Magazine article Science News

Feminized Frogs: Herbicide Disrupts Sexual Growth. (This Week)

Magazine article Science News

Feminized Frogs: Herbicide Disrupts Sexual Growth. (This Week)

Article excerpt

At common environmental concentrations, the popular weed killer atrazine strips male frogs of a key hormone and turns some of them into hermaphrodites, according to new research. The finding raises concerns that the chemical may be contributing to global amphibian declines.

In use for about 4 decades and currently employed in 80 countries atrazine is the most common herbicide in the United States. It's found in virtually all the nation's waterways and is especially prevalent around cornfields in the Midwest. It has also been identified in tests of preschoolers' drinking water (SN: 11/3/01, p. 285). "There seems to be no atrazine-free environment," says Tyrone B. Hayes of the University of California, Berkeley.

Past research has found no evidence that typical environmental concentrations of atrazine cause premature death or abnormal growth in amphibians. The new research, which Hayes and his colleagues report in the April 16 Proceedings of the National Academy of Sciences, similarly finds that mortality and overall growth of the common lab frog Xenopus laevis are unaffected by atrazine.

However, the researchers report, the herbicide has significant effects on frogs' sexual development. These turn up at concentrations substantially lower than the 3 parts per billion (ppb) that the Environmental Protection Agency permits in drinking water.

To investigate atrazine's effects on sexual development, the researchers exposed tadpoles to concentrations ranging from 0. …

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