Estimating Fluoride Exposure in Rural Communities: A Case Study in Western Washington

PURPOSE: Efforts to achieve national objectives for fluoridation, such as Healthy People 2010, and water quality monitoring regulations focus on public water systems and generally overlook the 15% of U.S. households with private wells. Mandated testing of public water systems and new building sites on San Juan Island, Washington revealed naturally occurring fluoride levels up to several times the EPA Maximum Contaminant Level. This study evaluated fluoride concentrations in private wells and estimated the prevalence of dental fluorosis among children to inform local stakeholders. METHODS: Primary school children were examined by a dentist for dental fluorosis, parents were surveyed about fluoride exposures, and household drinking water samples were collected to measure and map fluoride concentrations. De-identified data were analyzed using chi-square and Fisher's exact tests. RESULTS: 18.8% of examined children exhibited mild dental fluorosis, a prevalence similar to national averages. Fluoride concentrations in drinking water were 0.08 to 1.30 mg/L, below levels for health concerns, and generally (94%) below levels recommended for caries prevention. Supplemental sources of fluoride (e.g. tablets) did not account for observed fluorosis. CONCLUSIONS: Results provided community stakeholders with valuable information to support decision-making regarding fluoride levels in drinking water. Previously available information suggested potential for excessive fluoride exposure, however, these study results indicated low fluoride levels were more common. The approach used in this case study suggests a simple method of assessing the scope of fluoridation needs in communities where private water sources are common, allowing for better informed decision-making with regard to future fluoridation efforts.