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Occurrences of legacy and emerging per- and polyfluoroalkyl substances in human milk in China: Results of the third National Human Milk Survey (2017-2020).

Per- and polyfluoroalkyl substances (PFAS) are persistent organic pollutants widely contaminated and exposed in humans. China is a major manufacturer and consumer of these chemicals. To characterize the occurrences, geographical variations, temporal trends, and exposure risks of legacy and emerging PFAS in perinatal women and their children in China, 30 PFAS were measured in 100 pooled human milk samples consisting of 3531 individual samples collected from 100 sites in 24 provinces during the 2017-2020 National Human Milk Survey. Linear-perfluorooctanoic acid (L-PFOA, 151 pg/mL) and linear-perfluorooctane sulfonate (L-PFOS, 57.0 pg/mL) were the predominant PFAS in human milk, followed by 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA, 25.9 pg/mL). The geographic variation trend of PFOA was different from PFOS and Cl-PFESA, and a special geographic trend of perfluoropentanesulfonate (PFPeS) was observed. Comparison of National Human Milk surveys from different periods showed a sharp decrease of PFAS exposure in old industrial areas including Shanghai and Liaoning, but higher PFAS exposure observed in Shandong and Hubei indicated a possible domestic shift of PFAS manufacture to these areas. Worldwide comparison of PFAS in human milk indicated high PFOA exposure in China. Risk assessments for mothers and breastfeeding infants showed that PFAS exposure is of concern in China.