In the liver, ethanol is conjugated by uridine diphosphate-glucuronosyltransferase and sulfotransferase enzymes to produce ethyl glucuronide (EtG) and ethyl sulfate (EtS), respectively (Figure 4). Although these metabolites represent less than 0.5% of the ingested alcohol dose, they are relatively stable and persist in body fluids and tissues. After moderate drinking, EtG and EtS remain detectable for ~ 25 hours in blood, several days in urine, and EtG can be detected for weeks to months in hair, making them sensitive and specific biomarkers for recent alcohol consumption (127, 128). Incidental exposure to ethanol (e.g., mouthwash, hand sanitizer) can yield positive urinary EtG and EtS results, so an appropriate analytical cutt-off and combining results from different biomarkers is essential (128).
