Relationships between polychlorinated biphenyls and health status in harbor porpoises (Phocoena phocoena) stranded in the United Kingdom

To investigate possible relationships between polychlorinated biphenyl (PCB) exposure and infectious disease mortality in harbor porpoises (Phocoena phocoena) in United Kingdom waters, summed blubber concentrations of 25 chlorobiphenyl congeners (Sigma25CB) in healthy harbor porpoises that died of acute physical trauma (mainly by-catch; n = 175) were compared with Sigma25CB values in animals that died of infectious disease (n = 82). The infectious disease group had significantly greater Sigma25CB values (mean, 27.6 mg/kg lipid) than the physical trauma group (mean, 13.6 mg/kg lipid; p 0.55). These findings are consistent with a causal (immunotoxic) relationship between PCB exposure and infectious disease mortality, and they provide a framework for future quantitative risk-assessment analyses of porpoise populations of known size and PCB exposure