New study finds glyphosate weedkillers cause multiple cancers in rats at "safe" doses
By isabelle // 2025-06-12
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  • A new study reveals that glyphosate-based weedkillers like Roundup can cause multiple cancers in rats at doses that regulators consider safe.
  • Tumors appeared in their blood, skin, liver, and other organs, with prenatal exposure proving to be especially deadly.
  • Bayer, facing thousands of lawsuits, is lobbying for legal immunity instead of pulling the product from the market.
  • Regulators continue defending glyphosate despite WHO labeling it a probable human carcinogen, ignoring risks from commercial formulations.
  • The study challenges industry-backed safety claims, raising urgent questions about continued glyphosate use in food and public spaces.
A bombshell new international study has exposed the deadly truth about glyphosate-based weedkillers like Roundup: They cause multiple cancers in rats at doses currently deemed "safe" by regulators. The peer-reviewed research, published in Environmental Health, found tumors in the blood, skin, liver, thyroid, and other organs, with prenatal exposure proving especially devastating. The findings come as Bayer, the corporate giant behind Roundup, fights tooth and nail to avoid accountability for the thousands of cancer lawsuits linked to its toxic product. For decades, Monsanto (now owned by Bayer) has insisted that glyphosate is harmless, even as independent scientists and victims have sounded the alarm. Now, the latest science confirms what whistleblowers have warned all along: Glyphosate is a carcinogen, and regulators have failed to protect the public.

Glyphosate and Roundup trigger deadly tumors

The study, conducted by researchers from Italy’s Ramazzini Institute and Boston College, exposed rats to glyphosate and two commercial formulations, Roundup Bioflow (used in Europe) and Ranger Pro (a U.S. generic version), over two years. The doses tested included the European Union’s "acceptable daily intake" (ADI) of 0.5 mg/kg of body weight per day, as well as higher levels. The results were horrifying. Rats developed tumors in multiple organs, including their blood (leukemia), skin, liver, thyroid, nervous system, ovaries, and mammary glands. Prenatal exposure was particularly deadly, with 40% of leukemia deaths occurring in rats under one year old in an alarming indicator of how glyphosate harms developing life. "Our study showed carcinogenic effects in rats at doses that are currently considered safe," said Dr. Daniele Mandrioli, the study’s lead author and director of the Cesare Maltoni Cancer Research Center.

Bayer’s desperate legal battle to avoid accountability

This damning research arrives as Bayer faces tens of thousands of lawsuits from cancer victims who blame Roundup for their illnesses. The company has already paid out $11 billion in settlements but is now lobbying for legal immunity to shut down future claims. In April, Bayer petitioned the U.S. Supreme Court to block existing lawsuits and prevent new ones, arguing that federal pesticide law (FIFRA) should override state-level failure-to-warn claims. Meanwhile, Bayer has threatened to stop selling Roundup in the U.S. unless it gets protection from litigation. Corporate greed couldn’t be clearer: Instead of pulling this poison from shelves, Bayer is fighting to keep profiting while victims suffer. Despite the World Health Organization’s 2015 classification of glyphosate as a "probable human carcinogen," the EPA continues to defend it, claiming it poses "no risks to human health" when used as directed. This new study obliterates that claim. Even more disturbing, the research suggests that glyphosate-based herbicides may be more carcinogenic than glyphosate alone, likely due to toxic additives in commercial formulations. Yet regulators refuse to test these real-world products, instead relying on industry-funded studies of glyphosate in isolation. With Bayer scrambling for legal loopholes and regulators asleep at the wheel, the burden falls on the public to demand change. If a chemical causes cancer in lab animals at "safe" doses, why is it still sprayed on our food, parks, and playgrounds? Sources for this article include: ChildrensHealthDefense.org TheNewLede.org EHJournal.BioMedCentral.com ChildrensHealthDefense.org
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