What is EtPa alcohol testing?

What is EtPa alcohol testing? How accurate is it compared to other alcohol testing methods? We answer these questions in our latest expert guide…

Head hair alcohol testing works by looking at two markers of alcohol: ethyl glucuronide (EtG) and a fatty acid ethyl ester (FAEE) called ethyl palmitate (EtPa). The level of alcohol consumed will determine the level of these markers in the hair. Both types of markers are absorbed via different routes and their levels can assist in assessing excessive alcohol use by an individual.

The reasons that both EtG and EtPa markers are analyzed is because they are affected by external factors in different ways. EtG is produced by the liver and incorporated into the hair, mainly through sweat. It is hydrophilic, meaning that it is water soluble. As such, some EtG may be lost through the use of hair dye and excessive hair washing. EtPa is produced in the blood and incorporated into hair via sebum (an oily substance secreted by glands in the skin). FAEEs are lipophilic and therefore not water soluble, so although not affected by hair washing, the amount of EtPa detected could be affected by use of hairsprays, gels and wax.

Ideally, the minimum length of hair for EtG and EtPa tests is a 3 cm section taken from nearest the scalp, around 200 individual strands (about the width of a pencil). This is consistent with the consensus on hair alcohol testing for chronic excessive alcohol consumption published by the Society of Hair Testing (SoHT) in June 2009. The result will be considered either above or below the recommended SoHT cut-off levels. The level of biomarker found in the hair can help determine if a person has been drinking chronically and excessively, and will show an overview of 3 or 6 months.