Testing for alcohol use in hair: is ethyl glucuronide (EtG) stable in hair?

Abstract

Purpose : Ethyl glucuronide (EtG) is a biological marker in hair used to indicate abstinence or excessive alcohol consumption. The main aim of this paper is to evaluate the stability of EtG in hair samples as it can potentially be affected by normal hygiene, and affect interpretation of the results. Methods : EtG was measured by GC-MS/MS in 102 hair samples, which were sectioned in three monthly sections when available to produce 291 sections of hair (sectioned set) and 468 hair samples (not sectioned set), where the most recent centimetre was analysed. Results : The 95% percentiles of the EtG levels detected in the not sectioned set and in the first section of the sectioned set were 0.23 ng/mg ( N=468 ) and 0.22 ng/mg ( N=102 ), respectively. The 95% percentiles of the levels detected in the second sections and in the third sections were 0.15 ng/mg ( N=102 ) and 0.10 ng/mg ( N=87 ), respectively. Levels were below cut-off (0.01 ng/mg) in 61% in the not sectioned set and 67% in the sectioned set. Of the samples where EtG was detected, the second section samples showed mean EtG levels 74% lower the levels detected in the first section. The mean levels detected of EtG in third section were 62% the levels of the second section and 47% the levels detected in the first section. Analysis of variance showed the levels of the third section significantly lower ( p ) than the first section. Conclusion : The results of this study suggest that normal hair hygiene might wash out EtG from the hair. The recommendation is therefore that only the most recent month must reliably monitor abstinence or chronic alcohol abuse using head hair and that data should be evaluated in conjunction with other biochemical tests and clinical evaluation.