Secondhand Harms From Cannabis Use: Findings From Washington State, United States

There are few studies on harms attributed to others' cannabis use. We assessed individual- and contextual-level correlates of secondhand harms from cannabis use and considered whether cannabis legalization support, along with cannabis user status, predicted such harms.

Data were from five repeated cross-sectional, state-representative telephone surveys of Washington State residents ages 18 and older, years 2014-2016. For four surveys, outcome variables were past-12-month reports of experiencing any of five harms (family, traffic-related, vandalism, physical, or financial), and in 2016 only, three harm types separately: (a) harassment, (b) safety-related (traffic, vandalism, physical), and (c) family or financial, attributed to another's cannabis use. All models included a three-category typology comprising participants' own cannabis use and whether they supported cannabis use legalization (user supporter, nonuser nonsupporter, nonuser supporter). We estimated logistic regression models for the full sample and by gender, adjusting for individual- and Census tract-level covariates.

Compared with non-cannabis users supporting legalization, nonusers who did not support legalization reported significantly greater odds of perceiving secondhand cannabis harms. Cannabis users supporting legalization did not differ from nonuser supporters. Predictors of reported harms also differed by gender. Whereas current drinkers had lower odds of reporting any harm from others' cannabis use overall, heavy-drinking women but not men reported greater odds of any cannabis secondhand harm.

Augmenting research on individual harms associated with cannabis use by including secondhand impacts such as social and family problems, along with safety risks, provides a more comprehensive picture of the effects of cannabis use.