A national survey conducted by researchers at Washington State University found more than 52 percent of marijuana users think it's safe to drive high.
The survey was conducted in collaboration with researchers at the University of California and the Bastyr University Research Institute between November 2013 and December 2014 and reached nearly 2,000 participants in 50 states.
Carrie Cuttler, assistant professor with WSU's department of psychology, said the work found the public more or less split on the issue.
"With legalization, people seemed to be quite concerned that people are going to be driving high and that's going to pose a major public safety risk," Cuttler said. "We just wanted to get a better sense of just how many people think that it is actually safe and how many people actually engaged in the practice."
Cuttler said a similar proportion of respondents, about 52.4 percent, admitted to driving within an hour of consuming marijuana, but only about 4 percent reported experiencing any kind of traffic accident while driving high. She said while marijuana may not impair users on the same level as alcohol, high driving still about doubles the risk a motorist will get into an accident. Cuttler said drunk drivers are about eight times more likely to get into an accident than if they were sober and those who text while driving are about 25 times more likely to get into an accident.
Driving is already a dangerous activity without throwing drugs into the mix, Cuttler said. Ideally, she said, drivers are not only sober but free of distraction and focused on the road. Marijuana consumption may not be equivalent to a blood alcohol level beyond .08, but that doesn't make it "safer."
"There is a significant increase in risk - it's not a huge increase, but there is still a significant increase," Cuttler said. "You're just adding to the risk unnecessarily."
Cuttler said there are no known reliable indicators of acute marijuana intoxication - making it difficult to measure the degree of impairment at traffic stops. Currently, police can test a drivers' blood for THC metabolites associated with imbibing cannabis but frequent users could carry those in their blood stream for up to a month since their last puff. Also, level of impairment isn't necessarily tied to quantity consumed. She pointed out more regular users may experience less of an intoxicating effect than those who are new to the drug.
Cuttler's research identified a number of interesting correlations, including that older people with less education who use more cannabis tend to be more comfortable with high driving. Inversely, younger people with a comparable level of consumption who are well-educated are also fairly likely to drive within an hour of consuming marijuana.
Cuttler's findings suggest states that legalize recreational marijuana consumption actually trend downward in terms of respondents who admit to driving high.
"Since legalization, the prediction would be that people are thinking that cannabis is less risky, people might think that it's more safe to drive, people might actually be driving high more," Cuttler said. "We found the opposite, we found decreases - we found that fewer people said it's safe to drive high and fewer people reported driving high since legalization."
Scott Jackson can be reached at (208) 883-4636, or by email to firstname.lastname@example.org.