Marijuana Use By Drivers Linked With Increased Risk of Motor Vehicle Crashes

Drivers who test positive for marijuana or who drive within three hours of using marijuana are more than twice as likely to be involved in motor vehicle crashes compared with those who don’t use the drug, according to a new review of studies.

Science Daily reports researchers at Columbia University in New York combined the results of nine studies, and found the greater the amount of marijuana compounds in a person’s urine, the greater the risk of a car crash. The study also found more frequent self-reported marijuana use was associated with a greater risk of a motor vehicle accident.

The study found 28 percent of drivers who died in an accident, and more than 11 percent of drivers in general, tested positive for non-alcohol drugs. Marijuana was the most commonly detected substance.

Eight of the nine studies found drivers who use marijuana are significantly more likely than people who don’t use marijuana to be involved in motor vehicle accidents. The results appear in the journal Epidemiologic Reviews.