More Than Half of Serious Crashes Involve Drugs, NHTSA Study Suggests

Almost a third of subjects had two or more impairing substances in their system in crashes that seriously injured or killed someone.

byJames Gilboy| PUBLISHED Dec 14, 2022 5:52 PM
More Than Half of Serious Crashes Involve Drugs, NHTSA Study Suggests
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A study this week by the National Highway Traffic Safety Administration found that more than half of serious crashes included detectable psychoactive substances, such as alcohol or other drugs.

Conducted between the NHTSA and third-party researchers, the study gathered data from 7,279 road users processed at seven selected Level 1 trauma centers after being seriously or fatally injured in a crash. Toxicology panels found that 55.8% of study subjects tested positive for psychoactive substances in their systems, with 19.9% testing positive for two or more substances. In fatal crashes, that figure spiked to 32%.

The most common substances detected were THC cannabinoids, the psychoactive components of marijuana, which appeared in 25.1% of those tested. Alcohol placed a close second at 23.1%, with almost 20% of study subjects exceeding the national legal limit of 0.08% blood-alcohol content, according to The Associated Press. (Note that alcohol remains detectable in the blood only half as long as cannabinoids, according to American Addiction Centers, lingering six hours as opposed to cannabinoids' 12.)

Table of toxicology panel results from the NHTSA study. NHTSA

A further 10.8% of subjects tested positive for controlled stimulants (not caffeine), while 9.3% showed up for opioids. Other classes of drugs, such as antidepressants, sedatives, over-the-counter medications, and miscellaneous substances made up smaller proportions of the results. Substance choice was found to correlate with the age and sex of study subjects, as well as the time of day and day of the week of the crash.

Despite suggesting impaired driving trends that NHTSA research psychologist Amy Berning called "a concern," she advised not to read too deeply into the study's results. Berning cautioned that the data pool isn't representative of the whole country, and that subjects were only tested for the presence of certain drugs, not for levels that would indicate impairment. Many drugs in the study, such as methylphenidate, can remain detectable in the body for days, even weeks after its prescribed use. The study also integrated data from injured bicyclists and pedestrians, though it did not control for the design of roads or intersections where crashes occurred, which influence crash severity, according to BMJ Journal.

Still, with 937 people dying in crashes involving impaired drivers in December 2020 alone, the study serves as a timely reminder to stay sober on the road this holiday season.

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