Does the use of legal marijuana in the United States create higher rates of car accidents?
More cases of automobile crashes have been reported among states where marijuana has been legalized, according to a first-of-a-kind study conducted by an insurance institute.
In states such as Oregon, Washington, and Colorado, the link between legalized marijuana and higher rates of car accidents reveal a 3 percent increase in collision frequencies, researchers from the Highway Loss Data Institute (HLDI) found.
"We're concerned about what we're seeing," said HLDI senior vice president Matt Moore. "We see strong evidence of an increased crash risk in states that have approved recreational marijuana sales."
Link Between Legal Marijuana, Car Accidents
In 2012, Washington and Colorado became the first two states to approve legalized recreational marijuana. Retail stores in Colorado opened in 2014, while stores in Washington followed suit a year later. As of writing, eight states have legalized the sale of recreational marijuana.
In the study conducted by HLDI, researchers found that between January 2012 and October 2016, accident claims increased by 4.5 percent in Oregon, 16 percent in Colorado, and 6.2 percent in Washington. Insurance industry groups have been closely monitoring accident claims since 2013.
Although the increasing number of car accidents could not be directly linked to the use of marijuana, the study explained that there is a strong correlation between the two.
Causation is difficult to prove because there is no sobriety test specifically designed for marijuana users. With that in mind, researchers point to road construction, distracted driving, and increased driving miles as other factors for higher car crash rates.
Driving While High
More drivers have admitted that they use marijuana, but past research on the impact of driving while high remain inconclusive, experts said. However, a study published in April 2017 found that driving under the influence of drugs is more fatal than drunk driving.
A report in 2014 by Colorado's transportation department revealed that 84 out of 864 drivers who were involved in fatal car accidents tested positive for marijuana, while more than third of 488 fatal crashes involved alcohol.
"Worry that legalized marijuana is increasing crash rates isn't misplaced," said David Zuby, an executive from Insurance Institute for Highway Safety, a nonprofit organization closely affiliated with HLDI.
Zuby added that the findings on cases in Oregon, Washington, and Colorado should provide other states "eyeing legalization pause."
Meanwhile, the HLDI is planning to conduct more of these studies and has started a large-scale case-control research in Oregon to determine whether legalized marijuana use is causing automotive injuries.