STORRS, Sara I.*; SEMLITSCH, Raymond D.; University of Missouri: Is hermaphroditism natural in amphibians?: A case of contaminated controls

Is hermaphroditism natural in amphibians? Preliminary histological data from an outdoor mesocosm study suggest that a female biased sex ratio and abnormal gonads in control animals may be the result of contamination. The experiment was initiated to examine the effects of atrazine (0, 3, 30, 100 ppb) on gray treefrogs (Hyla versicolor) in Missouri. Twice during the experiment, water in high density polyethylene cattle watering tanks (with and without animals) and water used to fill the tanks was sampled for an MCF-7 human breast cancer cell bioassay. The results of the assay demonstrate that water in the tanks was very estrogenic and resulted in cell growth equivalent to that of estradiol concentrations as high as 1 x 10^-10M, while that from the hose used to fill the tanks was negative. Water was also sampled from the tanks to examine nominal atrazine concentrations (0, 3, 30, 100 ppb) which correspond to estimated concentrations of 0.10 � 0.07, 3.56 � 0.49, 31.69 � 11.63, and 117.83 � 19.84 ppb (mean � SD). Contamination of outdoor mesocosms may lead to false indications that hermaphroditism is a natural phenomenon in amphibians. Background levels of estrogenic activity in experimental waters should be tested to ensure true controls. These data are important in light of the recent focus on atrazine exposure of amphibians.