Seasonal evaluation of groundwater quality and health risks associated with chromium in the ranipet industrial region of Tamil Nadu, India, employing the water quality index and age-specific risk assessment

Abstract

Assessing groundwater quality is crucial in industrial areas where human activity may compromise drinking water safety. This study evaluated seasonal groundwater quality and chromium (Cr)-related health hazards in the Ranipet industrial area, Tamil Nadu, India, using the Water Quality Index (WQI) and age-specific health risk assessment, based on 206 groundwater samples collected seasonally and analysed for physicochemical parameters and heavy metal concentrations. Pre-monsoon, samples were classified as 1% excellent, 32.04% good, 42.72% poor, 13.59% very poor, and 10.68% unsuitable for drinking. Postmonsoon, this shifted to 0.97% excellent, 8.74% good, 17.48% poor, 33.01% very poor, and 39.81% unsuitable. Mean chromium concentrations rose from 0.0085 to 0.1824 mg/L between pre- and postmonsoon periods, with a maximum of 2.465 mg/L recorded post-monsoon. Health-risk assessments mean HQ for children rising from 0.166 to 3.564 and for adults from 0.120 to 2.583, showing a rising noncarcinogenic risk post-monsoon. Mean ILCR increased from 3.0 × 10⁻6 to 6.6 × 10⁻5 for children and 7.0 × 10⁻6 to 1.59 × 10⁻4 for adults. Samples exceeding the ILCR threshold (>1 × 10⁻4) increased from 0.97% to 29.13% of children and 2.91% to 46.60% of adults. The increase in Cr concentration coincided with WQI deterioration, with mean WQI increasing from 65.99 to 100.46 and very poor/unsuitable samples increasing from 24.27% to 72.82%. These results show a marked seasonal decline in groundwater quality and an increase in Cr-related health risks post-monsoon. The combined WQI and health-risk framework shows groundwater risk hotspots and underscores the need for continuous monitoring in the Ranipet industrial region.