Occurrence of hydroxylated polychlorinated biphenyls in the brain of cetaceans stranded along the Japanese coast

Levels of hydroxylated polychlorinated biphenyls (OH–PCBs) and PCBs were measured in the brain of melon-headed whales (MW: Peponocephala electra), striped dolphins (SD: Stenella coeruleoalba) and finless porpoises (FP: Neophocaena phocaenoides) stranded along the Japanese coast during 2002–2003. Levels of OH–PCBs (including identified and unknown OH–P5CB, –H6CB, –H7CB and O8CB congeners) in the brain of MW, SD and FP were in the range of 20–290, 21–330 and 170–240 pg/g wet wt., respectively. Observed OH–PCB levels were 2–3 orders of magnitude lower than PCBs in the same individuals. OH–PCBs/PCBs ratios in MW, SD and FP brain were lower than those in blood of humans and wildlife and in the brain of polar bears reported previously. OH–PCBs were also detected in maternal and fetal brain of SD (1 pair), suggesting transfer of OH–PCBs into the fetal brain of odontocete cetaceans. When fetus/dam concentration ratios of OH–PCB congeners detected in maternal and fetal brain were estimated, the values were higher than those of PCB congeners, implying that OH–PCBs in maternal blood could be more easily transferred into fetal brain via placenta than PCBs.