A long-cited scientific study that shaped global views on the safety of glyphosate, the active ingredient in the widely used weedkiller Roundup, has been formally retracted, reigniting concerns about the chemical’s health risks.
Published in 2000, the study concluded that glyphosate did not pose a cancer risk to humans, despite earlier research suggesting possible links to the chemical.
For more than two decades, the paper was frequently referenced by regulators and scientists and became a key pillar in decisions that allowed the herbicide’s widespread use in agriculture and home gardening.
Last month, the journal Regulatory Toxicology and Pharmacology withdrew the study, citing serious ethical questions about the independence of its authors. Editor-in-chief Martin van den Berg said the study relied heavily on unpublished research conducted by Monsanto, the manufacturer of Roundup, and failed to adequately disclose potential conflicts of interest.
Glyphosate remains one of the most commonly used herbicides in the United States, applied to crops including soybeans, corn, wheat, and cotton, as well as specialty crops such as almonds.
The Environmental Protection Agency continues to classify the chemical as safe but is required to reassess its health impacts by 2026 following lawsuits from environmental, food-safety, and farmworker advocacy groups.
The retraction follows internal emails disclosed during litigation against Monsanto, now owned by Bayer, which suggest that company scientists were closely involved in drafting the 2000 study, even though it was presented as an independent scientific review.
Some emails revealed hopes that the paper would become the definitive reference on glyphosate safety.
Van den Berg said the lack of transparency regarding industry involvement, including possible financial compensation to the authors, undermined confidence in the paper’s conclusions.
The journal determined that acknowledgments of Monsanto’s “scientific support” were insufficient to meet ethical standards for disclosure.
The withdrawal has intensified scrutiny of glyphosate and added momentum to calls for stricter regulation of chemicals used in food production.
Public health historians note this case reflects a broader pattern of industry influence on scientific research, similar to practices previously seen in the tobacco and lead industries.
David Rosner, co-director of the Center for the History and Ethics of Public Health at Columbia University, said such conduct, where research outcomes are subtly steered to align with commercial interests, is widespread rather than isolated.
He emphasized that academic journals bear responsibility for enforcing stricter disclosure standards.
The journal’s decision followed requests from two Harvard University researchers, Sasha Kaurov and Naomi Oreskes, who called for a formal reassessment of the paper.
Their analysis found the study ranked among the top 0.1 per cent of most-cited academic publications on glyphosate, underscoring its outsized influence on science and regulation.
Oreskes noted that the study continued to be widely cited even after internal company emails raised questions about its independence.
She said the paper remained one of the most frequently referenced works on glyphosate safety long after concerns about its origins had surfaced.