'Doctor, I do not understand the results of the test, because I swear I am not drinking alcohol.' Truth or lie?

Objective Nowadays, alcohol consumption has still been a public health concern that frequently has forensic consequences. The measurement of markers of alcohol consumption or alcohol abuse is thus important to assess alcohol consumption or to confirm alcohol abstinence during the weeks or the months before the sampling, which can be decisive and guide drastically a court decision. Direct alcohol markers, such as ethanol, ethyl glucuronide (EtG) and ethyl sulfate (EtS) in serum, EtG and fatty acid ethyl esters (FAEE) in hair, or phosphatidylethanol (PEth) in blood, are available markers with high specificity and sensitivity [1] . In some particular situations, elevation of the concentration of the marker is not the consequence of alcohol consumption by the patient, but the results of alcohol or marker exposition before sampling [2] . Thus, this could conduct to erroneous interpretation even if the result is not an analytical false-positive case. Recently, we have been confronted to several situations involving presence of PEth in blood of patients denying any alcohol consumption for a couple of months, which led us to look for a possible pitfall. Methods Dried blood spots (10.5 μL) were obtained from three volunteers (two females and one male) after cleaning their hands with soap and water or disinfectant solution containing ethanol (70% or 98%) using Hemaxis® (DBS System SA) kit. The PEth homolog 16:0/18:1 concentration was determined by LC-MS/MS (API 5000 Sciex) according to validated and published method [3] . Results The first volunteer (woman) declared to be teetotaler. PEth blood concentrations after washing her hands with Sterilium® gel [ethanol 85% (w/w)] and ethanol solution [ethanol 98% (v/v)] were 130 ng/mL and 350 ng/mL, respectively. The second volunteer (woman) declared to consume alcohol Conclusion An abnormal elevation of PEth concentration in blood was observed after using ethanolic solution for hand cleaning. Thus, ethyl alcohol disinfection have to be avoid before blood sampling for DBS. If not, a rapid formation of PEth could happen during blood sampling, involving a risk of erroneous interpretation concerning alcohol consumption.