Mounted Police (RCMP), Health Canada (HC), Public Safety Canada (PS), the Canadian Police College (CPC), and Criminal Intelligence Service Canada (CISC) for taking the time to meet with the authors and share their insightful ideas on cannabis seizures. Finally, the authors are grateful to the Canadian Centre for Justice Statistics (CCJS) colleagues Chris Munch and Rebecca Kong for their assistance in the collection and interpretation of information on police-related cannabis policy metrics.


The Minister of Public Safety and Emergency Preparedness Canada was tasked by the Prime Minister in 2016 to "work with the Minister of Justice and the Minister of Health on efforts that will lead to the legalization and regulation of marijuana" (Canada 2016). In support of this commitment, researchers from Public Safety Canada have recently completed a report titled "Cannabis Performance Metrics for Policy Consideration: What do we Need to Measure?" (Maslov et al., 2016). In it, the authors identified some 45 cannabis policy metrics on which policy makers could consider collecting baseline data prior to any shift in policy on marijuana. Collection of baseline data is important because it allows researchers and policy makers to examine the impact of policy through comparing pre- and post-policy data to further inform decision-making.

The Taskforce on Marijuana Legalization and Regulation completed a Discussion Paper on the Legalization, Regulation and Restriction of Access to Marijuana, which outlines that the design and implementation of a new regime for marijuana legalization and regulation requires careful attention to a number of particularly challenging issues grouped into five themes: minimizing harms of use; establishing a safe and responsible production system; designing an appropriate distribution system; enforcing public safety and protection; and, accessing marijuana for medical purposes.

Cannabis Footnote 1 is the number one cultivated, produced, trafficked, and consumed illicit drug worldwide (United Nations Office on Drugs and Crime (UNODC), 2016). The most recent data from the World Drug Report (UNODC, 2016: 43) states that North America accounts for 37% of seized cannabis herb globally. Most countries around the world consider cannabis to be an illegal substance, though there have been recent shifts in several countries to allow for various forms of use for medicinal, religious, or personal use to be decriminalized or legalized. In Canada, the act of possessing, producing, distributing, and trafficking of cannabis remains an offence under the Criminal Code until legislation that stipulates otherwise is passed in the House of Commons. Thus, from the perspective of the criminal justice system, cannabis remains illegal. It is listed as a Schedule II illicit substance under the Controlled Drugs and Substances Act (CDSA)(see Appendix A), and is seized by law enforcement as contraband.

Whenever there is a change in policy, it is important to collect information on metrics that will be used by researchers and policy makers to examine the impact of the policy. Legalization of the recreational use of cannabis is a historic policy change for Canada. It is vitally important to create a regime of data collection pre- and post-legalization in order to determine what impact the regime change has had on society. In the example of State of Colorado, where the recreational use of cannabis was legalized in 2012 and the full implementation of the policy occurred in 2014, very little data was collected pre-legalization as well as some time after the legalization (Police Foundation, 2015: 9). While much more attention is being paid to the collection of data in Colorado after the legalization, there exists a wide data gap that does not allow for the comparison of post- to pre-legalization metrics.

Illicit cannabis seizures was brought up as an important concept in Maslov et al. (2016), and one that needs to be examined in much more detail because this source of data can contribute to the development of an array of other cannabis policy metrics. These include metrics to quantify: diversion between markets and exportation across borders; the use of particular shipment methods, such as the postal service; trends in the potency of cannabis; and the effectiveness of efforts to eradicate illicit supply and trafficking. Seizure data can potentially be used to measure metrics in each of these areas, and were all identified as metrics on which it is essential to collect baseline data in Canada (Maslov et al., 2016: 21-22) prior to legalization. The authors discussed how the metrics are currently being measured. They also brought the readers’ attention to the current existing statistics on these metrics. Some constructive criticism of the way the metrics are currently measured was also offered.

Measuring illicit cannabis seizures is an important element in understanding the illicit drug market. Data on all of these metrics can be collected through proper measurement of cannabis seizures. Properly measuring these metrics would help explain how efficient law enforcement is at eliminating illicitly-produced cannabis products, or the domestic and international trafficking of cannabis through various means.


The objective of this project is to examine the current methods of measuring the metric of cannabis seizures with particular attention paid to the way seizure information is recorded by law enforcement as well as to discuss the potential improvements to the way we currently measure the metric of cannabis seizures. In particular, this project will be a critical review of what valuable information could potentially be gathered from seizure reports if improvements were introduced.


The report titled "Cannabis Performance Metrics for Policy Consideration: What do we Need to Measure?" (Maslov et al., 2016) served as a background paper to the current project. The sections on Diversion to Other Jurisdictions; Transfer Using Parcel Services; Exportation across Borders; Potency; and Eradication were used as a starting point and were expanded upon with additional literature and further insightful critical assessment of the metrics.

The project involved a thorough literature review and examination of the relevant performance metrics that can be applied to the upcoming legalization of the non-medical use of cannabis. The literature that was considered for examination consisted of academic published material, documents originating from governments and law enforcement agencies, and grey literature such as newspaper articles and non-academic discussion pieces in OECD countries. Furthermore, relevant course material literature from the Canadian Police Knowledge Network (CPKN) and the Canadian Police College (CPC) was consulted. A literature sorting strategy consisting of a "literature grid" that was used in Maslov et al. (2016) was applied in the current project. Upon gathering, sorting and analyzing the literature, a critical discussion of the cannabis seizure metric for which the literature was available took place.

Further to the thorough literature review, the results of the consultations led by the Canadian Centre for Justice Statistics (CCJS) with the members of the Canadian Association of Chiefs of Police (CACP) Police Information and Statistics (POLIS) Committee on cannabis-related metrics that are possible to collect through police jurisdictions in Canada was used for the purpose of discussion and analysis. Overall, 11 of 17 police services invited to participate provided a submission. Moreover, attempts to consult experts in relevant fields were made. This resulted in consultations with Royal Canadian Mounted Police (RCMP) and Canada Border Services Agency (CBSA) colleagues who are either performing the seizures themselves, or work in the research and policy areas relevant to seizures; Health Canada colleagues who have expertise in cannabis seizures and the specifics of the functioning of Drug Analysis Service (DAS) laboratories; CPC instructors who teach the courses on drug investigative techniques; and with Public Safety Canada (PS) policy colleagues who are working with the RCMP units who perform seizures of cannabis.

Definitions and Sources

Cannabis and Seizures

Cannabis and its by-products exist in several forms. The commonly-reported types of cannabis that are seized by the RCMP (RCMP, 2015a) are 1) cannabis (marijuana); 2) cannabis resin (hash); 3) cannabis resin (hash oil); and 4) cannabis (marijuana) plants. Other forms of cannabis may include cannabis-infused edible food products and drinks; tinctures and creams crystalized resins and waxes; viable seeds and cuttings; as well as pills and capsules (Lawrence, 2016). However, these are not included as separate types in the RCMP’s list of seized cannabis products because either the amount of seized products is less than 3kg, 1L, or 125 tablets/capsules, or the frequency of the seizures of these products is negligible.

Cannabis seizures may come about as the result of law enforcement investigations, actions, and reports at the federal, provincial and municipal level of enforcement. The act of law enforcement taking possession of an illicit substance may be understood as a seizure. Seizures can occur and be reported in a variety of ways: by weight (kg), by volume (L), or by numerical quantity (especially in plants). Below are examples of how the cannabis seizure is reported by the RCMP in the 2015 National Drug Seizure report (RCMP, 2015a):

  1. seizures measured by weight of cannabis: 8,906 occurrences; 1,771 kg; $13,300,000 value;
  2. seizures measured by volume of cannabis: 10 occurrences; 983 L; $2,000 value; and
  3. seizures counted by quantity of cannabis products: 104 occurrences; 1,668 tablets/capsules; $11,000 value.

Reports and Databases

There are four main databases in Canada that contain the information needed to supply data required for a proper measurement of seizure-based metrics. These databases are described below, in no particular order of importance, and will be referred to throughout this paper. Each of these databases has been established for operational purposes. None of the data is currently available to the public either in raw, anonymized, or aggregated forms. The release of detailed data is usually restricted in order to ensure the integrity of ongoing investigations, as well as to maintain the effectiveness of investigative methods and practices.

  1. Integrated Customs Enforcement System (ICES) Database. This database is used by the CBSA and provides valuable information on cannabis seizures that take place at Canada’s points of entry, including land border offices, international mail processing centres, and a number of other service locations. Among others, it includes variables such as: the date and time of occurrence of the seizure; status of the seizure; the substances seized separated by type, category, quantities seized, and estimated value. The full list of fields collected in the ICES database can be found in Appendix B.
  2. Controlled Drugs and Substances Database (CDSD). This database is used by HC. Whenever law enforcement performs a seizure of cannabis or other substances that are listed in the CDSA, they report on the seizure using the HC/SC 3515 form. The information on the seizures is sent to HC and entered into the CDSD. The database does not contain definitions for how cannabis seizures are valued or measured. The variables provided include the date and time of occurrence of the seizure, the type, generic name, drug name, strength (potency) and quantities seized. It also includes information on the number of requests for destruction of seized drugs. As such, it could potentially include the most accurate data on seized cannabis because all seized cannabis should be destroyed. Cannabis plants may be destroyed before charges are laid; however, dried cannabis and seed may be destroyed after the investigation is completed, the conclusion of the court case, or after 60 days (CDSA, 1996). The level of detail of information on the seizure is determined by the reporting officer. The full list of fields collected in the CDSD can be found in Appendix C.
  3. Laboratory Information Management System (LIMS). This database is used by HC’s Drug Analysis Service (DAS) to record information on cannabis sample exhibits from seizures that are part of the evidence of investigations and court procedures. The database includes information on a chemical analysis of the seized drugs to indicate the presence of cannabis, but does not include information on the quantity seized. The full list of fields collected in the LIMS database that are used for reporting on the substances found in the exhibits can be found in Appendix D.
  4. RCMP’s Records Management System (RMS). "RMS" refers to the general database for the recording and reporting on criminal incidents used by law enforcement jurisdictions. As such, each police service tailors and modifies "RMS" software to meet their unique needs (Brooks, 2014). "RMS" systems often are also specifically used to record cannabis seizure occurrences. There are two main software vendors creating these systems for Canadian police services: Niche and Versaterm. The RCMP RMS (referred to hereafter as RMS) system consists of three databases: the Police Reporting and Occurrence System (PROS); BC PRIME and Halifax Versadex. The RCMP uses drug seizure information from their RMS databases to report annually on the overall seizures of illegal drugs in Canada. While individual data sets are not available to the public, RCMP data at the national and divisional level is published in the form of a National Drug Seizure (NDS) report (RCMP, 2015a). Footnote 2 RMS includes variables that include data on the type, value, quantity, and form of the seized drug; and details on the seizing procedure by law enforcement. The full list of fields collected in the RMS database can be found in Appendix E.

Measuring Seizures

As a Schedule II illicit substance under the CDSA, cannabis seizures only require reasonable grounds to believe that any controlled substance is present. Cannabis can be seized at any point between its production and consumption, including during transportation, exchange, cultivation, or while it is in the presence of any individual who is not authorized to possess it. Points along this spectrum of cannabis possession are governed by different enforcement authorities, which seize cannabis under their jurisdiction and mandate. As a result, there are several databases in Canada that record cannabis seizures under different mandates, including CBSA’s ICES, HC’s CDSD and LIMS, and the RCMP’s RMS databases. Multiple data collection points for measuring cannabis seizures are beneficial in developing a deeper understanding of the context of the cannabis market in Canada. Sources of data are collected and maintained by three key public safety partners and are tailored to meet their operational and data needs: individual police services (including the RCMP), CBSA, and HC. Additionally, this data and internal intelligence is used by PS for policy work related to cannabis legislation. Given the level of resources required to collect data of value for each organization, data collection is generally limited to the data areas that provide the performance indicators necessary to carry out their own particular mandate.

Consulting data from all seizure data points allows for more informed decision-making with appropriate models of the cannabis market in Canada. Comparison across the data sources allows for wider and more comprehensive analysis, but requires data to be reliable and comparable across data sources. Unfortunately, it is often the case that data from the same source may change over time, as the definitions or parameters for the data field evolve over time, or as policing priorities change. Footnote 3

In Canada, the Narcotics Drug Act Amendment Bill made it illegal to possess cannabis in 1923. The Controlled Drugs and Substances Act (CDSA) is the current legislation making the possession of cannabis for non-medical cannabis illegal. In 1999, legal access to dried marijuana for medical purposes was established (Health Canada, 2016a). In R. v. Parker it was interpreted that individuals with medical need had the right to possess cannabis for medical purposes. Under the current cannabis regulation regime, cannabis that is not possessed for medical purposes is still deemed to be illicit. The CDSA outlines powers of state for enforcing the possession of illegal drugs, as well as outlining what is included as a Schedule II drug (see Appendix A). There have also been a number of cannabis strains that have been added or repealed over time, changing what forms of cannabis or cannabis products were to be deemed legal or illegal.

In Allard v. Canada, the Federal Court struck down rules that prohibited Canadian medical marijuana patients from growing a "limited" amount of their own cannabis, or have someone grow it for them (CBC 2016). Following this ruling, the CDSA was updated to include the Access to Cannabis for Medical Purposes Regulations (ACMPR). The ACMPR regulates legal access to cannabis for medical purposes.

Over time, data collection methods have evolved to capture information on cannabis seizures in several areas in public administration. Specific to their context, it is important that analysis of cannabis seizure metrics takes into account these changes when making inferences and undertaking analyses. Depending on the nature of the evolution, certain trends may not be actually indicative of changes in consumption, production, or distribution patterns, but be more reflective of shifting operational tactics, data collection policies, or level of enforcement efforts.

The primary departments and agencies that were identified as sources for cannabis seizure metrics are: RCMP, CBSA, and HC. PS was identified among users of cannabis seizure metrics. Data on cannabis seizures collected by these different departments and agencies provide different types of information to tackle the issue from the perspective of the responsibilities as set out in their organizational mandates.

Illicit drugs have significant links with organized crime, both nationally and transnationally (World Drug Report, 2016). How organized crime groups operate to profit from the movement of illegal cannabis within Canada is important for policy considerations. Additionally, attention must also be given to cannabis that originated outside of Canadian borders. It is often challenging to identify the originating source of cannabis production, without conducting an extensive investigation. Limited geographic source information for seizures at ports of entry does exist, but may not be representative of the drug situation in Canada.

