September 7, 2023 – Canada's legalization of recreational marijuana in 2018 is linked to a dramatic increase in marijuana-related traffic accidents requiring emergency room treatment, a brand new study shows.
The researchers found that the most important increases occurred when more varieties of marijuana products became available and were offered by more firms. For comparison, researchers examined alcohol-related traffic accidents and located that there was no corresponding increase in emergency room visits over the identical period.
The findings, published Wednesday in JAMA network opened, suggest “that cannabis legalization has played an important role in the increasing rates,” said lead creator Daniel Myran, MD, MPH, in a Press release. Myran is a family physician and fellow of the Canadian Institutes for Health Research.
For the study, researchers analyzed data on traffic-related injuries treated in emergency departments within the Canadian province of Ontario, the country's most populous province with greater than 14 million residents. The investigation period prolonged from January 2010 to December 2021. The traffic accidents also included those involving motorized vehicles or pedestrians and cyclists. Marijuana was considered a contributing factor if a medical code for marijuana use was listed within the patient's visit record.
During the 12-year study period, 426 marijuana-related traffic accidents were treated in emergency rooms. The rate of marijuana-related injuries increased from 0.18 emergency visits per 1,000 automotive accidents in 2010 to 1.01 visits per 1,000 accidents in 2021. That represents a 475% increase over all the study period.
Because the legalization of recreational marijuana in Canada led to a gradual increase in access to the drug, researchers also compared three time periods to see whether different levels of access affected the frequency of traffic-related emergency room visits related to marijuana use. The periods compared were the nearly eight-year pre-legalization period, the early legalization period from October 2018 to March 2020, and the broad commercialization period of legalization, which ranged from April 2020 to December 2021. They found that:
- Comparing the pre-legalization period to the pre-legalization period, incidents increased by 94%.
- The variety of incidents increased by 223% when comparing the early legalization phase with the widespread commercialization phase.
The researchers found that the broad commercialization period overlapped with the beginning of the pandemic, leading to dramatically different driving patterns.
Men, people ages 19 to 21, and other people living in lower-income neighborhoods were the most probably to go to the emergency room for marijuana-related traffic accidents.
There are laws in Canada that limit the quantity of the drug in an individual's blood while driving. The study's authors concluded that more education about marijuana-impaired driving and stronger enforcement are needed within the country.