Background Per- and polyfluoroalkyl substances (PFAS) are globally concerning environmental endocrine disruptors, with prominent pollution issues in China, and have been widely detected in humans. Diet, especially animal-derived foods such as aquatic products, is the main source of PFAS.

Objective To investigate the contamination of PFAS in local aquatic products in Shanghai that reported high PFAS exposure, evaluate PFAS exposure through aquatic products and drinking water, and perform risk assessments for individuals of different age groups in Shanghai, providing evidence for dietary recommendations for Shanghai residents and risk management of PFAS in China.

Methods Four aquatic product species, including freshwater fish (n=28), marine fish (n=27), shrimps (n=18), and crabs (n=17), were purchased from randomly selected sampling sites in 16 districts and counties of Shanghai. The concentrations of 13 PFAS congeners were measured, including 3 short-chain perfluoroalkyl carboxylic acids (PFCAs), 5 long-chain PFCAs, 2 short-chain perfluoroalkyl sulfonic acids (PFSAs), and 3 long-chain PFSAs. The assessment of local residents' exposure risk to PFAS was conducted by combining their consumption of aquatic products and drinking water with the most widely concerned three PFAS congeners (perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), and perfluorononanoate (PFNA) in both average consumers and high consumers. Hazard index was applied to evaluate human health risks according to the oral minimal risk levels (MRL) of PFAS established by Agency for Toxic Substances and Disease Registration (ATSDR) and the tolerable weekly intake (TWI) established by European Food Safety Authority (EFSA).

Results Nine to ten PFAS congeners were positive in each of the four aquatic product species out of the 13 PFAS congeners, and the most frequently positive PFAS congeners were PFOS and five long-chain PFCA (the positive rates were > 50%). The highest concentration of Σ₁₃PFAS (median) was detected in crabs 6.314 ng·g⁻¹ (wet weight, thereafter), followed by shrimps (2.313 ng·g⁻¹), freshwater fish (0.833 ng·g⁻¹), and marine fish (0.808 ng·g⁻¹). The distribution of PFAS congeners varied in four aquatic food species: freshwater fish and marine fish showed the leading median concentrations of PFOS (0.238 and 0.145 ng·g⁻¹), respectively, while shrimps and crabs showed the leading median concentrations of perfluoroundecanoate (PFUA) (0.840 and 1.439 ng·g⁻¹), respectively. The average daily intake of Σ₃PFAS through aquatic products and drinking water by average consumers ranged from 0.145 to 1.129 ng·kg⁻¹·d⁻¹ (in terms of body weight, thereafter), and by high consumers from 1.129 to 2.939 ng·kg⁻¹·d⁻¹, respectively. Adults (>18 years) and children (<12 years), especially those under 9 years old, were more likely exposed to PFAS, and PFOS contributed the most across all age groups. According to the MRL established by ATSDR, there was no health risk for average consumers of all ages in Shanghai hazard index (HI) <1, but there were health risks for all ages in high consumers except for adults (HI>1). Meanwhile, after comparing with the more stringent TWI formulated by EFSA, there were health risks for all ages in both average consumers and high consumers in Shanghai: HI for average consumers was from 1.17 to 2.46, and HI for high consumers from 3.56 to 6.09.

Conclusion In Shanghai, PFAS is frequently detected in aquatic products. In general, PFOS concentrations are higher than those of other PFAS congeners. The PFAS levels of four aquatic food species from high to low are crabs, shrimps, freshwater fish, and marine fish. Potential health risks are found in local residents, especially adults and young children (less than 9 years old), via aquatic products and drinking water, and aquatic products are the primary source. It is recommended to optimize the types of aquatic products consumed to reduce the risk of PFAS intake for the local population.