Fighting Attacks on Inconvenient Science—and Scientists

The atrazine wars offer a cautionary tale for scientists whose work triggers blowback by regulated industries, and lessons for protecting scientific integrity.

Tyrone Hayes, an endocrinologist at the University of California, Berkeley, speaks at King University. In 2002, Hayes reported that atrazine, manufactured by Swiss agrochemical giant Syngenta, turned male frogs into hermaphrodites. Credit: Earl Neikirk
Tyrone Hayes, an endocrinologist at the University of California, Berkeley, speaks at King University. In 2002, Hayes reported that atrazine, manufactured by Swiss agrochemical giant Syngenta, turned male frogs into hermaphrodites. Credit: Earl Neikirk

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Any scientist whose research might conceivably threaten the bottom line of powerful corporate interests risks facing an orchestrated campaign to destroy their reputation. 

That’s the message of a commentary, published May 17 in the journal Environmental Toxicology and Chemistry, that spins a cautionary tale about the fragility of scientific integrity by drawing on the disturbing history of a popular weed killer.

The piece focuses on atrazine, explained author Jason Rohr, chair of the Department of Biological Sciences at the University of Notre Dame, because it’s “one of the most commonly used, well studied, and controversial pesticides on the planet.”

The story, filled with intrigue, deception and greed, has all the trappings of a Hollywood movie. It even includes a cast of characters who drew on the same tactics the tobacco and fossil fuel industries deployed against their biggest critics. 


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At its center is Tyrone Hayes, an endocrinologist at the University of California, Berkeley. In 2002, Hayes reported that atrazine, manufactured by Swiss agrochemical giant Syngenta, turned male frogs into hermaphrodites and shrank the larynxes that produce their throaty mating calls. Even more troubling, the chemical caused these effects at doses far below those the Environmental Protection Agency considered safe for drinking water.

Rohr draws on several high-profile stories detailing Hayes’ discoveries and how the industry responded with a multimillion-dollar campaign to discredit him and defend its product.

U.S. farmers applied about 60 million pounds of atrazine to crops in 2019, primarily corn, sorghum and sugarcane in the Midwest. In California, farmers sprayed more than 17,000 pounds of atrazine in 2018, according to the most recent data available, mostly in the Imperial Valley in the southern part of the state on corn and grasses used for hay.

Hayes first discovered atrazine’s gender-bending effects while studying the chemical for its former manufacturer, Novartis (which merged with another company to form Syngenta in 2000). 

Hayes told me he’d naively assumed the company would want to know what he’d found. “Boy they’re going to be glad I figured this out,” he recalled thinking. “Who wants to be selling a chemical that does this?”

Discovering atrazine’s feminizing effects surprised him. He wanted to redo the experiment with a different population of frogs to see if he got the same results.

The company agreed, he said. “But their approach was to delay and spread out the funding.” 

Hayes got that message from another panel member named John Giesy, he said. “He was saying it’s to everybody’s benefit for me to go slow, that I would get paid more for a longer period of time.” 

That’s what Giesy told Hayes he did with PFAS, perfluorinated compounds used to make Scotchgard stain resistant, Hayes said. Documents released through litigation against PFAS manufacturer 3M show Giesy’s role in helping the company hide incriminating science. That lawsuit was settled for $850 million.

Giesy used the Scotchgard example to illustrate what should happen with atrazine, Hayes said. “He said he got paid for a really long time and the company was able to tell the EPA, ‘We’re paying lots of money to have this studied,’ so the EPA was satisfied.”

Plus, the company would have time to develop an alternative compound, get a jump on the competition and phase out the problematic chemical voluntarily. That was supposed to be how “everybody wins,” Hayes said.

Giesy, now Canada Research Chair in Environmental Toxicology at the University of Saskatchewan, did not respond to multiple requests for comment.

Hayes also told an EPA scientist about his findings, but was informed that the agency didn’t consider eggs in frog testicles an “adverse effect.” Hayes was stunned, then disillusioned when he learned that the agency was weighing such effects against the costs of losing a chemical like atrazine. 

“I grew up thinking these are the people that protect the wildlife and the environment and protect the water and stop rivers from being on fire,” he said. “So to have this agency that I idolized say, ‘We need to listen to what the company has to say, because this is an important economic financial product,’ was like learning that firefighters set fires.”

As early as 1995, the EPA knew that atrazine posed health risks, including potentially causing cancer as a result of a lifetime of exposure at levels above those set for drinking water.

Yet in October 2003, a year after Hayes’ papers showed that atrazine changes the sex of frogs, the EPA renewed its registration, even though the agency’s own advisory panel found major flaws in Syngenta’s favorable studies. The same month, the European Union banned the chemical due to risks of widespread water contamination. Just last year, the EPA approved atrazine again, four years after concluding that it poses risks to amphibians as well as a broad range of other species. In 2018, agency scientists found that combined exposures to the chemical from food, drinking water and residential uses could endanger children’s development.

“If you look at the history of the EPA on atrazine,” Rohr told me, “you’ll get whiplash.”

EPA scientists are not at liberty to speak about the recent approval, said EPA Press Secretary Nick Conger, citing litigation contesting the decision. He also said, in an email statement, that the agency is determining its next steps in the atrazine registration review process in accordance with President Biden’s directives to reexamine decisions made during the last administration.

