One of the most common bioplastics in the world is harmful to fish, according to a new study.
Made from starches like corn or sugarcane, poly-L-lactide (PLA) is used in food packaging, textiles, cutlery, and a range of other bioplastic products.
A study published in Science of the Total Environment has found PLA microparticles change the juvenile behaviour of a common freshwater fish: the European perch (Perca fluviatilis).
After six months of exposure to the sorts of miniscule PLA particles that can turn up in waterways, baby perch reacted more to other fish, moved less, and had a different ability to form shoals and react to danger.
The researchers fed 60 juvenile perch on either normal food pellets, pellets that were 2% PLA microplastics, or pellets that were 2% kaolin microparticles (a clay used in porcelain and paper coating) for six months.
While they didn’t see any changes in the PLA-fed fish’s life cycles or other physiological features, there were clear behavioural differences.
“Toxicological experiments that analyse animal behaviour are very rare,” says lead author Azora König Kardgar, a doctoral student at the University of Gothenburg, Sweden.
“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.”
Kaolin particles did cause several noticeable changes, including to a male sex hormone, and the expression of certain genes. There were also some minor behavioural changes in PLA fish compared to the control group.
“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,” says Azora.
In their paper, the researchers call for more studies on the possible effects of bio-based plastics on aquatic life.
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