The RCMP and CBSA are sometimes asked to participate in international cannabis investigations, where the investigations have ties to Canada. These "assistance files" include limited access to international cannabis data or reports. This data and information are spotty and not regularly recorded in databases by either organization. Even with its closest neighbour, Canada and the United States have limited information sharing or access to data on seized cannabis crossing this border.

Canada Border Services Agency

The CBSA is responsible for Canada’s borders, "ensure[ing] the security and prosperity of Canada by managing the access of people and goods to and from Canada" (CBSA, 2016a). This includes the prevention of illicit drugs and precursor chemicals from being smuggled across Canada’s borders. Seizure of illegal drugs is included within CBSA’s mandate but is not their top priority.

One of the key pieces of legislation that govern the CBSA is the Customs Act, which CBSA is responsible for enforcing. The Customs Act outlines the authorities for CBSA in respect to regulating goods being imported or exported across Canadian borders. As CBSA operations center on regulating imported goods, operations for exports lack both the funding and process to operate in the same manner. Powers are limited in regards to exported goods, which generally limits the CBSA to seizing cannabis that is imported into Canada at the ports of entry. However, it is important to note the metric of export and import seizures are not currently captured in ICES. While the data is primarily import-related, it does not directly currently distinguish between import and export data; however, it is possible through data manipulation using point of origin.

The majority of CBSA’s cannabis seizures are small or personal seizures, though there are occasional larger seizures that take place. The threshold where the RCMP requests law enforcement partners to refer a seizure of any illicit drug for investigation is either 3 kg, 1 L, or 125 tablets/capsules, depending on the unit of measurement used to record the seizure (RCMP, 2015a).

The Customs Act provides CBSA officers with the authority to examine individuals or goods crossing the Canadian border at one of Canada’s ports of entry and seize any goods where the officer has reasonable grounds to believe that the Customs Act or its regulations have been contravened. The examination authority is exercised on a no-threshold basis for goods that have been imported but not yet released by the CBSA, with the exception of "any mail that is being imported or exported and that weighs thirty grams or less" that does not have the consent of the sender or addressee to open it (Customs Act, s. 99(2)(3), 1985). Confirmation of suspected cannabis is often done through a combination of visual and scent identification of common drug characteristics, as well as simple field tests that identify signature chemicals. Upon successful identification of cannabis, officers are authorized to seize the cannabis, and record the seizure in ICES.

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In the event that officers are unable to positively confirm the presence of cannabis, or require additional analysis to identify suspected drugs, the sample can be sent to the CBSA laboratory for further testing. The CBSA laboratory tests to detect the presence of cannabis, but does not do additional analysis regarding the potency, purity, or strain of the cannabis without additional authorization. In the event that a cannabis seizure is being investigated or a formal charge is going to be laid, samples of the cannabis are then sent to DAS for certification.

Cannabis is categorized by the CBSA officers conducting the seizure. While most cannabis seizures are fairly straightforward, it is possible that the seizure does not fit neatly within the four pre-identified cannabis categories (cannabis, hashish, hashish oil, plants). Current best practices are to include as many details as possible in the cannabis seizure report, though this is often included as notes or attachments to the metrics that are included within the various seizure databases. Emerging forms of cannabis concentrates, including wax or shatter, cannot be recorded directly, unless data collection includes officer field notes. These forms of cannabis have distinct compositions and may vary in terms of potency and estimated value. The CBSA has made efforts to identify a procedure for properly recording some emerging forms of cannabis; more guidance and a systems update is needed.

Seizure measurements may vary, depending on the level of concealment material included in the calculation. These measurements may include other material that is not cannabis, including packaging such as plastic or glass containers as well as non-useable parts of the cannabis plant (such as the stem, leaves, etc.). The CBSA established best practice is to remove the cannabis from the concealment material and measure the cannabis separately. While this method works most forms of cannabis, it is not operationally possible to extract cannabis from cannabis infused products. Cannabis infused products introduces material in the measurement which is not included within the amount of seized cannabis. These details may be included in the seizure narrative (an open text variable), but are inexact and should be interpreted with caution. The measured amount of raw plant material or pure solids extracts is reported to be the most accurately measured types of cannabis products, with instances of less accurate amounts being measured for liquid cannabis products, and significantly less accuracy when it comes to infused and mixed products, particularly what are termed edibles. The amount of cannabis in infused and mixed products is far less than the actual amount of the product itself, though CBSA officers have been known to weigh the product as a whole. As more cannabis infused products enter the market, a false inflation of the data may occur, skewing this metric. Currently, there is no guidance on how to more accurately capture measurements or report seizure amount when non-cannabis material is included.

Despite recognizing that the measurement of seized cannabis may not be exact or may be significantly inflated, CBSA officials must consider the costs and benefits to investigate and report more accurate measurements. The process for seizures is already time-consuming for CBSA officers, and additional investigation would increase the amount of resources required to complete each case.

Cannabis may also be seized by the CBSA in plant form. In reporting these seizures, CBSA officers count and report on the number of individual plants seized. CBSA officers do not report on features of seized cannabis plants that can affect the value or amount of seized cannabis. For example, reports do not require officers to differentiate between seedlings and mature plants, plant strain, or amount of useable cannabis in recording the number of plants seized. Instead, all cannabis plants seized are counted and reported on as if they were equivalent to each other.

ICES also includes a field for the estimated value of seized cannabis, which may be useful for analysis. Cannabis values are automatically recorded at "street value," based on the system-calculated, per gram price of the seized product. The CBSA has limited involvement in determining the pricing list values. The value field in ICES is automatically calculated using the seizure information reported by CBSA officers. Most recently, these values were calculated using price lists that were provided by the Criminal Intelligence Service of Canada (CISC), though this role was previously held by the RCMP. This price list provides a static price for Schedule II drugs, including cannabis. At this time, it is unclear if the price list will continue to be generated by CISC. The street value of cannabis has remained relatively stable over time (Boucher, Lawrence & Maslov, 2013). However, there are some variations that are not captured when using this price list to estimate the value of seizures. These include regional variations between urban and rural regions, and the North in particular. Moreover, price fluctuations occur when the supply-demand ratio is altered. In particular, price decreases occur when outdoor cannabis in Canada is ready for cultivation, and these variations are not taken into account when estimating the value of seized cannabis. Nor are prices differences between domestically-produced and imported cannabis products accounted for.

Upon completion of a cannabis seizure, the CBSA transfer the responsibility of the seized cannabis to the RCMP for destruction. The RCMP must submit an HC/SC 3515 form to HC for authorization before destroying the cannabis (see Appendix F).

Cannabis metrics are also analyzed and reported via Drug Analysis Report twice a year. These reports, produced by the CBSA, provide an analysis of trends in cannabis seizures, and inform the CBSA how to prioritize and better target investigations for cannabis seizures at Canada’s ports of entry. These reports are distributed to the CBSA, the Minister of PS, international partners, as well as federal partners such as PS. Ad-hoc products may also be produced, as needed and shared with relevant partners. Although not distributed publicly, these reports are available internally and may provide valuable information for researchers and policymakers when working with cannabis data. It is unclear if this information is shared with the CISC, which is responsible for establishing national price lists for illicit drugs.

Royal Canadian Mounted Police

Federal, provincial, municipal, and First Nations police services all have the authority to seize illicit cannabis. However, police-reported cannabis seizures are not centrally coordinated. While the RCMP is unique in that it provides federal police services, as well as contracted policing services in a number of provincial and municipal jurisdictions across Canada, it should be noted that findings pertaining to the procedure for collecting cannabis seizure data by the RCMP should not be generalized to all police services in Canada. It is beyond the scope of the current project to discuss what other law enforcement agencies in Canada are doing in regards to capturing and measuring cannabis seizure data.

The RCMP carries out a number of activities to fulfill its mandate, including those to combat organized crime and disrupt illicit drug markets. Through intelligence-led operations and roadside seizures, the RCMP investigates criminal offences relating to cannabis (RCMP 2015). The RCMP generally investigates cannabis-related offences in-land, while the CBSA operates along Canada’s borders. In 2015, the RCMP made 37,194 seizures of drugs listed in the CDSA of which cannabis represented 46% of the seizures. These 8,906 cases of cannabis seizures resulted in 1,771.7 kg of seized cannabis, which had an estimated value of $13.3 million.

The RCMP has a number of special initiatives that target illicit cannabis and use seizures as a performance metric. The Marihuana Footnote 4 Grow Initiative (MGI) targets illegal cannabis grow operations in Canada and also includes a centralized database that collects metrics on cannabis grow-ops that are dismantled each year. The MGI also includes geographical locations of dismantled grow-ops. The MGI database is currently not available to the public, but U.S. Department of State reports can be used as a source for the number of grow-ops and clandestine laboratories from previous years when the MGI database was operational and publicly available (U.S. Department of State 2014; 2015).

Project SABOT is a joint initiative between the RCMP and the Department of National Defense (DND) in an annual multi-jurisdictional marijuana eradication program of outdoor-grown cannabis (National Defence and the Canadian Armed Forces, 2016). This involves the use of aerial detection methods during the peak harvesting season of outdoor cannabis growing operations.

Since April 2015, the RCMP no longer uses the Significant Drug Seizure Report form to collect data, and instead enters the report directly into RMS to capture drug seizures. Data fields do not provide much in the way of specific details about the seized cannabis. In order to accurately quantify and qualify the seized cannabis, a tool the RCMP creates to supplement the variables collected into RMS directly are investigation "flowcharts" that detail each seized item. The RCMP requires the most amount of information possible on the seized cannabis when conducting their investigations. These "flowcharts" are used for the RCMP investigations and for court cases. However, they are only created in analogue format and attached to the case file, meaning that this data is not readily accessible or shared often because it is not machine-readable.

The RCMP identification of cannabis consists of the use of visual and scent testing to determine if the seizure is, or contains, cannabis. As with the CBSA, field tests may be used if needed but this is rare. Unknown samples or seizures where charges have been formally laid are typically sent to DAS for testing.

Once cannabis seizures are ready to be destroyed, the RCMP must submit an HC/SC 3515 to HC to authorize the destruction. The RCMP is responsible for carrying out the destruction process of seized cannabis products in their possession. Incineration is the preferred method for cannabis destruction, but any method that is allowed by the province in which they are located is authorized.

Previously, the RCMP had played a role in creating price lists for seized drugs, including cannabis. Since 2016, price lists are being generated by the CISC and are shared with law enforcement to be used to calculate the value of seized cannabis. At this time, it is unclear to what extent those price lists are used by RCMP in recording cannabis seizures.

Health Canada

All drug seizures may not always come to the attention of one centralized enforcement authority, such as the RCMP. Therefore, it is understood that no single enforcement authority has accurate data on the amount of cannabis seized across Canada. Authorization to destroy all seized illicit substances and record this information in a HC database is required under the CDSA. The CDSD is able to provide details on the quantity of seized cannabis (quantity indicated in the same manner as it was seized, in kg or L) that has been sent for destruction, as well as the number of plants seized. According to experts at HC, it is estimated that most seized illicit cannabis is sent for destruction and reported to HC. Therefore, the CDSD can be considered the most comprehensive database on cannabis seizures. The CDSD includes a reference number to the associated police file for the cannabis seizure. HC is not able to access RCMP or CBSA files directly to make modifications to the seizure data, even to confirm that a Certificate of Analysis was issued for an unknown seized substance.

Since HC is only responsible for the data entry of information provided through the HC/SC 3515, there are no measures in place to ensure that all cannabis is categorized uniformly. Information that is provided in the seizure report form is entered exactly as it is provided. Due to the fact that there can be a delay between when the cannabis has been seized and when an investigation has been completed, there are some discrepancies in the reporting timeframe for this metric. In the event that an investigation is completed in a different calendar year than the original seizure, it can be recorded in the CDSD for the following calendar year (RCMP, 2012).

HC also operates the Drug Analysis Service (DAS) to analyze and identify the presence of illegal drugs, including cannabis. However, only cases where formal charges are being laid or cases that are the result of an investigation or accident (such as a vehicle collision) are referred to the DAS. The DAS’ primary responsibility is the identification of controlled drugs and substances listed in the CDSA and in the Prescription Drug List and to produce a Certificate of Analysis. Currently, the DAS does not test for potency, purity, or strain of cannabis, either genetically, by cannabinoid profile, or morphological analysis, unless specific authorizations have been obtained. Due to high volumes of drug seizures in Canada, DAS analyses drug samples if the drug or case meets certain criteria (see Appendix K). Other responsibilities of the DAS may include: clandestine laboratory investigations support, providing training on testifying in court and, testifying in court as an expert (Health Canada, 2013b).

Data from the DAS is recorded in the LIMS (see Appendix D). The DAS receives only a sample of the seized cannabis, which is not representative of national seizure rates. Instead, the LIMS includes data on the chemical analysis of the cannabis seized. Other reports that the DAS is able to produce with the data include the number of exhibits that are submitted containing cannabis, as well as the number of requests for destruction.

The DAS provides additional guidance to police in the form of a DAS Client Manual (Health Canada, 2013b). This information pertains more to the procedure for submitting a sample as an exhibit, instead of providing assistance on how to complete the HC/SC 3515 form itself. In the past, some promotional material was developed by the DAS on how to complete the HC/SC 3515, although no further information was available about the status of these efforts at the time of this report.

Public Safety Canada

In 2007, the Government of Canada launched the National Anti-Drug Strategy (NADS). Led by the Department of Justice, 12 federal departments and agencies began to work together to "contribut[e] to safer and healthier communities by helping prevent use, treat dependency and reduce production and distribution of illicit drugs as well as by addressing prescription drug abuse" (Health Canada, 2014b). Three pillars are used to coordinate efforts most effectively across the various departmental mandates (Justice Canada, 2016a).

  • Prevention: Aimed at increasing youth awareness and understanding of the harmful effects of illicit substance use, and implementing community-based initiatives.
  • Treatment: Aimed at developing and implementing innovative and collaborative approaches to treatment and rehabilitation systems and services.
  • Enforcement: Aimed at disrupting illicit drug operations, targeting criminal organizations in particular.

