Fatty acid ethyl ester concentrations in hair and self-reported alcohol consumption in 644 cases from different origin

Abstract

For diagnosis of chronic alcohol abuse, fatty acid ethyl esters (FAEE) were determined in hair samples from 644 individuals, mainly parents from child protection cases. The analysis for ethyl myristate, ethyl palmitate, ethyl oleate and ethyl stearate was performed according to a validated procedure consisting of external degreasing by two times washing with n-heptane, extraction with a mixture of dimethylsulfoxide and n-heptane, separation and evaporation of the n-heptane layer, headspace solid phase microextraction of the residue after addition of phosphate buffer pH 7.6 and gas chromatography–mass spectrometry using deuterated internal standards. For interpretation, the sum of the concentrations of the four esters C FAEE was used with the cut-off's 0.5 ng/mg for the proximal scalp hair segment 0–3 cm or less and 1.0 ng/mg for scalp hair samples with a length between 3 and 6 cm and for body hair. C FAEE ranged from 0.11 to 31 ng/mg (mean 1.77 ng/mg, median 0.82 ng/mg). The mean concentration ratio between the 4 esters was 8:45:38:9. 298 cases had C FAEE above the cut-off's. Self-reported drinking data were obtained in 553 of the cases in the categories abstinent (156 cases), moderate drinking (252 cases) and excessive drinking (145 cases). Median and box-plot data clearly demonstrate differentiation of these ingestor sub-populations by C FAEE. However, in the abstinent and moderate groups the consumption was frequently underreported (37 and 110 cases positive) whereas in the group self-reported excessive drinking 32 cases were negative. Comparison of C FAEE with carbohydrate-deficient transferrin (CDT) in 139 cases and gamma-glutamyltransferase (GGT) in 136 cases showed a good agreement in CDT- and GGT positive cases (27/28 and 32/41) but a large portion of the negative CDT- and GGT-results with positive hair test (44/100 and 48/95) which is explained mainly by the much shorter time window of CDT and GGT. No significant correlation was found between persons weight and C FAEE showing that the test is not biased against physical fitness or obesity. Furthermore, there was no statistically significant difference between scalp hair (541 samples) and hair from other body sites (84 samples). In conclusion, FAEE in hair appeared to be suitable markers for the detection of excessive drinking. However, as there is no proportionality between drinking amount and C FAEE, the additional use of other markers can increase the reliability of the interpretation.