by Rachel Kaufman
Published in National Geographic News
2010-03-01

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The so-called pregnant man has company: One of the most common weed killers in the United States can make male frogs lay eggs, a new study says.

Atrazine, widely used to kill pests on U.S. croplands, is an endocrine disruptor—a substance that interferes with animals’ reproductive systems.

Previous research has shown that atrazine can give male amphibians female characteristics: For instance, male frogs exposed to atrazine have lower testosterone levels, produce less sperm, and even change their mating habits by choosing males over females.

Now, researchers have discovered that the chemical transforms male frogs into fully functioning females—and that the substance may be contributing to a worldwide decline in amphibians.

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