Qualidade da fluoretação de águas de abastecimento público no nordeste do estado de São Paulo (Brasil):avaliação e investigação de fatores relacionados

Introduction: Fluoridation of public water supply is a population-based strategy for preventing dental caries by adjusting the concentration of fluoride in the water. Objective: To evaluate the quality of water fluoridation in 90 municipalities in the northeastern region of the state of São Paulo (Brazil); to verify whether the COVID-19 pandemic influenced this quality; to investigate the relationship between the quality of fluoridation in municipalities with demographic data and water physicochemical and microbiological data. Method: 14,307 water samples from the Water Surveillance Program for Human Consumption were analyzed in 4 periods: 05/04/2015-04/27/2016; 03/18/2019-03/17/2020; 07/01/2020-06/30/2021; 03/01/2023-02/28/2024. Fluoride was determined by ion chromatography or potentiometry. To quality assessment, the Fluoridation Indicator (IFLU) was used, defined as the percentage of samples with adequate fluoride concentration. Results: There were no significant differences between the IFLUs of the municipalities in the 4 periods; 29 municipalities exhibited satisfactory fluoridation, including 24 where the Basic Sanitation Company of the State of São Paulo (Sabesp) operates, corresponding to 24.8% of the population of the region; 66 municipalities where Sabesp does not operate were studied by multivariate analysis: the IFLUs showed significant correlations with chlorination levels, positive microbiological results, population, Municipal Human Development Index (MHDI), education and wealth. Conclusions: Adequately fluoridated water is supplied to only 24.8% of the region’s population; the COVID-19 pandemic did not affect the quality of fluoridation; inadequate fluoridation of water in municipalities with smaller populations where Sabesp does not operate is associated with lower richness, schooling and MHDI, low levels of chlorination and a higher frequency of positive microbiological results.