Drugs in fatally injured young male drivers.

One or more drugs were detected in 81 percent of 440 male drivers, aged 15-34, killed in motor vehicle crashes in California; two or more drugs were detected in 43 percent. Alcohol, the most frequently found drug, was detected in 70 percent of the drivers, marijuana in 37 percent, and cocaine in 11 percent. Each of 24 other drugs was detected in fewer than 5 percent. Except for alcohol, drugs were infrequently found alone; typically, they were found in combination with high blood alcohol concentrations. The causal role of drugs in crashes was assessed by comparing drivers with and without drugs in terms of their responsibility for the crash. Alcohol was associated with increased crash responsibility; the role of other drugs could not be adequately determined.