Synonyms

Blood alcohol concentration; Blood alcohol content

Definition

Measure of alcohol in the blood.

Current Knowledge

Blood alcohol level (BAL) is typically expressed as milligrams or grams of ethanol per deciliter (e.g., 100 mg/dL or 0.10 g/dL). A level of 20–30 mg/dL typically results from the ingestion of one to two drinks. One drink corresponds to 340 mL (12 oz.) of beer, 115 mL (4 oz) of wine, and 43 mL (1.5 oz) of a shot. Blood alcohol levels as low as 20–80 mg/dL can lead to decreased inhibitions and decreased cognitive and motor performance, while levels of 300–400 mg/dL can lead to coma or death. Blood alcohol levels typically correlate inversely with cognitive and motor performance (i.e., as blood alcohol levels increase, cognitive and motor performance decrease). Specifically, increased blood alcohol levels correlate with slower reaction time and inversely correlate with frontal executive function. The tendency to underestimate one’s own blood alcohol level seems to pose an additional risk of impairment and injury risk. Additionally, speed of cognitive performance recovers as alcohol is metabolized and BAL decrease; however, accuracy may continue to remain impaired.

Cross-References