The story so far:
Microplastics, especially nylon fibres, seem to be present rather sparsely in Chennai’s beach sediments but could still wreak long-term ecological damage, new research has cautioned. A study by researchers at V.O. Chidambaram College in Thoothukudi examined the abundance, sources, and ecological risks of microplastics from beach sediment samples from 15 sites along the Chennai coast. The findings show fibres dominating, with most particles smaller than 1000 m.
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Why does low abundance not mean low risk?
“This study is important because it shows that microplastics are already present in Chennai’s beach sediments, even if we don’t always see them,” Sekhar Selvam, senior assistant professor at the Department of Geology, V.O. Chidambaram College, Thoothukudi, said. “What is new here is that the problem is not just the amount of plastics but also the type of plastics. We found that most of the microplastics are nylon fibres, which are more harmful than many other plastics.”
In other words, even though Chennai’s beaches have fewer microplastics than many global ones, the risk to marine life remains significant.
“This study helps us understand that early-stage pollution can still cause long-term damage if ignored,” Dr. Selvam said.
While there have been several studies worldwide about microplastics, data from rapidly urbanising tropical coastal regions like Chennai remain scarce, Shaji Erath, professor of geology at the University of Kerala, Thiruvananthapuram, said.
He added that the new study thus “sheds new light by demonstrating that low overall microplastic abundance does not necessarily imply low ecological risk.”
An additional insight from the study is the disconnect between abundance-based assessments and risk-based evaluations, Mr. Erath said. Traditional monitoring often focuses on microplastic counts alone.
However, the study has shown that polymer type, shape, and aging characteristics are equally, if not more, important in determining ecological risk, he added.
What are the ecological concerns?
Ecological concerns in the study are chiefly centred on marine life and coastal ecosystems, Dr. Selvam said. Small organisms living in beach sand, such as worms, crabs, and shellfish, easily ingest the small plastic fibres, which can go on to block or injure their digestive tracts. Toxic compounds in plastics can also enter and poison their bodies.
Over time, these plastics move up the food chain and affect fish, birds, and other animals “So even small particles can slowly disturb the entire coastal ecosystem,” Dr. Selvam said.
According to Dr. Erath, besides feeding by marine microorganisms, plankton, and marine animals, hazardous polymers such as nylon pose higher ecological risks due to their persistence, chemical additives, and capacity to adsorb pollutants.
Fibre-shaped microplastics in particular can alter habitats by modifying the structure of sediments, affecting the benthic — or bottom layer — of seas and the microbial communities there, he explained. There could also be prolonged environmental exposure and long-distance transport of microplastics, highlighting the transboundary nature of microplastic pollution.
“These concerns collectively threaten coastal biodiversity, ecosystem stability, and biogeochemical processes,” he said.
How do human activities contribute?
Most microplastics found by the Chennai study team were clearly linked to human activities, according to Dr. Selvam. These include fishing, where damaged nets and ropes shed plastic fragments that break up into microplastics; synthetic clothes, which release minuscule fibres when they are washed; tourism and beach use; and urban sewage and stormwater drains that carry plastics into the sea.
“Simply put, everyday plastic use on land eventually reaches the coast,” Dr. Selvam said.
After reaching the coast, they reenter human bodies via seafood contaminated by microplastics, among other pathways. Seafood in particular can ferry both harmful chemical substances and disease-causing bacteria and other microorganisms into the body, causing tissues to become inflamed and affecting the hormonal and immune systems over longer periods.
“Research is still ongoing, but the concern is clear: what pollutes the ocean can eventually affect our health,” Dr Selvam said.
There have been similar findings from some other coasts. A July 2025 paper published in Environmental Earth Sciences studied select beaches in southern Goa and reported that fibres were the dominant microplastics shape while colourless and white microplastics were present in all sampled surface waters along beaches. The common plastics identified included polyethylene, polypropylene, polystyrene, ethylene vinyl alcohol, and polyurethane.
Is it too late to act?
Another study published in Environmental Quality Management in June 2024 assessed the prevalence of microplastics in water, sediments, and tissues of commercially important fish species along the Malabar coast in northwest Kerala. Six polymer types, including high density polyethylene (HDPE), polyethylene terephthalate (PET), and nylon dominated. This study also reported a notable abundance of transparent microplastic particles, measuring less than 1 mm in diameter, particularly in gastrointestinal and gill tissues. The researchers emphasised “the urgent need for the implementation of effective regulatory measures to mitigate plastic pollution in marine ecosystems”.
“Chennai still has a chance to act early,” according to Dr. Selvam. Right now, microplastic pollution levels are not so extreme in Chennai and better waste management, responsible fishing practices, and public awareness can still prevent a much bigger problem in the future, according to Dr. Selvam. “If we wait until the beaches are heavily polluted, it will be much harder and more expensive to fix. Early action is key.”
In the final analysis, the research has reinforced the need for timely policy-driven interventions, including better solid waste management, recycling of fishing gear, promotion of biodegradable alternatives, and public awareness, Dr. Erath said.
“These measures are essential not only for Chennai but for rapidly developing coastal cities of both west and east coasts, where urbanisation-driven plastic pollution is likely to intensify.”
(T.V. Padma is a science journalist based in New Delhi)
