The influence of molecular structure on the retention and excretion of polychlorinated biphenyls by the mouse

Abstract

Di-, tetra-, penta-, and hexachlorinated biphenyls (PCBs) have been administered to mice, and their retention in fat has been measured 7 and 21 days after dosing. One penta- and two hexachlorobiphenyls were labeled with 14C, and the fecal excretion of radioactivity by mice dosed with these bore a close relation to their retention in body fat. The rate of loss of PCBs from fat was found to be influenced by the presence and location of unsubstituted pairs of carbon atoms in the molecule. With an unsubstituted pair in the 3,4-position loss from fat was fairly rapid and not much affected by the orientation of chlorine substituents. A more rapid loss from fat was observed when the unsubstituted pair was in the 2,3-position, but this was greatly diminished by chlorines in the 2,2′- or 2′,2′-positions. This inhibition of the loss of PCBs from fat by o-chlorines was less marked with one chlorine in the 2′-position, and was completely absent with three chlorines in the 2,2′,2′-positions.