Heavy metal contamination in Asian drinking water: a regional assessment of health risks and disability-adjusted life years (DALYs)

This study investigated heavy metal contamination in drinking water in five Asian regions (East, Southeast, South, Central, and West Asia) with an interest in inorganic arsenic (iAs), lead (Pb), mercury (Hg), cadmium (Cd), chromium (Cr) and nickel (Ni). Human exposure, risks, and the disease burdens in terms of loss of disability-adjusted life years (DALYs) were analyzed. Concentrations of heavy metals and risks in different regions were variable. Hazard index (HI), cancer risk (CR) and DALYs were used as the health metrics. The total cancer risk was highest in Southeast Asia (2.18 × 10⁻⁴) followed by South Asia (1.61 × 10⁻⁴), West Asia (1.04 × 10⁻⁴), Central Asia (8.85 × 10⁻⁵) and East Asia (3.94 × 10⁻⁵). Cancer risks exceeding 1 × 10⁻⁴ (1 in 10,000) were considered higher risk while Southeast Asia had the highest risk. In terms of population-adjusted DALY, South Asia had the highest (1.95 × 10⁵) followed by Southeast Asia (8.66 × 10⁴), East Asia (2.34 × 10⁴), West Asia (1.91 × 10⁴) and Central Asia (4.60 × 10³). Lung cancer emerged as the main outcome in all regions, accounting for 85% and 94% of cancer risks, and DALYs respectively. The findings highlight regional disparities, requiring intervention strategies in a few regions. The actions may include implementing regulations, treatment technologies and establishing monitoring systems to ensure water quality.