Crashes caused by drunk drivers are well documented, but the record is much hazier when it comes to tracking collisions caused when the person behind the wheel is stoned on marijuana.
The Centre for Addictions Research B.C. (CARBC) is launching Canada’s first study to determine the actual risk of smoking cannabis prior to driving a motor vehicle.
The million-dollar study, co-investigated by the University of Victoria’s CARBC researcher Scott Macdonald, is based on blood samples of 3,000 drivers who expected to be hospitalized for injuries at five trauma units across the province.
“We don’t know the actual risk involved at various levels of smoking pot,” Macdonald said. “If you smoke two joints, what is the actual rick of being in a crash and how much higher is it than if you’re sober?”
For the next five years, blood samples will be taken from anyone in a vehicle accident, so long as a blood sample is required for treatment.
After police have determined who is at fault in each crash, the driver’s identification will be wiped from the record before the blood samples are tested for THC — the active ingredient in cannabis.
“It is a very big undertaking,” Macdonald said.
What sets this study apart from others in the past is the research of the study as well as the quality of data collected.
Other studies have used less-valid means of measuring the THC level in the body, including saliva and urine tests which do not measure active THC.
CARBC’s Cannabis and Motor Vehicle Crashes: A Multicentre Culpability Study could have the same consequences for marijuana and driving that previous studies of alcohol’s role in vehicle crashes had on impaired driving laws, Macdonald said.