A multi-targeted approach means that efforts do not just tackle the symptoms, but also address root causes. Enforcement of illicit drugs, such as cannabis, is an important element of the overall Anti-Drug framework. As the lead for the Enforcement pillar, Public Safety is responsible for national coordination of the action plan.

PS does not have a database for cannabis seizure data. Instead, PS is responsible for the policy work on cannabis law enforcement, based on existing legislation and drawing its analysis on existing data. Existing metrics enable PS to develop analysis on the use and context of cannabis in Canada for informed decision-making. Due to limited publicly available data, PS must work with PS partners to obtain information on an as-needed basis and through informal channels. This can present challenges in their role, because PS needs are policy-driven instead of operational. The types of information required may not necessarily be reflected in the data fields that are gathered by its partners. Moreover, there is a need to balance data methodologies from different sources, further complicating data analysis.

Media Reporting

Mass media is a powerful tool for bringing awareness to the public on a number of news items. With most media coverage tackling shocking events or dangerous trends, mass media coverage can highlight the profile of a particular issue or can conduct investigative work that exposes the dangers in the everyday. However, disproportionate media coverage on infrequent events may also lead to exaggerated fears of the public on the danger of a particular issue, commonly referred to as "moral panic" (Cohen 2002). Smaller seizures of cannabis occur regularly by law enforcement and often receive little or no media attention while significant (in quantity or value) seizures, or sensational seizures (such as those linked to sophisticated organized crime groups) are reported at a much higher frequency (RCMP Consultation, 2016). Fueled by fear of the danger of significant drug seizures, public pressure may direct the political agenda in a particular direction. Understanding the role and influence of mass media on public opinion is important, as it provides a pulse of public opinion in a particular space and time, and it also plays an important role in shaping public opinion, "often ‘breaking’ news and setting or framing the agenda of public debate" (MacNamara, 2005).

Illegal drugs have long been a component of mass media reporting globally. However, emphasis is typically placed on sensationalized events that are not representative of the drug problem and can cause the public to fear the worst possible outcomes. Media coverage is typically triggered by an event. While the event may be captured within data sources on the issue at hand, it can include outliers that are not representative of the dataset in general. Instead, "moral panic" may fuel public opinion that is not representative of everyday numbers for everyday people. Sensational mass media coverage can detract from more pressing issues or trends that may not be as dramatic, but which are more likely to have an impact on the general population.

While a comprehensive and systematic content analysis of media was not possible for this study, the literature search yielded several useful findings. Cannabis seizures are often sensationalized when reported. When reporting on cannabis seizures, the CBSA and RCMP provide raw numbers that do not include details on how representative the seizure is. It is the role of the media to locate and provide that information to the public. This type of reporting does occur, but is uncommon. While the RCMP investigates a number of cannabis seizure cases, it usually provides details to the media only for the most significant seizures or when the seizure presents public safety concerns. In the latter case, the RCMP may collaborate with HC on a bulletin which will receive greater media attention despite its infrequency (RCMP consultation, 2016). A meta-analysis of Australian media revealed that the figures of amount and value of cannabis seizures as presented in mass media were highly inflated. When compared to estimated values using cannabis data on plant yield and price from the research literature, reported values were as much as 11.9 times higher than research estimates times (Simons, Shanahan, and Ritter, 2011). While the authors acknowledge that there might be a number of potential reasons for the discrepancy between values as reported in the media and the estimates from the research literature examined in their study, it is important that greater transparency on the value of cannabis reported by the media, as well as the value used in data collection, to make better inferences about the impact of law enforcement in the illicit drug market.

Language also plays a role in fueling public fears of an issue by the media. Fear-based and speculative language shapes how a cannabis seizure is contextualized. Several RCMP articles include phrases that imply an increase in the danger of cannabis going undetected, "that otherwise might have been trafficked in our communities" (RCMP, February 25 2016; RCMP, 2015, September 30). No reference is made as to the significance of cannabis seizures within the context of the drug problem nationally, such as how typical this size of seizure would be. Other times, the street value of the seized cannabis is presented with large figures that are also presented out of context. Bringing the seizure closer to home increases the perceived impact of the seizure on individuals, their families, and their communities. High figures can be used to add "shock-value" to media coverage, with the effect of increasing public fear through exposure to atypical cannabis seizures. One news report compares typical cannabis with shatter, a highly potent form of cannabis with "THC level between 12 and 15 percent, [while] shatter is significantly higher … as high as 90 percent" (Wong, 2015; see also Davidson, 2016).

Media coverage of cannabis seizures generally take the figures provided by officials at face value, without seeking additional sources or verification (Larsen, 2016). The RCMP and CBSA provide figures on cannabis seizures to the media, but coverage is not necessarily representative of the illicit cannabis market in Canada. The CBSA indicated that seizure information that is released to the media is often produced as raw numbers with little contextualizing or breakdown of the seizures themselves. Value is automatically calculated by the RCMP and CBSA at the street value, resulting in large numbers that trigger public reactions. However, the wholesale value of seized cannabis is also an important measure of the current value of cannabis seized in large quantities, and can be up to 92% lower than the values shared in mass media "This is only about 8% of the RCMP’s claimed half-million value. But a press release about a $37,000 bust wouldn’t make headlines like a half-million dollar bust!" (Larsen, 2016). Other examples where cannabis seizure values were examined at the street value versus another value (wholesale, domestic/international) revealed similar findings (see CBC, 2014, November 14). A cannabis seizure in Taiwan that was destined for Australia revealed a price difference of $5.9M between the domestic and international value (Associated Press, 2016). Similar price differentials can also be found between separate domestic markets (Boucher et al., 2013).

Cannabis seizures at the border largely involve routine, personal seizures that are not reported on an individual basis. Larger seizures at the border that are sent to the RCMP for investigation occur rarely but garner significantly more media attention, contributing to public fears of the illicit cannabis market generally being dominated by sophisticated organized crime actors. Coupled with data on the number of cannabis seizures that take place at the border, which includes both the small personal seizures as well as fewer but larger cannabis seizures, the public may interpret media portrayal of cannabis seizures at the border as being both significant in the number of occurrences as well as the significance of each occurrence.

Presenting too much information can be just as problematic in creating moral panics as is presenting too little information. A recent coordinated raid of Toronto marijuana dispensaries in July 2016 illustrates this best when stating that 186 possession charges, and 71 profiting from the proceeds of crime charge were laid, resulting in ". 270 kilograms of dried marijuana, 30 kg of resin, 25 kg of hash, 27 kg of pills, 73 kg of chocolate, 142 kg of cookies, 129 kg of candies, 101 kg of bars, 135 e-cigarettes, 457 drinks, 127 kg of oils and spreads and 121 kg of other marijuana byproducts" (Global News, 2016). A police raid is by nature, not representative of the general number of cannabis seizures, which can raise public concerns about the pervasiveness of the problem, without contextualizing it in terms of other issues.

Training for Officials

The formal training received by law enforcement officers and forensic employees is an important consideration in determining best practices for data collection on cannabis seizures. Law enforcement officers are often the original source for data collection that provides the baseline metrics on cannabis seizures, before cannabis samples are sent for analysis or used as evidence in court. Front-line police officers are often responsible for conducting the investigation into a drug seizure (if any), conducting the seizure itself, and reporting the data using the relevant forms or databases. Any sworn officer with adequate training is able to conduct a drug investigation. However, larger-scale operations are usually handled by senior officers or speciality units. This study consulted two sources for training material relating to cannabis seizure training for law enforcement officers: the Canadian Police Knowledge Network (CPKN) and the Canadian Police College (CPC).

The CPKN provides online training for police and law enforcement personnel. Consulting the CPKN course catalogue revealed no specific training material pertaining specifically to cannabis, seizures of illicit drugs, or data collection. A 20-minute course titled "Report Writing" is available for law enforcement officers (CPKN, 2016; see Appendix G). This course informs participants of the importance of report writing in the police report pathway. However, given the basic nature of this training, the length of training, and the frequency that police are required to write reports, it is believed that the impact of on-the-job learning, report-writing culture, and demands on police services for resources will have a stronger impact on the quality of police reports than "Report Writing."

The CPC is a national police service of the RCMP that provides in-class training for law enforcement personnel across Canada, as well as internationally. The CPC develops advanced and specialized courses based on identified needs and emerging trends in policing. Two current courses were identified as being relevant to the training of law enforcement officers on seizures: Drug Investigative Techniques (DITC) and Clandestine Laboratory Investigations (CLIC) (see Appendix H; J). An Advanced Drug Investigative Techniques course was previously provided at the CPC (see Appendix I), but was removed from the curriculum, as much of the information is the same as the basic Drug Investigative Techniques training course.

The DITC training is in high demand, with approximately 170 police officers trained annually. Initially, police officers who were already in plainclothes speciality units were the only officers eligible to receive this training. However, due to police rotations, these police officers were often only able to apply the training in their final year of their placement. The DITC training currently targets young candidates who are interested in working in drug enforcement and is being expanded to include officers who work in smaller-sized police jurisdictions.

Training in DITC operates on the assumption that officers have never handled a drug investigation. The course outlines the investigation process from start to finish, and each stage is discussed in detail. DITC offers a separate module for cannabis, while marijuana grow-ops are addressed in another module in the CLIC training course. While the process for investigating cannabis is the same as with other drugs, the analysis is conducted differently. While field tests are used to test for most unknown drugs, cannabis has a very distinct scent and can often be visually- or scent-identified as cannabis. Field tests are costly, and cannabis can be easily identified by police officers, saving time and resources for additional police work. With the exception of identification of cannabis, the investigation of cannabis is treated like any other Schedule II drug.

The formal DITC training includes detailed measurement practices that consider how cannabis estimates vary based on a number of factors, such as if the cannabis is wet or dry, if the seized plants are mature or seedlings, or on which part of the plant that is seized. While there has been increased public concern in regards to cannabis seized in edible forms, there have not been enough cases yet to warrant additions in this area to the course at this time.

While police officers are not asked to estimate or report on the potency of seized cannabis, they do receive formal training that follows HC rules on how to handle illicit drugs. In particular, handling techniques are specified that will preserve the concentration of THC in seized cannabis. The course also provides training on procedures related to extraction techniques, measuring seized cannabis, and counting the number of plants during a grow-op seizure. While the CPC acknowledged that the potency of seized cannabis is valuable information, currently no training is provided in this area. It was acknowledged that there needs to be a balance in how these additional details are reported.

As part of their formal training in the seizure of illicit drugs, police officers are also trained to estimate the value of seized cannabis. Using examples of price lists that are generated through the use of informants, historical data, intelligence reports, as well as police networks, officers are able to estimate the value of seized cannabis. Unfortunately, these price lists are standardized across the country, and do not take into account regional variations or market segment (i.e., retail versus wholesale), sampling method consistency, price fluctuations due to supply and demand, or the need to update variables and price lists regularly. There have been initial discussions in considering teaching newer approaches to how seized cannabis should be valued that take into account more factors, rather than using values that are often inflated or calculated at the highest possible cost, though these have not yet been incorporated into the training received by police officers.

Canada Border Services Agency

During the hiring process for CBSA officers, all recruits go through an extensive training process that includes both an online and in-residence formal training components. Following 50 hours of online training, recruits attend an 18-week in-residence training at the CBSA College in Rigaud, Quebec. There, recruits receive structured training on the functions that they will need to perform as Border Services Officers, including how to perform inspections and conduct seizures. Once completed, recruits are appointed as CBSA officer trainees, where they will receive on-the-job training that puts their training into practice. The development program takes between 12 and 18 months to complete (CBSA, 2016b).

CBSA border officers also have access to intelligence products via the Customs Enforcement Library (CEL), and the Intelligence Tactical Operations Centre (ITOC) wiki page. These resources include information on conducting seizures, guidance to identify high-risk countries and import methods, as well as concealment methods. CEL is hosted within the ICES database, while the ITOC is available to all front-line officers. This enables officers to have access to the intelligence products remotely while conducting seizures.

Royal Canadian Mounted Police

Following successful completing of the RCMP recruitment process, Cadets must complete an extensive 26-week training program at Depot, the RCMP Training Academy in Regina, Saskatchewan. This training prepares RCMP officers for general duty assignments. RCMP officers with the appropriate competency profile may be considered for specialized units where they receive more specialized training on drug enforcement and investigations. In 2012, the RCMP launched an online training initiative on its MGI database to report illegal cannabis grow operations in Canada. As of 2015, over 1,000 officers have taken this training (U.S. Department of State, 2015). Other training initiatives include the Pipeline/Convoy/Jetway initiatives that provide training on detecting and apprehending traveling criminals on local highways. The Jetway component of this initiative focuses on stopping the transport of contraband through the use of local bus terminals, airports and train stations by organized crime groups (RCMP, 2009).

Health Canada

DAS has developed training modules that provide training for police officers in handling and preparing drugs that require processing to be submitted to the DAS lab for analysis as exhibits for court. This training is available in both official languages, and is given at an appropriate facility provided by the police service requesting the training. Available modules include: 1) dismantling a clandestine laboratory; 2) drug analysis and identification; and 3) evidence and exhibit sampling. The cost of travel and salary of DAS employees to deliver this training is covered by HC, and is offered at the discretion of the DAS unit (Health Canada 2013b).


Interpretive Cautions

Current cannabis seizure data must be interpreted with caution, especially when using data from different sources. Experts have highlighted the need to interpret all cannabis seizure data with restraint because of the importance of context in the case of each seizure. Raw data on cannabis seizures mean little without robust analysis of the context of cannabis seizures and how it fits into the context of the drug market in Canada. Researchers have identified a number of factors that bear consideration when interpreting cannabis seizure metrics as they stand today.


One of the primary cannabis metrics that is used in understanding the drug situation in Canada is that of the value of seized cannabis. While value provides a tool for measuring and comparing seizures, it can also be quite problematic.

As several consulted experts have indicated, the reported value of seized cannabis is generally inaccurate, unless the cannabis was seized as part of an undercover operation. Similar to purchasing a used car, the price of cannabis is only valid at the point of the exchange and average general market prices may not necessarily be representative of any given seizure. The price will vary with the demand, quantity, quality, region, the relationship between the buyer and seller, and other variables. Bulk seizures are conventionally valued at street level (i.e., commercial, illicit retail) prices, and cannot capture the wholesale prices at which the cannabis is valued at a particular point in the supply chain (Caulkins, 1994). Values assigned by roadside officers cannot be accurate, as it is nearly impossible to estimate all the contextual factors that make up the value of that seizure. In the event that a cannabis seizure goes to court, a detailed price analysis can be conducted by an expert. However, no expert advice on price is given for seizures that do not result in a court case.

