Citation

Huestis MA. Clin. Chem. 2015; 61(10): 1223-1225.

Copyright

(Copyright © 2015, American Association for Clinical Chemistry)

DOI

10.1373/clinchem.2015.245001

PMID

unavailable

Abstract

Cannabis, the most common illicit drug identified in motor vehicle crashes, had a higher prevalence than alcohol in drivers' blood or oral fluid specimens in the US in the 2013-2014 National Roadside Study (1). In fact, the percentage of weekend nighttime drivers with measureable Δ9-tetrahydrocannabinol (THC)2 in blood or oral fluid increased to 12.6%, a 48% increase since 2007 (2). Cannabis use is increasing since the legalization of cannabis in 4 US states and the approval of medical cannabis in 23 US states and many countries. The incidence of THC-impaired driving increased in Washington state from 19.1% before to 24.9% after cannabis legalization (3). These statistics highlight an important public health and safety concern: cannabis-impaired driving.

In this issue of Clinical Chemistry, for the first time, Andrews et al. compare cannabinoid blood concentrations in fatal road traffic collision (RTC) victims with non-RTC victims in London and southeast England from 2011 to 2013 (4). Drivers' postmortem cannabinoid concentrations were reported previously from driver culpability studies (5), comparing the prevalence of cannabinoid-positive biological samples in culpable drivers to those not judged culpable for the crash. However, blood cannabinoid concentrations in postmortem non-RTC victims from the same population base are rarely available.

Controlled human cannabinoid administration data, on-the-road driving data after cannabinoid administration, and epidemiological data provide evidence of cannabis's effects on driving. Two recent metaanalyses (6, 7) showed an approximate 2-fold risk of a motor vehicle collision after cannabis intake, and my group recently reported significant cannabis impairment of lateral driving control with and without low-dose alcohol (8).

Authentic postmortem drug concentrations are needed for evaluating drug crash risk, but there are many difficulties in obtaining these data...


Keywords: Cannabis impaired driving

Language: en