ECOTOXICOLOGICAL STUDIES IN AMPHIBIAN POPULATIONS OF SOUTHERN ONTARIO

In order to evaluate the relative exposure and stress of environmental contaminants on amphibian populations of Southern Ontario, two specie s of frogs, Rana pipiens and Rana clamitans, were collected from nine sites and analyzed for polychlorinated biphenyls (PCBs) and pesticides . Sediment samples were also collected and analyzed for PCBs, pesticid es, and polycyclic aromatic hydrocarbons (PAHs). Biota-sediment accumu lation factors (BSAFs) were calculated for PCBs and pesticides at all sites for both species of frogs. BSAFs ranged from 33.28 +/- 16.16 to 1.06 +/- 0.0 for leopard frogs and from 23.02 +/- 7.89 to 0.42 +/- 0.0 for. green frogs. Sediment extracts were further tested for cytotoxic ity and genotoxicity on a leopard frog embryo cell line. The Neutral R ed Uptake bioassay was used to measure cytotoxicity and a DNA break bi oassay was used to test genotoxicity. Cytotoxicity was evident in four of the nine sites, Cornwall, Brighten, Ancaster, and Ojibway, at 200 g sediment equivalents per liter of culture medium. Genotoxicity, expr essed as F-values, ranged from 0.921 +/- 0.052 to 0.975 +/- 0.004, ind icating that sediment extracts were not causing significant genotoxic stress.