There have been efforts to change the process for valuation, but even estimates that are developed through intelligence by informants, regional price fluctuations, and supply-demand cycles are changing constantly. Currently, price lists for seizures of illicit drugs provide some indication for seizures in different measures, such as dosage, gram, and kilogram and are coordinated through the CISC on an annual basis. However, these prices are set at the national level and are not adjusted for other important factors that influence the value of the seizure. Creating more detailed price lists that are used to estimate price might be beneficial at reaching more accurate valuations for cannabis seizures, but these will continue to be best estimates.

Differential Enforcement

The number of police resources dedicated to the enforcement efforts against drugs, including cannabis, has a significant impact on the reported levels of cannabis seized. Policing priorities shift over time, targeting certain crimes, regions, being reactive or proactive towards certain enforcement areas. These priorities directly impact the level of resources that are directed towards certain activities, such as drug law enforcement. The World Drug Report has identified the important role the level of resources dedicated towards drug seizures has a positive relationship with the number of drug seizures that are reported (UNODC, 2016).

Proactive cannabis seizure efforts can target larger-scale operations or direct additional police resources towards increasing the number of small-scale cannabis seizures, while a reactive approach encourages random searches, decreasing the likelihood of significant cannabis seizures. In part due to limited authority and resources, targeted investigations to seize illegal drugs being exported from Canada has not been set as an organizational priority (Office of the Auditor General, 2015). There is a need to acknowledge that the operational capacity of enforcement organizations, as well as organizational priorities for law enforcement activities, contributes to the number of reported cannabis seizures (Leone et al., 2012). Broadly speaking, historically in Canada, trends in drug crime offences and other crime tend to move in roughly opposite directions (Cotter et al., 2015).

The majority of the seizures at the CBSA result from smaller-scale import seizures (95% of cannabis seizures are under 200g). Large-scale individual seizures by the CBSA, which account for only 5% of seizures, are the result of both random identification and intelligence-led operations. The RCMP is responsible in investigating larger-scale cannabis smuggling operations led by organized crime groups, though the CBSA is generally involved in all cannabis investigations through joint force operations with the RCMP. During consultations, one expert noted that although canine teams can increase the number of cannabis seizures, resourcing constraints mean that this method of investigation is not generally used consistently at each port of entry, impacting the rate of "positive" searches that result in a cannabis seizure (CBSA Consultation, 2016).

The Canadian cannabis market is increasingly made up of a combination of both licit and illicit cannabis, all with the potential for seizure. More and more, cannabis may become the object of a criminal offence and seized for reasons that are not associated with its illicit nature. Distinction will need to be made between illicit cannabis seizures and licit cannabis seizures. Illicit cannabis seizures would usually be defined by the fact that the seized material could be considered contraband, while licit cannabis seizures might be defined as seized legal material that is in law enforcement’s possession as evidence or assets associated with criminal behaviour not related to a drug offence (such as theft, fraud, proceeds of crime, taxation or contractual disputes, etc.). This distinction will need to be taken into account when developing trends in cannabis seizure rates.

Operational data tracked by police services and enforcement agencies includes some information on the level of resources dedicated to enforcement activities. Changes in trends of seizure data within one organization or in a particular jurisdiction would do well to incorporate the level of resources dedicated to cannabis seizures. This would enable more accurate inferences of the drug market context at any given time. More specifically, resource data could be used in cannabis seizure analysis to develop more reflective assessments of cannabis-related patterns.


None of the consulted experts considered it operationally feasible to measure the potency of cannabis seizures. From an operational perspective, this information does not provide enough value for the amount of resources required to conduct potency analysis of cannabis seizures as a standard practice. Not only is potency data valuable for policy makers, it is also reflective of trends that are useful for intelligence purposes. Methods of obtaining this information in a way that is feasible will require further reflection.

Data Accessibility

Consultations revealed that data accessibility was one the biggest challenges in the collection of data and analysis of seizure metric data. More consistent reporting between agencies and with the public is needed. A wealth of information is available and recorded by partners working to achieve the objectives of the National Anti-Drug Strategy. However, the accessibility of this data between departments and agencies continues to hinder a comprehensive analysis of the issue. A number of specific areas for potential opportunities were identified.

Data Linkages

Several opportunities for greater co-ordination of information were identified through the consultations for this research. Data sharing is currently triggered by a need from one organization and is made possible through informal channels such as networks and personal contacts. Data must be extracted from requested databases manually and shared with partners, with personal identifying information removed for confidentiality. Information that is not stored electronically, such as analogue "flowcharts" used by the RCMP, are often not included in the data exchange. Due to the resources that would be required to collect and transfer analogue information, it is usually not feasible to include information that is not electronically stored and accessible. Formalized communication and data sharing methods have the potential to increase the frequency of data sharing outside of specific ad-hoc requests. Furthermore, formalized communication channels are important for ensuring that data sharing is not limited to certain areas within organizations but available more broadly.

Formal agreements between organizations on data-sharing and the ability to link records enable robust data sets to be built and analyzed. Data linkages have the ability to improve the operational effectiveness of individual agencies, and undertake policy and trend analyses that would be impossible with any single database. For example, potency data from HC’s LIMS database could be combined with RCMP or CBSA seizure data and be included in CISC’s price data to reveal improved price modelling for more appropriate valuation determinations. This would complement more detailed data for research and policy work in the area of cannabis seizures across organizations.

System Interoperability

Each department or agency that is responsible for recording cannabis seizure metric data operates a separate database. Data is captured in proprietary databases according to the objectives of the organization with respect to the data, and particular structures and fields have evolved over time as they work towards fulfilling their mandates. For example, while all fields within the ICES database respond to the operational needs of the CBSA, only certain fields may be useful for partner organizations, such as HC. As data is shared between partner organizations, such as the CBSA and HC, discrepancies in fields used by each database may result in loss of information or data gaps. While the CDSD may contain the most comprehensive data on cannabis seizures, this data is less detailed than the records held by the CBSA. Such discrepancies in database systems may result in data gaps or loss of information in instances of data sharing, hindering their effective use.

As defined by its jurisdictional boundaries, the CBSA’s ICES database is designed to act as a repository for data that is collected at Canada’s ports of entry. The ICES database is useful for gathering intelligence on cannabis seizures along Canada’s borders. The RCMP’s RMS database can be used for national intelligence on cannabis seizures that take place inland, or along Canada’s borders that are not located at a port of entry. RMS feeds data to the Uniform Crime Reporting Survey (UCR) on a monthly basis via an interface designed in accordance with UCR rules. RMS includes data on investigations of cannabis seizures that are relevant to police services and large cannabis seizures along Canada’s borders (typically related to organized crime). Since these systems are not intended to collect the same information, data must be transferred in an alternative format so that it can be used by the receiving organization. In the transfer, data may be excluded or lost. Similarly, neither the ICES nor RMS systems are compatible with HC’s CDSD. Data for comprehensive metrics on the total cannabis that has been destroyed is entered manually by HC employees by submitting paper copies of the HC/SC 3515. Some data can be automatically generated by the RMS system into an electronic version of the HC/SC 3515. However, this form is still currently submitted in paper format to HC. System inoperability also increases the potential for error as information is translated from system to system, as well as delays in reporting information in a timely manner. Regardless of any reluctance between organizations to share data, this exchange is further challenged by the lack of system interoperability between existing databases.


Cannabis intelligence and expertise on illicit drugs exist across the PS portfolio, within police agencies and at HC. Products such as the RCMP’s National Intelligence Reports, RCMP seizure data and trends, CBSA intelligence products, and HC’s inventory of all controlled drugs and substances all contain valuable data that is useful for informed policymaking efforts as part of the National Anti-Drug Strategy. All drug seizures at Canada’s ports of entry, including those over three kilograms or one litre, are captured within CBSA’s databases and intelligence products. However, RCMP National Intelligence Reports only includes data on large cannabis seizures over three kilograms or one litre. While it is possible to cross-reference the RCMP statistics with CBSA statistics to prevent double-counting, it is often only the final reports and not the raw data itself that is being shared for analysis, preventing such analysis from occurring.

There appears to be a disconnect between the data needs of operations and policy across partner organizations. Operational consultations highlighted the need to quantify cannabis seizures in a way that does not overburden the reporting process, which maximizes the ability to triage more serious cases for intelligence purposes, thereby maintaining the integrity of evidence. These considerations result in establishing purposive thresholds for dealing with solid versus liquid substances and practices regarding the inclusion or exclusion of packaging that privileges later operational uses for the sample and collected data.

A horizontal approach to drug enforcement in Canada removes roadblocks imposed by data that is segmented by jurisdictions and mandates. Policymaking that reflects the drug situation across Canada requires that a number of datasets are pieced together before fulsome analysis can occur. In sharing certain information to the RCMP, confidentiality considerations restrict some data from being included. There may be a concern that identifying information that was collected for certain purposes will be used by the RCMP to conduct an investigation. There are several hub models that could be used to meet the need to build a complete picture of the state of cannabis in Canada. During consultations, several experts referred to centralized models, such as the United States’ Drug Enforcement Agency model that serves as a centralized information point for all data pertaining to controlled drugs and substances. Moreover, this has the potential to streamline reporting and ensure greater data accuracy which, despite its complexity, is very important. Furthermore, a formalized horizontal or national strategy that synchronizes the data needs for both operational and policy considerations across jurisdictions would contribute to more informed decision-making.


Generally, experts revealed that access to necessary information across organizational jurisdictions is limited. It is possible that data can be shared with different organizations in a number of scenarios: shared unilaterally in a one-way exchange between organizations, reciprocally, or not shared at all. While organizations reported that they were open to sharing information themselves, most organizations indicated that the data received from other organizations was challenging (CBSA Consultation, 2016; RCMP Consultation, 2016; PS Consultation, 2016; HC Consultation, 2016). Lack of formal mechanisms, such as reporting requirements, was cited as a contributing factor to roadblocks in information-sharing.

One area that was identified as particularly problematic is competing legislations that undermine the authority of enforcement agencies to conduct seizures. Both the Customs Act and the Canada Post Corporation Act place limitations on enforcement authorities to examine suspected mail that is under 30 grams without the consent of the sender or addressee. This creates a legal vacuum, since Canada Post does not view its role as a law enforcement body, but to merely comply with its requirements under the Canada Post Corporation Act. This highlights the need for greater cooperation between enforcement authorities responsible for seizing cannabis and auxiliary organizations, and/or legislative reform.

Data Reconciliation

Data reconciliation is the process by which initial data is verified and updated to reflect new information. Cannabis seizure metrics may be transferred between several organizations from the initial cannabis seizure and reporting to the final destruction, depending on the case.

For example, a large cannabis seizure by the CBSA will be initially entered into the ICES database before the responsibility for investigating the case is transferred to the RCMP for investigation, using the RMS database. In anticipation of an investigation going to court, a sample of seized cannabis is sent to DAS as an exhibit for court, where the results of the analysis are recorded in the LIMS database. DAS will also issue a Certificate of Analysis to be included in the court files, along with the final court ruling. Following the completion of a completed seizure, investigation or case, authorization from HC must be obtained prior to destruction. Requests for destruction are captured within the CDSD by HC. Data is generated along several points by different partners and recorded at different stages of the investigation. Overburdened caseloads may prevent information that is generated by other partners to be reconciled with in the original data. This may result in a failure to provide a complete picture of each cannabis seizure. Figure 1 illustrates how the data is captured at different points of the cannabis seizure. Without data reconciliation, the snapshot provided by each database remains incomplete.

Figure 1: Example of data captured in regards to a cannabis seizure Image description

The figure demonstrates the capture of cannabis seizure data for the three enforcement authorities who manage databases holding cannabis seizure data. The type of information captured within each database is reflective of operational. The data generated from a single cannabis seizure is captured within multiple databases. Thus, some information may be lost during the transfer of responsibility of data between enforcement authorities. Not all types of information are available for each cannabis seizure, depending on the circumstances.

Best Practices

Lack of standardization across databases or within organizations can lead to inappropriate conclusions being drawn from cannabis data. Taking steps to ensure greater consistency would increase the reliability of data and of the analysis. There are currently no mechanisms or direction to ensure that reporting methodologies between departments are consistent. While cannabis seizures are carried out fairly consistently across organizations, the reporting process varies within and between organizations. As a result, cannabis seizure data cannot be used to gather an accurate representation of the drug situation in Canada. Lack of standardized measurement was found in a number of areas within the data collection process. Cannabis is a drug that is found in varied forms, increasing the difficulty in developing guidelines on how to treat cannabis systematically.

POLIS is a CACP committee that "supports progressive change in policing, in partnership with the Policing Services Program of the Canadian Centre for Justice Statistics (CCJS), a Division of Statistics Canada, and other partners, through the development and communication of meaningful public safety information." (CACP 2014b). POLIS collaborates on initiatives to improve the data collected by police that can be used to improve policing. This may be an appropriate forum where a standard cannabis seizure reporting instrument, with CACP board approval, be recommended to be implemented across police services in Canada should one be developed. The Ontario Provincial Police (OPP) has also developed an inventory of organized crime committees in Canada at the federal, national and provincial levels that could be used to identify relevant networks (Baks, 2014). Another appropriate venue for disseminating the consistent approach for reporting cannabis seizures is the National Coordinating Committee on Organized Crime (NCCOC), whose mandate is to function as a body of federal/provincial/territorial (FPT) representatives from the law enforcement community to identify major trends and determine national policy priorities related to the issue of organized crime. FTP research fora and FPT health fora would need to be engaged if coordinated approaches are to be successful.

