Reducing illegal blood alcohol limits for driving: effects on traffic safety

Abstract

This chapter provides a scientific review of the evidence regarding the benefits of reducing the illegal blood alcohol concentration (BAC) limit for driving. Numerous independent studies in the United States indicate that lowering the illegal BAC limit from 0.10 to 0.08 g/dL has resulted in 5 to 16 % reductions in alcohol-related crashes, fatalities, or injuries. The illegal limit is 0.05 BAC in numerous countries around the world and several international studies indicate that lowering the illegal per se limit from 0.08 to 0.05 g/dL BAC also reduces alcohol-related fatalities. Laboratory studies indicate that impairment in critical driving functions begins at low BACs and that most subjects are significantly impaired at 0.05 g/dL BAC. The relative risk of being involved in a fatal crash as a driver is four to 10 times greater for drivers with BACs between 0.05 and 0.07 g/dL compared to drivers with 0.00 g/dL BACs. There is strong evidence in the literature that lowering the BAC limit from 0.10 to 0.08 g/dL is effective, that lowering the BAC limit from 0.08 to 0.05 is effective, that lowering the limit from 0.05 to 0.03 or 0.02 g/dL is effective, and that lowering the BAC limit for youth to any measurable amount of alcohol is effective. These law changes serve as a general deterrent to drinking and driving and ultimately save lives. This critical review supports the adoption of lower illegal BAC limits for driving in countries around the world.