Crash rates spiked with the legalization of recreational marijuana use and retail sales in California, Colorado, Nevada, Oregon, and Washington, a new study by the Insurance Institute for Highway Safety (IIHS) and another by the affiliated Highway Loss Data Institute (HLDI) show.
However, the preliminary results of a separate IIHS study of injured drivers who visited emergency rooms in California, Colorado and Oregon showed that drivers who used marijuana alone were no more likely to be involved in crashes than drivers who hadn’t used the drug. That is consistent with a 2015 study by the National Highway Traffic Safety Administration that found that a positive test for marijuana was not associated with increased risk of being involved in a police-reported crash.
“Our latest research makes it clear that legalizing marijuana for recreational use does increase overall crash rates,” said IIHS-HLDI president David Harkey in a prepared statement. “That’s obviously something policymakers and safety professionals will need to address as more states move to liberalize their laws—even if the way marijuana affects crash risk for individual drivers remains uncertain.”
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More than a third of U.S. states have legalized recreational marijuana for adults 21 and older. The hefty tax revenues those states are earning have others exploring similar legislation, and recent polls indicate that 68 percent of American adults favor legalization. Consumption also appears to be expanding rapidly, with self-reports of past-month marijuana use doubling from 6 percent to 12 percent of those surveyed between 2008 and 2019.
That’s a potential concern for those who care about road safety, according to the group. Driving simulator tests have shown that drivers who are high on marijuana react more slowly, find it harder to pay attention, have more difficulty maintaining their car’s position in the lane, and make more errors