Blood Alcohol Content (BAC), sometimes referred to as Blood Alcohol Level (BAL) is the percent of alcohol present in the blood. There are various means of determining BAC. An absolute level can be obtained only by drawing a sample of blood. The most reliable estimate can be obtained via very accurate breathalyzers that take a sample of alveolar (deep lung) air. These are often used by police departments, and are considered legal evidence in a court of law. Handheld breathalyzers are less accurate, and while they are not considered legal evidence of intoxication, they can be used by police to determine probable cause to obtain a BAC that is considered legal evidence in a court of law.

Factors that affect BAC

  • Body Mass – A larger body allows alcohol to be distributed over greater area, and thus the lower concentration of alcohol.
  • Percent Body Water – Alcohol is soluble in water, but not in fat. Thus, if you have a lower body fat percentage and are more physically fit, you will have a lower BAL for your weight.
  • Sex – Females tend to have a higher body fat ratio to men and they have less of an enzyme called alcohol dehydrogenase, which aids in the ability to metabolize alcohol.
  • Metabolism – While the elimination rate for alcohol is relatively similar for all people, it is affected by genetics.
  • Food - Consuming food before and while drinking slows absorption by slowing stomach emptying.
  • Medications/Drugs- Certain medications interact with alcohol and cause your BAL to rise faster or more than normal. Be careful and always read the label.

Considering these factors, we can only estimate BAC/BAL. To learn more about how to stay in the Party Positive Zone (BAL of 0.00-0.06), contact Hokie Wellness for educational materials related to Blood Alcohol Level.