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1.1 Use

General Population

  • Cannabis is the most commonly used illicit drug in Ontario. One in ten (9.1%) adults (aged 15+) in Ontario (compared to 10.2% of adults Canada-wide) reported (past-year) cannabis use, according to the 2012 Canadian Alcohol and Drug Use Monitoring Survey (CADUMS), an annual representative survey of the Canadian adult population, including a sub-sample of 1,011 Ontarians.1
  • Among Ontario adults (aged 18+), 14. 5% reported cannabis use in the past year, and 45.3% had a lifetime history of cannabis use as per the Centre for Addiction and Mental Health (CAMH) Monitor, an annual representative cross-sectional survey of (n=5,013) Ontario adults in 2015. Cannabis use (past-year) rates among Ontario adults have increased steadily from 8.7% in 1996. In 2015, rates were higher among men (19.2%) than women (10.2%).2

Youth and Young Adults

  • Past year cannabis use was higher (37.9%) among young adults (ages 18-29) than older adults (8.3% among those 30+) in Ontario, and has doubled from 18.3% in 1996, according to the CAMH Monitor (n=5,013; 2015).2
  • One in five (21.3%) Ontario students (grades 7-12) used cannabis in the past year, and 23.9% used in their lifetime, based on the 2015 Ontario Student Drug Use and Health Survey (OSDUHS), a biennial representative cross-sectional survey of (n=10,426) Ontario public school students.3 Slightly fewer (16.1%) Ontario students (grade 7-12) reported cannabis use (past-year) in the 2014-15 Canadian Student Tobacco, Alcohol and Drugs Survey (CSTADS) (a biennial, nationally representative survey of public school students, including a sub-sample of 5,253 Ontario students); this was similar to the cannabis use rate (16.5%) reported by the entire Canadian sample (n=36,665).4
  • Past-year cannabis use among grade 7-12 students in Ontario has remained stable since 2011 (22.0%). Female (20.5%) and male (22.0%) students (grade 7-12) reported similar (past-year) cannabis use rates in 2015; rates increased steadily by grade from 10.3% among grade 10 students to 37.2% among grade 12 students. A minority (2.1%) of all students reported daily cannabis use. The majority (58.0%) of students (grade 9-12) found cannabis easy to obtain, with most (80.8%) obtaining it through a friend, as per the 2015 OSDUHS (n=10,426).3
  • One in three (33.0%) Ontario undergraduate students used cannabis in the past year and 17.5% did so in the past month, according to the 2004 Canadian Campus Survey, a national survey of Canadian undergraduates, including a random sub-sample of 2,107 students from 12 self-selected Ontario universities.5
  • 1.9% of postsecondary students in Ontario used cannabis daily, based on the National College Health Assessment (NCHA) which included a random sub-sample of 16,123 students from 16 self-selected Ontario postsecondary institutions in 2013 as part of a national study.6
  • Eight percent of high school students (grade 9-12) reported using an e-cigarette for marijuana, hash oil, liquid, or wax in the previous 12 months (n=3,171; OSDUHS).7
  • Between 1.6% and 2.0% of grade 10-12 students reported (past-year) use of synthetic cannabis (a variety of herbal mixtures that contain synthetic cannabinoid compounds). Past-year use did not change significantly between 2013 (1.8%) and 2015 (1.3%), according to the OSDUHS representative Ontario (n=10,426) student survey (2015).3

Special Populations

Indigenous Populations

  • One quarter (25.0%) of (n=1,500) Ontario First Nations adults (aged 18+) living on reserve used cannabis in the past-year. 35.3% of Ontario First Nations youth (n=600; aged 12-17) living on reserve reported past-year cannabis use, while 6.1% reported using cannabis daily or almost daily based on the 2008-10 cross-sectional representative Regional Health Survey of First Nations individuals living in 24 Ontario-based First Nations communities.8,9

Racialized Populations

  • Asian students in grades 7-12 in Ontario were significantly less likely than white students to have used cannabis in the past year (controlling for other demographic factors). Black/Afro-Caribbean students and students of other ethnicities did not differ from white students on cannabis use, according to data from the 2011 OSDUHS (n=9,288).10

Homeless and Street-Involved Populations

Medical Users

  • Among  a sample of Ontario-based users of cannabis for therapeutic purposes, 41% accessed therapeutic cannabis from a dispensary, 68% from a friend or someone they know, 29% from a dealer/on the street and 3% through Health Canada, based on a 2011-12 online convenience sample (n=242).15
  • The majority (57%) of Ontarians believed medical marijuana should be accessible by prescription rather than by permit, through a pharmacist, based on a legal age, or without restriction, according to an Ontario subsample of a nationally representative (n=3,824; 2016) online survey. Distribution through a pharmacy was chosen as the preferred method of distribution (53%), with most (75%) believing availability through a pharmacy would improve patient safety and oversight.16

