There are more substances of concern in plastic than previously known

More than 350 million tons of plastic are produced worldwide every year. All of these plastics contain a wide variety of chemicals that can be released sooner or later. Some of them are both environmentally harmful and dangerous for humans and animals. However, most of these chemicals have not been fully scientifically studied, nor are consumers aware of them.

Prof. Stefanie Hellweg, Professor of Ecological Systems Design at the ETH Zurich, Switzerland, has now, together with a team, for the first time classified all plastic monomers, additives and processing aids that are approved worldwide for the manufacture of plastics based on usage patterns and risk potential. The scientists came to an unpleasant result.

Great chemical diversity

In total, Hellweg and her colleagues identified around 10,500 different chemicals that are intentionally introduced into plastic. Of these, 2,489 were found in packaging, 2,429 in textiles, 2,109 in products that come into contact with food, 522 in toys and 247 in medical articles (including masks). The researchers rated 2,480 substances or 24 percent of all substances as “potentially of concern”.

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“This means that almost a quarter of all chemicals used in plastic are either highly stable, accumulate in organisms or are toxic. These substances are often toxic to aquatic life, cause cancer or damage certain organs, ”explains Helene Wiesinger, doctoral student at the Chair for Ecological System Design and first author of the study. About half are chemicals that are manufactured in large quantities in the EU or the US, according to the scientists.

“It is particularly noticeable that many of the questionable substances are barely regulated or described ambiguously,” continues Wiesinger. In fact, we’re talking about more than half – 53 percent – of the substances of concern that are not regulated in the US, EU or Japan. Up to 901 of these dangerous substances are officially approved for use in plastics that come into contact with food in these countries. Scientific studies are completely lacking for around ten percent of all potentially questionable substances.

Plastic monomers, additives and processing aids

Plastics consist mainly of organic polymers. In order to give the various types of plastic the desired properties, additives such as antioxidants, plasticizers or flame retardants are added. In addition, processing aids such as catalysts, solvents and other chemicals are used in the production process.

“So far, research, industry and regulators have mainly focused on a limited number of hazardous chemicals known to be found in plastics,” says Wiesinger. For example, she says that plastic packaging as the main source of organic pollutants in food is at the center of the debate. Phthalate plasticizers or brominated flame retardants have been detectable in house dust and indoor air for some time. In previous studies, researchers concluded that far more plastic chemicals in use around the world are potentially dangerous than previously thought.

Nevertheless, the ETH researchers were amazed by the results of their study. “The unexpectedly high number of substances of potential concern is worrying,” says Zhanyun Wang, Senior Scientist in Stefanie Hellweg’s group. Exposure to such substances can adversely affect the health of both consumers and workers and can also damage ecosystems. “In addition, problem chemicals can affect recycling processes and the safety and quality of recycling materials,” emphasize the researchers. And that’s not all, they add. More plastic chemicals could be problematic, Wang fears. “Recorded hazard data is often limited and dispersed. For 4,100 or 39 percent of all substances we identified, we were unable to categorize them due to a lack of hazard classifications. “

Too little data, too little transparency

The researchers see a lack of transparency for chemicals in plastics and “scattered data silos” as the biggest problem. For their study, they viewed more than 190 publicly accessible directories and data sources from research, industry and authorities over a period of more than two and a half years. Of these, only 60 registers contained sufficient information on additives in plastics. “We found several critical knowledge and data gaps, particularly for the substances and their actual uses. This ultimately hinders consumer choice for safe plastic products, ”comment Wiesinger and Wang.

In the opinion of the two researchers, “effective global chemicals management” is necessary in order to achieve the goal of a sustainable recycling economy for plastics. This would have to be transparent and independent and hazardous substances would have to be recorded in full. In addition, “open and easy access to reliable information is vital.”

The study appeared in the journal Environmental Science & Technology.

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