Endemic Fluorosis in San Luis Potosi, Mexico Iii. Screening for Fluoride Exposure with a Geographic Information System

A Geographic Information System (GIS) coupled with environmental and health data was used for the study of human exposure to fluoride in the city of San Luis Potosi (SLP). The city was divided into four different risk areas. These areas were categorized according to fluoride levels in tap water, fluoride concentrations in well water and dental fluorosis prevalence in children. Fluoride levels in tap water apparently explain the prevalence of dental fluorosis. However, in SLP tap water is not the only source of fluoride. This conclusion was reached by finding that almost one third of the children studied in area 1 were categorized as having moderate or severe dental fluorosis. Area 1 has a mean fluoride level of only 0.9 ppm in tap water. As a whole, this work is an example of how the use of a GIS can be useful for the identification of risk areas in terms of human exposure to fluoride. It also gave further evidence for the presence in SLP of sources of fluoride different from tap water.