Living Near a Cannabis Store Linked to 12% More Cannabis ER Visits
In a rigorous natural experiment studying 6 million Ontarians, neighborhoods within 1km of a cannabis store saw a 12% relative increase in cannabis-related ER visits compared to neighborhoods without nearby stores.
Quick Facts
What This Study Found
Neighborhoods exposed to cannabis stores (within 1000m) had a monthly increase of 1.30 cannabis-attributable ED visits per 100,000 persons (95% CI: 0.51-2.09, p<.001) compared to matched unexposed neighborhoods. This represented a 12% relative increase (CI: 6%-19%) in monthly visit rates. Cannabis ED visits were already increasing before stores opened, but store proximity accelerated the trend.
Key Numbers
6.14 million people. 10,574 neighborhoods. 2017-2022 study period. +1.30 ED visits/100,000/month in exposed neighborhoods (p<.001). 12% relative increase (95% CI: 6%-19%). Exposure defined as store within 1000m.
How They Did This
Population-based natural experiment in Ontario, Canada (2017-2022). 10,574 neighborhoods containing 6.14 million persons aged 15-105. Tracked all cannabis store openings. Compared cannabis-attributable ED visit rates in newly exposed neighborhoods (store within 1km) vs. matched unexposed neighborhoods using difference-in-differences design.
Why This Research Matters
This is among the strongest evidence that cannabis retail density directly affects health harms. It suggests policymakers can reduce cannabis-related ER visits by limiting store density or prohibiting stores in certain areas — a practical, implementable public health tool.
The Bigger Picture
Just as limiting alcohol outlet density reduces alcohol-related harms, this study shows the same principle applies to cannabis. Countries pursuing legalization can use store density limits as a public health lever — more stores means more harms, controllably.
What This Study Doesn't Tell Us
Observational natural experiment — unmeasured confounding between exposed and unexposed neighborhoods possible. Cannabis ED visits were already trending up. Cannot determine individual-level store use. Ontario-specific regulatory context.
Questions This Raises
- ?What is the optimal distance/density limit for cannabis stores?
- ?Would online-only sales avoid the proximity effect?
- ?Do store-level regulations (hours, advertising) matter as much as location?
Trust & Context
- Key Stat:
- Evidence Grade:
- Large population-based natural experiment with difference-in-differences design — among the strongest quasi-experimental evidence possible.
- Study Age:
- Published in 2026 in Annals of Internal Medicine, examining Ontario's 2018-2022 cannabis retail rollout.
- Original Title:
- Effect of Nonmedical Cannabis Legalization and Exposure to Retail Stores on Cannabis Harms : A Quasi-experimental Study.
- Published In:
- Annals of internal medicine, 179(1), 12-22 (2026)
- Authors:
- Friesen, Erik Loewen, Pugliese, Michael(13), MacDonald-Spracklin, Rachael(5), Manuel, Doug, Wilson, Kumanan, Hobin, Erin, Pinto, Andrew D, Myran, Daniel T
- Database ID:
- RTHC-08266
Evidence Hierarchy
Frequently Asked Questions
Does having a cannabis store nearby increase health harms?
This study of 6 million people found neighborhoods within 1km of a cannabis store had 12% more cannabis-related ER visits than matched neighborhoods without stores. The finding suggests store proximity increases access and associated harms.
Can regulating store locations reduce cannabis harms?
This evidence suggests yes. Limiting store density, prohibiting stores in certain areas, or capping the total number of stores could offer measurable public health benefits — similar to how alcohol outlet regulations reduce alcohol-related harms.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-08266APA
Friesen, Erik Loewen; Pugliese, Michael; MacDonald-Spracklin, Rachael; Manuel, Doug; Wilson, Kumanan; Hobin, Erin; Pinto, Andrew D; Myran, Daniel T. (2026). Effect of Nonmedical Cannabis Legalization and Exposure to Retail Stores on Cannabis Harms : A Quasi-experimental Study.. Annals of internal medicine, 179(1), 12-22. https://doi.org/10.7326/ANNALS-25-01960
MLA
Friesen, Erik Loewen, et al. "Effect of Nonmedical Cannabis Legalization and Exposure to Retail Stores on Cannabis Harms : A Quasi-experimental Study.." Annals of internal medicine, 2026. https://doi.org/10.7326/ANNALS-25-01960
RethinkTHC
RethinkTHC Research Database. "Effect of Nonmedical Cannabis Legalization and Exposure to R..." RTHC-08266. Retrieved from https://rethinkthc.com/research/friesen-2026-effect-of-nonmedical-cannabis
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.