26% of the chemicals that are in plastics are dangerous to health, and another 66% we do not know

Barcelona"I am not in favor of recycling, because there are many chemical substances in plastics and many that we still do not know are there or how they act." This is how forcefully scientist Laura Monclús, from the Norwegian Geotechnical Institute (NGI), expressed herself this Monday in Barcelona. This toxicology expert has stated that increasing the percentage of recycled plastic will not solve the plastic crisis, but rather what is needed is to rethink the "essentiality" of plastic products: "If there is any product that is essential to be made of plastic, which there are, it will be necessary to ensure that they are completely safe (for health), but the majority of the plastics we consume are not essential," warned Monclús, during a conference on the Global Plastics Treaty organized by the Waste Agency of Catalonia.

"There is still a lot of work to be done before we can have safe plastic recycling: bisphenol A, for example (which has been confirmed to be an endocrine disruptor), is present in all food cans," she added. Monclús is part of the Scientific Coalition, a group of scientists that advises UN governments on the development of this international treaty that aims to put an end to global plastic pollution. The negotiation, however, has been blocked for months by oil-producing countries (and, therefore, plastic-producing countries), which refuse to include measures to limit production and want the text to focus on waste management.

Within the framework of her work to provide a scientific basis for the treaty, Laura Monclús has co-led the most exhaustive scientific study conducted to date on the chemical substances associated with plastics, which was published in the journal Nature in 2025. According to that study, plastic products contain up to 16,000 associated chemical substances and, of these, it is already known that at least 26% are harmful to health. The problem is that there is another 66% for which there is not enough information to calculate their danger and which, therefore, "could also be harmful, but it is simply not known," the scientist alerts. All these substances are found in all polymers, from PET or other types of polyethylene to PP (polypropylene) or PVC (polyvinyl chloride): there is no type of plastic that escapes them.

Scientists demand more transparency from the industry

Monclús has insisted on warning about the great lack of scientific information regarding these products and has requested that the treaty also provide "more transparency from the industry". The Scientific Coalition, in fact, demands that the treaty include the obligation to report on all chemical substances present in plastics and their degree of danger to human health. They also call for a regulation of these substances and a simplification of plastics to make them safer and more sustainable, since today "they are terribly complex materials".

During the conference, the stalemate in which the negotiations for this treaty currently find themselves was also highlighted. Among many large and small disagreements, there is a fundamental division. On one hand, there is the so-called High Ambition Coalition, a group of countries led by the European Union, Canada, Australia, Japan, and the Pacific states, which demand a binding and ambitious treaty that imposes measures throughout the entire plastic production chain and includes even limits on the manufacture of new plastics, in addition to the obligation to report all chemical substances they contain. At the other extreme is the one known as Like-minded group (which would be translated as the like-minded group or the group with common interests), in which the United States, Russia, China, Saudi Arabia, Qatar, or India stand out. These are countries that, despite often being political rivals, ally themselves in this forum for a common interest: oil.

"China is beginning to change its position, because it has realized the economic benefits that this can represent," explained lawyer Hélionor de Anzizu, from the Center for International Environmental Law (CIEL), who is participating as an observer in these negotiations. Beijing, she says, has shown interest in developing some of the "technologies that extract plastic from the oceans" and could see it as a business opportunity. A good part of this plastic dumped into the sea comes from an international traffic of plastic waste that already led the Beijing government, in 2018, to ban the import of plastic waste into the country, saturated by the tons of useless trash that was arriving. At the same time, Xi Jinping could be assessing the opportunity to position himself in the market for alternative technologies to plastic as he has done in the renewable energy market, where he is at the forefront of the world, notes the expert.

However, De Anzizu admits that it is unlikely that the treaty will be unblocked soon. Despite positive steps by China, the United States, which were no longer particularly ambitious during Joe Biden's era, "have adopted a very tough position since the beginning of Donald Trump's mandate" and even threatened some countries with tariffs due to their position in these plastics negotiations, he explains.

This very week, government delegations are meeting in Thailand to advance the talks and be able to bring a new draft text to the formal negotiation next March, but De Anzizu does not believe the Treaty will be mature enough by then, especially considering that it must be approved by consensus (without opposition from anyone) and this is really complicated in the current geopolitical context.

The only good news is that "since the start of the negotiations, there has been a boom in national regulation" regarding plastic consumption, according to De Anzizu. What the UN is failing to do, state governments and also local and regional ones will have to do, which are often the ones that implement plastic regulations and manage waste. Precisely, Catalonia participates in a coalition of local and regional governments that already has 111 signatories and acts as an observer in the Treaty negotiations, pushing for an ambitious agreement. "We have managed to include in the treaty two articles that mention the importance of local and regional governments both in the management of plastic waste and in the dissemination and communication to the citizenry," also explained Ignasi Mateo, from the Waste Agency of Catalonia.