"Our results indicate a moderate relation between early teen marijuana use and young adult abuse of other illicit substances; however, this association fades from statistical significance with adjustments for stress and life-course variables. Likewise, our findings show that any causal influence of teen marijuana use on other illicit substance use is contingent upon employment status and is short-term, subsiding entirely by the age of 21. In light of these findings, we urge U.S. drug control policymakers to consider stress and life-course approaches in their pursuit of solutions to the 'drug problem.'"

Is Marijuana Addictive? The best scientific data available indicate that marijuana is less potentially addictive than many other substances in common use. This should not be construed as meaning that marijuana has no potential for dependence or that it is entirely safe.

"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."

"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%)."

"The global market for hemp consists of more than 25,000 products in nine submarkets: agriculture, textiles, recycling, automotive, furniture, food and beverages, paper, construction materials, and personal care (Table 1). Hemp can be grown as a fiber, seed, or dual-purpose crop.⁶ The stalk and seed are the harvested products. The interior of the stalk has short woody fibers called hurds; the outer portion has long bast fibers. Hemp seed/grains are smooth and about one-eighth to one-fourth of an inch long.⁷

"Hemp fibers are used in fabrics and textiles, yarns and spun fibers, paper, carpeting, home furnishings, construction and insulation materials, auto parts, and composites. Hurds are used in animal bedding, material inputs, papermaking, and oil absorbents. Hemp seed and oilcake are used in a range of foods and beverages (e.g., salad and cooking oil and hemp dairy alternatives) and can be an alternative food and feed protein source.8 Oil from the crushed hemp seed is used in soap, shampoo, lotions, bath gels, and cosmetics.⁹ Hemp is also being used in nutritional supplements and in medicinal and therapeutic products, including pharmaceuticals. It is also used in a range of composite products. Hempcrete (a mixture of hemp hurds and lime products) is being used as a building material. Hemp is also used as a lightweight insulating material and in hemp plastics and related composites for use as a fiberglass alternative by the automotive and aviation sectors.¹⁰ Hemp is also promoted as a potential biodiesel feedstock¹¹ and cover crop.

"These types of commercial uses are widely documented in a range of feasibility and marketing studies conducted by researchers at USDA and various land grant universities and state agencies. (A listing of these studies is in the Appendix A.) Currently, finished hemp products and raw material inputs are mostly imported into the United States and sold for use in further processing and manufacturing for a wide range of products."

"This study of crash risk found a statistically significant increase in unadjusted crash risk for drivers who tested positive for use of illegal drugs (1.21 times), and THC specifically (1.25 times). However, analyses incorporating adjustments for age, gender, ethnicity, and alcohol concentration level did not show a significant increase in levels of crash risk associated with the presence of drugs. This finding indicates that these other variables (age, gender, ethnicity and alcohol use) were highly correlated with drug use and account for much of the increased risk associated with the use of illegal drugs and with THC.

"This study found a statistically significant association between driver alcohol level and crash risk both before and after adjustment for demographic factors. These findings were generally consistent with similar analyses conducted in prior crash risk studies. Findings from this study indicate that crash risk grows exponentially with increasing BrAC. The study shows that at low levels of alcohol (e.g., 0.03 BrAC) the risk of crashing is increased by 20 percent, at moderate alcohol levels (0.05 BrAC) risk increases to double that of sober drivers, and at a higher level (0.10 BrAC) the risk increases to five and a half times. At a BrAC of 0.15, the risk is 12 times, and by BrACs of 0.20+ the risk is over 23 times higher."

"The costs of this national obsession, in both money and time, are astonishing. Each year, enforcing laws on possession costs more than $3.6 billion, according to the American Civil Liberties Union. It can take a police officer many hours to arrest and book a suspect. That person will often spend a night or more in the local jail, and be in court multiple times to resolve the case. The public-safety payoff for all this effort is meager at best: According to a 2012 Human Rights Watch report that tracked 30,000 New Yorkers with no prior convictions when they were arrested for marijuana possession, 90 percent had no subsequent felony convictions. Only 3.1 percent committed a violent offense."
* Important here to note that New York is a decriminalized state, that is, personal possession of less than 25 grams of marijuana by an adult is supposedly decriminalized.

