A scientific paper once used to defend Monsanto’s Roundup against cancer fears has been formally withdrawn, sparking renewed debate about research independence and corporate influence in science. The journal Regulatory Toxicology and Pharmacology retracted the 2000 study titled Safety Evaluation and Risk Assessment of the Herbicide Roundup and Its Active Ingredient, Glyphosate for Humans, after editors cited “serious ethical concerns regarding the independence and accountability of the authors” and questions about the integrity of the cited carcinogenicity studies.
The paper, authored by Gary Williams, Robert Kroes, and Ian Munro—three scientists not employed by Monsanto—had been invoked by regulators, including the U.S. Environmental Protection Agency (EPA), as evidence that glyphosate-based weed killers are not associated with cancer or other health risks. The appearance of independent researchers lent the work credibility and helped Monsanto present Roundup as a safe product in the face of conflicting evidence.
However, over the past decade, internal Monsanto documents uncovered in U.S. litigation revealed the company’s involvement in shaping the paper’s conclusions. Email communications show executives discussing the research and praising the scientists’ work as part of a broader strategy labeled “Freedom to Operate.” In one note, a Monsanto government affairs official celebrated the publication as a pivotal reference for the company’s products, noting plans to use it to differentiate Roundup from generics worldwide. Other messages described providing memorabilia—like Roundup polo shirts—to team members involved in the research, and one executive urged keeping leadership informed as public relations materials were prepared.
In 2015, Monsanto scientists discussed ghostwriting another study, proposing that outside researchers edit and sign the work—an approach reminiscent of the Williams–Kroes–Munro paper. These revelations surfaced prominently in court trials where plaintiffs alleging cancer linked to Roundup obtained substantial damages against Monsanto, now part of Bayer since 2018.
The retraction statement from Van den Berg cited concerns about authorship, possible misrepresentation of contributions, sponsor influence, and potential conflicts of interest. It also noted that the glyphosate safety conclusions relied largely on Monsanto’s unpublished studies, downplaying external, published research.
Monsanto—now Bayer—acknowledged that the paper’s involvement was disclosed in the acknowledgments and claimed the majority of glyphosate research shows no carcinogenic risk when used as directed. The EPA contends it has never relied on the Williams–Kroes–Munro study in forming regulatory conclusions and emphasizes that its current assessment is based on a broad review of thousands of studies using rigorous standards. An EPA spokesperson indicated the ongoing evaluation will be released in 2026 and will not hinge on the retracted work.
Commentary from legal figures involved in the Roundup cases has framed the Williams–Kroes–Munro paper as a clear example of how ghostwriting, selective citing, and biased interpretation can undermine peer review and scientific credibility. Advocates for stronger safeguards argue that this episode underscores the need for essential transparency in authorship and funding. Critics, meanwhile, may question the blanket rejection of decades of glyphosate research or debate the overall safety profile of Roundup when used correctly.
This development arrives as a broader policy backdrop: the U.S. government considered Bayer’s effort to limit thousands of lawsuits against Roundup, arguing that federal pesticide law preempts certain state-level claims. Plaintiffs maintain that Roundup exposure contributed to non-Hodgkin’s lymphoma and other cancers.
This report is co-published with The New Lede, a journalism project from the Environmental Working Group.
