Review 604: Glyphosate, Fire and Science

While our recent GMWatch Reviews have focused on major developments on the GM front, a huge amount has also been happening involving glyphosate – the herbicide GM crops have helped to make the most used in the world, being responsible for more than half of all global glyphosate use and 85-95% of the use in the major GM crop growing countries, like the United States, Brazil, and Argentina.

In future Reviews we’ll be looking at some of the big political and legal developments on the glyphosate front. But in this one, our focus is mainly on the science, with lots of new studies showing the multiple harms of glyphosate (SCIENCE ON GLYPHOSATE: LATEST RESEARCH); more evidence of the cornerstone of regulatory decision-making – glyphosate safety reviews – having been ghostwritten by Monsanto (FRAUDULENT BASIS OF GLYPHOSATE REGULATION); and some easily accessible discussions with researchers about the health harms of glyphosate (SCIENCE ON GLYPHOSATE: OVERVIEW).

The final section of our Review is about a very hot topic at the moment in our rapidly warming world: GLYPHOSATE, FORESTS AND FIRE. We look at the damaging use of glyphosate to convert wild public forestlands in the US and Canada into poisoned flammable tree farms; how this is occurring on a massive scale; and how the Forest Services of both the US and Canada rely on completely discredited evidence to justify this bombardment of forests with glyphosate. And needless to say, it is not just the forests of North America that are being assailed in this way, contributing to major biodiversity loss and greater vulnerability to wildfires.

SCIENCE ON GLYPHOSATE: OVERVIEW

Prof Antoniou: Why a glyphosate ban is long overdue

Over the last 14 years, Michael Antoniou, Professor in Molecular Genetics and Toxicology at King’s College London, has led a research group that has become a world leader in glyphosate toxicology, having conducted and published dozens of independent, peer-reviewed studies. Basing himself on the evidence they have helped uncover, Antoniou has concluded that governments are negligent, regulating systems corrupt, and a ban on glyphosate long overdue. He retired last year but continues to oversee research as Professor Emeritus and has continued his public education activities to increase awareness and push for action. In an interview for Wicked Leeks, he notes how regulators “set exposure limits based on studies of glyphosate alone. They have never required long-term toxicity studies on commercial formulations [like Roundup], which every person and every plant in the field is actually exposed to. Yet the evidence shows that these cocktails are much more toxic than glyphosate alone. The number of studies that demonstrate this are in the hundreds now. Let’s not forget the co-formulants are highly toxic in their own right and they can be carcinogenic as well.”

Glyphosate: The one pesticide everyone is exposed to and why it should be banned

In a video interview with Dr Rupy Aujla, host of The Doctor’s Kitchen, Prof Michael Antoniou discusses:
* What glyphosate is and how it works by blocking a crucial enzyme in plants and microbes.
* Why it was deemed safe and why new evidence suggests we may have underestimated its risks.
* The latest research linking glyphosate exposure to gut microbiome disruption, liver disease, and cancer.
* Which foods carry the highest residues and whether washing, peeling, or buying organic makes a real difference.
* How chronic exposure builds up in the body and what steps you can take to reduce your exposure today.

The dangers of glyphosate
In a video interview with the journalist James Corbett for The Corbett Report, Prof Michael Antoniou discusses the many toxic effects of glyphosate-based herbicides and explains why regulators have failed to protect people and nature from harmful exposures to these chemicals.

Glyphosate Science Webinar: Cancer, neurotoxicity and endocrine disruption
This 6 October webinar features Dr Daniele Mandrioli on recent findings from the Global Glyphosate Study, which revealed glyphosate weedkillers cause multiple types of cancer, and Dr Lianne Sheppard on the findings presented at the Seattle Glyphosate Symposium, which was attended by 70 leading researchers from around the world, and which culminated in the publication of a scientific Consensus Statement on the urgent need to address health harms of glyphosate. Register for the webinar here.

