Is Glyphosate Safe? The Disagreement Between US Regulators and the WHO
Glyphosate is the most-used herbicide in the world. It’s also the most argued-over pesticide ever sold. The fight isn’t about whether it kills weeds (it does, very well). It’s about what it does inside a human body at the doses people pick up day to day. And the answer depends entirely on which scientific body you ask.
Glyphosate is one chemical within the broader pesticide exposure picture, but it’s the one with the most public attention, the most contested science, and a legal record running to millions of pages of internal industry documents.
The US Environmental Protection Agency says glyphosate is “not likely” to cause cancer in humans. The World Health Organization’s International Agency for Research on Cancer (IARC for short) said in its 2015 Monograph 112 that glyphosate is “probably” carcinogenic. Both groups looked at largely the same research and reached opposite conclusions. Neither has budged since. That split, and what it reveals about how pesticide regulation works in this country, is the part of the glyphosate story most worth understanding.
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What glyphosate is and how it ended up everywhere
Glyphosate was patented by Monsanto in 1971 and sold under the Roundup brand starting in 1974. It kills plants by blocking a specific enzyme (EPSPS) that plants need to make their own amino acids (the building blocks of protein). Humans don’t have that enzyme. That’s the foundation of the industry’s argument that glyphosate is safe for people. The catch is that a lot of bacteria do have that enzyme, including many of the bacteria living in human guts. That part of the picture tends to get left out when the industry makes its safety pitch. Glyphosate is one type of pesticide among several; the pesticide types breakdown covers the other major herbicide and insecticide classes and how they differ from one another.
The product went from a niche herbicide to the global standard through two strategic ways. First, Monsanto engineered crops to survive glyphosate spraying, the Roundup Ready line, starting with soybeans in 1996. Second, the company patented the seed and required farmers to buy it annually rather than save it. By 2014, roughly 90 percent of US soy, corn, and cotton acres were planted in Roundup Ready varieties, and US glyphosate use had risen roughly 15-fold from 1992 levels.
The second use that drives most dietary residue is pre-harvest desiccation. Wheat, oats, barley, and some legumes are sprayed with glyphosate shortly before harvest to dry the crop. This isn’t a Roundup Ready application. The crop isn’t engineered to survive it. The grower sprays the chemical specifically to kill the crop a few days early, so it dries down evenly and the combine can move through cleanly. Residues from that application end up in cereal, bread, oats, and beer.
The IARC versus EPA split
In 2015, IARC’s working group of independent scientists from around the world did a full review of the published research on glyphosate and ended up with three big findings. The first was that research on humans (mostly farmworkers who’d developed a blood cancer called non-Hodgkin lymphoma) showed a real but limited link, and the researchers said they wanted to see more human studies before they could be certain. The second finding was much clearer: glyphosate caused cancer in lab animals at consistent enough rates that there was no honest way to dismiss it. The third was what carried the most weight in the decision. In studies of human cells exposed to glyphosate, the chemical damaged DNA and produced the kind of cellular stress that’s known to lead to cancer. Put those three findings together and you get the Group 2A “probably carcinogenic” classification.
EPA’s own review reached the opposite conclusion. The agency finalized it in 2020 (the document is the Interim Registration Review) and has stood by it since. How did two reviews of the same chemical end up so far apart? EPA gave more weight to unpublished studies submitted by the industry than IARC did. The agency used different statistical thresholds when looking at the same tumor data in lab animals. And it dismissed the human worker studies that IARC found compelling. The result of all that: EPA’s conclusion that glyphosate isn’t likely to cause cancer in humans, which is what keeps the chemical legal on US food crops today.
A federal court did weigh in. In 2022, the US Ninth Circuit Court of Appeals threw out parts of the EPA’s health risk assessment for glyphosate and sent it back to the agency for another look, finding that the EPA hadn’t adequately backed up its position. The EPA has not produced a new final answer since.
International regulators have split mostly along similar lines. The European Union renewed glyphosate’s approval for ten years in November 2023, though member states couldn’t reach a qualified majority either way and the European Commission had to make the decision itself. Austria, Croatia, and Luxembourg voted against the renewal; France and Germany were among the countries that abstained. The renewal banned pre-harvest desiccation use in the EU, which is the use that drives most dietary residue. Mexico tried to phase out glyphosate by 2024 but officially voided its restrictions in February 2025 after a USMCA trade dispute panel ruled against the country. Sri Lanka, Vietnam, Saudi Arabia, and Thailand have all moved toward partial or full bans, though enforcement in each country varies.
The Bayer litigation
Bayer bought Monsanto in 2018 for $63 billion. Within weeks of closing, the first major Roundup verdict came down: $289 million for Dewayne Johnson, a school groundskeeper who developed non-Hodgkin lymphoma after years of Roundup use. That verdict set a tone.
As of early 2026, Bayer has paid more than $11 billion in settlements and jury verdicts across more than 192,000 lawsuits, with thousands of cases still pending. The company continues to deny that Roundup causes cancer while paying out settlement after settlement. In February 2026, Bayer announced a proposed $7.25 billion class action settlement designed to resolve both current and future Roundup claims, and has set aside roughly $16 billion total for Roundup litigation.
