Assessment of groundwater quality in a region of endemic fluorosis in the northeast of Brazil.

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.