Traditional plastic, made from fossil fuels, has saturated the planet, resulting in microplastics being present in all living organisms. This has led to extensive research for alternatives that decompose more rapidly in nature. One such option is bio-based polymers derived from cane sugar. Poly-L-lactide (PLA) is the most common bioplastic, used in 3D printing, textiles, food packaging, disposable cutlery, and other applications.
However, bioplastics also have a negative impact on biological life. Doctoral student Azora König Kardgar at the University of Gothenburg found that small perch exposed to bioplastics in fish food showed changes in behavior after six months. They reacted more strongly when encountering other perch than normal, showed signs of reduced movement, altered ability to form shoals, and changed reactions when threatened.
“Toxicological experiments that analyze animal behavior are very rare. Most commonly, researchers look at physiological changes. We can see that something in PLA plastic causes changes in the fish, but we can’t see what.”
This study examined PLA microplastic particles. In addition, the researchers tested the effects of feeding perch with kaolin particles, a type of white clay used for porcelain and paper coating. The fish fed with kaolin exhibited some minor changes in behavior. However, the male sex hormone was affected and some gene expressions in the fish were suppressed, including their response to stress.
“We see that PLA is not harmless to fish, so it should not be sold as an environmentally friendly alternative to ordinary plastic. It should be considered as equivalent to ordinary plastic.”