Hair follicle testing is a method used to detect drug and alcohol use over an extended period. While widely employed for detecting various substances, the detection of alcohol consumption through this method is less direct than for other drugs. The primary target of hair follicle testing for alcohol is not ethanol itself, but rather a metabolite called ethyl glucuronide (EtG). EtG is formed in the body after alcohol consumption, and a portion of it is deposited in hair follicles.
The ability to detect EtG in hair provides a longer detection window compared to blood or urine tests, potentially revealing alcohol use spanning several months. This capability is particularly valuable in legal contexts, such as child custody cases, probation monitoring, and workplace compliance, where historical patterns of alcohol consumption are relevant. However, the interpretation of EtG results can be complex, requiring careful consideration of factors such as the individual’s metabolism, hair color, and potential external contamination from alcohol-containing products.