"It was not until 1951, when Congress again took up the issue, that a reputable researcher was called to testify. Dr. Harris Isbell, director of research at the Public Health Service Hospital in Lexington, Ky., disputed the insanity, crime and addiction theories, telling Congress that 'smoking marijuana has no unpleasant aftereffects, no dependence is developed on the drug, and the practice can easily be stopped at any time.'
"Despite Dr. Isbell’s testimony, Congress ratcheted up penalties on users. The states followed the federal example; Louisiana, for instance, created sentences ranging from five to 99 years, without parole or probation, for sale, possession or administration of narcotic drugs. The rationale was not that marijuana itself was addictive — that argument was suddenly relinquished — but that it was a 'steppingstone' to heroin addiction. This passed largely without comment at the time.
"The country accepted a senselessly punitive approach to sentencing as long as minorities and the poor paid the price. But, by the late 1960s, weed had been taken up by white college students from the middle and upper classes. Seeing white lives ruined by marijuana laws altered public attitudes about harsh sentencing, and, in 1972, the National Commission on Marihuana and Drug Abuse released a report challenging the approach."

The Times misses part of the story when they write:
"Marijuana was found -- alone or in combination with other drugs -- in more than 455,000 patients visiting emergency rooms in 2011."
http://www.nytimes.com...

A drug mention does not mean that the drug is what caused the visit. Rather, it simply means that the substance was in their system. Arguably, drug mentions in an emergency room may have some meaning yet unless the drug is at fault, those mentions are merely an indicator of prevalence of use:
"DAWN captures drugs that are explicitly named in the medical record as being involved in the ED visit. The relationship between the ED visit and the drug use need not be causal. That is, an implicated drug may or may not have directly caused the condition generating the ED visit; the ED staff simply named it as being involved." (p. 15)

According to the DAWN report, "Of the approximately 2.5 million drug misuse or abuse ED visits that occurred during 2011, a total of 1,252,500, or just over half (50.9%), involved illicit drugs (Table 4). A majority (56.3%) of illicit drug ED visits involved multiple drugs. Overall, 27.9 percent of visits involving illicit drugs also involved alcohol.
"Cocaine and marijuana were the most commonly involved drugs, with 505,224 ED visits (40.3%) and 455,668 ED visits (36.4%), respectively. Cocaine and marijuana were followed by heroin, at 258,482 ED visits, or 20.6 percent, and then by amphetamines/methamphetamine, at 159,840 visits, or 12.8 percent." (DAWN ED Report 2011, p. 25)

"Compelling evidence in other states suggest racial disparities persist or have become worse after legalization and the opening of a licensed marijuana market, even while total marijuana-related criminal justice incidents have decreased.

"In Colorado, marijuana court filings decreased by 85% from 2010 to 2014 after legalizing marijuana in 2012. During the same time frame the rate of arrests for marijuana possession among African Americans/Blacks remained 2.4 times higher compared to the arrest rate for whites. The disparities for African American/Blacks were even larger for arrests for marijuana cultivation (2.5 times the arrest rate for whites) and distribution of marijuana (5.4 times the arrest rate for whites).¹³

"Results from Oregon are consistent with findings in Colorado. The Oregon Public Health Division examined changes in the age-adjusted rates of marijuana arrests by racial groups.14 The age adjusted rate of marijuana arrests for African Americans/Blacks was 2 to 3 times the rate of whites during 2010–2014. Oregon legalized marijuana in 2014 and in the following year the disparity between African Americans/Blacks and whites persisted. Specifically, the rate of arrest was 77% higher among African Americans/Blacks in 2015 when compared to whites.

"Preliminary results suggest that legalization of marijuana for adults has greatly reduced the number of people arrested and convicted for marijuana-related crimes, yet racial disparities persist in Washington and in other states. Other factors may contribute to sustaining the racial disparities, such as over-policing in low-income neighborhoods, racial profiling, and other racially biased police practices. 15 These inequitable practices may minimize the potential positive impacts of I-502 and marijuana legalization on all communities."

"As noted in the illicit drug use section, an estimated 24.0 million Americans aged 12 or older in 2016 were current users of marijuana (Figure 15). This number of past month marijuana users corresponds to 8.9 percent of the population aged 12 or older (Figure 17). The percentage of people aged 12 or older who were current marijuana users in 2016 was higher than the percentages from 2002 to 2015. This increase in marijuana use among people aged 12 or older reflects the increase in marijuana use by adults aged 26 or older and, to a lesser extent, the increase in marijuana use among young adults aged 18 to 25."

