Glyphosate: a necessary evil?

My public endorsement of glyphosate authorization in the EU (https://www.nature.com/articles/d41586-023-03589-z) has caused confusions about the implications of my scientific studies on glyphosate.

While researching glyphosate, I worked at the University of Caen with Professor Gilles-Eric Séralini and later at King's College London with Professor Michael Antoniou. Our focus was on finding gaps in the assessment of pesticide toxicity. We discovered health effects from glyphosate exposure and shortcomings in health risk evaluations. This might seem conflicting with supporting glyphosate authorization, but I'll explain the main reasons for this perspective below.

Deciding whether a pesticide should be authorised is a multi step process. This involved hazard assessment (whether it is toxic), risk assessment (whether this toxicity poses a risk), and risk management (whether this risk is acceptable or not in light of the importance for a sector and the existence of alternatives).?

What are the toxic effects of glyphosate??

Most of my studies suggested that glyphosate is more toxic than originally thought. Current studies show that glyphosate can cause a large range of adverse outcomes, which are mostly found in studies on laboratory animals exposed to glyphosate doses in the range of the milligram per kilo of body weight. This includes toxic effects to liver and kidneys, neurotoxic effects, carcinogenic effects or even effects on reproduction and development. The most recent and perhaps most impactful example is the recent report from the Global Glyphosate Study of the development of leukaemia in rats exposed long-term from prenatal life to glyphosate and glyphosate-based herbicides (https://www.biorxiv.org/content/10.1101/2023.11.14.566013v1). Whether toxic effects from glyphosate exposure can be found at lower doses, typically below the milligram per kilo of body weight, is still a matter of debate.

We also understood why toxic effects remained undetected in the regulatory risk assessment. Glyphosate was inappropriately tested due to shortcomings in?study design, data, and methodologies (https://ehjournal.biomedcentral.com/articles/10.1186/s12940-021-00773-4). This was the case for long-term effects of prenatal exposure or/and effects on the gut microbiome (https://www.frontiersin.org/articles/10.3389/fmicb.2022.888853/full).?

Glyphosate is not the only problem with Roundup

Glyphosate was consistently less toxic than its commercial formulations (https://www.sciencedirect.com/science/article/pii/S0278691519301814?via%3Dihub). This is another important topic of confusion. Agricultural workers are never using glyphosate alone. There is a general agreement that commercial formulations are more toxic than glyphosate alone, but these formulations are still poorly regulated. This means effects on glyphosate applicators cannot all be predicted by regulatory tests.?I have always argued for more regulation of these pesticide formulations. Some progress were made with the ban of toxic surfactants, and the creation of regulations for more transparency. There is still a lot to be done. However, the regulation of active ingredients is fundamentally different to that of formulations. Mixing both glyphosate and its formulations in regulatory recommendations would be contradictory to the differences that I always tried to highlight.

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Can the identified toxic effects pose risks which are unmanageable?

To assess the risks of harm from either glyphosate or its coformulants, we need to look at how much farmers or the public are exposed to. However, we have gaps in our knowledge because we don't have a complete understanding of glyphosate exposure in all groups of people. Nonetheless, it's highly unlikely that glyphosate has negative effects on the general population because any harmful effects found in scientific studies occurred at doses much higher than what people normally encounter. The levels of glyphosate in the urine of the general population are typically way below the amounts that could cause harm, around a thousand times lower than the doses that showed toxic effects in lab animals. (Figure 6.3. in https://shop.elsevier.com/books/herbicides/mesnage/978-0-12-823674-1. ?

Agricultural workers deserve special attention in this matter. Some believed that Glyphosate formulations were very safe, leading many to skip safety measures when spraying them. This caused numerous cases of immediate poisoning, mainly due to highly toxic surfactants like POEA. Additionally, it's possible that workers who were exposed to high doses of glyphosate without precautions may have developed cancer.

So does it mean glyphosate should be banned??

Farm workers need protection, not just from harmful pesticides, but also from the socio-economic impacts of commercial agriculture. While glyphosate, a key herbicide, is toxic and its full consequences aren't entirely understood, it plays a crucial role in agriculture, making it a necessary but potentially harmful tool.

Banning glyphosate may not lead to more sustainable practices; instead, it might result in the adoption of other pesticides, potentially more toxic and less understood. Moreover, it could increase the costs of food production since glyphosate is a cost-effective and efficient weed control method. Estimating the costs of a ban is challenging due to varied and uncertain effects, but it's certain that some sectors would face economic losses (https://www.nature.com/articles/s43247-023-00951-x). The ramifications extend beyond agriculture, as demonstrated by a French government report in 2021, which found that replacing glyphosate with alternative chemicals for weed control on railways would be significantly more expensive, less efficient, and potentially more toxic (Report CGEDD / CGAAER N°012708-01).

What can we do to move forward ?

II think we can make glyphosate safer by adding an extra safety margin to its recommended daily intake, considering uncertainties about its health effects. We should also limit its use to essential farming needs, like avoiding preharvest desiccation, and prevent private users without enough knowledge from using it. Some countries are already taking such steps, which makes me optimistic about safer glyphosate use.

Additionally, we need to address conflicts of interest in the regulatory process. The decisions about glyphosate are not just based on objective facts; human judgment plays a role. Biases like confirmation bias, where people favor information supporting their beliefs, can affect these judgments. Glyphosate has become a symbol of industrial agriculture, and political and financial interests sometimes overshadow scientific considerations.

Conclusion. Why I welcome the Commission’s decision to continue to allow the use of glyphosate

I aligned my recent stances with my scientific principles. The prevalent use of chemicals for weed control in intensive farming isn't really sustainable. We should shift to more sustainable methods, but it's a big task that can't happen overnight. Completely banning glyphosate might not be fair; we should explore ways to benefit from its advantages while addressing its drawbacks.

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