Stoned drivers: UVIC part of study on marijuana impairment

A University of Victoria researcher is a co-investigator for a study on whether drivers who are high on marijuana cause more crashes than sober drivers.

Scott Macdonald is a scientist at UVic’s Centre for Addictions Research (CARBC) and co-investigator in the Cannabis and Motor Vehicle Crashes: A Multicentre Culpability Study— which is the first of its kind in Canada.

“This is the first study in Canada to compare the active THC levels of those responsible for crashes with those not responsible in non-fatal crashes,” says Macdonald. “A similar study was conducted in Australia for fatally injured drivers and the authors found those with active THC in their blood were significantly more likely to be responsible for their crashes.”

The study is led by Dr. Jeffrey Brubacher, an emergency doctor at Vancouver General Hospital.

Over the next five years, blood samples will be taken from those involved in vehicle accidents where a blood sample is required for treatment. After police reports are analyzed to determine which drivers cause the crash, their identification will be stripped from police records before their blood samples are analyzed for THC—the active ingredient in pot.

This will indicate to researchers whether marijuana use contributed to the accident and may help traffic safety experts develop safer driving policies. According to the Insurance Bureau of British Columbia, impairment is one of the top three contributing factors for fatal car crashes. Each year, on average, 126 people die in motor vehicle crashes involving impaired driving and approximately 32 per cent of motor vehicle fatalities are related to impaired driving.

A recent study on substance use among nighttime drivers in Vancouver, Saanich and Abbotsford found that patterns of drug driving appear to be different from patterns of alcohol and driving. For example, alcohol use among drivers is most common on weekend nights and increases later at night. Drug use is more evenly spread throughout times and days. The study also revealed that 15.5 per cent of drivers tested positive for drugs, alcohol or both; that cannabis and cocaine were the drugs most frequently detected in drivers; and that alcohol use was most common among drivers aged 19 to 24 and 25 to 34 while drug use was more evenly distributed across all age groups.

Last year, CARBC launched a new outreach program aimed at ensuring that youth and young adults understand just how lethal it is to mix drugs. The province-wide project will use a number of different methods, including social media, to educate people between the ages of 16 to 24 who are new drivers.