Assessment of lead contamination in drinking water in zone I and zone III of Islamabad, Pakistan

This study assesses the level of Pb contamination in sources of drinking water from Zone I and Zone III of Islamabad, Pakistan, to help identify sources of contamination and quantify associated health risks while providing actionable insights. Altogether, 169 water samples were collected from springs and bore water with depths ranging from 17 to 300 feet. The focus lies on the comparison of anthropogenic sources (bore water of Zone III) along with the pipe types (PVC and metal) with the natural source of water (springs of Zone III) to identify the reason for contamination. Pb concentrations were determined using atomic absorption spectrophotometry, with health risk assessments done on HQ and lifetime cancer risk indices. Results showed that Pb levels in Zone III, spring waters were below detection limits at < 0.01 mg/L, which suggests less natural Pb contamination. Zone I from metal pipes showed a median Pb value above 0.1 mg/L, which is beyond WHO’s permissible limit of 0.01 mg/L. Regression analysis revealed that pipe material, water chemistry, and stagnation time were the significant contributors to Pb contamination. Spatial distribution maps indicated that high-risk sectors were H9, G6, and I10 with Pb concentrations of 0.307 mg/L. Health risk assessments indicated high non-carcinogenic and carcinogenic risks, particularly for children in low-income sectors. The PCA highlighted the leading role of anthropogenic sources, specifically corrosion in metal pipes, in driving Pb contamination. This study calls for policy intervention, upgrades and alternatives for pipes, and targeted risk mitigation strategies to promote public health, particularly that of vulnerable populations exposed in high-risk areas.