Canada: Similar to the findings in the alcohol literature, the upper 10% of cannabis users accounted for approximately two-thirds of all cannabis consumed in the country

Who consumes most of the cannabis in Canada? Profiles of cannabis consumption by quantity. Russell C. Callaghan et al. Drug and Alcohol Dependence, September 25 2019, 107587. https://doi.org/10.1016/j.drugalcdep.2019.107587

Highlights
• Study pooled Waves 1-3 of the 2018 Canadian National Cannabis Survey (n = 18,900).
• Surveys assessed cannabis use by quantity across seven major cannabis-product types.
• A standard joint measure was created, based on physical production equivalencies.
• The upper 10% of Canadian cannabis users accounted for 66% of all cannabis consumed.

Abstract
Aim: To establish whether the population-level pattern of cannabis use by quantity is similar to the distributions previously reported for alcohol, in which a small subset of drinkers accounts for a majority of total population alcohol consumption.

Method: The current study pooled Waves 1-3 of the 2018 National Cannabis Survey (n = 18,900; 2584 past-three-month cannabis users), a set of stratified, population-based surveys designed to assess cannabis consumption and related behaviors in Canada. Each survey systematically measured self-reported cannabis consumption by quantity across seven of the major cannabis-product types. In order to enable the conversion of self-reported consumption of non-flower cannabis products into a standard joint equivalent (SJE: equal to 0.5 g of dried cannabis), we created conversion metrics for physical production equivalencies across cannabis products.

Results: Similar to the findings in the alcohol literature, study results show that cannabis consumption is highly concentrated in a small subset of users: the upper 10% of cannabis users accounted for approximately two-thirds of all cannabis consumed in the country. Males reported consuming more cannabis by volume than females (approximately 60% versus 40%), with young males (15-34 years old) being disproportionately represented in the heaviest-using subgroups.

Conclusions: Most of the cannabis used in Canada is consumed by a relatively small population of very heavy cannabis users. Future research should attempt to identify the characteristics of the heaviest-using groups, as well as how population-level cannabis consumption patterns relate to the calculus of cannabis-related harms in society.

Keywords: CannabisMarijuanaSurveyQuantityStandard Joint