Record cannabis seizures, at least roughly, by type and quality
Specialized units for cannabis enforcement often have the knowledge necessary to identify the quality of cannabis seized and the cannabis strain, using visual and scent identification methods of common drug characteristics. However, frontline officers without specialized drug training reported that once they are required to consider cannabis grades—such as hemp or "ditchweed" versus seeded psychoactive cannabis with adhering leaves to flowers versus unseeded, trimmed psychoactive cannabis—they do not feel qualified to make an assessment, whereas such an officer could likely make an estimated classification of distinguishing between beer, wine, coolers or distilled liquor. As a result, cannabis seizure may be over-valued. Taking steps to ensure that cannabis reporting reflects cannabis strains would result in more reliable cannabis data that is intended for distribution within the drug market in Canada, and enable policymakers to more accurately target areas of concern. Without investing resources into specialized drug training, it may be possible for frontline officers to, at least roughly, identify the type and quality of cannabis seized. This could lead to more accurate metrics that would be useful when conducting research or policy work using seizure data.

Develop national empirical standards for calculating cannabis plant yield
When cannabis is seized as a plant, every plant is counted and reported. While this number reveals highly accurate data on the actual number of plants seized, measuring and valuing these seizures are challenging. Standard practice is to estimate $1,000 per plant; however, plant yield can vary greatly depending on a number of factors. Plant maturity can vary significantly between cannabis plants seized in the same seizure. Cannabis plant seedlings may yield an ounce of cannabis or less when mature or they could grow to become "Christmas tree"-sized plants producing pounds of cannabis. A seizure of cannabis in a grow-op where the cannabis was all grown for the same amount of time may vary according to the specific degree of lighting or moisture they received, or the strain of plant. Currently, plant seizures are counted in a generic and indiscriminate manner, without considering factors that impact plant yield and value. Developing national empirical standards for reporting cannabis plant seizures based on such factors would greatly improve the value of this metric, contextualizing the number of plants seized by their yield and impact in the cannabis market overall.

HC provides plant yield estimates in the ACMPR: 30 grams for indoor-grown cannabis and 250 grams for outdoor-grown cannabis (Department of Justice, 2016a). It should be noted that the methodology for these calculations is unclear, and should not be used when interpreting current cannabis seizures by enforcement authorities. Health and law enforcement standards may need to be different; the standards used for medical purposes may not be appropriate for enforcement authorities, and further study should be pursued.

Develop national enforcement standards for measuring seized cannabis products that do not include packaging or other seized materials
Despite recognition by partners that not all seized cannabis products should be treated equally, the weight of seized cannabis products is the primary method that is used to measure seized cannabis. Cannabis in wet form includes additional weight from the moisture in the drug, while dry cannabis does not. Cannabis is increasingly seized in the form of edible products. Often, the amount of cannabis is not readily identifiable unless the purchase includes official manufacturing packaging with details on the amount of cannabis included. Some details on a more accurate amount of cannabis in seized edible products may be gathered by questioning the individual, but this reported amount may be subject to falsification or subjectivity biases. Additional weight from other material is also included in the recorded weight of a cannabis seizure. The quantification of seized cannabis needs to be stabilized to account for differences across seizure occurrences and to have reliable data for analysis, such as the weight of wet, dry, or cannabis-infused products that can allow for accurate comparisons. Efforts to assess the quality of the seized cannabis may be made; however, a lack of enforcement standards may result in subjective assessments of "high" or "low" quality cannabis by enforcement authorities without specialized drug training. Any attempts to currently provide additional information are not done consistently. Additional information is recorded within the notes of the record, and not in the primary data fields that are usually pulled for analysis.

Using seizure data with other metrics to estimate market size
Having accurate data with which to construct production estimates is required to apply seizure data to the question of market size. Prior to 2010, seizure data was routinely used to estimate the volume and value of cannabis drug markets. Despite recognition that not all available cannabis in the market is seized by enforcement authorities, seizure data is still valuable in estimating the market size. While this data has certain limitations, it would, if properly measured, provide better estimates of the amount of cannabis that is supplied to the consumer market. As it stands, seizure data should still be interpreted with caution, or in conjunction with other metrics when possible.

Primarily, market size from cannabis seizures can be estimated using the value ($) of cannabis within a given market. As discussed earlier, unless a seizure is valued by an expert, the data being collected in regards to cannabis value does not provide analysts with comparable data across seizures or enforcement authorities. Market size of cannabis is also inferred from the amount (in kg, L, or #) of cannabis seized. Again, this data should be supplemented by other metrics when calculating market size.

Changes to the level of resources being committed to seizure activities or in certain areas will influence the amount of reported cannabis seized, as cannabis seizures and level of resources are positively correlated (UNODC, 2016). The amount (again, in kg, L, or #) of cannabis seizures is not necessarily useful on its own to indicate market size. Having regions of Canada that share borders with jurisdictions with U.S. states that have cannabis regimes that differ from our own has already led to increases in the number of cannabis seizures (CBSA Consultation, 2016). The imports of cannabis from legal to illegal markets are recorded as cannabis seizures, regardless of the intention of the individual. These seizures undoubtedly influence the data being used to estimate the size of the cannabis market in Canada, despite their unknown effect on market size at this time. The number of cannabis seizures is expected to increase significantly at Canadian ports of entry as more neighbouring jurisdictions adopt medical, regulated or legalized cannabis regimes.

Databases take into consideration both operational and policy needs
All experts consulted during this process referred to challenges in accessing seizure data necessary for their work. Data sharing is a cumbersome, time-consuming process which is generally informal and inconsistent. Potentially rich data sources, such as RCMP flowcharts, were identified but continue to exist in analogue form only. In instances where data is requested from another organization for intelligence or policy making, it is common for only digital information to be included. Thus, while some information is made available, there is a loss of data that is heightened by data recording practices, which presents a bias in the data available for research and policy.

The operational focus for the data collection of cannabis seizure metrics by organizations serves several functions: using a threshold of volume enables the triaging of more serious cases and subject matter experts; measurement practices are developed to minimize problems in maintaining the integrity of the chain of evidence; and operational capacity is maximized through expending resources on determining the most relevant intelligence information—the presence or absence of substances (and not the concentration or form of the substance). Numerous experts identified that research or policy questions would benefit from additional information that operational colleagues do not consider necessary to record. The data needs for policy work is not always congruent with the operations of the organization collecting the data. For analysts, this can lead to data gaps that leave certain questions unanswered or imprecise. Considering policy needs, while respecting the burden of data collection on the operations of the organization, should be considered in determining which data fields are most relevant in each database.

Structured databases to allow for data linkage
Due to the nature of cannabis enforcement in Canada, cannabis seizure data is collected by several partner organizations in separate databases across the government (see Figure 1). Operational and policy needs of each organization vary by their mandate, and the relevant seizure data needs are translated into each partner’s databases. While there is a desire to access data from their partners, sophisticated operational and policy analysis requires that seizure databases be structured with a selection of identically formatted and frequently populated variables that would allow for data linkages. The ability to link datasets for thorough analysis may not address the limited ability for partners to access each other’s data in the first place.

Formalize partnerships for regular data sharing that is not triggered by "need"
Often, analysis by each organization in respect to their mandate would benefit by a more complete picture of the cannabis market as a whole. Additional data is currently requested through informal mechanisms, and may result in differential access to information across or within partner organizations. Need-based requests may only be incorporated to fulfill the original data requirements and may not be accessible for additional analyses. Formal mechanisms that would allow for systematic data sharing on a regular and co-ordinated basis that would enable this information to be taken into account during routine analysis of the cannabis market.

Seizure reporting that tracks if a seized drug was licitly or illicitly produced or sourced at point of origin
Estimates of the cannabis market are complicated by a number of cannabis seizures that are inadvertent in nature, particularly as the number of bordering jurisdictions develop independent cannabis regimes. A legality of cannabis within the medical regime is complicated when possession, production of personal amounts of cannabis, and the distribution of cannabis between individuals or legal produces intersect with the illicit market. In addition to inadvertent seizures, better trends of the cannabis market can be developed if data is available on the point of origin of the seized cannabis. Distinguishing seizures that are intended for import and export may reveal relevant data for both policy and operational purposes.

In addition, a situation is emerging where multiple markets are emerging side-by-side for both illegal and legal cannabis. From the point of view of enforcement and policy, it is useful to know if seized cannabis originated: 1) in a licit manner then was diverted to an illegal market (making it "illicit cannabis"); 2) in an illegal market and was diverted into a legal market (making it "counterfeit cannabis"); or 3) in the illegal market and remained in the illegal market (making it "contraband cannabis"). The operational and policy issues emerging are similar to that now faced with regard to illicit tobacco.

Track seizures of non-standard cannabis products in as much detail as possible
In considering the most appropriate way to collect data that reflects reality, it is important that reporting provides adequate structure and flexibility to meet the needs of all parties. Cannabis is being seen in a number of new forms of cannabis-infused products (e.g. creams, oils, butters). While direction is needed when confronting emerging forms of cannabis consumption, it may be appropriate to consider to what degree flexibility should be incorporated within the existing fixed data categories. Currently, cannabis-infused products fall in a grey area that may be subject to interpretation. At the same time, providing structure through mechanisms such as fixed data templates with pre-determined options ensure that data is categorized within the established parameters and prevents data from becoming lost in "other" categories. As emerging forms of cannabis are increasingly exchanged in the drug market, there will be a need for further guidance to ensure that emerging threats are measured systematically across and within organizations.

Application to Other Metrics

The discussion in this report has thus far focused on how the metric of cannabis seizures is currently being measured, recorded and reported by law enforcement authorities in Canada. Some suggestions for improving the way the metric is currently being measured were offered. The next section of the paper addresses the issue of how the metric of cannabis seizures can contribute to an array of other metrics, if some of the improvements are introduced. The metrics presented below were discussed, to an extent, in Maslov et al. (2016). The discussion highlights the importance of collecting accurate information on cannabis seizures, as cannabis seizures play a crucial role as a root metric for other metrics.

Illegal Production and Cultivation

Cannabis is a plant that must be grown, cultivated and harvested, either indoors or outdoors. The plant itself does not require much attention and can grow as a weed in many climatic and soil conditions. However, some knowledge and experience in running a grow-op is required when production is aimed at cultivating large quantities of higher potency psychoactive cannabis. Thus, the metric of illegal production and cultivation measures the number of cannabis plants cultivated and the amount (kg, L, or #) of cannabis products. Since the growth and production of cannabis is still an illegal and criminal activity in Canada, no producers will voluntarily submit the production numbers that are required to calculate this metric. There is no public database that would contain information on illegal production and cultivation. The only way this metric can be directly measured is through the recording and reporting of seizure information by law enforcement. This data originates from law enforcement reports on grow-op seizures, investigations, anecdotal material and some projections made by criminologists and economists using statistical modelling methods. The projections and estimates are examples of indirect measurements of illegal production and cultivation, which would include several assumptions that could drastically affect the estimates.

Bouchard (2008) estimated a mean rate of 1.9 ounces of marketable cannabis per plant, with a 0.4 standard deviation in a self-reported study of cannabis growers in the province of Quebec. This is consistent with productivity rates found in other studies (Hough et al., 2003; Toonen, Ribot, and Thissen, 2006; Wilkins et al., 2002) although few have actually measured productivity rates for outdoor plants in industrialized countries.

In 2013, cannabis production in Canada accounted for 96% of all illicit drug production reported by police (Cotter et al., 2015). About two-thirds (64%) occurred in a private home or surrounding structure (such as a garage or shed), while more than one-quarter (27%) occurred in an open area (areas of public access, parks, playgrounds, bodies of water, etc.) It is important to remember that this metric is only informed by cannabis data that is brought to the attention of police.

Other, somewhat older findings indicated that the number of marijuana grow operation cases that came to the attention of law enforcement in BC tripled from 1,489 in 1997 to 4,514 in 2003 (Garis, 2009). While statistics such as these do suggest a dramatic increase in the number of grow-ops, they are largely based on the number of tips that come to the attention of the police; they do not represent the actual number of founded cases (Plecas et al., 2005: 21). The number of cases that were founded was actually 1,250 in 1997 and 2,031 in 2003 (ibid: 21-22). Furthermore, increases in the number of tips that the police receives may depend on factors other than the sheer number of grow-ops. These could include public awareness campaigns and the amount of media attention given to the issue (Carter, 2009).

Significant production and illicit commercial cultivation of cannabis has been identified primarily in BC, Ontario and Quebec (U.S. Department of State, 2014). The illicit commercial cultivation of cannabis in Canada produces mostly high-potency, indoor-grown marijuana for both domestic consumption and export to the United States. Because the majority of cannabis produced in Canada are grown indoors (in grow-ops), aerial images filming the outdoors grow-ops tend to miss about 75% of cannabis cultivation sites (Kalcska and Bouchard, 2011).

The illicit nature of the production and cultivation of cannabis means that these numbers are mostly estimates and, on their own, are limited in their usefulness. In order to make the illicit production and cultivation data more practical, it needs to be combined with other information, such as a measurement of the level of resourcing for enforcement, the approaches taken by enforcement, the number of founded cases and the prompt recording, reporting and linking of the seizure data by all levels of enforcement. By properly combining this metric with others, researchers can better analyze the overall cannabis market, what segment of the market is destined for domestic consumption or exportation, the extent of the involvement of organized crime in the cannabis market, how the crime operates within the market and the nature of the associated harms, and the contribution of the cannabis industry to Canada’s licit and illicit economy.

Results from the CCJS consultation with selected police services indicate that most of the police services that were interviewed collect information on illegal production and cultivation. The information collected is for investigative work. It is impossible to know what information is actually collected due to its confidential nature. No data on the illegal production and cultivation of cannabis can be shared until the investigations are complete, and even then the process of sharing this information is far from straightforward.


Marijuana and cannabis products may contain psychoactive substances the consumption of which may produce the effect of "high" or psychotropic effects. The metric of potency measures the percentage of concentration of these substances, most commonly tetrahydrocannabinol (THC), but sometimes cannabidiol (CBD), in the cannabis product. The metric of cannabis potency appears frequently in public discussions on the harms and benefits of cannabis, driving under the influence of cannabis, or the police’s impact on illicit cannabis-related activities.

The necessary data for this metric can be obtained by properly recording and reporting information on illicit cannabis seizures that are sent for analysis in HC’s DAS. It may also come from independent lab analyses, or analyses conducted by health care practitioners or researchers. Regardless of the source of data, it is extremely difficult to obtain information on the potency of cannabis samples, especially if the data distribution needs to be representative of a jurisdiction, province or Canada. Not all of the seized cannabis is sent for analysis to DAS; only cannabis that is part of an investigation is examined in the lab environment to support the evidence required for the court. This data on potency is not shared publicly due to its confidential nature. Potency data that is collected by health care practitioners or researchers is usually part of a one-off study that answers a certain research question. It is not meant to—and cannot—support the calculation of general metrics of cannabis potency in Canada.

