"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 law enforcement view of marijuana was indelibly shaped by the fact that it was initially connected to brown people from Mexico and subsequently with black and poor communities in this country. Police in Texas border towns demonized the plant in racial terms as the drug of 'immoral' populations who were promptly labeled 'fiends.'

"As the legal scholars Richard Bonnie and Charles Whitebread explain in their authoritative history, 'The Marihuana Conviction,' the drug’s popularity among minorities and other groups practically ensured that it would be classified as a 'narcotic,' attributed with addictive qualities it did not have, and set alongside far more dangerous drugs like heroin and morphine.

"By the early 1930s, more than 30 states had prohibited the use of marijuana for nonmedical purposes. The federal push was yet to come.

"The stage for federal suppression of marijuana was set in New Orleans, where a prominent doctor blamed 'muggle-heads' — as pot smokers were called — for an outbreak of robberies. The city was awash in sensationalistic newspaper articles that depicted pushers hovering by the schoolhouse door turning children into 'addicts.' These stories popularized spurious notions about the drug that lingered for decades. Law enforcement officials, too, trafficked in the 'assassin' theory, under in which killers were said to have smoked cannabis to ready themselves for murder and mayhem."

"Preliminary look at racial disparities in select counties of Washington

"The Crime, Cannabis & Police Research Group at Washington State University used preliminary data from a Department of Justice funded study to compare white vs. Black arrests.¹¹ Latinos were not included in the analysis, because of difficulties measuring ethnicity in arrest data. Their main preliminary findings are that after legalization in Washington, African Americans/Blacks continue to be disproportionally arrested for the possession and selling of marijuana when compared to whites. Though the disparity in marijuana possession between African American/Blacks and whites was reduced slightly after legalization, the disparity for selling marijuana has more than doubled since legalization.

"Local trends

"While statewide studies have the ability to control for individual law enforcement agencies or police departments, monitoring trends in marijuana-related crimes within a local police department can provide details of violations that statewide data systems do not. For example, violations for public consumption of marijuana cannot be directly queried from state-derived data; however, local law enforcement agencies and municipal courts maintain details on the nature of the crime that would indicate whether someone was ticketed for public consumption vs. possession or a different drug-related charge. One example of the potential of local data to explore issues of criminal justice can be made using data from the Seattle Police Department (SPD). A 2015 report for the Seattle Community Police Commission showed a disproportionate number of citations for marijuana public consumption issued to African Americans/Blacks in Seattle.¹² Using local police department data is key to understanding differences in the implementation and enforcement of polices pertaining to the legalization of marijuana."

"In these initial investigations, we found no evidence that I-502 enactment, on the whole, affected cannabis abuse treatment admissions. Further, within Washington State, we found no evidence that the amount of legal cannabis sales affected cannabis abuse treatment admissions.

"The bulk of outcome analyses in this report used the within-state approach to focus on identifying effects of the amount of legal cannabis sales. We found no evidence that the amount of legal cannabis sales affected youth substance use or attitudes about cannabis or drug-related criminal convictions.

"We did find evidence that higher levels of retail cannabis sales affected adult cannabis use in certain subgroups of the population. BRFSS respondents 21 and older who lived in counties with higher levels of retail cannabis sales were more likely to report using cannabis in the past 30 days and heavy use of cannabis in the past 30 days.

"We also found two effects that are difficult to interpret. Among the portion of the population aged 18 to 21, BRFSS respondents living in counties with higher sales were less likely to report using cannabis in the past 30 days, in some analyses. It may be that legal cannabis sales have made cannabis more difficult to access by persons below the legal age, for instance, by reducing black market supply through competition.

"We also found that in the portion of the BRFSS sample who smoked cigarettes, respondents living in counties with higher levels of legal cannabis sales were less likely to report past-month cannabis use. It is particularly difficult to explain why increased sales would lead to lower cannabis use among cigarette smokers."

In 2019, law enforcement agencies in the US made an estimated 10,085,207 arrests for all offenses, of which 1,558,862 were drug arrests.

Although the intent of a 'War on Drugs' may have been to target drug smugglers and 'King Pins,' of the 1,558,862 arrests for drug law violations in 2019, 86.7% (1,351,533) were for mere possession of a controlled substance. Only 13.3% (207,329) were for the sale or manufacturing of a drug. Further, 35.0% of drug arrests in 2019 were for marijuana offenses -- a total of 545,602. Of those, an estimated 500,395 arrests (32.1% 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.

