Percutaneous absorption of two bisphenol a analogues, BPAF and TGSA: Novel In vitro data from human skin

Bisphenol AF (BPAF) and TGSA are analogues of Bisphenol A (BPA). BPAF is used in polymer synthesis, while TGSA is applied in thermal papers. The EU classifies BPAF as toxic to reproduction and TGSA as a skin sensitizer. However, TGSA's other health effects remain unclear. BPAF contamination has been noted among electronic waste workers, and TGSA exposure is documented in various professions. Despite the significance of skin contact, data on skin permeation rates for BPAF and TGSA are limited. This study aimed to generate percutaneous absorption data for BPAF and TGSA following OECD guidelines. [14C]-labeled BPAF or TGSA was applied to human skin samples in vitro using Franz diffusion cells for 20 and 40 h, respectively. Key parameters such as steady-state flux, lag time, and skin permeability coefficient (K_p) were calculated. Furthermore, the distribution of the dose across different compartments, particularly within the skin, was evaluated at the conclusion of the experiment. Sequential strippings and epidermis-dermis separation were conducted for BPAF to predict the potential absorption of the remaining dose present within the skin. The permeability coefficients for BPAF and TGSA were found to be 1.9 E-03 and 1.6 E-03 cm/h, with 22% and 23% of the applied doses absorbed, respectively. Both chemicals are classified as "fast" penetrants based on their K_p values. These findings suggest that BPAF and TGSA are absorbed through the skin, highlighting potential occupational risks through dermal exposure. The new percutaneous absorption data will enhance the assessment of the occupational risks.