Meeting Abstract

P3.90  Saturday, Jan. 5  Use of a Tadpole Tail Regression Assay to Evaluate The Endocrine Disrupting Capacity of a Commonly Used Pesticide SOTO-PE�A, J.S.*; SCHWENDIMAN, A.L.; SEARCY, B.T.; PROPPER, C.R,; Northern Arizona University; Northern Arizona University; Northern Arizona University; Northern Arizona University toxicita@yahoo.com

Wide spread use of the common pesticide, endosulfan, has lead to environmental contamination of surface and ground water. Because endosulfan has demonstrated endocrine disrupting effects impacting the thyroid hormone system, exposed individuals and wildlife populations may be at risk for thyroid hormone related health issues. The Environmental Protection Agency (EPA) recommends a dose of 74 ppb in water-containing areas, and 0.1-0.2 ppm on agricultural surfaces. Using a tadpole tail regression assay as a bioassay for thyroid hormone-like responsiveness, we tested the hypothesis that environmentally relevant concentrations of endosulfan impact this thyroid hormone-dependent process. Xenopus laevis tadpole tails were measured and then exposed to 0.05 �g/L, 10 �g/L, 100 �g/L, and/or thyroid hormone (T3: 10 nM) for 72 hours. At this time, tails were again measured and the change in tadpole tail length was determined. We found that endosulfan, even at doses as low as 0.05 ppb mimicked the effect of thyroid hormone in the tadpole tail assay, suggesting that this compound may have direct thyroid hormone like actions. We are currently evaluating changes in gene expression of thyroid hormone sensitive genes, which are involved in thyroid hormone signaling in a wide range of vertebrates.