Monsanto displays its weedkiller Roundup in its headquarters in Saint Louis | Brent Stirton/Getty Images Monsanto attempts takedown of agency linking its weedkiller to cancer Debate focuses on whether scientists failed to consider German studies on the safety of glyphosate.

Monsanto is on the attack.

In its fight to keep its blockbuster weedkiller glyphosate on the European market, the American agrichemical giant has spent the last six months fighting accusations that it suppressed negative findings or even ghostwrote key research about whether the herbicide causes cancer.

Now the company is opening a new front with evidence it says debunks the only appraisal by a major world body to label glyphosate as carcinogenic.

POLITICO analyzed hundreds of previously undisclosed documents from a high-profile court case in San Francisco and conducted interviews with numerous scientific experts to tell the tale of the intense battle between Monsanto and scientists over the controversial finding. Monsanto gave POLITICO exclusive access to the court documents.

The global pesticides powerhouse is questioning the findings of scientists who worked for the World Health Organization's International Agency for Research on Cancer (IARC). In 2015, the agency made glyphosate one of Europe's most toxic political issues when it concluded the weedkiller "is probably carcinogenic to humans."

It was a hammer blow to Missouri-based Monsanto, whose blockbuster product Roundup, a favorite among farmers and gardeners, is based on the herbicide. It also whipped up an intense EU-wide debate over whether farmers should be allowed to continue utilizing a product they have used for more than four decades and that they say is vital to preserve yields of common crops from carrots to barley.

Scientists and contributors to the IARC review say the company’s claims are part of an industry-led witch hunt against the only scientific body to question glyphosate’s safety.

IARC's findings were later dismissed by two EU bodies — the European Chemicals Agency and the European Food Safety Authority — but remain a significant reference point in the debate surrounding the pesticide's health risks.

In Europe at least, the battle over glyphosate appears to be entering the endgame. The EU is soon expected to make a final ruling on whether to reapprove the chemical's license for 10 years, and momentum is building in favor of doing so. German Chancellor Angela Merkel and her agriculture minister, Christian Schmidt, have thrown their weight behind the weedkiller. Failure to continue selling glyphosate in Europe beyond the end of the year would cut into a sizeable chunk of Monsanto's pesticides business, which earns it billions of dollars every year across the globe.

Monsanto wants to seize on the pendulum swing spearheaded by Germany by undermining how IARC reached its original decision. To do so, the company zeroed in on testimony found in a sworn deposition from Charles William Jameson, a world-renowned scientist who specialized in animal studies at IARC. The deposition reveals, Monsanto says, that IARC unfairly disregarded two important pieces of research from Germany that suggested the herbicide was safe.

Scientists and contributors to the IARC review say the company's claims are part of an industry-led witch hunt against the only scientific body to question glyphosate's safety.

Journey to Lyon

Jameson arrived at IARC's offices in Lyon, France, on March 3, 2015, to begin a week of closed-door talks evaluating the carcinogenicity of glyphosate. The now-retired scientist from the National Institute of Environmental Health Sciences in the U.S. was in charge of deciding whether the available scientific evidence in the public domain proved the herbicide could cause cancer in humans.

The decision to evaluate glyphosate's safety was made in 2014 after an international advisory group of senior scientists and government officials recommended dozens of pesticides, including glyphosate, for evaluation.

Little did Jameson know, however, when he sat down alongside the IARC working group's 17 other scientific experts, that he did not possess the full picture, he said in the deposition. Ten days after Jameson arrived, the IARC said glyphosate was "probably carcinogenic to humans."

The undisclosed court documents seen by POLITICO that are now at the heart of a legal case against Monsanto in California raise questions about whether the IARC properly considered two pieces of scientific work from Germany. Lymphoma patients, who say their condition was caused by glyphosate, brought the case after seeing ads for a free evaluation of their illnesses from several U.S. law firms.

The proceedings, which began in 2016, snowballed into a broader investigation into whether glyphosate is harmful. Later this year, Judge Vince Chhabria of the United States District Court for the Northern District of California will issue an unusual verdict on whether decades of scientific evidence support a direct link between glyphosate and cancer. A hearing on the case is scheduled for next week.

Early in the case, Monsanto came out looking worse than ever: Court documents released by the judge implied that company executives attempted to suppress information about the potential dangers of its Roundup herbicide. In at least one case, they seemed to have "ghostwritten" research on glyphosate then hired academics to put their names to a peer-reviewed publication.

Then, in May, Jameson was questioned by lawyers representing Monsanto. Jameson is a paid expert witness on behalf of the lymphoma patients. He told them he hadn't received key data that would have contributed more deeply to IARC's assessment of glyphosate.

Monsanto sensed an opportunity to seize the narrative.

Hidden details?

The first alleged omission raising concerns over IARC's decision concerns data from Germany's Federal Institute for Risk Assessment (BfR). It concluded glyphosate was not carcinogenic in 2015. In a May 3 deposition, Jameson said he neither received nor consulted any data from BfR, although it was sent to IARC on February 3, 2015, a full month before its assessment began in Lyon, France.

