Cannabis use in Canada: the need for a 'public health' approach.

Cannabis is the most commonly used illicit drug in Canada, used by 1 in 7 adults and 1 in 4 students. Other forms of drug use (e.g., alcohol or injection drug use) are increasingly approached within a public health policy framework that focuses on reducing harms rather than use per se. Cannabis, by contrast, remains formally controlled by a criminal justice approach that focuses on enforcing abstinence. Its use is associated with a variety of possible acute or chronic health problems that include cognitive and respiratory impairment, psychotic episodes, dependence and injury risk. The incidence of these outcomes, however, is predicted by early onset and a high frequency and length of use that only apply to a minority of users. In a public health framework, cannabis use - especially in young populations - should be systematically monitored and high-risk patterns of use screened for in appropriate settings, e.g., schools and GP offices. Evidence-based primary and secondary prevention, treatment and enforcement need to be targeted at these high-risk patterns of use. Given the large cannabis user population, especially among young people, and the failure of the criminalization approach to discourage use, a public health framework for cannabis use is urgently needed in Canada.