PCBs and organochlorines in tissues of silverside (Odontesthes bonariensis) from a coastal lagoon in Argentina

A freshwater fish species, silverside (Odontesthes bonariensis) from Mar Ch iquita coastal lagoon, Argentina, was analyzed for concentrations of severa l organochlorine pesticides (OCs) and polychlorinated biphenyls (PCBs) in l iver, gonads, mesenteric fat and muscle, and the contents of the digestive tract over several stages of sexual maturation. PCBs and OCs were detected at ng/g concentrations (wet weight) in pooled samples, with levels generall y in the order of fat > liver > gonad > muscle, reflecting the differences in tissue lipid content. Lipid-normalized concentrations of the analytes we re relatively consistent among tissues, except for significantly higher con centrations of PCBs (e.g., 447.7 ng/g lipid wt) in the ovaries of female si lverside. DDT and its metabolites, gamma-HCH, and several insecticides from the cyclodiene class, including endosulfan and endosulfan sulfate, were th e predominant OCs in fish tissues and the contents of the digestive tract, reflecting recent and past pesticide use in this region. The ratio of OCs t o PCBs in all tissues was. >1; consistent with contamination of the region with OC pesticides. However, PCBs were dominated by penta- and hexachlorobi phenyls, which is consistent with direct (i.e., nonatmospheric) inputs. Bio magnification of penta- and hexachlorobiphenyl PCB congeners was noted in f ish tissues relative to the contents of the digestive tract. Total OC and P CB concentrations in the ovaries and muscle of silverside were below concen trations associated with reproductive impairment in fish or the limits for human consumption, respectively.