FRAUDULENT BASIS OF GLYPHOSATE REGULATION

Publisher investigating two more papers on glyphosate safety over ghostwriting claims
Retraction Watch reports that the academic publisher Taylor & Francis is investigating two papers about glyphosate following claims they were ghostwritten by Monsanto. The review comes after an Elsevier journal last year retracted a landmark safety review on glyphosate, which had been heavily relied on by regulators to support glyphosate safety, after court documents revealed that Monsanto employees wrote it but were not named as coauthors. A spokesperson for the publisher said it “recently received information related to two papers in Critical Reviews in Toxicology” – a 2015 review article led by toxicologist Helmut Greim of the Technical University of Munich and a 2013 paper by toxicologists Larry Kier and David Kirkland that support the safety of glyphosate.

EPA relied on influential glyphosate study even after learning it was ghostwritten
The US Environmental Protection Agency (EPA) has known for nearly a decade that the influential 2013 scientific paper by Kier and Kirkland that concluded glyphosate is safe was actually ghostwritten by Monsanto, according to the investigative journalist Nate Halverson. But the agency kept quiet about its discovery, informing neither the public nor other regulatory agencies abroad. The EPA went on to cite the compromised paper as evidence that glyphosate is safe to use in its 2020 assessment, despite its own internal investigation that concluded the research paper hid Monsanto’s role as an author. The European Food Safety Agency also cited the Kier and Kirkland study for its 2023 re-assessment of glyphosate that determined the herbicide is safe. Now, nearly ten years after the EPA concluded that the paper was ghostwritten, its publisher, Taylor & Francis, has opened its own investigation into the paper (see item above).

Approval of Roundup relies on industry‑funded reviews currently under investigation
New Zealand’s approval of Roundup – like that of the US and the EU – also relies on industry‑funded reviews currently under investigation for being ghostwritten by Monsanto. One of them has now been retracted and two are under investigation (see items above). This is explored in an excellent article by the researcher Alexander Kaurov that is relevant to all countries that have approved Roundup, as the industry uses basically the same data in its submissions for regulatory approvals globally. It was Kaurov, an expert in computational analysis of scientific discourse, who, together with the Harvard historian of science Naomi Oreskes, published the analysis that prompted the December 2025 retraction of the key safety review on glyphosate (Williams, Kroes, and Munro) after they highlighted how the heavily cited paper, ghostwritten by Monsanto, had hugely influenced global safety discourse and had a massive ongoing citation footprint.

Listen: How a fake study shaped 25 years of pesticide policy
In an excellent interview, Naomi Oreskes talks with Robyn Vincent about the significance of the retraction after 25 years of the Williams et al glyphosate safety review that became a cornerstone of regulatory decision making. The review was cited without caveat in hundreds of academic papers, and dozens of government documents from public health agencies around the world, even after internal Monsanto emails, released in 2017 litigation, revealed that Monsanto employees had ghostwritten it. Monsanto not only came up with the idea for the paper but recruited academics to put their name on it as if they were the authors and as if they were independent – which of course they weren’t. This is a form of fraud, Oreskes notes. The people whose names are on the paper are not, in fact, the authors.

Watch: Monsanto’s 5-step plan to make their “science” mainstream
In this 3-minute video, investigative journalist Nate Halverson breaks down how Monsanto got the EPA and other government regulators to rely on their secretly ghostwritten studies.

SCIENCE ON GLYPHOSATE: LATEST RESEARCH

Glyphosate-based herbicides cause neurobehavioral alterations, suggesting link to autism
In a study in rats, when pregnant mothers and their descendants were exposed to doses of glyphosate and two glyphosate-based herbicides (Roundup Bioflow and Ranger Pro) considered safe by regulatory agencies, adverse effects were seen in the offspring. All three compounds tested altered behavioural reactivity and open field exploration consistent with increased anxiety in a dose-response fashion, though the Roundup Bioflow and/or Ranger Pro formulations caused greater anxiety-like behaviours than glyphosate alone. When sex-based differences were present, males were more affected than females. High anxiety and atypical reactivity to unfamiliar environments are common features observed in people with Autism Spectrum Disorder (ASD).

