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E. Exposure to Pesticide Interferes with Frog Sexual Development

Narrator: This is Science Today. A recent study has found that frogs exposed to a common pesticide called atrazine have problems with the development of their sexual characteristics. Biologist Tyrone Hayes of the University of California, Berkeley says some of the testosterone was converted to estrogen.

Hayes: The conversion of testosterone to estrogen results in a drop in the masculinizing hormone, so that animals don't develop some of their masculine features if they're male. But in addition, they're also feminized. The production of estrogen by the male frogs causes development of female characters that don't normally appear in males.

Narrator: Although the effects of these changes on frog fertility are not yet known, Hayes says his results could have implications for human health.

Hayes: The genes that control sex and gonadal differentiation in humans, those same genes are present in amphibians. Some of the sequences are exactly the same. Male frogs croak and females don't. In humans, males have deeper voices than females for the same reasons.

Narrator: For Science Today, I'm Larissa Branin.