A third of drivers – 33 % – who drink alcohol and use marijuana at the same time reported getting behind the wheel two hours or less after consumption, more than the percentage of drivers who only use alcohol. And it’s a serious problem: the combination worsens driving performance more than either substance by itself.
Those are the main findings of a new study from the Insurance Institute for Highway Safety, a nonprofit financed by the insurance industry, released earlier this month.
“Alcohol impairment is associated with almost 30 percent of the fatalities on our roadways, and we have made very little progress to reduce this toll over the past three decades,” David Harkey, president of the Insurance Institute said in a statement. “Now we are adding another impairing substance to the mix.”
For the study, researchers surveyed more than 3,000 adult drivers in Connecticut, Delaware, New York, North Carolina, South Carolina and Virginia about their opinions and behaviors related to alcohol, marijuana and driving.
In the past year, 71% of respondents reported drinking, 24% reported using marijuana, and 11% – about 1 in 10 – reported simultaneous use of both substances. Among the drivers who reported drinking alcohol, 28% percent said they drank two hours or less before driving and among those who reported using marijuana, 41% said they used the drug two hours or less before driving.
According to an earlier Insurance Institute study, patients who were at a hospital emergency room as the result of a motor vehicle crash only showed an increased crash risk associated with marijuana when it was combined with alcohol. In another study, young adults were found to be more likely to drive or take other risks after using both substances than after consuming marijuana alone.
Additional findings from the report:
–alcohol use in the past year was lowest among drivers ages 18-20 and highest among those 30-39, while past-year marijuana use was lowest among drivers 70 and older and highest among drivers ages 21-29;
–self-reports of driving within two hours of using alcohol, marijuana or both followed the same broad pattern;
-men were more likely than women to use either substance before getting behind the wheel;
– about 25% of men reported drinking and driving, compared with 15% of women;
–12 % percent of men reported using marijuana and 5% reported using both marijuana and alcohol before driving, compared with 8% and 3%of women.
“Policymakers, law enforcement, safety professionals and others will need to work together and implement multiple solutions to save the thousands of lives cut short every year by impaired driving in the United States,” Harkey added.