Glyphosate, common pesticides damage human DNA at low doses
Several common pesticides, including the herbicide glyphosate, cause genetic damage to people’s cells at very low exposure levels, according to a new study. Such damage, often referred to as “genotoxicity”, is linked to cancer. The findings suggest that current pesticide testing and regulation are not fully capturing how pesticides may harm people. The new study tested 10 pesticides that people are exposed to and found that eight damaged or altered the DNA in human cells. For the weedkiller glyphosate, the researchers saw cell damage at the lowest levels tested, suggesting that there is no established safe level of human exposure. It was the first time several of the pesticides were tested for impacts on DNA and the first study to confirm certain mixtures of the pesticides were toxic to cells as well. A mixture of glyphosate, the insecticide acetamiprid and the fungicide fluopyram, for example, damaged cells at the lowest dose tested. The study is here.

Roundup may affect hormones tied to pregnancy and foetal development, new research finds
Exposure to glyphosate herbicide was linked to changes in several hormones that support pregnancy and foetal development in one of the few studies to examine how a widely used herbicide may affect the body during pregnancy. The results come from a new study led by University of Michigan School of Public Health researchers. The study looked at 752 pregnant women in Puerto Rico. The research team found that higher levels of glyphosate and a related compound were associated with changes in hormones that help support the placenta, foetal growth, and timing of labour. The authors write: “This study provides first evidence of associations between prenatal glyphosate and AMPA [the main breakdown product of glyphosate] exposure and disruption of multiple maternal hormonal pathways during pregnancy. Findings suggest these contaminants may interfere with estrogenic, thyroid, and stress hormone systems critical for pregnancy maintenance and foetal development, with implications for understanding mechanisms underlying adverse birth outcomes.”

Exposure to glyphosate weedkiller during pregnancy may increase risk of preterm birth
Exposure to glyphosate herbicide during the middle months of pregnancy may increase the chance of giving birth too early, before 37 weeks, a new study shows. The investigation focused on glyphosate, the active chemical ingredient in Roundup products, which are sprayed on commercial food crops, like grains and legumes [GMW: notably on GM glyphosate-tolerant crops], and on residential gardens. Residues of the chemical have been detected in cereals, snack foods, and fresh fruits and vegetables. The new study, which included 1,450 women, revealed that those with higher levels of glyphosate in urine samples collected during mid-pregnancy were more likely to go into spontaneous labour before 37 weeks than those with lower amounts of the herbicide. The study is here.

Prolonged photosensitivity following exposure to glyphosate herbicide
Photosensitivity is an extreme or abnormal skin reaction to sunlight or artificial light – and it’s a growing problem. It results in symptoms like painful rashes, severe sunburns, blisters, or hives shortly after exposure. While certain medications can cause it, so can exposure to glyphosate herbicides, according to a recent scientific paper. The paper, authored by researchers in the UK, describes a case of severe prolonged photosensitivity to sunlight in a father and daughter shortly after exposure to a glyphosate‐based herbicide from being downwind of a council worker spraying glyphosate.

Glyphosate weedkiller driving evolution of superbugs
Scientists have found that glyphosate can encourage the growth and spread of bacteria that are resistant to antibiotics, raising fresh concerns about the unintended consequences of modern farming. The study suggests exposure to glyphosate triggers natural selection among germs, allowing tougher, drug-resistant bacteria to thrive while more vulnerable strains die out. If passed on to humans, either directly to farmers working in fields or through contaminated food and water, drug-resistant bacteria can make common infections more difficult to treat and increase the risk of serious illnesses that cannot easily be treated. “These results suggest that weedkillers – which, unlike antibiotics, are widely applied in agricultural environments – may have the unintended side-effect of selecting for AMR (antimicrobial resistance) among bacterial communities within the soil,” said Dr Daniela Centrón, one of the authors of the study. More here.

