The significance of the accumulation of cadmium by aquatic organisms.

Cadmium, by virtue of its toxicity, persistence, and bioaccumulation appears on the "black list" of all the international conventions aimed at protecting the aquatic environment from pollution. Although there is no doubt that cadmium is both persistent and toxic to aquatic life at relatively low concentrations, its bioaccumulation potential appears to have been somewhat exaggerated. Median concentration factors for both marine and freshwater organisms are less than 100 times and for vertebrate (fish) species concentration factors are less than 20 times. There is no evidence in the literature for biomagnification of cadmium and bioconcentration is only likely to be of significance in a restricted range of gastropod mollusks and some crustacea.