Effects of oral exposure to polychlorinated biphenyls (PCBs) on the development and metamorphosis of two amphibian species (Xenopus laevis and Rana temporaria)

This study examined the effects of polychlorinated biphenyls (PCBs) on deve lopment of families of amphibians using the African clawed frog (Xenopus la evis) and the European common frog (Rana temporaria). Amphibians were orall y exposed to the technical PCB-mixture Clophen A50 or to the non-ortho-3,3' ,4,4',5-CB congener (PCB 126) either for a 10-day period or until metamorph osis. Occurrence and rate of malformations, mortality, period until metamor phosis and thyroid hormone levels were measured. Mortality increased in a d ose-dependent manner, as did the rates of malformation. Time until metamorp hic transformation was prolonged and the weight of froglets was increased. Although not statistically significant, thyroid hormone levels were also lo wered. PHAHs such as PCBs may affect important aspects of amphibian fitness and may influence amphibian reproductive success. (C) 2000 Elsevier Scienc e B.V. All rights reserved.