Study: Cannabis Least Likely Substance To Elevate Vehicle Crash Risk

The presence of various controlled substances in blood is associated with an increased risk of fatal crash involvement, according to data published online in the journal Accident Analysis and Prevention.

Investigators at Columbia University conducted a case-control study to assess the association between drug use and fatal crash risk. Of the substances identified by researchers, authors reported that depressants were most likely to be associated with crash risk (estimated odds ratio = 4.83). Estimated odds ratios for other specific drug categories were 3.57 for stimulants, 3.41 for polydrug use (excluding alcohol), and 3.03 for narcotics. Marijuana (1.83) possessed the lowest odds ratios of the substances identified.

The odds ratio for cannabis is similar to that reported in a 2012 meta-analysis of 66 separate studies which estimated that cannabis was associated with a nominally increased risk of accident (estimated odds ratio = 1.25). In that study, anti-histamines (1.12) and penicillin (1.12) were associated with comparable odds to cannabis.

Previous studies assessing fatal crash risks have reported far higher odds ratios for alcohol. According to a 2004 study published in the journal Epidemiology, drivers who self-reported consuming two or more alcoholic drinks in a six-hour period prior to driving were nearly eight times more likely to suffer a car crash-related injury compared to non-drinkers.

While Columbia researchers did not assess the risk of alcohol consumption alone, they did report that the use of alcohol in combination with controlled substances increased subjects’ risk of fatal accident more than 20-fold.

For more information, please contact Paul Armentano, NORML Deputy Director, at:paul@norml.org. Full text of the study, “Drug use and fatal motor vehicle crashes: A case-control study,” appears in Accident Analysis and Prevention.

Anthony Martinelli

Anthony is co-founder and Editor-in-Chief of TheJointBlog. He has worked closely with numerous elected officials who support cannabis law reform, including as the former Campaign Manager for King County (WA) Councilmember Dave Upthegrove. He has been published by multiple media outlets, and is a former contributor for Village Voice Media.