Why Are Frogs Growing Multiple Sex Organs?Apr 18, 2002 With such beautiful spring weather, it's hard to imagine anything wrong with our environment. But a new frog study is ringing an important alarm about a popular herbicide.
Deformed frogs were found a few years ago. Now scientists are finding a new problem, reproductive abnormalities in frogs.
"It could have a big affect on the future of reproduction in humans," UW zoology professor Stanley Dodson said.
The new research looks at atrazine, the most popular weedkiller in the country and one still sprayed on 90 percent of Wisconsin corn.
A California scientist found male frogs exposed to even very low levels of atrazine, like those commonly found in our lakes and groundwater, can develop multiple sex organs, or male and female organs.
Dodson likens the study to a canary in a coalmine. Dodson found low levels of atrazine affect the reproduction of water fleas. Atrazine makes the usually female offspring become male. But he said because frogs are similar to humans, the new study is a real wake-up call.
"We're rolling the dice," he said. "It's like a long-term experiment that we're doing."
Those who represent the manufacturers and distributors of atrazine said it should not be banned yet.
"I think it's too early for that," said Betsy Ahner of the Wisconsin Fertilizer and Chemical Association. "I think we need to be sure the study is scientifically valid before we do anything else, but certainly it bears watching."
For years now, Wisconsin has regulated and reduced the use of atrazine.
"They're doing a good job reducing atrazine in the environment but this study really sort of pushes us to sort of look at it further," said Wisconsin Department of Agriculture Water Quality Chief James Venden Brook.
Venden Brook said it might be time to think about an atrazine standard for surface water. Right now Wisconsin has one for groundwater, it is three parts per billion.
The sexual organ changes in frogs followed concentrations as low as one-tenth of a part per billion.