Prevalence of Marijuana Involvement in Fatal Crashes: Washington, 2010 – 2014

The purpose of this study was to quantify the prevalence of marijuana involvement in fatal crashes in the state of Washington in years 2010 – 2014 and to investigate whether the prevalence changed after Washington Initiative 502, which legalized recreational use of marijuana for adults aged 21 years and older and also created a new per se limit for driving under the influence of marijuana, took effect on 6 December 2012. The data examined were obtained from the Washington Traffic Safety Commission and comprised a census of all motor vehicle crashes that occurred on public roads in the state of Washington and resulted in a death within 30 days. Statewide, 3,031 drivers were involved in fatal crashes in years 2010 – 2014. Overall, considering both the actual blood toxicology test results and imputed results, an estimated 303 drivers—10.0% of all drivers involved in fatal crashes in Washington between 2010 and 2014—had detectable delta-9-tetrahydrocannabinol (THC) in their blood at or shortly after the time of the crash. There was evidence that the proportion of drivers in fatal crashes who were positive for THC increased after Initiative 502 legalized recreational use of marijuana for adults aged 21 years and older, however, the increase was not immediate and appeared to have begun approximately 9 months after the effective date of Initiative 502. In 2014, the number and proportion of drivers in fatal crashes who were positive for THC were both more than double the averages from the prior four years. Researchers and policymakers should continue to monitor trends in THC presence and concentrations among drivers involved in crashes.

Language

  • English

Media Info

  • Media Type: Digital/other
  • Features: Appendices; Figures; References; Tables;
  • Pagination: 26p

Subject/Index Terms

Filing Info

  • Accession Number: 01603817
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jun 7 2016 11:05AM