A team of researchers from Canadian universities and hospitals conducted this new study to discover whether driving under the influence of cannabis is as dangerous as driving drunk. Researchers conducted this observational study by collecting data on drivers who were admitted to hospitals after being injured in traffic accidents between 2018 and 2021. Out of this group, the study authors singled out nearly 7,000 drivers who were tested for drugs after their accidents.
More than 70% of these injured drivers were completely sober at the time of their accident. Less than 300 drivers, 3.5% of the total, were found to have THC levels of 5ng/mL or more, which is Canada’s legal limit for stoned driving. In contrast, more than three times as many drivers (12.6%) were over the country's legal legal blood alcohol content (BAC) limit of 0.08%. Drivers with high blood alcohol levels were more likely to be seriously injured in these accidents than sober or stoned drivers.
The study also reports that drunk drivers were more likely to get into accidents at nights or on the weekends, while stoned drivers were more likely to be involved in daytime or weekday collisions. People between the ages of 35 and 65 had higher odds of being over the legal THC limit, while rural drivers and men aged 19 to 44 years old were more likely to be over the legal BAC limit.
These findings led researchers to conclude that “alcohol remains a greater threat to road safety” than cannabis, according to NORML.
The researchers do note that the inaccuracies of current cannabis testing methods confound their findings to some degree, though. THC can remain in the body for weeks or even months after use, so standard blood and urine tests cannot accurately identify whether or not a driver is actually stoned when the test is administered. So, some of the injured drivers who tested positive for THC could have been completely sober at the time of the accident.
Another study has confirmed that drivers who smoked weed 24 hours before a driving test drove as safely as sober people, even though their THC blood levels were over Canada's legal limit. Driving immediately after smoking weed is still dangerous, though. Numerous studies have found that stoned drivers have slower reaction times and can struggle to stay in their lanes, compared to sober drivers. Researchers have found that regular stoners are actually better drivers than occasional stoners, though.
But although driving while stoned is risky, driving under the influence of alcohol or other drugs is far more dangerous. Several recent studies report that stoned drivers are only slightly more likely to be involved in traffic accidents, while others have found no link between THC intoxication and accidents at all. Driving under the influence of alcohol, benzodiazepines, or opioids, can greatly increase the risk of accidents and fatalities, though.
Other research studies have pointed out that access to legal weed can also reduce the risk of car accidents as well. Auto insurance reports have found that rates of drunk driving are declining in states where medical marijuana is legal. And in US states that have legalized adult-use cannabis, people are actually less likely to drive while stoned, not more.