Cannabis Increases Fatal Crash Risk

Drivers who tested positive for cannabis over a 10-year period were 29 percent more likely to cause a fatal crash than drivers who didn't use the drug, says a study in the current issue of the Canadian Journal of Public Health.Researchers analyzed test results from 32,543 U.S. motorists. Between 1993 and 2003, 1,567 of those drivers tested positive for cannabis, but not for alcohol.

"Those who tested positive for cannabis had 29 percent more risk of having committed a driving action that led to the crash than those who did not," study leader Michel Bedard, director of public health at Lakehead University in Thunder Bay, Ontario, told CBC News.

The increased risk linked to cannabis persisted even after the researchers factored in age, sex and previous driving record."It tells us that cannabis is not a safe substitute for alcohol, and I especially mean that for young people," Bedard told CBC News.

The study authors said more research is needed in order to determine at what dose cannabis starts to impair driving ability.