Car crashes and deaths are on the rise in U.S. states that have legalized recreational marijuana, a new study finds.
"Marijuana, like alcohol and just about every other drug, changes how you feel and how you behave. That's the purpose of a drug. And that changes how you drive. We all need to realize that driving after using marijuana is a bad idea," said lead researcher Charles Farmer, vice president for research and statistical services at the Insurance Institute for Highway Safety.
His team found that after marijuana legalization, the rate of car crashes with injuries increased by nearly 6%, while fatal crashes rose by 4%. No increase in these crashes was seen in states that hadn't legalized marijuana, the researchers noted.
These results are consistent with prior studies, Farmer said. "It's becoming more and more clear that the legalization of marijuana doesn't come without cost. But marijuana legalization is still a novelty, and there's hope that these early trends can be turned around," he added.
Farmer thinks there are ways to help prevent the consequences of driving high. "Maybe, with the right education and enforcement strategies, states that are either considering or in the process of legalization can avoid the increase in crashes," he said.
For the study, Farmer and his colleagues looked at five states that legalized recreational marijuana for people 21and older (Colorado, Washington, Oregon, California and Nevada) and compared them with states that did not legalize pot (Arizona, Idaho, Montana, New Mexico, Utah and Wyoming).
They found that after legalization, but before retail pot sales started, the rate of car crashes with injuries jumped nearly 7%. After sales began, the crash rate dipped slightly (less than 1%), but the rate of fatal crashes shot up about 2% before and after retail sales began.
Often, drivers under the influence of marijuana drive slowly, the researchers noted. They may not be able to avoid a crash, but their lower speed may make the collision less deadly, Farmer noted.
In previous studies, Farmer's team found that marijuana use affects reaction time, road tracking, lane keeping and attention, all of which can make a crash more likely.
Farmer doesn't believe marijuana legalization is the only cause of rising collision rates, and the study can't prove a direct cause-and-effect relationship. And unlike alcohol testing, there are no objective measures of impairment linked to marijuana, so it's not possible to accurately account for the role marijuana plays in car crashes, he said.
The changes in crash rates varied by state: Colorado had the biggest jump (18%) and California the smallest (6%) after both legalization and the start of retail sales. Nevada's rate fell (7%). For fatal crashes, increases occurred in Colorado (1%) and Oregon (4%), while declines were found in Washington (2%), California (8%) and Nevada (10%).
Alex Otte, national president of MADD (Mothers Against Drunk Driving), said, "We know that driving impaired by any drug, alcohol, marijuana or otherwise, is 100% preventable. It's not an accident. It's not a mistake. It's a choice."
What's needed is to change the culture so people understand that it's not safe to drive after using pot, she said.
"We hear all the time in pop culture things like, 'Maybe I'm a better driver when I'm high'," Otte said. "I think people just aren't aware, as much as they are with alcohol, that there is such a risk associated with driving under the influence of marijuana or other drugs, and I think a lot of it comes down to awareness."
In the future, Otte hopes there will be ways to quantify pot's effects on driving, like there are for alcohol.
"We know that roadside tests and things like that to help an officer determine if that person is safe to drive are so important and so needed," she said.
Impairment by any drug is a threat to you and everyone else on the road, Otte said. "Even one person injured or killed is one too many," she said. "I want people to know that this is a choice and they have the option to make the right choice and not to drive when high."
The report was published July 19 in the Journal of Studies on Alcohol and Drugs.