Basic Data

(Marijuana Use Prevalence 2011) "In 2011, marijuana was the most commonly used illicit drug, with 18.1 million current users. It was used by 80.5 percent of current illicit drug users. About two thirds (64.3 percent) of illicit drug users used only marijuana in the past month. Also, in 2011, 8.0 million persons aged 12 or older were current users of illicit drugs other than marijuana (or 35.7 percent of illicit drug users aged 12 or older). Current use of other drugs but not marijuana was reported by 19.5 percent of illicit drug users, and 16.2 percent of illicit drug users reported using both marijuana and other drugs."

(Marijuana Use Estimates by State) "Marijuana, the most commonly used illicit drug, was used by 6.0 percent of the population in 2007-2008 during the past month (Table B.3). States showing high prevalence rates for illicit drug use also had high prevalence rates for past month use of marijuana. Of the 10 States in the top fifth for past month use of an illicit drug among persons aged 12 or older, 9 States also were ranked in the top fifth for past month marijuana use: Alaska, Colorado, District of Columbia, Montana, New Hampshire, Oregon, Rhode Island, Vermont, and Washington (Figures 2.1 and 2.9).
"Seven States that ranked in the top fifth for past month marijuana use in all three age groups (12 to 17, 18 to 25, and 26 or older) and among persons 12 or older were Colorado, Maine, Montana, New Hampshire, Oregon, Rhode Island, and Vermont. (Figures 2.9 to 2.12). Iowa had the lowest rate of past month marijuana use in 2007-2008 (3.2 percent) in the 12 or older population, and Rhode Island had the highest rate (10.9 percent) (Table B.3)."

(Early Initiation of Substance Use) “When initiation of substance use occurs in preadolescence or early in adolescence, the risk of addiction is magnified.⁸ CASA’s analysis of national data finds that individuals‡ who first used any addictive substance before age 15 are six and a half times as likely to have a substance use disorder as those who did not use any addictive substance until age 21 or older (28.1 percent vs. 4.3 percent).”

(Disapproval of Marijuana Use) "The proportion of students seeing great risk from using marijuana regularly fell during the rise in use in the 1970s, and again during the subsequent rise in the 1990s. Indeed, at 10th and 12th grades, perceived risk declined a year before use rose in the upturn of the 1990s, making perceived risk a leading indicator of change in use. (The same may have happened at 8th grade as well, but we lack data starting early enough to know.) The decline in perceived risk halted in 1996 in 8th and 10th grades; the increases in use ended a year or two later, again making perceived risk a leading indicator. From 1996 to 2000, perceived risk held fairly steady and the decline in use in the upper grades stalled. After some decline prior to 2002, perceived risk increased in all grades through 2004 as use decreased. Perceived risk fell after 2004 and 2005 in 8th and 12th grades respectively, (and since 2008 in 10th grade) presaging the more recent increase in use. In 2011 perceived risk continued to decline in grades 10 and 12 and leveled in grade 8."

(Survey Support for Sales) "Asked whether they thought it should be legal to sell marijuana if it were legal to use it, about three in five (62%) said “yes.” However, about 80% of those answering “yes” (51% of all respondents) would permit sale only to adults. A small minority (11%) favored the sale to anyone, regardless of age, while 28% said that sale should not be legal even if use were made legal, and 10% said they “don’t know.”"

(Marijuana Use Among 50-Year-Olds in 2011) "Among 50-year-old high school graduates in 2011, we estimate that about three-quarters (76%) have tried marijuana, and that about two thirds (65%) have tried an illicit drug other than marijuana. (These estimates are adjusted to correct for panel attrition, as described in chapter 4 of Volume II.)
"Their current behavior is far less extreme than those statistics might suggest, but it is not by any means negligible. One in nine (11%) indicates using marijuana in the last 12 months, and the same proportion indicate using any other illicit drug in the same period. Their past-month prevalence rates are lower—5.9% and 4.3%, respectively, for marijuana and any other illicit drug. About 1 in 43 (2.3%) is a current daily marijuana user, though substantially more indicate that they have used marijuana daily at some time in the past."

Note: The Monitoring the Future survey also provides daily marijuana U.S. usage estimates by age categories to age 30. Following is the prevalence of daily use reported in 2011:

^{Age
19-20 = 6.6%
21-22 = 6.3%
23-24 = 6.9%
25-26 = 5.8%
27-28 = 4.6%
29-30 = 3.7%}

(Cannabis and Dependence) "People who develop problems with marijuana may indeed be different from those who do not, but this phenomenon has been observed with other substances of abuse. A comparison with alcohol use and dependence provides a case in point. The great majority of Americans have tried alcohol and continue to drink alcoholic beverages regularly. However, only an estimated 10 to 15 percent of alcohol drinkers develop problems, and only some of these problem drinkers seek treatment. This is also true of those who have tried cocaine or heroin (Anthony, Warner, and Kessler, 1994).
"That said, the experience of dependence on marijuana tends to be less severe than that observed with cocaine, opiates, and alcohol (Budney, 2006; Budney et al., 1998). On average, individuals with marijuana dependence meet fewer DSM dependence criteria; the withdrawal experience is not as dramatic; and the severity of the associated consequences is not as extreme. However, the apparently less severe nature of marijuana dependence does not necessarily mean that marijuana addiction is easier to overcome. Many factors besides a drug’s physiological effects—including availability, frequency and pattern of use, perception of harm, and cost—can contribute to cessation outcomes and the strength of addiction. The low cost of marijuana, the typical pattern of multiple daily use by those addicted, the less dramatic consequences, and ambivalence may increase the difficulty of quitting. Although determining the relative difficulty of quitting various substances of abuse is complex, the treatment literature reviewed here suggests that the experience of marijuana abusers rivals that of those addicted to other substances."

(IOM Report re Gateway Theory) In March 1999, the Institute of Medicine issued a report on various aspects of marijuana, including the so-called Gateway Theory (the theory that using marijuana leads people to use harder drugs like cocaine and heroin). The IOM stated: "There is no conclusive evidence that the drug effects of marijuana are causally linked to the subsequent abuse of other illicit drugs."

(Estimated Prevalence of Cannabis Dependence) "Some 4.3 percent of Americans have been dependent on marijuana, as defined in the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, Text Revision (DSM-IV-TR; American Psychiatric Association, 2000), at some time in their lives. Marijuana produces dependence less readily than most other illicit drugs. Some 9 percent of those who try marijuana develop dependence compared to, for example, 15 percent of people who try cocaine and 24 percent of those who try heroin. However, because so many people use marijuana, cannabis dependence is twice as prevalent as dependence on any other illicit psychoactive substance (cocaine, 1.8 percent; heroin, 0.7 percent; Anthony and Helzer, 1991; Anthony, Warner, and Kessler, 1994)."

(Prevalence of Cannabis Use Disorder) "The number of persons who had marijuana dependence or abuse did not change significantly between 2002 (4.3 million) and 2011 (4.2 million) or between 2010 (4.5 million) and 2011 (Figure 7.3). The rate of persons who had marijuana dependence or abuse in 2011 (1.6 percent) was lower than the rates in 2002 (1.8 percent) and 2004 (1.9 percent), but was similar to the rate in 2010 (1.8 percent)."

(IOM Report re Gateway Theory) The Institute of Medicine's 1999 report on marijuana explained that marijuana has been mistaken for a gateway drug in the past because "Patterns in progression of drug use from adolescence to adulthood are strikingly regular. Because it is the most widely used illicit drug, marijuana is predictably the first illicit drug most people encounter. Not surprisingly, most users of other illicit drugs have used marijuana first. In fact, most drug users begin with alcohol and nicotine before marijuana, usually before they are of legal age."

(Admissions to Treatment for Marijuana, 2009) According to the federal Treatment Episode Data Set, in 2009 there were 354,159 admissions to treatment with marijuana reported to be the primary substance of abuse, out of a total 1,963,089 admissions for all substances that year. According to the TEDS report:
"• Marijuana was reported as the primary substance of abuse by 18 percent of TEDS admissions aged 12 and older in 2009 [Table 1.1b].
"• The average age at admission for primary marijuana admissions was 24 years, although the peak age at admission for both sexes in all race/ethnicities was 15 to 17 years [Figure 12]. Forty percent of marijuana admissions were under age 20 (vs. 12 percent of all admissions), and primary marijuana abuse accounted for 70 percent of all admissions aged 12 to 14 years and 72 percent of admissions aged 15 to 17 years [Tables 2.1a-b].
"• Non-Hispanic Whites accounted for 48 percent of primary marijuana admissions (34 percent males and 14 percent females), and non-Hispanic Black males accounted for 23 percent [Table 2.3a].
"• Twenty-five percent of marijuana admissions had first used marijuana by age 12 and another 31 percent by age 14 [Table 2.5]."

(Admissions by Referral Source, 2009) "Primary marijuana admissions were less likely than all admissions combined to be self- or individually referred to treatment (15 percent vs. 33 percent)"
Federal statistics show that 56.2% of all primary marijuana admissions in 2009 were referred through criminal justice/DUI.

(Public Health Impact of Marijuana) "The public health burden of cannabis use is probably modest compared with that of alcohol, tobacco, and other illicit drugs. A recent Australian study⁹⁶ estimated that cannabis use caused 0·2% of total disease burden in Australia—a country with one of the highest reported rates of cannabis use. Cannabis accounted for 10% of the burden attributable to all illicit drugs (including heroin, cocaine, and amphetamines). It also accounted for around 10% of the proportion of disease burden attributed to alcohol (2·3%), but only 2·5% of that attributable to tobacco (7·8%)."

(Medical Cannabis Patients) "Analysis of the demographic and social characteristics of a large sample of applicants seeking approval to use marijuana medically in California supports an interpretation of long term non problematic use by many who had first tried it as adolescents, and then either continued to use it or later resumed its use as adults. In general, they have used it at modest levels and in consistent patterns which anecdotally-often assisted their educational achievement, employment performance, and establishment of a more stable life-style. These data suggest that rather than acting as a gateway to other drugs, (which many had also tried), cannabis has been exerting a beneficial influence on most."

"Tetrahydrocannabinol is a very safe drug. Laboratory animals (rats, mice, dogs, monkeys) can tolerate doses of up to 1,000 mg/kg (milligrams per kilogram). This would be equivalent to a 70 kg person swallowing 70 grams of the drug—about 5,000 times more than is required to produce a high. Despite the widespread illicit use of cannabis there are very few if any instances of people dying from an overdose. In Britain, official government statistics listed five deaths from cannabis in the period 1993-1995 but on closer examination these proved to have been deaths due to inhalation of vomit that could not be directly attributed to cannabis (House of Lords Report, 1998). By comparison with other commonly used recreational drugs these statistics are impressive."

