Study reveals persistent THC use among fatal crash drivers
A new study presented at the American College of Surgeons Clinical Congress found that nearly 42% of drivers killed in crashes in Ohio had active THC in their blood, with levels far exceeding legal limits. The prevalence remained unchanged even after recreational cannabis legalization in 2023. Researchers urge stronger public messaging on the risks of driving after marijuana use.
Researchers from Wright State University analyzed coroner records from Montgomery County, Ohio, covering January 2019 to September 2024. Of 246 deceased drivers tested for THC following fatal crashes, 103—41.9%—had active delta-9-tetrahydrocannabinol in their systems. The average blood level was 30.7 ng/mL, well above the 2-5 ng/mL impairment thresholds set by most states.
Yearly positivity rates varied from 25.7% to 48.9%, showing no significant decline over the six-year period. Notably, the rate before Ohio's 2023 legalization of recreational cannabis was 42.1%, rising slightly to 45.2% afterward, indicating that policy changes did not reduce risky behavior.
Lead author Akpofure P. Ekeh, MBBS, FACS, a professor of surgery at Wright State University in Dayton, Ohio, expressed surprise at the findings. "I was surprised to see that level," he said. "An average level of 30.7 ng/mL generally means those people must have consumed marijuana at some time close to driving. This isn't about residual use; it's about recent consumption."
Blood samples were drawn within hours of death, providing a reliable indicator of impairment at the time of the crash. Ekeh emphasized the need for better education: "The messaging over the last few years has been just the push towards recreational legalization. The problem is that from a public health standpoint, there has not been enough emphasis on some of the downsides and the dangers that can occur. People should treat smoking marijuana just like they treat alcohol: don't smoke and drive."
The study, titled "Cannabis Prevalence in Drivers Involved in Motor Vehicle Crash Fatalities over a 6-Year Period," was presented as an abstract at the ACS Clinical Congress 2025 in Chicago from October 4-7. Co-authors include Lois Nguapa, BS; Clara Mussin Phillips, BS; and Ann Cardosi, BS, MPH. As an abstract, it has not yet undergone peer review.