Prime Minister Trudeau and the Liberal government have indicated that they intend to legalize marijuana usage. Canadians need to take a hard look at the facts and carefully consider whether this is the right direction to go.  The evidence indicates there are many reasons to be concerned about taking this road.

Click on the titles below for quotations from experts on the following:

A recently published study provides the strongest epidemiological evidence to date that smoked cannabis is a risk factor for lung cancer. In this 40-year retrospective cohort study of 50,000 Swedish male conscripts, regular cannabis smoking was associated with a 2-fold risk of lung cancer, even after controlling for tobacco use and other factors (42). Smoking also creates byproducts that are atherogenic and may precipitate angina or myocardial infarction.

Kalant H. Marihuana: Medicine, addictive substance, or both? A common-sense approach to the place of cannabis in medicine. Canadian Journal of Addiction Medicine 2013;4(3):p14.

Marijuana use has many serious, negative health effects which are of deep concern to the ASAM.

American Society of Addiction Medicine (ASAM). (2012). White Paper on State-Level Proposals to Legalize Marijuana. Retrieved from http://www.asam.org/docs/publicy-policy-statements/state-level-proposals-to-legalize-marijuana-final2773DD668C2D.pdf. Accessed 2016 Aug 24.

Despite emerging scientific evidence on the adverse health risks of marijuana smoke, many people think that marijuana smoke is less toxic than tobacco smoke. Marijuana smoke contains chemicals (e.g., polycyclic aromatic hydrocarbons, carbon monoxide, cyanide, benzene) known to cause cancer and reproductive toxicity, many of which are also in tobacco smoke. Indeed, except for the psychoactive ingredient —THC versus nicotine —marijuana smoke is similar to tobacco smoke. This similarity makes it likely that marijuana use will have comparable health effects as tobacco, a prediction supported by recent findings that marijuana and tobacco secondhand smoke exposure both have adverse cardiovascular effects. For example, combustible marijuana use and secondhand marijuana smoke exposure significantly impair blood vessel function, similar to tobacco, in ways that would increase the risk of atherosclerosis (partially blocked arteries), heart attack, and stroke.

Marijuana smokers are also at an increased risk of respiratory problems including chronic bronchitis, as marijuana smoke is associated with inflammation of the large airways, increased airway resistance, and lung hyperinflation. Marijuana smokers also report increased rates of respiratory infections and pneumonia compared to nonsmokers.

Increased marijuana use may produce other adverse effects such as long-lasting detrimental changes in brain function in adolescents, increased risk for addiction (especially when initiated in adolescence), and elevated risks of mental health disorders (e.g., anxiety, mood, and psychotic). Increased marijuana use also may result in increased traffic accidents from driving while impaired by marijuana.

Barry, Rachel A MA; & Glantz, Stanton A PhD. (2016). A Public Health Analysis of Two Proposed Marijuana Legalization Initiatives for the 2016 California Ballot: Creating the New Tobacco Industry. UC San Francisco: Center for Tobacco Control Research and Education. Page 9.

In this new study, researchers compared marijuana smoke to tobacco smoke, using smoking machines to simulate the smoking habits of users. The scientists found that ammonia levels were 20 times higher in the marijuana smoke than in the tobacco smoke, while hydrogen cyanide, nitric oxide and certain aromatic amines occurred at levels 3-5 times higher in the marijuana smoke, they say. The finding is “important information for public health and communication of the risk related to exposure to such materials,” say the researchers.

American Chemical Society. “Marijuana Smoke Contains Higher Levels Of Certain Toxins Than Tobacco Smoke.” ScienceDaily. ScienceDaily, 18 December 2007. 

Researchers find that the mean age of marijuana-smoking patients with lung problems was 41, as opposed to the average age of 65 years for tobacco-smoking patients.

“Marijuana is inhaled as extremely hot fumes to the peak inspiration and held for as long as possible before slow exhalation. This predisposes to greater damage to the lungs and makes marijuana smokers are more prone to bullous disease as compared to cigarette smokers.”

Patients who smoke marijuana inhale more and hold their breath four times longer than cigarette smokers. It is the breathing manoeuvres of marijuana smokers that serve to increase the concentration and pulmonary deposition of inhaled particulate matter – resulting in greater and more rapid lung destruction.

