• The legalization of marijuana is an idea that is gaining momentum in the United States.  But there may be a dark side to pot becoming more commonplace, an insurance in marijuana traffic fatalities.

    A recent study has determined that fatal motor vehicle collisions involving marijuana use have tripled over the past 10 years.  The study from Columbia University’s Mailman School of Public Health report, found that one in nine drivers involved in fatal crashes test positive for marijuana.  According to Dr. Guohua Li, director of the Center for Injury Epidemiology and Prevention at Columbia, and co-author of the study, “If this trend continues, in five or six years non-alcohol drugs will overtake alcohol to become the most common substance involved in deaths related to impaired driving.”

    The conclusions of the study were based on crash statistics from six states that routinely perform toxicology tests on drivers involved in fatal motor vehicle collisions: California, Hawaii, Illinois, New Hampshire, Rhode Island and West Virginia. The data included over 23,500 drivers who died within one hour of a collision between 1999 and 2010.

    The study found that alcohol contributed to about the same percentage of traffic fatalities during the same time period.  However, drugs played a gradual increasing role in fatal collisions.  Marijuana proved to be the main drug involved in the increase, contributing to 12 percent of 2010 traffic fatalities compared with 4 percent in 1999.  Overall, drugged driving accounted for more than 28 percent of traffic deaths in 2010, up from just over 16 percent in 1999.  According to the researchers, the increase in marijuana use occurred across all age groups and in both sexes.

    Authors of the study noted that the combined use of alcohol and marijuana dramatically increases a driver’s risk of death.  “If a driver is under the influence of alcohol, their risk of a fatal crash is 13 times higher than the risk of the driver who is not under the influence of alcohol,” Li said. “But if the driver is under the influence of both alcohol and marijuana, their risk increases to 24 times that of a sober person.”

    In an endnote to the study, the researchers acknowledged several limitations with their conclusions.  One is that marijuana can be detected in the blood up to one week after use. Therefore, “the prevalence of nonalcoholic drugs reported in this study should be interpreted as an indicator of drug use, not necessarily a measurement of drug impairment.”

    Source: Trends in Alcohol and Other Drugs Detected in Fatally Injured Drivers in the United States, 1999–2010, American Journal of Epidemiology, Jan. 2014.


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