An exhaustive search of the literature finds no deaths induced by marijuana. The US Drug Abuse Warning Network (DAWN) records instances of drug mentions in medical examiners' reports, and though marijuana is mentioned, it is usually in combination with alcohol or other drugs. Marijuana alone has not been shown to cause an overdose death.

(California Marijuana Arrestees) "In 1990, half of California’s marijuana possession arrestees were African-American, Latino, Asian, or other nonwhite and 35% were under age 20. In 2010, 64% were nonwhite and 52% were under age 20. Marijuana possession arrests of teenagers of color rose from 3,100 in 1990 to 16,400 in 2010 – an arrest surge 300% greater than population growth in that group."

(Risk of Arrest) "To provide a sense of the intensity of enforcement, we calculated the risk a marijuana user faces of being arrested for possession. If calculated per joint consumed, the figure nationally is trivial—perhaps one arrest for every 11,000–12,000 joints.⁴ However, the relevant risk may be the probability of being arrested during a year of normal consumption. Since marijuana is mostly consumed by individuals who use it at least once a month,⁵ we estimated the risk that such individuals face. We know from prior studies (e.g., Reuter, Hirschfield, and Davies, 2001) that these risks are higher for youth. Table 2.2 presents separate estimates for those aged 12–17 and for the entire population 12 and over. We observe that the annual risk of misdemeanor arrest for those 12–17 (6.6 percent) is more than twice the rate for the full population (3.0 percent)."

(State and Federal Marijuana Prisoners)

Total Federal Prisoners 2004 = 170,535
Total State Prisoners 2004 = 1,244,311

Percent of federal prisoners held for drug law violations = 55%
Percent of state prisoners held for drug law violations = 21%

Marijuana/hashish, Percent of federal drug offenders, 2004 = 12.4%
Marijuana/hashish, Percent of state drug offenders, 2004 = 12.7%

(Total prisoners x percent drug law) x percent marijuana = "marijuana prisoners"

Federal marijuana prisoners in 2004 = 11,630
State marijuana prisoners in 2004 = 33,186
Total federal and state marijuana prisoners in 2004 = 44,816

Note: These data only address people in prisons and thus exclude the 700,000+ offenders who may be in local jails because of a marijuana conviction.

(Marijuana Potency, UK) "Twenty-three Police Forces in England and Wales participated in the study [of cannabis potency]. In early 2008, they submitted 2,921 samples for analysis..." These are the conclusions:
"• The mean THC concentration (potency) of the sinsemilla samples was 16.2% (range = 4.1 to 46%). The median potency was 15.0%, close to values reported by others in the past few years.
"• The mean THC concentration (potency) of the traditional imported herbal cannabis samples was 8.4% (range = 0.3 to 22%); median = 9.0%. Only a very small number of samples were received and analysed.
"• The mean potency of cannabis resin was 5.9% (range = 1.3 to 27.8%). The median = 5.0% was typical of values reported by others over many years.
"• Cannabis resin had a mean CBD content of 3.5% (range = 0.1 to 7.3%), but the CBD content of herbal cannabis was less than 0.1% in nearly all cases."

(Primary Cultivation States) "California, Hawaii, Kentucky, Oregon, Tennessee, Washington, and West Virginia are the primary marijuana cultivation states (M7 states). Domestic Cannabis Eradication/Suppression Program (DCE/SP) data show that more than 8 million plants were eradicated in 2008, 89 percent (7,136,133 plants of 8,013,308 plants) of which were eradicated in the M7 States."

(Treatment Admissions for Marijuana) "... between these years [1992 and 2002] the rate of substance abuse treatment admissions reporting marijuana as their primary substance of abuse³ per 100,000 population increased 162 percent. Similarly, the proportion of marijuana admissions increased from 6 percent of all admissions in 1992 to 15 percent of all admissions reported to the Treatment Episode Data Set (TEDS) in 2002.
"During this time period, the percentage of marijuana treatment admissions that were referred from the criminal justice system increased from 48 percent of all marijuana admissions in 1992 to 58 percent of all marijuana admissions in 2002."

(Marijuana Potency) "Although marijuana grown in the United States was once considered inferior because of a low concentration of THC, advancements in plant selection and cultivation have resulted in higher THC-containing domestic marijuana. In 1974, the average THC content of illicit marijuana was less than one percent. Today most commercial grade marijuana from Mexico/Columbia and domestic outdoor cultivated marijuana has an average THC content of about 4 to 6 percent. Between 1998 and 2002, NIDA-sponsored Marijuana Potency Monitoring System (MPMP) analyzed 4,603 domestic samples. Of those samples, 379 tested over 15 percent THC, 69 samples tested between 20 and 25 percent THC and four samples tested over 25 percent THC."

(Sources of Marijuana) "Despite continuing increases in the amount of cannabis produced domestically, much of the marijuana available within the United States is foreign-produced. The two primary foreign source areas for marijuana distributed within the United States are Canada and Mexico. Mexican drug trafficking organizations (DTOs) have relocated many of their outdoor cannabis cultivation operations in Mexico from traditional growing areas to more remote locations in central and northern Mexico, primarily to reduce the risk of eradication and gain easier access to U.S. drug markets. Asian criminal groups are the primary producers of high-potency marijuana in Canada."

(Potency) "Statements in the popular media that the potency of cannabis has increased by ten times or more in recent decades are not support by the data from either the USA or Europe. As discussed in the body of this report, systematic data are not available in Europe on long-term trends and analytical and methodological issues complicate the interpretation of the information that is available. Data are stronger for medium and short-term trends where no major differences are apparent in Europe, although some modest increases are found in some countries. The greatest long-term changes in potency appear to have occurred in the USA. It should be noted here that before 1980 herbal cannabis potency in the USA was, according to the available data, very low by European standards."

(Potency) "There is growing evidence from this JRF [Joseph Rowntree Foundation] research and police seizure data that skunk, and home-grown herbal cannabis more generally, has become the most commonly used form of the drug among young people. This trend has been widely recognised by people in the drug field – and probably even better recognised by young people using cannabis. However, we have had no really reliable trend data with which to demonstrate this fundamental change in use. The growing fears over the past five years concerning the ‘new potency’ of cannabis have therefore been based largely on anecdote and conjecture."

(Potency) "Data on the THC content of cannabis products in the USA have been collected by ElSohly et al. (1984, 2000) for many years as part of the University of Mississippi Potency Monitoring Project. Samples were submitted by law enforcement agencies and it is assumed that they are representative of the market ... Although there has been an increase in potency of herbal cannabis over the twenty-five-year period, cannabis resin (and hash oil) showed no long term trends since 1980 when data were first collected. Although potency of sinsemilla showed clear upward trend in the final three years of the study, no such trend was obvious when the longer period of 1980-1995 is examined, particularly in view of the wide variations in potency that occurred from year to year (ElSohly et al., 2000). The THC content of herbal cannabis increased from around 1% before 1980 to around 4% in 1997. This increase, when seen in the European context, is deceptive. Before 1980, all herbal cannabis THC levels in the ElSohly study were less than 2.4%. By contrast, ... comparable levels at the time in the United Kingdom were twice as great. In other words, it must be assumed that the quality of herbal cannabis consumed in the USA more than twenty years ago was unusually poor, but that in recent years it has risen to levels typical of Europe. So even the modest increase found by ElSohly et al. (2000) may be less significant than it seems."

(Daily/Frequent Marijuana Use, 2011) "In 2011, an estimated 16.7 percent of past year marijuana users aged 12 or older used marijuana on 300 or more days within the past 12 months. This translates into nearly 5.0 million persons using marijuana on a daily or almost daily basis over a 12-month period.
"• In 2011, an estimated 39.1 percent (7.1 million) of current marijuana users aged 12 or older used marijuana on 20 or more days in the past month. This was similar to the 2010 estimate of 39.8 percent or 6.9 million users."

(NIDA Cannabis for Research, 1998) "Under the current contract with the University of Mississippi for any given year NIDA [National Institute on Drug Abuse] has the option to grow either 1.5 or 6.5 acres of cannabis, or to not grow any at all, depending on research demand. Generally, 1.5 acres are grown in alternate years. The number of cannabis cigarettes produced from 1.5 acres is about 50,000-60,000, although it can be higher. Cigarettes are produced in three potencies: strength 1 - 3-4 %; strength 2 - 1.8-2.2 %; and strength 3 - placebo, as close to 0% as possible. During the past three years, the following quantities have been shipped: 1994 - 24,000 cigarettes; 1995 - 23, 100 - cigarettes; and 1996 17,700 cigarettes. Virtually all of the cigarettes shipped in the last three years have been for single patient INDs. As of March 1997 there were 278, 100 cigarettes in stock. The cigarettes are maintained in frozen storage and have a useful life of approximately five years."

Physical and Psychological Effects

(Safety) "Tetrahydrocannabinol is a very safe drug. Laboratory animals (rats, mice, dogs, monkeys) can tolerate doses of up to 1000 mg/kg (milligrams per kilogram). This would be equivalent to a 70 kg person swallowing 70 grams of the drug —about 5,000 times more than is required to produce a high. Despite the widespread illicit use of cannabis there are very few if any instances of people dying from an overdose."

(Cognition) "In conclusion, our meta-analysis of studies that have attempted to address the question of longer term neurocognitive disturbance in moderate and heavy cannabis users has failed to demonstrate a substantial, systematic, and detrimental effect of cannabis use on neuropsychological performance. It was surprising to find such few and small effects given that most of the potential biases inherent in our analyses actually increased the likelihood of finding a cannabis effect."

(Cannabis and Memory) "Nevertheless, when considering all 15 studies (i.e., those that met both strict and more relaxed criteria) we only noted that regular cannabis users performed worse on memory tests, but that the magnitude of the effect was very small. The small magnitude of effect sizes from observations of chronic users of cannabis suggests that cannabis compounds, if found to have therapeutic value, should have a good margin of safety from a neurocognitive standpoint under the more limited conditions of exposure that would likely obtain in a medical setting."

(Lung Cancer) "These 19 diverse studies [analyzed by researchers in this article] offer biological evidence for the potential association between marijuana smoking and lung cancer. Most studies support an association between marijuana smoking and premalignant lung cancer findings, although small observational studies fail to demonstrate such an association."

"... Despite these findings, the small number of observational studies fail to demonstrate a clear association between marijuana smoking and diagnoses of lung cancer. Therefore, we must conclude that no convincing evidence exists for an association between marijuana smoking and lung cancer based on existing data."

