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Traffic Fatalities Decline in States With Medical Marijuana Laws

Summary: Researchers report an average of an 11 percent reduction in traffic fatalities in states after enacting medical marijuana laws.

Source: Columbia University.

Most affected are those between the ages of 25 and 44.

States that enacted medical marijuana laws, on average, experienced reductions in traffic fatalities, according to a study by researchers at Columbia University’s Mailman School of Public Health. Overall, states that passed medical marijuana laws saw an 11 percent reduction in traffic fatalities, on average, after enacting the laws, and had 26 percent lower rates of traffic fatalities compared with states without the laws. The findings are published online in the American Journal of Public Health.

Reductions in traffic fatalities greatly impacted those between the ages of 15 and 44 and were especially striking among those aged 25 to 44 years, a group representing a high percentage of those registered patients for medical marijuana use.

Specifically, the researchers observed an 11 percent reduction of among those aged 15 to 24 years, 12 percent for ages 25 to 44, and 9 percent for those 45 years and older. Operational dispensaries were also associated with a significant reduction in traffic fatalities in those aged 25 to 44 years at 5 percent.

Lacking was strong evidence suggesting reductions among those aged 45 years and older, which is also a group overrepresented in the population of patients registered in state medical marijuana programs. “This finding suggests that the mechanisms by which medical marijuana laws reduce traffic fatalities mostly operate in those younger adults, a group also frequently involved in alcohol-related traffic fatalities,” said Julian Santaella-Tenorio, a doctoral student in Epidemiology at the Mailman School of Public Health. In 2004 and 2013, 47 percent of fatally injured drivers with a blood alcohol content of 0.08 or greater were 25 to 44 years old.

The researchers based their findings on data for 1985-2014 from the Fatality Analysis Reporting System, a nationwide census of traffic fatalities information maintained by the National Highway Traffic Safety Administration. The association between medical marijuana laws and traffic fatalities for drivers, passengers, cyclists, and pedestrians was examined for each state enacting the laws. They also evaluated the link between marijuana dispensaries and traffic fatalities. Overall, a total of 1.22 million deaths were attributed to traffic crashes occurring in the 50 states during the study period.

Not all states with medical marijuana laws experienced reductions in traffic fatality rates, and a few states actually experienced increases. In California, after an initial immediate reduction of 16 percent in traffic fatalities and in New Mexico, after an immediate post-law reduction of 17.5 percent, the laws were actually associated with gradual increases in fatality rates. “These findings provide evidence of the heterogeneity of medical marijuana laws and indicate the need for further research on the particularities of implementing the laws at the local level. It also indicates an interaction of medical marijuana laws with other aspects, such as stronger police enforcement, that may influence traffic fatality rates,” noted Santaella-Tenorio.

Image shows a medical marijuana sign.

Reductions in traffic fatalities greatly impacted those between the ages of 15 and 44 and were especially striking among those aged 25 to 44 years, a group representing a high percentage of those registered patients for medical marijuana use. NeuroscienceNews.com image is for illustrative purposes only.

“It is also possible that states with medical marijuana laws and lower traffic fatality rates may be related to lower levels of alcohol-impaired driving behavior in these states,” noted Silvia Martins, MD, PhD, associate professor at the Mailman School and senior author. “We found evidence that states with the marijuana laws in place compared with those which did not, reported, on average, lower rates of drivers endorsing driving after having too many drinks. We can also point to other characteristics such as the strength of public health laws related to driving, infrastructure characteristics, or the quality of health care systems, as a partial explanation for these findings.”

“The evidence linking medical marijuana laws and traffic fatalities lays the groundwork for future studies on specific mechanisms,” said Santaella-Tenorio. “We also expect another area of study will be the association between the laws and nonfatal traffic injuries.”

About this neuroscience research article

Co-authors are Christine M. Mauro, Melanie M. Wall, June H. Kim, Katherine M. Keyes, and Deborah S. Hasin–all of the Mailman School of Public Health; Magdalena Cerdá, University of California, Davis; and Sandro Galea, Boston University.

Funding: This work was supported by the National Institute on Drug Abuse (grants R01DA037866, R01DA034244, T32 DA031099, K01 DA030449), the New York State Psychiatric Institute; and the National Institute on Alcohol Abuse and Alcoholism (grant K01 AA021511). Dr. Santaella-Tenorio is funded by the J. William Fulbright and the Colciencias doctoral scholarships.

Source: Stephanie Berger – Columbia University
Image Source: NeuroscienceNews.com image is in the public domain.
Original Research: Full open access research for “State Medical Marijuana Laws and the Prevalence of Opioids Detected Among Fatally Injured Drivers” by June H. Kim, Julian Santaella-Tenorio, Christine Mauro, Julia Wrobel, Magdalena Cerdà, Katherine M. Keyes, Deborah Hasin, Silvia S. Martins, and Guohua Li in American Journal of Public Health. Published online November 2016 doi:10.2105/AJPH.2016.303426

Cite This NeuroscienceNews.com Article
Columbia University “Traffic Fatalities Decline in States With Medical Marijuana Laws .” NeuroscienceNews. NeuroscienceNews, 20 December 2016.
<http://neurosciencenews.com/medical-marijuana-traffic-accidents-5788/>.
Columbia University (2016, December 20). Traffic Fatalities Decline in States With Medical Marijuana Laws . NeuroscienceNew. Retrieved December 20, 2016 from http://neurosciencenews.com/medical-marijuana-traffic-accidents-5788/
Columbia University “Traffic Fatalities Decline in States With Medical Marijuana Laws .” http://neurosciencenews.com/medical-marijuana-traffic-accidents-5788/ (accessed December 20, 2016).

Abstract

State Medical Marijuana Laws and the Prevalence of Opioids Detected Among Fatally Injured Drivers

Objectives. To assess the association between medical marijuana laws (MMLs) and the odds of a positive opioid test, an indicator for prior use.

Methods. We analyzed 1999–2013 Fatality Analysis Reporting System (FARS) data from 18 states that tested for alcohol and other drugs in at least 80% of drivers who died within 1 hour of crashing (n = 68 394). Within-state and between-state comparisons assessed opioid positivity among drivers crashing in states with an operational MML (i.e., allowances for home cultivation or active dispensaries) versus drivers crashing in states before a future MML was operational.

Results.
State-specific estimates indicated a reduction in opioid positivity for most states after implementation of an operational MML, although none of these estimates were significant. When we combined states, we observed no significant overall association (odds ratio [OR] = 0.79; 95% confidence interval [CI] = 0.61, 1.03). However, age-stratified analyses indicated a significant reduction in opioid positivity for drivers aged 21 to 40 years (OR = 0.50; 95% CI = 0.37, 0.67; interaction P < .001).

Conclusions. Operational MMLs are associated with reductions in opioid positivity among 21- to 40-year-old fatally injured drivers and may reduce opioid use and overdose.

“State Medical Marijuana Laws and the Prevalence of Opioids Detected Among Fatally Injured Drivers” by June H. Kim, Julian Santaella-Tenorio, Christine Mauro, Julia Wrobel, Magdalena Cerdà, Katherine M. Keyes, Deborah Hasin, Silvia S. Martins, and Guohua Li in American Journal of Public Health. Published online November 2016 doi:10.2105/AJPH.2016.303426

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