Glyphosate Safety Claims Collapse: Health Canada Must Act
New science and a retraction expose deep problems in glyphosate’s safety record
A major scientific paper long used to justify claims that glyphosate — the herbicide found in Roundup® — does not cause cancer has now been formally retracted by Regulatory Toxicology and Pharmacology. The Williams, Kroes, and Munro review, published in 2000, was relied upon by regulators worldwide — including Health Canada’s Pest Management Regulatory Agency (PMRA) — to support claims of glyphosate’s safety. The retraction reveals that the paper drew on unpublished industry data and raises serious concerns about conflicts of interest and authorship, weakening the scientific foundation for past regulatory decisions.
This development casts a harsh light on how Canada assessed glyphosate. When PMRA re-evaluated the herbicide in 2017, it based its cancer conclusion on six studies. Three of these were included in the now-retracted Williams review. Of the remaining studies, one showed “equivocal evidence of oncogenicity” (meaning the cancer finding was uncertain), leaving only two studies supporting PMRA’s conclusion that glyphosate is “unlikely to pose a human cancer risk.”
Even more troubling: PMRA did not conduct an independent review of all six studies. Instead, it relied on assessments by foreign regulators — many of which echoed or relied on the same now-discredited Williams review. PMRA even acknowledged that not all carcinogenicity studies were submitted for its evaluation. The agency’s reliance on secondary summaries rather than primary data created a weak and circular evidence base that now appears scientifically untenable.
For years, Safe Food Matters, a Canadian charity focused on pesticide and GMO policy, has warned that PMRA’s approach was deeply flawed. In its legal challenges, the organization argued that PMRA failed to assess the unique risks of pre-harvest glyphosate use, which can leave residues directly on food crops, and failed to apply a required 10-fold safety factor to protect children. The Federal Court of Appeal agreed that PMRA had not followed its own guidance and ordered the agency to reconsider. PMRA dismissed the objections again, and a second legal challenge — supported by Friends of the Earth Canada and Environmental Defence — is now before the courts.
Meanwhile, new research has intensified global pressure. The Ramazzini Institute’s large-scale Global Glyphosate Study found evidence that glyphosate does cause cancer, yet PMRA has taken no action. At the same time, the U.S. EPA withdrew its health risk assessment after a federal court ruled its cancer conclusions were not supported by science. Europe has also moved to restrict pre-harvest use because of cancer and environmental concerns.
Taken together, the picture is clear:
– The scientific foundation PMRA relied on has been formally discredited.
– PMRA’s own reviewed studies include evidence of possible cancer risk.
– International regulators have reversed or reassessed their positions.
– Strong new independent research contradicts past safety claims.
Take Action
Minister of Health Marjorie Michel has a legal duty to ensure pesticides pose no risk of harm to Canadians. With the main review supporting glyphosate’s safety now retracted — and multiple studies raising credible cancer concerns — Canada no longer has a scientifically defensible basis to keep glyphosate on the market.
CHD Canada calls on the Minister to remove glyphosate from use in Canada and to order an independent, transparent, conflict-free review of all cancer evidence. Canadians should urge the Minister of Health to act now — the scientific uncertainty is too great, and the stakes far too high, to delay.
Sources:
National Observer – Ottawa glyphosate research raises cancer questions (Dec 11, 2025)
Safe Food Matters – The Tables Have Turned on Glyphosate for Health Canada (Dec 5, 2025)
Williams, Kroes, Munro – Regulatory Toxicology and Pharmacology (2000), RETRACTED: Safety Evaluation and Risk Assessment of the Herbicide Roundup and Its Active Ingredient, Glyphosate, for Humans
**************************************************************************************************************