(Head and Neck Squamous Cell Carcinoma) "We found that moderate marijuana use was significantly associated with reduced risk of HNSCC [head and neck squamous cell carcinoma]. This association was consistent across different measures of marijuana use (marijuana use status, duration, and frequency of use). Diminished risk of HNSCC did not differ across tumor sites, or by HPV [human papillomavirus] 16 antibody status. Further, we observed that marijuana use modified the interaction between alcohol and cigarette smoking, resulting in a decreased HNSCC risk among moderate smokers and light drinkers, and attenuated risk among the heaviest smokers and drinkers."

(Cancer Risk) "Nonetheless, and contrary to our expectations, we found no positive associations between marijuana use and lung or UAT cancers ... Despite several lines of evidence suggesting the biological plausibility of marijuana use being carcinogenic (1), it is possible that marijuana use does not increase cancer risk, as suggested in the recent commentary by Melamede."

(Cognition) "The results of our meta-analytic study failed to reveal a substantial, systematic effect of long-term, regular cannabis consumption on the neurocognitive functioning of users who were not acutely intoxicated. For six of the eight neurocognitive ability areas that were surveyed. the confidence intervals for the average effect sizes across studies overlapped zero in each instance, indicating that the effect size could not be distinguished from zero. The two exceptions were in the domains of learning and forgetting."

(Cognition) "Current marijuana use had a negative effect on global IQ score only in subjects who smoked 5 or more joints per week. A negative effect was not observed among subjects who had previously been heavy users but were no longer using the substance. We conclude that marijuana does not have a long-term negative impact on global intelligence. Whether the absence of a residual marijuana effect would also be evident in more specific cognitive domains such as memory and attention remains to be ascertained."

(Cognition) "Although the heavy current users experienced a decrease in IQ score, their scores were still above average at the young adult assessment (mean 105.1). If we had not assessed preteen IQ, these subjects would have appeared to be functioning normally. Only with knowledge of the change in IQ score does the negative impact of current heavy use become apparent."

(Cognition) "...our data suggest that over the long term cannabis use is not associated with greater declines in cognition among men, women, or heavy users ... these results would seem to provide strong evidence of the absence of a long term residual effect of cannabis use on cognition."
"We conclude that cognitive decline occurs across all age groups, with a significant proportion of persons of all ages showing declines near clinically significant levels after 12 years. Such decline is not associated with cannabis use in either men or women."

(Cannabis and Diabetes) "Our analyses of adults aged 20-59 years in the NHANES [National Health and Nutrition Examination Survey] III database showed that participants who used marijuana had lower prevalence of DM [Diabetes Mellitus] and had lower odds of DM relative to non-marijuana users. We did not find an association between the use of marijuana and other chronic diseases, such as hypertension, stroke, myocardial infarction and heart failure. This could be due to the smaller prevalence of stroke, myocardial infarction and heart failure in the examined age group.
"We noted the lowest prevalence of DM in current light marijuana users, with current heavy marijuana users and past users also having a lower prevalence of DM than non-marijuana users. The finding that past marijuana users had lower odds of prevalent DM than non-users suggests that early exposure to marijuana may affect the development of DM and a window of time of marijuana exposure earlier in life could be a factor to study. Similarly, our findings of a significant association between marijuana use and DM was only found in those aged $40 years suggest that the possibility of some protection from marijuana use may require many years before they become manifested. By contrast, it could reflect the increased prevalence of DM with age and the ability to detect an association with a lesser sample size when there is a greater cohort at risk for DM. The possible association of light marijuana use with decreased DM is similar to that of alcohol on DM and the metabolic syndrome, in which mild alcohol use was associated with lower prevalence of DM and the metabolic syndrome,^{14 15} and higher alcohol use associated with higher prevalence of DM and the metabolic syndrome.^{14 16}"

(Memory) "These results can be interpreted in several ways. A statistically reliable negative effect was observed in the domain of learning and forgetting, suggesting that chronic long-term cannabis use results in a selective memory defect. While the results are compatible with this conclusion, the effect size for both domains was of a very small magnitude. The "real life" impact of such a small and selective effect is questionable. In addition, it is important to note that most users across studies had histories of heavy longterm cannabis consumption. Therefore, these findings are not likely to generalize to more limited administration of cannabis compounds, as would be seen in a medical setting."

(Motivation) "The evidence for an "amotivational syndrome" among adults consists largely of case histories and observational reports (e.g. Kolansky and Moore, 1971; Millman and Sbriglio, 1986). The small number of controlled field and laboratory studies have not found compelling evidence for such a syndrome (Dornbush, 1974; Negrete, 1983; Hollister, 1986). ...it is doubtful that cannabis use produces a well defined amotivational syndrome."

(Psychosis) "This 10 year follow-up study showed that incident cannabis use significantly increased the risk of incident psychotic experiences. The association was independent of age, sex, socioeconomic status, use of other drugs, urban/rural environment, and childhood trauma; additional adjustment for other psychiatric diagnoses similarly did not change the results. There was no evidence for self medication effects as psychotic experiences did not predict later cannabis use. The results thus help to clarify the temporal association between cannabis use and psychotic experiences by systematically addressing the issue of reverse causality, given that the long follow-up period allowed exclusion of all individuals with pre-existing psychotic experiences or pre-existing cannabis use. In addition, cannabis use was confirmed as an environmental risk factor impacting on the risk of persistence of psychotic experiences (fig 3)."

(Psychosis) "... the expected rise in diagnoses of schizophrenia and psychoses did not occur over a 10 year period. This study does not therefore support the specific causal link between cannabis use and the incidence of psychotic disorders based on the 3 assumptions described in the Introduction. This concurs with other reports indicating that increases in population cannabis use have not been followed by increases in psychotic incidence (Macleod et al., 2006; Arsenault et al., 2004; Rey and Tennant, 2002)."

(Psychosis) "Although individual lifetime risk of chronic psychotic disorders such as schizophrenia, even in people who use cannabis regularly, is likely to be low (less than 3%), cannabis use can be expected to have a substantial effect on psychotic disorders at a population level because exposure to this drug is so common."

(Psychosis) "The lead researcher in the Christchurch study, Professor David Fergusson, said the role of cannabis in psychosis was not sufficient on its own to guide legislation. 'The result suggests heavy use can result in adverse side-effects,' he said. 'That can occur with ( heavy use of ) any substance. It can occur with milk.' Fergusson's research, released this month, concluded that heavy cannabis smokers were 1.5 times more likely to suffer symptoms of psychosis that non-users. The study was the latest in several reports based on a cohort of about 1000 people born in Christchurch over a four-month period in 1977. An effective way to deal with cannabis use would be to incrementally reduce penalties and carefully evaluate its impact, Fergusson said. 'Reduce the penalty, like a parking fine. You could then monitor ( the impact ) after five or six years. If it did not change, you might want to take another step.'

(Psychosis) "First, the use of cannabis and rates of psychotic symptoms were related to each other, independently of observed/non-observed fixed covariates and observed time dynamic factors (Table 2). Secondly, the results of structural equation modeling suggest that the direction of causation is that the use of cannabis leads to increases in levels of psychotic symptoms rather than psychotic symptoms increasing the use of cannabis. Indeed, there is a suggestion from the model results that increases in psychotic symptoms may inhibit the use of cannabis."

(Analgesic Effects) "The [endo] cannabinoids produce psychological states that closely parallel several experiences described as being related to the runner’s high. Compared with the opioid analgesics, the analgesia produced by the endocannabinoid system is more consistent with exercise induced analgesia. Activation of the endocannabinoid system also produces sedation, anxiolysis, a sense of wellbeing, reduced attentional capacity, impaired working memory ability, and difficulty in time estimation. This behavioural profile is similar to the psychological experiences reported by long distance runners."

(Safety) "There are health risks of cannabis use, most particularly when it is used daily over a period of years or decades. Considerable uncertainty remains about whether these effects are attributable to cannabis use alone, and about what the quantitative relationship is between frequency, quantity and duration of cannabis use and the risk of experiencing these effects.
"On existing patterns of use, cannabis poses a much less serious public health problem than is currently posed by alcohol and tobacco in Western societies."

(Safety) "A careful search of the literature and testimony of the nation's health officials has not revealed a single human fatality in the United States proven to have resulted solely from ingestion of marihuana. Experiments with the drug in monkeys demonstrated that the dose required for overdose death was enormous and for all practical purposes unachievable by humans smoking marihuana. This is in marked contrast to other substances in common use, most notably alcohol and barbiturate sleeping pills."

The World Health Organization reached the same conclusion in 1995.

(Safety) In 1988, the DEA's Administrative Law Judge, Francis Young, concluded: "In strict medical terms marijuana is far safer than many foods we commonly consume. For example, eating 10 raw potatoes can result in a toxic response. By comparison, it is physically impossible to eat enough marijuana to induce death. Marijuana in its natural form is one of the safest therapeutically active substances known to man. By any measure of rational analysis marijuana can be safely used within the supervised routine of medical care."

(Safety) "A review of the literature suggests that the majority of cannabis users, who use the drug occasionally rather than on a daily basis, will not suffer any lasting physical or mental harm. Conversely, as with other 'recreational' drugs, there will be some who suffer adverse consequences from their use of cannabis. Some individuals who have psychotic thought tendencies might risk precipitating psychotic illness. Those who consume large doses of the drug on a regular basis are likely to have lower educational achievement and lower income, and may suffer physical damage to the airways. They also run a significant risk of becoming dependent upon continuing use of the drug. There is little evidence, however, that these adverse effects persist after drug use stops or that any direct cause and effect relationships are involved."

(Cardiovascular Effects) Comparing marijuana, alcohol, nicotine and opiates, "The conclusion reached by the Institute of medicine in 1982 still stands: the smoking of marijuana 'causes changes to the heart and circulation that are characteristics of stress ...[but] there is no evidence ... that it exerts a permanently deleterious effect on the normal cardiovascular system ...'"

(Pulmonary Effects) "For physiological and pharmacological reasons,⁶¹ smoking cannabinoid herbals does not seem to have a similar health hazard profile as tobacco smoking, aside from the potential for bronchial irritation and bronchitis. Smoking cannabis was not associated with an increased risk of developing chronic obstructive pulmonary disease ..."

(Violence) "Laboratory studies also find no link between THC intoxication and violence. Most people who ingest THC before performing a competitive task in the laboratory do not show more aggression than people who receive placebos; occasionally they show decreased hostility. Numerous scientific panels sponsored by various governments invariably report that marijuana does not lead to violence.(751)"

(Withdrawal) "The withdrawal syndrome associated with dronabinol, the API [Active Pharmaceutical Ingredient] in Marinol®, produces symptoms in humans such as restlessness, irritability, mild agitation, anxiety, anger, insomnia, sleep EEG disturbances, nausea, decreased appetite, and decreased weight. Since a withdrawal syndrome is indicative of physical dependence, it is reasonable to conclude that generic dronabinol products (both naturally-derived [from the cannabis plant] or synthetically produced, and in hard or soft gelatin capsules) in sesame oil, will also produce physical dependence similar to those produced by Marinol®."