From the little information on cannabis potency that is available to researchers and policy makers, it may be said that the potency of illicit cannabis has been increasing since 1975 in the U.S. and Canada. The average percentage of THC increased from about 1% in 1975 to over 12% in 2013 in the U.S. (United States, 2014; Slade et al., 2012). Similarly, the average percentage of THC available in samples increased from about 1% prior to the early 1980s to 10.3% by 2006 in Canada (Slade et al., 2012).

Measuring the potency of cannabis is important for many reasons. First, the number of emergency room visits and hospitalizations in Colorado has increased since the legalized cannabis regime was introduced (Rocky Mountain, 2016). Although there have not been any formal studies of the issue, anecdotal evidence suggests that the increase could be attributed to an improper consumption of higher potency cannabis products such as edibles, especially among children (Mohney, 2016). Second, the potency of consumed cannabis will impact the user’s psychomotor performance, which becomes especially important during activities like driving (Tchir, 2015). Third, the link between the price of cannabis and the potency has yet to be studied in the legal and illegal contexts, although there is some indication that the relationship could be negligible (Ben Lakhdar et al., 2016). Finally, the potency of cannabis may affect an array of other cannabis-related metrics such as mental health, cardiovascular diseases and cancer, respiratory effects, length of impairment, overdoses, etc. (for more discussion, see Maslov et al., 2016).

Canada does not currently have a standardized method for measuring the potency of cannabis in the fields of policing (seized illicit cannabis) or medical communities (licit medical marijuana). Appropriate seizure metrics and potency metrics are strongly interrelated. Without the potency metric, the seizures measured as number of plants could be quite meaningless because the seized plants could be of low potency. Furthermore, it is not appropriate to compare seizures to one another in either the amount of seized cannabis product or the number of plants, because the seized cannabis is likely of a varying potency. While it is unrealistic to expect a potency analysis from every seizure performed by law enforcement, it is conceivable to submit a sample of the seized cannabis to begin the proper collection of information for the potency metric. It would also be beneficial to begin releasing the information and analyzing the potency of cannabis that is already tested by DAS. This analysis could begin the process to supply the much needed data for the cannabis potency metric.

Results from the CCJS consultation with selected police services indicate that none of the police services interviewed collect information on the potency of cannabis. The majority indicated that it would be DAS that performs the potency analysis, which is very time-consuming and costly. The majority also indicated that it is not practical for law enforcement to collect such information.

Eradication of Illicit Cannabis

Whenever illicit cannabis or other drugs are seized by law enforcement, they need to be destroyed (eradicated) at the end of the judicial procedure. Sometimes they are kept at a secured facility as evidence or while the investigation is ongoing. If the amount of seized drugs is especially large or the facility does not allow for safeguarding the drugs, law enforcement would apply for authorization from HC to perform an emergency eradication.

In Canada, data that informs the metric of cannabis crop eradication is absent. In theory, law enforcement carries out the eradication, and HC, which issues the permission to eradicate seized drugs, should be the main sources of the data. However, this information is strictly confidential because of its association with investigative work, and it cannot be shared publicly. The information could be released to the public or the media under the Access to Information Privacy Act, but these releases tend to be single stories or articles and should not be viewed as a nationally representative portrait of the situation on crop eradication. When the information becomes available to the public or the media, it is usually reported in the form of number of plants seized and destroyed (or raw weight of cannabis destroyed) by law enforcement.

By default, the metric of crop eradication only measures the eradication of cannabis that is: 1) based on information that came to the attention of law enforcement; 2) largely based on reactive approach to policing; and 3) only accounts for the seized cannabis products that were destroyed by law enforcement. It does not—and cannot—account for cannabis crops and products that were eradicated by jurisdictions other than law enforcement (i.e., the producers, users or anyone else other than law enforcement).

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Perhaps not surprisingly, the eradication efforts of outdoor grow-ops have led to an increase in indoor grow-ops (Diplock, 2013). This follows the criminological theory of crime displacement as a result of crime prevention activities by law enforcement (see Bowers et al., 2011; Guerette and Bowers, 2009). The detection and policing of outdoor grow-ops is becoming somewhat easier with the development of surveillance technology than the indoor grow-ops. Marijuana plants grown outdoors for the purpose of drug production are more similar to "ditchweed" and hemp than cannabis grown indoors with regard to potency (Caulkins, 2010). In order to differentiate the lower potency plants from the ones with a higher potency, a lab analysis for the content of psychoactive ingredients would need to be conducted.

While law enforcement officers undergo rigorous training in drug detection, they too sometimes have difficulty differentiating between higher potency marijuana and "ditchweed" or hemp. Most of the time, seized cannabis plants are eradicated without laboratory analysis for the content of psychoactive ingredients, based on the suspicion or belief that they are cannabis plants. Footnote 5 Thus, information on marijuana eradication efforts could be somewhat misleading because no proper differentiation between hemp, "ditchweed" and higher potency cannabis is being conducted, nor are low potency male plants distinguished from high potency female plants, even where this might be possible. Similar to the metric of illegal production and cultivation, it is impossible to compare eradication efforts across jurisdictions in Canada because, if reported, it only accounts for a number of plants or the amount of the eradicated product. However, as mentioned in Maslov et al. (2016: 17), "eradicating a hundred ‘ditchweed’ plants that are of no value to cannabis sellers or users is far from comparable to eradicating a hundred marijuana plants that are seized during a basement grow-op bust. What needs to be measured is the level of THC and other psychoactive ingredients that are being eradicated." It is impossible to conduct a lab analysis on every batch of cannabis that is about to be eradicated. However, just like with the potency metric, the samples that are already analyzed by DAS could be shared with researchers and policy makers, and a random sample of seized cannabis that is not part of the investigation could be analyzed for potency in order to understand what exactly is being eradicated.

An example of how the seizure and the subsequent eradication of seized marijuana could be misinterpreted can be seen in Kansas City in 2013. In that year, a 4,000% increase of marijuana seizures was reported compared to 2012 (Associated Press, 2013). A closer examination of the report reveals that this increase is largely based on two large-scale outdoor grow-ops busts that ended up being lower grade "ditchweed," and not higher potency cannabis. The Drug Enforcement Agency in the U.S. reports on their eradication efforts of seized cannabis differentiating between "ditchweed" and cultivated plants, supposedly indoors. Footnote 6 This is a good step towards differentiating between lower and higher potency cannabis that is being seized and eradicated by law enforcement.

A better approach for recording and reporting the seizure metric would make eradication metrics more useful and representative of the true portrait of eradication efforts. The number of eradicated plants carries little value unless differentiated by higher and lower potency plants, or fiber hemp, feral "ditchweed" and drug cannabis. Undifferentiated, raw data in the form of amount or number of plants is not easily comparable across jurisdictions in Canada and can result in false conclusions about the state of illicit cannabis in Canada.

Results from the CCJS consultation with selected police services indicate that about half of the police services interviewed collect information on illicit cannabis crop eradication. The information collected is for investigative and intelligence work. The data is somewhat limited in how it could be used beyond investigative work because the information is manually entered into the RMS and rarely analyzed post-investigation. The data could be shared with external partners upon request, again, for investigative purposes. No data on the eradication of illicit cannabis can be shared until the investigations are complete, and even then, the process of sharing this information is far from straightforward. If the police were to collect data on eradication efforts, changes such as more fields would need to be introduced in the RMS. However, the police believe that this is burdensome and would require additional resources.

Postal Services

One of the major ways to distribute cannabis—both licit and illicit—is through the mail. A simple Google search of terms "marijuana AND mail AND order AND Canada" will return numerous websites advertising their cannabis distribution services. These websites operate in a way that is very similar to online shopping websites such as or The seller would post the picture and description of the product and the asking price. During a transaction, the website user (buyer) would accept the asking price and anonymously pay for the product, while the seller would mail the package containing the product to the buyer. Licensed medical cannabis producers and users are used to this kind of exchange, with Canada Post providing guidelines on how to properly ship marijuana product (Sanderson, 2016). But some illicit marijuana is traded much in the same way within Canadian jurisdictions and across national borders.

Information on the transfer of cannabis products through mail, either within Canada or internationally, does not exist in Canada. Within Canada, this is because under the Canada Post Corporation Act, law enforcement does not have the authority to open packages until they have reached their final destination (Canadian Press, 2015). Police can obtain a warrant to seize packaged mail if there is a suspicion of a national security threat (Sanderson, 2016), which mailed marijuana packages would not pose. Furthermore, several law enforcement jurisdictions would need to cooperate in order to obtain a warrant to seize packages. This is time-consuming and labour intensive for the police to do, given other multiple priorities that they have. For international packages, the CBSA does not have the authority to open and inspect packages that weigh less than 30 grams (Canada Post, 2016). This allows for a more-or-less unimpeded transfer of up to an ounce of cannabis through international mail incoming to, or outgoing from, Canada. In early 2015, the CACP passed a resolution calling for a more streamlined process for the seizure of suspicious mail packages in order to better enforce laws (Canadian Association of Chiefs of Police, 2015: 24-26).

It is extremely difficult to obtain information on intercepted inland or international packages from the CBSA or RCMP. This information is confidential because of ongoing investigative work. It is only shared with the public as a result of an access to information request. The media could request such information to support a news story. For example, CBC reports that across the province of Quebec, the CBSA seized a total of 2,891 pieces of mail that contained illicit substances in 2015 (CBC, 2016, May 16).

Information from the state of Colorado, where the judicial system is somewhat different when it comes to mail, shows that there is an observable increase in seized packages that originated in Colorado and that were destined for other jurisdictions in the U.S. In 2009, there were no packages containing cannabis intercepted by the police. Since then, the number of seized packaged has been steadily rising, from 15 in 2010, to 207 in 2013, and to the highest of 581 in 2015 (Rocky Mountain, 2016: 127). The weight of seized packages containing cannabis products has also been rising from none in 2009, to 57.2 pounds in 2010, to 493.1 pounds in 2013, and to its highest of 1,246 pounds in 2015 (Rocky Mountain, 2016: 128). Finally, the number of U.S. states for which the parcels were destined has been rising from none in 2009, to 33 in 2013, and to its highest of 38 in 2014 (Rocky Mountain, 2016: 128).

Lack of data on the transfer of cannabis or other drugs through mail is problematic because multiple transfers occur through the mail, but none are (or can be) captured. No reports of transfers of cannabis through mail does not imply that no cannabis is being transferred. It also needs to be remembered that the number of seized packages, the amount of cannabis seized or the number of states for which the parcels were destined was not counted and recorded prior to 2009. It does not mean that the phenomenon did not exist, but that it was simply not recorded. Furthermore, similar to all other seizure-based metrics, increased vigilance in surveillance or proactive seizing activities will lead to increased numbers. Therefore, the enormous increases that are observed in the parcel services used for transfers in Colorado may be attributed, at least in part, to increased police activity in the area of seizures of parcels containing cannabis.

If legislative changes are introduced as per request from the CACP, and should the CBSA be authorized to seize mail or parcels that weigh less than 30 grams, it would be beneficial to begin collecting and promptly recording seizure data that feeds into the postal services metric. This data would provide valuable and much needed insight into the functioning of the cannabis market, both illicit and soon to become licit, should the respective legislation take place in the spring of 2017. The analysis of parcel data would greatly benefit from inclusion of a measurement of the level of resourcing for enforcement; the approaches taken by enforcement; the overall volume of mail for the time period under analysis; and the proportion of the items that were screened. These parameters should be accounted for (controlled) in the analytical models in order to determine whether there was a substantial increase in the transfer of marijuana through the mail.

Results from the CCJS consultation with selected police services indicate that very few police services out of those interviewed collect information on the transfer of cannabis using postal services. It is impossible to know what information is actually collected due to its confidential nature. Some police jurisdictions indicated that while, in theory, it is possible to collect such information, changes to the RMS and UCR would need to be introduced.

Diversion between Markets

Diversion of cannabis may be occurring for several reasons, including avoidance of paying excise, avoidance of regulatory frameworks, or better profits when diverted outside of the jurisdiction of origin. Another important dimension of the diversion of cannabis is that although Canada is projected to have some sort of a legalized cannabis regime, and some bordering US states will have legalized regimes, cannabis-associated trade may not be simple or even possible, due to US federal laws and/or international treaties.

Diversion of cannabis may be occurring is several forms. It could occur between: 1) markets segmented by regulation (i.e., medical and non-medical); 2) markets within a country segmented by political geography (i.e., by province); and 3) international markets segmented by political geography (i.e., by country, treaty or trade bloc). As such, the discussion of the metric of diversion will be divided into two parts: 1) diversion for the purpose of internal trade (i.e., within jurisdiction); and 2) diversion for the purpose of exportation.

Internal Trade

Cannabis that is grown and produced in one jurisdiction needs to be transported (diverted) to the next stage of the supply chain, possibly to another jurisdiction. The issue becomes even more evident when there are different cannabis regimes functioning in the same jurisdiction, such as the current differential provincial regulations of tobacco and alcohol. For example, Canada currently has a legalized medical marijuana regime, whereby the use of cannabis for any other purposes is illegal under the Criminal Code. A Supreme Court ruling in February, 2016, in Allard v. Canada paved the way for medical marijuana users who hold licences to grow their own cannabis at home. Some of the cannabis that is obtained through a medical licence or grown at home under the medical licence could, supposedly, be diverted, resold or shared for free with people who do not have a medical licence to use cannabis (Smitherman, 2016). In the U.S., where some of the states have a full legalized cannabis regime, some cannabis is being diverted to other states that do not have a legalized cannabis regime (Ellison and Spohn, 2016). The metric of diversion then measures the amount of cannabis that is diverted to other jurisdictions or from the medical license holders to people without such a licence.