“When an organization such as IARC is given authority, with that comes a responsibility … to be objective, transparent, thorough and fair" -- Scott Partridge

The second questionable omission is a peer-reviewed study by the German scientist Helmut Greim drawing on tumor data from 14 carcinogenicity studies on rats. Jameson's deposition, as well as email correspondence between Monsanto and IARC, reveal that Jameson was never sent Greim's study until the very last moment even though IARC had it a month before making its assessment. Greim's work was sponsored by Monsanto.

Presented with evidence by Monsanto's lawyers showing that two of his colleagues at IARC — Kate Guyton, the officer responsible for IARC's monographs section, and Ivan Rusyn, a member of the IARC working group — received the full set of data from Greim's peer-reviewed study on February 3, 2015, but had not sent it to him, Jameson replied while giving sworn testimony in a deposition: "I'll be damned."

Jameson told lawyers he saw the Greim study only a day before the IARC meeting in a subgroup chair meeting, which prepared IARC's assessment. Had IARC been able to analyze the contents of the study properly, he said, it could have altered the agency's final conclusions as he was in charge of the IARC team tasked with analyzing animal tests.

"There was a lot of discussion around the table about if this publication should be even looked at, because it was not received in the time identified in the announcement for submission of data that IARC had for this particular monograph meeting," Jameson said in the deposition. The deadline to submit data to IARC was February 3, 2015.

A spokesperson for IARC denied to POLITICO that data was withheld from Jameson and said that all public data it receives is distributed "via shared electronic resources, to which the entire Working Group has simultaneous access."

Jameson also said that the amount of data received from the Greim study was so "overwhelming" it would not have been possible to do a full review during the meeting in Lyon.

IARC said the Greim study was summarized as part of the overall assessment on glyphosate, though it declined to answer questions about why the raw data used in the study were not fully analyzed, which Monsanto has described as an important omission.

The revelations add to questions about IARC's decision after Reuters revealed in June that Aaron Blair, who chaired IARC's working group on glyphosate, had seen unpublished but acclaimed research finding no evidence of a link between glyphosate and cancer but chose not to include the findings in IARC's review. That research was carried out by the Agricultural Health Study, which is funded by the U.S. government's National Cancer Institute and National Institute of Environmental Health Sciences.

'IARC ... violated responsibilities'

To the experts at Monsanto, the handling of the German evidence is a clear sign IARC made mistakes. Scott Partridge, Monsanto's vice president of strategy, said in a recent interview with POLITICO that IARC needed an external investigation into its workings to understand whether its assessment on glyphosate was structurally sound.

"When an organization such as IARC is given authority, with that comes a responsibility ... to be objective, transparent, thorough and fair," he said. "IARC has violated each and every one of those responsibilities and that should be troubling to anyone who is interested in preserving sound science."

"At least in this instance, their process was corrupted apparently with individuals who have an agenda," he said.

One official at IARC who did receive the raw data from the Greim study was Rusyn, a scientist based in the U.S. who runs a laboratory that tries to understand why chemicals cause cancer in rodents. In a February 27, 2015, email, IARC's Guyton asked Rusyn whether he would like to include the Greim data in IARC's glyphosate review.

Rusyn replied by casting doubt on the relevance of the Greim study.

"This is an interesting polemical piece," he said in a reply email. "It does not surprise me that when under pressure the industry can 'muster' a relevant publication that goes from submission to acceptance in as little as 7 weeks," he added, appearing to draw links between the publication of the study and the interests of Monsanto.

"I am confident that the IARC monograph will be much more comprehensive and balanced," he noted at the time.

Rusyn told Guyton to pass on "facts" from the Greim study to IARC's sub-group 3, which Jameson chaired. Jameson never received the information, according to his deposition.

Rusyn declined to comment directly on Jameson's comments in the deposition.

Questioning the data

Rusyn said that the Greim study "fell in a pretty wide gray zone" as it lacked data on matters such as statistical methods, choice of doses, body-weight gain and survival data of rats.

Greim, who conducted the 2015 study on glyphosate, said in an interview that it would have been useful for IARC to fully analyze the data in his study.

"In the light of the conclusions of other institutions which are known and do their work in a proper way and came to a negative result, I can only say that I at least don't understand why IARC came to a positive result and says it is carcinogenic," Greim said. "To be modest, to be polite ... from my point of view they [IARC] made a mistake."

Others, however, say IARC's decision not to perform a deep analysis of the data was justified due to wider questions about the methodology underpinning the scientific studies that went into the Greim study.

“IARC only looks at studies of quality and sorts out all studies that are deemed not reliable, at least to a certain degree” — Anton Safer

"IARC only looks at studies of quality and sorts out all studies that are deemed not reliable, at least to a certain degree," said Anton Safer, an independent scientist at the University of Heidelberg who has done extensive research into the standards attached to industry-funded scientific studies.

"The claim from industry is that 'we are perfect and we are working to good laboratory practices,'" he said. "The truth is that there are violations which could lead to major questions arising of the studies used by industry."

UPDATED: This article was updated to clarify the type of case brought by the plaintiffs against Monsanto.