Investigation and risk assessment of PCDDs, PCDFs, and dl-PCBs in Chinese mitten crab (Eriocheir sinensis) from the South Dongting lake area, China

Dioxins are among the common persistent organic pollutants in crabs. To clarify the potential risk of dioxins pollution in Chinese mitten crab, eight types of samples were collected in the South Dongting Lake area for the analysis of 17 PCDD/Fs and 12 dl-PCBs. The results indicate that the concentration of Σ PCDD/Fs and Σ dl-PCBs in crabs was between 0.993–10.8 and 35.0–282 pg/g w.w., respectively. The mean WHO-TEQ value of Σ PCDD/Fs in crabs was 0.248 ± 0.205 pg TEQ/g w.w., and the mean WHO-TEQ value of Σ PCDD/Fs+dl-PCBs in crabs was 0.359 ± 0.280 pg TEQ/g w.w.. The total toxic equivalent of bottom sediment, surrounding soil, crab brown meat and juvenile crab were relatively high, which were 2.88, 2.67, 1.50 and 1.30 pg TEQ/g w.w., respectively. In the case of 99th percentile, the WHO-TEQ values of Σ PCDD/Fs and Σ PCDD/Fs+dl-PCBs in crab white meat were all within the maximum permitted levels as specified in commission regulation (EU) 2023/915. The HQ values of 99th percentile of Σ PCDD/Fs+dl-PCBs were 0.0783, 0.00703 and 0.0853 for eating brown meat products, eating white meat products and eating whole crabs, respectively. The coordinate points of the samples are connected to the origin by a straight line in the correspondence analysis map. The angle formed by the straight lines of crab brown meat/crab white meat and juvenile crab was acute angle, as did the feed. The angles between the straight line of bottom sediment/surrounding soil and that of other samples were all obtuse angles. In conclusion, although the dioxins of bottom sediment and surrounding soil are obvious, the dioxins of adult crabs are mainly related to that of the juvenile crabs and feed. At present, the intake of dioxins from Chinese mitten crab by Chinese residents is at a safe level because of low annual consumption. It is recommended that adults limit their weekly crab consumption to 1–4 crabs, or only 23.1–105 g of crab brown meat per week, or solely 435–1242 g of crab white meat per week.