Tatiana Ogourtsova, Ph.D., a postdoctoral fellow who works at the University of British Columbiaâ€™s Faculty of Medicine, Paediatrics, also says the relationship between medical marijuana use and driving was complicated.Â
Ogourtsova co-authored a study published in October that found marijuana causes an increased risk of crashes among young drivers, even five hours after they use marijuana. But, she says, â€śWe need to be very careful on how we extrapolate this to other populations, including medicinal users,â€ť who might have higher tolerance to other products.
Ogourtsovaâ€™s team had recreational marijuana users test aÂ driving simulator, after smoking a typical dose of marijuana. Asked how confident they were in driving, nearly 80 percent reported they didnâ€™t feel safe, Ogourtsova says.
â€śThey had this actually adequate self-awareness of their abilities following their use of cannabis,â€ť she says. Complex driving tasks became far more difficult after smoking marijuana, she adds.
â€śThe road is always unexpected, anything can happen on the road, drivers need a very quick and accurate response in order to maneuver safely.â€ť
Research into driving while impaired is complicated byÂ the variables associated with THC (tetrahydrocannabinol), the psychoactive component of cannabis.
â€śWeâ€™ve had a lot of change in the marijuana thatâ€™s available to people today,â€ť says Bonar, the University of Michigan researcher, as today’s products often have much higher amounts of THC, making them more potent.Â The current market offers consumers several ways to use marijuana, for one thing, and those devices affect people differently.
And that market is growing rapidly: Federal law still prohibits the possession, use, or sale of recreational and medical marijuana, but now 10 states and Washington, D.C., allow recreational use, while another 23 allow medical marijuana. Canada legalized recreational marijuana in 2018, only the second country in the world to do so.Â
How law enforcement determines whether a driver is impaired by marijuana also remains a complicated and unresolved issue.Â