Note: "Dronabinol, the active ingredient in MARINOL® (dronabinol) Capsules, is synthetic delta-9-tetrahydrocannabinol (delta-9-THC). Delta-9-tetrahydrocannabinol is also a naturally occurring component of Cannabis sativa L. (Marijuana)." Sesame oil is an inactive ingredient of Marinol®.

(Withdrawal) "An abstinence syndrome has been reported after the abrupt discontinuation of dronabinol [Marinol®] in volunteers receiving dosages of 210 mg/day for 12 to 16 consecutive days. Within 12 hours after discontinuation, these volunteers manifested symptoms such as irritability, insomnia, and restlessness. By approximately 24 hours post-dronabinol discontinuation, withdrawal symptoms intensified to include “hot flashes”, sweating, rhinorrhea, loose stools, hiccoughs and anorexia.
"These withdrawal symptoms gradually dissipated over the next 48 hours. Electroencephalographic changes consistent with the effects of drug withdrawal (hyperexcitation) were recorded in patients after abrupt dechallenge. Patients also complained of disturbed sleep for several weeks after discontinuing therapy with high dosages of dronabinol."

(Liver Transplant Patients) "To prove their compliance with this policy, patients are subjected to blood and urine toxicology screening until [organ] transplantation. If a patient tests positive for a prohibited substance after signing this substance abuse policy, he or she will no longer be considered a candidate for liver transplantation at any center in Region 10.
"Substance abuse policies are necessary to help ensure that potential liver transplant recipients will be reliable stewards of the new organ. Despite this, concern exists that substance abuse policies may have an inappropriate and disproportionate impact on marijuana users. Firstly, many in the general public would argue that marijuana users should not have limited access to transplantation, particularly within the context of medical marijuana (6, 11). As an example, in May 2008, significant press coverage was given to the case of Timothy Garon, who reportedly died after having been refused a liver transplant, in part, because of his use of medical marijuana (12). Secondly, current toxicology screening methods produce a positive toxicology screen for cannabinoids up to two months after the patient’s last use (13). In contrast, other toxicology screening tests such as those for cocaine and alcohol become negative shortly after use. As a result, it may be more difficult for chronic marijuana users to demonstrate abstinence prior to life-ending decompensation of their liver disease."
=========
"Overall, the survival of marijuana users, as defined by this manuscript, with chronic liver disease who present for transplant evaluation is not significantly different from marijuana non-users."

(Alcohol v Marijuana - Displacement Effects) "Note that there is no evidence that the 13-year decline in marijuana use observed between 1979 and 1992 led to any accompanying increase in alcohol use, as many observers suggested would happen. In fact, through 1992 there was some parallel decline in annual, monthly, and daily alcohol use, as well as in occasions of heavy drinking among 12th graders. Earlier, when marijuana use rose in the late 1970s, alcohol use moved up along with it. As marijuana use rose again in the 1990s, alcohol use again rose with it, although certainly not as sharply. In sum, there has been little evidence from MTF over the years that supports what we have termed “the displacement hypothesis,” which asserts that an increase in marijuana use will somehow lead to a decline in alcohol use, or vice versa. Instead, both substances appear to move more in harmony, perhaps both reflecting changes in a more general construct, such as the tendency to use psychoactive substances, whether licit or illicit, or the frequency with which teens “party” or not. However, with alcohol use decreasing and marijuana use increasing over the past few years, it is possible that the displacement hypothesis is gaining support, highlighting the reality of historical change in types as well as causes of substance use. Our continued monitoring will provide the needed evidence about the displacement hypothesis in this current historical period."

Young People and Marijuana

(Vulnerability of Teens to Effects of Drugs) "The teen brain is a work in progress, making it more vulnerable than the mature brain to the physical effects of drugs. The potential for developing substance abuse and dependence is substantially greater when an individual’s first exposure to alcohol, nicotine and illicit drugs occurs during adolescence than in adulthood."

(Cognitive Deficit Among Adolescent-Onset Marijuana Users) "Our findings suggest that regular cannabis use before age 18 y predicts impairment, but others have found effects only for younger ages ^{(10, 15)}. Given that the brain undergoes dynamic changes from the onset of puberty through early adulthood ^{(37, 38)}, this developmental period should be the focus of future research on the age(s) at which harm occurs."

(Cognitive Decline Among Adolescent-Onset Marijuana Users) "In the present study, the most persistent adolescent-onset cannabis users evidenced an average 8-point IQ decline from childhood to adulthood. Quitting, however, may have beneficial effects, preventing additional impairment for adolescent-onset users. Prevention and policy efforts should focus on delivering to the public the message that cannabis use during adolescence can have harmful effects on neuropsychological functioning, delaying the onset of cannabis use at least until adulthood, and encouraging cessation of cannabis use particularly for those who began using cannabis in adolescence."

(Regular Adolescent Marijuana Use) "Results: Thematic analysis revealed that these [regular marijuana using] teens differentiated themselves from recreational users and positioned their use of marijuana for relief by emphasizing their inability to find other ways to deal with their health problems, the sophisticated ways in which they titrated their intake, and the benefits that they experienced. These teens used marijuana to gain relief from difficult feelings (including depression, anxiety and stress), sleep difficulties, problems with concentration and physical pain. Most were not overly concerned about the risks associated with using marijuana, maintaining that their use of marijuana was not 'in excess' and that their use fit into the realm of 'normal.'

"Conclusion: Marijuana is perceived by some teens to be the only available alternative for teens experiencing difficult health problems when medical treatments have failed or when they lack access to appropriate health care."

(Adolescent Motivation) "The apparent strength of these relationships in cross-sectional studies (e.g. Kandel, 1984) has been exaggerated because those adolescents who are most likely to use cannabis have lower academic aspirations and poorer high school performance prior to using cannabis than their peers who do not (Newcombe and Bentler, 1988). It remains possible that factors other than the marijuana use account for apparent causal relations. To the extent they may exist, these adverse effects of cannabis and other drug use upon development over and above the effect of pre-existing nonconformity may cascade throughout young adult life, affecting choice of occupation, level of income, choice of mate, and the quality of life of the user and his or her children."

(Cannabis Smoking and Pulmonary Function) "In this 20-year study of marijuana and pulmonary function, we confirmed the expected reductions in FEV1 [Forced expiratory volume in the first second of expiration] and FVC [forced vital capacity] from tobacco use. In contrast, marijuana use was associated with higher FEV1 and FVC at the low levels of exposure typical for most marijuana users. With up to 7 joint-years of lifetime exposure (eg, 1 joint/d for 7 years or 1 joint/wk for 49 years), we found no evidence that increasing exposure to marijuana adversely affects pulmonary function. This association, however, was nonlinear: at higher exposure levels, we found a leveling off or even a reversal in this association, especially for FEV1. Although our sample contained insufficient numbers of heavy users to confirm a detrimental effect of very heavy marijuana use on pulmonary function, our findings suggest this possibility."

(Early Use of Marijuana) "The younger and more often teens use marijuana, the more likely they are to engage in other substance use and the higher their risk of developing a substance use disorder. Among high school students, 7.5 percent used marijuana for the first time before the age of 13. CASA’s analysis of national data finds that the average age of initiation of marijuana use among high school students is 14.3 years old. Compared to those who began using marijuana after age 21, those who first used it before age 15 are:
• More likely to have ever smoked a cigarette (93.3 percent vs. 86.4 percent);
• More than twice as likely to have ever misused controlled prescription drugs (56.5 percent vs. 22.9 percent); and
• Two and a half times as likely to have ever used other illicit drugs (70.2 percent vs. 27.8 percent)."

(Prevalence and Perceived Risk of Marijuana Use) "Marijuana use, which had been rising among teens for the past four years, continued to rise in 2011 in all prevalence periods for 10th and 12th graders; but in 2012 these increases halted. The recent rise in use stood in stark contrast to the long, gradual decline that had been occurring over the preceding decade. (Although use among 8th graders had been rising, annual prevalence decreased after 2010.) It is relevant that perceived risk for marijuana has been falling for the past six years, and disapproval declined for the past three to four years. These changes would normally portend a further increase in use."

(Marijuana Use vs. Tobacco Use) "High school students are more likely to use marijuana than to smoke cigarettes. High school students are:
"• More likely to have tried marijuana than tobacco (24 percent vs. 15 percent); and
"• More likely to say their close friends use marijuana than smoke cigarettes (51 percent vs. 39 percent)."

(Marijuana Use by Peers and Perception of Harm) "Teens also say they are seeing more peers in school smoking marijuana and more teens (73 percent) report having friends who smoke marijuana regularly (71 percent) – significantly higher than four years ago. Since 2008, there have also been significant declines in teen perceptions that they will lose respect, harm themselves, or mess up their lives if they use marijuana."

(12th Graders and Attitudes Toward Legalizing Marijuana) "Despite the fact that many 12th graders in 2011 reported ever having used marijuana themselves (46%), and many do not judge it to be as dangerous as other drugs, nearly two-thirds (64%) favor legally prohibiting marijuana use in public places. Only about one-third (34%) favor prohibiting marijuana use in private, however."
^{Note: Only 34% of 12th graders favored prohibiting marijuana use in private, and 39.2% agreed that using marijuana should be entirely legal.}

Cannabis and Driving

(Thresholds for Serum THC Level Compared With Blood Alcohol Content) "Risk thresholds could be formulated only for THC which was the most prevalent illicit drug in the general driving population and in injured/killed drivers. The prevalence of THC across all countries that participated in DRUID is 1.37%. This is about one third of the alcohol prevalence. The epidemiological, the experimental and the meta-analytical approaches result in rather low risk estimations. Epidemiological case-control studies assess at maximum a 2.4-fold risk for injury, experimental studies and meta-analysis rank the risk between 0.5 and 2 times than that of sober driving. So THC seems to be much less impairing and risky than most of the other examined substances. Although a relationship between THC concentration and accident risk was found in the epidemiological studies, it was only possible to set an exact THC cut-off by a meta-analysis of experimental studies. Thereby it was found that the serum concentration of 3.8ng/mL THC (≈2ng/mL in whole blood) causes the same amount of impairment as 0.5g/L alcohol. This value could be an empirical basis for a threshold discussion. The meta-analysis could also be used to define limits comparable to lower BAC levels."

