They are three INRAE researchers specializing in plastics, with complementary approaches: Xavier Cousin, a physiologist studying their effects on fish; Marie-France Dignac, a geochemist working on microplastics in soils; and Muriel Mercier-Bonin, a toxicologist specializing in the effects of microplastics on the digestive system. Through their work on plastics and a growing awareness of their harmful effects, a desire to get involved has emerged.
“During the INC-2 (2nd session of the Intergovernmental Negotiating Committee) in Paris, I wasn’t accredited, but I was able to attend the side events,” explains Marie-France Dignac. “That’s when I understood how much weight our research could carry in the debates.” During this period, the three specialists joined the Coalition of Scientists for an Effective Plastics Treaty, an international group created in 2022. Bringing together more than 450 scientists from over 65 countries, this coalition was formed to fill the gap left by the lack of an official scientific body involved in the plastics treaty negotiations, unlike international negotiations on climate or biodiversity.
With the support of INRAE, Xavier Cousin, Marie-France Dignac, and Muriel Mercier-Bonin managed to join the French delegation at the CIN-3 conference, with observer status. This special status allows them access to working groups without officially representing France's position, while maintaining their impartiality. "Joining an NGO was also an option, but that could have compromised the independence and scientific rigor we were determined to preserve in this debate," explains Marie-France Dignac.
This involvement is part of a broader national scientific movement: all three are members of the research group (GDR) "Plastics, Environment, Health," which brings together the French scientific community on these issues. Xavier Cousin sits on the steering committee, while Marie-France Dignac and Muriel Mercier-Bonin serve on the scientific committee.
Direct support for negotiators
In Nairobi (CIN-3), Ottawa (CIN-4), and then Busan (CIN-5.1), the three scientists joined forces with other international researchers (71 in Busan), including a dozen French speakers, forming a cohesive group to directly support the negotiators. Their role was multifaceted: identifying the delegates' needs, responding to urgent requests, and providing the necessary scientific insights. Depending on the situation, this might involve explaining the consequences of a regulatory choice, clarifying often-confused concepts, such as the difference between bioplastic and biodegradable, or correcting scientifically unfounded arguments.
“As active members of the coalition, we are also asked to review or contribute to documents, articles, and proposals,” adds Muriel Mercier-Bonin. “We feel that our work has meaning, that it is part of an ambitious collective effort. It’s demanding, sometimes exhausting, but it also creates very strong cohesion and incredible collective energy.” She observes this same dynamic among younger members: “I am impressed by the commitment and skills of young researchers, both French and international. They contribute enormously to the process, at every stage of the negotiations.”
“Raising awareness is part of our role.”
"If we continue on our current path, soon no one on the planet will be able to enjoy a healthy environment" - Marie-France Dignac
If researchers have managed to find their place among the many actors already involved with delegations, NGOs, industries or lobbies, it is thanks to the scientific independence they embody. Volunteers, without commercial or political interest, they claim a single objective: "to provide the most rigorous and impartial information about the environmental and health risks linked to plastics," summarizes Marie-France Dignac.
“Raising awareness is part of our role as scientists,” insists the INRAE researcher, who is also a member of the steering committee of the Coalition of Scientists. And the situation is urgent: plastics are now accumulating everywhere. In the oceans, the soil, living organisms, even in the most remote environments like the Arctic snows. “If we continue on our current trajectory, soon no one on the planet will be able to enjoy a healthy environment,” warns the soil specialist. This observation is no longer just scientific; it raises a question of environmental justice. The right to a healthy environment, now recognized as a fundamental human right by the UN, could become unenforceable on a global scale.
At CIN-4, scientists noted a real need for scientific or technical guidance among some delegates, who are often mobilized on several fronts – climate, biodiversity, desertification – without always having a team of specific experts on plastics. “Three major points of confusion came up regularly,” observed Xavier Cousin.
- The first point concerns the distinction between biodegradable, bioplastic, and bio-based. “The term bioplastic is often used vaguely, sometimes deliberately to suggest an environmental benefit that isn’t always real.”
- The second point concerns recycling, sometimes perceived as a one-size-fits-all solution: “Very active lobbying presents it as a cure-all, which tends to overestimate its effectiveness in addressing the plastics crisis.”
