Fingernail and hair ethyl glucuronide as a long-term alcohol biomarker

Alcohol biomarkers are an important alcohol treatment tool to detect past alcohol consumption and to identify alcohol-related medical conditions. Newer alcohol biomarkers such as ethyl glucuronide (EtG) represent a departure from older alcohol biomarkers in their ability to both detect alcohol specifically and minimal levels of alcohol use even days after consumption. We present results from a study that investigated fingernail and hair EtG as a long-term, up to 90-day, alcohol biomarker. The study sample was a representative group of undergraduate college students (N = 606) aged 18 to 25 who completed an online alcohol use survey and provided fingernail and hair clippings in 2010. The Timeline Followback interview was utilized to collect past 90-day daily drinking information in standard drink units. Logistic regression analysis which controlled for age, gender, and race revealed that total number of standard drinks in the past 90 days significantly predicted a positive fingernail EtG test (β = 0.008, p < .001). A second logistic regression analysis which controlled for age, gender, race, and chemical treatment of hair revealed that total number of standard drinks in the past 90 days significantly predicted a positive hair EtG test (β = 0.008, p < .001) while chemical treatment of hair (predominately female students) predicted a reduced probability of a positive hair EtG test (β = -0.512, p = .05). Newer, long-term alcohol biomarkers such as fingernail EtG (hair as a testing backup) may have gender unbiased utility for future inclusion in public health responses to alcohol-related problems.