Glyphosate: toxicity and exposure risks

The fierce controversy surrounding glyphosate, sparked in recent years by insinuating journalists, a few militant scientists, and NGOs, has had numerous negative effects and led to abuses that prevent the general public from distinguishing truth from falsehood. The confusion between danger and exposure levels is perpetuated either through ignorance on the part of the authors or deliberately to create a climate of fear. It should also be noted that the teaching of food toxicology is limited in many scientific training programs, including medical universities, which explains why some scientists are unable to distinguish between danger and risk.

Should the precautionary principle be applied to glyphosate?

This is a question that comes up often. We know the simplistic slogan: when a danger is suspected, “when in doubt, ban it.” But why target only glyphosate? Why not ban coffee and all the other substances classified as probable carcinogens by the IARC? Either the risk of cancer is proven under real-world conditions of use of a substance, in which case binding measures must be taken to reduce this risk, or the risk is not seriously established. Otherwise, anyone can invoke the precautionary principle to ban any substance.

It is worth remembering that glyphosate is the subject of a consensus among all health agencies. Climate change is the subject of a consensus, as is the benefit of vaccines, and tobacco is classified as a known carcinogen, but not coffee,nor talcum powder when used to protect babies’ bottoms. Why make an exception for glyphosate? Is fear fueled by a vocal handful of activist scientists more credible than scientific studies that have reached an international consensus?

Studies far removed from the real-world conditions of glyphosate use

Critics of glyphosate are on the lookout for any unfavorable scientific publications. Glyphosate could have an impact on the nervous system, causing memory disorders or depressive syndromes, or could alter gene expression, microbiota development, apoptosis of abnormal cells, etc. (The numerous favorable studies, more than 1,500 over the last decade, are ignored by glyphosate critics). But all these unfavorable studies often suffer from the same flaws: methodological biases, lack of rigor, and failure to translate negative effects into real-life exposure situations in humans.

Lobbying and conflicts of interest in the anti-glyphosate movement

Some studies are sponsored by organizations and companies known for their anti-glyphosate activism; lobbying and conflicts of interest are not always the fault of Monsanto-Bayer.

This is the case of a well-known critic of glyphosate, Christopher Portier, former director of US federal research institutions and recruited by a predatory law firm. He sent letters to European and US health authorities expressing his doubts about the assessment of glyphosate. In an article in the AFIS magazine “Science et Speudo-sciences” dated June 4, 2018, it is stated that C. Portier is “a long-time employee of the Environment Defense Fund, an American environmental NGO that has been campaigning against pesticides since the 1960s. In May 2017, Mr. Portier had been paid for at least two years by an American law firm to prepare a class action lawsuit against Monsanto over glyphosate. Documents declassified by the US courts at the end of 2017 (2) show that Christopher Portier received approximately $160,000 in fees over two years (excluding expenses) to collect scientific information on the dangers of glyphosate that could be used against Monsanto.”

Here are a few examples of media campaigns aimed at discrediting glyphosate that have made headlines in the media, on TV channels, and on social networks:

Three questionable studies on glyphosate rejected by the scientific community

• In December 2008, a study from the University of Caen, published in the journal Chemical Research in Toxicology, attempted to highlight the impact of various glyphosate-containing formulations on human cell lines. The authors reported various cell damages (necrosis, asphyxia, DNA degradation, etc.) allegedly induced by glyphosate, its degradation product (AMPA), or an adjuvant present in some preparations. This study was heavily criticized by the scientific community. The French Agency for Food, Environmental and Occupational Health & Safety (ANSES, formerly AFSSA) highlighted three methodological errors:

• In 2010, Argentinian scientists attempted to assess the effects of low doses of glyphosate on development by studying vertebrate embryos. Their study, published in the journal Chemical Research Toxicology on August 9, 2010 (1), notably states that the treated embryos are highly abnormal. This is also a questionable experiment, as the solution used contained a concentration of 72 to 192 mg of glyphosate per liter, which is 720,000 to 1,900,000 times higher than the maximum permitted dose for drinking water in France.
• One of the most controversial and widely publicized studies against glyphosate was conducted in 2012 by molecular biology professor Gilles-Éric Séralini on the toxicity of Roundup and Monsanto’s NK603 GM corn. This researcher, a co-founder of GRIIGEN, which opposes the cultivation of genetically modified plants, received support from Elise Lucet in a report by Envoyé Spécial and Le Nouvel Observateur on September 20, 2012, which published an article entitled: “YES, GMOs ARE POISON.” However, Gilles-Éric Séralini’s study was met with almost unanimous criticism from the scientific community before being invalidated by three large-scale European studies. The study was retracted from the prestigious journal Food and Chemical Toxicology, which had initially published it (it was republished in June 2014 in open access in the German journal Environmental Sciences).

