Popular Pesticide Faulted for Frogs' Sexual Abnormalities
By JENNIFER 8. LEE

WASHINGTON, June 18 — Scientists from the Environmental Protection Agency say there is "sufficient evidence" to conclude that the country's most widely used pesticide, atrazine, causes sexual abnormality in frogs.

They are recommending that the agency conduct more research to understand atrazine's mechanisms and its broader impact on frog populations.

The scientists noted that there had been six studies involving three species of frogs that show a variety of defects, including frogs with both multiple testes and multiple ovaries, when exposed to the chemical. The scientists cautioned that the results from studies of atrazine had not been consistent and that it was not clear at what levels of exposure those effects occurred or how different frog species were affected.

"Over several studies and environmental conditions and species, atrazine exposure did appear to be having some impact on gonadal effects," Tom Steeger, a scientist with the environmental agency's pesticide office, said on Tuesday in a presentation to an independent scientific panel convened here to assess atrazine's impact on amphibians.

Scientists hired by Syngenta, a major manufacturer of atrazine, said they drew different conclusions from available research.

"We see no correlation in the adverse gonadal effects and the introduction and use of atrazine," Glen Van der Kraak, a professor at the University of Guelph in Winnipeg, Manitoba, said in a presentation to the panel.

But E.P.A. scientists said many of the industry-sponsored studies had a variety of problems, including testing conditions that led to high mortality in their frogs. The four-day hearing by the panel, which ends on Friday, is an extension of the E.P.A.'s nine-year review of whether atrazine poses unacceptable risks to the environment and to public health. Later this year, the panel will make recommendations to the agency on how to proceed.

Atrazine and its byproducts are widely found at low levels in United States waters, especially after the planting season, when rains wash the chemical out of fields. It is popular with farmers because it is effective and relatively cheap. Atrazine has been banned in seven European countries.

Some laboratory studies have linked atrazine to cancer in rats, and some epidemiological studies show a correlation between exposure and cancer in humans.

The E.P.A. review had been moving toward renewing the agency's approval to use atrazine. But last year, a scientist at the University of California published two papers suggesting that low levels of exposure to atrazine, as low as one part per 10 billion in the water, could cause tadpoles to develop into frogs with both male and female sexual organs.

The studies, led by Tyrone B. Hayes, were published in April 2002 in the Proceedings of the National Academy of Science and in October 2002 in Nature magazine. Dr. Hayes had originally been hired by a consulting concern, Ecorisk, to conduct studies on atrazine on behalf of a company that is now Syngenta. The studies ignited a scientific and political debate, and led the environmental agency to convene the panel to examine atrazine and its effects on amphibians.

Initially, Syngenta said it had been unable to replicate the results of Dr. Hayes's work in company-sponsored studies. But since then, one of the company studies was published in a journal, Environmental Toxicology and Chemistry, and its primary author, Dr. James Carr of Texas Tech University, said the study did result in some hermaphrodite frogs, though at higher exposure levels than in Dr. Hayes's studies.

Dr. Hayes and other Berkeley faculty members present at meetings about his work say that when Dr. Hayes presented his findings to a panel of university scientists formed by Ecorisk, some of the panel members tried to delay him from publicizing his initial findings. Other scientists on the Ecorisk panel say any delay was intended to test the validity of the data.

Dr. Hayes left the panel in protest in November 2000, stating in his resignation letter that otherwise "it will appear to my colleagues that I have been part of a plan to bury important data."

Syngenta has submitted Dr. Hayes's initial work in an interim report to the E.P.A. The company has not submitted a final report on his research to the agency.

The two papers Dr. Hayes and his co-authors published in 2002 were based on research done without industry financing.

Tim Pastoor, who is in charge of global risk assessment for Syngenta, said, "There were absolutely no constraints on any of the panel members on anything they have found."

But the minutes from a January 2001 Ecorisk panel show Tim Gross, University of Florida professor, [ed. note... actually USGS] who is also part of the Ecorisk panel, telling Dr. Hayes that the "results from the contracts are jointly owned" by the company and the scientist. "Therefore, publication is upon mutual consent," Dr. Gross said in a letter submitted at the meeting.

He said Dr. Hayes "should be reminded of this, as well as the confidentiality of these results."

The minutes were submitted to the environmental agency and obtained by the Natural Resources News Service through a Freedom of Information request.

But today, Dr. Hayes spent several hours presenting his research to the panel.

The atrazine discussion is a high-profile inquiry into the relatively new scientific area of endocrine disruptors, chemicals that at minute traces can significantly affect health by interfering with the hormones that regulate biological activity. Several studies from the last decade linked the trace pollutants to declining sperm counts, infertility and various forms of cancer in humans, as well as genital malformation in wildlife.