ACS: THC Positivity Detected in More Than 40 Percent of Deceased Drivers in Motor Vehicle Crashes

However, six-year analysis shows no change in THC positivity after legalization

By Lori Solomon HealthDay Reporter

THURSDAY, Oct. 9, 2025 (HealthDay News) — More than four in 10 drivers who die in motor vehicle collisions (MVCs) test positive for active delta-9-tetrahydrocannabinol (THC) in their system, according to a study presented at the annual meeting of the American College of Surgeons, held from Oct. 4 to 7 in Chicago.

Lois Nguapa, from Wright State University in Dayton, Ohio, and colleagues studied deceased drivers from MVCs in a single county over six years to determine the prevalence of THC, effect of legislation, and association with other drugs. The analysis included coroner records from Montgomery County, Ohio, for 246 deceased drivers who were tested for THC following a fatal crash from January 2019 to September 2024.

The researchers found that 41.9 percent of drivers tested positive (yearly range, 25.7 to 48.9 percent). Among those testing positive, the mean THC level was 30.7 ng/mL, exceeding most state impairment limits. Before and after legalization, there was no difference in THC positivity rates (42.1 versus 45.2 percent). There were no associations between THC positivity and a patient’s sex or use of two or more other drugs (e.g., alcohol, cocaine, opioids, or amphetamine).

“The messaging over the last few years has been just the push towards recreational legalization,” lead author Akpofure P. Ekeh, M.B.B.S., also from Wright State, said in a statement. “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.”