- The third point of concern is the chemical substances associated with plastics, which can be released into the environment or food throughout the plastics’ entire lifecycle, from production to end-of-life. “Open-air incineration is still practiced in some regions, with particularly harmful effects on health. Our discussions confirm that these risks remain largely unknown,” emphasizes Xavier Cousin.
A leading joint scientific expertise from INRAE and CNRS on plastics used in agriculture and food
Published in May 2025, this collective expert review mobilized 30 European researchers and over 4,500 scientific references to provide a comprehensive overview of the uses, properties, and impacts of plastics throughout their lifecycle. The diagnosis is alarming: plastics are ubiquitous, found even in the air, water, soil, food, and living organisms. In France, agricultural soils appear to be major receptacles of this pollution, particularly due to inputs from urban compost. The report also highlights the risks associated with food-grade plastics, some components of which (such as bisphenols and phthalates) can migrate into food and act as endocrine disruptors once ingested. The report calls for stricter regulation from the design stage of plastics, limitations on their production and use, and a more structured international governance framework.
Combating misinformation
Misinformation proved a real obstacle during the negotiations. "Some claims contradicted everything we know scientifically," laments Muriel Mercier-Bonin, referring to a discussion on the size of microplastics. "Some delegates didn't understand why this topic was being addressed in the treaty, as if plastic pollution were solely a matter of waste management."
“We have witnessed several instances of disinformation,” said Xavier Cousin.
Yet, these particles, invisible to the naked eye, are now present in all environments, and their ability to cross biological barriers and transport toxic chemicals makes them a central issue for human health and the environment, explains the specialist in the effects of micro- and nanoplastics on the digestive system. "There was also, for example, this idea that the toxicity of chemical substances depends on the region," adds Xavier Cousin. "Certainly, temperature or other parameters can influence some effects, but this kind of argument is scientifically unfounded, and we have witnessed several instances of misinformation," the researcher laments.
Two opposing views of the treaty are emerging.
The negotiations are struggling to reach a conclusion and are revealing two opposing visions of the treaty.
- An ambitious approach, supported by a broad coalition of states, NGOs, and scientists. This vision is championed in particular by the High Ambition Coalition to End Plastic Pollution, which brings together 67 countries, including France, Rwanda, Norway, and Canada. The alliance advocates for binding targets for reducing virgin plastic production, strict regulations on chemicals, and science-based governance.
- Some oil and/or plastic-producing countries support a limited version of the treaty, focused on technological solutions, recycling, and waste management. The Coalition of Scientists warns against this restrictive approach: without a drastic reduction in production, downstream technological solutions will remain woefully inadequate to address the crisis.
While their expertise helped to inform the negotiators about the scientific basis of the treaty, the researchers themselves encountered firsthand accounts that enriched their thinking and shifted their scientific perspective. “We were deeply moved by the testimonies of Indigenous peoples and local communities, and, for example, the three of us discovered the role of waste pickers,” explains Muriel Mercier-Bonin. “These populations experience the effects of plastic pollution on a daily basis, in very harsh conditions. Their accounts show that we are not all equally affected by the impacts of this pollution, and these stories change the way we perceive our own scientific work once we are back in the lab.”
Prepare for the next stage of negotiations
As the next round of treaty negotiations (CIN5.2) approaches, scheduled for August 2025, the three INRAE researchers are continuing their awareness-raising work. For the Coalition of Scientists, they coordinated, co-signed, and translated into French several analyses of the treaty text under discussion, focusing on plastic pollution, chemical substances, and health issues.
Requested in France by the ministries involved in the negotiations (Ministry of Ecological Transition and Ministry of Europe and Foreign Affairs) and the diplomatic advisors of the Elysée, they provide scientific data and their expertise to inform regulatory options and consolidate the French position.
These scientific messages were also delivered by Xavier Cousin and Marie-France Dignac at the 3rd United Nations Ocean Conference (UNOC), held in Nice in June 2025. Just weeks before negotiations resumed in Geneva, the summit also marked a political turning point: with the Nice Appeal, France brought together 95 states for "an ambitious treaty on plastics." This served as a reminder that, faced with this global challenge, only international cooperation and rigorous scientific rigor will lead to an agreement commensurate with the scale of the plastic crisis.
https://www.inrae.fr/en/news/global-plastics-treaty-inrae-scientists-engaged-negotiations
