CAMH Cannabis Policy Framework: Health Risks, Legalization, and Regulation

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Centre for Addiction and
Mental Health
1001 Queen St. West
Toronto, Ontario
Canada M6J 1H4
Tel: [phone]
www.camh.ca
A PAHO / WHO
Collaborating Centre
Fully affiliated with the
University of Toronto
CANNABIS POLICY FRAMEWORK
October 2014

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Table of contents
Executive summary ................................................................................................................. 1
What we know ........................................................................................................................ 2
Cannabis is the most commonly used illegal drug in Canada..................................................... 2
Cannabis use carries health risks ................................................................................................ 3
Cannabis‐related harm is concentrated among a limited group of high‐risk users ................... 5
Criminalization of cannabis use causes additional harms, without dissuading it ...................... 6
Legal reform of cannabis control is needed ............................................................................... 7
Why legalize and regulate?...................................................................................................... 8
Decriminalization: a half measure .............................................................................................. 9
Legalization: an opportunity for evidence‐based regulation ................................................... 11
Moving from prohibition to regulation ....................................................................................... 12
Principles to guide health‐focused cannabis control................................................................ 12
Potential risks, and how to mitigate them ............................................................................... 13
Conclusion ............................................................................................................................. 16
About CAMH ......................................................................................................................... 17
References............................................................................................................................. 18

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Executive summary
Cannabis is a favourite recreational drug of Canadians, along with alcohol and tobacco. Like
those drugs, cannabis (popularly known as marijuana) is associated with a variety of health
harms. Unlike those drugs, cannabis is illegal, prohibited under the same federal and
international drug statutes as heroin and cocaine.
The landscape of cannabis policy is changing. The Netherlands, Portugal, and more recently
Uruguay and US states Colorado and Washington have reformed their approach to cannabis
control. Here in Canada, changes to the rules of the federal Medical Use of Marijuana program
are expected to lead to an increase in the number of registered users over the next few years.
Public support for reform of Canada’s cannabis laws continues to grow. Meanwhile, we
continue to improve our understanding of the health risks of cannabis use.
As Canada’s leading hospital for mental illness, the Centre for Addiction and Mental Health
(CAMH) offers evidence‐based conclusions about cannabis and measures aimed at reducing
harm. CAMH has reviewed the evidence on cannabis control and drawn the following
conclusions:
 Cannabis use carries significant health risks, especially for people who use it frequently
and/or begin to use it at an early age.
 Criminalization heightens these health harms and causes social harms.
 A public health approach focused on high‐risk users and practices – similar to the
approach favoured with alcohol and tobacco – allows for more control over the risk
factors associated with cannabis‐related harm.
From these conclusions follows another:
 Legalization, combined with strict health‐focused regulation, provides an opportunity to
reduce the harms associated with cannabis use.
This approach is not without risks. A legal and unregulated or under‐regulated approach may
lead to an increase in cannabis use. Finding the right balance of regulations and effectively
implementing and enforcing them is the key to ensuring that a legalization approach results in a
net benefit to public health and safety while protecting those who are vulnerable to cannabis‐
related harms.
CAMH neither makes a moral statement on cannabis nor encourages its use. Despite the
prohibition of cannabis, more than one third of young adults are users, and our current
approach exacerbates the harms. It’s time to reconsider our approach to cannabis control.

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What we know
Cannabis is the most commonly used illegal drug in Canada
Canada has one of the highest rates of cannabis use in the world. More than 40% of Canadians
have used cannabis in their lifetime and about 10% have used it in the past year.1 No other
illegal drug is used by more than 1% of Canadians every year.2
Population surveys in Ontario 3 indicate that 14% of adults and 23% of high school students used
cannabis in 2013. As shown in the table below, men are nearly 50% more likely to be past‐year
users than women. Cannabis use is most common among adolescents and young adults, but
half of the province’s users are age 30 or older. Between 1997 and 2005, cannabis use among
adults trended upward – particularly among 18 to 29 year‐olds – but has levelled off since then.
Among high school students there has been a steady and significant decrease in past‐year use
since 2003.
CANNABIS USE IN ONTARIO: percentage of the population using cannabis in the past year4
1997 2001 2005 2009 2013
General population (age 18+) 9.1 11.2 14.4 13.3 14.1
By gender
 Men 11.4 15.4 18.8 17.4 17.6
 Women 7.0 7.3 10.3 9.5 10.8
By age
 Grades 7‐12 28.0* 28.6 26.5 25.6 23.0
 Age 18‐29 21.4 26.8 38.2 35.8 40.4
 Age 30‐39 9.8 15.8 16.9 12.9 17.3
 Age 40‐49 4.3 7.2 10.8 11.7 8.4
 Age 50+ 1.7 3.3 2.6 4.7 5.9
* figure from 1999
1 Health Canada, 2013
2 Health Canada, 2013
3 Ialomiteanu et al., 2012; Ialomiteanu et al., 2014; Boak et al., 2013
4 All data Ialomiteanu et al., 2012, except Grades 7‐12 (Boak et al., 2013) and general population data for 2013 (Ialomiteanu et al., 2014)

