Antemortem toxicological and behavioral findings of drivers involved in fatal traffic crashes: a comparative analysis...

Alcohol/drug-related impairment and unsafe driving behaviors such as speeding, running red lights, or failure to wear a seat belt have been identified as contributing factors to road traffic accidents. This study aims to examine antemortem toxicological testing results, driving behaviors and other characteristics of drivers involved in fatal traffic crashes, which may offer insights into the broader spectrum of fatal crash risk factors.

Toxicological results and case data including demographic characteristics and driving behaviors were analyzed for drivers charged in fatal traffic crashes and thus potentially culpable between 2019 and 2024. These individuals were compared with drivers involved in fatal collisions who had not been charged. Whether a driver was charged with an accident depended not only on culpability but also on the availability of sufficient evidence, the presence of criminal negligence, legal/procedural considerations, contributory faults, and other contextual factors. All drivers survived the accidents and provided antemortem blood samples, which were submitted by the Houston Police Department (HPD) for alcohol and drug testing to the Houston Forensic Science Center (HFSC).

Based on offense classifications in the HFSC database, HPD reports, and court records, 116 drivers were identified as suspects charged in fatal crashes in 2019-2024. Among the charged drivers, 81% were male with an average age of 32 years (range: 17-62), and 97% tested positive for alcohol and/or drugs. Ethanol was the most frequently detected substance (73%), followed by cannabinoids (47%) and cocaine/metabolites (12%). Common unsafe driving behaviors included speeding/failure to control speed (53%), lane deviation (31%), and running red lights/stop signs (20%). In comparison, of 87 uncharged drivers (82% male, average age 40 years) involved in fatal crashes, 61% tested negative for both alcohol and drugs. Among the 39% who tested positive, cannabinoids (17%) and ethanol (9%) were the most frequently detected drugs. The majority (91%) of the charged drivers committed one or more traffic infractions. Failure to control speed/speeding was the most common (53%), followed by failure to drive in a single lane (31%). In contrast, the majority (64%) of the uncharged drivers did not commit a traffic infraction.

The present research revealed several risk factors of fatal traffic crashes - younger male drivers with high blood alcohol concentrations, drug-impaired drivers who failed to control speed or to drive in a single lane, pedestrians who did not yield the right of way to vehicle, and motorcyclists who sped. Targeting these risk factors could aid in addressing the increasing number of traffic fatalities.