Sublethal glyphosate exposure reduces foraging and disrupts brains of honeybees
Glyphosate was long thought to be safe for honeybees because they lack the enzyme the chemical targets in weeds. However, research shows glyphosate-exposed bees forage 13 percent less after only three days and show changes in brain chemicals linked to behaviour. Across a whole hive, that decline could reduce honey production, weaken pollination, and threaten long-term survival.

GLYPHOSATE, FORESTS AND FIRE

Bombarding America’s forests with Roundup
A year-long investigation by Mother Jones, which has prompted questions from lawmakers in Congress, found that logging companies and the US Forest Service have been spraying massive amounts of glyphosate herbicide in clear-cut and fire-ravaged forests of California. A once-idyllic landscape in remote Northeast California, spanning tens of thousands of acres, is among California’s most heavily sprayed forest areas. Thanks to the chemicals, it is now a moonscape. And even where the Forest Service is claiming not to currently be spraying Roundup, there is evidence that it is.

Watch: Bombarding America’s forests
Mother Jones has produced a series of videos about the issues raised by their in-depth investigation into glyphosate spraying in national forests:
The secret plan to cover the world in herbicide
Surveying California’s Roundup-sprayed forest from above
Checking out what the Forest Service are really doing
Spraying Roundup near Lake Tahoe? A gold medallist is fighting back
US lawmakers demand answers about spraying Roundup all over public lands

Forest Service relies on 15-year-old risk assessment that heavily cites junk science
The US Forest Service’s 2011 risk assessment, which depicts glyphosate as posing no significant threat to people and the environment, references a reassuring review published by Williams et al 27 times – more than any other peer-reviewed paper, to refute studies that raised health concerns. But five of the seven most-cited journal articles in Williams et al were either directly orchestrated by Monsanto or written by authors with financial ties to the company. And the paper itself was recently retracted due to such conflicts of interest (for more on this see our FRAUDULENT BASIS OF GLYPHOSATE REGULATION section). Yet the Forest Service’s risk assessment, basing itself on the now-retracted paper, even claims if you were fully immersed in undiluted glyphosate, there would be no cancer risk.

Listen: Poisoning the forest for the trees
Nate Halverson reports on his year-long investigation into how Roundup is being sprayed in record amounts in California’s forests and the secret plan that helped make it possible. “The wedding of the chemical industry and the Forest Service has got to be seriously and deeply looked at,” Craig Thomas, a fire restoration expert, tells him. The Forest Service is “addicted to herbicide use and glyphosate, and we need to get them into rehab”.

US Take Action: Tell the US Forest Service to stop spraying glyphosate in national forests
Glyphosate can kill plants that provide food and shelter for wildlife, alter forest ecosystems, and expose wildlife and humans to this controversial herbicide. Sign the Environment America petition to tell the US Forest Service to stop spraying glyphosate in national forests.

Groups urge Newsom to stop glyphosate use in California’s forests
A coalition of Northern California residents, advocates, grassroots organisations and professors is demanding that Gov. Gavin Newsom halt the spraying of the herbicide glyphosate in California’s private and state forests, citing concerns about potential health and environmental risks, as well as the now retracted safety study by Williams et al (see FRAUDULENT BASIS OF GLYPHOSATE REGULATION, above).

Why is the US Government dumping toxic chemicals onto public lands?
It’s not just national forests that are being bombarded with glyphosate and a whole series of other toxic chemicals. Over the past year, federal agencies have sprayed tens of thousands of gallons of herbicides and insecticides across the mountains, canyons, plateaus, and deserts of the American West. These spraying programmes are creating “virtual dead zones” in wild places, with a dearth of insect life even in the places where plants survive.

