The weed killer atrazine, widely used on Florida lawns and golf courses, interferes with the normal growth and development of amphibians and freshwater fish, says an analysis by researchers at the University of South Florida.
USF assistant professor Jason Rorh and postdoctoral fellow Krista McCoy, analyzed more than 100 studies of atrazine, an herbicide banned in Europe in 2004 but still used in the United States and 80 other countries.
The studies showed consistent trends, Rohr said. "Perhaps the most striking were the highly consistent reductions in animal growth and changes in animal behavior associated with atrazine," Rohr said.
In a paper published last week in the peer-reviewed journal Environmental Health Perspectives, Rohr and McCoy wrote that atrazine didn't kill fish or amphibians but had significant "indirect and sub-lethal effects."
In study after study, they found evidence that the weed killer:
• Reduced the size of amphibians at or near metamorphosis.
• Impaired the ability of fish to smell and the ability of fish and amphibians to evade predators.
• Impaired the amphibians' ability to fight infection.
• Altered the reproductive development of male frogs.
Rohr said that for years, researchers have been looking at how atrazine affects the endocrine system of frogs, but he was surprised at the number of studies that showed other effects.
"The thing that was most alarming were the effects on disease risk and growth," he said.
There is more to learn about atrazine, Rohr and McCoy wrote in their paper, but the research shows that the herbicide's effects should be weighed against its benefits and the costs of using alternatives.
Atrazine works by inhibiting photosynthesis in weeds after being absorbed through the roots. It is applied by ground and aerial spraying.
A major manufacturer of atrazine, Switzerland-based Syngenta, celebrated the herbicide's 50th anniversary last month, saying is was one of the most valuable crop protection products ever developed.
"Well over half the corn acres, about two-thirds of sorghum acres and up to 90 percent of sugar cane acres in the United States use atrazine to control weeds," said a company news release.
The U.S. Environmental Protection Agency monitors studies on atrazine, some involving the risk atrazine poses to life in stream systems. A recent EPA review concluded atrazine does not inhibit the male reproductive system in amphibians.
Atrazine is an ingredient in products that have been marketed under the brand names Marksman, Coyote, Atrazina, Atrazol and Vectal.
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