PCBs and DDT in the serum of juvenile California sea lions: associations with vitamins A and E and thyroid hormones

Top-trophic predators like California sea lions bioaccumulate high levels of persistent fat-soluble pollutants that may provoke physiological impairments such as endocrine or vitamins A and E disruption. We measured circulating levels of polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane (DDT) in 12 healthy juvenile California sea lions captured on An-tilde o Nuevo Island, California, in 2002. We investigated the relationship between the contamination by PCBs and DDT and the circulating levels of vitamins A and E and thyroid hormones (thyroxine, T4 and triiodothyronine, T3). Serum concentrations of total PCBs (ΣPCBs) and total DDT were 14 ± 9 mg/kg and 28 ± 19 mg/kg lipid weight, respectively. PCB toxic equivalents (ΣPCB TEQs) were 320 ± 170 ng/kg lipid weight. Concentrations of ΣPCBs and ΣPCB TEQs in serum lipids were negatively correlated (p < 0.05) with serum vitamin A and T3, potentially reflecting PCB-related toxicity. A slight but not significant negative correlation (p < 0.1) was observed between serum T4 and the levels of ΣPCBs and ΣPCB TEQs. Conversely, no relationship was evident between the contaminant concentrations and vitamin E (p > 0.1). As juvenile California sea lions are useful sentinels of coastal contamination, the high levels encountered in their serum is cause for concern about the ecosystem health of the area. - Results show high levels of organochlorine contaminants in juvenile California sea lions and a link between vitamin A, thyroid hormones and PCB exposure