Fish-eating birds metabolism

Although fish-eating birds possess the ability to metabolize CACs, the relative amounts of metabolites found in their tissues is lower than that observed in marine mammals. Apparently their metabolic capacity is less than that of pinnipeds and probably also less than that of some cetaceans. Cetaceans, in turn, have a lower metabolic capacity than pinnipeds and may therefore be more at risk. 

Walker, C.H., 1990. Persistent pollutants in fish-eating sea birds Bioaccumulation, metabolism and effects. Aquat. Toxicol. 17, 293-324. 

Borlakoglu J.T., Wilkins J.P.G., Walker C.H. (1988) Polychlorinated biphenyls in fish-eating sea birds molecular features and metabolic interpretations. Mar. Environ. Res. 24, 15-19. 

Birds and mammals exposed to PCB mixtures frequently react differently. PCBs generally elicit large-colloid goiters in birds these goiters are inherently different from hyperplastic goiters produced in mammals exposed to PCBs. Fish-eating seabirds, such as the razorbill (Alca torda), can rapidly metabolize PCB congeners that have at least one pair of adjacent unsubstituted metapara combinations in the biphenyl moiety. Razorbills metabolized 4-chlorobiphenyl to 4-chloro-4 hydroxybiphenyl however. 

---