(Marijuana, Alcohol, and Driving) "As with cannabis, alcohol use increased variability in lane position and headway (Casswell, 1979; Ramaekers et al., 2000; Smiley et al., 1981; Stein et al., 1983) but caused faster speeds (Casswell, 1977; Krueger & Vollrath, 2000; Peck et al., 1986; Smiley et al., 1987; Stein et al., 1983). Some studies also showed that alcohol use alone and in combination with cannabis affected visual search behavior (Lamers & Ramaekers, 2001; Moskowitz, Ziedman, & Sharma, 1976). Alcohol consumption combined with cannabis use also worsened driver performance relative to use of either substance alone. Lane position and headway variability were more exaggerated (Attwood et al., 1981; Ramaekers et al., 2000; Robbe, 1998) and speeds were faster (Peck et al., 1986).
"Both simulator and road studies showed that relative to alcohol use alone, participants who used cannabis alone or in combination with alcohol were more aware of their intoxication. Robbe (1998) found that participants who consumed 100 g/kg of cannabis rated their performance worse and the amount of effort required greater compared to those who consumed alcohol (0.05 BAC). Ramaekers et al. (2000) showed that cannabis use alone and in combination with alcohol consumption increased self-ratings of intoxication and decreased self-ratings of performance. Lamers and Ramaekers (2001) found that cannabis use alone (100 g/kg) and in combination with alcohol consumption resulted in lower ratings of alertness, greater perceptions of effort, and worse ratings of performance."

(Accident Risk) "Our primary analysis looked at the risk of a motor vehicle collision while under the influence of cannabis and included all nine studies (relating to 49 411 participants). The pooled risk of a motor vehicle collision while driving under the influence of cannabis was almost twice the risk while driving unimpaired (odds ratio 1.92 (95% confidence interval 1.35 to 2.73); P=0.0003); we noted heterogeneity among the individual study effects (I2=81%).
"We also assessed culpability and non-culpability studies separately and explored differences between motor vehicle collisions resulting in deaths and non-fatal injuries. Meta-analyses on subgroups of studies explored the potential effect of specific features related to study design and potential biases: case-control studies versus culpability studies, fatal collisions versus non-fatal collisions, and high quality studies versus medium quality studies (fig 3⇓).
"High quality studies had a pooled odds ratio that was higher than that for medium quality studies, although both results showed a significant association at the 0.05 level. Furthermore, case-control studies (2.79 (1.23 to 6.33); P=0.01) estimated the effect of cannabis use on crash risk to be higher than that estimated by culpability studies (1.65 (1.11 to 2.46); P=0.07). Studies of fatal collisions (2.10 (1.31 to 3.36); P=0.002) had a pooled odds ratio that was statistically significant, but studies of non-fatal collisions (1.74 (0.88 to 3.46); P=0.11) did not show significant results.
"In all studies assessing cannabis use in conjunction with alcohol, the estimated odds ratio for cannabis and alcohol combined was higher than for cannabis use alone, suggesting the presence of a synergistic effect."

(Smartphone Use) "Although for the mobile phone conversation and cannabis studies the reaction times were slightly different, they were still comparable. The same visual stimulus was used and was presented in the same visual scene. When reaction times under each condition were compared with the baseline reaction times measured, alcohol gave a 12.5% increase in reaction times, cannabis a 21% increase, a hands-free mobile phone conversation increased reaction times by 26.5%, texting by 37.4%, using a smartphone for social networking by 37.6% and using a mobile phone for a hand-held mobile phone conversation increased reaction times by 45.9% compared to the baseline condition. Thus, using a smartphone for social networking resulted in a greater impairment to reaction times than alcohol, cannabis, hand held mobile phone conversations and texting, but less than a hand held mobile conversation."

(Times for THC Absorption, Bioavailability, and Excretion) "Absorption is slower following the oral route of administration with lower, more delayed peak THC levels. Bioavailability is reduced following oral ingestion due to extensive first pass metabolism. Smoking marijuana results in rapid absorption with peak THC plasma concentrations occurring prior to the end of smoking. Concentrations vary depending on the potency of marijuana and the manner in which the drug is smoked, however, peak plasma concentrations of 100-200 ng/mL are routinely encountered. Plasma THC concentrations generally fall below 5 ng/mL less than 3 hours after smoking. THC is highly lipid soluble, and plasma and urinary elimination half-lives are best estimated at 3-4 days, where the rate-limiting step is the slow redistribution to plasma of THC sequestered in the tissues. Shorter half-lives are generally reported due to limited collection intervals and less sensitive analytical methods. Plasma THC concentrations in occasional users rapidly fall below limits of quantitation within 8 to 12 h."

(Accident Risk) "We found only limited evidence to support the claim that cannabis use increases accident risk. Participants who had driven under the influence of cannabis in the previous year appeared to be no more likely than drug-free drivers to report that they had had an accident in the previous 12 months. Prima facie, this would seem to suggest that cannabis-intoxicated driving is not a risk factor for non-fatal accidents. In this sense, the results would support those of Longo et al. (2000b) who found no relationship between recent cannabis use and driver culpability for non-fatal accidents."

(THC and Cannabis Dosages) "THC is the major psychoactive constituent of cannabis. Potency is dependent on THC concentration and is usually expressed as %THC per dry weight of material. Average THC concentration in marijuana is 1-5%, hashish 5-15%, and hashish oil ≥ 20%. The form of marijuana known as sinsemilla is derived from the unpollinated female cannabis plant and is preferred for its high THC content (up to 17% THC). Recreational doses are highly variable and users often titer their own dose. A single intake of smoke from a pipe or joint is called a hit (approximately 1/20th of a gram). The lower the potency or THC content the more hits are needed to achieve the desired effects; 1-3 hits of high potency sinsemilla is typically enough to produce the desired effects. In terms of its psychoactive effect, a drop or two of hash oil on a cigarette is equal to a single “joint” of marijuana. Medicinally, the initial starting dose of Marinol® is 2.5 mg, twice daily."

(Accident Risk) "Cannabis use impairs cognitive, memory and psycho-motor performance in ways that may impair driving.¹⁰ Recent data suggest that approximately 5% of Canadian drivers/adults report driving after cannabis use in the past year.³⁹ Large-scale epidemiological studies using different methodologies (e.g., retrospective epidemiological and case control studies) have found that cannabis use acutely increases the risk of motor vehicle accident (MVA) involvement and fatal crashes among drivers.^40,41 Recent reviews have found the increase in risk to be approximately 1.5-3.0, an increase which is substantially lower, however, than that in alcohol-impaired drivers. The impairment from concurrent alcohol and cannabis use may be multiplicative, so individuals who drive under the influence of both drugs may be at higher risk for MVAs.⁴² An expert consensus view was that a THC concentration of 7-10 nanograms per millilitre in serum would produce impairment equivalent to that of 0.05% blood alcohol content (BAC). It was suggested that this level could serve as a 'per se' limit to define cannabis-impaired driving.⁴³ Current research suggests that acute impairment from cannabis typically clears 3-4 hours after use.⁴⁴
"This time span could be recommended to users as a minimum wait period before driving. The required wait before driving would need to be longer for higher doses, and would also vary on the basis of individual variation."

(Accident Risk) "A review of over a dozen of these [laboratory] experiments reveals three findings. First, after using marijuana, people drive more slowly. In addition, they increase the distance between their cars and the car in front of them. Third, they are less likely to attempt to pass other vehicles on the road. All of these practices can decrease the chance of crashes and certainly limit the probability of injury or death if an accident does occur. These three habits may explain the slightly lower risk of accidents that appears in the epidemiological studies. These results contrast dramatically to those found for alcohol. Alcohol intoxication often increases speed and passing while decreasing following distance, and markedly raises the chance of crashes.(632)"

(Impairment) "There is considerable evidence from laboratory studies that cannabis (marijuana) impairs reaction time, attention, tracking, hand-eye coordination, and concentration, although not all of these impairments were equally detected by all studies (Couper & Logan, 2004a; Heishman, Stitzer, & Yingling, 1989; Gieringer, 1988; Moskowitz, 1985). In reviewing the literature on marijuana, Smiley (1998) concluded that marijuana impairs performance in divided attention tasks (i.e., a poorer performance on subsidiary tasks). Jones et al. (2003) adds that Smiley’s finding is relevant to the multitasking essence of driving, in particular by making marijuana impaired drivers perhaps less able to handle unexpected events. Interestingly, there is also evidence showing that, unlike alcohol, marijuana enhances rather than mitigates the individual’s perception of impairment (Lamers & Ramaekers, 1999; Robbe & O'Hanlon, 1993; Perez-Reyes, Hicks, Bumberry, Jeffcoat, & Cook, 1988). Robbe and O'Hanlon (1993) reported that in laboratory conditions, drivers under the influence of marijuana were aware of their impairment, which led them to decrease speed, avoid passing other vehicles, and reduce other risk-taking behaviors. Such was not the case with alcohol; for the authors reported that alcohol-impaired drivers were generally not aware of impairment, and therefore did not adjust their driving accordingly."

(Driving After Consumption) "Cannabis is only considered a risk factor for traffic accidents if drivers operate vehicles after consuming the drug. Robbe (1994) found that 30% to 90% of his participants were willing to drive after consuming a typical dose of cannabis. This is consistent with a recent Australian survey in which more than 50% of users drove after consuming cannabis (Lenne, Fry, Dietze, & Rumbold, 2000). A self administered questionnaire given to 508 students in grades 10 to 13 in Ontario, Canada, found that 19.7% reported driving within an hour after using cannabis (Adlaf, Mann, & Paglia, 2003)."

(Impairment) "Participants receiving active marijuana decreased their speed more so than those receiving the placebo cigarette during a distracted section of the drive, An overall effect of marijuana was seen for the mean speed during the distracted driving (PASAT [Paced Auditory Serial-Addition Test] section), While no other changes in driving performance were found, marijuana appeared to hinder practice effects on the PASAT task, suggesting individuals may not be able to adequately use information and experience previously acquired while under the influence of marijuana, While only minimal differences in driving performance were found, this failure to benefit from prior practice may be detrimental to driving performance. Research has shown that graduated driver's licensing programs in which participants receive more on the road training results in a decrease in fatal crashes in 16-year-olds (Baker, Chen & Li 2006), If marijuana indeed impairs one's ability to use prior experience to improve performance, this will likely impair driving under pretrained conditions (e,g,, steering into a skid, allowing increased stopping time on slippery roads, etc)."