Blackwell Publishing. “Marijuana Smokers Face Rapid Lung Destruction — As Much As 20 Years Ahead Of Tobacco Smokers.” ScienceDaily. ScienceDaily, 27 January 2008. 

The harmful effects have in the past been studied and documented more thoroughly than the therapeutically useful ones. Probably most physicians are aware of the impairment of learning, memory, alertness, reaction speed and judgment that are characteristic of acute intoxication with cannabis, and that result in impairment of school and work performance and of operation of aircraft and motor vehicles. Less well known is the inhibitory effect of chronic cannabis exposure on the maturation of neuronal pathways in the fetus and in childhood and early adolescence, with resulting mild but long-lasting impairment of so-called executive functions such as problem solving, comparative evaluation of alternative options, and working memory. Chronic smoking of cannabis, as distinct from the actions of cannabinoids per se, is also known to give rise to chronic inflammatory changes in the airways, with chronic cough and wheezing, and precancerous histological changes in the bronchial epithelium.

Kalant H. Marihuana: Medicine, addictive substance, or both? A common-sense approach to the place of cannabis in medicine. Canadian Journal of Addiction Medicine 2013;4(3):p5.

Persistent marijuana use before adulthood may permanently impair cognitive functioning (Solowij et al, 2002; Meier et al, 2012) and confer a higher risk of developing psychiatric diseases, such as schizophrenia, in susceptible individuals (Arseneault et al, 2004). Chronic adolescent, but not adult, cannabinoid exposure produces lasting working memory impairments and recapitulates other schizophrenia endophenotypes in rodents, including impaired sensorimotor gating, social avoidance, and anhedonia/avolition (Schneider and Koch, 2003; O’Shea et al, 2004; Quinn et al, 2008). (page 2338)

Adolescents are especially sensitive to repeated marijuana use, presumably because marijuana interferes with ongoing anatomical and physiological maturation of the brain, particularly the cerebral cortex (Andersen, 2003).  (page 2338)

Impairments in working memory, processing speed, perceptual reasoning, and other executive functions have been documented in long-term adolescent cannabis users (Solowij et al, 2002; Meier et al 2012). Poor cognitive performance in persistent marijuana users may be related to the cortical oscillation attenuation that we report, as synchronous cortical neural activity plays a role in selective attention (Fries et al, 2001), integration of sensory information (Singer and Gray, 1995), working memory (Roux et al, 2012), and other cognitive functions (Buzsaki, 2006; Wang, 2010). Chronic adolescent, but not adult, cannabinoid-induced oscillation suppression suggests that attenuated network synchrony is not merely a consequence of repeated cannabinoid exposure, but reflects a unique sensitivity of the adolescent brain to modification by cannabinoids. Our data are consistent with findings that adolescent, but not adult, cannabinoid exposure produces lasting cognitive impairments in rodents (Schneider and Koch, 2003; O’Shea et al, 2004; Quinn et al, 2008) and humans (Solowij et al, 2002; Meier et al, 2012). (page 2345)

Sylvina M Raver, Sarah P Haughwout and Asaf Keller, ‘Adolescent Cannabinoid Exposure Permanently Suppresses Cortical Oscillations in Adult Mice’, Neuropsychopharmacology July 4th 2013, doi:10.1038/npp.2013.164
  • THC exposure during adolescence induces long-term deficits in social motivation.
  • Both adolescent and adulthood THC exposure induces deficits in social cognition/memory.
  • Adolescent THC exposure induces long-term deficits in exploratory behaviors
  • THC exposure during adolescence induces long-term increases in anxiety measures
  • Adolescent THC exposure induces long-term deficits in sensorimotor gating

The present study demonstrates that exposure to chronic THC during a specific window of adolescent neurodevelopment can induce enduring neuropsychiatric-like behavioral, molecular, and neuronal phenotypes, at the cortical and sub-cortical levels.

…chronic THC exposure specifically during adolescence leads to deficits in social motivation, consistent with clinical studies showing that heavy adolescent cannabis use is associated with a persistent “amotivational syndrome” principally defined by lethargy, inactivity, and social withdrawal.