"Marijuana positivity continued its upward climb in both the federally-mandated, safety-sensitive and general U.S. workforces. In oral fluid testing, which detects recent drug use, marijuana positivity increased nearly 75 percent, from 5.1 percent in 2013 to 8.9 percent in 2016 in the general U.S. workforce. Marijuana positivity also increased in both urine testing (2.4% in 2015 versus 2.5% in 2016) and hair testing (7.0% in 2015 versus 7.3% in 2016) in the same population.
"Among the federally-mandated, safety-sensitive workforce, which only utilizes urine testing, marijuana positivity increased nearly ten percent (0.71% in 2015 versus 0.78% in 2016), the largest year-over-year increase in five years.
"In Colorado and Washington, the first states in which recreational marijuana use was legalized, the overall urine positivity rate for marijuana outpaced the national average in 2016 for the first time since the statutes took effect. The increase was more pronounced in Colorado, which increased 11 percent (2.61% in 2015 versus 2.90% in 2016), than in Washington, which increased nine percent (2.82% in 2015 versus 3.08% in 2016). The national positivity rate for marijuana in the general U.S. workforce in urine testing increased four percent (2.4% in 2015 compared to 2.5% in 2016).
"'We have been tracking the trends in marijuana positivity in states that have passed medical and recreational marijuana use statutes for several years now. 2016 is the first year since Colorado and Washington approved recreational use that the rates of year-over-year change were sharply higher than the national average,' said Dr. Sample."

"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."

"Alcohol and marijuana are the two most commonly used substances by teenagers to get high, and a question that is often asked is to what extent does change in one lead to a change in the other. If the substances co-vary negatively (an increase in one is accompanied by a decrease in the other) they are said to be substitutes; if they co-vary positively, they are said to be complements.

"Interestingly, the answer may differ by historical era. Before 2007 patterns of use for the two substances suggested they acted as complements. When marijuana use increased in the late 1970s, so too did alcohol use. Between 1979 and 1992 marijuana use declined and a parallel decline took place in annual, monthly, and daily alcohol use, as well as in binge drinking among 12th graders. As marijuana use increased again in the 1990s, alcohol use again increased with it, although not as sharply. In sum, before 2007 there was little evidence from MTF to support what we have termed “the displacement hypothesis,” which asserts that an increase in marijuana use will lead to a decline in alcohol use, or vice versa.8

"However, since 2007 a new trend has emerged that would be consistent with the “displacement” hypothesis. From 2007 through 2019 alcohol use declined markedly, reaching historic lows in the life of the study. Meanwhile, for most of this time period marijuana use has stayed steady or increased for all age groups. For the first time trends in alcohol and marijuana use are substantially diverging, suggesting that the historical relationship between these two drugs may have changed."

"In 2009-2010, past month marijuana use was reported by 6.8 percent of the U.S. population aged 12 years or older, an increase from 6.4 percent in 2008-2009 (Table C.3). Nine States that were in the top fifth for past month illicit drug use among persons aged 12 or older also were ranked in the top fifth for past month marijuana use: Alaska, Colorado, District of Columbia, Maine, Massachusetts, New Hampshire, Oregon, Rhode Island, and Vermont (Figures 2.1 and 2.9).
"Seven States were ranked in the top fifth for past month marijuana use in age groups 12 to 17, 18 to 25, 26 or older, and 12 or older: Colorado, Maine, Massachusetts, New Hampshire, Oregon, Rhode Island, and Vermont (Figures 2.9 to 2.12). The rate of past month marijuana use in the 12 or older population ranged from 3.1 percent in Utah to 11.8 percent in Alaska (Table B.3). Utah had the lowest rate in all age groups. Between 2008-2009 and 2009-2010, past month marijuana use among persons 12 or older increased in 10 States: Colorado, District of Columbia, Idaho, Illinois, Massachusetts, Michigan, New Mexico, Oklahoma, Texas, and Washington (Table C.3). During the same time period, past month marijuana use increased in one State among 12 to 17 year olds (District of Columbia), eight States among 18 to 25 year olds (Florida, Illinois, Iowa, New Mexico, North Carolina, Oklahoma, Pennsylvania, and Washington), and four States among persons aged 26 or older (District of Columbia, Idaho, Michigan, and Texas). Decreases only occurred in two States: Tennessee, among persons aged 12 or older, and Utah, among youths aged 12 to 17. All four census regions had higher rates of past month marijuana use among persons aged 12 or older in 2009-2010 compared with 2008-2009."

