Spatiotemporal distribution, health risk assessment, and preventable disease burden of dental and skeletal fluorosis via defluoridation scenarios in Fars Province, Iran.

Fluoride contamination in groundwater poses a persistent public health challenge in arid regions, where elevated concentrations lead to dental and skeletal fluorosis. Current defluoridation policy evaluations have overlooked the population health benefits of interventions, the variability in technology performance, and the direct link between treatment efficacy and health outcomes. Hence, this study employed a comprehensive spatiotemporal probabilistic health risk assessment with disease burden estimation. It integrated disability-adjusted life years (DALY)-based intervention policy modeling and kernel density estimation to create a strategic framework. In this method, intervention scenarios were stochastically modeled using literature-derived fluoride-removal efficiency ranges. Groundwater samples (n = 7,722) were collected from counties of Fars Province, Iran, during 2015-2020. Hierarchical clustering delineated four fluoride risk zones: low (LFZ), moderate (MFZ), high (HFZ), and extreme (XFZ). The highest proportions of exceedance rates of hazard quotient (%HQ > 1) were concentrated in southern and southwestern zones across all age groups. Dental fluorosis was the dominant health outcome, with XFZ encompassing a cumulative burden of 669.14 (95% UI: 478.54-859.74) DALYs and normalized rates up to 1888.55 (1461.59-2315.52) per 100,000. Skeletal fluorosis contributed to lower burdens in all clusters, yet the burden was as high as 132.95 (115.23-150.67), with a rate of 458.72 (442.42-475.01) per 100,000 in XFZ. The probabilistic evaluation of nine defluoridation policies revealed reverse osmosis and ion exchange/precipitation as the most effective interventions, achieving > 98% and 96% reductions in DALYs, respectively. These methods significantly outperformed alternatives like phytoremediation (60-90% reduction) and nutritional interventions (< 50% reduction). For all policies, the percentage reduction in DALYs was the same for dental and skeletal outcomes. The proposed framework in this research supports prioritization of defluoridation interventions and demonstrates how probabilistic health-risk modeling can inform adaptive water governance and resource allocation in fluorosis-endemic regions.