Bayesian spatiotemporal analysis of California ZIP codes found no association between recreational cannabis outlet openings and self-harm, while alcohol outlet density showed a strong link to nonfatal self-harm.
Public health policymakers, legalization researchers, mental health epidemiologists
Zero significant association between cannabis outlet openings and self-harm injuries
What the researchers found
Recreational cannabis outlets were not associated with fatal or nonfatal self-harm injuries; a hypothetical 20% reduction in alcohol outlets was associated with 1.59 fewer nonfatal self-harm injuries per 100,000; no interaction between cannabis and alcohol outlet densities.
Why it matters
Concerns that cannabis legalization might increase self-harm are not supported by this analysis, while alcohol outlet density remains a significant modifiable risk factor.
The numbers in context
If cannabis outlets had never opened: -0.35 per 100,000 nonfatal self-harm (95% CI: -1.25, 0.51); 20% alcohol outlet reduction: -1.59 per 100,000 nonfatal (95% CI: -2.60, -0.59); strongest effects in ages 15-34.
How the study worked
Bayesian spatiotemporal analysis of quarterly ZIP code-level data from California (2017-2019) using statewide data on recreational cannabis outlets, alcohol outlets, and hospital discharges/deaths from self-harm; adjusted for confounders and spatial autocorrelation.
What this study cannot tell us
Three-year window may miss longer-term effects; ecological study cannot capture individual-level use patterns; California-specific results may not generalize; could not account for illicit market dynamics.
How to read the evidence
Rigorous Bayesian spatiotemporal methodology with statewide data, though ecological design and short timeframe are limitations.
When this study was published
Published 2025, data from 2017-2019
The bigger picture
This adds to growing evidence that cannabis retail access does not worsen population-level mental health outcomes, in contrast to alcohol availability.
Questions still open
- Would longer follow-up reveal delayed effects of cannabis outlet openings? Do other states show similar null findings for cannabis outlets? Could cannabis outlet access reduce self-harm by displacing alcohol use?
Common questions
Did cannabis stores opening lead to more self-harm?
What about alcohol outlets?
Read the original research
Examining the Interactive Associations of Cannabis and Alcohol Outlets With Self-harm Injuries in California: A Spatiotemporal Analysis.
Epidemiology (Cambridge, Mass.), 36(2), 196-206
Citation
Charris, Rafael; Ahern, Jennifer; Apollonio, Dorie E; Jent, Victoria; Jacobs, Laurie M; Jung, Shelley; Schmidt, Laura A; Gruenewald, Paul; Matthay, Ellicott C. (2025). Examining the Interactive Associations of Cannabis and Alcohol Outlets With Self-harm Injuries in California: A Spatiotemporal Analysis.. Epidemiology (Cambridge, Mass.), 36(2), 196-206. https://doi.org/10.1097/EDE.0000000000001822