Toronto, Ontario -- A new study looking into the impact of edible cannabis products on the performance of drivers has found that young adults can experience measurable driving impairment long after ingestion.
The research, conducted by academics at the University of Saskatchewan and released publicly through materials distributed by the Canadian Automobile Association, examined how a single 10-milligram THC edible affected drivers aged 19 to 30 in a high-fidelity driving simulator.
Compared to the control group, participants who ingested the marijuana products showed slower reaction times, poorer lane control and less consistent speed management following consumption, with impairment most evident about 90 minutes later. At that point, four percent of participants reported feeling safe to drive, despite objective indicators showing reduced driving performance.
Unlike smoked or vaped cannabis, edible products are absorbed more slowly, delaying the onset of impairment. Researchers said this timing effect increases the risk that drivers may already be on the road before impairment peaks, making it harder for individuals to accurately judge whether they are fit to drive.
The results are consistent with earlier research examining edible cannabis and driving. A peer-reviewed study published in Traffic Injury Prevention found increased lane weaving and poorer speed control among drivers after consuming THC edibles.
National road-safety data show cannabis use is a recurring factor in serious collisions in Canada. Toxicology testing found that 16.4 percent of drivers killed in motor vehicle crashes between 2000 and 2010 had cannabis in their system, with the rate highest among drivers aged 16 to 24.
Federal modelling studies have estimated that cannabis-related impairment contributes to hundreds of deaths and several thousand injuries each year, depending on assumptions used.
Self-reported behaviour data also point to ongoing risk: roughly 23 percent of cannabis users say they have driven within two hours of consuming cannabis, and about 14 percent report driving within four hours of ingesting cannabis products, including edibles.
Since legalization, police-reported drug-impaired-driving incidents have increased by more than 40 percent, though those figures include multiple substances and researchers caution that isolating cannabis as the sole cause in individual crashes remains difficult.
