Thirty-five million tons of plastic waste have been dumped into the world’s oceans since negotiations on the United Nations plastics treaty began in Uruguay two years ago.

When delegates gather for the final session of UN Environment Programme (UNEP) led talks in Geneva in August, known as INC-5.2, around 1.2 billion tons of unrecycled plastic waste will have been produced since negotiators from 175 nations first put pen to paper.

With plastic production set to rise 40% in the next decade, tens of billions of tonnes of large, small and microscopic chemical particles will scatter throughout rivers, landfills, streams and coastlines, be burned into the air, or discarded in oceans around the world. 

All of them pose a direct threat to human health and the environment.

Ana Paula Souza discovered this firsthand when she participated in a scientific study last year. Despite living what she calls “a very ordinary life” in Geneva far from recycling plants or petrochemical facilities, tests revealed she had been exposed to more than 30 toxic chemicals that leach from plastics—compounds that can disrupt hormones, damage the nervous system, and weaken immunity.

“We live in a world where, just by walking on the street, you’re already being exposed to plastics,” Souza, who works on environment and climate change issues for the UN’s human rights office, told a gathering at the Geneva Graduate Institute on Wednesday, ahead of the upcoming treaty talks. “I’ve been exposed, and you too, without our consent.”

The upcoming Geneva talks may be negotiators’ final chance to achieve what UNEP and environmental groups call “the most important multilateral treaty” since the 2015 Paris climate agreement.

The negotiations pit over 100 nations advocating for caps on plastic production and chemical regulation against petrochemical giants including Saudi Arabia, the United States, Russia, and China—countries that view plastics as a crucial revenue stream as renewable energy threatens fossil fuel demand.

With all 175 countries required to agree by consensus, and talks having already failed in Busan, South Korea, in November, the path forward remains uncertain.

“There is little assurance that the next INC will succeed where INC-5 did not,” the Global Alliance for Incinerator Alternatives said after the Busan talks collapsed. “There is a strong probability that the same petro-state minority will continue their obstructionist tactics and further imperil the plastics treaty process.”

For health researchers, mounting evidence of the plastic threat is becoming impossible to ignore.

Planetary experiment with unknown consequences

The convenience, cost, durability and usefulness of plastics in industries from fashion to food, medicine, construction and healthcare has led to a societal addiction that has become a planetary-scale human health experiment. Despite their lightweight design, humanity has produced 8.3 billion metric tons of plastic—with 6.3 billion metric tons discarded as waste.

Plastics have grown immensely in chemical complexity since their invention, evolving from simple fossil fuel derivatives into materials containing thousands of synthetic compounds. They now surround us—in our food, air, water, and rain. Yet we remain largely unaware of the potentially toxic effects of thousands of these chemicals now ubiquitous in modern everyday life.

Researchers have identified over 16,000 chemicals used in plastic production, with at least 4,200 considered “highly hazardous” to human health and the environment, according to a landmark report published last year by scientists at the Norwegian University of Science and Technology (NUST).

Around 5,000 of the compounds in plastic are total unknowns—scientists have not sufficiently studied them to understand their toxicity, leaving potential health effects up in the air.

The 16,000 are also just those scientists have been able to identify—the report’s authors admit there are likely many more compounds out there they haven’t caught yet. Only 980 hazardous chemicals— 6% —are currently regulated by international treaties.

“Chemicals present in plastic products cause hazards such as cancers, genetic mutations, and harm to the reproductive system,” said Albert Magalang, a Philippine environment and climate change specialist who is a member of his country’s national delegation to the treaty talks. “I know for a fact that the health sector is aware that about 10,000 chemicals are used in plastics [for which] they don’t have any hazard data.”

Science and regulation can’t keep pace

The regulatory challenge is compounded by industry practices. When authorities restrict or ban chemicals, manufacturers often replace them with structurally similar substitutes that carry the “same or other unknown hazards,” according to the Plastics Health Map, an open-source database mapping research on plastic chemical exposures.