Hayes managed to repeat the work without Syngenta’s funding, thanks to students who worked for free or stipends. “[Syngenta] wanted to offer me money retroactively to get me to sign a confidentiality agreement,” Hayes said. “I said no.”

That’s when the trouble started. 

Hired Guns

Rohr revisited the saga now in a scientific journal—notably in one published by the Society of Environmental Toxicology and Chemistry (SETAC), which has a large chemical industry constituency—partly, he said, because he felt the issue “was worth bringing to people’s attention.”

For Rohr, the story serves as a warning about the many ways science can be exploited to manufacture uncertainty and delay regulatory decisions, to the detriment of scientific integrity and public and environmental health.

Plus, Rohr said, “I got fed up with the attacks on science.”

The sordid details of Syngenta’s campaign came to light in 2013, after a nonprofit journalism group filed a Freedom of Information Act request to unseal documents produced during a class-action lawsuit against Syngenta for atrazine-contaminated drinking water in six states.

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The documents show that the company sought to discredit Hayes and exploit his “faults/problems.” It paid scientists who cast doubt on his research—though Hayes isn’t sure if the experiments failed by design or incompetence—and enlisted crisis communication specialists who considered buying “Tyrone Hayes” as an Internet search term to redirect results to Syngenta material. Hayes said they even threatened his family to the point where he went to the police, who provided him with security on several occasions.

“They couldn’t find a big enough problem in my work to get what they wanted, so they went after me personally,” Hayes said.

Pennsylvania State University climate scientist Michael Mann has seen it all before.

“The attacks on Tyrone Hayes fit into a broader pattern where industry hired guns are paid to engage in dishonest smear campaigns against scientists whose findings prove inconvenient to powerful special interests,” said Mann, who has long been a target of the fossil fuel industry.

Mann pointed to veteran climate denier Steven Milloy, who called Hayes a “Berserkeley atrazine hater” and accused him of lying about his science. 

Milloy used the same tactic on Mann that Syngenta reportedly considered using on Hayes. Milloy bought a Google ad that accused Mann of hiding temperature declines, resurrecting lies conjured from hacked emails in the so-called ClimateGate scandal that allegedly showed that climate scientists manipulated data to exaggerate the threat of climate change. The ad, Mann recounts in his book The Hockey Stick and the Climate Wars, popped up whenever someone searched for Mann’s name, “climate change” or related keywords. 

Naomi Oreskes, a Harvard University historian who studies industry disinformation campaigns, said she knows people who proactively bought Internet domain names in areas they work to prevent others from “making mischief” with their name or topics.

“For a long time, if one googled ‘climate change,’ the top hits were to denial sites,” Oreskes said.

Syngenta did not respond to a request for comment.

Resisting Influence Campaigns

SETAC, which published Rohr’s commentary, hosts scientific meetings that Rohr described as stressful. “Syngenta would always have as many people there as possible and you’d be attacked, regardless of what sort of data you presented,” he said. 

Companies have a right to defend their products, he said. But such aggressive tactics  make it challenging to attract young scientists to the field. “No one wants to deal with that.”

What’s most concerning about the tactics, said Stephan Lewandowsky, chair in cognitive psychology at the University of Bristol, “is that not all universities and not all academics are willing or able to resist those attacks and attempts to bend science to an industry’s interest.”

But publishing stories like the atrazine saga, Lewandowsky said, should help well-intentioned academics and universities learn how to spot industry-sponsored “influence operations.”

Rohr said he’s “very grateful” to Hayes for speaking out, and for taking a lot of the flak.

Hayes, for his part, is grateful that his story—now being developed into a movie—is  before an audience that includes Novartis, Syngenta and “all of the players” involved in the campaign to defend atrazine. 

Hayes takes issue with some things in the article, however. For example, he said he never served as an expert witness in the class-action lawsuit or any other case. “Everybody wants to accuse me of being a high-paid expert witness,” said Hayes, who also denies receiving payments, other than research grants, from nonprofit organizations. “Never happened.”

Hayes is troubled that, even after all these years, environmental and public health are still at risk from atrazine, which he calls the “poster child for things that we need to do differently.”

Atrazine can travel hundreds of miles through the air, Hayes said. Many studies have shown that pesticides used in California’s Central Valley move into the Sierras, where endangered and threatened amphibians like the red-legged frog live, and contaminate wildlife. 

But he said he worries most about agricultural workers. Research has linked atrazine to birth defects and cancer, prompting Syngenta to sponsor reviews disputing both findings

When Hayes gives talks to audiences outside of California, he points out that the state produces a large share of the nation’s food, which helps make California the fifth largest economy in the world. “And the people who make us the fifth largest economy in the world are targets of chemicals that we know have adverse impacts on their health.”

For Rohr, a major lesson of the atrazine story is that regulators should no longer rely on the companies that make a product to determine whether it’s safe.

“If you want to manufacture uncertainty, then it doesn’t really matter if the EPA says that it’s dangerous in one year and then says that it’s not dangerous in another year,” Rohr said.  “Because really the goal is just to make sure that you’re delaying any regulations.”

“The benefits of bending science far exceed the costs in those cases,” he said. “And it puts all of us at risk.”

An earlier version of this article incorrectly characterized the financing Tyrone Hayes, an endocrinologist at the University of California, Berkeley, has received from nonprofit organizations. He has received research grants, but no other payments.