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Key points
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In October 2018, recreational cannabis use was legalized in Canada with the primary goals of improving public health and safety, restricting youth access, and reducing crime and illegal cannabis markets. of cannabis.
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Five years after legalization, available data suggest that most health-related outcomes, such as the prevalence of cannabis use, cannabis-related emergency department visits and hospitalizations, and driving under the influence of psychoactive substance, increased or remained stable.
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Data for some important health indicators are not available.
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A substantial reduction in arrests and criminal charges related to cannabis use among adults and youth, as well as related stigma and personal difficulties, should be considered a positive impact in terms of social justice, even as a indirect result in public health.
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Continuous measurement of key social and health outcomes as well as robust methods for integrating diverse data into the evaluation of policy outcomes are needed to inform evidence-based regulatory parameter changes that may be required to serve and achieve more effectively the public health objectives of the legalization of cannabis in Canada.
In October 2018, Canada was the first G-20 country to legalize the use and sale of cannabis for recreational purposes for adults . This legalization mainly aimed to improve public health and safety, restrict access for young people and fight against crime and illegal markets in cannabis, by authorizing and regulating the consumption of the psychoactive substance for adults as well as associated behaviors. Five years later, we examine whether these goals have been achieved, drawing on recent systematic reviews and primary studies 1 – 3 .
The legalization framework includes federal legislation (the Cannabis Act ) and related regulations, some of which have been clarified provincially. Key parameters for legal cannabis use and access include a possession limit of 30g of dried cannabis (or equivalent) in public by adults (at least 18–21 years of age, depending on the province ); consumption reserved for private environments (in most provinces); the progressive retailing of cannabis products in the form of cannabis flowers, extracts, liquids, and edibles; the use of private or public retail systems (or both, in some provinces) and the Internet; limited authorization of home cultivation (in most provinces); and national restrictions on driving under the influence of cannabis, based on laws establishing a “per se” limit on drugs.
National survey data comparing cannabis use before and after legalization showed an increased prevalence of use (from 22% in 2017 to 27% in 2022), with relative stability in rates of near-daily or daily use. (24%–25%) 4 . In contrast, a study of the adult population in Ontario found significant increases in the prevalence of use (adjusted odds ratio [OR] 1.62, 95% confidence interval [CI] 1.40– 1.86), daily consumption (adjusted OR 1.59, 95% CI 1.21–2.07) and consumption-related problems (adjusted OR 1.53, 95% CI 1.20– 1.95) between 2001 and 2019 5 . The prevalence of cannabis use among youth (30%–50%, depending on the survey) and the perception of access to cannabis by minors have changed little from high rates before legalization 1 , 4 .
Most studies have found an increase in cannabis-related emergency room visits and hospitalizations since legalization. For example, a time series analysis revealed a 20.0% (95% CI 6.2%–33.9%) increase in emergency department visits for cannabis-related disorders and poisonings among youth in Ontario and Alberta 6 . A population-based study in Ontario noted a 12%–22% increase in the number of adults who visited emergency departments between legalization and May 2021 7 . According to other studies conducted in this province, the monthly rate of emergency department visits for cannabinoid hyperemesis syndrome increased 13-fold (from 0.26 to 3.43 people per 100,000), the rate of emergency department visits emergency departments for cannabis-induced psychosis increased (incidence rate 1.30, 95% CI 1.02–1.66) and the number of acute care episodes during pregnancy involving cannabis increased almost doubled (from 11 to 20 people per 100,000), these variations being strongly associated with the commercialization phase in the province (from March 2020) 8 – 10 . According to a recent repeated cross-sectional study, the rate of emergency department visits related to cannabis poisoning among children (aged 0–9 years) almost tripled in 4 provinces in the year following legalization, and subsequently increased further in provinces that authorized the sale of edible products 11 .
At the same time, we observe a constant increase in the proportion of cannabis consumers using the legal market; most recently, data showed that approximately two-thirds obtain their cannabis from legal sources—50%–80%, depending on the type of cannabis product 1 , 12 . In contrast, the prevalence of cannabis-related impaired driving appears to have remained stable or decreased slightly. In British Columbia, the proportion of motorists hospitalized after a traffic accident testing positive for tetrahydrocannabinol (THC) increased after legalization (November 2018 to March 2020), with prevalence ratios adjusted for at pre-legalization rates (January 2013 to March 2018) ranging from 1.33 (95% CI 1.05–1.68) to 2.29 (95% CI 1.52–3.45) in 3 THC concentration levels in the blood 1 , 13 .