“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).”

"Among 50-year-old high school graduates in 2012, we estimate that about three quarters (74%) have tried marijuana, and that about two thirds (64%) 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 eight (12%) indicates using marijuana in the last 12 months, and one in ten (10%) indicates using any other illicit drug in the same period. Their past-month prevalence rates are lower—7.3% and 6.2%, 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."

Total Number of Sentenced People In Federal Prisons, 2004 = 153,776
Total Number of Sentenced People In State Prisons, 2004 = 1,274,600

Total Number of Sentenced People In Federal Prisons In The US For Whom a Drug Charge Was Their Most Serious Offense, 2004: 85,300 (55.5%)
Total Number of Sentenced People In State Prisons In The US For Whom a Drug Charge Was Their Most Serious Offense, 2004: 249,400 (19.6%)

Percent of sentenced people serving time in federal prisons whose most serious drug charges were marijuana/hashish offenses: 2004 = 12.4%
Percent of sentenced people serving time in state prisons whose most serious drug charges were marijuana/hashish, 2004 = 12.7%

(Sentenced people with drug offenses as their most serious charge) * (percent marijuana) = sentenced people serving time for marijuana offenses

Sentenced people serving time in federal prison on marijuana charges, 2004 = 10,577
Sentenced people serving time in state prisons on marijuana charges, 2004 = 31,674
Total sentenced people serving time on marijuana charges, state and federal prisons combined, 2004 = 42,251

Note: These data only address people in prisons and thus exclude everyone serving time in local jails because of a marijuana conviction.

"• Marijuana was the illicit drug with the largest number of persons with past year dependence or abuse in 2013, followed by pain relievers, then by cocaine. Of the 6.9 million persons aged 12 or older who were classified with illicit drug dependence or abuse in 2013, 4.2 million persons had marijuana dependence or abuse (representing 1.6 percent of the total population aged 12 or older, and 61.4 percent of all those classified with illicit drug dependence or abuse), 1.9 million persons had pain reliever dependence or abuse, and 855,000 persons had cocaine dependence or abuse (Figure 7.2)."
"• The number of persons who had marijuana dependence or abuse in 2013 (4.2 million) was similar to the number in 2012 (4.3 million) and in each year from 2002 through 2011 (ranging from 3.9 million to 4.5 million) (Figure 7.3). The rate of marijuana dependence or abuse in 2013 (1.6 percent) was lower than the rates in 2002 (1.8 percent) and 2004 (1.9 percent). Otherwise, the rate in 2013 was similar to the rates in prior years (ranging from 1.6 to 1.8 percent).
"• The number of persons who had pain reliever dependence or abuse in 2013 (1.9 million) was similar to the number in 2012 (2.1 million) and in each year from 2006 through 2011 (ranging from 1.6 million to 1.9 million) (Figure 7.3). However, the number in 2013 was higher than the numbers in 2002 to 2005 (ranging from 1.4 million to 1.5 million)."

According to the Substance Abuse and Mental Health Service's Treatment Episode Data Set, in 2015 in the US there were 213,001 admissions to treatment with marijuana reported as the primary substance of abuse out of the total 1,537,025 admissions to treatment in the US for those aged 12 and older for all substances that year. This is the lowest number of marijuana admissions and total treatment admissions in at least a decade: marijuana admissions peaked in 2009 at 373,338, and total admissions peaked in 2008 at 2,074,974.

"• 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."

"Police departments deploy most patrol and narcotics police to certain neighborhoods, usually designated "high crime." These are disproportionately low-income, and disproportionately African-American and Latino neighborhoods. It is in these neighborhoods where the police make most patrols, and where they stop and search the most vehicles and individuals, looking for "contraband" of any type in order to make an arrest. The item that young people in any neighborhood are most likely to possess, which can get them arrested, is a small amount of marijuana. In short, the arrests are racially-biased mainly because the police are systematically "fishing" for arrests in only some neighborhoods, and methodically searching only some "fish."⁵ This produces what has been termed "racism without racists."⁶"

"The central finding gleaned from the present study was that MML is not predictive of higher crime rates and may be related to reductions in rates of homicide and assault. Interestingly, robbery and burglary rates were unaffected by medicinal marijuana legislation, which runs counter to the claim that dispensaries and grow houses lead to an increase in victimization due to the opportunity structures linked to the amount of drugs and cash that are present. Although, this is in line with prior research suggesting that medical marijuana dispensaries may actually reduce crime in the immediate vicinity [8]."

