Incidental ethanol exposure from multiple household products: implications for phosphatidylethanol positivity

Phosphatidylethanol (PEth) is a sensitive biomarker of ethanol exposure; however, interpretive ambiguity persists in the 10-19 ng/mL range. Incidental exposure to ethanol-containing products may contribute to low-level PEth formation, but potential additive effects from concurrent exposure have not been systematically evaluated. This study assessed whether hand sanitizer and mouthwash, alone or in combination, influence PEth concentrations.

In this prospective pilot study, 42 adults were assigned to hand sanitizer (70% ethanol, 10 uses/day), mouthwash (21.6% ethanol, 4 uses/day), combined exposure (both mouthwash and hand sanitizer) or control groups for 14 days. Blood samples were collected at baseline, Day 7, and Day 14. PEth 16:0/18:1 (POPEth) was quantified by LC-MS/MS (LLOQ 10 ng/mL; LOD 0.7 ng/mL). Within-group changes were evaluated using paired, one-sided t-tests. Exposure groups were compared with controls using one-sided permutation tests, and combined exposure was compared with individual exposure groups using one-sided Welch two-sample t-tests.

All participants had baseline POPEth concentrations below the LLOQ. No significant increases from baseline or differences from controls were observed in any exposure group (p > 0.05 for all comparisons). Combined exposure did not result in significantly higher POPEth concentrations than either individual exposure (p > 0.05). Small increases above the LOD (≤3 ng/mL) did not approach the LLOQ. No protocol-adherent participants exceeded the LLOQ.

Concurrent exposure did not result in a measurable additive effect on POPEth concentrations under the conditions evaluated. Incidental exposure to these products is unlikely to meaningfully affect interpretation at established clinical decision thresholds; however, larger studies are warranted to confirm these findings.