Studying the bioaccumulation of chemicals in aquatic organisms: PCBs in fish

PCBs are mixtures of chlorinated biphenyls with different degrees of chlorination, are hydrophobic chemicals, very persistent and bioaccumulative in aquatic organisms, especially in fishes that are at the end of the food chain and are the final receptors of toxicants. PCBs can be classified as narcotics: they produce no change in the biophase and elicit anesthetic reversible effects. Bioaccumulation in fish can occur through the food chain (biomagnification) and through partitioning between the water environment and the fish body (bioconcentration) and depends both from the physicochemical properties of the chemicals and on the morpho-physiological characteristics of the fish. All the PCBs residues in aquatic organisms arise from human activity in that they are not present in the natural environment and can be used as an index of human impact on ecosystems. Here we study the bioaccumulation in fish of PCB 1254 and 1260 for different concentrations in the water of two polluted creeks inside the Oak Ridge Reservation (USA). The study is carried out using an uptake model, FGETS [1] that considers both bioconcentration and biomagnification. The results are validated with measures of bioaccumulation in the fish species under study, C. commersoni, and with its distribution in the water body, highly influenced by bioaccumulation of PCBs. The results obtained demonstrated how powerful is the modelling approach to study bioaccumulation of hydrophobic chemicals in fish and to evaluate the magnitude of human impact on natural environment.