Biodegradable plastic from sugar cane also threatens the environment

Newswise — Cane sugar-derived plastic also endangers the ecosystem. Scientists from the University of Gothenburg have discovered that fish alter their conduct when subjected to the aforementioned bio-based plastic.

Conventional petroleum-based plastic has overwhelmed the planet, permeating all living organisms with microplastics. This situation has prompted extensive investigations into alternatives that biodegrade more rapidly in the natural environment. Cane sugar-derived bio-based polymers emerge as a viable choice. Among them, poly-L-lactide (PLA) stands out as the most prevalent bioplastic, employed in various applications such as 3D printing, textiles, food packaging, disposable utensils, and more.

PLA plastic changed the behaviour of perch

Biodegradable plastics, despite their eco-friendly reputation, can still exert detrimental effects on the natural world. Azora König Kardgar, a doctoral student at the University of Gothenburg, has made a noteworthy discovery regarding the influence of bioplastics on small perch. Over a span of six months, Kardgar observed a noticeable shift in the behavior of these fish when exposed to bioplastic-infused fish food. They exhibited heightened reactivity towards fellow perch, deviating from their normal behavior. Furthermore, there were indications of reduced mobility, altered shoaling patterns, and modified responses to potential threats.

"Toxicological assessments focusing on animal behavior are exceedingly infrequent. Typically, scientists prioritize examining physiological alterations. While we observe discernible impacts of PLA plastic on fish, the underlying cause eludes our vision," explains Azora.

Since this study specifically investigated PLA microplastic particles, the researchers decided to conduct additional tests involving the feeding of perch with kaolin particles, a white clay commonly employed in porcelain production and paper coating. The fish subjected to kaolin exhibited slight behavioral modifications. However, it was observed that the male sex hormone and certain gene expressions in the fish were disrupted, including their stress response.

PLA is not an environmentally friendly option

According to Azora, "It is evident that PLA poses risks to fish, therefore it should not be marketed as an environmentally benign substitute for conventional plastic. Instead, it should be regarded on par with standard plastic."

During the experiment, one group of fish was fed food containing 2 percent PLA, which approximates the concentration typically utilized in previous studies involving conventional petrochemical plastic. Another group of fish received a diet with a 2 percent kaolin content. Additionally, a control group of perch was fed uncontaminated food for comparative purposes.

Scientific paper in Science of the Total Environment https://www.sciencedirect.com/science/article/pii/S0048969723020442