MIT-WPU research finds microplastics in freshwater fish in Pune, flags emerging food-chain concern

Researchers at MIT World Peace University (MIT-WPU), Pune, have detected microplastics in freshwater fish commonly consumed in the city, highlighting the need for greater understanding of how plastic pollution moves through freshwater ecosystems and enters the food chain.

The research is being conducted as part of an ongoing study by Simran Singh, PhD Scholar, Department of Environmental Studies, MIT-WPU, under the guidance of Dr Soma Mishra.

The study is funded through the MIT World Peace University Seed Grant and focuses on commercially consumed freshwater fish, particularly Rohu and Tilapia, to examine the occurrence, characteristics and potential sources of microplastic contamination, as well as its implications for freshwater ecosystems and human health.

The research began with a detailed mapping of Pune's freshwater fish supply chain. Rather than focusing only on retail markets, the researchers surveyed major wholesalers and distributors, which serve as key entry points for freshwater fish into the city. Pune was divided into four geographical zones for the survey, covering the city's major distribution networks.

The researchers interviewed 26 wholesalers and distributors across Pune. Based on the survey, the study estimates that approximately 37-40 tonnes of freshwater fish enter the Pune market every day, with Rohu and Tilapia among the commonly traded species. A significant proportion of the supply comes from aquaculture systems, while fish are also transported to Pune from states and regions including Andhra Pradesh, Gujarat, Ratnagiri, Mumbai and Kolkata, reflecting the extensive interstate nature of the city's freshwater fish supply chain.

The laboratory investigation detected microplastics in the freshwater fish samples examined. The particles identified included fibres, fragments and pellets, which are among the commonly reported forms of microplastics found in freshwater environments. Based on the detected levels and local consumption patterns, the study estimates that an individual consuming an average of 250 grams of freshwater fish twice a week over 50 years could potentially ingest between 93,600 and 124,800 microplastic particles.

The researchers, however, emphasise that the particle count cannot be directly equated to the number of plastic bottles or other plastic items, as the mass and potential health implications depend on factors including particle size, polymer composition and associated contaminants. Detailed quantitative analysis and polymer characterisation are currently underway as part of the ongoing doctoral research.

The study aims to establish baseline scientific data on freshwater microplastic pollution in Pune, a rapidly urbanising city, and contribute to a better understanding of the pathways through which microplastics may move from freshwater environments into the food chain. The findings could support evidence-based approaches to plastic waste management, wastewater management, freshwater ecosystem conservation and food safety.

The research also received recognition at the National Scientist Round Table Conference (NSRTC), where Simran Singh was awarded the Third Prize for her poster presentation recently. "Plastic pollution is no longer just an environmental issue; it is becoming a food-chain issue. Understanding where microplastics originate, how they move through freshwater ecosystems, and how they eventually reach the fish we consume is essential for developing informed policies and sustainable solutions," Dr Mishra said.