AURORA, Colo. – The proportion of marijuana-positive drivers
involved in fatal motor vehicle crashes in Colorado has increased dramatically
since the commercialization of medical marijuana in the middle of 2009, according
to a study by University of Colorado School of Medicine researchers.
data from the National Highway Traffic Safety Administration’s Fatality
Analysis Reporting System covering 1994 to 2011, the researchers analyzed fatal
motor vehicle crashes in Colorado and in the 34 states that did not have
medical marijuana laws, comparing changes over time in the proportion of
drivers who were marijuana-positive and alcohol-impaired.
researchers found that fatal motor vehicle crashes in Colorado involving at
least one driver who tested positive for marijuana accounted for 4.5 percent in
the first six months of 1994; this percentage increased to 10 percent in the
last six months of 2011. They reported that Colorado underwent a
significant increase in the proportion of drivers in a fatal motor vehicle
crash who were marijuana-positive after the commercialization of medical
marijuana in the middle of 2009.
The increase in Colorado was
significantly greater compared to the 34 non-medical marijuana states from
mid-2009 to 2011. The researchers also reported no significant changes
over time in the proportion of drivers in a fatal motor vehicle crash who were
alcohol-impaired within Colorado and comparing Colorado to the 34 non-medical
Salomonsen-Sautel, PhD, who was a postdoctoral fellow in the Department of
Pharmacology, is the lead author of the study, which is available online in the
journal Drug and Alcohol Dependence. Christian Hopfer, MD, associate professor
of psychiatry, is the senior author.
Salomonsen-Sautel said the study raises important concerns about the increase in the proportion
of drivers in a fatal motor vehicle crash who were marijuana-positive since the
commercialization of medical marijuana in Colorado, particularly in comparison
to the 34 non-medical marijuana states. While the study does not determine
cause and effect relationships, such as whether marijuana-positive drivers
caused or contributed to the fatal crashes, it indicates a need for better
education and prevention programs to curb impaired driving.
researchers from the School of Medicine who are authors of the study are
Sung-Joon Min, PhD, Joseph T. Sakai, MD, and Christian Thurstone, MD. The study
was funded by the National Institute on Drug Abuse and the National Institute
on Alcohol Abuse and Alcoholism.
at the University of Colorado School of Medicine work to advance science and
improve care. These faculty members include physicians, educators and
scientists at University of Colorado Hospital, Children’s Hospital Colorado,
Denver Health, National Jewish Health, and the Denver Veterans Affairs Medical
Center. The school is located on the Anschutz
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