CQ



Investigating Changes in Fatal-Crash-Involved Drivers’ Cannabinoid Prevalence after Passage of Medical Marijuana LawsA summary of a time-series investigation of changes in fatal-crash-involved drivers’ cannabinoid prevalence after passage of medical marijuana laws. Project lead author was CA DMV Research Program Specialist, G. Vanine Guenzburger. This summary prepared by Research Manager Patrice Rogers for Florida AAA Summit 1/26/15, accompanies Ms. Guenzburger's project slides. Background: Marijuana use affects critical driving skills and functions such as perception, concentration, decision making, attention, reaction time, and coordination. Research shows that when marijuana is used within four hours of driving, it is associated with from 2 to 6 times higher risk of crashing than drug-free driving. California was the first state in the U.S., to impose a medical marijuana law with implementation of California Proposition 215 (1996). The law, known as the California Compassionate Use Act, was enacted by California voters and took effect on Nov. 6, 1996 as California Health & Safety Code 11362.5. The law allows patients and their designated primary caregivers to possess and cultivate marijuana for personal medical use upon receipt of a recommendation of a California-licensed physician. The initial "popular" law was subsequently operationalized by a legislative bill implemented in 2004 (Senate Bill 420). The new law imposed statewide guidelines outlining how much marijuana could be grown and possessed by patients, and granting state-level legal protections to physicians recommending marijuana and dispensaries selling marijuana. The limits of this law, however, were rendered moot by People V. Kelly (2010) 47 Cal.4th 1008, in which the court ruled that for medicinal use, the amounts of marijuana possessed or cultivated may not be regulated by the state. As of December 2012 medical marijuana laws were implemented in 19 U.S. states and Washington DC. With the increasing number of states introducing medical marijuana laws, we asked: Are the implementations of medical marijuana laws in the states associated with an increase in the number of drivers involved in fatal crashes who tested positive for cannabinoids?Do we find more cannabinoid-positive drivers involved in fatal crashes in those states with easier access to medical marijuana?The prevalence of marijuana use was measured using FARS data to determine the percentage of drivers in each state testing positive for cannabinoids. A correction was applied to account for the vast differences among states regarding their policies/practices for when and under what conditions drug testing is completed had a strong potential to result in different proportions of drivers involved in fatal crashes being actually tested for drugs. Actual marijuana testing was found to increase with passage of each law and now about 40% for all fatal crash drivers in California are tested. The initial law (Proposition 215) did not result in an increase in fatal-crash marijuana-positive prevalence. The subsequent legislation (Senate Bill 420), that operationalized the state’s implementation of the medical marijuana law was found to be associated with a significant step increase in marijuana prevalence. There was no indication that the law’s impact was tied to an increasing trend in use over time. California’s prevalence of marijuana use has generally been higher than that of other states, and may remain higher; however, this study found that national trends are increasing while California’s prevalence plateaued following the immediate increase following Senate Bill 420. Of all the states assessed, Only 3 showed significant immediate increased use after the implementation of a medical marijuana law: California, Hawaii and Washington. Those are the states that have also generally tested higher percentages of drivers involved in fatal crashes for drugs than do other states. Each state was ranked on an accessibility-to-marijuana scale. However accessibility was not found to correlate with findings of higher prevalence. California was ranked # 1 in access to marijuana; but the biggest increase in marijuana prevalence was found in Hawaii, which ranked # 8 on the study's scale.Limiting the analysis to only California dead drivers, resulted in larger increases in cannabinoid prevalence following the laws. Assessing only dead drivers in each of the states showed the same pattern as before, with similarly larger step increases in each state. Conclusions:Time series evaluations showed that among the 13 states that introduced medical marijuana laws during this study period, immediate increased marijuana use was found in only three States: California, Hawaii, and Washington, but not an overall increasing trend, Having greater or easier access to marijuana did not result in a statistically significant increase in cannabinoids prevalence following implementation of medical marijuana laws. Variability in policies related to drug testing of drivers involved in fatal crashes in U.S. States might explain why this association was not found in other States. Together, these findings suggest that the number of drivers interested in obtaining and using marijuana for medical use only, may be limited, and a state's increase in prevalence following laws strictly limited to allowing medicinal use will generally result in smaller more immediate increases rather than gradual but increasing trends. Recommendations:Similar study should be made in states passing laws that allow greater "recreational" use. Drug testing policies and procedures for drivers involved in fatal crashes should be standardized and more consistent across the U.S. States. Further investigations should continue to examine the relationship between crash risk and marijuana use among drivers involved in fatal crashes. Preliminary findings in a current DMV study show evidence that drivers in fatal crashes that test positive for marijuana exhibit somewhat greater risky behavior just prior to crashing than do those that test negative. (These study results should be available later this year.)Contact Information:Patrice Rogers, DMV Research and Development Branch—DUI Unit ManagerPatrice.rogers@dmv., or G. Vanine Guenzburger, Gloriam.Guenzbuger@dmv. ................
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