Blood Phosphatidylethanol Concentrations Following Regular Exposure to an Alcohol-Based Mouthwash

Direct biomarkers of ethanol are used to monitor individuals who are required to abstain from ethanol consumption. In recent years, blood phosphatidylethanol (PEth) has gained acceptance in clinical and forensic contexts as an abstinence marker. Its elimination half-life of several days provides a window of detection of days to weeks. However, there is no research addressing the extent of PEth formation related to extraneous ethanol exposures. To assess the degree of ethanol absorption and subsequent formation of blood PEth related a common extraneous exposure, regular use of an ethanol-containing mouthwash, we recruited 16 participants to gargle with an alcohol-based mouthwash (21.6% ethanol) 4 times daily, for 12 consecutive days. Blood was analyzed for PEth 16:0/18:1 by liquid chromatography-tandem mass spectrometry. Our hypothesis that blood PEth concentrations would not equal or exceed 20 ng/mL was confirmed. Although the data suggest that regular use of mouthwash is unlikely to result in suprathreshold PEth concentrations, this work highlights the importance of considering extraneous ethanol exposures in clinical decision-making and in future research.