After Oregon legalized recreational marijuana in 2015, counties with the highest density of both marijuana and alcohol retail outlets saw a significant increase in adolescent co-use of alcohol and marijuana.
Cannabis policy makers, local zoning boards, adolescent prevention specialists
Co-use increase was significant only in highest outlet density counties
What the researchers found
Post-legalization, there was a significant increase in past-30-day alcohol and marijuana co-use in 2016 in counties with the highest retail outlet density. The relationship between outlet density and co-use was mediated by adolescent beliefs about availability, parent approval, and risk. There were also post-RML increases in perceived risk and perceived parent approval of use.
Why it matters
Understanding how retail density affects adolescent substance use patterns can inform zoning and licensing decisions. The finding that beliefs mediate the outlet density-use relationship suggests both environmental and educational interventions are needed.
The numbers in context
71,870 11th graders; 36 Oregon counties; 2010-2018 data; significant co-use increase in 2016 in highest-density counties; beliefs about availability, parent approval, and risk mediated the outlet density-co-use relationship
How the study worked
Multi-level logistic regression of biennial data from the Oregon Student Wellness Survey, 2010-2018, covering 71,870 11th graders across 36 counties. Examined associations between recreational marijuana legalization, county-level outlet density, and adolescent co-use and beliefs.
What this study cannot tell us
Observational ecological design cannot establish individual-level causation. Biennial survey data may miss short-term fluctuations. Oregon may not represent other states. Outlet density is an imperfect proxy for actual accessibility to minors.
How to read the evidence
Large representative sample with multi-level design and multiple survey waves, though ecological design limits individual-level inference.
When this study was published
Published in 2021 using 2010-2018 survey data.
The bigger picture
This suggests that cannabis legalization effects on adolescents are not uniform across regions but depend on local retail environments. Communities can potentially mitigate adolescent use impacts through outlet density regulations.
Questions still open
- Is there an outlet density threshold below which adolescent co-use is not affected? Do delivery services and online sales undermine the protective effect of outlet density limits?
Common questions
Did legalization increase teen marijuana use everywhere?
How did beliefs play a role?
Read the original research
Retail Availability of Recreational Marijuana and Alcohol in Oregon Counties and Co-Use of Alcohol and Marijuana and Related Beliefs among Adolescents.
Substance use & misuse, 56(3), 345-352
Citation
García-Ramírez, Grisel; Paschall, Mallie J; Grube, Joel W. (2021). Retail Availability of Recreational Marijuana and Alcohol in Oregon Counties and Co-Use of Alcohol and Marijuana and Related Beliefs among Adolescents.. Substance use & misuse, 56(3), 345-352. https://doi.org/10.1080/10826084.2020.1858104