Popular herbicide may gender bend wild frogs

Toxicologists concerned that atrazine can feminize male frogs

Source: Jay Withgott
New Scientist November 2 2002 p13

Toxicologists are concerned that atrazine, commonly used on corn crops in the US, can feminize male frogs. Forty per cent of herbicides used in the US are atrazine-based, and the Enviromental Protection Agency (EPA) could restrict their usage.

A team from University of California, Berkley, headed by Tyrone Hayes, an endocrinologist, first studied Xenopus laevis, a species from Africa, used in laboratories, and then went on to look at native wild frogs in the US. Both the African frogs, and Tana pipiens, or northern leopard frogs, develop ovaries and their voice boxes shrink. His initial research found that even a dose of one thirtieth the EPA standard for safe drinking water could have this effect. Low doses could affect the frogs more severely than higher ones, which may be because they appear similar to hormones at low levels. The research has been reported in Nature, vol 419 p895. Syngenta, which makes atrazine, has funded other research, and these researchers argue that their research shows that, while atrazine does feminize frogs, it only does so at high doses. Atrazine has been banned in many countries in Europe.