The pace of scientific evaluation adds another layer of delay. Studies on the health impacts of substitute chemicals typically commence years after their introduction to the market, creating a perpetual knowledge gap. As plastic chemicals proliferate faster than research can evaluate them, both regulatory systems and scientific understanding struggle to keep pace with determining their health effects.

This regulatory gap reflects a deeper problem: the vast majority of plastic chemicals lack basic safety information. Researchers don’t know their identities and structure 25% of the time, their functions 50% of the time, whether they’re present in plastic 56% of the time, and their hazards 66% of the time, the NUST report found.

“We face a major challenge in the lack of transparency across the plastics value chain,” said Andrea Zbinden, senior policy advisor for the Swiss Plastics Treaty delegation, which will host the talks in August. “I want to know, actually, what is in the plastic product that I’m using every day.”

Despite this knowledge gap—likely to persist for decades as new chemical compounds continue to multiply—leading health experts believe human health must be central to negotiations on the plastics treaty, which will be legally binding but requires consensus to pass.

“Human health must be central to the plastic treaty,” said Dr Maria Neira, WHO’s environment lead. “Plastics pose risks to human health, and the risks are happening across the entire life cycle, from production to destruction and then use and disposal.”

The push for binding global action

The demand for transparency is driving Zbinden and a group of 94 countries to push for a global list of banned chemicals and plastic products—something that has proved contentious in negotiations. Given how quickly manufacturers replace regulated chemicals with similar compounds, Zbinden insists the list must be regularly updated to reflect the latest science.

“The treaty must also include a mechanism to regularly update the list based on the latest science and development,” Zbinden said. “While every effort should be made to reach consensus, it is important to establish a clear procedure for decision making to ensure the list can be updated effectively.”

Major plastic producers have strongly opposed including such measures. During negotiations in Busan, references to “chemicals of concern included in plastic products” were dropped from the Chair’s Text, raising concerns that obstruction from industry may force countries supporting the strongest health measures to pursue separate commitments outside the treaty framework if consensus fails again.

The most ambitious coalition of nations is pushing for sweeping changes that extend far beyond chemical bans. In a position paper released after the failed Busan negotiations, the 70 countries comprising the High Ambition Coalition reaffirmed their “common ambition of ending plastic pollution by 2040” and emphasized that “effective and common legally-binding global rules are essential.”

They want binding transparency and reporting requirements on plastic polymer production and chemical composition, time-bound targets to reduce production and consumption of primary plastic polymers to sustainable levels, as well as enforcement of the principle that “polluters should be held responsible for their activities and products.”

The coalition’s concerns extend to another health threat: microplastics—particles so small they can cross into organs and the bloodstream.

Research in this emerging field has revealed that microplastics can alter cellular behaviour in internal organs, with scientists identifying a new condition called “plasticosis” in studies of birds. Humans now consume approximately five grams of these particles weekly through normal eating, drinking and breathing, yet their long-term health impacts remain largely unknown.

“We call on all INC members to seize this historic opportunity to conclude an ambitious and effective treaty that demonstrates our collective resolve to end plastic pollution for the benefit of current and future generations,” the coalition stated. “We encourage everyone to continue their efforts, hold governments to account.”

Economic case for action

The coalition’s sweeping demands are backed by mounting evidence that inaction carries enormous economic costs in health damages.

Plastic pollution isn’t cheap, especially for health systems. A study published last year by the Endocrine Society found that chemicals used in plastics generate over $250 billion in annual health costs in the United States alone.

In the European Union, researchers estimate exposure to hormone-disrupting chemicals costs over €150 billion annually in health care expenses and lost earning potential. These endocrine-disrupting chemicals are present in everyday products and pesticides, but industry lobbying has delayed EU action to identify and restrict their use.

With microplastics now found in human blood and plastic production showing no signs of slowing down, UNEP has warned that the economic costs of inaction on the chemical and plastic pollution crisis could reach 10% of global GDP.

Image Credits: Naja Bertolt Jensen, Muhammad Numan, Fiqri Aziz Octavian, Antoine Giret.