Many contaminants in the meat from crayfish heads

The meat from the heads of crayfish contains a high level of contaminants, including heavy metals, dioxins and polychlorinated biphenyls, or PCBs. However, the meat in the tail of the crustacean has a much lower level of contaminants, according to Wageningen University environmental research center WENR.

The researchers said it was clearly better to only use crayfish tails when eating the meat from the animal. A standard must be established for the maximum level of contaminants that may be in the heads of crayfish sold for consumption, the scientists argued.

Though not a native species to Dutch waterways, crayfish are an invasive exotic species that causes a great deal of nuisance. They are also captured at a large scale. Since 2010, harvested crayfish may be offered for consumption. Crayfish caught in the Netherlands are for sale at some catering wholesalers, and a number of restaurants have the crustaceans on their menus.

Until now, it was not known whether eating crayfish from the Netherlands entailed any health risks. The animals absorb contaminants found in water beds and bottoms into their bodies.

WENR researchers examined crayfish from 22 locations across the country for heavy metals, PCBs, dioxins and PFAS. All metals were found in both the heads and tails of the animals. According to the researchers, this is not surprising, since all metals also occur naturally in aquatic sediments. But the level of dioxins and PCBs was much higher in the head meat than in the tail meat.

This is because these substances accumulate in fat-rich tissues and organs, which are located in the heads of crayfish. The majority of PFAS contamination was also found in head meat.

Tail meat is muscle meat, and European standards apply to it. Meat from crayfish tails almost always remained below the limits ​​stated in European rules. The researchers strongly recommend also setting standards for brown head meat, as it is still served and eaten despite having much higher contamination levels.