Groundwater Contamination: Microplastics Found at Deep Levels in Karnataka
A groundbreaking study conducted by researchers from the Indian Institute of Science (IISc) and Vellore Institute of Technology has uncovered alarming levels of microplastics in groundwater sources across eastern Karnataka. The research, published in the journal Current Science on March 25, detected these tiny plastic particles at depths ranging from 60 to 100 metres, sparking significant concerns about the safety of rural water supplies in the region.
Study Details and Sampling Methods
The investigation focused on borewell water collected from villages in six districts: Tumakuru, Ballari, Raichur, Chikkaballapur, Koppal, and Kolar. In November 2024, initial sampling at 11 locations revealed microplastics in 10 sites, with concentrations reaching up to three particles per litre. A follow-up round in February 2025, covering 14 locations, showed contamination in fewer sites, indicating that pollution levels can fluctuate over time, possibly due to seasonal or environmental factors.
Contamination Levels and Particle Characteristics
Microplastics were found circulating through fractures in hard rock formations such as granites and gneisses. The particles appeared in various forms, including fragments, filaments, and prisms. Analysis identified multiple polymer types, such as polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyethylene terephthalate (PET), which are commonly used in packaging materials and agricultural products. Most particles were smaller than 1,000 micrometres, and their linear shapes likely facilitated movement through narrow rock fractures, allowing them to infiltrate groundwater systems.
Notably, larger sample volumes revealed higher contamination levels. At locations like Ganjigunte and Mudimadugu, 20-litre samples contained significantly more particles and a wider variety of plastic types compared to one-litre samples. This suggests that smaller sampling methods may underestimate the true extent of microplastic pollution in groundwater, highlighting the need for comprehensive assessment techniques.
Sources and Health Implications
The study attributes the contamination primarily to domestic and agricultural waste, along with activities related to freshwater fishing. Common sources include plastic carry bags, multilayered packaging, irrigation pipes, mulch films, and discarded fishing gear. Researchers estimate that residents in these villages may ingest approximately 1,100 microplastic particles annually through drinking water, equating to about three particles per day.
However, the study notes that drinking water alone is not currently a major source of exposure for many villagers, as reverse osmosis systems—if properly maintained—can effectively filter out microplastics. This underscores the importance of regular maintenance and monitoring of water purification systems in rural areas to mitigate health risks.
Call for Action and Future Directions
The findings emphasize the urgent need for improved management of plastic waste in rural regions, particularly in agricultural practices and around inland water bodies. Effective waste disposal strategies and stricter regulations on plastic use could help prevent further contamination of groundwater resources. This research serves as a critical wake-up call for policymakers and communities to address plastic pollution and safeguard water quality for future generations.
