Assessing the public health impacts of legalizing recreational cannabis use: the US experience

Abstract

The sale of cannabis for adult recreational use has been made legal in nine US states since 2012, and nationally in Uruguay in 2013 and Canada in 2018. We review US research on the effects of legalization on cannabis use among adults and adolescents and on cannabis‐related harms; the impact of legalizing adult recreational use on cannabis price, availability, potency and use; and regulatory policies that may increase or limit adverse effects of legalization. The legalization of recreational cannabis use in the US has substantially reduced the price of cannabis, increased its potency, and made cannabis more available to adult users. It appears to have increased the frequency of cannabis use among adults, but not so far among youth. It has also increased emergency department attendances and hospitalizations for some cannabis‐related harms. The relatively modest effects on cannabis use to date probably reflect restrictions on the number and locations of retail cannabis outlets and the constraints on commercialization under a continued federal prohibition of cannabis. Future evaluations of legalization should monitor: cannabis sales volumes, prices and content of tetrahydrocannabinol; prevalence and frequency of cannabis use among adolescents and adults in household and high school surveys; car crash fatalities and injuries involving drivers who are cannabis‐impaired; emergency department presentations related to cannabis; the demand for treatment of cannabis use disorders; and the prevalence of regular cannabis use among vulnerable young people in mental health services, schools and the criminal justice system. Governments that propose to legalize and regulate cannabis use need to fund research to monitor the impacts of these policy changes on public health, and take advantage of this research to develop ways of regulating can­nabis use that minimize adverse effects on public health.

Recreational cannabis legalization presents an opportunity to reduce the harms of the US medical cannabis industry

“…Hall and Lynskey's masterful essay 1 provides a comprehensive assessment of the public health consequences of recreational cannabis legalization, which wise policy‐makers will consider as they design regulatory systems. We urge US policy‐makers to recognize that recreational cannabis legalization changes the political environment in a way that creates an important public health opportunity: cleaning up the under‐regulated and frequently harmful US medical cannabis industry.…”

Considering the health and social welfare impacts of non‐medical cannabis legalization

“…Hall and Lynskey 1 review the state of knowledge to date regarding cannabis le­galization's impact on public health out­comes. As they correctly observe, the cur­rent (mostly North America‐based) evi­dence base re­garding the impacts of legalization is limit­ed, and mixed, including heterogeneous ef­fects on cannabis use and related harms.…”

Cannabis and public health: a global experiment without control

“…Every few weeks, new findings on the effects of legalizing recreational cannabis use are published. Thus, the review of Hall and Lynskey 1 – or any review for that matter – can only provide a preliminary summary of the collected evidence to date.…”