Human in vitro percutaneous absorption of bisphenol S and bisphenol A: A comparative study

Bisphenol A (BPA) is widely used in industrial products. Due to the toxicity of this compound, and to comply with restrictions and regulations, manufacturers have progressively replaced it by substitutes. One of the main substitutes used is bisphenol S (BPS). Despite increasing use in many products, the effects of BPS on human health have been little investigated, and studies on percutaneous BPS absorption and particularly toxicokinetic data are lacking. However, the endocrine-disrupting activity of BPA and BPS appears comparable. Dermal contact is a significant source of occupational exposure and is the main route during handling of bisphenol-containing receipts by cashiers. Here, percutaneous BPS absorption was investigated and compared to that of BPA. Experiments were performed according to OECD guidelines. Test compounds dissolved in a vehicle - acetone, artificial sebum or water - were applied in vitro to fresh human skin samples in static Franz diffusion cells. Flux, cumulative absorbed dose and distribution of dose recovered were measured. BPA absorption was vehicle-dependent ranging from 3% with sebum to 41% with water. BPS absorption was much lower than BPA absorption whatever the vehicle tested (less than 1% of applied dose). However, depending on the vehicle 20% to 47% of the applied BPS dose remained in the skin, and was consequently potentially absorbable. Both BPA and BPS were mainly absorbed without biotransformation. Taken together, these results indicate that workers may be exposed to BPS through skin when handling products containing it. This exposure is of concern as its toxicity is currently incompletely understood.