Weekly monitoring of the water fluoride content in a fluoridated metropolitan city--results after 1 year.

It continues to be the goal of the United States Department of Health and Human Services to fluoridate community water supplies to prevent dental caries. In Houston, Texas, where community water is assumed to contain in the range of 0.7-1.2 ppm fluoride, water samples were taken from the same source on approximately a weekly basis over a period of 52 weeks. The purpose of this study was to determine the extent of fluctuation of water fluoride concentration in these samples. Water fluoride analysis with an ion-specific electrode and millivolt meter of the data set showed a range of 0.33 to 1.00 ppm fluoride, with a mean of 0.70 ppm and a standard deviation of 0.15. This wide range of fluoride concentrations may create a risk for fluorosis in pediatric patients who are prescribed dietary fluoride supplements.