"Given that the current results failed to uncover a crime exacerbating effect attributable to MML, it is important to examine the findings with a critical eye. While we report no positive association between MML and any crime type, this does not prove MML has no effect on crime (or even that it reduces crime). It may be the case that an omitted variable, or set of variables, has confounded the associations and masked the true positive effect of MML on crime. If this were the case, such a variable would need to be something that was restricted to the states that have passed MML, it would need to have emerged in close temporal proximity to the passage of MML in all of those states (all of which had different dates of passage for the marijuana law), and it would need to be something that decreased crime to such an extent that it ‘‘masked’’ the true positive effect of MML (i.e., it must be something that has an opposite sign effect between MML [e.g., a positive correlation] and crime [e.g., a negative correlation]). Perhaps the more likely explanation of the current findings is that MML laws reflect behaviors and attitudes that have been established in the local communities. If these attitudes and behaviors reflect a more tolerant approach to one another’s personal rights, we are unlikely to expect an increase in crime and might even anticipate a slight reduction in personal crimes."

"• Marijuana/hashish was reported as the primary substance of abuse by 15 percent of TEDS admissions aged 12 and older in 2014 [Table 1.1b].
"• The average age at admission for primary marijuana/hashish admissions was 26 years [Table 2.1b], although the peak age at admission for both genders in all race/ethnicities was about 16 to 17 years [Figure 12]. Thirty-two percent of marijuana/hashish admissions were under age 20 (vs. 8 percent of all admissions combined), and primary marijuana/hashish abuse accounted for 78 percent of admissions aged 12 to 14 and 76 percent of admissions aged 15 to 17 years [Table 2.1c].
"• Non-Hispanic Whites accounted for 44 percent of primary marijuana/hashish admissions (30 percent were males and 14 percent were females), and non-Hispanic Blacks accounted for 31 percent (24 percent were males and 8 percent were females) [Table 2.3b].
"• Twenty-four percent of primary marijuana/hashish admissions had first used marijuana/hashish by age 12 and another 30 percent had first used it by age 14 [Table 2.5b].
"• Primary marijuana/hashish admissions were most likely to be referred by the court/criminal justice system (52 percent). Primary marijuana/hashish admissions were less likely than all admis-sions combined to be self- or individually referred to treatment (18 vs. 37 percent) [Table 2.6b].
"• More than 4 in 5 marijuana/hashish admissions (86 percent) received ambulatory treatment; among all admissions combined, 3 in 5 (61 percent) received ambulatory treatment [Table 2.7b].
"• Sixty-three percent of primary marijuana/hashish admissions reported abuse of additional sub-stances. Alcohol was reported by 37 percent [Table 3.8]."

"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."

Click here for the complete datatable of Average Tetrahydrocannabinol (THC), Cannabidiol (CBD), and Cannabinol (CBN) Levels of Seized Samples of Domestic Cannabis in the US, 1995-2015

"• Twenty-three Police Forces in England and Wales participated in the study. Forces were requested to submit samples confiscated from street-level users. In early 2008, they submitted 2,921 samples for analysis to either the Forensic Science Service Ltd (FSS) or LGC Forensics at Culham (LGC F).
"• Initial laboratory examination showed that 80.8% were herbal cannabis and 15.3% were cannabis resin. The remaining 3.9% were either indeterminate or not cannabis.
"• Microscopic examination of around two-thirds of the samples showed that over 97% of the herbal cannabis had been grown by intensive methods (sinsemilla). The remainder was classed as traditional imported herbal cannabis.
"• Regional variations were found in the market share of herbal cannabis. Thus North Wales, South Wales, Cleveland and Devon and Cornwall submitted proportionately fewer herbal cannabis samples, whereas Essex, Metropolitan and Avon and Somerset submitted proportionately more. These differences were statistically significant at the 0.1% confidence interval.
"• 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.
"• There was a weak, but statistically-significant, correlation (r = 0.48; N = 112; P < 0.001) between the THC and the CBD content of resin."