In summary, consistent with a growing body of clinical evidence, the present findings demonstrate that adolescence represents a selective neurodevelopmental window of vulnerability wherein the developing brain is particularly sensitive to the effects of chronic THC exposure. Given the exponential global rise in cannabis use for both recreational and therapeutic purposes, these findings have critical implications for public health policy development related to regulating adolescent versus adulthood exposure to cannabis.

Justine Renard, Laura G. Rosen, Michael Loureiro, Cleusa De Oliveira, Susanne Schmid, Walter J. Rushlow, and Steven R. Laviolette. Adolescent Cannabinoid Exposure Induces a Persistent Sub-Cortical Hyper-Dopaminergic State and Associated Molecular Adaptations in the Prefrontal Cortex Cereb. Cerebral Cortex first published online January 4, 2016 doi:10.1093/cercor/bhv335

Consistent and heavy marijuana use by teens also may have rather severe long-term impacts by impairing cognitive functioning and brain development.

Sen, Anindya, Joint Venture: A Blueprint for Federal and Provincial Marijuana Policy (April 20, 2016). C.D. Howe Institute ebrief 235 (2016). Available at SSRN: http://ssrn.com/abstract=2768975

Historical drug trends from the national Monitoring the Future Survey show that when anti-drug attitudes soften there is a corresponding increase in drug use in the coming years. An adolescent’s perception of risks associated with substance abuse is an important determinant of whether he or she engages in substance abuse. Youths who perceive high risk of harm are less likely to use drugs than youths who perceive low risk of harm.

“The DEA Position on Marijuana.” U.S Drug Enforcement Administration. United States Department of Justice, April 2013. Web. 25 Aug. 2016. 

Canadian youth has the highest rate of marijuana use among developed countries, with almost a quarter of the population aged 15 to 24 years reporting past-year use.

Hajizadeh, Mohammad. “Legalizing and Regulating Marijuana in Canada: Review of Potential Economic, Social, and Health Impacts.” International Journal of Health Policy and Management 5.8 (2016): 453–456. PMC. Web. 24 Aug. 2016.

The RAND Corporation analyzed the prospective effects of legalized marijuana under passage of California’s Proposition 19 in 2010 with the continued federal prohibition of marijuana. Researchers concluded that rates of marijuana use in that state would substantially increase.

American Society of Addiction Medicine. White Paper on State-Level Proposals to Legalize Marijuana. Page 8.

This study has shown consistently over decades that when the perception of harm from marijuana use was high, marijuana use was low and when the perception of harm from marijuana use was low, the use was high.

American Society of Addiction Medicine. White Paper on State-Level Proposals to Legalize Marijuana. Page 13.

In California tobacco is legal, but its use is increasingly denormalized, while marijuana is illegal but becoming more socially accepted. This reality is reflected by the fact that, in California, more youth are now using marijuana than tobacco.

Barry, Rachel A MA; & Glantz, Stanton A PhD. (2016). A Public Health Analysis of Two Proposed Marijuana Legalization Initiatives for the 2016 California Ballot: Creating the New Tobacco Industry. UC San Francisco: Center for Tobacco Control Research and Education. Page 10.

Not only has the use of drugs in certain contexts increased, but socio-cultural attitudes regarding use, they argue, have shifted “from the margins toward the center of youth culture” [(1), p. 152]. The use of marijuana in particular no longer can be described as marginal or deviant in the sense of denoting membership in a distinctive subculture.

Cannabis is the most widely used illicit drug in western nations. Estimates in Canada suggest that almost half of the population over age 15 has used cannabis at least once, and more than half of university undergraduate students. Starting in the 1990s, Adlaf and his colleagues have documented increasing prevalence and incidence of use in all age cohorts, with estimated lifetime use among Canadians increasing from23% in 1989, to 28% in 1994, to 44% in 2004.With respect to prevalence, lifetime use alone may be less indicative of normalization than increases in recent or regular use. Studies in the UK suggest that 10–15% of late adolescents are recent, regular recreational cannabis users, with this proportion rising to 20–25% among young adults. Similarly, young Canadians are not only more likely than the previous generation to have used the drug in their life time; they are more likely to have done so within the past 12 months. About 70% of those from 18 to 24 years old reported using cannabis at least once. And nearly half of those between 18 and 19 reported use in the past-year, a number that has doubled since 1994. Marijuana use is therefore common among students, and most say they find it “easy” or “very easy” to obtain.

