Car crashes are up by as much as six percent in CO, NV, OR and WA, compared with neighboring states that haven’t legalized marijuana for recreational use, new research from the Insurance Institute for Highway Safety (IIHS) and Highway Loss Data Institute (HLDI) shows. The findings come as programs to decriminalize marijuana gain traction with citizens in America, and Canada begins allowing recreational use of marijuana this month.
HLDI analysts estimate that the incidence of collision claims per motor vehicle year increased 6 percent following the start of sales of legal marijuana in Colorado, Nevada, Oregon and Washington, compared with the control states of Idaho, Montana, Utah and Wyoming. The analysis is based on collision loss data from January 2012 through October 2017.
“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,” says IIHS-HLDI President David Harkey. “States exploring legalizing marijuana should consider this effect on highway safety.”
California-based MedMen is among the state-licensed cannabis dispensaries operating in the emerging legal-marijuana industry.
n addition to the study states, Alaska, California, Maine, Massachusetts, Vermont and the District of Columbia also allow recreational use of marijuana for adults 21 and older and medical use of marijuana. Another 22 states allow medical marijuana, while 15 more states permit the use of specific cannabis products for designated medical conditions.
Legalization of recreational use is pending in New Hampshire, New Jersey, New York and Pennsylvania. In November, Michigan and North Dakota will hold referendums on marijuana, and Missouri and Utah voters will decide whether to expand medical marijuana laws in their states.
Driving under the influence of marijuana is illegal in all 50 states and D.C., but determining impairment is challenging. Unlike alcohol, the amount of marijuana present in a person’s body doesn’t consistently relate to impairment. THC, or Tetrahydrocannabinol, is the primary psychoactive component of cannabis. A positive test for THC and its active metabolite doesn’t mean the driver was impaired at the time of the crash. Habitual users of marijuana may have positive blood tests for THC days or weeks after using the drug.
Marijuana’s role in crashes isn’t as clear as the link between alcohol and crashes. Many states don’t include consistent information on driver drug use in crash reports, and policies and procedures for drug testing are inconsistent. More drivers in crashes are tested for alcohol than for drugs. When drivers are tested, other drugs are often found in combination with alcohol, which makes it difficult to isolate their separate effects.
“Despite the difficulty of isolating the specific effects of marijuana impairment on crash risk, the evidence is growing that legalizing its use increases crashes,” Harkey says.