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DHHS review: dermal PFAS absorption measurable; data gaps hinder numeric guidance
Summary
DHHS told the board that laboratory and skin‑model studies show PFAS can permeate skin and, in high‑concentration or occupational scenarios, dermal uptake may be an important exposure route; DHHS said permeability coefficients vary by model, solvent and pH and there are no federal dermal thresholds for most PFAS.
Kennedy Holt, environmental toxicologist at DHHS’s occupational and environmental epidemiology branch, summarized the literature on dermal PFAS exposures, noting both animal and human‑model work that measured permeability coefficients and serum increases after dermal dosing.
"Studies seem to suggest that dermal absorption may represent an important route of exposure in some scenarios," Holt said, citing the Franco et al. (2012) and Hall et al. (2024) work and a 2025 review that favored studies using physiologically relevant pH and solvents. Holt emphasized uncertainty: permeability coefficients ranged by orders of magnitude across models and solvents (some studies used methanol, others water/acetone), shorter‑chain PFAS sometimes permeated more readily, and most PFAS lack dermal permeability data or regulatory dermal thresholds.
Board members asked whether temperature (for example, hot showers) affects dermal uptake and about variability among PFAS; presenters identified temperature, solvent/pH, and lack of standardized permeability measures as important gaps and said DHHS is drafting qualitative messaging for affected communities while coordinating with DEQ.
Holt said DHHS will track new studies and is open to technical input from board members who wish to review models or datasets.