Mostaghim, Amir, and Andrew D. Hathaway. “Identity Formation, Marijuana and ‘The Self’: A Study of Cannabis Normalization among University Students.” Frontiers in Psychiatry 4 (2013): 160. PMC. Web. 16 Aug. 2016. Page 1.

Marijuana (MJ) is the most commonly used illicit drug by adolescents. Indeed, chronic MJ use among teens is occurring at earlier ages and with increasing global prevalence. (Page 1)

Justine Renard, Laura G. Rosen, Michael Loureiro, Cleusa De Oliveira, Susanne Schmid, Walter J. Rushlow, and Steven R. Laviolette. Adolescent Cannabinoid Exposure Induces a Persistent Sub-Cortical Hyper-Dopaminergic State and Associated Molecular Adaptations in the Prefrontal Cortex Cereb. Cerebral Cortex first published online January 4, 2016 doi:10.1093/cercor/bhv335

As public perception of marijuana’s safety has grown, some states have also passed voter-approved referenda legalizing recreational use of marijuana by adults. The result has been the same: limited legalization has led to greater availability of marijuana to youth.

A substantial concern about legalization of adult marijuana is that it will result in an increase in adolescent use, a group that appears to be most vulnerable to its harmful effects.

There is evidence legalization of marijuana limited to medical dispensaries and/or adult recreational use has led to increased unintended exposure to marijuana among young children. By 2011, rates of poison center calls for accidental pediatric marijuana ingestion more than tripled in states that decriminalized marijuana before 2005. In states which passed legislation between 2005 and 2011 call rates increased nearly 11.5% per year. There was no similar increase in states that had not decriminalized marijuana as of December 31, 2011. Additionally, exposures in decriminalized states where marijuana use was legalized were more likely than those in non-legal states to present with moderate to severe symptoms requiring admission to a pediatric intensive care unit. The median age of children involved was 18-24 months.

Marijuana use by adolescents has grown steadily as more states enact various decriminalization laws. According to CDC data, more teens now smoke marijuana than cigarettes.

After a period of decline in the last decade, marijuana use has generally increased among young people since 2007, corresponding with both its increased availability through limited legalization and a diminishing perception of the drug’s risks. The number of current (past month) users aged 12 and up increased from 14.5 to 18.9 million.

In 2010, 7.3 percent of all persons admitted to publicly funded treatment facilities were aged 12-17. Marijuana is the leading illicit substance mentioned in adolescent emergency department admissions and autopsy reports, and is considered one of the major contributing factors leading to violent deaths and accidents among adolescents.

The Legalization of Marijuana in Colorado: The Impact” is a compilation of data by the Rocky Mountain High Intensity Drug Trafficking Area that analyzes the effects of marijuana legalization in the state. This third volume allows readers to compare and contrast statistics observed from 2006 – 2009 during Colorado’s early medical marijuana era with those from 2009 to 2013 as medical marijuana commercialization grew, and also with those from the current legalized recreational marijuana era from 2013 to the present. The statistics reveal that between 2013 and 2014 there was a 45% increase in marijuana-associated impaired driving, a 32% increase in marijuana-related motor vehicle deaths (with a 92% increase from 2010 to 2014), as well as 29% and 38% increases in emergency room visits and hospital admissions secondary to marijuana use. By 2013, marijuana use in Colorado was 55% above the national average among teens and young adults, and 86% higher among those over age 25.

Anderson, Jane, MD, FCP, and Donald Hagler, MD, FCP. “Marijuana Use: Detrimental to Youth.” American College of Pediatricians. N.p., 29 Apr. 2016. Web. 23 Aug. 2016.

[A manuscript]… using data from the National Household Survey on Drug Use that also examined data up to 2011 reported a significant decrease in adolescent perceptions of marijuana risk in Colorado compared to non-medical marijuana states as well as a significantly higher adolescent marijuana/abuse dependence prevalence after widespread adult medical legalization. A number of reports suggest substantial diversion of medical marijuana to adolescents as well as increases of marijuana overdoses in young children as well as a significant increase in the proportion of marijuana-positive drivers involved in traffic fatalities in Colorado compared to non-medical marijuana states.

