|NEWS OF THE WEEK
Volume 80, Number 16
CENEAR 80 16 p. 9
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Atrazine, the most commonly used weed killer in the world, disrupts the sexual development of male frogs.
"Atrazine-exposed males have ovaries in their testes and much smaller larynges [voice boxes]," Hayes says. The herbicide also lowers the levels of testosterone in sexually mature male frogs by a factor of 10.
There is virtually no place in the U.S. that is not contaminated with atrazine, Hayes says. It is the second most frequently detected water contaminant and, according to U.S. Geological Survey studies, can be found at levels as high as 21 ppb in groundwater and 42 ppb in surface waters during the growing season in the Midwest. So the chances that amphibians are exposed to atrazine levels of 0.1 or more are extremely high, Hayes explains.
Belgium, France, Germany, Italy, Norway, Sweden, and Switzerland have banned the use of atrazine. These countries have banned all pesticides that tend to occur in drinking water at levels higher than 0.1 ppb, Pastoor says, primarily on the basis of occurrence in water, not health studies.
John P. Giesy, a chemist and ecotoxicologist at Michigan State University, and his student Katherine K. Coady are also investigating the effects of atrazine on frogs exposed in the wild. Even if atrazine is disrupting sexual development, it may not be harming the survival of the species, Giesy says.
Hayes believes, however, that atrazine could be one factor contributing to the worldwide decline of amphibians. As C&EN went to press, EPA was scheduled to release its revised risk assessment for atrazine.
Chemical & Engineering News