Table: Total Annual Arrests in the US by Year and Type of Offense, 1996-2019

"One area representative, from New York City, reported the continuing predominance in indicators and serious consequences of marijuana (as well as heroin and cocaine) and changes in marijuana trends as a key finding in that area for this reporting period. Marijuana indicator levels continued to be reported as high relative to other drugs, however, across all CEWG areas, based on treatment admissions and reports identified as marijuana/cannabis among drug items seized and analyzed. New marijuana/cannabis laws legalizing both medical and recreational marijuana use were expected by area representatives to be influencing indicators in several areas currently and in the future. Representatives from Texas and Chicago reported a shift in trafficking and marketing away from Mexican marijuana (due to a drought and poor quality Mexican marijuana) to local markets and local 'grow' operations."

"Hemp fields, in fact, could be a deterrent to marijuana growers. A strong case can be made that the best way to reduce the THC level of marijuana grown outdoors would be to grow industrial hemp near it. An experiment in Russia found that hemp pollen could travel 12 kilometers. This would mean that a hemp field would create a zone with a 12-kilometer radius within which no marijuana grower would want to establish a crop.

"The reciprocal also applies. Growers of hemp seed would not want Cannabis of an 'off type' (i.e., not the intended genetic type) mixing its pollen with their flowers. The isolation of genotypes is a common procedure used by the seed industry to preserve the genetic integrity of varieties. Valued strains are created by plant breeding, at substantial expense. Marijuana pollen would destroy this value."

"Several limitations of the present study should also be addressed. The PET data used in this study were collected on a separate sample of young adults, not the 799 youths who underwent longitudinal neuroimaging. Given the invasive nature of PET imaging and its associated risks, it is not ethical to collect PET data on minors. We cannot state definitively that, in our sample of 799 participants, the areas exhibiting cannabis-related thinning in longitudinal MRI analysis were, in fact, high in CB1 receptor availability. Our present findings are also limited by the self-report nature of our cannabis use measure. As with any self-report measure, it is possible that participants were not honest regarding their cannabis use or that their estimates of past cannabis use were inaccurate. We also did not have information pertaining to the types of cannabis products used (eg, cannabis oil concentrates and other formulations). As in other longitudinal MRI studies, there is uncertainty with regard to the exact neurobiological mechanisms associated with MRI-assessed cortical thinning. Research suggests that MRI-assessed, age-related cortical thinning may reflect increased myelination of lower cortical layers as opposed to synaptic pruning and/or neuronal cell loss.⁵⁷ Natu et al⁵⁷ found good correspondence between MRI-assessed cortical thickness and histologic measurements of cortical thickness among young adults. This latter finding is critical given that we detected cannabis-related differences in cortical thickness at age 19 years and not at 14 years, suggesting that our MRI-assessed cortical thickness findings are associated with reduced cortical gray matter rather than increased myelination. The present study focused on cortical thickness development and did not examine potential cannabis-related outcomes within subcortical structures. Future studies may benefit from conducting similar analyses on subcortical regions, particularly those rich in CB1 receptors. Most important, given the observational nature of the present study, it is possible that the apparent association between cortical thinning and cannabis use reflects preexisting trajectories of brain maturation that were not caused by cannabis use. We cannot rule out the possibility that preexisting cognitive and/or behavioral differences are associated with neurodevelopmental trajectories from adolescence to early adulthood and that cannabis use is not causally related to cerebral cortical thickness development."

"Assessing both CUD [Cannabis Use Disorder] and cannabis use status and their associations with suicidal ideation, plan, and attempt, we found that suicidality trends varied by sex, depression, and both CUD and cannabis use status. Our results suggest that CUD, daily cannabis use, and even nondaily cannabis use were associated with a higher prevalence of suicidal ideation, plan, and attempt more significantly in women than in men. Specifically, the adjusted prevalence of past-year suicidal ideation was higher among women with CUD regardless of MDE [Major Depressive Episode] status and among women without MDE but with daily or nondaily cannabis use compared with their male counterparts. We found upward trends in suicidal ideation among women (rather than men) with MDE and CUD or daily and nondaily cannabis use. Compared with their male counterparts, the adjusted prevalence of suicide plan and attempt were higher among women with MDE and CUD or daily cannabis use and among women without MDE but with CUD or daily and nondaily cannabis use. Similarly, from 2008 to 2019, we found an upward trend in suicide plan among women (rather than men) with MDE and daily cannabis use and an upward trend in suicide attempt among women (rather than men) with MDE and CUD. By contrast, among individuals with neither MDE nor cannabis use, the adjusted prevalence of suicidal ideation, plan, and attempt were similar between men and women, and the adjusted prevalence of suicidal ideation was lower among women with MDE without CUD or cannabis use compared with their male counterparts."

