Canadian drug-impaired driving laws penalize drivers found to have blood THC levels of between two to five nanograms per millilitre. However, new research led by the University of British Columbia suggests that THC levels less than five nanograms/ml of blood do not lead to an increased risk of causing car crashes in most drivers.
The findings, published in the journal Addiction, adds to a growing body of research into the road safety impacts of not only THC, but a variety of legal and illegal substances, suggesting more research is needed to inform drug-impaired driving laws.
“At blood levels of less than five nanograms/ml, THC does not appear to be associated with an increased risk of crashing,” said Dr. Jeffrey Brubacher, associate professor in the department of emergency medicine at UBC and principal investigator on a five-year study investigating the role of cannabis in causing motor vehicle crashes. Read more from UBC News