(Impairment) "The present study's subtle finding of decreased speed under the influence of acute marijuana is generally consistent with the literature, which has found that marijuana's effects on driving can be subtle. In Berghaus's review of the literature prior to 1995, 45% of driving simulator studies showed no impairment from marijuana within the first hour after use (Berghaus, Scheer & Schmidt 1995), More cautious driving behaviors were found in several studies (Lamers & Ramaekers 2001; Stein et al, 1983; Ellingstad, McFarling & Struckman 1973; Rafaelsen, Bech & Rafaelsen 1973; Dott 1972), while an increased reaction time for stopping was the most common finding (Liguori, Gatto & Robinson 1998; Rafaelsen, Bech & Rafaelsen 1973), Moskowitz, Ziedman and Sharma (1976) also found slowed reaction times for a visual choice-reaction time task administered while driving and Smiley, Moskowitz and Zeidman (1981) found increased variability in velocity and lateral position while following curves and while controlling the car in gusts of wind with a high dose of marijuana (200 mcg/kg THC) but not with a lower dose (100 mcg/kg THC), They also found an increase in variability of headway and lateral position while following other cars."

(More Data Needed) "The decreased speed during the simulated drive could be interpreted as an attempt to compensate for perceived cognitive impairment, Alternatively, marijuana may not have affected decision making and judgment and the reduction in speed would improve safety margins, While the clinical significance of a 3% to 5% decrease in speed may be questioned, previous research suggests such a decrease will result in approximately a 7% decrease in all injuries and a 15% decrease in fatalities (Nilsson 1981), Use of an alternate task design in which subjects are requested to drive as quickly and as safely as possible rather than following a posted speed limit may provide more insight into compensatory strategies employed while driving under the influence of marijuana, Use of a more challenging road paradigm (e.g., icy or gravel roads) which capitalizes on the use of practice effects may aid in identifying differences in driving performance under the influence of marijuana, There was significant between-subject variability in driving measures and future studies would be further strengthened by using a within-subjects design."

(Driving) "Epidemiological studies have been inconclusive regarding whether cannabis use causes an increased risk of motor vehicle accidents; in contrast, unanimity exists that alcohol use increases crash risk.³⁰ In tests using driving simulation, neurocognitive impairment varies in a dose-related fashion, and symptoms are more pronounced with highly automatic driving functions than with more complex tasks that require conscious control.³¹ Cannabis smokers tend to over-estimate their impairment and compensate effectively while driving by utilizing a variety of behavioral strategies."

(Marijuana, Alcohol, and Driving) "When compared to alcohol, cannabis is detected far less often in accident-involved drivers. Drummer et al. (2003) cited several studies and found that alcohol was detected in 12.5% to 79% of drivers involved in accidents. With regard to crash risk, a large study conducted by Borkenstein, Crowther, Shumate, Zeil and Zylman (1964) compared BAC in approximately 6,000 accident-involved drivers and 7,600 nonaccident controls. They determined the crash risk for each BAC by comparing the number of accident-involved drivers with detected levels of alcohol at each BAC to the number of nonaccident control drivers with the same BAC. They found that crash risk increased sharply as BAC increased. More specifically, at a BAC of 0.10, drivers were approximately five times more likely to be involved in an accident.
"Similar crash risk results were obtained when data for culpable drivers were evaluated. Drummer (1995) found that drivers with detected levels of alcohol were 7.6 times more likely to be culpable. Longo et al. (2000) showed that drivers who tested positive for alcohol were 8.0 times more culpable, and alcohol consumption in combination with cannabis use produced an odds ratio of 5.4. Similar results were also noted by Swann (2000) and Drummer et al. (2003)."

(Driving and THC Levels) "Most of the research on cannabis use has been conducted under laboratory conditions. The literature reviews by Robbe (1994), Hall, Solowij, and Lemon (1994), Border and Norton (1996), and Solowij (1998) agreed that the most extensive effect of cannabis is to impair memory and attention. Additional deficits include problems with temporal processing, (complex) reaction times, and dynamic tracking. These conclusions are generally consistent with the psychopharmacological effects of cannabis mentioned above, including problems with attention, memory, motor coordination, and alertness.
"A meta-analysis by Krüger and Berghaus (1995) profiled the effects of cannabis and alcohol. They reviewed 197 published studies of alcohol and 60 studies of cannabis. Their analysis showed that 50% of the reported effects were significant at a BAC of 0.073 g/dl and a THC level of 11 ng/ml. This implies that if the legal BAC threshold for alcohol is 0.08 g/dl, the corresponding level of THC that would impair the same percentage of tests would be approximately 11 ng/ml."

(Driving Performance) "Several studies have examined cannabis use in driving simulator and on-road situations. The most comprehensive review was done by Smiley in 1986 and then again in 1999. Several trends are evident and can be described by three general performance characteristics:
"1. Cannabis increased variability of speed and headway as well as lane position (Attwood, Williams, McBurney, & Frecker, 1981; Ramaekers, Robbe, & O'Hanlon, 2000; Robbe, 1998; Sexton et al., 2000; Smiley, Moskowitz, & Zeidman, 1981; Smiley, Noy, & Tostowaryk, 1987). This was more pronounced under high workload and unexpected conditions, such as curves and wind gusts.
"2. Cannabis increased the time needed to overtake another vehicle (Dott, 1972 [as cited in Smiley, 1986]) and delayed responses to both secondary and tracking tasks (Casswell, 1977; Moskowitz, Hulbert, & McGlothlin,
1976; Sexton et al., 2000; Smiley et al., 1981).
"3. Cannabis resulted in fewer attempts to overtake another vehicle(Dott, 1972) and larger distances required to pass (Ellingstad et al., 1973 [as cited in Smiley, 1986]). Evidence of increased caution also included slower speeds (Casswell, 1977; Hansteen, Miller, Lonero, Reid, & Jones, 1976; Krueger & Vollrath, 2000; Peck, Biasotti, Boland, Mallory, & Reeve, 1986; Sexton et al., 2000; Smiley et al., 1981; Stein, Allen, Cook, & Karl, 1983) and larger headways (Robbe, 1998; Smiley et al., 1987)."

(Driving Behavioral Compensation) "Both Australian studies suggest cannabis may actually reduce the responsibility rate and lower crash risk. Put another way, cannabis consumption either increases driving ability or, more likely, drivers who use cannabis make adjustments in driving style to compensate for any loss of skill (Drummer, 1995). This is consistent with simulator and road studies that show drivers who consumed cannabis slowed down and drove more cautiously (see Ward & Dye, 1999; Smiley, 1999. This compensation could help reduce the probability of being at fault in a motor vehicle accident since drivers have more time to respond and avoid a collision. However, it must be noted that any behavioral compensation may not be sufficient to cope with the reduced safety margin resulting from the impairment of driver functioning and capacity."

(Cannabis Substitution Effects) "Another paradigm used to assess crash risk is to use cross-sectional surveys of reported nonfatal accidents that can be related to the presence of risk factors, such as alcohol and cannabis consumption. Such a methodology was employed in a provocative dissertation by Laixuthai (1994). This study used data from two large surveys that were nationally representative of high school students in the United States during 1982 and 1989. Results showed that cannabis use was negatively correlated with nonfatal accidents, but these results can be attributed to changes in the amount of alcohol consumed. More specifically, the decriminalization of cannabis and the subsequent reduction in penalty cost, as well as a reduced purchase price of cannabis, made cannabis more appealing and affordable for young consumers. This resulted in more cannabis use, which substituted for alcohol consumption, leading to less frequent and less heavy drinking. The reduction in the amount of alcohol consumed resulted in fewer nonfatal accidents."

(Intoxication Self-Ratings) "Both simulator and road studies showed that relative to alcohol use alone, participants who used cannabis alone or in combination with alcohol were more aware of their intoxication. Robbe (1998) found that participants who consumed 100 g/kg of cannabis rated their performance worse and the amount of effort required greater compared to those who consumed alcohol (0.05 BAC). Ramaekers et al. (2000) showed that cannabis use alone and in combination with alcohol consumption increased self-ratings of intoxication and decreased self-ratings of performance. Lamers and Ramaekers (2001) found that cannabis use alone (100 g/kg) and in combination with alcohol consumption resulted in lower ratings of alertness, greater perceptions of effort, and worse ratings of performance."

(Mediation of Impairment) "In conclusion, cannabis impairs driving behaviour. However, this impairment is mediated in that subjects under cannabis treatment appear to perceive that they are indeed impaired. Where they can compensate, they do, for example, by not overtaking, by slowing down and by focusing their attention when they know a response will be required. However, such compensation is not possible where events are unexpected or where continuous attention is required. Effects of driving behaviour are present up to an hour after smoking but do not continue for extended periods."
"Thus, not only is it problematic to estimate the percentage of accident involvements associated with cannabis use alone, there is no evidence that impairment resulting from cannabis use causes accidents. Attempts to alleviate these problems by calculating risk of culpability for an accident (rather than the risk of having an accident) suggest that cannabis may actually reduce responsibility for accidents."

On November 6, 2012, a majority of the voters in the states of Colorado and Washington voted in favor of ballot measures which legalized the adult social use of marijuana.

Marijuana - Law and Policy

The U.S. Penal Code violations for marijuana and possible sentences:
Violation: "1000 kilograms or more of a mixture or substance containing a detectable amount of marihuana, or 1,000 or more marihuana plants regardless of weight."
Sentence: not "less than 10 years or more than life" "No person sentenced under this subparagraph shall be eligible for parole during the term of imprisonment imposed therein."

Violation: "100 kilograms or more of a mixture or substance containing a detectable amount of marihuana, or 100 or more marihuana plants regardless of weight."
Sentence: not "less than 5 years and not more than 40 years" "No person sentenced under this subparagraph shall be eligible for parole during the term of imprisonment imposed therein."

Violation: "less than 50 kilograms of marihuana, except in the case of 50 or more marihuana plants regardless of weight, 10 kilograms of hashish, or one kilogram of hashish oil"
Sentence: "not more than 5 years, a fine not to exceed the greater of that authorized in accordance with the provisions of title 18 or $250,000 if the defendant is an individual or $1,000,000 if the defendant is other than an individual, or both."

"Based on the research to date, the harms associated with the actual use of cannabis likely pale in comparison with the widely observed harms attributable to cannabis prohibition. As such, policymakers should integrate the scientific research conducted on the likely impacts of current prohibitive approaches to cannabis use into the process of optimising cannabis policy."

(Canada)
"RECOMMENDATIONS
"1. The severity of punishment for a cannabis possession charge should be reduced. Specifically, cannabis possession should be converted to a civil violation under the Contraventions Act.
"The current law involves considerable enforcement and other criminal justice costs, as well as adverse consequences to individual drug offenders, with little evidence of a substantial deterrent impact on cannabis use, and at best marginal benefits to the public health and safety of Canadians. As a minimal measure, jail should be removed as a sentencing option for cannabis possession. The available evidence indicates that removal of jail as a sentencing option would lead to considerable cost savings without leading to increases in rates of cannabis use. Punishing cannabis possession with a fine only would be consistent with current practices and prevailing public opinion."

