On the high road: driving under the influence of cannabis in Ontario.

While cannabis is the most frequently found illegal drug in drivers killed or injured in motor vehicle collisions, little is know about driving under the influence of cannabis (DUIC) in the general population. We report information on the incidence of DUIC in a representative sample of the Ontario adult population. Among all drivers, 1.9% reported DUIC in the previous 12 months. Several factors influenced the likelihood of reported DUIC, including gender, age, marital status and education level. Among cannabis users, DUIC appeared to be a relatively common behaviour; 22.8% reported DUIC, and the probability of the behaviour was significantly influenced by gender and education level. As well, DUIC and drinking-driving were strongly related in this sample. These data underscore the need to obtain more information on this behaviour, including a more complete understanding of any risks involved.