No data exists on the diversion of cannabis between jurisdictions, or from medical cannabis licence holders to other people in Canada. Some anecdotal evidence on diversion from the medical marijuana market is mentioned in the media (see Barghout, 2016), but there are no nationally representative statistics available. Colorado, on the other hand, has been collecting comprehensive information on diversion of cannabis out of state since at least 2005. Seizures of diverted cannabis, also called interdiction seizures, have seen an increase since the commercialization of medical use of cannabis in 2009. In that year, there were 92 interdiction seizures executed by the police, rising to 321 in 2011, decreasing to 274 in 2012, and peaking at 394 in 2015 (Rocky Mountain, 2016: 110). The average weight of total interdiction seizure increased about 30% from the period 2005–08 to 2009–15, from 2,763 to 3,586 pounds (Rocky Mountain, 2016: 111). About two-thirds (65%) of diversion seizures originated in the city of Denver (Rocky Mountain, 2016: 112). Several case examples have illustrated how interdiction seizures are performed and their outcomes.

The Rocky Mountain (2016) report on cannabis metrics in Colorado is a good example of how the diversion of cannabis and several other seizure-based metrics can be collected, used and analyzed in a clear and concise manner. The process of data collection on the diversion of cannabis is neither easy, nor straightforward. It requires the prompt reporting and recording of police data that is confidential due to ongoing investigations. It also requires the police to report on this data to a central database or to researchers. Police jurisdictions would also need to communicate with each other in order to coordinate the data recording and reporting in order to avoid the double-counting of interdiction seizures. All these tasks are undoubtedly time-consuming and cumbersome. However, the end result shows the potential for a solid trend analysis in diversions of cannabis out of Colorado, which would in turn help policy makers and law enforcement make better decisions in terms of resource allocation and prioritization of activities. Furthermore, with the appropriate combination of metrics regarding cannabis price and seizure-based metrics, researchers can better study the overall functioning of the cannabis market.

As is the case with all other seizure-based metrics, it must be remembered that the diversion of cannabis to other jurisdictions is based solely on the number of seizures that are executed by the police. The number of seizures depends heavily on the resource allocation and prioritization that is allotted for drug enforcement activities.

Results from the CCJS consultation with selected police services indicate that none of the police services interviewed collect information, or plan to collect information in the future, on diversion of cannabis to other jurisdictions. Respondents did not see the collection of this sort of data as a priority. The information that feeds into this metric would constitute investigative work. Some police jurisdictions indicated that in order to collect data on diversion of cannabis to other jurisdictions, changes to the RMS and UCR would need to be introduced.


Cannabis plants grown and cannabis products produced in Canada are exported outside of Canada and sold in international markets. UNODC (2016) reports that the amount of cannabis produced in Canada exceeds the domestic demand. The majority of cannabis products that are transported through the Canada–U.S. border are destined for the U.S. (Public Safety Canada, 2010: 6). Time magazine further reported in 2004 that about 90% of the commercially-grown cannabis in Canada ends up being distributed in the U.S. market, where its estimated street value was between $5 and $25 billion (Hamilton, 2004). No details on the calculation of the proportion of Canadian-grown cannabis or the street value of the exported cannabis products in the report were shared. The RCMP estimated that between 50% and 80% of cannabis grown in BC was destined for U.S. markets (Surrey, 2009). This estimate was supported by Larsen (2011), who estimated the proportion of BC-grown cannabis exported to the U.S. at 70%. No details were provided on the strains, potency or type of cannabis products that were exported from Canada to the U.S.

These statistics, while striking, represent an important gap in the data on the exportation of Canadian-produced cannabis outside of Canada. They appear to be one-time estimates, with little or no details provided on the source of the data or the methodology used to develop the estimates. In part, this is likely due to the confidential nature of the data and the lack of consistent reporting mechanism for the data on cannabis seizures at the border.

The CBSA is responsible for enforcing the law at the Canadian border and, in theory, could be collecting on the type of data that could be used to track the metric of exportation of cannabis out of Canada. However, the Office of the Auditor General of Canada (2015: 3) found that the CBSA "did not fully have what it needed to carry out its enforcement priorities, due to weaknesses in its export authorities, information, practices, and control." Limited authority is partly responsible for the inadequate prevention of the export of illegal drugs from Canada. Illegal drugs were not identified as an organizational priority in the Auditor General’s report due to the CBSA’s authority constraints. The audit of the CBSA highlights problems using the data for the number of reported seizures of cannabis at the border, the capacity of organization at entry/exit points, and the variation of procedures by air, water transport and cargo (Office of the Auditor General, 2015). Caution is needed in using the metric of cannabis seizures by border patrol services, as it is likely to be underrepresented.

Additionally, it is common knowledge that when travelling to the U.S. from Canada in a private vehicle, the driver and the passengers would be greeted by the U.S. Customs and Border Protection officer at the border crossing point, not the CBSA. As such, seizures of the cannabis products that are exported from Canada to the U.S. would be carried out by the U.S. jurisdiction. Data on seizures at the border is shared between the U.S. and Canadian border jurisdictions to a limited extent. However, this data is confidential, not public, and can only be accessed through an access to information request.

Aside from actual statistics on cannabis seizures at the border, methods exist for estimating the amount of cannabis or other drugs exported out of Canada. Bouchard et al. (2012), for example, suggested a method for estimating the amount of methamphetamine and MDMA that is exported out of Canada through subtracting the amount of drugs consumed in Canada from the amount of drugs produced to estimate net exports. A similar method of estimating the size of the market for contraband tobacco in Canada, called the Data Confrontation Method, was proposed in Maslov and Boucher (2014). While in theory, this difference could be attributed to export of the drugs, there are too many other variables that need to be taken into account before concluding that the difference may be attributed solely to export. First, solid production and consumption rates for cannabis are not readily available in Canada; only estimates based on several assumptions exist. Second, the estimates for consumption or cannabis are likely underrepresented, as is the case with most illicit or socially undesirable activities, because they are usually based on self-reported rates (Bjerregaard and Becker, 2013; Fendrich et al., 2004; Hser, 1997; Mieczkowski, 1989; O’Malley et al., 1983). Finally, the importation of goods into Canada is rarely taken into account in these models, which would certainly skew the final estimates.

It is very important to measure the amount of cannabis exported from Canada because of its contribution to seizure-based and other metrics. All cannabis seized at the border will be destroyed, and the potency of the seized products could be determined—both of which are seizure-based metrics identified in this paper. Properly measuring the metric of cannabis at the border could also assist in understanding the size of the cannabis industry in Canada, both domestic and international. Law enforcement agencies’ investigative work on the extent of involvement of organized crime in the cannabis and other drug industries in Canada could be greatly expanded using the cannabis exportation metric. As is the case of the metric of diversion to other jurisdictions, a combination of metrics measuring the use of cannabis, price and other seizure-based metrics, researchers can better study the overall functioning of the cannabis market. The limitation of law enforcements’ priorities and resource allocation applies to the metric of exportation of cannabis, just like it does to all seizure-based metrics.

Market Estimates

The study of the cannabis consumer market could benefit from good cannabis seizure data. The classic approach to studying consumer markets is to assess the supply and the demand of consumer goods. In the example of cannabis, the demand side of the equation may be assessed by measuring the consumption of cannabis in the population under study through frequency, intensity and amount of cannabis consumed. The supply side of the equation may be assessed through tracking the price for which cannabis products are sold in a population. Footnote 7 However, a proper measurement of cannabis seizures could be an excellent addition to the measurement of the supply of cannabis to the market. While it would have certain limitations such as the police resource allocation and prioritization, it would, if properly measured, provide the actual quantity of cannabis that is supplied to the consumer market.

The idea of measuring the supply side of the equation in cannabis market estimates is further exemplified by RAND economists (Kilmer et al., 2013). In their major paper on the overview of the state of the cannabis market in Washington state before the legalization of recreational use of cannabis, the researchers argue the importance of incorporating the seizure-based metrics in the economic equations of supply and demand (ibid: 3, 9). Bouchard and colleagues (2012) also used seizure-based metrics to estimate the size of the methamphetamine and MDMA market in Canada. There are other arguments whereby properly measuring seizure data as a supply-side indicator in drug markets will help "promote comprehensive understanding, to facilitate transfer of scientific findings to effective practices, and to strengthen the evaluative quality of drug policies" (Leone et al., 2012, p. 741).

However, one must have accurate data with which to construct production estimates in order to apply seizure data to the issue of market size. Prior to 2010, seizure data was routinely used to estimate the amount and value of cannabis drug markets. This was true of illicit domestic markets, as well as the development of global estimates, such as those disseminated by the UNODC in their annual World Drug Report. In the mid-2000s, the UNODC estimated the "interception rate" (i.e., volume of seizures/volume of production) for reporting countries to be an average 10 to 20% for herbal cannabis and plants, and at least 17% for cannabis resin products (UNODC, 2008). For many police, members of the media and policy makers, the lower bounded estimate of 10% came to be used as the "rule of thumb" when estimating the amount of domestic production, in the absence of any other data aside from seizure data. Therefore, in 2008, Canada was estimated to have produced 1,300 to 3,498 metric tonnes of cannabis; this was extrapolated directly from seizure data. There were a number of methodological difficulties with this approach (UNODC, 2015). The first problem was that the data used to accurately estimate production volume was only available from certain countries, which did not include Canada and which did not share the same production and consumption characteristics as Canada. The second problem was that interception rates, and seizures, are closely related to law enforcement strategies and investments. Thus, it cannot be assumed that an expansion of seizures equates to an expansion in production, when it could be related to an expansion in enforcement efforts or effectiveness. Using this logic, if law enforcement stopped investigating cannabis offences, production would cease, too; which is patently absurd. The UNODC stopped using seizures to estimate the size of cannabis production in 2010, partly for these reasons. Since 2010, data to establish production estimates in many countries, including Canada, has not been available. Thus, while the UNODC can estimate the production of cocaine and opioids (UNODC, 2015), as of the 2016 World Drug Report, there is no solid estimate for global cannabis production.

Organized Crime

The role of organized crime in cannabis and other drug markets has been mentioned throughout this report. It is extremely hard to study the patterns of organized crime activities in a society due to its hidden nature. Researchers and policy makers often rely on estimates when it comes to scoping organized crime activity (see Bouchard et al., 2014; Munch and Silver, 2017). Because of law enforcements’ investigative work and other estimates, it is understood that organized crime elements play a major role in the production, trafficking and selling of cannabis and other drugs in Canada. A search on Google using the terms "drug seizure AND organized crime" will result in dozens of media articles discussing police raids on drug production sites or the busting of a trafficking ring, the products seized and the value of the seized products, weapons and other properties.

The array of seizure-based cannabis metrics discussed throughout this paper could contribute immensely to the study of the scope of organized crime. Seizures of cannabis, especially in large quantities, could be, and usually are linked to investigative police work. These investigations often lead to discovering and disrupting an organized crime ring, which is the main approach of law enforcement in combatting organized crime (CISC, 2014). Media articles that appear as a result of a Google search are prime examples of these investigations. However, these investigations are the result of reactive policing, whereby police react to an already existing phenomenon. The root metric of cannabis seizures is a strategic disruption tool, and thus an important performance metric of the effectiveness of law enforcement in disrupting organized crime activity.

On the other hand, if cannabis seizure-based metrics could be properly collected, recorded and analyzed, researchers could build powerful predictive models that not only estimate the involvement of organized crime in the cannabis market, but also predict the scope and prospective activities of the criminal elements. There are already good examples of these models in the literature (see Buscaglia and van Dijk, 2003; Morselli, 2014; von Lampe, 2003); what is needed are good data on seizure-based metrics.


Information that could potentially contribute to the data needs for seizure-based cannabis metrics is currently collected under a number of different authorities in Canada. These include the CBSA, municipal and provincial police jurisdictions, the RCMP, and HC. Four major databases keep information on seizure-based metrics: 1) ICES (CBSA-administered); 2) CDSD (HC-administered); 3) LIMS (HC-administered); and 4) RMS systems (municipal and provincial police jurisdictions and the RCMP).

This paper presented an overview and a critical assessment of the way cannabis seizure data is collected, recorded, reported and shared in Canada. A thorough literature review was conducted along with consultations with federal partners from the fields of operations, policy and education on the way they understand and execute seizures of illicit cannabis. Several strategic recommendations were provided as a result of the work conducted for this project. These include conceiving better ways to link seizure-based data; inter-operationalizing different systems of collecting seizure data (i.e. ensuring that the systems do not double-count or omit seizure data); creating a central point of contact to access the data; formalizing partnerships for a more straightforward data accessibility; and considering approaches for reconciling the data that is being transferred between partners. Several other suggestions for the enhanced counting of seized cannabis products and recording of seizure information were provided.

While Canada is undergoing a historic process of legalizing the recreational use of cannabis, it is important to remember that the illicit market for cannabis may not entirely disappear post-legalization. Illicit production and trafficking of cannabis may still exist after the legalization. Diversion to jurisdictions within Canada or internationally, where cannabis regimes would be different from the future one in Canada’s provinces and territories, which may choose to design their own specific cannabis regime (e.g. times of sales, legal age for access, home growth, consumption in public, etc.) might still be occurring. Regulatory and criminal offences, such as the existing ones for tobacco and alcohol, will likely be occurring with legalized cannabis. All of these illicit cannabis-related activities could result in seizures of cannabis by law enforcement. As such, it is important to have a properly set up system of collection of seizure-based data, both pre- and post-legalization because good seizure-based cannabis metrics are one of the major elements required for studying the cannabis market in terms of use, diversion, grey and black markets, organized crime activity and econometric estimates. Having a solid system for collecting seizure data set up in Canada will fill the gap of baseline and trend seizure data. The case of Colorado (Rocky Mountain, 2016) is a good example of how seizure-based metrics can be reported and tracked for research and policy adjustments over time.

It will be important to consider the role cannabis seizure data will continue to play under a different regime in Canada. Existing data sources may not be adequate, as seizure metrics are captured in locations and by partners that are not regularly included. Current seizure metrics by existing partners may need to be adapted as we move from gathering baseline data towards understanding the impact and context over time. Data from sources outside of the current cannabis seizure enforcement model may need to be supplemented by data from administrative or regulatory sources, which will require new partnerships. This may introduce new concerns or highlight existing ones for data sharing. Moreover, differences between adjacent jurisdictions may emphasize discrepancies between cannabis regimes and will need to be taken into consideration when establishing and updating the framework of cannabis metrics that are needed by researchers and policymakers alike.


