Análise do teor de flúor nas águas de abastecimento público do Ceará

Abstract

The verification of fluorine in water consumption is also necessary in location where there era no public water fluoridation systems, due to the fact that fluorine can be present in water resources. The objectives of this research were: to verify fluorine concentration in public water supply at Ceará, to identify a possible difference in fluorine concentration of two samples of water collected in the city, to know the process of water fluoridation in cities and to compare the fluorine concentration informed by the control operator oh water treatment with the results of this study in the cities that accomplished public water fluoridation. This research was accomplished in two phases. In the first phase, two samples of water from each city were collected and in the second phase, questionnaires were sent to the operator of the water treatment plant that realized fluoridation. Out of 184 cities of Ceará, 173 had it water analyzes, completing 94% of total universe. For each city, two samples of water were analyzed: one of the treatment plant and another from a tap located in downtown. The analyzes were realized at the Central Laboratory of Public Health of Fortaleza, using the electronic method, though a potentiometer (Mettler Toledo DL50 Graphix) and a specific electrode for fluoride ions (Mettler Toledo DX 219 F-) those methods are extolled by the “ Standard Methods of the Examination of Water and Wastewater”. The questionnaires to the operators were sent by the post office. The questions were about the process of water fluoridation, such as: year of implementation, institution that realized it, type-of salt used in the process, frequency, control operational method, among others. All of 28 cities that accomplished water fluoridation in the State of Ceará participated in the second phase of the research. To compare statistically the two samples collected in the 173 cities, Wilcoxon test was used and to compare fluorine concentrations informed by the operator and those concentrations found in this research, Student test was used. The results showed that there are no significative difference between the samples of water collected at the water treatment plant and those collected from a tap in downtown (p>0,05). Out of 173 cities, 160 presented their water collected in downtown with fluorine concentration below 0,6ppm. Only 12 cities showed fluorine concentration between 0,6 and 0,8ppm, and one city presented concentration above 0,8ppm of fluorine. About water fluoridation process, 60,7% of the cities are operated by the Sewer and Water Company of Ceará, the salt used for fluoridation in 100,0% of the cities is fluossilicate of sodium, 67,9% of the cities use the colorimeter method to analyze the fluorine concentrations and the frequency of control is every two hours in 71,4% of the cities. The fluorine concentration found in the water treatment plant exhibited significative difference comparing to the concentrations informed by the operational control workers (p< 0,05). Based on these results, it can be concluded that most of the cities of Ceará (86,9%), the population drink water with fluorine concentration below 0,6ppm