Fluoride concentration in public water supply related to temperature in Piracicaba - SP

Abstract

Water fluoridation of water public supply is the measurement of greater extension on dental caries prevention since it is kept at constant concentration and appropriate standards according the local temperature. The aim of this study was to verify fluoride concentration in the public water supply in Piracicaba - SP, as well as to verify possible correlation between fluoride concentration and the local temperature. Trained health agents collected montly water samples (5 ml) from 35 public preschools for about 2 years (from April/04 to February/06), totalizing 35 montly samples. Fluoride dosage was analyzed in the Biochemistry laboratory at FOP/UNICAMP with an ion analyzer connected to a fluorine electrode previously calibrated. The highest temperature ever recorded in Piracicaba was 37.5 °C and the lowest 18 °C (CIAGRI-USP). For a comparative analysis, fluoride concentrations of the hottest months (December/February) as well as of the coldest ones (June/July), by means of Mann Whitney test, at a significant level of 5%, were considered. Of the total to 630 samples, 77 (12.2%) showed fluoride concentration higher than 0.8 ppmF and 18 (2.9%) lower than 0.6 ppmF, with the majority of the samples being in excellent standards (0.6-0.8ppmF). The average in ppmF was 0.73 in the cold months and 0.71 in hot months, without significant diffe rence (p = 0.3544); however, fluoride levels varying from 0.7 to 1.2 ppmF are acceptable at temperatures between 17.8 and 21.4 °C, and 0.6 to 0.8 ppmF above 32.5 °C. Accordingly, the samples were inside the adequate bands of fluoride for the local temperature. The public water supply in Piracicaba is adequately fluoridated with excellent standards, without difference concerning temperature variation. Key words: Fluoride. Fluoride control. Temperature.