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Nicotine Tob Res. 2019 Dec 23. pii: ntz238. doi: 10.1093/ntr/ntz238. [Epub ahead of print]

Co-use and Mixing Tobacco with Cannabis among Ontario Adults.

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Ontario Tobacco Research Unit, Dalla Lana School of Public Health, University of Toronto, Toronto.
Institute for Implementation Science in Population Health, The City University of New York, New York, NY, USA.



The legalization of non-medical cannabis in 2018 may have important implications for tobacco use in Canada. There is a risk of re-normalizing tobacco use with co-use of tobacco and cannabis introducing nontobacco users to tobacco. Co-use is the use of both substances by the same individual at the same time or on different occasions, as well as mixed together. This study assessed the prevalence of co-use and mixing of tobacco and cannabis among Ontario adults and the characteristics of the users.


Data from the 1996 to 2017 cycles of the Centre for Addiction and Mental Health Monitor (n=4,481) were used to examine trends in prevalence and the proportion of Ontario adults co-using and mixing tobacco and cannabis. Logistic regression was used to study associations between user characteristics and co-use and mixing.


Co-use of cigarettes and cannabis among cannabis users declined from 59.8% in 1996 to 41.7% in 2017. Past-year e-cigarette use was the only predictor of co-use. From 2015 to 2017, 31.1% (95% CI 27.0, 35.9) of Ontario adults who used cannabis reported mixing it with tobacco in the past year. Being white, past-year e-cigarette use, having moderate or high nicotine dependence, and having moderate or high risk for cannabis problems were significant predictors of mixing among cannabis users.


Given the well-established negative health effects associated with tobacco use, alongside a growing evidence base for negative health effects of cannabis smoking, co-use and mixing could pose a considerable public health concern in the context of legalization.


Cannabis; Cigarettes; Co-use; Marijuana; Mixing; Mulling; Smoking; Spliffs; Tobacco


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