Polychlorinated Biphenyls and Reproductive Hormones in Female Polar Bears at Svalbard

摘要

High concentrations of polychlorinated biphenyls (PCBs) in polar bears from Svalbard have increased concern for that population's reproductive health. We examined whether there were associations between the plasma concentrations of PCBs and reproductive hormones [progesterone (P_4) and 17β-estradiol (E_2)] in free-living female polar bears from Svalbard. Concentrations of P_4 depended on reproductive status, and concentrations were lowest in females with off-spring―females with cubs and females with yearlings. In these females, the P_4, concentrations were positively correlated with plasma ΣPCBs (sum of all analyzed polychlorinated biphenyl congeners) concentrations. The ΣPCBs concentrations explained 27% of the variation in the P_4 concentrations. There were no correlations between ΣPCBs and E_2 and cortisol in any of the groups of polar bears, or between ΣPCBs and P_4, in single polar bears. Although the ΣPCBs―P_4 relationship in female polar bears with offspring is not evidence per se of a direct cause-effect association, the results indicate that PCBs may affect levels of P_4, in polar bear females. There is a clear need to further assess the hormone balance and population health of polar bears at Svalbard.