"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."

"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."

"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."

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.

"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."

"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 ..."

"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. Nonetheless, certain logistic properties of marijuana smoking may increase the risk of carcinogenic exposure compared with conventional tobacco smoking, raising questions as to why observational studies have not demonstrated an association with lung cancer."

"Nonetheless, and contrary to our expectations, we found no positive associations between marijuana use and lung or UAT cancers. Although we observed positive dose-response relations of marijuana use to oral and laryngeal cancers in the crude analyses, the trend was no longer observed when adjusting for potential confounders, especially cigarette smoking. In fact, we observed ORs <1 for all cancers except for oral cancer, and a consistent monotonic association was not apparent for any outcome. Similar findings were found when the analyses were restricted to subjects who never smoked cigarettes. The 95% confidence intervals for the adjusted ORs did not extend far above 1 (e.g., were under 2 for marijuana and lung cancer), which suggests that associations of marijuana use with the study cancers are not strong and may be below detectable limits for this type of study."

"In the current study, we demonstrated that chronic cannabis smokers had relative visceral adiposity and adipose tissue insulin resistance but not hepatic steatosis, glucose insulin insensitivity, impaired pancreatic b-cell function, glucose intolerance, or dyslipidemia compared with age-, sex-, ethnicity-, and BMI-matched control individuals. Our study results suggest that chronic, daily cannabis use may have differential tissue-specific effects on insulin sensitivity, but these effects appear to have minimal impact on glucose or lipid metabolism."

Marijuana use is associated with higher daily caloric intake. In the NHANES III and CARDIA study, heavy cannabis users had ;20% higher calorie intake than nonusers (25,26). The increase in calories was from higher intake of all macronutrients. Specifically, the frequency and amount of consumption of soda, cheese, salty snacks, pork, and alcohol was higher in cannabis users. Consistent with other studies, the quality of diets consumed by cannabis users was poor (27). Furthermore, the percent of daily calories derived from carbohydrates relatively rich in simple sugars was significantly higher in marijuana smokers. These findings are consistent with human and animal studies demonstrating that cannabinoids stimulate food intake, specifically highly palatable sweet-tasting foods (28). Cannabis smokers in our study exhibited characteristics typically observed in marijuana smokers in the general population."

"As research on pharmacological treatments for CUD continues, a few key findings are of note. First, cannabinoid agonists (nabilone, dronabinol in combination with lofexidine, and lofexidine alone), were the only drugs that decreased drug-taking in a human laboratory model of relapse, supporting the notion that agonist replacement and attenuation of noradrenergic activity show promise for relapse prevention. Although dronabinol alone failed to clinically reduce cannabis use, a higher dose might have been more effective. Further, that study was designed to evaluate the initiation of abstinence; dronabinol or the more bioavailable agonist nabilone, might have greater utility in the prevention of relapse [25•]. These studies also support further testing of lofexidine in combination with other drugs, and generally illustrate the utility that can be gained from combining medications.
"Second, gabapentin and NAC were the only drugs tested in placebo-controlled clinical trials that decreased cannabis use (abstinence induction). Third, the ability of a drug to reduce cannabis withdrawal symptoms is not predictive of its ability to alter drug-taking behaviors (reduce use or prevent relapse). However, all the studies that reported positive changes in drug use also reported a reduction in withdrawal during early abstinence, suggesting that this feature is an important component of an efficacious medication."

"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."

"This study among 98 experienced cannabis smokers is the first naturalistic study to examine whether users of cannabis with high THC concentration titrate the psychoactive effects by using lower doses and/or by reduced inhalation, and whether cannabis smoking behaviour (topography) predicts cannabis dependence severity independently of total THC exposure.
"In contrast to our hypothesis, there was a positive association between cannabis THC concentration and cannabis dose, indicating that users of stronger cannabis generally used larger amounts of cannabis to prepare their regular joint. However, in line with our hypothesis, the negative association between THC concentration of joints and total inhaled smoke volume indicates that users of stronger joints inhaled smaller smoke volumes, thus resulting in partial titration of the total THC exposure. Overall, as exemplified by the comparison of the average user with the user with the maximum THC concentration, users of high-potency cannabis will generally be exposed to higher total doses of THC (at least in this sample). This is in line with Cappell et al.’s observations through a one-way mirror experiment in 1973 where users only partly adapted their intake [14]. Indeed, increased THC concentrations of cannabis have recently been linked to increased internal THC exposure assessed in blood [28]."

