Urinary profiles of bisphenol S derivatives and their exposure pathway analysis in maternal and infant populations of Beijing

Bisphenol S (BPS) derivatives have potential reproductive developmental toxicity and have been found in the environment and in breast milk. The level of infant exposure and the source are currently unknown. In this study, we investigated BPS and six derivatives (together referred to as BPs) in urine samples from mothers and infants, indoor dust, breast milk and infant formula in Beijing, China. BPS, diphenyl sulfone (DPS) and 4-allyloxy-4'-hydroxydiphenyl sulfone (BPS-MAE) were the main BPs. Notably, the concentration of DPS in infants' urine was higher than that of BPS, which warrants attention. Infants have higher daily intake levels than mothers. Exclusively breastfed infants have a higher risk of BPs exposure than exclusively formula-fed infants. For exclusive breastfed infants, the contribution of individual BPs through breast milk was 23.2% to 93.6%. While for exclusively formula-fed infants, the contribution of individual BPs through infant formula was 30.5% to 70.3%. The contribution of individual BPs through indoor dust was no more than 10%. The results suggesting that infants can be exposed to BPs through other pathways. This is the first comprehensive assessment of maternal and infants exposure to BPS derivatives, providing insights into the sources of infant exposure.