Quantitative benefit and risk assessment of cadmium and nutrient levels in Chinese mitten crab (Eriocheir sinensis)

The use of Chinese mitten crabs for human consumption is controversial due to their uptake of heavy metals, such as cadmium (Cd). We developed a formula for quantification of benefit and risk assessment (hazard quotient) for the intake of a product containing essential polyunsaturated fatty acids versus heavy metals. A total of 70 samples (2100 individuals) of crabs were collected from 6 representative basins in Jiangsu province to determine Cd levels. Cd levels ranged from 0.028 to 5.015 mg kg(-1), and the levels among the basin regions were similar (p > 0.05). To determine the nutritional differences between crabs fed with iced trash fish and formulated feed, we conducted a comparative aquaculture experiment. We simulated the cultivation conditions of crabs in China and found that the nutritional content in the trash fish group (28.724 +/- 2.301 mg kg(-1)) was significantly higher than in the formulated food group (19.278 +/- 3.556 mg kg(-1);p < 0.05). The differences in the hazard quotient of benefit and risk balance between these two diets were not significant (p > 0.05). The average hazard quotient of iced trash fish feed culture was 0.023 +/- 0.019, compared with the formulated feed culture (0.034 +/- 0.028). Formulated feed and iced trash fish produce similar results as culture food for the Chinese mitten crab. In terms of cadmium exposure risk, the appropriate daily consumption of crabs is less than eight. These data can help justify culture using formulated food and the sustainable development of the Chinese mitten crab industry.