KOCHI: Plastic debris have choked our land, contaminated the oceans and endangered marine life. The World Health Organisation has decided to review the potential risks of microplastics in view of a recent study by the State University of New York in Fredonia, which said around 90 per cent of bottled water available in the market has alarming levels of microplastics - particles that are small enough to be ingested. The University analysed 259 bottles of water from 19 locations in nine countries, one of which happens to be Delhi. The study gains significance in the background of another study that found microplastic particles in the ocean are finding their way into the human body through seafood. These revelations reinforce the findings of a team from the School of Environmental Sciences at Mahatma Gandhi University, Kottayam, regarding the presence of microplastics in the Vembanad Lake.
Microplastics have been increasingly detected in marine and freshwater environments, and there are growing concerns about the health hazards posed by them. According to experts, more than the plastic particles, toxic substances such as heavy metals and phthalates in these plastic pieces can pose a health hazard to the aquatic environment and living organisms. Besides, the microplastics can serve as a vector of pathogenic micro-organisms. “Though the impact of these microplastics on human health is yet to be established, there exists a strong base to consider it as a potential threat to human health due to their chemical composition as dyes, plasticisers and other chemicals are added during the manufacturing process,” said School of Environment Sciences Associate Professor E V Ramasamy.
“Their large surface to volume ratio facilitate the accumulation of aquatic contaminants like heavy metals; persistent, bioaccumulative and toxic compounds such as pesticides and other micropollutants on their exposed surfaces. When aquatic organisms like fish, crab and prawn consume these microplastics, it enters the food web of the aquatic system and finally reaches human beings with a cocktail of hazardous pollutants through the contaminated aquatic species.”
Accumulation of microplastics in the marine environment has been well-documented, while studies on freshwater bodies like lakes, rivers and estuarine systems are scarce. Only three studies have been conducted in India on the presence of microplastics in aquatic environment. While the studies conducted in Gujarat (2006) and Maharashtra (2013) were on the presence of microplastics in marine environment, the third one was on its impact on inland water bodies. A research team consisting of Ramasamy and Sruthy S from The School of Environmental Sciences at Mahatma Gandhi University, Kottayam reported in 2016 the first ever study on microplastics in the sediments of a lake in the international journal Environmental Pollution published by Elsevier.
The researchers collected sediment samples from ten locations above and below the Thanneermukkom Bund.“The result was alarming,” said Ramasamy. “All the samples examined by the team had microplastic content indicating its extensive distribution in the lake. The abundance of microplastics recorded from the sediment samples of the lake is in the range of 96-496 particles m-2. This is comparable with the reports available across the globe and it is also on the higher side of a few reports. Polyethylene (PE) is the most abundant category of polymer observed in the microplastics of the lake followed by polypropylene (PP) and polystyrene (PS). These polymers are extensively used in packaging materials, rigid plastic articles being used in day-to-day life, plastic furnishing, textile floor cover and fishing nets.”
Vembanad Lake - a freshwater/estuarine system - is the largest lake in Kerala and forms a part of the Vembanad wetland system recognised as a Ramsar site. The lake receives discharge from several rivers and many streams and canals, and is a sink for many contaminants including heavy metals. As these rivers and streams flow through densely populated urban stretches, the possibility of occurrence of microplastics in the lake sediments is high.
1 Microbeads of less than one mm size flow into the drains from our washrooms and enter the water bodies through streams and rivulets. These micro-particles can reach the tap water as our major potable water projects are located along the banks of major rivers.
2 According to experts, the microbeads may have even reached the ground water resources as the analysis of bottled water samples from across the world has suggested high microplastic content. It may be noted that many mineral water suppliers in India draw water from ground water resources.
3 The possibility of controlling microplastics/ plastics at the source is to be explored seriously. For, once microplastics are released into the environment, there is very little that can be done to limit their distribution and impact.
