Agribusiness groups are accusing U.S. EPA of putting politics ahead of science in its decision to reassess a common herbicide, atrazine.

Tim Pastoor, a scientist with atrazine manufacturer Syngenta AG, said yesterday that EPA has failed to follow its own procedures for evaluating new research, given the agency's 2006 re-registering of atrazine.

"EPA's reviews have been thorough and transparent, and the studies they have used have been -- in sheer volume and depth -- unprecedented for any other pesticide," Pastoor said. "Atrazine is probably one of the best-studied molecules on the planet."

EPA officials told a scientific advisory panel yesterday they want to focus on the pesticide's potential for causing cancer, as well as its potential effects on endocrine systems. The agency wants to assess research on farm workers and pesticide applicators.

Steven Bradbury, deputy director of the Office of Pesticide Programs, said EPA is not trying to prejudge atrazine but instead wants to make sure it stays on top of the science.

"We don't make regulatory decisions without understanding the science," Bradbury said. "The first step is making sure we're current with the science and understand the science."

But Ray McAllister, senior director of regulatory policy at CropLife America, said the move appears to be politically motivated. Of particular concern to CropLife, Syngenta and others is that EPA has not presented new scientific evidence suggesting such a review is necessary. Several groups said EPA appears to be bowing to environmental concerns that are not rooted in science.

"I think this is being driven by folks that are anti-farming, anti-agriculture," said Gary Marshall, with the Missouri Corn Growers Association.

Environmentalists applauded EPA's decision. Jennifer Sass, a senior scientist with the Natural Resources Defense Council, said EPA is right to review the science surrounding atrazine because several recent studies suggested the herbicide affects growth rates and behavior in frogs. Sass also pointed to water monitoring tests showing some towns have had spiking atrazine concentrations in drinking water.

"The peaks are a real concern because of their impact on wildlife," Sass said.

But Pastoor said the studies that Sass referenced do not meet scientific standards, and EPA should not be asking its science advisers to weigh in until the agency determines whether the studies merit further review.