Regulatory Toxicology and Pharmacology Retracts Influential 2000 Paper
The journal Regulatory Toxicology and Pharmacology has formally retracted a 2000 paper long cited as evidence that Monsanto's Roundup herbicide and its active ingredient, glyphosate, do not cause cancer. Editor in chief Martin van den Berg said the decision was driven by “serious ethical concerns regarding the independence and accountability of the authors of this article and the academic integrity of the carcinogenicity studies presented.”
The Paper and Its Impact. The article, titled Safety Evaluation and Risk Assessment of the Herbicide Roundup and Its Active Ingredient, Glyphosate, for Humans, concluded there were no cancer, reproductive, or endocrine-development risks from glyphosate-based products. Because the three listed authors—Gary Williams, Robert Kroes and Ian Munro—were presented as independent academics, regulators and industry defenders frequently cited the paper in assessments and debates over glyphosate safety.
Evidence of Company Involvement. Litigation in the United States brought internal Monsanto documents to light that contradict the paper's appearance of independence. Emails and corporate files show Monsanto personnel discussed the study, celebrated its publication, and described their own significant roles in data collection, review and relationship building with the named authors. One email from Lisa Drake, a then-Monsanto government affairs official, listed seven Monsanto employees she said had worked “over three years of data collection, writing, review and relationship building with the papers’ authors.”
Other internal messages included proposals to give Roundup-logo polo shirts to contributors and praise from senior executives. A 2015 email by Monsanto scientist William Heydens suggested that Monsanto staff could "ghost-write" papers that outside scientists would edit and sign, adding: “Recall that is how we handled Williams Kroes and Munro 2000.” Those communications were cited in jury trials that produced multi‑billion dollar verdicts for plaintiffs who alleged Roundup exposure caused cancer.
“The publication by independent experts of the most exhaustive and detailed scientific assessment ever written on glyphosate … was due to the perseverance, hard work and dedication of the following group of folks,” Lisa Drake wrote in a May 2000 email, listing Monsanto staffers she credited.
Responses From Bayer and Regulators. Bayer, which acquired Monsanto in 2018, acknowledged the retraction but said the original paper disclosed Monsanto’s contribution in its acknowledgments, noting “key personnel at Monsanto who provided scientific support.” The company reiterated its position that the large majority of published glyphosate studies did not involve Monsanto and cited regulatory consensus that glyphosate can be used safely as directed.
An Environmental Protection Agency spokesman said the agency was aware of the retraction and that it "has never relied on this specific article in developing any of its regulatory conclusions on glyphosate." The EPA noted it has reviewed more than 6,000 studies across disciplines and said its updated human health risk assessment—described by the agency as using "gold standard science"—will be released for public comment in 2026 and will not depend on the retracted paper.
Why the Retraction Matters. Editor van den Berg said concerns included misrepresentation of authorship, undisclosed contributions by the study sponsor, potential conflicts of interest, and the paper’s reliance on unpublished, company-conducted studies while discounting other published research. Legal advocates and plaintiffs’ lawyers called the retraction overdue, arguing it illustrates how industry influence can distort the peer-review record and public health debate.
Ongoing Legal And Public-Health Debate. The retraction arrives while thousands of lawsuits alleging that Roundup causes non‑Hodgkin’s lymphoma and other cancers remain active in U.S. courts. The issue also intersected with a recent brief by the U.S. solicitor general urging the Supreme Court to consider Bayer's argument that federal pesticide law pre-empts certain state-law failure-to-warn claims.
Current Status Of Key People. Gary Williams could not be reached for immediate comment. New York Medical College said in 2017 it found no evidence that any faculty member violated policies on ghostwritten work; the two other listed authors, Robert Kroes and Ian Munro, are deceased.
Takeaway. The retraction underscores the importance of transparency about authorship, sponsorship and data sources in scientific publishing—especially when studies influence regulatory decisions and public health litigation.
