No direct link between cannabis use and traffic accidents


Last Summer, data came out of Colorado reporting that traffic fatalities were near-historic lows. Now, new studies by the National Highway Transportation Safety Administration (NHTSA) seems to show what some have already known: there doesn’t seem to be a link between cannabis use and car accidents.

The Drug and Alcohol Crash Risk Study which looked at 9,000 participants over a 20 month period found that “about 8 percent of drivers during weekend nighttime hours were found to have alcohol in their system, and just over 1 percent were found with 0.08 percent or higher breath alcohol content – the legal limit in every state. This is down by about 30 percent from the previous survey in 2007 and down 80 percent from the first survey in 1973.”

The study confirmed that alcohol use by drivers was clearly associated with elevated risk of crash involvement. A driver with a breath alcohol content (BrAC) above 0.08 was 4 times as likely to have an accident compared to a driver with a lower or no BrAC, and “[d]rivers with alcohol levels at .15 BrAC had 12 times the risk.”

The study found that more drivers tested positive for “illegal drugs,” which includes cannabis, compared to previous studies. A footnote by the NHTSA states, “Despite recent changes in the legal status of marijuana in some States, for simplicity and to allow inter-survey comparisons, this drug remained included within the ‘illegal’ category in the 2013–2014 NRS.” The NHTSA study continues, “Changes in State policy on marijuana use, including medical and recreational use, may have contributed to an increase in marijuana use by drivers. However, the survey does not permit a state-by-state comparison.” The study also does not show the percentage of drivers who only had cannabis in their system, or that the person was actually high at the time they were tested. However, the study found even though drivers “testing positive for THC were overrepresented in the crash-involved (case) population… [W]hen demographic factors (age and gender) and alcohol use were controlled, the study did not find an increase in population based crash risk associated with THC use.” In other words, there is no direct correlation between consuming cannabis and an increased risk of having a traffic accident.

Jeff Michael, NHTSA’s associate administrator for research and program development, said, “These findings highlight the importance of research to better understand how marijuana use affects drivers so states and communities can craft the best safety policies.” I’m certain that some will use this quote without looking at the study results, and then lobby state and local governments to make penalties for possession or use of cannabis more severe; while others will attempt to show the study results to the same legislators in an attempt to lessen or remove the penalties that now exist for possessing or consuming a plant.