Alcohol and other drugs of abuse can alter normal behavior in a deleterious way. Epidemiological studies have shown that 50 percent or more of all single-vehicle traffic fatalities in the United States are associated with the use of ALCOHOL. The risk of a driver causing an accident increases progressively the more that BLOOD ALCOHOL CONTENT (BAC) increases past 0.4 grams per liter (g/l). At BACs of 1.0 g/l, the risk is tenfold, and with BACs of 1.5 g/l, the risk is almost thirtyfold compared to nonalcohol conditions. The same phenomenon applies to accidents in which pedestrians are killed by drunk drivers.

Psychomotor Performance

Most behavioral tasks are complex processes in which information sampling and its processing, motor responses, and sensorimotor coordination are involved. A decrement in any part of this system leads to impaired performance. Numerous studies describe techniques...