Several aspects of the evidence presented merit discussion. While some trends or variations in indicators clearly preceded legalization, the possibility that the results were a continuation of it has not been systematically assessed 1 , 5 . Additionally, the period following the legalization of cannabis in Canada was marked, to a large extent, by the COVID-19 pandemic, which may have influenced general trends and outcomes in psychoactive substance use, although these potential influences are equivocal 14 , 15 . There is a lack of pan-Canadian data on major outcome indicators, notably on cannabis use disorders and associated treatment demand, or on the correlation between the legalization of cannabis and the decline in alcohol and drug consumption. other psychoactive substances, as well as associated harms. Some trends in results could also be explained in part by regulatory differences between provinces and territories. For example, the lower prevalence and generally lower indicators in Quebec could reflect more restrictive regulations (public market monopoly, limited product range, ban on home cultivation, higher minimum legal purchasing age [21 years] ) 1 , 3 , 11 .
The available data, with appropriate caveats, present a mixed picture of changes in public health after legalization. If the evolution of certain key public health indicators suggests that legalization has had undesirable effects, other indicators have remained stable 1 – 3 . There is little evidence to support the expected improvement in public health and the health of cannabis users as part of the policy objectives. At this stage, the legalization of cannabis in Canada does not appear to have led to the public health disaster predicted by some of the opposition, although it cannot be described as a complete or unequivocal success for public health.
It is too early to draw conclusions on the impact of the legalization of cannabis in Canada that will clearly guide policy reforms. Authors of evaluations of cannabis legalization in the United States have also concluded that a 5-year period is too short to fully analyze the effects of such a significant policy change 16 . After decades of prohibition, the relative newness of legal cannabis, marketing efforts, and availability and regulation of the psychoactive substance as a consumer good could affect public attitudes and behavior 1 , 3 .
It is essential that overall assessments of policy impacts are not limited to health aspects. In addition to the substantial decline in the illegal supply of cannabis products, 1 , 13 legalization has had major and concrete social justice impacts. Thus, the number of cannabis-related offenses and arrests among adults (−74% among women and −83% among men, p < 0.001) and, to a lesser extent, among young people (−62% in girls and −53% in boys, p < 0.0001) fell between 2015 and 2021 17 , 18 . Prior to legalization, many cannabis-related criminal arrests were motivated by highly arbitrary or discriminatory (e.g., race-based) policing practices and focused on the circumstances of personal cannabis use 19 , 20 . Reducing interventions of this type has allowed tens of thousands of people to avoid receiving the criminal sanction and criminal record they would have received when recreational cannabis use was prohibited in Canada, as well as the stigma and other related personal difficulties (e.g., restrictions on employment, travel, social opportunities). These major societal benefits must be taken into account in any systematic assessment of the impact of policy reform. Unfortunately, methodological approaches for such comprehensive and integrated policy assessments, including the relative importance of health versus social outcomes, are underdeveloped.
The legalization of recreational cannabis in Canada is a controversial policy reform that has been closely followed within and outside the country’s borders. Review of evidence 5 years after implementation suggests that achievement of policy goals is mixed, with social justice benefits appearing more tangible than health benefits 1 – 3 , 17 , 18 . Therefore, it is essential to continue rigorously monitoring key policy outcome indicators, such as the prevalence of adult and youth use and high-risk drinking, the main health harms to short and long term (e.g., cannabis use disorders, injuries, cannabis-related hospitalizations or emergency department visits), as well as key social, criminal indicators (e.g., , regarding cannabis markets) and socio-economic. Robust methods for integrating diverse data into the evaluation of policy outcomes are also needed to guide evidence-based changes in regulatory parameters that may be required to more effectively serve and achieve the public health goals of the legalization of cannabis in Canada.
Footnotes
Competing interests: Benedikt Fischer reports receiving a grant from the Canadian Institutes of Health Research and having received a grant from the Substance Use and Addictions Program of Health Canada, where he served as a researcher (2021–2022) . Didier Jutras-Aswad states that he was paid as an expert witness by the Quebec government and received study materials from the company Cardiol Therapeutics for a study financed by public funds. He sits on the boards of directors of the Mental Health Commission of Canada, the Grand Chemin organization and the Fondation du CHUM. Wayne Hall states that he was paid as an expert witness by the Western Australian Police Service. No other competing interests have been declared.
This article has been peer-reviewed.
Contributors: Benedikt Fischer, Didier Jutras-Aswad and Wayne Hall jointly developed the concept for this article. Each author contributed substantially to the collection and interpretation of the data reviewed. Benedikt Fischer led the drafting of the preliminary version. All authors have critically revised its important intellectual content, given final approval for the version intended for publication, and take full responsibility for all aspects of the work.
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