Plant-based plastics are just as harmful to health as traditional “petroleum” plastics. This is the conclusion reached by the authors of the largest study of the composition of bioplastics to date.
Details are set out in a scientific article published in the journal Environment International.
The raw materials for plastics are usually oil, coal or natural gas. But in recent years, there has been a growing interest in bioplastics derived from plant materials.
One of the reasons is that traditional plastics such as polyethylene and polypropylene do not decompose in nature for a very long time. As a result, mountains of plastic waste are formed. Still, they are not eternal, and their slow destruction leads to the formation of microplastic particles that flood the environment, entering the body of animals and humans. Chemists are striving to create materials that, if released into the environment, would quickly decompose into harmless substances (for example, carbon dioxide and water). An obvious way to this is to use components similar in composition to wood, fallen leaves and other substances familiar to the ecosystem.
In addition, oil, coal and gas contain a huge amount of different compounds, including toxic ones. During the production of plastics, such substances can enter both the plastic and the environment.
Finally, there are some buyers who are unreasonably convinced that all natural is better than artificial. This, of course, is a mistake: synthetic saccharin is much safer when consumed than the most natural and environmentally friendly pale toadstool. But the demand for bioplastics is fueled by this irrational belief as well.
Is “plastic from the garden” safer for human health than its traditional counterparts? This is the question the authors of the new study were trying to find out.
Scientists have tested 43 common product types. Many of them were designed for food contact: disposable cutlery, chocolate wrappers, beverage bottles, wine corks.
The items tested were made from nine of the most popular bioplastics. Among them were substances that received this proud title for a variety of reasons.
Thus, biopolyethylene is no different from ordinary polyethylene either in properties or in production technology from ethylene. The only difference is where this ethylene comes from (not from oil or gas, as usual, but from ethanol of plant origin). On the other hand, some of the plastics tested have much more rights to the prefix “bio-“: they consist mainly of cellulose or starch and quickly decompose in the trash.
However, all these such different materials have one thing in common: they contain many substances-impurities. Even in the “cleanest” plastic there were almost 190 different compounds, and in the “dirtiest” – more than 20 thousand. Eighty percent of the products contained at least ten thousand (!) Different chemicals. Moreover, most of them were found in “starch” and “cellulose” plastics. Perhaps the environmentally friendly main ingredient was not very practical as a material, and manufacturers made up for this with numerous additives.
Moreover, the “bouquet” of additional chemicals often depended not only on the type of material, but also on the type of product. So, bags made of biopolyethylene contained completely different impurities than wine corks from it.
Of course, the diversity of the line-up is not a reason for panic. After all, an ordinary fresh apple contains a great many different substances. But researchers have experimented with the effects of bioplastics on human cell cultures with alarming results.
It turned out that most “natural and environmentally friendly” plastics contain toxic substances. 67% of the samples were toxic, 42% caused oxidative stress in the cells, 23% had a hormonal-like effect. Some samples had two or three of the above unpleasant properties at once. Moreover, the most dangerous were, again, biodegradable plastics made from cellulose and starch.
For comparison, scientists tested products made from traditional plastics and, in general, did not find any difference.
“Bio-based plastics and biodegradable plastics are no safer than other plastics,” summarizes the article’s first author Lisa Zimmermann of Goethe University Frankfurt.
Of course, this does not mean that the very idea of bioplastics is flawed. But manufacturers should pay more attention to substances that are added (or accidentally fall into) such material during its manufacture, the authors warn.