Investigation and risk assessment of dioxins and dioxin-like PCBs in main aquatic products in market from Shanghai

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Dioxins (polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans, PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) are widespread persistent organic pollutants with high toxicity. Aquatic product is an important source of high-quality protein, and understanding the occurrence and risk of PCDD/Fs and dl-PCBs in aquatic products is of vital significance. In this study, 101 aquatic product samples (including freshwater fish, freshwater shrimp, freshwater crab, sea fish, sea shrimp, sea crab, and ocean mollusk) sold in Shanghai market from 2017 to 2023 were collected and the concentrations of PCDD/Fs and dl-PCBs were analyzed. In general, although the collected samples display high detection rate (15.4 %–100 % for PCDD/Fs and 76.9 %–100 % for dl-PCBs), the pollution levels of PCDD/Fs and dl-PCBs were relatively low in terms of concentrations as well as toxic equivalent (TEQ). Compared with other species, freshwater crabs exhibit higher contamination to PCDD/Fs and dl-PCBs with detection rates of 100 % and the mean TEQ value of 4.008 pg TEQ g−1 ww, which was also at similar or lower level to the existing reports. Besides, the dl-PCBs pollution in sea fish and sea crab is also at relatively high level compared with other species. Furthermore, the PCDD/Fs level in aquatic products is much lower than the dl-PCBs. After the dietary exposure risk assessment, the mean and 95th percentile values of monthly ∑PCDD/Fs + dl-PCBs exposure via aquatic products for Shanghai residents aged ≥ 3 years old were 7.988 and 25.339 pg TEQ/kg bw/month, respectively, lower than the provisional monthly tolerable intake (PTMI, 70 pg TEQ/kg bw/month) set by the JECFA, indicating the acceptable and low exposure risk. This study provides fundamental information about the occurrence characteristics and risk assessment of PCDD/Fs and dl-PCBs in aquatic products, and can act as reference basis for the formulation of control regulations and limit standards of PCDD/Fs and dl-PCBs in aquatic products in China.