Global inequalities in non-carcinogenic health risks associated with drinking arsenic-contaminated groundwater

Groundwater arsenic contamination poses a widespread yet insufficiently quantified threat to global drinking water safety and public health. In this study, machine learning-based groundwater arsenic predictions were integrated with a human health risk assessment (HHRA) framework to assess global non-carcinogenic risks from chronic ingestion of arsenic-contaminated groundwater. The hazard quotient (HQ), a measure of non-carcinogenic risk, was estimated and populations potentially exposed to HQ > 1 were identified. High-risk regions were concentrated in Southern Asia, Eastern Asia, and Central America. Bangladesh, Pakistan and Argentina are among the most severely affected countries. Approximately 350.6 million individuals (95% CI: 347.1-354.1 million) face elevated risks (HQ > 1), with 81.4% concentrated in Southern Asia. This health burden is unevenly distributed across demographic population groups, with higher estimated risks for women under sex-specific HHRA parameterization, rural communities reliant on untreated groundwater, and populations in low- to medium- human development index (HDI) countries. Using SHapley Additive exPlanations (SHAP) analysis, chronic arsenic exposure was identified as a potential environmental risk indicator for cardiovascular disease burden. These findings reveal stark global inequities in health risks associated with drinking arsenic-contaminated groundwater and underscore the urgent need for targeted risk mitigation, safe water provision, and equity-sensitive policies to achieve sustainable development.