Complexity of plastics make it impossible to know which are dangerous

https://www.eurekalert.org/pub_releases/2019-09/nuos-cop091319.php

News Release 17-Sep-2019
Norwegian University of Science and Technology

A lot of people worry about microplastics and plastic pollution, but not as many of us are aware of the large number of chemicals we encounter in plastic products that we use every day.

Researchers know of more than 4,000 chemicals that are currently used in plastic food packaging. But with more than 5,000 different types of plastic on the market, the number of chemicals used to make plastics is likely even larger.

"The problem is that plastics are made of a complex chemical cocktail, so we often don't know exactly what substances are in the products we use. For most of the thousands of chemicals, we have no way to tell whether they are safe or not," says Martin Wagner, a biologist at the Norwegian University of Science and Technology (NTNU). "This is because, practically speaking, it's impossible to trace all of these compounds. And manufacturers may or may not know the ingredients of their products, but even if they know, they are not required to disclose this information."

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"We studied eight types of plastics commonly used to make everyday products, such as yogurt cups and bath sponges, and examined their toxicity and chemical composition. Three out of four products contained toxic chemicals," Lisa Zimmermann, Wagner's colleague and first author of the study, says.

The researchers used cell cultures to investigate the effects of the mix of chemicals in each product. They found that many plastics contain chemicals that induced general toxicity (six out of ten products), oxidative stress (four out of ten) and endocrine-disrupting effects (three out of ten).

It is impossible to pinpoint specifically which chemicals were the culprits: the research group discovered more than 1,400 substances in plastics but identified only 260 of them. That means that most of the plastic chemicals remain unknown and cannot be assessed for their safety.

Given that, the authors were able to conclude that plastic chemicals in polyvinyl chloride (PVC) and polyurethane (PUR) were the most toxic. Compared to PVC and PUR, polyethylene terephthalate (PET) and high-density polyethylene (HDPE) were less toxic.

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