Human and ecological health risks from heavy metal contamination in groundwater aquifers

Landfills are the most commonly used Municipal Solid Waste (MSW) disposal method in the world. However, poorly engineered open landfill sites pose significant environmental threats, particularly groundwater contamination from leachate infiltration. In alignment with Sustainable Development Goals (SDGs), SDG 3- Good Health and well-being, Goal 6- Clean water and sanitation (SDG#5), this study conducts a comprehensive hydro-chemical assessment of twenty-four (24) groundwater samples extracted across four georeferenced zones surrounding Sialkot landfill sites, Punjab, Pakistan. A total of 22 physicochemical parameters were analyzed. Findings reveal non-compliance with Punjab Environmental Quality Standards (PEQs) and WHO drinking water guidelines. Elevated heavy metal concentrations- Chromium (Cr), Zinc (Zn), Lead (Pb), and Nickel (Ni) exceeded safe thresholds in all zones, while Cyanide (CN), Manganese (Mn), and Copper (Cu) remained within limits. Metal concentration order was observed as Mg > Zn > Cu > Fe > Pb > Cr > Mn > Ni > CN. Geo-accumulation factor and ecological risk index flagged Zone 1 as critically impacted, particularly by Cr and Ni. Fe levels remained constantly lower than 1 mgL^- 1. The health risk assessment using the US EPA probabilistic model showed that the risk of Cr and Ni-related chronic diseases is higher in both adults and children through ingestion and dermal absorption.