According to the National Survey on Drug Use and Health, over 10 million people age 12 or older are estimated to have driven under the influence of illicit drugs in 2008 and marijuana is the most commonly detected non-alcohol drug in drivers. This has caused many to question the role of marijuana in causing car accidents.
To answer this question, a team of researchers at Columbia University lead by Dr. Guohua Li, professor of epidemiology, did a meta-analysis of nine epidemiologic studies of drugged driving. They found that drivers who test positive for marijuana or who report using marijuana are more than twice as likely as other drivers to be involved in motor vehicle crashes. The researchers also found evidence that crash risk increases with the concentration of marijuana-produced compounds in the urine and the frequency of self-reported marijuana use.
Full study findings are published online in Epidemiologic Reviews.
While the results of the study show a compelling association between car accidents and marijuana use, they are not quite complete. More research needs to be done to completely understand the relationship between the two. Just because there is a strong association, it does not necessarily mean causation. Dr. Guohua Li commented on his own study saying, “if the crash risk associated with marijuana is confirmed by further research, this is likely to have major implications for driving safety and public policy. It also would play a critical role in informing policy on the use of medical marijuana.”
This study could in fact have a large impact on future policies regarding marijuana’s legal status and driving safety. Many states have become increasingly lenient with marijuana regulations, making it easier to grow, possess or consume and some have even legalized medical marijuana. Combine this with the ongoing epidemic of drug-impaired driving in our country and you can see how this study could influence some serious policy changes. Some highway safety advocates are already worried about the results of the study and are looking for ways to reduce the risks and keep the roads safe.