Fluoride hot spots identified in groundwater aquifers

Abstract

Researchers from the Swiss Federal Institute of Aquatic Science and Technology (Eawag) have created a machine learning algorithm that can predict where groundwater contains unsafe levels of naturally occurring fluoride. Fluoride, which is abundant in Earth’s crust, enters groundwater through the weathering of minerals. Using the model, the scientists calculated that about 180 million people worldwide are at risk of being exposed to fluoride concentrations above the World Health Organization’s recommended guideline of 1.5 mg/L ( Nat. Commun. 2022, DOI: 10.1038/s41467-022-31940-x ). Although scientists have shown that fluoride concentrations within the range of 0.5–1 mg/L in drinking water are safe and can help prevent tooth decay , consuming levels above the WHO’s recommended limit can result in dental fluorosis , which causes brown staining of the teeth. Fluoride consumption above 6 mg/day can also cause skeletal fluorosis, a disabling disease characterized by bone deformities. The researchers also combined the fluoride