Washington state officials are concerned about an uptick last year in fatal crashes in which drivers tested positive for active THC, the psychotropic in marijuana.
The numbers appear to show not just that more people may be using marijuana, but that an increasing number are doing so right before they drive, said Dick Doane, a research investigator with the Washington Traffic Safety Commission.
“What this indicates to us is that people are engaging in a risky practice of smoking marijuana right before they get into their cars,” Doane said. “And for too many, that has resulted in tragic costs.”
In 2012, Washington voters approved Initiative 502 to legalize recreational marijuana use for those 21 and over.
According to data the traffic safety commission released Wednesday, 89 drivers involved in last year’s 429 fatal crashes tested positive for some form of marijuana use.
Of those drivers, 85 percent tested positive for active THC, and not just the residual form of the drug that can remain in a person’s system for days or weeks.
That’s up from 2013, when roughly two-thirds of the 60 marijuana-positive drivers involved in fatal crashes tested positive for active THC.
It’s also a big increase from 2010, officials said, when fewer than half of 81 pot-positive drivers involved in fatality accidents had the active form of the drug in their systems.
The data released Wednesday are the result of the commission reviewing fatal crashes of the past few years to distinguish what type of THC was present in drivers’ blood, spokeswoman Shelly Baldwin said.
Baldwin called the increased presence of active THC as a factor in fatal crashes “concerning.”
“It really has us worried that people really aren’t getting the message that it’s not safe — that it’s really not a good idea to use marijuana or any other drug and drive,” Baldwin said.
Two metastudies the commission frequently cites found that driving with any amount of active THC in one’s system roughly doubles the risk of getting into a traffic accident.
Yet pot use doesn’t appear to affect drivers nearly as much as alcohol.
The commission estimates that someone driving with a blood-alcohol content of 0.15 — almost double the legal limit of 0.08 — or higher is about 25 times more likely to get into a fatal crash than someone who drives sober.
Another study this year by the National Highway Traffic Safety Administration found that, after adjusting for age, gender, race and alcohol use, drivers who tested positive for marijuana weren’t more likely to crash than sober drivers.
Doane said more research still needs to be done on how THC affects driving, as well as how legalization of marijuana might relate to trends in traffic accidents.
“There’s just a lot we don’t know yet,” Doane said of Washington’s 2014 crash data. “Is this directly the result of the legalization of marijuana sales? That seems like a reach at this point.”