A substantial concern about legalization of adult marijuana use is that it will result in an increase in adolescent use, a group that appears to be most vulnerable to its harmful effects.

Hopfer, Christian. “Implications of Marijuana Legalization for Adolescent Substance Use.” Substance abuse : official publication of the Association for Medical Education and Research in Substance Abuse 35.4 (2014): 331–335.PMC. Web. 23 Aug. 2016.

But the arguments for legalization often overlook its considerable downsides and risks. They serially underplay, for instance, the possibility of substantially increased use of dependence on drugs.

Caulkins, Jonathan P. and Michael A.C. Lee.  2012.  “The Drug-Policy Roulette.”  National Affairs.  12, p.36.

Legalizing drugs is like toasting bread: Not all of the resulting changes can be undone by re-imposing prohibition. Pre-legalization conditions will be gone forever… Social norms, too, would change, making drug use a more accepted part of daily life (what sociologists call “banalization”).

Caulkins, Jonathan P. and Michael A.C. Lee.  2012.  “The Drug-Policy Roulette.”  National Affairs.  12, p.40.

Claims that marijuana has medicinal benefits create additional challenges for adolescent prevention efforts as they contrast with messages of harmfulness.

Hopfer, Christian. “Implications of Marijuana Legalization for Adolescent Substance Use.” Substance abuse : official publication of the Association for Medical Education and Research in Substance Abuse 35.4 (2014): 331–335.PMC. Web. 23 Aug. 2016.

A federal bill to legalize marijuana would make Canada the first developed country to legalize marijuana in the world.

Hajizadeh, Mohammad. “Legalizing and Regulating Marijuana in Canada: Review of Potential Economic, Social, and Health Impacts.” International Journal of Health Policy and Management 5.8 (2016): 453–456. p.454. PMC. Web. 24 Aug. 2016.

Youth past month marijuana use increased 20 percent in the two year average (2013/2014) since Colorado legalized recreational marijuana compared to the two-year average prior to legalization (2011/2012). Nationally youth past month marijuana use declined 4 percent during the same time.

The latest 2013/2014 results show Colorado youth ranked #1 in the nation for past month marijuana use, up from #4 in 2011/2012 and #14 in 2005/2006. Colorado youth past month marijuana use for 2013/2014 was 74 percent higher than the national average compared to 39 percent higher in 2011/2012.

Adult past-month marijuana use increased 63 percent in the two year average (2013/2014) since Colorado legalized recreational marijuana compared to the two-year average prior to legalization (2011/2012). Nationally adult past month marijuana use increased 21 percent during
the same time.

The latest 2013/2014 results show Colorado adults ranked #1 in the nation for past month marijuana use, up from #7 in 2011/2012 and #8 in 2005/2006.

Rocky Mountain High Intensity Drug Trafficking Area. 2016. “The Legalization of Marijuana in Colorado: The Impact. Volume 4.” 

Marijuana-related traffic deaths increased 48 percent in the three-year average (2013-2015) since Colorado legalized recreational marijuana compared to the three-year average (2010-2012) prior to legalization.

In 2009, Colorado marijuana-related traffic deaths involving operators testing positive for marijuana represented 10 percent of all traffic fatalities. By 2015, that number doubled to 21 percent.

Rocky Mountain High Intensity Drug Trafficking Area. 2016. “The Legalization of Marijuana in Colorado: The Impact. Volume 4.” 

Currently, marijuana is the most common drug involved in drugged driving – a significant cause of highway crashes, injury, and death.  New research from meta-analyses shows that marijuana use doubles the risk of a car crash; habitual marijuana use is associated with increased risk of crash injury.

Thus, decreases in highway safety constitute an easy-to-predict negative consequence of the legalization of marijuana by adults.

American Society of Addiction Medicine (ASAM). (2012). White Paper on State-Level Proposals to Legalize Marijuana. Retrieved from http://www.asam.org/advocacy/find-a-policy-statement/view-policy-statement/public-policy-statements/2014/07/24/white-paper-on-state-level-proposals-to-legalize-marijuana. Accessed 2016 Aug 24. 

