“Atrazine-exposed males were both demasculinized (chemically castrated) and completely feminized as adults,” Tyrone Hayes of the University of California Berkeley and colleagues wrote in the Proceedings of the National Academy of Sciences.
Previously the chemical had been shown to disrupt development and create hermaphroditism in frogs, whereby they develop both male and female features. This latest study of 40 male frogs shows the process can go even further, Hayes said. “Atrazine has caused a hormonal imbalance that has made them develop into the wrong sex, in terms of their genetic constitution.”
Whether the effects translate to humans is far from clear. Frogs have thin skin that can absorb chemicals easily and they literally bathe in the polluted water.
The European Union banned atrazine in 2004. The finding may add pressure to the United States to more closely regulate the chemical, used widely in agriculture.
“Approximately 80 million pounds (36,000 tonnes) are applied annually in the United States alone, and atrazine is the most common pesticide contaminant of ground and surface water,” the researchers wrote.
“In fact, more than a half million pounds (220 tonnes) of atrazine are precipitated in rainfall each year in the United States.”
The U.S. Environmental Protection Agency said in October it was reviewing the health impacts of atrazine.