Abstract: The amphibian metamorphosis assay (AMA) was used to detect thyroid disrupting effects of perfluorooctane sulfonate (PFOS). Xenopus laevis tadpoles at stage 51 were exposed to 10, 50 and 250 μg·L-1 PFOS. The growth, metamorphosis and thyroid histology were observed. After 7 days of exposure, the hind limb lengths were decreased by 11%～18%, and 1 or 2 developmental stages were delayed in treatment groups compared with the control. After 19 days of exposure, the body weights were increased by 10%～20%, the body lengths were increased by 4%～6%, and the hind limb lengths were decreased by 12%～13% in treatment groups. PFOS decreased the number of thyroid follicles, in which cell hyperplasia, colloid depletion and vacuolation were observed. These results suggested that PFOS inhibited the development and increased the growth of X laevis. According to AMA, our results indicated that PFOS was an antithyroid hormone disrupting chemical.

Key words: Xenopus laevis, perfluorooctane sulfonate (PFOS), amphibian metamorphosis assay (AMA), thyroid disrupting chemicals (TDCs), Xenopus laevis, perfluorooctane sulfonate (PFOS), amphibian metamorphosis assay (AMA)