Comparative aspects of congener specific PCB metabolism.

Despite the large number of PCB congeners identified (in some environmental samples more than 70 isomers and congeners) only some 12 of them account for 80% of the total PCB adipose tissue burden. These compounds are a selective group of PCBs which are highly chlorinated or alternatively lack meta-para-vicinal protons. Comparison of the persistent and non-persistent PCB congeners between human adipose tissue, human breast milk and fish-eating sea birds revealed similarities in the bioaccumulation pattern. These findings suggest a certain inability of cytochrome P-450 mono-oxygenases to metabolise a specific group of PCBs.