Marijuana use poses crash risk, but far lower than that of alcohol

By David Tanner, Land Line senior editor | 2/12/2015

Marijuana use increases crash risk by 25 percent over sober driving, a recent study shows, but that pales in comparison with a 400 percent crash risk associated with having a blood-alcohol content of 0.08 – considered the legal limit to drive a passenger vehicle in all U.S. states.

The federal agency that released the study, the National Highway Traffic Safety Administration, says ongoing research is needed to fully understand the effects of marijuana on driving.

The agency notes that a number of crashes in which marijuana was present involved younger males, and that it has been difficult to pinpoint whether it was marijuana or other factors that were to blame.

“The survey found that marijuana users are more likely to be involved in accidents, but that the increased risk may be due in part because marijuana users are more likely to be in groups at higher risk of crashes,” NHTSA stated in a press release. “In particular, marijuana users are more likely to be young men – a group already at high risk.”

Data for the study – actually a pair of studies – came from crash reports and control groups as well as the Roadside Survey of Alcohol and Drug Use by Drivers that NHTSA updates every few years.

The latest edition of the roadside survey shows that alcohol use in drivers has been decreasing since 2007 and is significantly lower than what the first survey found in 1973. Marijuana use, on the other hand, is on the increase, NHTSA says.

NHTSA’s associate administrator for research, Jeff Michael, writes that marijuana and other drugs impair judgment, reaction times and awareness and that the agency will continue to study the effects.

“These findings highlight the importance of research to better understand how marijuana use affects drivers so states and communities can craft the best safety policies,” Michael stated.

Worth noting is that marijuana use remains illegal for operators of commercial vehicles, regardless of state laws regarding personal or medical use. In addition, alcohol use while operating a commercial vehicle carries penalties that could result in disqualification.

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