Drug Use among Drivers

Glauz, William D.; Blackburn, R. R. (Robert R.) · 1975 · ROSA P / United States. National Highway Traffic Safety Administration

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Summary

This 1975 report by the Midwest Research Institute, commissioned by the National Highway Traffic Safety Administration (NHTSA), investigates the prevalence of drug use among drivers and its association with fatal crash risk. Motivated by the established link between alcohol and traffic fatalities, the study aimed to determine if other drugs—such as sedatives, stimulants, and narcotics—pose a similar threat. The research sought to compare drug incidence in living drivers against data from fatally injured drivers to calculate the relative risk of fatal involvement for drug users. The methodology involved roadside surveys in Lincoln, Nebraska, and Dade County (Miami), Florida. Researchers stopped randomly selected motorists at sites and times corresponding to previous fatal crashes. Participants provided breath, urine, blood, and lip swab samples. Of approximately 1,500 motorists stopped, 78% cooperated with the interview, and 1,029 urine and 840 blood samples were analyzed for 41 specific drugs. Marijuana use was assessed via lip swabs. These findings were compared with data from 710 fatally injured drivers collected in 36 other communities under a prior contract. The results indicated that approximately 3% of Lincoln drivers and 2% of Dade County drivers had detectable levels of drugs in their blood or urine (Level A findings). When including trace amounts (Level B), about 4.3% of drivers in each group tested positive. Sedatives, particularly phenobarbital, were the most commonly detected substances. Lip swabs revealed marijuana traces in 3% of Lincoln drivers and 9% of Dade County drivers. In contrast, drug prevalence was significantly higher among fatally injured drivers, with 10.7% showing Level A findings and 17.6% showing any drug presence. The study concluded that drivers using drugs are approximately four times more likely to be fatally injured in a vehicular crash than non-users. This risk appeared highest for stimulants and antidepressants, though sample sizes limited definitive conclusions. Marijuana users also showed a fourfold increase in fatal crash risk. The report reaffirmed alcohol as the leading causative factor in fatal crashes, noting that drivers with a blood alcohol concentration of 0.10% or higher faced a drastically elevated risk. The authors cautioned that comparisons between living and fatally injured drivers were limited by geographic differences and small sample sizes, but the data strongly suggested that drug use significantly impairs driving safety.

Key finding

Drivers using drugs were found to be about four times as likely to be fatally injured in a vehicular crash as nonusers.

Methodology

on_road

Sample size: 1160

Provenance

The full processing record for this entry. Every stage of this paper's journey through the pipeline is logged — what ran, with which tool and model, how many attempts it took, and when it last completed. Discovered via bulk_ingest_rosap on 2026-05-23 (6 acquisition events logged).

Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.

Topics

Ranked by relevance to this paper. Hover a topic for its definition.

• illicit drugs
• polydrug
• prescription meds
• dui enforcement
• cannabis
• incidence prevalence

Information type

What kind of knowledge this paper contributes, grouped by family — independent of topic (what it is about) and method (how it was studied).

• Empirical Findings: observational prevalence
• Methodological Resource: dataset resource