Injection Drug Users

  • 75% of injection drug users (IDUs) reported cannabis use (past 6 month) in a convenience sample of (n=1,643) IDUs recruited from 26 select Ontario sites (2007) in the Ontario Harm Reduction Distribution Program Evaluation.17 75.2% of a sub-sample of (n=775) IDUs (aged 15+) from four sentinel  sites in Ontario (Thunder Bay, Sudbury, Toronto, Kingston) reported past 6 month marijuana use according to the I-Track cross-sectional national Canadian convenience sample of IDUs (2005-08).18

Recreational Drug Users

  • Past year cannabis use prevalence was 94% among a Health Canada study of 'recreational drug users' in Toronto recruited from event-specific sites such as raves or permanent nightclubs in Toronto (2012-13).13
  • Nearly three-quarters (73%) of a sample of youth involved in party scenes in Toronto used cannabis (past 6 months) based on the Toronto Youth Drug online survey (2014).13

Pregnant and Parenting Women

  • There is no publicly-available provincial data on women’s cannabis use during pregnancy.

1.2 Risks and Harms

Cannabis and Driving

  • Cannabis was the drug most frequently detected in toxicological testing of drivers involved in fatal motor vehicle collisions (MVCs) in Ontario, among (n=229) samples that were submitted for testing between 2011-12; drugs were detected in 44% of cases and cannabis was detected in 27% of those.19
  • Among all Ontario adults (aged 18+) with a driver's licence in 2015, 2.9% reported driving within 1 hour after using cannabis in the past year; this rate has been relatively stable since 2005. In 2015, almost all driving after cannabis use was reported by young adults (18-29 years), 7.5% of whom had done so in the past year, based on data from the 2015 CAMH Monitor (n=5,013).2
  • Ontario adults (aged 18+) who reported driving within 1 hour after cannabis use in the past year were more likely to have been involved in a collision (20.2%) than those who did not report driving after cannabis use (7.2%); this represents a greater collision risk than for those who reported driving after drinking in the past year (12.0%), according to CAMH Monitor data from 2002-07 (n=8,481).20 Those who reported both driving after cannabis use and after alcohol use in the past year were most likely to have been involved in a collision (30.5%) based on CAMH Monitor data from 2002-10 (n=16,224).21
  • In 2015, one in ten (9.8%) of all Ontario students (grades 10-12) with a driver's licence reported driving within 1 hour after using cannabis in the past year, a significant decrease since 2001 when the rate was one in five (19.9%); males (11.6%) were significantly more likely than females (7.6%) to use cannabis and drive according to the 2015 OSDUHS (n=10,426).3 
  • Two thirds (64.5%) of a (2005) convenience sample of (n=45) Toronto university students who had driven after cannabis use in the past year had done so within 1 hour. Most drove <10km (66.7%), had one or more passengers who had also used cannabis (71.1%), and had at least one episode when they decided against driving after cannabis use (51.1%).22

Morbidity and Mortality


  • In 2015, 7.5% of Ontario adults (aged 18+) met the criteria for moderate or high risk of cannabis problems in the past year based on the Cannabis Involvement Score from the Alcohol, Smoking and Substance Involvement Screening Test; this rate increased significantly from 4.7% in 2012, although moderate and high risk of cannabis problems have been generally stable from 2004-15, varying between 4.7% and 7.5%. In 2015, rates were high (18.2%) among young adults (18-29 years) and past-year cannabis users (45.1%) according to the CAMH Monitor (n=5,013).2
  • 1.2% of the general Ontario population (aged 15+) fulfilled the criteria for cannabis abuse or dependence in the past year, based on a sub-sample of 5,492 Ontarians in the 2012 Canadian Community Health Survey on Mental Health, a national cross-sectional survey representative of Canadian adults.23
  • 2.2% of Ontario students (grades 9-12) reported symptoms of cannabis dependence, measured by the Severity of Dependence Scale; this rate was 7.2% among past-year cannabis users (2015 OSDUHS, n=10,426).3

Burden of Disease

  • Hospital separations for people with a cannabis-related diagnosis in Ontario increased from 16/100,000 to 20/100,000 between 2000 and 2005, based on the Canadian Institute for Health Information's Hospital Morbidity Database of Canadian inpatient hospital separations (excluding psychiatric facilities, day procedure and emergency department visits).24

1.3 Interventions


  • Approximately one third (32.7%; 32,999 admissions) of patients presenting to publicly-funded substance abuse treatment reported cannabis as a problem substance in 2012-13. Cannabis was the most common problem drug (excluding alcohol and tobacco) at admission, and this rate has remained stable since 2007-08, based on data from the Drug and Alcohol Treatment Information System (DATIS), collected from over 170 publicly-funded substance abuse agencies across Ontario.25
  • Cannabis was the most common drug for which children and youth (0-24 years) were treated in Ontario between 2003 and 2012 (around 25/10,000 population). Treatment for cannabis use was most common among 15-19 year olds, males and children/youth living in the North East and North West Local Health Integration Networks (LHINs) in 2009-12, according to various data sources compiled into the Mental Health of Children and Youth in Ontario Baseline Scorecard report.26