From the AmphibiaWeb Site:
Atrazine is the most common pesticide contaminant in ground, surface, and drinking water. It also is a potent endocrine disruptor at very low concentrations across vertebrate taxa. In a new PNAS paper, Hayes et al. (2010) showed that atrazine exposure during larval development at levels below the EPA drinking water standard can profoundly affect male Xenopus laevis (African Clawed Frog) sexual function and morphology. In the most severe cases, male frogs were completely feminized morphologically and behaviorally, producing eggs and mating with other males.
Amphibian declines may be due not only to disease and habitat loss, but to failure to reproduce (see the recent review by Hayes et al. (2010) in the Journal of Experimental Biology).