Retail Availability of Recreational Marijuana in Oregon Counties and Marijuana Use and Related Beliefs Among Adolescents

Introduction: Many states that have legalized recreational marijuana allow localities to place restrictions on sales or use that are more stringent than those enacted at the state level. In Oregon, for example, cities or counties may restrict or prohibit the operation of recreational marijuana producers, processors, wholesalers and retailers. Local policies may be particularly important because they shape the environments in which people live and interact on a daily basis. This study investigated whether legalization of recreational marijuana sales in Oregon counties and retail availability of marijuana (outlet density) were associated with increases in marijuana use and beliefs supportive of marijuana use among adolescents.

Methods: Biannual data for 6^th, 8^th and 11^th graders from the Student Wellness Survey (SWS) in 36 Oregon counties from 2010 to 2016 (N=191,543) were analyzed to assess relative changes in past-30-day marijuana use and marijuana-related beliefs (perceived availability of marijuana, perceived risk of marijuana use, perceived parent approval of marijuana use) in counties that allowed recreational marijuana sales in 2015 compared to counties that did not. Analyses were also conducted with the 2016 SWS data (n=50,791) determine whether county-level associations between allowing recreational marijuana sales and outlet densities with marijuana use could be accounted for by perceived availability, risk of harm, and parents’ approval of marijuana use.

Results: Higher rates of past-30-day marijuana use and more favorable beliefs about marijuana use were observed in counties that allow recreational marijuana sales. The prevalence of past-30-day marijuana use declined from 2010 to 2014, but increased from 2014 to 2016 in both counties that did and did not allow recreational marijuana sales. There were parallel increases in perceived availability of marijuana and perceived parent approval of marijuana use from 2014 to 2016 and a steady decline in perceived risk of marijuana use from 2010 to 2016. Analyses of the 2016 SWS data suggested that the associations between allowing recreational marijuana sales and past-30-day marijuana use could be accounted for by density of licensed marijuana retail outlets and marijuana-related beliefs.

Conclusions: There was a statewide increase in the prevalence of marijuana use and in beliefs favorable to marijuana use after legalization of recreational marijuana sales in 2015. Increasing retail availability of marijuana for recreational use may increase marijuana use among adolescents by increasing beliefs favorable towards marijuana use.