Microplastic contamination in urban groundwater: Risk assessment, citizen perception and policy imperatives - a case study of Kozhikode City, Kerala State, India.

Microplastics (MPs) contamination in urban groundwater is an emerging environmental and public health threat, particularly in regions relying on open wells for drinking water. This study examines the occurrence, characteristics, ecological risks and sources of MP contamination across 120 open wells in Kozhikode Municipal Corporation, Kerala, India. MPs were detected in 73.33 % of samples, with concentrations ranging from 24 to 1889 particles/L (average: 103.73 ± 2.28 particles/L). Polypropylene (75.66 %) was the dominant polymer, followed by high-density polyethylene (HDPE) (9.56 %) and low-density polyethylene (LDPE) (7.7 %). Particle size analysis showed a predominance of 30-100 μm particles, with significant fractions under 30 μm, raising concerns about biological uptake and health risks. Ecological risk assessment using the polymer hazard index (PHI) and pollution load index (PLI) identified polyvinyl chloride (PVC) as the most hazardous polymer (PHI: 10,001), with several urban hotspots exhibiting high pollution loads. Positive matrix factorization (PMF) results, supported by field observations, identified three major source categories: beverage and packaging waste (e.g., bottles, wrappers) linked to HDPE and polystyrene (PS); household and agricultural sources (e.g., domestic waste, well covers, nets) associated with polyethylene terephthalate (PET) and PVC; and medical and industrial inputs (e.g., personal care products, textile fibers) corresponding to polyvinylpyrrolidone (PVP) and polyethylene-co-polypropylene (PE-co-PP), highlighting diverse contamination pathways. A household survey of 450 respondents revealed a significant knowledge gap, with 75.8 % unaware of microplastics in drinking water. However, 85.8 % expressed a strong willingness to adopt sustainable alternatives, including coir or jute-based well covers and non-polymeric water extraction tools. These findings underscore the urgent need for integrated policy interventions, community education, and sustainable infrastructure improvements to safeguard groundwater quality in urban settings.