Reusable plastic bottles, the eco-friendly gesture potentially dangerous to health

When you want to reduce your daily waste, swapping mineral water bottles for an infinitely reusable water bottle is the first step that many adopt. Light, unbreakable, therefore nomadic, plastic water bottles have been popular in recent years. At work, at sport or on a walk, they follow us everywhere to quench our thirst.

A gesture that wants to be good for the planet, but is it really good for our health? Have you ever found that your water tastes weird in your water bottle? The answer is not really reassuring. A study by two researchers from the University of Copenhagen in Denmark, published in the scientific journal Journal of Hazardous Materials​points out the risks of chemical substances contained in these plastic bottles passing through the water.

Nearly 400 chemicals released into the water

As part of their study, the two researchers filled several types of water bottles with tap water: new, used, dishwasher-safe or with an extra rinse. After 24 hours, the scientists analyzed the composition of this water and found migrations in the water of chemicals contained in the plastic of the gourd. “Many people use these bottles, but few know about the migration of chemicals that the plastic causes to pass through the water”, underline the researchers in the preamble to their study.

However, they found 400 chemical substances in the water with which the canteens were filled. “We were surprised by the large amount of chemicals we found in the water after 24 hours in the bottles. There were hundreds of them, including substances never before found in plastic, as well as some potentially harmful to health,” said study co-author Prof. Jan H. Christensen, professor of environmental analytical chemistry. at the Department of Plant and Environmental Sciences of the University of Copenhagen.

And the list is scary. Among the substances identified: chemicals aimed at softening the plastic or release agents. And that’s not all: they also identified the presence of diethyltoluamide or DEET in the water, a powerful repellent found in mosquito repellent sprays. As well as photo-initiators. However, “the photoinitiators are those who worry the most, they are known to be carcinogenic or considered as endocrine disruptors”, indicate the authors in a press release.

Even worse after going through the dishwasher

If you are used to putting your water bottle in the dishwasher to make your life easier, you will learn that this is not necessarily the best idea. “The most toxic substances that we identified appeared after placing the bottle in the dishwasher,” said Selina Tisler, researcher and lead author of the study. “Probably because washing wears out the plastic and thus increases leaching”, the passage of substances from plastic to water, analyzes the researcher.

Not only does washing the bottle in the dishwasher not reduce the content of potentially toxic substances in the plastic, but it adds a long list! In this case, “more than 3,500 substances derived from the dishwasher cleaner,” adds Professor Christensen.

An unknown cocktail effect

And if many of these substances found in water are unknown, even for those identified by scientists, “we do not have information relating to their toxicity for 70% of them”, point out the two researchers. And even after an extra rinse, there are still 500 chemicals in the water. For pure water, it will be necessary to iron. However, “it is not because these substances are in the water that the water is toxic and affects us, us humans, tempers Selina Tisler. But the problem is that we don’t know. And in principle, it is not good to drink residues of soap or other chemicals. »

But faced with a cocktail effect unknown to date, scientists recommend a very simple change in the name of the precautionary principle: opt for a glass bottle. The trouble is that for now, scientists know very little about the toxicity of all these substances. “The study illustrates how little is known about the chemicals emitted by the products with which our food and drink come into contact,” says Prof. Christensen. With this study, the two researchers hope to move the lines: “Companies should be more attentive to the products they buy from suppliers and that they require more of them to know the substances present in what they manufacture. . »

Watch out for bottles

And exposure to substances released by reusable plastic containers also concerns babies, since the problem raised by Danish scientists has already been highlighted with regard to baby bottles. In March 2021, ANSES warned against bisphenol B, a chemical substance used in particular to manufacture baby bottles in certain countries outside the European Union as an alternative to bisphenol A, recognized as an endocrine disruptor. However, according to ANSES, the endocrine disrupting effects of bisphenol B would be similar “even slightly more pronounced” than with bisphenol A. What push ANSES to propose that bisphenol B as a “substance of very high concern” in the European REACH Regulation, to “avoid the industrial uses of this chemical substance on the European continent as a replacement for bisphenol A, and to oblige importers of consumer articles to declare its presence as soon as it exceeds a threshold of 0.1% in their composition.

In 2020, another study published in the journal nature food revealed that polypropylene bottles could release up to 16 million microplastics per litre. If the researchers recommended never heating the bottle in the microwave, they first advised to prefer glass bottles.

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