(The Netherlands and Depenalization of Cannabis Use) "There is no evidence that the depenalization component of the 1976 policy, per se, increased levels of cannabis use. On the other hand, the later growth in commercial access to cannabis, after de facto legalization, was accompanied by steep increases in use, even among youth. In interpreting that association, three points deserve emphasis. First, the association may not be causal; we have already seen that recent increases occurred in the United States and Oslo despite very different policies. Second, throughout most of the first two decades of the 1976 policy, Dutch use levels have remained at or below those in the United States. And third, it remains to be seen whether prevalence levels will drop again in response to the reduction to a 5-g limit, and to recent government efforts to close down coffee shops and more aggressively enforce the regulations."

(Real Risk of Arrest) "It is also important to point out that in no Western country is a user at much risk of being criminally penalized for using marijuana. The rates of arrest for past-year marijuana users in Western countries are typically less than or equal to 3 percent (Kilmer, 2002; Room et al., 2010). More important, almost none of those convicted of simple possession is incarcerated or receives a fine exceeding $1,000 (Pacula, MacCoun, et al., 2005)."

(Use Rates and Decriminalization) "In California and Ohio, surveys before and after decriminalisation showed that cannabis use increased, but not at a greater rate than in US states which had not decriminalised cannabis. Single (1989) also reviewed data from two large US national surveys of drug use in the 1970s that compared rates of cannabis use in states which had and had not decriminalised cannabis. He found that the prevalence of cannabis use increased in all states, with a larger increase in those states which had not decriminalised (Single, 1989)."

(Recommendation by the Canadian Senate's Special Committee on Illegal Drugs) "... the Government of Canada amend the Controlled Drugs and Substances Act to create a criminal exemption scheme. This legislation should stipulate the conditions for obtaining licenses as well as for producing and selling cannabis; criminal penalties for illegal trafficking and export; and the preservation of criminal penalties for all activities falling outside the scope of the exemption scheme."

(UK Police Foundation) "Our conclusion is that the present law on cannabis produces more harm than it prevents. It is very expensive of the time and resources of the criminal justice system and especially of the police. It inevitably bears more heavily on young people in the streets of inner cities, who are also more likely to be from minority ethnic communities, and as such is inimical to police-community relations. It criminalizes large numbers of otherwise law-abiding, mainly young, people to the detriment of their futures. It has become a proxy for the control of public order; and it inhibits accurate education about the relative risks of different drugs including the risks of cannabis itself."

Sociopolitical Research

(1972 National Commission on Marihuana and Drug Abuse) "Rather than inducing violent or aggressive behavior through its purported effects of lowering inhibitions, weakening impulse control and heightening aggressive tendencies, marihuana was usually found to inhibit the expression of aggressive impulses by pacifying the user, interfering with muscular coordination, reducing psychomotor activities and generally producing states of drowsiness lethargy, timidity and passivity."

(1972 National Commission on Marihuana and Drug Abuse) "Marihuana's relative potential for harm to the vast majority of individual users and its actual impact on society does not justify a social policy designed to seek out and firmly punish those who use it. This judgment is based on prevalent use patterns, on behavior exhibited by the vast majority of users and on our interpretations of existing medical and scientific data. This position also is consistent with the estimate by law enforcement personnel that the elimination of use is unattainable."

(Decriminalization and Prevalence of Use) "Proponents of criminalization attribute to their preferred drug-control regime a special power to affect user behavior. Our findings cast doubt on such attributions. Despite widespread lawful availability of cannabis in Amsterdam, there were no differences between the 2 cities [Amsterdam and San Francisco] in age at onset of use, age at first regular use, or age at the start of maximum use."
"Our findings do not support claims that criminalization reduces cannabis use and that decriminalization increases cannabis use."

(Decriminalization and Use) "... our results indicate that the increase in participation was due to individuals over 30 delaying giving up cannabis use as a result of its changed legal status, not an increase in use by younger people. This finding provides an explanation of why US studies based on youth fail to find that decriminalization has an impact on the probability of cannabis use, while studies based on adults and youth, or just adults, do find a positive association between decriminalization and participation in cannabis use."

(Cannabis Substitution Treatment) "Only orally given THC and, to a lesser extent, nefazodone have shown promise [in treating marijuana dependence]. THC reduced craving and ratings of anxiety, feelings of misery, difficulty sleeping, and chills (Haney et al., 2004). In addition, participants could not distinguish active THC from placebo. These findings were replicated in an outpatient study, which found that a moderate oral dosage of THC (10 mg, three times daily) suppressed many marijuana withdrawal symptoms and that a higher dosage (30 mg, three times daily) almost completely abolished withdrawal symptoms (Budney et al., 2007)."

(Decriminalization and Use Rates) "The available evidence suggests that removal of the prohibition against possession itself (decriminalization) does not increase cannabis use. In addition to the Dutch experience from 1976 to 1983, we have similar findings from analysis of weaker decriminalization (with fines retained for the offense of simple possession of small quantities) in 12 US states (Single, 1989) and South Australia and the Australian Capital Territory (Hall, 1997; McGeorge & Aitken, 1997). The fact that Italy and Spain, which have decriminalized possession for all psychoactive drugs, have marijuana use rates comparable to those of neighboring countries provides further support."

Synthetic Cannabinoids

"Synthetic cannabinoids are substances chemically produced to mimic tetrahydrocannabinol (THC), the active ingredient in marijuana. When these substances are sprayed onto dried herbs and then consumed through smoking or oral ingestion, they can produce psychoactive effects similar to those of marijuana."

"Synthetic cannabinoids are functionally similar to delta9-tetrahydrocannabinol (THC), the psychoactive principle of cannabis, and bind to the same cannabinoid receptors in the brain and peripheral organs."

(Spice Use Among 12 Graders) "Synthetic marijuana, which goes by such names as Spice and K-2, is an herbal drug mixture that usually contains designer chemicals that fall into the cannibinoid family. Until March of 2011 these drugs were not scheduled by the Drug Enforcement Administration, so they were readily available on the internet and in head shops, gas stations, etc. The DEA did schedule them under its emergency authority for one year, beginning March 1, 2011, making their possession and sale no longer legal. MTF first addressed the use of synthetic marijuana in its 2011 survey, asking 12th graders about use in the prior 12 months, which would have covered a considerable period of time prior to the drugs being scheduled. Some 11.4% indicated use in the prior 12 months. Next year’s survey results should reflect any effects of the scheduling by the DEA."

(Spice) "... a new generation of synthetic cannabinoids has recently emerged on the market, which are sold on the Internet as herbal mixtures under the brand names of “Spice,” “Spice Gold,” “Spice Diamond,” “Arctic Spice,” “Silver,” “Aroma,” “K2,” “Genie,” “Scene” or “Dream,” and advertised as incense products, meditation potpourris, bath additives, or air fresheners. These products are often referred to as “herbal highs” or “legal highs” because of their legal status and purported natural herbal make-up."

(Spice) ‘Spice’ and other ‘herbal’ products are often referred to as ‘legal highs’ or ‘herbal highs’, in reference to their legal status and purported natural herbal make-up (McLachlan, 2009; Lindigkeit et al., 2009; Zimmermann et al., 2009). However, albeit not controlled, it appears that most of the ingredients listed on the packaging are actually not present in the ‘Spice’ products and it is seems likely that the psychoactive effects reported are most probably due to added synthetic cannabinoids, which are not shown on the label. There is no evidence that JWH, CP and/or HU [three chemically distinct groups of synthetic cannabinoids] compounds are present in all ‘Spice’ products or even batches of the same product. Different amounts or combinations of these substances seem to have been used in different ‘Spice’ products to produce cannabis-like effects. It is possible that substances from these or other chemical groups with a cannabinoid agonist or other pharmacological activity could be added to any herbal mixture (¹⁷) (Griffiths et al., 2009).
"The emergence of new, smokable herbal products laced with synthetic cannabinoids can also be seen as a significant new development in the field of so-called ‘designer drugs’. With the appearance, for the first time, of new synthetic cannabinoids, it can be anticipated that the concept of ‘designer drugs’ being almost exclusively linked to the large series of compounds with phenethylamine and tryptamine nucleus will change significantly (¹⁸). There are more than 100 known compounds with cannabinoid receptor activity and it can be assumed that further such substances from different chemical groups will appear (with direct or indirect stimulation of CB1 receptors)."

(K2 and Spice) "Clemson University Professor John Huffman is credited with first synthesizing some of the cannabinoids, such as JWH-018, now used in “fake pot” substances such as K2. The effects of JWH-018 can be 10 times stronger than those of THC. Dr. Huffman is quoted as saying, “These things are dangerous—anybody who uses them is playing Russian roulette. They have profound psychological effects. We never intended them for human consumption.”"

(Spice Prohibition) "Because of health concerns and the abuse potential of herbal incense products, many have been banned in several European countries, 18 U.S. states, and the U.S. military.^33,38 In March 2011, the FDA placed 5 synthetic cannabinoids (JWH-018, JWH-073, JWH-200, CP-47,497, and cannabicyclohexanol) on Schedule I, making them illegal to possess or sell in the United States.³⁸"

(Scheduling of Spice) "On March 1, 2011, the DEA used its temporary scheduling authority and issued a final rule to place five synthetic cannabinoids on the list of controlled substances under Schedule I of the CSA.26 The five substances are
"• 1-pentyl-3-(1-naphthoyl)indole (JWH-018);
"• 1-butyl-3-(1-naphthoyl)indole (JWH-073);
"• 1-[2-(4-morpholinyl)ethyl]-3-(1-naphthoyl)indole (JWH-200);
"• 5-(1,1-dimethylheptyl)-2-[(1R,3S)-3-hydroxycyclohexyl]-phenol (CP-47,497); and
"• 5-(1,1-dimethyloctyl)-2-[(1R,3S)-3-hydroxycyclohexyl]-phenol (cannabicyclohexanol; CP-47,497 C8 homologue).
"Pursuant to the temporary scheduling authority, these substances will remain on the list of Schedule I controlled substances for one year, and then may be given one six-month temporary extension. To remain on Schedule I thereafter, the substances would need to be permanently scheduled within the CSA."

(State Spice Bans) According to the National Alliance for Model State Drug Laws, almost all of the 50 states (except Michigan) had legislation concerning synthetic cannabinoids either introduced or passed as of October 31, 2011.

