Our Stolen Futurea book by Theo Colborn, Dianne Dumanoski, and John Peterson Myers
 
 

 

 

New York Times
19 November 2002

Atrazine-hermaphroditic frog study by Hayes

Studies Conflict on Common Herbicide's Effects on Frogs
By CAROL KAESUK YOON

Despite the release of a flurry of new results in what is becoming an increasingly intense debate, scientists still have not reached a consensus as to whether the nation's most commonly used herbicide is harming amphibians in the wild.

The new studies raise questions about whether atrazine, used primarily for killing weeds in cornfields, is acting as an endocrine disrupter in amphibians, interfering with normal hormonal functions, and causing males to become hermaphrodites, producing eggs in their testes. Some 60 million to 70 million pounds of atrazine are applied each year in the United States, and it has been found in rivers, ponds, snowmelt and rainwater.

Scientists have taken a particular interest in the new studies because such a widespread endocrine disrupter could help explain worldwide declines of amphibians.

The studies could also affect continued use of atrazine. The Environmental Protection Agency is reviewing the herbicide's environmental risks as part of the periodic reregistration process required for continued sale of such chemicals.

Much of the newest research was presented yesterday at the Society of Environmental Toxicology and Chemistry in Salt Lake City.

The controversy began in April when Dr. Tyrone Hayes, an endocrinologist at the University of California at Berkeley, and colleagues published results in The Proceedings of the National Academy of Sciences indicating that very low concentrations of atrazine, similar to those seen in the wild, could turn males of the African clawed frog into hermaphrodites in the laboratory.

Then last month in Nature, Dr. Hayes and colleagues published studies showing that males of the leopard frog, a native species, could also be feminized by exposure to low levels of atrazine in the laboratory. More worrisome, the researchers found that in the seven field sites from Utah to Iowa where they could detect atrazine, they also found hermaphroditic frogs. At the one site without detectable atrazine, there were no hermaphrodites.

Two industry-sponsored studies, carried out by a team that has been critical of Dr. Hayes's work, have failed to replicate the findings with the clawed frog. The work was paid for by Syngenta, a maker of atrazine. Yesterday the team also reported that it had examined wild-caught males of the clawed frog where it is native in Africa and where atrazine is widely used and found no hermaphrodites.

"Validated information should be replicable," said Dr. Ronald Kendall, an environmental toxicologist at Texas Tech University and a leader of the industry-sponsored team.

Dr. Hayes said he was surprised by the high levels of hermaphroditism caused by sometimes minute levels of atrazine, with sometimes as many as one-third of the males affected. The effects were less severe at higher levels of the herbicide. But while that might seem counterintuitive, Dr. Hayes said it was typical for chemicals affecting hormones to have highly different, even opposite effects at increased levels.

Dr. Kendall said his team's work had been wrongly impugned as biased because of its industry financing, and he pointed out that Dr. Hayes also formerly received Syngenta financing. Dr. Hayes said his original research showing that atrazine could create hermaphroditic frogs was sponsored by Syngenta, which never published the work. The April publication in which he replicated that research was sponsored by the National Science Foundation; the Nature study was paid for by the W. Alton Jones Foundation, which finances environmental work, and the conservation group WWF.

[Editor's note: what Kendall fails to acknowledge here is that Syngenta/EcoRisk discouraged Hayes from taking his results public once it reached the point that implications for atrazine were clear. This was a time when EPA was in the midst of a large scale review of atrazine, and results showing such extraordinary biological sensitivity to the compound would have been very damaging.

Meeting resistance from Syngenta/EcoRisk, Hayes disassociated from them, obtained independent funding, replicated the work, submitted it to peer-review and then published it in Proceedings of the National Academy of Sciences. Kendall and his team, in contrast, continue to work with Syngenta defending atrazine and have tried repeatedly to discredit Hayes, largely via "science through press release," referring to their work via statements to the press but not allowing independent scientists to analyze it.]

It remains unclear why the studies conflict.

Dr. Hayes, when interviewed, had seen only one of the Kendall team's unpublished studies. Based on the methods, Dr. Hayes said he was not surprised they had not replicated his results. He said that the researchers had raised the frogs under unhealthy conditions and that they did not properly control levels of atrazine in the frogs' water.

[Editor's note: an extraordinary percentage of the Syngenta team's animals failed to metamorphose and those that did were tiny compared to normal animals, apparently having starved. The statistical analysis of their work mysteriously changed between versions, moreover, in ways that decreased the significance of the results. The attempt to use these flawed lab experiment as legitimate science should be regarded as a professional embarrassment to the individuals whose names appear on the paper. Those names, at least in the version submitted to the US EPA docket, are: James A. Carr, Angie Gentles, Ernest E. Smith, Wanda L. Goleman, Lina J. Urquidi, Kerry Thuett, Ronald J. Kendall, John P. Giesy, Tim S. Gross , Keith R. Solomon , and GlenVan Der Kraak].

"Even if their animals were healthy, you can't compare them to our study," he said.

But Dr. Jim Carr, comparative endocrinologist at Texas Tech and a member of Dr. Kendall's team, said that in another study team members had mimicked Dr. Hayes's experimental conditions more closely but still did not produce his results. [This study has not become available for independent analysis; this is most likely more science via press release.] Dr. Carr and colleagues have also criticized Dr. Hayes's omission of certain experiments considered standard.

"There are not a lot of details published in the Hayes work," said Dr. Carr. "So it's hard to compare." [EcoRisk/Syngenta approved Hayes' original laboratory protocols and reviewed the basic results extensively. This is a disingenuous claim.]

 
     
     

 

 

 

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