"... I regret that the EPA science staff in the office of Pesticide Program's EFED (Environmental Fate
and Effects Division) could not properly account for the sample sizes and study design reportedly used by the Berkeley researchers. As a result, we were unable to complete any independent analysis to support the study's conclusions."
"...no reliable determination of cause-effect or concentration-response relationship could be established between atrazine and reported effects in amphibians."
"EPA presented its review to a FIFRA (Federal Insecticide, Fungicide Rodenticide Act) SAP (Scientific Advisory Panel) and concluded that it was reasonable to reject the hypothesis formulated in 2003 that atrazine exposure can affect gonadal development. The Agency also determined that there was no compelling reason to pursue additional testing with regard to the potential effects of atrazine on amphibian gonadal development."
"EPA has taken an especially close look at the research conducted by Dr. Tyrone Hayes which reports that atrazine adversely affects sexual development in frogs, causing a mixture of sex organs in a single animal. EPA has concluded that the existing data are insufficient to demonstrate that atrazine causes such effects. The Agency's conclusions are supported by the independent, expert peer review of the SAP (Science Advisory Panel)."
In their native habitats, African clawed frogs do not appear to be suffering from the herbicide. "Atrazine has been used widely in South Africa for the past 45 years, and our studies showed that Xenopus are doing equally fine in agricultural and nonagricultural areas," says zoologist Louis du Preez of North-West University in South Africa. "If atrazine had these adverse effects on Xenopus in the wild, surely we would have picked it up by now."