High concentration of microplastics entering human food chain in Tamil Nadu

Water, sediment, fish and shellfish samples collected in TN show microplastics have crept deep inland and into the food chain in varied concentrations.
Ghost nets are the major source of microplastic in marine environment. These discarded fishing gear also threaten the marine life, especially turtles and corals.
Ghost nets are the major source of microplastic in marine environment. These discarded fishing gear also threaten the marine life, especially turtles and corals.

CHENNAI: When it comes to environment protection, we talk about air and water pollution since it’s visible and everyone feels it. However, there is an invisible pollutant that has crept deep into our human food chain, but is least understood - microplastics, which are tiny plastic particles less than 5 mm in diameter.

A three-year comprehensive study titled: “Assessment of microplastics in coastal areas, estuaries and lakes in Tamil Nadu” was conducted by Thoothukudi-based Suganthi Devadason Marine Research Institute (SDMRI) with the funding support of Tamil Nadu government.

The 500-page study report, a copy of which is available with The New Indian Express, was released during the recently concluded TN Climate Summit. The results are startling. Based on polymer type and shape, it was established that the biggest contributor is the single-use plastics, which are already banned in Tamil Nadu and a huge public campaign is currently undertaken.

For the study, water, sediment, fish and shellfish samples were collected from 112 locations in 18 districts across the state, including 51 coastal locations in 14 coastal districts, 19 estuaries and 42 lakes. Lake in tourist hotspots such as Kodaikanal, Ooty and Yercaud, were also part of the study.

The results show that there was not even a single water body that was free from microplastics. The finfish and shellfish, which are consumed widely, are ingesting them mistaking microplastics as food. In coastal waters, the abundance of microplastics ranges between 23 to 155 items per litre (water) and 37 to 189 items per kg (sediment). In estuaries, it ranges from 31 to 154 items per litre and 51 to 171 items per kg. Among the 39 rural and urban lakes studied, urban lakes have a higher abundance of microplastics.

Human exposure to microplastics

In the study, the extent of human exposure to microplastics was estimated based on the mean number of microplastics per kg taken per day from fish muscle, called estimated daily intake (EDI). Fisheries Policy Note (2020-21) reports that an average consumer in Tamil Nadu takes 9.83 kg of fish per year. At this rate, people consume 709 items (West Coast), 830 items (Gulf of Mannar), 792 items (Palk Bay) 1,076 items (Coromandel Coast) of microplastics.

Coastal shellfish consumers unconsciously take as many as 1,981 items (West Coast), 1,238 items (Gulf of Mannar), 1,517 items (Palk Bay) and 3,017 items (Coromandel Coast) per year via shellfish consumption. In estuaries, people consume 781 items of microplastics per year via fish and 2,809 items/year via shellfish consumption. Its concentration in shellfishes is higher than in fin fishes since shellfishes are eaten whole. Consumers of shellfishes incur greater health risk, the report said.

When contacted, Supriya Sahu, Additional Chief Secretary, Environment, Climate Change and Forest Department, told this newspaper: “The report confirms what we feared. We have to get rid of the single-use plastics. On the one hand, the Meendum Manjappai campaign, which was launched by Chief Minister M K Stalin, is bringing in behavioral changes. We are also pushing hard to implement the Extended Producers Responsibility (EPR). Data shows only 10% of plastic produced is recycled and the remaining 90% is either unscientifically disposed of or ends up in dumpsites. Only EPR can ensure the plastics that are produced are taken back. So far, 70 companies have registered with us for compliance and in the next two months we will bring all other companies onboard. We engaged specialised EPR consultants for the job.”

Microscopic view of microplastics.
Microscopic view of microplastics.


For comparison and benefit of policy makers, the study divided the coast into four sections - Coromandel coast, Palk Bay, Gulf of Mannar coast and west coast. The results show the hotspot for the microplastics was the Coromandel coast. The highest abundance was found in Kovalam near Chennai. Even among estuaries, surface water in Adyar estuary in Chennai carries the highest abundance of microplastics in the range of 124 to 154 items per litre and its sediment has 147 to 171 items per kg during both summer and monsoon seasons.

When it comes to lakes, again Chennai’s Chembarambakkam Lake has the highest concentration and among tourist lakes, Ooty tops the list followed by Kodaikanal and Yercaud.

SDMRI Director J K Patterson Edward, who is one of the authors of the report, told TNIE: “It’s understandable that water samples collected on Coromandel stretch exhibited high concentration of microplastics. The rivers, example Chennai rivers, carry loads of plastic waste from urban spaces into the estuaries and then to sea. Most of the development is also here.

” M Jayanthi, chairperson, Tamil Nadu Pollution Control Board (TNPCB) who is also one of the authors of the study, told TNIE: “This is the first of its kind study. As a follow-up, 47 lakes in western and eastern districts were selected for phase-2 study of microplastics. Next, northern and southern district lakes will be studied. Four rivers - Thamirabarani, Vaigai, Vellar and Palar - are also being studied. This will help us identify the problematic areas and take management interventions.”

Sources & measures proposed

Analysis of the coastal, estuaries and lake water and sediment indicates that the environment is polluted dominantly with fibre-shaped, different sized, diverse polymer-type microplastics. Single-use plastic bags, cups, straws, and bottles are widely used due to their low cost, extremely light weight, large capacity, and easy storage.

Due to the widespread commercial usage, a large number of plastic products are disposed of in the environment, including roads, river banks, and in the land around cities.

Among different coastal sites studied, the highest concentrations of microplastics are found in those which are in close proximity to the river mouths (Coromandel Coast and Palk bay) during the monsoon season. The greater concentration of microplastic particles in the Coromandel coast could be due to their transportation from major rivers like Kosasthaliyar, Cooum, Adyar etc. Even though the rivers are not perennial, most of them pass through densely populated areas, with relatively higher freshwater flows during southwest and northeast monsoon.

The industrial pollution comes from petroleum refineries, thermal power plants, tanneries, pulp and paper industries, chemical industries and non-metallic mineral industries that discharge plastics and other pollutants either directly into water bodies that connect to the sea or indirectly into land and air that are transported to the coast via rainfall runoff and wind. Fishing events are one of the most significant sources of offshore marine litter responsible for microplastic pollution. Ships also contribute significantly to marine litter by dumping plastic packaging materials, as well as marine industries (such as aquaculture, oil rigs and power generating boats). Additionally, coastal tourism and coastal landfills play an important role as a source.

The study called for regulation of production and consumption through bans or taxes of plastic products that are harmful to the environment, without compromising public health or food safety. It suggests reducing the consumption of plastics through removal of unnecessary packaging (e.g., double packaging), labelling and by providing eco-friendly alternatives to plastics when possible without unintended consequences. It also recommended long-monitoring to evaluate the temporal variability and to identify hotspots.

The Chief Editor of the report Dr Andy Booth, Chief Scientist, Climate and Environment Department SINTEF Ocean AS, Trondheim, Norway says “Despite the high profile nature of plastic pollution, we are still trying to fully understand the environmental and human health impacts. The study report represents an important national and international contribution to the scientific research field and to our growing understanding of the societal challenge of plastic and microplastic pollution. This is a critical knowledge base from which robust and effective control measures can be developed and implemented”

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