After a quarter of a century, one of the pillars on which the defense of glyphosate was based collapses. The prestigious journal Regulatory Toxicology and Pharmacology has formally withdrawn the 2000 study by Williams, Kroes and Munro, which for 25 years was considered a point of reference in evaluating the safety of the most used herbicide in the world.
The decision, announced on 5 December 2025, opens a disturbing glimpse into the mechanisms with which the chemical industry has influenced the scientific debate and regulatory decisions in Europe and around the world.
The reasons for the retraction
What was supposed to be an independent study on the safety of glyphosate and its commercial product Roundup now turns out to be a textbook case of scientific ghostwriting. During litigation in the United States, documents emerged showing that Monsanto employees contributed to the writing of the article without ever being named as co-authors. A practice that undermines the very concept of independent scientific research.
The reported authors – Gary M. Williams, Robert Kroes and Ian C. Munro – also received financial compensation from Monsanto for their work, which was never disclosed in the publication. An omission that raises very serious questions about the objectivity of the entire evaluation. The magazine’s editor-in-chief Martin van den Berg attempted to contact the only living author, Gary M. Williams, but never received a response.
Perhaps the most serious aspect concerns the methodology used. The review was based exclusively on unpublished studies provided by Monsanto, completely ignoring at least five important studies on the long-term carcinogenicity of glyphosate already available in 1999, the year the article was written. These included studies conducted by Japanese and Indian institutes that examined the effects of the herbicide on mice and rats for periods of up to 24 months.
The authors admitted that they were aware of other unavailable studies, but did not explain why they had not attempted to include them in their analysis. A choice that today appears anything but random: limiting itself to the Monsanto studies, the review could easily conclude that the product was not carcinogenic.
The review then used an approach called “weight of evidence”, a valid methodology in itself which involves evaluating all the available studies. But when the evidence is selected upstream, systematically excluding those that the sponsor does not like, the entire interpretative castle collapses. As the retraction notification points out, potential biases introduced by Monsanto’s undisclosed contributions and exclusion of existing studies have likely distorted the entire interpretation of the data.
At the end it reads:
In light of the above-mentioned issues, the (co)editor-in-chief has lost confidence in the findings and conclusions of this article and believes that its retraction is necessary to preserve the integrity of the journal.
Twenty-five years of decisions based on rotten foundations
The consequences of this scientific deception are incalculable. The article has influenced regulatory decisions on glyphosate in Europe and around the world for decades. Every time the European Union has had to decide whether to renew authorization to use the herbicide, this review has been cited as proof of its safety. Thousands of tonnes of glyphosate were spread across European fields based on findings that we now know were constructed with direct input from the manufacturing company.
In the withdrawal notification, editor-in-chief Martin van den Berg is keen to point out that the decision does not imply a position on the carcinogenicity of glyphosate itself, but derives from the application of the guidelines of the Committee on Publication Ethics. A necessary clarification, but it does not erase the fact that for 25 years that review contributed to shaping the scientific consensus on a controversial product.
What changes now?
The formal retraction of this study opens up new scenarios. European regulatory authorities will inevitably have to re-evaluate decisions made based on scientific literature that now turns out to be compromised. Even the ongoing lawsuits against glyphosate producers – Bayer acquired Monsanto in 2018 – could find in this retraction a new element in favor of the plaintiffs.
But above all, this case reminds us that the battle for public health and the environment is also fought on the terrain of scientific integrity. When the line between independent research and corporate public relations becomes too thin, the very credibility of science is compromised. And with it, our ability to make informed decisions about the risks we are willing to accept.
The issues have finally come to a head.
