A study conducted by the University of Gothenburg reveals potential environmental hazards associated with bioplastics derived from cane sugar. These so-called bioplastics, despite their biodegradable nature, can adversely affect the behavior of perch fish when exposed to them.
The widespread use of conventional plastic, derived from fossil oil, has led to the ubiquitous presence of microplastics in various life forms. Consequently, researchers have been exploring alternatives that can degrade more rapidly in the environment. One such alternative is bio-based polymers derived from cane sugar. Poly-L-lactide (PLA), the most commonly used bioplastic, finds applications in diverse areas such as 3D printing, textiles, food packaging, and disposable cutlery.
Azora König Kardgar, a doctoral student at the Department of Biological and Environmental Sciences at the University of Gothenburg, discovered that PLA plastic can significantly alter the behavior of perch fish. Over a six-month period, small perch exposed to bioplastics in their food exhibited heightened reactions when encountering fellow perch, reduced movement, impaired shoaling ability, and altered responses to threats.
“Toxicological experiments analyzing animal behavior are rare. Usually, researchers focus on physiological changes. While we observe behavioral changes in fish exposed to PLA plastic, we have yet to identify the underlying cause,” explains Azora.
In addition to studying PLA microplastic particles, the researchers also examined the effects of feeding the perch with kaolin particles, a white clay used in porcelain and paper coating. Fish fed with kaolin exhibited minor behavioral changes, including an impact on male sex hormones and the suppression of certain gene expressions related to stress response.
In the experiment, ground microplastics made from sugar cane-derived PLA were incorporated into fish food and fed to young perch. This allowed the researchers to observe the long-term effects of PLA plastic ingestion.
“We have evidence that PLA is not harmless to fish, and therefore, it should not be marketed as an environmentally friendly alternative to conventional plastic. It should be regarded on par with regular plastic,” warns Azora.
During the six-month study, fish were fed food containing 2 percent PLA, which is a concentration comparable to the levels used in previous studies involving petrochemical plastic. Similarly, another group of fish was fed food with 2 percent kaolin, while a control group received uncontaminated food.
Reference: “Chronic poly(l-lactide) (PLA)- microplastic ingestion affects social behavior of juvenile European perch (Perca fluviatilis)” by Azora König Kardgar, Dipannita Ghosh, Joachim Sturve, Seema Agarwal and Bethanie Carney Almroth, 12 April 2023, Science of The Total Environment.
Frequently Asked Questions (FAQs) about bioplastics
What are bioplastics derived from cane sugar?
Bioplastics derived from cane sugar are alternative plastics made from bio-based polymers, specifically poly-L-lactide (PLA). They are marketed as environmentally friendly alternatives to traditional fossil oil-based plastics.
How do bioplastics derived from cane sugar affect fish behavior?
A study conducted by the University of Gothenburg found that bioplastics derived from cane sugar, specifically PLA plastic, can alter fish behavior. Small perch exposed to these bioplastics in their food showed heightened reactions when encountering other perch, reduced movement, impaired shoaling ability, and altered responses to threats.
Are bioplastics derived from cane sugar environmentally friendly?
The study suggests that bioplastics derived from cane sugar, such as PLA, are not as environmentally friendly as previously believed. The research indicates that they can have negative impacts on fish behavior, raising concerns about their overall environmental impact. The study suggests that they should be considered on par with regular plastic rather than being marketed as environmentally friendly alternatives.
What other effects were observed in fish exposed to bioplastics?
In addition to behavioral changes, the study also examined the effects of feeding fish with kaolin particles, another substance used in various industries. Fish fed with kaolin exhibited minor behavioral changes, including impacts on male sex hormones and the suppression of certain gene expressions related to stress response.
What concentration of bioplastics was used in the study?
During the study, fish were fed food containing 2 percent PLA, which is a concentration similar to levels used in previous studies involving petrochemical plastic. This allowed researchers to observe the long-term effects of PLA plastic ingestion on fish behavior.
More about bioplastics
- University of Gothenburg: Link
- Poly-L-lactide (PLA) – Bioplastic Information: Link
- Science of The Total Environment Journal: Link