Dermal permeation of perfluoroalkyl substances in human skin – An in-vitro study

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous, persistent environmental contaminants, posing significant health risks to animals and humans. While dermal exposure to PFAS through daily contact with consumer products such as school uniforms and personal care items is common, the mechanisms and extent of skin uptake remain poorly understood. This study investigated the dermal penetration of 30 PFAS, both as mixtures and individual compounds, using in vitro human skin models in a Franz Diffusion Cell system. Results showed that in a mixture, short-chain PFAS, including FBSA, PFBA, PFPrS, and PFPeA, demonstrated permeation rates of 4.8 ± 2.5 %, 3.7 ± 0.3 %, 2.0 ± 0.1 %, and 1.1 ± 0.1 %, respectively, over 24 h. In contrast, none of the long-chain PFAS penetrated the skin in the same period. When tested individually in water, FBSA exhibited the highest permeation, achieving 7.0 ± 0.9 % (p < 0.05), underscoring its ability to cross the stratum corneum under simulated environmental conditions. These findings highlight that while permeation of long-chain PFAS could be slowed down by the skin barrier, certain short-chain PFAS, such as FBSA, can penetrate human skin in vitro. This study provides crucial preliminary data on PFAS dermal absorption, emphasizing the need for standardized experimental conditions that account for the chemical properties of PFAS and the physiological properties of human skin. Our findings suggest that further research is needed to elucidate the mechanisms of PFAS dermal absorption and better assess the risk of dermal exposure to PFAS.