Researchers are now trying to understand how microplastics enter and affect the host
Researchers are now trying to understand how microplastics enter and affect the host
Upendra Nongthomba, Professor in the Department of Molecular Breeding, Evolution and Genetics (MRDG) at the Indian Institute of Science (IISc.), would love to visit the backwaters of the Krishna Raja Sagar (KRS) Dam and eat fried fish on the shore. of Kaveri river. But in recent days, he has been noticing physical deformities in some fish and has begun to wonder whether it has anything to do with water quality.
Published in the journal Prof. A new study led by Nongthomba Ecotoxicology and environmental safetysuggests that pollutants such as microplastics can cause growth defects in fish including skeletal deformities in the Cauvery River.
“Water is essential for everyone including animals and plants. When it is polluted, it is capable of causing diseases including cancer,” Prof. Abas Toba Enifowoshe, a PhD student in Nongthomba’s lab and first author of the study, said.
Pro. Nongthomba’s laboratory conducted a comprehensive study of pollution in the KRS Dam and its potential effects on fish. They collected water samples from three different locations with different speeds of water flow – fast flowing, slow flowing and steady – because the speed of water is known to affect the concentration of pollutants.
In the first part of the study, the team analyzed the physical and chemical parameters of the water samples. All except one parameter were within the prescribed limits. The exception was dissolved oxygen (DO), the level of which was much lower than that occurring in samples collected from slow-flowing and stationary sites. The waters of these sites also contained microbes such as Cyclops, Daphnia, Spirogyra, Spirochaeta and E. coli, which were well-known bio-indicators of water contamination.
Using a technique called Raman spectroscopy, the team detected microplastics – tiny pieces of plastic that are often invisible to the naked eye – and toxic substances containing the cyclohexyl functional group (the atoms in a compound that determine its chemical properties). Detect chemicals.
Microplastics are found in many household and industrial products, and chemicals containing the cyclohexyl group, such as cyclohexyl isocyanate, are commonly used in the agriculture and pharmaceutical industries.
In the second part of the study, they investigated whether pollutants in the water could be responsible for the developmental abnormalities seen in wild fish. They treated embryos of the well-known model organism zebrafish with water samples collected from three sites, and found that those exposed to water from both slow-flowing and stationary sites showed skeletal deformities, DNA damage, and early cell death. , heart damage, and increased mortality. These defects were observed even after filtering the microbes, suggesting that microplastics and cyclohexyl functional groups are responsible for diseases in fish.
The researchers also found unstable molecules called ROS (reactive oxygen species) in abnormally developed fish cells. ROS build-up is known to damage DNA and affect animals, as was observed in fish treated with water from slow-flowing and stagnant sites. Other studies have shown that microplastics and chemicals with a cyclohexyl group decrease dissolved oxygen (D), which in turn triggers ROS accumulation in animals such as fish.
Since millions of people depend on water from the Cauvery River and a recent study from the Netherlands showed that microplastics can enter the bloodstream of humans, Prof. “The concentrations we have reported may not yet be dangerous for humans, but long-term effects cannot be ruled out,” Nongthomba said. They said.
But before they can answer the question conclusively, they need to understand how microplastics actually enter and affect the host. “It’s something we’re trying to address right now,” Prof. Nongthomba said.