Glyphosate pissers to the rescue

More studies tainted by undeclared conflicts of interest

The Italian Ramazzini Institute, known for its partisan stance against pesticides, published a study in its journal in the summer of 2025 claiming to provide significant evidence of a dose-related increase in benign and malignant tumors in rats exposed to glyphosate. This study was promoted by a wide range of NGOs, activists, and sensationalist journalists, political organizations, and interest groups in the US litigation sector. This study aimed to contribute significantly to the debate surrounding the health effects of glyphosate, but the scientific weaknesses of this publication did not attract much attention from the newspaper L’Humanité, Europe Ecology, Le Monde, local newspapers such as Ouest-France, and others. The study was critically analyzed by the renowned biostatistician Robert Tarone in “The Firebreak,” a summary of which follows:

• The results provided by Ramazzini’s researchers suffered from flawed statistical analysis (using incorrect approximate p-values rather than much higher exact p-values), meaning that the number of significant tumor trends was actually very small.
• The funding for the research was tainted by undeclared conflicts of interest (particularly from the American litigation sector)
• The article’s publication process was biased (in a journal controlled by Ramazzini and reviewed by an activist from the Pesticide Action Network).
• The researchers drew conclusions despite the lack of statistically significant evidence in their results tables.
• The researchers chose not to cite or discuss an important study on tumors in rodents that contradicts their findings.
• The summarized results of IARC monograph 112 concerned only observed adenomas, with no apparent progression to carcinomas.
• The three groups exposed to glyphosate in the Ramazzini study all showed no evidence of a trend in tumor incidence across all anatomical sites.

A translation of the article containing more details on this critical analysis is available by clicking here

The background to the retraction of an article 25 years after its publication

More recently, an article published in 2000 by Williams et al. on the safety of glyphosate in the peer-reviewed journal *Regulatory Toxicology and Pharmacology* was retracted on grounds of scientific integrity, 25 years after its publication. This retraction, predictably, triggered a media campaign by anti-glyphosate groups, amplified in the local press and on social media. This article, accepted in 2000 by health agencies, presented evidence of glyphosate’s safety and relied on data provided by the industry. Furthermore, a letter leaked during the preparation of legal proceedings against Monsanto allegedly revealed that the company had participated in writing the article.

The retraction of the article is therefore not based on manipulated data or flawed methodology. The EFSA had already reacted two years ago to this article and the evidence presented, stating that industry involvement had been declared and that the way the article was written did not compromise its scientific content. It is interesting to note that the co-editor of the journal that retracted the article (Mr. Martin van den Berg) is known for his activism against industry and gained notoriety in the early 2000s for his rudimentary blood tests to support NGO campaigns against brominated flame retardants. Further details on this case, which contain other interesting information on the reasons for this retraction, are available by clicking here.

Glyphosate and conservation agriculture

Studies have shown that glyphosate is also an antibiotic and that it degrades the soil microbiome. It can chelate calcium and magnesium, reducing their absorption by plants. These concerns have never been confirmed in soil conservation techniques (particularly no-till farming) where glyphosate is used to destroy cover crops. In fact, the opposite is true: the objective of these farming techniques, widely used especially in the USA, is to restore soil biodiversity. Again, these studies have nothing to do with the reality of agricultural practices and the consequences related to the doses used. It is difficult to imagine how such a priority as restoring soil biodiversity could be thwarted by the application of a toxic substance that would poison the microflora.

In addition, conservation agriculture practices (reduced tillage, direct seeding, etc.) with the use of glyphosate produce a significant reduction in CO2 emissions of around 54.94 billion kg, equivalent to taking 21.8 million cars off the road each year (12).

Dallas dethroned by glyphosate; a saga that is far from over

Will the definitive ban on glyphosate in agriculture be enough to eliminate this molecule from the environment and from the urine of voluntary urine donors? This is doubtful, as researchers have found that most of the glyphosate found in European rivers does not come from agriculture, but from wastewater treatment plants, from additives used in laundry detergents: aminopolyphosphonates. The war on glyphosate is therefore far from over, with washing machines and the cleaning ladies who use them likely to be the next victims..….

Disastrous consequences for everyone

The ban on glyphosate in France compromises the availability of an effective tool for farmers, individuals, and local authorities. The economic consequences are catastrophic, both for farmers who face unfair competition from foreign producers and for local authorities who must resort to weeding, most often by hand, which costs taxpayers a fortune. As for amateur gardeners, they no longer have an effective weeding solution, except for elbow grease, as practiced in the Middle Ages. This is a step back more than a century to satisfy an electoral clientele blinded by backward-looking and anti-progressive extremists.

For more information; the glyphosate saga (a library of articles, press releases, etc.); click here