Canadian study links cannabis legalization to increase in car accidents

The results of a recent study published in JAMA Network Open claim to have found a link between cannabis legalization and an increase in traffic accidents.

The study was conducted by researchers at the University of Ottawa and examined emergency rooms in Ontario, Canada over a period of 13 years (January 2010 to December 2021, which is actually 12 years, but the study says 13, so what do I know? ). ), in the end, they found a 475.3% increase in traffic accidents that resulted in an emergency room visit where the driver had cannabis in his system at the time of the accident.

“This cross-sectional study found a large increase in cannabis involvement in emergency room visits for traffic accidents over time, which may have accelerated following the commercialization of non-medical cannabis,” the study concluded. “Although the frequency of visits was rare, they may reflect broader changes in driving under the influence of cannabis. Greater prevention efforts, including targeted education and policy interventions, in regions with legal cannabis are warranted.”

At first glance, 475.3% sounds like a big number, and suffice to say, many of the anti-cannabis media outlets that have repackaged that number into a scary-sounding headline are counting on their readers to look no further rely on their word Cannabis legalization and car accidents must be linked. I’m a journalist, not a scientist, but I can share a few facts about the study that might make this large number seem a little less scary.

First, the study was only conducted in Ontario, Canada. In terms of sample size, this is a city in a country with very specific cannabis laws. Therefore, it is not entirely correct to apply the blanket term “legalization” to a very specific set of laws. The study even states in the introduction:

“Another study also found no increase in the total number of hospitalizations for traffic accidents in Canada over a 2.5-year period following legalization. “Crucially, the slow development of the cannabis retail market in Canada and the overlap of the legalization period with the COVID-19 pandemic significantly limit the ability of these studies to assess the impact of legalization,” the study states.

It is also important to understand that the total number of traffic accidents involving cannabis-related injuries over the 13-year period totaled 426 out of 947,604. This percentage figure is 0.04%, which is even lower when compared to the total number of traffic accidents without taking emergency rooms into account. That’s by no means insignificant, but at first glance it’s probably a much less daunting number than 475.3%.

A key piece of data highlighted in the study was that men appeared to be at greater risk than women of being involved in such accidents in which cannabis intoxication was considered a factor. This stands to reason, as a 2016 National Institute of Health study found that men use cannabis far more frequently than women and in greater quantities per consumption.

“Of the 418 people with documented cannabis involvement, 330 (78.9%) were male, 109 (25.6%) were 16 to 21 years old (mean). [SD] Age at visit: 30.6 [12.0] years) and 113 (27.0%) had an emergency department visit or hospitalization for substance use in the two years prior to their emergency room visit for traffic accidents,” the study said.

The final and arguably most important question to ask when analyzing the results of a study is: “Who paid for it?” Studies cost money, and it goes without saying that people who have money often try to to use this money to influence the results of otherwise scientifically based observation methods. This is America (or Canada in this case), after all. However, this study was fully funded by grants from the Canadian Institute of Health and the University of Ottawa, meaning there appears to be no private money attempting to influence these results.

Regardless of my quibbles, this study showed something important: there is a small but statistically significant chance that there is a link between cannabis legalization and serious traffic accidents, but more context and studies are needed to be sure.

“The results of this repeated cross-sectional study suggest that serious cannabis-related traffic injuries have increased over time. Legalization of non-medical cannabis with widespread retail access and a greater variety of cannabis products may have further increased these visits despite laws specifically aimed at deterring cannabis-impaired driving,” the study says. “Younger adults and men appear to be at particularly increased risk of cannabis-related traffic accidents. There is a potential need for greater interventions, including cannabis driving education, enforcement measures, and policies to regulate access to commercial retail markets.”