Human in vitro percutaneous absorption of bisphenol S: Assessment of the skin reservoir and occlusion effects

Bisphenol S (BPS) was introduced in many industrial and commercial applications as a presumed safer alternative to bisphenol A. However, concerns have been raised surrounding skin absorption and potential persistence of BPS and its related toxic effects in humans. A previous study revealed the likelihood of a reservoir building up in exposed skin. Here, we studied the interactions of BPS solubilized in acetone, ultrapure water, or artificial sebum with freshly excised human skin samples. In vitro tests were performed in static Franz diffusion cells, to explore reservoir and occlusion effects, absorption and metabolism. Most BPS passed through the skin without metabolization - <10% was recovered as glucuronide or sulfate conjugates. Importantly, a substantial amount of BPS persisted in the skin, especially in the stratum corneum. . This reservoir could lead to prolonged diffusion into the body after surface cleaning. Occlusion, that may occur with protective clothing, amplified BPS absorption up to six-fold. These findings have implications for occupational settings, highlighting the persistence of BPS contamination even after washing the skin's surface and the need to ensure protective equipment is correctly maintained and used.