"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."

"There is no conclusive evidence that the drug effects of marijuana are causally linked to the subsequent abuse of other illicit drugs."

"In line with previous work, we found that cannabis users had lower teenage IQ scores and poorer educational performance than teenagers who had never used cannabis. At the same time, cannabis users also had higher rates of childhood behavioural problems, childhood depressive symptoms, other substance use (including use of cigarettes and alcohol) and maternal use of cannabis during pregnancy. After adjustment to account for these group differences, cannabis use by the age of 15 did not predict either lower teenage IQ scores or poorer educational performance. These findings therefore suggest that cannabis use at the modest levels used by this sample of teenagers is not by itself causally related to cognitive impairment. Instead, our findings imply that previously reported associations between adolescent cannabis use and poorer intellectual and educational outcomes may be confounded to a significant degree by related factors."

"Compared with those in our sample who had never tried cannabis, teenagers who had used cannabis at least 50 times were 17 times more likely (84% vs. 5%) to have smoked cigarettes more than 20 times in their lifetime. Accounting for group differences in cigarette smoking dramatically attenuated the associations between cannabis use and both IQ and educational performance. Further, even after excluding those who had never tried cannabis, cigarette users were found to have lower educational performance (adjusted performance 2.9 percentage points lower, approximately equivalent to dropping two grades on one subject taken at GCSE) relative to those who had never tried cigarettes. A relationship between cigarette use and poorer cognitive (Chamberlain et al., 2012; Hooper et al., 2014; Weiser et al., 2010; Whalley et al., 2005) and educational (McCaffrey et al., 2010; Silins et al., 2014; Stiby et al., 2014) outcomes has been noted previously, and may have a number of explanations. Cigarette use may have a negative impact on cognitive ability. However, this is not supported by the experimental psychopharmacology literature, which robustly shows that acute nicotine administration results in transient cognitive enhancement (Heishman et al., 2010). Alternatively, reverse causality may contribute to this relationship, for example performing poorly at school may lead to increased engagement in risky behaviours such as cigarette smoking. Further, residual confounding may contribute to this link: cigarette smoking may be a marker of unmeasured factors, for example social adversity during adolescence, that influence both IQ and educational attainment."

"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."

"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."

"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."

"Other studies have found short term residual effects of cannabis use on memory and cognition (34, 35) that are more severe among women (36) and heavy users (37). However, our data suggest that over the long term cannabis use is not associated with greater declines in cognition among men, women, or heavy users. The study design we used included several of the features proposed by Pope et al. (34) as critical to addressing the long term effects of cannabis on cognition: naturalistic follow-up, a large sample size, a population basis, comparison of light cannabis use with heavy use, and the construction of models accounting for the effects of gender and use of illicit drugs, alcohol, and tobacco. Therefore, these results would seem to provide strong evidence of the absence of a long term residual effect of cannabis use on cognition."

"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."

"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."

"In terms of the model set out in the Introduction, 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). However, it is not in line with findings of a rise in first admission rates for psychotic disorders among young people in Zurich following increases in cannabis availability and consumption (Ajdacic-Gross et al., 2007). One factor involved in this discrepancy may be the potency of the cannabis consumed, which varies considerably within Europe (EMCDDA, 2008). In addition, a Netherlands study found that high-potency cannabis obtained from ‘coffee shops’ led to higher levels of tetrahydrocannabinol (THC) in the blood, with young males aged 18–45 at particular risk for excessive consumption (Mensinga et al., 2006)."

"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."

"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)"

"Annual marijuana prevalence peaked among 12th graders in 1979 at 51%, following a rise that began during the 1960s. Then use declined fairly steadily for 13 years, bottoming at 22% in 1992—a decline of more than half. The 1990s, however, saw a resurgence of use. After a considerable increase (one that actually began among 8th graders a year earlier than among 10th and 12th graders), annual prevalence rates peaked in 1996 at 8th grade and in 1997 at 10th and 12th grades. After these peak years, use declined among all three grades through 2007 or 2008. After these declines, an upturn occurred in use in all three grades, lasting for three years in the lower grades and longer in grade 12. Annual marijuana prevalence among 8th graders increased in use from 2007 to 2010, decreased slightly from 2010 to 2012, and then declined significantly in 2016. Among 10th graders, use increased somewhat from 2008 to 2013 and then declined after that. Among 12th graders, use increased from 2006 to 2011 and then held level through 2016. As shown in Table 8, daily use increased in all three grades after 2007, reaching peaks in 2011 (at 1.3% in 8th), 2013 (at 4.0% in 10th), and 2011 (at 6.6% in 12th), before declining slightly since. Daily prevalence rates in 2016 were 0.7%, 2.5%, and 6.0%, respectively, with one in seventeen 12th graders smoking daily."

