Glyphosate Roundup Paper Retracted After 25 Years

A contentious scientific study that asserted the weedkiller glyphosate, sold as Roundup, "does not pose a health risk to humans" has been officially withdrawn, 25 years after it appeared in print. The retraction follows serious ethical concerns about industry interference.

The move arrives eight years after a 2017 legal case determined that staff at chemical firm Monsanto had helped ghostwrite the assessment of the herbicide's safety.

Glyphosate and Roundup safety paper withdrawn

Published in Regulatory Toxicology and Pharmacology in 2000, the paper was written by Gary Williams, Robert Kroes and Ian Munro. It concluded that there was no evidence linking Roundup to cancer, endocrine disruption or toxicity in humans. It became one of the most frequently cited studies in scientific literature on glyphosate.

Its reversal now prompts significant questions over the safety of Roundup.

Monsanto launched Roundup in 1974, while Bayer acquired the herbicide in 2018. Bayer still says the chemical is safe when used as instructed.

"The retraction is based on several critical issues that are considered to undermine the academic integrity of this article and its conclusions," states Martin van den Berg, the journal's co-editor-in-chief, in a retraction notice issued in November 2025. Van den Berg said he received no reply when attempting to contact Williams, the study's only surviving author.

"This article has been widely regarded as a hallmark paper in the discourse surrounding the carcinogenicity of glyphosate and Roundup," van den Berg writes.

"However, the lack of clarity regarding which parts of the article were authored by Monsanto employees creates uncertainty about the integrity of the conclusions drawn."

Monsanto involvement and undisclosed research

One of the cited 'critical issues' is that the article's evaluations of the chemical's role in cancer and genetic toxicity relied exclusively on unpublished Monsanto studies. Numerous other long-term studies that had already been completed when the review was prepared were left out.

The absence of independence among the authors "raises serious ethical concerns regarding the independence and accountability of the authors in this article", van den Berg says in the notice. He also cites the failure to reveal Monsanto employees' participation and any financial payment the authors may have received from the company.

Glyphosate is among the world's most extensively used herbicides. It is bought by both industrial farmers and domestic gardeners to eliminate unwanted plants.

In farming, the chemical has been marketed alongside 'Roundup Ready' crops: plants genetically modified to withstand glyphosate. These currently include soya, maize, oilseed rape, sugar beet, cotton and lucerne.

This genetic modification enables farmers to apply glyphosate widely over fields, destroying plants without built-in resistance while leaving the crops unharmed.

Health concerns and Roundup litigation

Concerns are increasing about the chemical's potential effects on human health, as well as its wide-ranging consequences for other parts of natural and human ecosystems.

Harvard scientist Naomi Oreskes found that the retracted study has been referenced in over 800 academic papers, dozens of government documents and several Wikipedia articles. She notes that many large language models now draw on Wikipedia for information.

In 2015, the World Health Organization's International Agency for Research on Cancer classified glyphosate as a probable carcinogen, largely on the basis of animal studies. Other health agencies and organisations, however, disagree.

Robust research that is genuinely independent will be necessary to establish whether glyphosate creates a genuine danger to people.

Bayer has so far paid $10 billion over lawsuits concerning Roundup's possible carcinogenicity that were outstanding in 2020, with more than 67,000 cases yet to be heard.

The original study and the retraction notice appear in Regulatory Toxicology and Pharmacology. Science has published the review examining the effect of the retracted paper.