Dioxin and PCB Contamination in Chinese Mitten Crabs: Human Consumption as a Control Mechanism for an Invasive Species

The Chinese mitten crab Eriocheir sinensis is an invasive species in North American and northeastern European rivers and estuaries, especially the Thames, England, with the potential to cause considerable ecological and structural environmental damage. The brown meat of sexually ripe mitten crabs is highly prized in far eastern restaurants, suggesting that harvesting for culinary purposes offers a potential population control mechanism. We have analyzed tissues of Thames and Dutch mitten crabs for potentially toxic dietary contaminants, showing that the brown meat contains raised concentrations of dioxins (polychlorinated dioxins and polychlorinated dibenzofurans) and PCBs (polychlorinated biphenyls), organochlorines which are chronic toxins. We have compared estimated daily intakes of these toxins by consumers of meals of mitten crab brown meat against their suggested European Tolerable Daily Intakes (TDI), concluding that a male adult or female beyond child-bearing age could consume several portions per week derived from Thames crabs, but fewer from the Dutch crabs. With a caveat that excessive consumption of mitten crab brown meat could lead to exposures of potential concern, particularly in the case of children and women of child-bearing age, it does appear that the harvesting of mitten crabs from the Thames for culinary use need not be discouraged.