Study: Cannabis legalization not associated with increases in traffic injuries in Canada

In a new study, UBC Northern Medical Program Professor Dr. Russ Callaghan has found that the 2018 legalization of cannabis in Canada was not associated with increases in traffic injuries.

A new study conducted by a UBC professor found that cannabis legalization in Canada was not associated with increases in traffic injuries.

The study, from UBC Northern Medical Program Professor Dr. Russ Callaghan, looked at traffic-injury presentations to emergency departments in Ontario and Alberta, 2015-2019, finding no significant changes in traffic-injury emergency department pre-and post-legalization. 

These new traffic-safety laws imposed more severe penalties for impaired driving due to cannabis, alcohol, and combined cannabis and alcohol use.

Dr. Russ Callaghan, UBC Northern Medical Program

“Implementation of cannabis legalization has raised a common concern that such legislation might increase traffic-related harms, especially among youth,” says Dr. Callaghan. “Our results, however, show no evidence that legalization was associated with significant changes in emergency department traffic-injury presentations.”

Dr. Callaghan, along with his team, looked at weekly provincial counts of traffic-injury emergency department (ED) presentations of all drivers and youth drivers in Alberta and Ontario. Youth were defined as individuals aged 14-17 years in Alberta and 16-18 in Ontario. These two provinces were chosen because they are the only two Canadian provinces capturing all ED visits occurring in the general population.

The study was published in Drug and Alcohol Dependence, an international peer-reviewed scientific journal. The lead researcher says he was surprised by the findings and speculates that the lack of an increase in driving injury may be due to stricter laws around impaired driving, passed at the same time as Canada’s Cannabis Act that legalized the plant.  

“Our findings are somewhat surprising,” says Dr. Callaghan. “I predicted that legalization would increase cannabis use and cannabis-impaired driving in the population and that this pattern would lead to increases in traffic-injury presentations to emergency departments.

“It is possible that our results may be due to the deterrent effects of stricter federal legislation, such as Bill C-46, coming into force shortly after cannabis legalization. These new traffic-safety laws imposed more severe penalties for impaired driving due to cannabis, alcohol, and combined cannabis and alcohol use.”

The project included researchers from UNBC, the Centre for Addiction and Mental Health (CAMH) in Toronto, the University of Victoria, and Dalhousie University. Callaghan and his team are currently conducting a follow-up study to examine the impacts of cannabis legalization on traffic fatalities in Canada from 2010-2020. The results of this follow-up study should be available in the summer of 2022.

The study was supported in part by a Canadian Institutes of Health Research Catalyst Grant (Cannabis Research in Urgent Priority Areas).


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