Prevalence and forms of cannabis use in legal vs. illegal recreational cannabis markets

Samantha Goodman; Elle Wadsworth; Cesar Leos-Toro; David Hammond; International Cannabis Policy Study team

doi:10.1016/j.drugpo.2019.102658

Prevalence and forms of cannabis use in legal vs. illegal recreational cannabis markets

Int J Drug Policy. 2020 Feb:76:102658. doi: 10.1016/j.drugpo.2019.102658. Epub 2020 Jan 9.

Authors

Samantha Goodman¹, Elle Wadsworth², Cesar Leos-Toro³, David Hammond⁴; International Cannabis Policy Study team⁵

Affiliations

¹ School of Public Health and Health Systems, University of Waterloo, Waterloo, ON N2L 3G1, Canada. Electronic address: samantha.goodman@uwaterloo.ca.
² School of Public Health and Health Systems, University of Waterloo, Waterloo, ON N2L 3G1, Canada. Electronic address: ewadsworth@uwaterloo.ca.
³ School of Public Health and Health Systems, University of Waterloo, Waterloo, ON N2L 3G1, Canada. Electronic address: cleostor@uwaterloo.ca.
⁴ School of Public Health and Health Systems, University of Waterloo, Waterloo, ON N2L 3G1, Canada. Electronic address: dhammond@uwaterloo.ca.
⁵ School of Public Health and Health Systems, University of Waterloo, Waterloo, ON N2L 3G1, Canada.

PMID: 31927413
DOI: 10.1016/j.drugpo.2019.102658

Abstract

Background: Recreational or 'non-medical cannabis' has been legalized in several US states, and was legalized federally in Canada in October 2018. There is little comparative data on product use across jurisdictions, particularly with respect to the types of cannabis products used, which differentially impact health.

Methods: Data are from Wave 1 of the International Cannabis Policy Study, collected from Aug 27-Oct 7, 2018. Respondents (n = 27,024) aged 16-65 completed an online survey measuring patterns of cannabis use, quantities and routes of administration. Respondents were recruited from Canada (n = 9976) and US states that had (n = 7362) and had not (n = 9686) legalized non-medical cannabis ('legal' and 'illegal' states, respectively).

Results: Prevalence of at least daily, weekly, and monthly cannabis use were significantly higher in US 'legal' states (11.3%, 18.2%, 25.0%, respectively) than US 'illegal' states (7.4%, 11.6%, 16.8%, respectively; p<0.001) and Canada (8.9%, 14.1%, 19.0%, respectively; p ≤ 0.01). Dried herb was the dominant form of cannabis reported by past 12-month users across all jurisdictions (77.7%-80.8%). Although the amount of dried herb used per year did not differ by jurisdiction (range: 210.3-229.4 g), those in US 'legal' states were significantly more likely to use dried herb daily or weekly than were those in 'illegal' states and Canada (p<0.001). Use of cannabis concentrates, vaped oils, edibles, and drinks was more prevalent among US 'legal' states than 'illegal' states and Canada (p ≤ 0.001). Vaping dried herb was more common in both legal and illegal US jurisdictions than in Canada (p<0.05), whereas Canadians were more likely to smoke dried herb with tobacco (p<0.001).

Conclusion: The prevalence of cannabis use-and use of products such as cannabis concentrates, edibles and drinks-was higher in US states that had legalized cannabis. Additional longitudinal research is required to determine whether these differences reflect causal effects of legalization or pre-existing secular trends.

Keywords: Cannabis; Legalization; Marijuana; Prevalence.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Canada / epidemiology
Cannabis*
Hallucinogens*
Humans
Marijuana Smoking* / epidemiology
Medical Marijuana*
Prevalence
United States / epidemiology

Substances

Hallucinogens
Medical Marijuana

Grants and funding

PJT-153342/CIHR/Canada