If you’ve ever listened to someone argue against cannabis legalisation, you’ve likely heard that legalising cannabis will make the roads more dangerous. According to a new study from Canadian researchers, however, that simply isn’t true.
The study documented all diagnosable traffic injuries from car accidents in Ontario and Alberta for roughly four years. It was published online in the journal Drug and Alcohol Dependence on August 27th, 2021.
Specifically, the study compares traffic injuries reported in emergency departments before and after cannabis legalisation. Cannabis became legal in Canada on October 17th, 2018, after the ‘Cannabis Act’ was passed.
As part of their analysis, the study took all emergency department records in the two regions from April 1st 2015, to December 31st 2019. They then divided these records into two groups: one for youth drivers (aged 14-17 in Alberta and 16-18 in Ontario) and one for all drivers. Researchers used Seasonal Autoregressive Integrated Moving Average (SARIMA) models to compare the rates of injury to cannabis legalisation.
Here’s what they found.
In Alberta, researchers analysed a total of 52,752 injuries in the ‘all drivers’ group. Across this group, emergency department visits increased by 9.17 after legalisation, though this figure had a P-value of 0.52 and wasn’t statistically significant. The figure for the ‘youth drivers’ visits wasn’t statistically significant either, as it showed that emergency department visits decreased by 0.66. It included 3,265 injuries.
In Ontario, researchers analysed a total of 186,921 injuries in the ‘all drivers’ group. Across this group, emergency department visits increased by 28.93 visits with a non-statistically significant P-value of 0.30. In the ‘youth drivers’ group, emergency department visits increased by only 0.09 with a P-value of 0.98.
As the study’s results show that traffic injuries didn’t increase after legalisation, researchers concluded that there is no association between cannabis legalisation and traffic injuries.
Implementation of the Cannabis Act was not associated with evidence of significant post-legalization changes in traffic-injury ED visits in Ontario or Alberts among all drivers or youth drivers, in particular.
And as the results weren’t statistically significant, any increase in accidents was likely from another factor or just pure chance.
So next time someone tells you cannabis causes car accidents, show them this study.