A woman is detained by a U.S. Customs and Border Protection officer after marijuana was found in her vehicle while entering into the United States from Mexico in San Ysidro, California, on September 23, 2016.
HLDI analysts estimate the frequency of collision insurance claims rose a combined 6 percent following the start of retail sales of recreational marijuana in the four mentioned states - in comparison with claims in Idaho, Montana, Utah and Wyoming.
Since the retail sales of marijuana began in Colorado, Nevada, Washington, and Oregon, HLDI researchers estimated that collision claims per insured vehicle went up 6 percent in a combined-state analysis based on data from January 2012 to October 2017.
The rates of vehicle crashes are up by as much as six per cent in Colorado, Nevada, Oregon and Washington where recreational weed is legal, compared to their neighboring states, according to a new report released Thursday by the Institute for Highway Safety (IIHS) and Highway Loss Data Institute (HLDI).
A separate 2017 study from the American Journal of Public Health found that legalized recreational marijuana did not have a significant increase on the number of fatality crashes, however. In Recreational weed went on the market in OR in October 2015, and in Nevada in July 2017. "Law enforcement needs additional tools and advanced training to detect impaired drivers before they crash, regardless of the impairing drug they're using".
"The new IIHS-HLDI research on marijuana and crashes indicates that legalizing marijuana for all uses is having a negative impact on the safety of our roads", said IIHS-HLDI President David Harkey. Those are likely to improve as more states legalize the stuff, but until then, it's still hard to draw a 100-percent link between marijuana use and crashes.
"We know a lot of states are considering making recreational marijuana available", Harkey said. Many states don't include consistent information on driver drug use in crash reports, and policies and procedures for drug testing are inconsistent. THC can remain in a person's bloodstream for weeks after using.
The studies do, however, mention that the role of cannabis in these accidents isn't clear as drivers who test positive for drugs are often found with alcohol in their system as well. Twenty-two more states allow medical marijuana.
"The bottom line of all of this is that we're seeing a consistently higher crash risk in those states that have legalized marijuana for recreational purposes", Harkey said.