Methods for Determining Blood Alcohol Concentration: Current and Retrospective

This chapter provides an overview of the methods of determining Blood Alcohol Concentration (BAC) that are useful in alcohol research. BAC refers to the amount of alcohol circulating in the bloodstream, and is the best estimate of the effects of alcohol on the brain. BAC varies as a function of dose of alcohol, time, gender, body weight, age, beverage type, and individual differences in absorption and metabolism of alcohol. BAC measurement allows for a direct comparison of intoxication levels across persons. Although direct blood alcohol measurement via gas chromatographic methods remains the standard, BAC can be estimated from other bodily fluids, including saliva, urine, and sweat, and from the breath samples. In addition, predictions can be made using mathematical models of BAC that take into account major factors affecting the absorption and metabolism of alcohol. Both advantages and disadvantages of each method of BAC determination are reviewed. Limitations relate both to the biological correspondence of the sample tested to the actual BAC and to the current instrumentation available for analysis. When choosing among BAC measurement options, the resources available, the level of accuracy required, and the nature of the inferences to be made, must be considered.