A population-based natural experiment investigated how living near cannabis retail stores relates to cannabis-related harms. The researchers found a connection between store exposure and higher rates of harm, with the largest increases appearing in neighborhoods that had many stores located close together. These results indicate that limiting the number of cannabis retailers, reducing concentrated clusters of stores, or restricting store placement in certain areas could support public health goals. The study appears in Annals of Internal Medicine.
A research team from North York General Hospital and partner institutions analyzed data from 6,140,595 people living in Ontario, Canada. Participants were between 15 and 105 years old and lived in 10,574 neighborhoods from April 2017 through December 2022. The team examined whether living near a cannabis retail store after legalization in October 2018 influenced neighborhood-level rates of cannabis-related emergency department (ED) visits.
To define exposure, the researchers used provincial records on cannabis store locations. Neighborhoods were considered exposed if they were located within 1000m of a cannabis retail store and unexposed if they were situated more than 1000m away. The main measure of health impact was the rate of cannabis-attributable ED visits per 100,000 people aged 15 years or older.
The analysis showed that exposed neighborhoods were more commonly located in major urban centers and were disproportionately represented in the lowest income quintile compared to unexposed neighborhoods. After a cannabis store opened nearby, exposed neighborhoods did not show a rise in monthly cannabis-attributable ED visits. By contrast, unexposed neighborhoods experienced a decline in monthly ED visits over the same period.
When the two groups were compared directly, exposed neighborhoods had a 12% increase (CI, 6% to 19%) in the absolute rate of cannabis-attributable ED visits relative to unexposed areas. The researchers also observed that neighborhoods with several cannabis stores located within 1000m experienced greater increases in ED visits than areas with fewer stores. According to the authors, these findings suggest that the combination of legalization and retail expansion may introduce public health risks that differ from legalization on its own.