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60% of past‐year adult cannabis users in Ontario use it at least once a month, 5 and about 27%,
or nearly 4% of the total adult population, use it every day.6 From other jurisdictions we know
that a small proportion of cannabis users is responsible for the bulk of consumption; it is
estimated that 20% of users account for 80‐90% of consumption. 7
Most people who use cannabis do not use other illegal drugs, and cannabis use alone does not
increase the likelihood that a person will progress to using other illegal substances.8
Public opinion on cannabis control has shifted considerably in the past decade. Ten years ago
about half of Canadians believed cannabis use should be decriminalized or legalized; today,
about two thirds of Canadians hold this view. 9
Cannabis use carries health risks
Cannabis is not a benign substance. Its health harms increase with intensity of use. Particularly
when used frequently (daily or near‐daily), cannabis is associated with increased risk of
problems with cognitive and psychomotor functioning, respiratory problems, dependence, and
mental health problems.
Problems with cognitive and psychomotor functioning
Cannabis use is known to negatively affect memory, attention span, and psychomotor
performance. Frequent use may reduce motivation and learning performance, and work or
study can be negatively affected as a result.10 In adults, these changes are not generally
permanent; effects usually dissipate several weeks after use is discontinued.
Most significant from a public health perspective is the impact of cannabis use on the skills
necessary for safe driving and the substantial increase of risk of motor‐vehicle accidents.11 In
Ontario, an estimated 9% of licensed drivers aged 18 to 29 and 10% of those in grades 10 to 12
report having driven within an hour of using cannabis in the past year.12 Rates of cannabis‐
impaired driving exceed rates of alcohol‐impaired driving for both age groups. Although the
accident risk associated with cannabis‐impaired driving is significantly lower than that of
alcohol‐impaired driving, it is a serious concern: motor‐vehicle accidents due to impaired
driving are the main contribution of cannabis to Canada’s burden of disease and injury.
5 Ialomiteanu et al., 2014
6 Health Canada, 2013
7 Room et al., 2010
8 Room et al., 2010
9 National Post, 2013; Ottawa Citizen, 2014
10 Block et al., 2002; Pope et al., 1996
11 Hartman and Huestis, 2013; Hall and Degenhardt, 2009
12 Ialomiteanu et al., 2012; Boak et al., 2013

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Respiratory problems
Like tobacco, cannabis smoke contains tar and other known cancer‐causing agents. Regular,
long‐term cannabis smoking is linked to bronchitis and cancer.13 Cannabis smokers often hold
unfiltered smoke in their lungs for maximum effect, which adds to these risks. About half of
past‐year users also smoke tobacco and it is likely that tobacco smoking contributes greatly to –
or is the primary cause of – many of these respiratory problems.14
Dependence
About 9% of cannabis users develop dependence. 15 People who develop cannabis dependence
may have difficulty quitting or cutting down and may persist in using it despite negative
consequences; those who stop suddenly may experience mild withdrawal symptoms including
irritability, anxiety, upset stomach, loss of appetite, disturbed sleep, and depression. 16 Long‐
term frequent users have a higher risk of dependence than occasional users. By way of
comparison, the estimated probability of developing dependence is 68% for nicotine, 23% for
alcohol, and 21% for cocaine.17
Mental health problems
Frequent cannabis use has been found by many studies to be associated with mental illness. 18 It
is thought to increase the likelihood of mental illness in people with a pre‐existing vulnerability
to it and to exacerbate symptoms in people already experiencing mental illness. 19 Even
occasional use can increase these risks: it has been estimated that cannabis users have a 40%
higher risk of psychosis than non‐users.20 Frequent users have an even higher risk – 50% to
200% higher than non‐users – indicating a possible dose response. High‐potency cannabis –
that is, cannabis with a high concentration of tetrahydrocannabinol (THC), the main
psychoactive component of cannabis – places users at higher risk of mental health problems
than low‐potency cannabis. 21 This association between cannabis use and mental illness is
robust but not yet well understood. Causality has not been determined.22
13 Tetrault et al., 2007
14 Fischer et al., 2011
15 Lopez‐Quintero et al., 2011
16 Anthony, 2006; Kalant, 2004
17 Lopez‐Quintero et al., 2011
18 For a summary see Volkow et al., 2014, and Fischer et al., 2011.
19 McLaren et al., 2009; Hall et al., 2004
20 Moore et al., 2007
21 Di Forti et al., 2009
22 McLaren et al., 2009