Background Perfluoroalkyl substances (PFAS) with their persistence, accumulation, migration, and toxicity are widely found in various water bodies, indicating potential human exposure risk via drinking water.

Objective This study aims to analyze the pollution status of PFAS in drinking water in Shanghai and assess relevant human health risk.

Methods Source water samples were collected from two water sources (A and B) in Shanghai, including the Yangtze estuary water source and the Huangpu River upstream water source. According to water production process, treated water samples were collected from one routine treatment water plant and one deep treatment water plant which both used water source A, as well as from one deep treatment water plant which used water source B. Samples were collected in October 2019 (level period), December 2019 (dry period), and July 2020 (wet period) respectively, with 2 parallel samples from each site, and stored in 1-litre brown polypropylene plastic containers. A total of 23 PFAS were determined by solid phase extraction and ultra high performance liquid chromatography tandem-mass spectrometry. Then the risks of non-carcinogenic chemicals was evaluated by US Environmental Protection Agency (EPA) health risk assessment models.

Results Among the 23 target substances, 14 and 11 kinds of PFAS were detected in all source water and treated water samples (100%), respectively, including perfluorinated carboxylic acid and perfluorinated sulfonic acid; 9 and 12 kinds of PFAS were not detected, respectively, and all were perfluoroamides. The total concentration of PFAS (ΣPFAS) in two types of water was 15.52 to 118.44 ng·L^-1, the highest concentrations of dominant perfluorooctanoic acid (PFOA) and perfluorobutanoic acid (PFBA) were 34.79 and 29.99ng·L^-1, respectively, and the concentrations of PFOA and perfluorooctane sulfonate (PFOS) did not exceed the drinking water threshold (70 ng·L^-1) stipulated by US EPA. The ΣPFAS concentration of water source B was 2.7 times that of water source A. Except the perfluoro-1-nonanesulfonate (PFNS) slightly higher in water source A, the concentrations of detected substances in water source B were significantly higher than those in water source A. The concentration of PFAS in water source A showed little difference in different periods, while that in water source B was shown as dry period > level period > wet period. The PFAS in water source A were removed effectively by water treatment processes, as the removal rate was 21.97% by conventional treatment and 64.29% by deep treatment. The removal effect in water source B was not obvious, and the content of contaminants before and after treatment had little changes. The annual personal excess risks of PFOA and PFOS were lower than the maximum acceptable risk (10^-6 per year) recommended by the International Committee of Radiological Protection (ICRP).

Conclusion There is slight PFAS contamination in Shanghai's drinking water. The annual personal excess risks of PFOS and PFOA via drinking water are low and below the maximum acceptable level recommended by the ICRP.