A new study conducted by researchers from the Manipal Institute of Technology (MIT), MAHE, and Cochin University of Science and Technology (CUSAT) has uncovered the widespread presence of microplastics in two of the most commonly consumed freshwater fish species in coastal Karnataka. Microplastics are tiny plastic particles smaller than 5 millimeters, often invisible to the naked eye, and their detection in these fish raises significant concerns about plastic pollution and its implications for food safety.
Study Details and Findings
The research team, comprising Kuruveetil Manikandan Ashitha, Anjali Tamrakar, Gopika Melethil, and Anish Kumar Warrier, examined samples of rohu (Labeo rohita) and pangas or basa (Pangasius pangasius). The findings were published in the Journal of Toxicology, an international peer-reviewed journal by Wiley Publications. Microplastics were found in every fish sample analyzed.
The scientists analyzed five organs: the gut, gills, liver, gonads, and muscle tissue. A total of 1,510 microplastic particles were detected. Rohu exhibited higher contamination levels, averaging 58 microplastic particles per fish, compared to 42 particles in pangas or basa. More than 95 percent of the particles were fibers, predominantly blue and black in color.
Sources and Pathways of Microplastics
According to Anish Kumar Warrier, freshwater bodies such as rivers, lakes, and reservoirs not only support aquatic biodiversity but also serve as major pathways for plastic waste from land to oceans. Microplastics originate from various sources, including discarded plastic waste, synthetic textile fibers, tire wear, wastewater discharge, agricultural runoff, and atmospheric deposition. Studies estimate that 1.2 million to 2.4 million tonnes of plastic enter oceans annually through freshwater systems.
Organ-Specific Accumulation
The study found that rohu accumulated the highest number of microplastics in its gills and digestive tract, while basa showed a more uniform distribution across organs. Of particular concern was the presence of microplastics in muscle tissue, the edible part of the fish, and in gonads, the reproductive organs. While the detection of microplastics in gonads does not confirm biological damage, it indicates a potential reproductive risk that warrants further investigation. The presence of particles in internal organs such as the liver suggests that microplastics can move through the fish's body and accumulate over time.
Ecological and Health Implications
The researchers warned that microplastics can impair feeding, immunity, and reproduction in aquatic organisms. They can also carry harmful contaminants such as heavy metals and toxic organic pollutants through the food chain. The study identified polyester and polypropylene as the dominant plastic polymers in the fish samples, linking contamination to textile fibers, fishing gear, aquaculture infrastructure, and poor waste management practices.
Call for Action
The researchers called for improved waste management, greater public awareness, and further research to better understand the long-term ecological and human health impacts of microplastic pollution. This study highlights the urgent need to reduce plastic leakage into freshwater systems and strengthen efforts to protect aquatic ecosystems, food security, and public health.
