Common weedkiller turns male frogs into females
By Maggie Fox, Health and Science Editor
WASHINGTON
Wed Mar 3, 2010 3:36pm EST WASHINGTON (Reuters) – Atrazine, one of the most commonly used and controversial weedkillers, can turn male frogs into females, researchers reported on Monday. The experiment is the first to show such complete effects of atrazine, which had been known to disrupt hormones and which is one of the chief suspects in the decline of amphibians such as frogs around the world. “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. The chemical had been shown to disrupt development and make frogs develop both male and female features — termed hermaphroditism. This study of 40 male frogs shows the process can go even further, Hayes said. “Before, we knew we got fewer males than we should have, and we got hermaphrodites. Now, we have clearly shown that many of these animals are sex-reversed males,” Hayes said in a statement. “Atrazine has caused a hormonal imbalance that has made them develop into the wrong sex, in terms of their genetic constitution.” … “Atrazine can be transported more than 1,000 km (621 miles) from the point of application via rainfall and, as a result, contaminates otherwise pristine habitats, even in remote areas where it is not used,” they added, citing other researchers. “In fact, more than a half million pounds (227 tonnes) of atrazine are precipitated in rainfall each year in the United States.” … “Regardless of the mechanism, the impacts of atrazine on amphibians and on wildlife in general are potentially devastating,” they wrote. “The negative impacts on wild amphibians is especially concerning given that the dose examined here (2.5 ppb) is in the range that animals experience year-round in areas where atrazine is used as well within levels found in rainfall, in which levels can exceed 100 ppb in the Midwestern United States,” they added. …
