Court documents made public this week reveal claims of Monsanto employees ghostwriting scientific reports that U.S. regulators used to determine if the biotech company’s Roundup weed killer causes cancer.

Roundup — the chemical giant’s flagship product whose active ingredient, glyphosate, is the most widely used weed killer worldwide — has long been touted safe in industry-funded research.

This assumption, however, has been challenged by a federal court case filed by farmers and other parties based on findings from the International Agency for Research on Cancer, or IARC, a World Health Organization branch, claiming that Roundup could lead to a form of cancer known as non-Hodgkin’s lymphoma.

What Unsealed Court Docs Reveal

Court files were unsealed by Judge Vince Chhabria last March 14. The federal mass litigation covers around 60 lawsuits with several hundreds more pending in state courts, according to the plaintiffs’ attorney Aimee Wagstaff.

Plaintiffs in the ongoing litigation alleged that Monsanto’s toxicology manager ghostwrote sections of a 2013 study published under the names of several scientists, while his boss is said to have ghostwritten parts of a 2000 study.

Records also indicated that a senior official at the Environmental Protection Agency helped “kill” an agency investigation into the herbicide’s key chemical. Certain disagreements within the agency over its safety assessment also surfaced.

According to the documents, Monsanto executive Dan Jenkins said in a 2015 email that former EPA deputy director Jess Rowland told him: “If I can kill this, I should get a medal.” Rowland was said to be pertaining to a glyphosate study being conducted at the Department of Health and Human Services, a different federal agency.

Rowland is now retired and is not a defendant in the mass litigation, but after leaving his post last year, he figured in over 20 U.S. lawsuits accusing Monsanto of failing to warn its consumers and regulators of the herbicide’s risks.

Just last March 10, a California state court judge ruled that the state could classify glyphosate as a cancer risk, Reuters reported.

The judge rejected Monsanto’s argument that the herbicide should not be incorporated in a list created by a voter-approved ballot initiative requiring explicit warnings for consumer goods containing potentially cancer- or birth defect-causing substances.

Monsanto’s Statement

In a phone interview with Bloomberg, Monsanto VP for global strategy Scott Partridge said it would be “remarkable” if their firm could perform such maneuverings at the EPA during the Obama administration.

“It’s not an effort to manipulate the system,” Partridge said of the revealed emails between Monsanto and the federal agency, deeming them part of “a natural flow of information.”

In an official statement, Monsanto shot down allegations that glyphosate leads to cancer in humans, calling the charges “inconsistent” with decades of “comprehensive safety reviews by the leading regulatory authorities around the world.”

Unsettled Science

Lawyer Robin Greenwald, who is involved in the litigation, said that “superb scientists” across the world would not agree with Monsanto and some official evaluations on its product.

Monsanto remains strong in its defense of glyphosate amid findings from the international cancer agency. A number of agencies, however, have disagreed with the IARC’s conclusion and played down cancer-related concerns.

The European Food Safety Authority, for instance, concluded in its 2015 evaluation of glyphosate’s use on weed in different crops that the chemical is “unlikely to pose a carcinogenic hazard to human.”

Last year, a UN report cited evidence indicating that administering glyphosate and associated products at doses of 2,000 milligrams per kilogram of body weight (or higher) did not lead to toxic impacts in certain studies involving animals.

Safety issues around glyphosate have hounded America in the face of intense genetic engineering. Over the last 20 years, Monsanto has genetically modified corn, soybeans, and cotton so it is easier to spray them with the weed solution. About 220 million pounds of glyphosate, according to the New York Times, were used in 2015 alone.