Pesticides Linked To Widespread Cases Of Deformed Frogs

The recent finding of abnormal frogs in many different states and Canada spanned a wide range of amphibians and was not limited to species, geography or climate, according to James J. La Clair of The Scripps Research Institute in La Jolla, Calif. In a new report in the April 14 Web edition of Environmental Science & Technology, La Clair and colleague John Bantle offer an explanation for these findings by examining the effects of pesticide degradation in the early amphibian development.

La Clair's group found that S-methoprene, an insect growth regulator that was introduced in the late 1970s to control fleas and mosquitos, posed little risk to the development of amphibians. However, when exposed to sunlight, water and microorganisms, La Clair found that S-methoprene breaks up into other products that dramatically alter embryo development. By adding minute amounts of these degradation products to developing embryos of the African clawed frog, Xenospus laevis, the Scripps group found that the embryo developed into a juvenile with deformations similar to those found in nature.

La Clair emphasizes that the current procedure of assessing the risk posed by pesticides by examining only the host pesticide must be changed to include the relationship between amphibian development and the degradation products that form under natural conditions.

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