A PhD student at the University of Gothenburg proves that PLA is as harmful as synthetic plastics

University of Gothenburg PhD student Azora König Kardgar has discovered that the bioplastic polylactide (PLA) has a negative effect on the behavior of fish. According to a paper published in ScienceDirect, the research results challenge the popular belief that bioplastics are an eco-friendly alternative to traditional plastics.

Fossil fuel-based plastics are one of the main sources of pollution on the planet, and microplastics, formed as a result of their degradation in the natural environment, are present in all living organisms. This has prompted scientists to intensively research alternatives that degrade faster in nature. One such option is bio-based polymers, e.g. on sugar cane. The most popular bioplastic of this type is poly(L-lactic acid), i.e. popular PLA, which is used in 3D printers, textiles, food packaging or disposable cutlery.

Azora König Kardgar, discovered that small perch that had been exposed to bioplastic in fish food for six months changed their behavior and, for example, reacted much more strongly to encounters with other perch than usual. Additionally, signs of decreased locomotion, altered shoaling ability, and altered reaction to approaching danger were observed.

“Toxicological experiments analyzing animal behavior are very rare. Most often, researchers analyze physiological changes. We can see that something in PLA is causing the fish to change, but we can’t see what?” says Azora.

Researchers working with Azora also tested feeding perch particles of kaolin, a white clay used to make porcelain and to coat paper. Kaolin-fed fish showed slight behavioral changes. Nevertheless, effects on the male sex hormone and inhibition of certain genes in fish, such as stress response, have been observed.

“We see that PLA is not harmless to fish, so it should not be marketed as an eco-friendly alternative to regular plastic. It should be considered equivalent to ordinary plastic,” says Azora.

The fish were fed a diet containing 2 percent PLA for six months, roughly equivalent to the concentration of common petrochemical plastic used in previous studies. The amount of kaolin given to the other groups of fish was also 2 percent. In addition, a control was carried out on a group of perch fed with uncontaminated food.

Research findings suggest that bioplastics, despite being advertised as being more environmentally friendly, may still have a detrimental effect on biological life. This leads to the question, what are the truly green alternatives to traditional plastics?

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