Spatial distribution of bisphenol S in surface water and human serum from Yangtze River watershed, China: Implications for exposure through drinking water

Bisphenol S (BPS) is an emerging environmental contaminant. The occurrence of this compound in humans and the environment is not well described. In this study, 120 surface water samples and 240 human serum samples were collected along the Yangtze River in 2015 for the determination of the occurrence of BPS. Surface water and human serum samples were extracted by solid phase extraction and liquid-liquid extraction, respectively, and analyzed by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). BPS was detected in all river water samples at concentrations that ranged from 0.18 to 14.9 ng/L (median: 0.98 ng/L), with higher concentrations in spring than summer. The median estimated daily intake (EDI) of BPS through water ingestion by infants in spring and summer was 0.12 and 0.06 ng/kg body weight (bw)/day, respectively. BPS was detected in human serum with the highest concentrations in samples from Nanjing (median: 0.65 ng/mL, maximum: 169 ng/mL) among the four cities studied. No significant gender related difference in BPS concentrations was observed in human sera, while higher concentrations were found in younger individuals than elderly. The EDI of BPS calculated based on serum concentrations of adults in Nanjing was 22.8 ng/kg bw/day. Ingestion of water accounted for