"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."

"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."

"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."

"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."

"Overall, 23,591 (90.9%) of the 25,951 drivers who died within 1 hour of a crash in these 6 states underwent toxicological testing. Drivers who were tested for drugs were similar in crash circumstances to those who were not tested, but they appeared to be slightly younger (mean age = 39.4 (standard deviation, 19.4) years vs. 43.4 (standard deviation, 27.7) years), more likely to be male (77.7% vs. 75.8%), more likely to be involved in nighttime crashes (51.4% vs. 47.0%), and more likely to have been involved in a crash in the previous 3 years (15.7% vs. 13.9%) than those who were not tested.
"Of the 23,591 drivers tested, 39.7% were positive for alcohol, and 24.8% tested positive for other drugs. The prevalence of alcohol involvement was stable at approximately 39% from 1999 to 2010 (Z = ?1.4, P = 0.16). Alcohol involvement was more prevalent in men (43.6%) than in women (26.1%), but trends were stable for both sexes (Table 1). In contrast, the prevalence of nonalcohol drugs showed a statistically significant increasing trend over the study period, rising from 16.6% (95% confidence interval (CI): 14.8, 18.4) in 1999 to 28.3% (95% CI: 26.0, 30.7) in 2010 (Z = ?10.19, P < 0.0001). The prevalence rates of non-alcohol drugs and 2 or more nonalcohol drugs increased significantly over the study period in both sexes (Table 1). The prevalence of nonalcohol drug use increased significantly across all age groups (Figure 1)."

"The prevalence of drugs detected in cases was higher than in controls across the drug categories (Table 3). Marijuana, narcotics, stimulants, and depressants were each associated with a significantly increased risk of fatal crash involvement, with estimated odds ratios ranging from 1.83 for marijuana to 4.83 for depressants (Table 3). Polydrug use, defined as use of two or more non-alcohol drugs, was associated with a 3.4-fold increased risk of fatal crash involvement (Table 3).
"About one-fifth (20.5%) of the cases tested positive for alcohol and one or more drugs, compared with 2.2% of the controls. Relative to drivers who tested positive for neither alcohol nor drugs, the estimated odds of fatal crash involvement increased over 13 folds for those who were alcohol-positive but drug-negative, more than two folds for those who were alcohol-negative but drug-positive, and 23 folds for those who were positive for both alcohol and drugs (Table 4)."

"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. THC is rapidly and extensively metabolized with very little THC being excreted unchanged from the body. THC is primarily metabolized to 11-hydroxy-THC which has equipotent psychoactivity. The 11-hydroxy-THC is then rapidly metabolized to the 11-nor-9-carboxy-THC (THC-COOH) which is not psychoactive. A majority of THC is excreted via the feces (~65%) with approximately 30% of the THC being eliminated in the urine as conjugated glucuronic acids and free THC hydroxylated metabolites."

"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."

"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."

"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)."

"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."

"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)."

"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."

"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)."

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."

"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."

"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)."

"In 1968, the National Institute of Mental Health began funding a Drug Supply Program to provide researchers with compounds necessary to conduct biomedical research. Initially, the program focused on THC and other naturally occurring cannabinoids, and then gradually expanded to a wide range of compounds. (Since its beginning, the program has synthesized or obtained over 1,500 different compounds that have been supplied to over 2,500 researchers.) Cannabis was among the first substances to be made available through the Drug Supply Program for use by scientists conducting both nonhuman research and human research under a variety of investigational new drug protocols. It was grown through a contract with the University of Mississippi. With its establishment in 1974, NIDA became the successor to NIMH as the administrator of the cannabis contract and the sole U.S. source for legal cannabis."

"... 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."

"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."

"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)."

"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."

"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."

"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)."

"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."