ASSESSMENT OF THE EXPOSURE TO FLUORIDE FROM DRINKING WATER IN DURANGO, MEXICO, USING A GEOGRAPHIC INFORMATION SYSTEM

SUMMARY: A Geographic Information System (GIS) coupled with environmental data was used for the study of endemic fluorosis in the city of Durango, Mexico. The city was divided into four different risk areas. These areas were categorized according to fluoride levels in tap water. Mean fluoride levels ranged from 1.54 mg/L in area 1 to 4.70 mg/L in area 4. A level of 5.67 mg/L, the highest fluoride concentration in Durango, was found in area 4. Almost 95% of the 306,652 inhabitants living in this city were exposed to fluoride levels higher than 2.0 mg/L. Exposure doses to fluoride were calculated for all the areas. For example, the maximum estimated exposure doses were 1.86 mg/kg/day for infants, 0.28 mg/kg/day for children and 0.16 mg/kg/day for adults. Taking into account the minimal risk level of 0.05 mg/kg/day calculated by the Agency for Toxic Substances and Disease Registry, a health risk for the city of Durango became evident.