Case study: Is bisphenol S safer than bisphenol A in thermal papers?

The Risk Assessment Committee of the European Chemical Agency released a scientific opinion alerting that the risk associated with dermal occupational exposure to bisphenol A (BPA) via thermal paper might not be adequately controlled because the estimated exposure was around twice the Derived No Effect Level (DNEL) and the European Commission will effectively restrict BPA in thermal paper as soon as 2020. Bisphenol S (BPS) is currently being used as a BPA surrogate and is already widespread in thermal paper receipts. Based on publically available information in the scientific literature, we assessed the risk associated with dermal BPS exposure via thermal paper for the general and occupational populations to compare with BPA situation. We developed two exposure scenarios; one based on the total excreted BPS and another on exposure estimations by transferring BPS from the thermal paper matrix to skin. Both scenarios yielded similar exposures for the general population (0.016-0.013 µg/kg bw/day), but the exposure estimated for the workers in the second scenario (0.96 µg/kg bw/day) was around 17-fold higher than that estimated for the workers in the first scenario. The systemic DNELs for the general and workers populations were 0.45 and 0.91 µg BPS/kg bw/day, respectively, which were 4.6- and 19-fold higher than the respective dermal DNELs. Risk Characterisation Ratio (RCR) (estimated exposure through urinary excretion compared with the systemic DNEL) in the first and most reliable scenario suggested that the risk was adequately controlled. In the second scenario, however, the RCR suggests that the risk might not be adequately controlled for both the general population and workers. This work raises the necessity of generate more toxicodynamic and toxicokinetic information, specially using dermal exposures, to properly assess the risk associated to dermal BPS exposure because the situation might presumably get worse after 2020.