Fatty Acid Ethyl Esters in Hair as Markers of Alcohol Consumption. Segmental Hair Analysis of Alcoholics, Social Drinkers, and Teetotalers

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Abstract
Background: Fatty acid ethyl esters (FAEEs) are products of nonoxidative ethanol metabolism. After incorporation in hair, they should be suitable long-term markers of alcohol abuse. Methods: Hair samples from 19 alcoholics in a treatment program, 10 fatalities with verified excessive alcohol consumption, 13 moderate social drinkers who consumed up to 20 g ethanol/day, and 5 strict teetotalers were analyzed in 1–12 segments for four FAEEs (ethyl myristate, ethyl palmitate, ethyl oleate, and ethyl stearate) by external degreasing with n-heptane, extraction with a dimethyl sulfoxide-n-heptane mixture, headspace solid-phase microextraction of the extracts, and gas chromatography-mass spectrometry with deuterated internal standards. The n-heptane washings were analyzed in the same way for FAEEs from the hair surface. Results: The sum of the four ester concentrations in hair calculated for the proximal 0–6 cm segment was 2.5–13.5 ng/mg (mean, 6.8 ng/mg) for the fatalities, 0.92–11.6 ng/mg (mean, 4.0 ng/mg) for 17 of the alcoholics in treatment, 0.20–0.85 ng/mg (mean, 0.41 ng/mg) for the moderate social drinkers, and 0.06–0.37 ng/mg (mean, 0.16 ng/mg) for the teetotalers. In almost all cases the segmental concentrations increased from proximal to distal. There was no agreement between the self-reported drinking histories of the participants and the FAEE concentrations along the hair length. Ethyl oleate was the dominant ester in all samples. Conclusions: FAEEs are deposited in hair mainly from sebum. Despite large individual differences, FAEE hair concentrations can be used as markers for excessive alcohol consumption with relatively high accuracy.