"Our results, along with those from a recent study,⁴⁸ suggest that adults with MDE [Major Depressive Episode] may be particularly vulnerable to cannabis use as beliefs in its therapeutic potential become more widespread and products become more accessible. Moreover, even after adjusting for depression, CUD, cannabis use status, and other potential confounding factors, we found that from 2008 to 2019 among adults aged 18 to 34 years, the adjusted prevalence of suicidal ideation increased 1.4-fold; suicide plan, 1.6-fold; and suicide attempt, 1.4-fold. Furthermore, even for those with neither MDE nor cannabis use, we found upward trends in suicidal ideation and plan among both men and women and in suicide attempt among men. Our results indicate that depression and cannabis use are associated with suicidality but do not appear to be the only causes for the upward trends in suicide among young adults."

"There is a large body of literature describing the diagnosis, pathophysiology, and treatment of CHS [Cannabinoid Hyperemesis Syndrome]. However, most of the evidence is considered low quality because it is in the form of case reports and case series. When these reports are combined, a larger and more robust set of diagnostic characteristics, evaluation of pathophysiology, and determination of effective treatments can be generated. Based on our knowledge of 211 unique CHS patients, the following characteristics are associated with the syndrome: (1) severe cyclic vomiting that is usually accompanied with abdominal pain, (2) symptom onset preceded by at least weekly cannabis use, (3) temporary relief of symptoms with compulsive hot baths/showers, (4) resolution of symptoms with cessation of cannabis use, (5) onset of cannabis use in the teenage years, and (6) symptom onset in the third decade of life. While not all these criteria must be met to make the diagnosis, of 133 cases for which raw data were available, 85 met at least four criteria (75.2%) and 104 (92%) met at least three criteria. Secondary to incomplete and inconsistent reporting of the proposed diagnostic characteristics in the case report literature, the aforementioned data may be an underestimate of the actual occurrence of these symptoms in CHS patients.

"CHS shares many clinical similarities with cyclic vomiting syndrome (CVS), a functional gastrointestinal disorder. A diagnostic dilemma arises when CVS patients concurrently use cannabis, as it can be difficult to discern if the true underlying disorder is CHS or CVS that is being symptomatically managed with cannabis."

"For Michele Leonhart, the administrator of the Drug Enforcement Administration, there is no difference between the health effects of marijuana and those of any other illegal drug. 'All illegal drugs are bad for people,' she told Congress in 2012, refusing to say whether crack, methamphetamines or prescription painkillers are more addictive or physically harmful than marijuana.
"Her testimony neatly illustrates the vast gap between antiquated federal law enforcement policies and the clear consensus of science that marijuana is far less harmful to human health than most other banned drugs and is less dangerous than the highly addictive but perfectly legal substances known as alcohol and tobacco. Marijuana cannot lead to a fatal overdose. There is little evidence that it causes cancer. Its addictive properties, while present, are low, and the myth that it leads users to more powerful drugs has long since been disproved.
"That doesn’t mean marijuana is harmless; in fact, the potency of current strains may shock those who haven’t tried it for decades, particularly when ingested as food. It can produce a serious dependency, and constant use would interfere with job and school performance. It needs to be kept out of the hands of minors. But, on balance, its downsides are not reasons to impose criminal penalties on its possession, particularly not in a society that permits nicotine use and celebrates drinking."

"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.

"Worldwide, there were an estimated 192 million past-year users of cannabis in 2018, corresponding to 3.9 per cent of the global population aged 15–64. The past-year use of cannabis is substantially higher than the global average in North America (14.6 per cent), Australia and New Zealand (10.6 per cent) and West and Central Africa (9.3 per cent).

"In 2009, cannabis use was reported to be stabilizing or declining in countries with established cannabis markets, such as in Western and Central Europe, North America and Australia and New Zealand, but that trend was offset by increasing use in many countries in Africa and Asia.²¹ A decade later, cannabis use in Western and Central Europe has remained stable overall and has increased considerably in North America, Africa and Asia.²²"

"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."

"Although the mean annual opioid analgesic overdose mortality rate was lower in states with medical cannabis laws compared with states without such laws, the findings of our secondary analyses deserve further consideration. State-specific characteristics, such as trends in attitudes or health behaviors, may explain variation in medical cannabis laws and opioid analgesic overdose mortality, and we found some evidence that differences in these characteristics contributed to our findings. When including state-specific linear time trends in regression models, which are used to adjust for hard-to-measure confounders that change over time, the association between laws and opioid analgesic overdose mortality weakened. In contrast, we did not find evidence that states that passed medical cannabis laws had different overdose mortality rates in years prior to law passage, providing a temporal link between laws and changes in opioid analgesic overdose mortality. In addition, we did not find evidence that laws were associated with differences in mortality rates for unrelated conditions (heart disease and septicemia), suggesting that differences in opioid analgesic overdose mortality cannot be explained by broader changes in health. In summary, although we found a lower mean annual rate of opioid analgesic mortality in states with medical cannabis laws, a direct causal link cannot be established."

