The aim of this study was to estimate the risk for caries and fluorosis in a desertification area, applying the
calcium/fluoride concentration ratio of underground water and the quality of water in a selected geographical region. This study was performed in the municipality of São João do Rio do Peixe, located in the tropical semiarid lands of Brazil. A total of 111 groundwater samples were collected.
Fluoride concentration varied from 0.11 to 9.33 mg/L. Thirty percent of all samples analyzed showed values above 1.5 mg/L, while 64 % were above the ideal limit of 0.7 mg/L. Mean
calcium concentration was 47.6 mg/L, and 14.4 % of all samples presented values above the WHO acceptable limits. The proportional value of
calcium/fluoride in water showed that only 12 % of the samples were suitable for
dental caries prevention with minimal risk for
dental fluorosis. Mapping of the
fluoride distribution indicated that approximately 2,465 people could be affected by
dental fluorosis and 1,057 people might be affected by skeletal fluorosis. It can be concluded that, in addition to
fluoride, many water parameters were not suitable for the
drinking water. Mapping out
calcium/fluoride ratio may indicate areas of water suitability for caries control, whereas the
fluoride concentration solely can indicate the areas with the risk for fluorosis. This approach can be relevant for health authorities for identifying communities where
dental caries or
dental fluorosis is prevalent.