Effects of oral exposure to polychlorinated biphenyls PCBs/ on the development and metamorphosis of two amphibian species Xenopus lae¨is and Rana temporaria/

This study examined the effects of polychlorinated biphenyls PCBs. on development of families of amphibians using the African clawed frog Xenopus lae¨is. and the European common frog Rana temporaria.. Amphibians were orally exposed to the technical PCB-mixture Clophen A50 or to the non-ortho-3,39,4,49,5-CB congener PCB 126. either for a 10-day period or until metamorphosis. Occurrence and rate of malformations, mortality, period until metamorphosis and thyroid hormone levels were measured. Mortality increased in a dose-dependent manner, as did the rates of malformation. Time until metamorphic transformation was prolonged and the weight of froglets was increased. Although not statistically significant, thyroid hormone levels were also lowered. PHAHs such as PCBs may affect important aspects of amphibian fitness and may influence amphibian reproductive success.