"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."

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.

"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."

"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)."

"• 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."

"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."

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.

"The central finding gleaned from the present study was that MML [Medical Marijuana Legalization] 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 [Medical Marijuana Legalization], 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."

"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®."

"In conclusion, our results suggest that participation in the use of both licit and illicit drugs is price sensitive. Participation is sensitive to own prices and the price of the other drugs. In particular, we conclude that cannabis and cigarettes are complements, and there is some evidence to suggest that cannabis and alcohol are substitutes, although decriminalization of cannabis corresponds with higher alcohol use. Alcohol and cigarettes are found to be complements."

"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."

Click here for complete datatable of THC Potency of Tested Cannabis from Federal Seizure and State and Local Eradication Samples, by Type, 1985-2014.

"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 has to be assumed that they were representative of the market. Mean THC values are shown in Figure 16 for normal herbal cannabis, sinsemilla and resin. The anomalously high value for resin in 1997 (19.24 %) has been excluded; it was based on only five values and is over nine standard deviations above the mean potency for the period 1980–1996. Although there has been an increase in the 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 the potency of sinsemilla showed a 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 mean herbal cannabis THC levels in the ElSohly study were less than 2.4%. By contrast, and as shown in Figure 10, comparable levels at that 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. A recent analysis of cannabis seized in Florida in 2002 (Newell, 2003) showed amounts of THC found in samples ranging from 1.41% to 12.62%; the average THC content was 6.20%, which is almost identical to the 2002 value reported by the University of Mississippi Potency Monitoring Project."

"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."

"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)."

"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%)."

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."

"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."

Note: According to the DAWN report, "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)

"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."

"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."

"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 (26). Although the adjusted ORs <1 may be chance findings, they were observed for all non-reference exposure categories with all outcomes except oral cancer. Although purely speculative, it is possible that such inverse associations may reflect a protective effect of marijuana. There is recent evidence from cell culture systems and animal models that 9-tetrahydrocannabinol, the principal psychoactive ingredient in marijuana, and other cannabinoids may inhibit the growth of some tumors by modulating key signaling pathways leading to growth arrest and cell death, as well as by inhibiting tumor angiogenesis (27-29). These antitumoral associations have been observed for several types of malignancies including brain, prostate, thyroid, lung, and breast."

"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}"

"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."

"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."

"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."

"In summary, the notion that cannabis use itself is causally related to lower IQ and poorer educational performance was not supported in this large teenage sample. However, this study indeed has limitations, in particular the young age of outcome assessment. While we have demonstrated that confounding may be an explanation for links between cannabis use and poorer outcomes, large prospective cohorts tracking young people prior to, during and after stopping cannabis use, using more objective measures of drug use (e.g. the new NIH-funded ‘ABCD study’ in the United States; National Institute on Drug Abuse, 2015) are required before we can make strong conclusions. Cigarette smoking in particular has once again (Hooper et al., 2014; McCaffrey et al., 2010; Silins et al., 2014; Stiby et al., 2014) been highlighted as an important factor in adolescent outcomes, as well as a robust independent predictor of educational performance, and the reasons for this need to be elucidated."

"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."

"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."

"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."

"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."

"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."

"One of the major concerns about the psychological effects of chronic heavy cannabis use has been that it impairs adult 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). The evidential value of the field studies is limited by their small sample sizes, and the limited sociodemographic characteristics of their samples, while the evidential value of the laboratory studies is limited by the short periods of drug use, the youthful good health of the volunteers, and minimal demands made on volunteers in the laboratory (Cohen, 1982). Some regular cannabis users report a loss of ambition and impaired school and occupational performance as adverse effects of their use (e.g. Hendin et al, 1987) and that some ex-cannabis users give impaired occupational performance as a reason for stopping (Jones, 1984). Nonetheless, it is doubtful that cannabis use produces a well defined amotivational syndrome. It may be more parsimonious to regard the symptoms of impaired motivation as symptoms of chronic cannabis intoxication rather than inventing a new psychiatric syndrome."

"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)."

"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."

"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)"

"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)."

"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."

"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."

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."

"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."

"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)."

"... 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."

"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."

"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."

"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 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."

"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."

"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."