Reference Values for the Alcohol Biomarker Phosphatidylethanol (PEth) in the Belgian Population: Insights from a Nationwide Microsampling Study

Background Phosphatidylethanol 16:0/18:1 (PEth) is a well-established direct biomarker for monitoring recent and chronic alcohol consumption. However, population-based surveys assessing PEth in both people who drink alcohol and people who do not drink alcohol remain limited, despite their value for contextualizing forensic and clinical results. Methods PEth was quantified in samples collected during the 2022-2023 Belgian National Food Consumption Survey (n=487) using capillary volumetric absorptive microsampling (VAMS) and an ISO17025-accredited liquid chromatography-tandem mass spectrometry method (10-2000 ng/mL). Participants also completed an AUDIT-C questionnaire; relationships with PEth were evaluated using Spearman correlation and Cohen’s kappa. Weighted data were used to derive estimates for the general Belgian population and compared with two presumed higher-consumption subgroups. Results PEth concentrations in the general Belgian population ranged from <10 to 1400 ng/mL. Overall, 35.7% had concentrations between 20-200 ng/mL and 10.7% exceeded 200 ng/mL. PEth correlated strongly with AUDIT-C scores, with Spearman’s rank correlation coefficients of 0.61 in males and 0.64 in females. Agreement between PEth and AUDIT-C for identifying hazardous drinking was moderate in males and substantial in females (Cohen’s kappa: 0.55 and 0.63, respectively). The median PEth concentration in the general population was 17 ng/mL (95% CI: 15-18), compared with 32 ng/mL in a non-abstinent adult population and 122 ng/mL in individuals enrolled in a driver’s license regranting program. Conclusion These findings provide population-based PEth reference data for Belgium and demonstrate clear differences in PEth distributions between general and higher-exposure populations, supporting improved contextual interpretation of forensic and clinical PEth results.