Influential article claiming glyphosate isn’t carcinogenic retracted by scientific journal

A “hallmark paper” arguing that glyphosate isn’t carcinogenic has been retracted by the peer-reviewed journal Regulatory Toxicology and Pharmacology, 25 years after its publication, over concerns that employees from the American firm Monsanto may have partially ghostwritten the article and that its listed authors — one of them a former senior official at Health Canada — “may have received financial compensation” from the company.

The article evaluated the safety of Roundup and its active ingredient glyphosate. The herbicide was originally manufactured by Monsanto, before the company was acquired by the German pharmaceutical and biotech giant Bayer AG in 2018.

The reasons behind the retraction were outlined in a 1,050-word statement from the journal, which said the article’s conclusions on cancer and glyphosate were “solely based on unpublished studies from Monsanto” and that the authors had ignored “multiple other long-term chronic toxicity and carcinogenicity studies” completed by 1999, when the paper was submitted.

Litigation in the U.S. has “revealed correspondence from Monsanto suggesting that the authors of the article were not solely responsible for writing its content,” according to the statement. “It appears from that correspondence that employees of Monsanto may have contributed to the writing of the article without proper acknowledgment as co-authors.”

The three authors behind the retracted article “may have received financial compensation from Monsanto for their work on this article, which was not disclosed as such in this publication,” the statement continues, also citing correspondence from litigation.

It goes on to note the study’s influence on the long-running controversy surrounding glyphosate: it was “widely regarded as a hallmark paper” and a “cornerstone in the assessment of glyphosate’s safety.”

“The paper had a significant impact on regulatory decision-making regarding glyphosate and Roundup for decades…. The concerns specified here necessitate this retraction to preserve the scientific integrity of the journal.”

The statement stressed that the retraction “does not imply a stance on the ongoing debate regarding the carcinogenicity of glyphosate or Roundup.”

The journal’s handling co-editor-in-chief reached out to the only surviving author — Gary M. Williams of the Department of Pathology at New York Medical College — to seek an explanation, but he didn’t respond.

A spokesperson for New York Medical College told the NB Media Co-op that “Dr. Williams retired from NYMC in 2018, and unfortunately, we do not have his current contact information.”

The other authors were Robert Kroes of the University of Utrecht, who died in 2006; and Ian C. Munro, of the Mississauga-based firm Cantox Health Sciences International, who died in 2011.

Munro’s obituary describes him as a world-renowned scientist who held senior roles at Health Canada, including director of the Bureau of Chemical Safety and director general of the Food Directorate, Health Protection Branch.

“Munro was responsible for research and standard setting activities of the Branch related to microbial and chemical hazards in food and the nutritional quality of the Canadian food supply,” the obituary states.

He also served on “numerous national and international committees, including those of the World Health Organization, the International Agency for Research on Cancer and the U.S. National Academy of Sciences.” Munro was among the “founding shareholders of Cantox in 1985 and President from 1990 to 2006.”

This week, the administration of U.S. President Donald Trump threw its support behind Bayer in the Supreme Court, as the company faces thousands of lawsuits related to glyphosate’s alleged cancer risks.

Forestry companies in New Brunswick spray chemicals including glyphosate over softwood plantations to inhibit the growth of other plants, a longstanding source of controversy.

Activists point to research such as a 2019 study that links glyphosate-based herbicides to an increased risk of non-Hodgkin lymphoma.

Regulators including Health Canada consider glyphosate safe for humans in small amounts, in accordance with label directions, and the provincial Department of Environment has stated that the pesticide use in New Brunswick is tightly regulated.

Earlier this year, senior government officials told MLAs that restrictions on herbicide spraying recommended by an all-party legislative committee in November 2021 and mandated by Premier Susan Holt hadn’t yet been implemented.

About 15,000 hectares are sprayed annually in New Brunswick, according to the Department of Natural Resources.

David Gordon Koch is a journalist with the NB Media Co-op. This reporting has been made possible in part by the Government of Canada, via the Local Journalism Initiative.