Canada: New research finds aspen trees can act as a wildfire barrier – but they ’re being eradicated with glyphosate

Ontario continues to experience its worst fire season on record. But every summer, forestry companies spray thousands of hectares of Crown land with herbicides designed to kill broadleaf vegetation which competes with coniferous trees that are harvested for their lumber. The most commonly used herbicide for this purpose is glyphosate. Now new research confirms that the very broadleaf trees (aspen) that companies have been busy eradicating in Canadian forests with glyphosate are the firebreaks. “If you significantly reduce aspen in commercial forests, whether it's through brushing or glyphosate, then I really believe that you’re increasing fire risk in the long term,” said Flavie Pelletier, lead author of the new study.

Canadian Forest Service also relies on retracted safety review
The Canadian Forest Service (CFS) also relies on the ghostwritten Williams et al review (see FRAUDULENT BASIS OF GLYPHOSATE REGULATION, above) in dismissing concerns about glyphosate causing cancer or being an endocrine disruptor. And having referenced the now-discredited paper, CFS states, “Such reviews conducted by highly qualified professional toxicologists and risk assessment specialists provide the most credible and reliable sources of information”.

Canada: Debate over forest management rages amid wildfire surge
As of mid-July, the Canadian Interagency Forest Fire Centre had reported 891 active wildfires across Canada. Questions are emerging about how best to manage them. According to the Canadian Forest Service, aerial application of herbicides – mostly glyphosate – is used to suppress competing vegetation helping newly planted conifers such as pine and spruce establish. Forest entomologist Paul Bell says as broadleaf vegetation declines due to glyphosate use, forests can become less diverse, weakening the complex food webs that support healthy ecosystems. For instance, glyphosate removes vegetation that provides food, shelter and breeding habitat. On top of that, environmental scientist Brenna Lattimore says glyphosate also “leaves behind dead, dry vegetation. It’s ready to ignite.” And the broadleaf trees glyphosate kills are “wet trees” with more moisture in them than conifers. “They create natural firebreaks” (see item above for research supporing this, and this in-depth article for more on how glyphosate undermines fire mitigation).

Forest fires and glyphosate: An examination of the unspoken
What happens when millions of hectares of Canadian glyphosate-sprayed forest burn, and the smoke crosses a continent? No regulator in North America has ever asked that question. Not because it’s unanswerable, but because nobody has been required to. Dr Michelle Perro looks at the evidence and makes suggestions for what families can to do to take action and reduce their exposure to forest fire smoke particulates and whatever is riding on them.

Ignoring the evidence: Glyphosate, deer and the abuse of power
Rod Cumberland – the Canadian biologist fired after opposing glyphosate use in forestry because of its catastrophic effect on wildlife – has a book out: “Part memoir, part exposé... about how power and politics and corrupted science endanger our natural world”. And it’s not just available in Canada. Here’s a video of Rod talking to Southwest Magazine about his book and the devastating impacts of glyphosate spraying on deer populations and forest ecosystems that he discovered while working as New Brunswick’s deer biologist.

Canada: Treaty chiefs call for moratorium on aerial glyphosate use across their territory
Leaders representing the 21 First Nations of the Robinson Huron Treaty of 1850 have warned that forestry companies do not have permission to conduct aerial or ground-based herbicide spraying within their treaty territory. The leaders say jurisdiction over the lands and forests remains with the treaty nations. In May 2025 the Chiefs of the Robinson Huron Treaty unanimously passed a resolution calling for an immediate moratorium on the aerial spraying of glyphosate and other herbicides throughout the Treaty territory. The Treaty is an agreement signed in 1850 between the Ojibwa chiefs of Lake Huron and the British Crown.

Images of Roundup and the forest fire are from Shutterstock (licensed purchases). The image of Prof Antoniou is courtesy of himself and the image of Dr Rupy Aujla is taken from his video.

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Review 604: Glyphosate, Fire and Science