(Limits on Research) "There is shared concern among researchers that adding these substances to Schedule I could hinder medical research. As previously mentioned, Professor Huffman did not intend for K2 to be consumed by humans. He is, however, against adding synthetic cannabinoids to Schedule I, asserting that there is still much to learn about synthetic cannabinoids and that placing them on Schedule I would create too many hurdles for researchers who need to access these drugs.⁵⁸ Professor Huffman has created several synthetic cannabinoids that are seen as showing promise in treating skin cancers, pain, and inflammation."

(Testing for Use of Synthetics) "Most of the synthetic cannabinoids added as not-listed ingredients to Spice products are very difficult to detect by commonly used drug screening procedures. Apart from the analogs of THC such as HU-210, the structure of these new synthetic cannabinoids differs from that of THC, so that they probably will not trigger a positive test for cannabinoids in immunoassays of body fluids."

(Monitoring of New Drugs) "A dramatic online snapshot of the Spice phenomenon as an emerging trend has been recently given by an important web mapping program, the Psychonaut Web Mapping Project, a European Commission-funded project involving researchers from seven European countries (Belgium, Finland, Germany, Italy, Norway, Spain, and UK), which aims to develop a web scanning system to identify newly marketed psychoactive compounds, and their combinations (e.g., ketamine and Spice, cannabis and Spice), on the basis of the information available on the Internet (Psychonaut Web Mapping Research Group, 2010). As a major result of the Project, a new and updated web-based database is now widely accessible to implement a regular monitoring of the web for novel and recreational drugs."

Marijuana - Other & Miscellaneous

(Effects of Cannabis Prohibition) "Increased funding for cannabis prohibition has increased cannabis seizures and arrests, but the assumption that this reduces cannabis potency, increases price or meaningfully reduces availability or use is inconsistent with surveillance data the US federal government has itself collected."

(Taxonomy) "The biological (reproductive) definition of a species states that all specimens of a population are of a single species if they are naturally able to sexually reproduce, generating fertile offspring. This is the case throughout the genus Cannabis, and by this definition, therefore, there are no clear biological grounds to separate it into different species.However, within the species Cannabis sativa L., several subspecies are sometimes identified (Small and Cronquist, 1976).
"Despite this, modern Cannabis taxonomy remains confused, as a scientific minority prefers to define species according to their typological or morphological characteristics. In 1974, Schultes et al. described three putative species, Cannabis sativa L. (a typically tall species used for fibre, seed or psychoactive use), Cannabis indica Lam. (a short, wide-leafed plant from Afghanistan, used to produce resin) and Cannabis ruderalis Jan. (a short unbranched roadside plant with minimal drug content)."

(THC Content) "The secretion of THC is most abundant in the flowering heads and surrounding leaves. The amount of resin secreted is influenced by environmental conditions during growth (light, temperature and humidity), sex of the plant, and time of harvest. The THC content varies between parts of the plant: from 10-12 % in flowers, 1-2 % in leaves, 0.1-0.3 % in stalks, to less than 0.03 % in the roots."

(History) "There are indications that cannabis was used as early as 4000 B.C. in Central Asia and north-western China, with written evidence going back to 2700 B.C. in the pharmacopeia of emperor Chen-Nong. It then gradually spread across the globe, to India (some 1500 B.C., also mentioned in Altharva Veda, one of four holy books about 1400 B.C.¹), the Near and Middle East (some 900 B.C.), Europe (some 800 B.C.), various parts of South-East Asia (2nd century A.D.), Africa (as of the 11th century A.D.) to the Americas (19th century) and the rest of the world.²"

(Political History) "The identification of cannabis as a potentially dangerous psychoactive substance did not, however, prevent a substantial number of these enquiries to explore the issue of whether current legislation reflected the real dangers posed by cannabis. Already in 1944, the La Guardia Committee Report on Marihuana concluded that ‘the practice of smoking marihuana does not lead to addiction in the medical sense of the word’ and that ‘the use of marihuana does not lead to morphine or heroin or cocaine addiction’ (Zimmer and Morgan, 1997). In 1968 the Wootton Report stated that ‘the dangers of cannabis use as commonly accepted in the past and the risk of progression to opiates have been overstated’ and ‘cannabis is less harmful than other substances (amphetamines, barbiturates, codeine-like compounds)’. A similar conclusion was arrived at 34 years later in 2002 when the Advisory Committee on Drug Dependence proposed the reclassification of cannabis from Class B to Class C (enforced by law in 2004 and confirmed in 2005). These views were reiterated by other enquiries, such as the Baan Committee in the Netherlands, which affirmed in 1971 that ‘cannabis use does not lead directly to other drug use’ (¹⁶) or by the US National Commission on Marihuana and Drug Abuse, which in 1973 stated that ‘the existing social and legal policy is out of proportion to the individual and social harm engendered by the use of the drug [cannabis]’ (¹⁷). The Canadian Le Dain Commission saw ‘the UN Single Convention of 1961 as responsible’ for such a situation which ‘might have reinforced the erroneous impression that cannabis is to be assimilated to the opiate narcotics’. The same commission, however, suggested that the UN Convention did ‘not prevent domestic legislation from correcting this impression’ (¹⁸)."

(Official Descriptions)
"Cultivated Sinsemilla: Female cannabis plant which has not been pollinated. May grow from cutting or from seed. May contain some seed (if un-pollinated the seed will be sterile). Common illicit indoor grow technique.
"Cultivated Non Sinsemilla: Male or Female cannabis plant commonly grown for illicit drug use.
"Cultivated Ditchweed: Male or Female cannabis plant which grows wild in many states that has in some way been tended by man. Examples of tending are: weeding, watering, topping, fertilizing, harvesting.
"Ditchweed: Unattended, wild male or female cannabis that is native to many states.
"Cannabis Bud: Flowering top of a female cannabis plant. The Bud may contain seed. Most valuable portion of a cannabis plant to the illicit grower. Bud formation occurs late in plant development.
"Leaf: Cannabis leaf potency tends to correlate to position on the plant. The most potent part of the plant is the new leaves at the top of the plant. As you move downward on the plant potency decreases. The least potent leaves on the plant are the large leaves at the bottom of the plant.
"Mature Cannabis: Mature cannabis plants have a higher potency than immature plants. Determination of plant maturity should be made using all available contextual factors. For example, is the plant outdoors and it only June or July, if so, then the plant is likely immature. However, if the growing season is near an end, such as September or October, then the plant is probably mature. Note male cannabis plants are mature as early as August when grown outdoors. It is more difficult to generalize regarding maturity of indoor grows. “Spike” cannabis plants can mature in as little as 6-8 weeks whereas an indoor grow with plants 3-4 feet in height may take 60-120 days to mature.
"Already Harvested: Cannabis plant material recently dried or packaged. May be either bud or leaf.
"Average Plant Canopy Diameter: Record the diameter of a typical mature cannabis plant at its broadest point through the center. Diameter data can be used to predict usable yield with good accuracy."

(Effects of Prohibition) "Prohibition has two effects: on one hand it raises supplier costs, disrupts market functioning and prevents open promotion of the product; on the other, it sacrifices the authorities’ ability to tax transactions and regulate operation of the market, product characteristics and promotional activity of suppliers. The cannabis prevalence rates presented in Figure 1 show clearly that prohibition has failed to prevent widespread use of the drug and leaves open the possibility that it might be easier to control the harmful use of cannabis by regulation of a legal market than to control illicit consumption under prohibition. The contrast between the general welcome for tobacco regulation (including bans on smoking in public places) and the deep suspicion of prohibition policy on cannabis is striking and suggests that a middle course of legalised but limited consumption may find a public consensus."

(Marijuana Tax Act) "Marijuana essentially became illegal in 1937 pursuant to the Marijuana Tax Act.³⁹ The use of marijuana required the payment of a tax for usage; failure to pay the tax resulted in a large fine or stiff prison time for tax evasion.⁴⁰ Drug prohibition was elevated to another level by targeting “marijuana,” a plant that had never demonstrated any harm to anyone.⁴¹
"Anslinger’s [Harry J. Anslinger, the first Commissioner of the Federal Bureau of Narcotics] efforts to eradicate marijuana continued when Anslinger sought similar anti-narcotic laws against marijuana at the state level.⁴² Guided by Anslinger’s policy direction, states began passing their own laws or adopting more strident versions of federal laws.⁴³ By 1952, nearly all states had anti-narcotic laws in place.⁴⁴"

Marijuana - Tables

(Cannabis Potency by Year) The Cannabis Potency Monitoring Project, product of a grant from the National Institute on Drug Abuse, is based at the University of Mississippi's School of Pharmacy. Each year since 1975, the Project has issued reports concerning the THC levels of seized cannabis samples sent to them by law enforcement officials. The figures in the following table were published in March 2009.

Note: Applying three-year moving averages to smooth the data and iron out peaks and valleys finds that the three-year average percentage change in cannabis potency from 2005 to 2008 was +3.9% for commercial 'marijuana', -1.3% for 'sensimilla,' and +6.6% for 'kilobricks.' Average changes for loose-leaf, CBD, CBC, and CBN were negligible.

The most recent three-year average potency values for these seized samples were 5.8% THC for commercial 'marijuana,' 11.2% THC for 'sinsimilla,' 9.9% THC for 'buds,' 6.5% THC for 'kilobricks,' and 2.1% THC for 'loose-leaf.' The most recent three-year moving potency averages for the cannibinoids were 0.47% for CBC, 0.30% for CBC, and 0.26% for CBN.

^{Notes: All numbers are percentages. The THC percentages are "Non-normalized Delta-9 THC Concentrations in Different Forms by Year Confiscated 1985 - Present," and cannabinoid percentages (CBD, CBC, CBN) are "Non-Normalized Cannabinoid Averages of Illicit Cannabis Samples by Year Seized." The cannabinoids CBN = Cannabidiol, CBC = Cannabichromene and CBN = Cannabinol.}

Data Tables

(Total Annual Arrests by Year and Category) Although the intent of a 'War on Drugs' may have been to target drug smugglers and 'King Pins,' according to the FBI's annual Uniform Crime Reports nearly half (49.5%) of the 1,531,251 arrests for drug abuse violations in 2011 were for marijuana -- a total of 757,969. Of those, an estimated 663,032 arrests (43.3% of all drug arrests) were for marijuana possession alone. By contrast in 2000, a total of 734,497 Americans were arrested for marijuana offenses, of which 646,042 (40.9%) were for possession alone.

(Total Annual Marijuana Arrests and Total Drug arrests) (Note: Totals are contained in Annual Arrests data table.)

(Percent Change in Arrests Totals 1996-2010) (Note: Totals are contained in Annual Arrests data table.)