Assessing spatial distribution of heavy metal contamination in groundwater and associated human health risk in the Chittagong industrial area, Bangladesh

• Chromium, cadmium, lead, and arsenic are the key contaminants. • Over 53 % of groundwater samples exceeded the HPI limit. • Hazard Index surpassed safe limits in 67.65 % of groundwater. • Carcinogenic risks from arsenic exceeded acceptable thresholds widely. • Children face higher health risks. Heavy metal contamination of groundwater presents serious environmental and public health challenges, especially in industrial areas. This study was conducted to address the gap in understanding the health risks of heavy metal exposure in industrial regions, specifically in the Chittagong industrial zone in Bangladesh. A total of 34 groundwater samples were analyzed using indices such as the Heavy Metal Pollution Index (HPI), Heavy Metal Evaluation Index (HEI), and health risk metrics, including Hazard Quotient (HQ), Hazard Index (HI), and Cancer Risk (CR). The findings revealed widespread contamination, with 53 % of samples exceeding the HPI threshold, making the water unsuitable for drinking. Key contaminants identified include arsenic (As), chromium (Cr), cadmium (Cd), and lead (Pb), with arsenic posing the most significant risk. The study highlights the underexplored health impacts of these contaminants in the Chittagong industrial region, with arsenic levels significantly contributing to high HQ values, where 82.35 % of children samples and 61.76 % of adults samples exceeded safe limits. The HI further indicated severe non-carcinogenic risks, with 67.65 % of samples for children and 47.06 % for adults surpassing the safe threshold. Carcinogenic risk assessments found that arsenic poses the highest risk for both children and adults, with mean CR values of 2.04 × 10 –3 for children and 6.70 × 10 –3 for adults, both above the acceptable limit. The spatial distribution maps highlight key hotspots, indicating that the southern region experienced the highest levels of contamination. The present study contributes to address the significant health risks posed by heavy metal contamination, emphasizing the urgent need for mitigation measures in industrial regions to protect vulnerable populations.