Microplastics in Cauvery cause fish deformity, pose health risks: Study
Microplastics in the Cauvery river have been identified as one of the major reasons for deformities in fish and other impacts on marine life, according to a study conducted by the Indian Institute of Science (IISc)
Microplastics in the Cauvery river have been identified as one of the major reasons for deformities in fish and other impacts on marine life, according to a study conducted by the Indian Institute of Science (IISc).
Releasing its report on Monday, the IISc said, “Pollutants like microplastics may be causing growth defects in fish, including skeletal deformities, in the Cauvery River, a new study reveals. Published in the journal Ecotoxicology and Environmental Safety.”
“Water is essential for everyone, including animals and plants. When it is polluted, it is capable of causing diseases, including cancer,” added Abass Toba Anifowoshe, a PhD student in Nongthomba’s lab and the first author of the study.
A team, led by Upendra Nongthomba, professor at the Department of Molecular Reproduction, Development and Genetics (MRDG), conducted a comprehensive study of pollution at the KRS Dam and its potential effects on fish. They collected water samples from three different locations, with varying speeds of water flow – fast-flowing, slow-flowing, and stagnant – since water speed is known to affect the concentration of pollutants.
The findings come when the use of plastic and unscientific disposal of waste into water bodies has increased, especially since the covid-19 pandemic outbreak after which there has been an increase in single-use plastic that stems from fear of contracting the virus, according to experts.
Cauvery river water is the lifeline for southern districts of Karnataka, Tamil Nadu, parts of Kerala and Puducherry. The river is the main source of drinking water for Bengaluru and its over 12 million residents.
Using a technique called Raman spectroscopy, the IISc team detected microplastics – minute pieces of plastic often invisible to the naked eye – and toxic chemicals containing the cyclohexyl functional group (functional group refers to atoms in a compound that determine its chemical properties).
“Microplastics are found in several household and industrial products, and chemicals containing the cyclohexyl group, such as cyclohexyl isocyanate, are commonly used in agriculture and the pharmaceutical industry,” the study stated.
A research paper that studied the impact of pharmaceutical and personal care products released into Bengaluru’s water bodies stated that the risks of side effects to aquatic life and humans, who consume it indirectly, are increasing, HT reported in May 2021.
The study, conducted between the monsoon period in October 2018 and the pre-monsoon period in February 2019, across the Arkavathi River in Bengaluru established the high level of harmful content entering surface water streams.
Arkavathi is a tributary of the Cauvery River and flows for a length of 193 kms, and the basin area is around 4253 square kilometres, according to the study.
According to the Karnataka State Pollution Control Board (KSPCB), over 708 kilometres of seven major rivers and their tributaries have levels of contamination ranging from Class ‘B’ (waters for use for organised outdoor bathing) all the way to “D” (waters to maintain aquatic life). Of the 98 water quality monitoring stations in the in the state on this stretch, at least 42 have reported serious, if not dangerous, levels of pollution, data showed.
Untreated water, industrial effluent and other polluting elements are often let into these water bodies, which increases the presence of harmful pollutants and seeps into groundwater, food crops, animals and even humans when they consume the same.
Bengaluru requires around 1,400 million litres per day, and wastewater recycling infrastructure has a capacity of around half that, and actual recycled water is around 500 mld, according to official data.
A large portion of used water, including those with soaps, detergents and other cleaning products, is let out of drains that, in turn, make their way into other water bodies like rivers and lakes. Discharge of pharmaceuticals happens through humans.
The IISc study also analysed the physical and chemical parameters of the water samples.
“All but one of them fell within the prescribed limits. The exception was dissolved oxygen (DO), whose levels were much lower than they needed to be in samples collected from the slow-flowing and stagnant sites. Water from these sites also had microbes such as Cyclops, Daphnia, Spirogyra, Spirochaeta and E. coli, well-known bio-indicators of water contamination,” according to the authors.
The study also revealed abnormalities in wild fish like zebrafish, with water samples collected from the three sites, and found that those exposed to water from the slow-flowing and stagnant sites experienced skeletal deformities, DNA damage, early cell death, heart damage, and increased mortality. These defects were seen even after microbes were filtered out, suggesting that microplastics and the cyclohexyl functional groups are responsible for the ailments in the fish.
“The concentrations we have reported may not be alarming yet for humans, but long-term effects can’t be ruled out,” the authors added on the risk of consuming contaminated fish.