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Appendix A: Controlled Drugs and Substances Act, Schedule II

SCHEDULE II (Sections 2, 3, 4 to 7, 10, 29, 55 and 60)

    Cannabis, its preparations and derivatives, including

Appendix B: Integrated Customs Enforcement System (ICES) Database Seizure Fields

  1. Seizure number
  2. Date and time of seizure start/end
  3. Referral type (i.e. intelligence target)
  4. Status of seizure (i.e. open, appealed, closed)
  5. Location where seizure is made (port of entry, region)
  6. Officers involved in seizure (names, badge numbers)
  7. Contact information on individuals involved in the seizure (or importers/exporters as the case may be):
  8. Full name
  9. Date of birth
  10. Address
  11. Phone number
  12. Passport number
  13. Gender
  14. Country of origin
  15. Citizenship
  16. Country of birth
  17. Employment status
  18. The substances seized separated by type, category
  19. Quantities seized
  20. Tariff codes
  21. Estimated value
  22. Vehicle type involved in the seizure (i.e. aircraft type, airline, car, tractor trailer)
  23. Detection technology used in the seizure
  24. Indicators that led to the seizure (i.e. nervousness in the traveller, smell)
  25. A detailed seizure narrative on the proceedings (i.e. when rights were read to travellers, when they called a lawyer, when samples were sent to the lab, what the lab response was, etc.)

Appendix C: Controlled Drugs and Substances Act Database (CSDS) Seizure Fields

  1. The case-id number
  2. Police file number
  3. Police rep number
  4. Police name
  5. Municipality
  6. Province
  7. Type (e.g., RCMP)
  8. Date of the seizure
  9. Drug generic name (e.g. Oxycodone)
  10. Drug name (e.g. Oxycontin 5mg SRT)
  11. Drug strength
  12. Drug strength unit
  13. Quantity
  14. Seizure unit
  15. Destruction confirmation date

Appendix D: Laboratory Information Management System (LIMS) Database Seizure Fields

  1. Receiving lab (which lab received the exhibit)
  2. Analyzing lab (which lab did the analysis)
  3. Sample number
  4. Police province
  5. Received date (corresponds to the date first received by the lab, which is the same for the lab that received and lab that analyzed it)(date the laboratory received the exhibit)
  6. Suspected drug code (what the law enforcement agency thinks the substance is)
  7. Actual drug code Footnote 8 (the substances found in the exhibit)
  8. Drug Act code (whether it was CDSA, Food and Drug Act or other)
  9. Drug schedule (which schedule of the CDSA it is under)

Appendix E: RCMP Records Management System (RMS) Seizure Fields

Tab 1: Drug

  1. Type (e.g. cocaine)
  2. Value
  3. Common name
  4. Quantity
  5. Estimated quantity
  6. Form
  7. Remarks

Tab 2: Property involved in occurrence

  1. The classification (Only seizures classified as "disposal approved", "evidence", "found", "held", "seized", "seized with warrant", and "other" will be included in the report)
  2. The date the drug was seized (Effective from – this field is auto-generated)
  3. ID # (optional)
  4. The type of drug (if not prefilled through search function)
  5. Remarks (optional)
  6. Recovery time (optional)
  7. Damage value (optional)
  8. The quantity of the drug (the quantity can be changed from the default "1" by clicking on the field and typing the appropriate quantity)
  9. The value of the drug (in Canadian dollars)
  10. Common name (optional)
  11. Estimated quantity (optional)
  12. Form (optional)
  13. Colour (optional)

Tab 3: Uniform Crime Reporting Survey (UCR)

  1. Provincial code
  2. Location code

Appendix F: Health Canada, Drug Offence and Disposition Report

The figure depicts the SC/HC 3515 Drug Offence and Disposition Report, which must be completed and submitted the Office of Controlled Substance and Drugs for authorization to destroy seized cannabis (or other illicit substance). SC/HC 3515 includes 45 fields, requiring details on the illicit substance seizure, defendant, offence and disposition of charges, controlled substances to be destroyed, and police service.

Appendix G: Canadian Police Knowledge Network (CPKN) Curriculum Outline

Report Writing

Upon completion of this course you will be able to:

  • Evaluate your report writing and either list or make improvements
  • Paraphrase the importance of writing clear and concise reports
  • Explain the complexity of writing reports and the volume of writing officers complete on a daily basis
  • Discuss how your investigative abilities are expressed through your report writing
  • Recognize the link between your notes and your report writing
  • Identify potential issues that pose an ethical issue
  • Discuss the police report pathway
  • Assess your investigation using the Evidence, Belief, Action (EBA) cycle
  • Use the EBA cycle to analyze evidence, form your beliefs, and take the appropriate actions
  • List all necessary information in your report
  • List all charges, the count, criminal code section, date, time, and place
  • Provide and describe any evidence to support your charge(s)
  • List all persons involved (civilian and sworn)
  • Describe the involvement of all persons listed (civilian and sworn)
  • Complete an investigative summary by including information about who, what, where, why, and the elements of the charge
  • Recall that reports are read and reviewed by others
  • Evaluate your reports and determine whether or not they are complete
  • Apply the Goals, Objectives, Strategies (GOS) model to report writing
  • Recall that reports need to be concise, accurate, and logical
  • Demonstrate the GOS model by writing quickly and include a lot of information in a way that is easy to understand
  • Construct a clear and concise report that is chronological in order
  • Construct a report that links the events to the charges
  • Construct a report that describes the events in chronological order
  • Construct a report that articulates the occurrence clearly for the reader
  • Apply the Relevance, Structure, Precision (RSP) model
  • Apply strategies to improve the quality of your report
  • Apply grammatical strategies to improve the quality of your writing
  • Use information in the module to further improve writing skills
  • Use information to further develop investigative knowledge

Appendix H: Canadian Police College (CPC), Drug Investigative Techniques (DITC) Course

Drug investigations differ from traditional criminal investigations as they deal with crimes as they occur. In most cases, the suspects are already identified and the purpose of the investigation is to build a prosecutable case against the suspect, identify other members involved in the drug trafficking organization and seize as many drug-related assets as possible.

This ten-day course is aimed at officers with limited experience in drug offence investigations. The course content follows the natural progression of a drug investigation, which includes classroom lectures combined with exercises that imitate a drug investigation.

The course provides the participants with the knowledge and skills required to improve their capacity to successfully investigate drug files. It is also structured to help participants improve their interpersonal skills to facilitate work in a team environment focused on a common end result.

Selection Criteria

This course is open to:

  • All law enforcement officers who have limited experience in drug investigations, whether they work in a plain clothes unit or are assigned to uniform duties.

Priority will be given to officers who have recently been transferred (or who will soon be transferred) to a unit whose main responsibility is to investigate drug offences.

Note to Unit Commanders / Supervisors

The DITC is a basic drug course. It is intended for officers who have limited experience in drug investigations. All officers are encouraged to apply for this course whether they work on a plain clothes unit or in uniform (patrol) duties.

This provides the opportunity to have trained drug investigators within your services who can be called upon to assist drug units when the need arises. The course can also contribute to minimize the transition period for those who transfer to drug units ("Hit the ground running" theory).

In the past, participants who have attended the DITC had a wide spectrum of experience, from junior officers with no knowledge of drug work to subject matter experts in drug investigations. This has caused two issues:

  • Junior members were reluctant to fully participate in the course as they are intimidated by those who have more experience;
  • Expenditures of resources (time and money) on experienced officers who received very little out of a three week long course.

The feedback received from course participants still supports that the DITC, as designed, continues to meet the needs of those with limited drug investigations experience.

Limited experience, what does that mean?

By limited experience we suggest:

  • Officers, who have no knowledge, or who are starting to investigate drug offences;
  • For those who are currently working in drug sections, we recommend that they have been doing so for under two years, and have not received any form of drug or covert investigative training i.e.: surveillance course, source and handling course;
  • The amount of service is not important; therefore, senior officers are encouraged to apply for the DITC if they do not have any drug investigation experience.
  • Each applicant will be assessed individually.

Course Objectives

By the end of this course, participants will be able to:

  • demonstrate their ability to handle and recruit sources by applying principles learned through scenarios;
  • recognize the involvement of organized crime in illegal drug activities;
  • discuss ways to prepare for court;
  • explore a variety of drug investigative practices and techniques;
  • discuss how major case management principles can be applied during a drug investigation;
  • explore different types of clandestine laboratories such as synthetic drugs and Marijuana grow operations; and
  • examine the legal requirements for search and seizure.


  • Human sources
  • Clandestine laboratories overview
  • Criminal organizations
  • Search warrants
  • Court preparation and testimony
  • Officer safety
  • Investigative techniques and practices
  • Partners
  • Major case management
  • Proceeds of crime

Appendix I: Canadian Police College (CPC), Advanced Drug Investigative Techniques Course

Drug investigations continue to become more complex due to factors such as court decisions, technology advancement and the sophistication of organized crime groups.

The Advanced Drug Investigative Techniques Course is designed to provide current training in areas such as recent case law, agent led investigations, new drug trends, organized crime trends, assets investigations, and high risk operational planning.
This five day course is aimed at experienced officers who currently are involved in drug offence investigations. The course content will focus on three core components.

  • Legal Applications
  • Covert Operations
  • Assets Investigations

Course participants will have the opportunity to identify their current challenges in these three areas by completing a pre-course questionnaire, and in a small group setting will have the opportunity to discuss their issues with a Subject Matter Expert, their issues, and collaboratively identify possible solutions.

Selection Criteria

  • Experienced investigators who have not received any drug investigational training during the past three years;
  • Priority will be given to officers who are currently involved in the expert witness program or who are working towards achieving that designation.
  • Must have successfully completed their departments / forces recognized source management and surveillance training.

Course Objectives

By the end of this course, participants will be able to:

  • demonstrate leadership skills required to positively impact both the outcome of an investigation and the work environment of a drug unit;
  • articulate recent case law related to investigative techniques used in complex drug investigations;
  • manage covert operations; and
  • acquire functional knowledge in the area of Assets Investigations.


By the end of this course, participants will be able to:

  • demonstrate leadership skills required to positively impact both the outcome of an investigation and the work environment of a drug unit;
  • articulate recent case law related to investigative techniques used in complex drug investigations;
  • manage covert operations; and
  • acquire functional knowledge in the area of Assets Investigations.

Appendix J: Canadian Police College (CPC), Clandestine Laboratory Investigations (CLIC) Course

Clandestine laboratories present numerous hazards to law enforcement personnel, the public and the environment. Extreme potential for fires, explosions and exposure to hazardous chemicals and fumes are but a few of the possible dangers. This [eight]-day course provides participants with the skills, knowledge and investigative techniques essential to successfully investigate and safely dismantle clandestine laboratories. It also enhances the professional approach to clandestine drug investigation.

Selection Criteria

This course is open to:

  • police officers who are or are going to be assigned to a full time specialized unit mandated to investigate drug offences or who are or are going to be involved in the investigation of clandestine laboratories.

Potential participants who have successfully completed CPC’s Drug Investigative Techniques Course (DITC) are given preference.

Note: This course includes practical exercises that require physical exertion. Therefore, participants must be physically fit and exempt of any respiratory conditions that would preclude them from using respiratory equipment.

Prerequisite (optional): Potential participants who wish to familiarize themselves with CBRN (chemical, biological, radiological, nuclear) content and common terminology used when faced with a CBRN incident are invited to explore the following website: (Search Canadian Emergency Management College). Once on the Canadian Emergency Management College site, click "Programs" under "The College" heading, and click on "CBRN First Responder Training Program". The two courses recommended are:

  • Awareness course
  • Basic level course

Both of these courses are free of charge and available via e-learning.

Course Objectives

By the end of this course, participants will be able to:

  • identify various types of clandestine laboratories and their related components;
  • apply various investigative techniques associated with the investigation and dismantling of a clandestine laboratory;
  • select the appropriate level of personal protective equipment required during the various stages of the clandestine laboratory processing operation;
  • employ appropriate safety procedures associated with the investigation and dismantling of a clandestine laboratory;
  • use investigative, legislative and prosecutorial tools available to investigate, secure and dismantle a clandestine laboratory; and
  • apply dismantling techniques to properly and safely tear down, collect and preserve evidence from a clandestine laboratory.


  • History and types of clandestine laboratories
  • Incident Management Systems (IMS)
  • Investigative techniques
  • Officer safety
  • Personal protective equipment
  • Laboratory dismantling

Appendix K: Drug Analysis Service (DAS), Client Manual, "When to Submit Exhibits"

Section 1.2 When to Submit Exhibits

In order to manage requests for analysis, the DAS asks for your assistance when submitting exhibits.

Here are some questions you should ask yourself before submitting exhibits. If you answer “No” to any of these statements, it would be better to reconsider sending the exhibits in question.

  • I need an analysis result to press charges
  • The suspect enter a plea of not guilty
  • Charges will be laid
  • For samples from the same case, I have made a selection (depending on) the quantity, nature…) of the samples to be analyzed
  • When it comes to tablets, I have eliminated the possibility that it is over the counter pharmaceutical tables
  • When the nature, quantity and chain of possession of a substance are admitted by the defense, it is still necessary to conduct the analysis
  • For quantitative analysis, the request is well founded and supported by my supervisor

Submit your exhibits early enough to ensure they are analyzed in time for court.

If the analysis is urgent and results are required immediately, contact the laboratory to inform them and to ensure the analysis can be completed in time.

If a plea has been changed to guilty after exhibits are submitted, contact the laboratory and request that analysis be cancelled.

DAS Client Manual > 11


The terms "cannabis" and "marijuana" are used interchangeably throughout this report. Unless otherwise specified, both of the terms refer to the plants Cannabis sativa, Cannabis indica, Cannabis ruderalis, or their hybrids.

NDS includes information on cannabis seizures from the three RMS operated by RCMP only. As such, the NDS includes seizure data for all of Canada. Other law enforcement agencies in Canada maintain their own cannabis seizure data.

Previous attempts to graph the number of seizures of illicit drugs were unsuccessful due to inconsistency in labelling. For example, hundreds of opium pipes, bowls, and stems were reported as seized in the 1920’s. By 1937, this number had fallen to practically zero (Carstairs 2000, p77p. 77–78).

"Marihuana" is an archaic, anglicized spelling of the common Spanish colloquial name for psychoactive cannabis, "marijuana." The spelling is sometimes used in Canadian formal and legal records, as an artifact of older official usage.

For a detailed discussion on different ways of measuring supply and demand in cannabis markets, see Boucher et al. (2013).