The lawsuits also turned up something useful for the public: the Monsanto Papers. These are internal company documents that came out during legal discovery. They showed Monsanto staff writing scientific papers and putting outside academics’ names on them as the authors (one of those papers was formally retracted by the publishing journal in 2025). They showed internal acknowledgement, in writing, that full Roundup formulations might be more toxic than glyphosate alone (something the company had publicly denied for years). And they showed a deliberate, documented effort to manage relationships with specific EPA staffers who oversaw glyphosate’s review. Investigative journalist Carey Gillam continues to cover this at The New Lede.
The Monsanto Papers don’t prove that glyphosate causes cancer. They do show that the science used to support EPA’s position was shaped, in part, by the manufacturer of the chemical, and that fact is part of why the regulatory-capture concern around this compound is louder than for most others.
What the body does with glyphosate
The non-cancer side of the glyphosate question is less settled and less politically charged, but the research is moving in a direction that matters for everyday exposure.
The gut microbiome story is the one with the most active research. Glyphosate’s mechanism (blocking the shikimate pathway that bacteria need to make essential amino acids) affects many of the bacterial species that live in the human gut. Studies have shown shifts in the balance of beneficial and harmful gut bacteria after glyphosate intake, including reduced populations of bifidobacteria and lactobacilli (two of the main groups associated with healthy digestion and immune function). Whether those shifts produce measurable downstream health effects in people is the next research question, and the early signals suggest connections to inflammation and immune dysregulation.
Liver function comes up in several long-term animal studies. Rats fed low doses of glyphosate-based herbicide over years showed changes in liver enzyme markers and signs of fatty liver disease at doses below what regulators consider safe. The relevance to humans isn’t fully worked out, but it’s the kind of finding that wouldn’t show up in the short-term studies industry typically submits for registration.
Reproductive and hormone-system effects are an active research area. Multiple studies have documented changes in reproductive function in lab animals (sperm quality reductions in males, hormone disruptions in females, effects on early pregnancy in rodent models). Cell-based research suggests glyphosate-based formulations interfere with hormone signaling at low doses. The human evidence is still developing, but the lab findings are consistent enough that several reviews have called for human studies to be prioritized.
The harder question across all these areas is whether the lab findings translate to real health effects in people at the doses we actually pick up from food. That’s where the science is still working. What’s clear is that “no known harm at current exposure levels” (the official US framing) is closer to “we haven’t proven harm yet” than to “we’ve proven safety.”
Glyphosate now shows up in the urine of roughly 80 percent of US adults tested in CDC’s regular national health survey. Levels go up in people who eat more conventional grain products, and down in people eating mostly organic. The pattern shows the chemical is in the American diet at every income level and in every region. The intake is real and continuous. Whether the levels in any one person are doing harm is the question the science is still working to answer, and the precautionary approach (reduce exposure where you reasonably can) is the one most public health researchers outside of regulatory agencies are recommending.
The 2026 Farm Bill liability shield fight
In late 2025, pesticide manufacturers pushed for language in the 2026 Farm Bill that would block a key type of state lawsuit. The lawsuits in question are “failure to warn” cases, which is what most of the Roundup cancer suits are: people arguing that Monsanto/Bayer should have warned them the product could cause cancer. The proposed language would have said that if the federal label doesn’t require a specific warning, states can’t let people sue over its absence. If that had passed, it would have ended most Roundup cancer cases going forward and removed the main legal pressure on Bayer to disclose what it knew about glyphosate’s risks.
The shield language was stripped from the House version of the bill on April 30, 2026, by an amendment that passed 280-142. The bill went to the Senate, which is writing its own version. The shield language can still come back in the Senate’s bill, in conference committee, or in separate legislation. The current Farm Bill extension expires September 30, 2026.
As of May 29, 2026, the liability shield isn’t law, the House has voted against it, and the fight is ongoing. The procedural detail isn’t really the point. The point is that the legal system has been the main mechanism producing public disclosure on this chemical, and the industry is actively working to shut that mechanism off. For ongoing coverage, Civil Eats and The New Lede have reliable reporting.
What reduces glyphosate intake
If you want to drop the amount of glyphosate showing up in your body, two changes have the biggest impact. The first is swapping conventional oat products (oatmeal, granola, oat-based cereal) for organic versions or for products carrying the Glyphosate Residue Free label. The second is doing the same for conventional wheat products (bread, pasta, flour-based baked goods). Both of those changes target the pre-harvest desiccation residue, which is the biggest single source of dietary glyphosate for anyone who isn’t handling the chemical at work.
Conventional soy, corn, and the processed foods made from them are the next-biggest source. Going organic on those, or just cutting back on processed foods formulated around them, drops the amount of glyphosate showing up in your urine even further.
If you don’t use Roundup or glyphosate-containing weed killers at home, your neighbors might. Lawn and garden use is its own pathway, with pet and child contact involved.
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This page is reviewed periodically as new research emerges. Content reflects current scientific understanding of toxin-related health topics.
Last reviewed: June 2026