A MODEL FOR THE BIOACCUMULATION OF CHLOROBIPHENYL CONGENERS IN MARINE MAMMALS

The behaviour of chlorobiphenyls in marine mammals is best described by a pharmacokinetic model where the blood acts as the central transport compartment between the external environment and a number of peripheral organs, each maintaining a dynamic balance with the concentrations in the blood. Thus, blood samples can be a useful tool in monitoring programmes of chlorobiphenyl concentrations. Differences in the chlorobiphenyl patterns between seals and fish could be explained by the structure-biotransformation relationship developed in an experimental study. A harbour porpoise (Phocoena) seemed also able to metabolize chlorobiphenyl congeners with vicinal hydrogen atoms in the meta and para positions and two ortho-Cl atoms. Because the ratios between persistent and metabolizable congeners differed between specimens, it was not possible to derive 'dioxin type' toxic equivalents from concentrations of congeners occurring at much higher concentrations by calculation of their ratios.