ASAM asserts that the anticipated public health costs of marijuana legalization are significant and are not sufficiently appreciated by the general public or by public policy makers.

American Society of Addiction Medicine (ASAM). (2012). White Paper on State-Level Proposals to Legalize Marijuana. Retrieved from http://www.asam.org/advocacy/find-a-policy-statement/view-policy-statement/public-policy-statements/2014/07/24/white-paper-on-state-level-proposals-to-legalize-marijuana. Accessed 2016 Aug 24. 

Seminal reviews concluded that, based on relevant cognitive, memory/reaction and psychomotor ability impairments, drivers under the influence of cannabis have a two to three times elevated risk of being involved in (fatal or non-fatal) MVA.

While concrete data for Canada are still limited, it can thus be estimated that 4–12% of MVA-related fatalities and/or injuries may involve driving under the influence of cannabis. There were 2227 MVA-related fatalities and 170 629 injuries (all) in Canada in 2010. On this basis, there may be 89–267 cannabis-related MVA fatalities, and 6825–20 475 cannabis-related MVA injuries in 2010.

Fischer B, Imtiaz S, Rudzinski K, Rehm J. “Crude estimates of cannabis-attributable mortality and morbidity in Canada-implications for public health focused intervention priorities.” J Public Health (Oxf). 2016; 38(1):183-188. doi:10.1093/pubmed/fdv005

…full legalization and commercialization may substantially reduce the eventual price of marijuana. Adolescents may be particularly influenced by eventual price reductions as they typically have more limited financial  means and may be a primary target of black market sales.

Hopfer, Christian. “Implications of Marijuana Legalization for Adolescent Substance Use.” Substance abuse : official publication of the Association for Medical Education and Research in Substance Abuse 35.4 (2014): 331–335.PMC. Web. 23 Aug. 2016.

What makes illegal drugs so expensive is precisely the fact that their production is prohibited, and that this prohibition is often strictly enforced.

Caulkins, Jonathan P. and Michael A.C. Lee.  2012.  “The Drug-Policy Roulette.”  National Affairs.  12, p.37.

And a wide range of indicators of drug use—including treatment admissions, emergency-department mentions, ambulance call-outs, and urine  tests  of arrestees—are negatively correlated over time with price movements, meaning they decline when prices go up.

Observing historical correlation is of course insufficient to establish a causal relationship. But in a pioneering econometric study conducted in the late 1970s, Lester Silverman and Nancy Spruill estimated that a 50% increase in the price of heroin would reduce heroin consumption by 13%. And over the past 35 years, a large and increasingly international body of literature has replicated Silverman and Spruill’s general finding.

Caulkins, Jonathan P. and Michael A.C. Lee.  2012.  “The Drug-Policy Roulette.”  National Affairs.  12, p.40.

Advocates claim that legalizing drugs would bring a host of benefits—erasing the problems of prison  overcrowding, drug-related crime and violence, corruption, overdose deaths, and the spread of blood-borne diseases (principally HIV/AIDS and Hepatitis C). But there is an irony in this agenda that should not be overlooked: The only major illegal drug with any realistic prospect of being legalized in the United States is marijuana—and legalizing marijuana would not materially reduce any of these problems.

Caulkins, Jonathan P. and Michael A.C. Lee.  2012.  “The Drug-Policy Roulette.”  National Affairs.  12, p.48.

Drug use and distribution do drive a great deal of non-drug crim, but the real culprits are the “expensive majors”—heroin, cocaine and crack, and meth—not marijuana. One rarely hears of drive-by shootings between rival marijuana gangs…

Caulkins, Jonathan P. and Michael A.C. Lee.  2012.  “The Drug-Policy Roulette.”  National Affairs.  12, p.49.

If you wonder why America is in the grips of a heroin epidemic that kills two hundred people a week, take a hard look at the legalization of pot, which destroyed the profits of the Mexican cartels. How did they respond to a major loss in revenue? Like any company, they created an irresistible new product and flooded the market.

Winslow, Don. “El Chapo and the Secret History of the Heroin Crisis.” Esquire. N.p., 2016. Web. 24 Aug. 2016. http://www.esquire.com/news-politics/a46918/heroin-mexico-el-chapo-cartels-don-winslow/