Teores residuais de fluoretos e coeficiente de inteligência de crianças com fluorose dentária em áreas rurais da Paraíba

Abstract

Mental impairment from fluoride ingestion has been reported in the literature, which has led to controversy regarding the safety of water fluoridation. However, the potential neurotoxicity associated with fluoride ingestion remains uncertain. The aim of this study was to determine the residual fluoride levels naturally occurring in drinking water and the intelligence quotient (IQ) of children with fluorosis in rural areas of Paraíba. To achieve this, three studies were conducted. Study 1: A scoping review of articles indexed in PubMed, Scopus, Lilacs and the Cochrane Library was conducted. The key question was: "What evidence is there for the association between fluoride exposure and low IQ?" The study included articles published between 2019 and 2024 and the search strategy included the keywords "fluorosis" OR "fluoride" AND "intelligence", “Fluorosis” OR “Fluoride” AND “Intelligence” OR “IQ”, “Fluorosis” OR “Fluoride” AND “Intelligence Quotient”. The majority of articles suggest that fluoride affects cognitive development. However, the limitations of the studies included in this review, particularly with regard to the risk of residual confounding, lead to uncertainties about the causal nature of such an association and the exact exposure limits. Study 2: To map residual fluoride levels, water samples were collected from 24 sites in the rural area of Poço de José de Moura (PB). Samples were analyzed in triplicate using a specific fluoride electrode and TISAB II as a buffer. All community samples had residual fluoride levels ranging from 0.04 ± 0.00 mgF/L to 6.56 ± 2.81 mgF/L. Therefore, most sites had residual concentrations of fluoride, with some wells showing elevated levels. Study 3: As a cross-sectional study, a nested case-control study was conducted with a representative sample of 176 school children of both sexes aged 6 to 11 years with permanent residence in rural areas in three municipalities of the Cajazeiras microregion. Paraíba, Brazil. The case group (children with higher IQ) and the control group (children with lower IQ) were randomly selected according to age and gender in a ratio of 1:1 (88 cases to 88 controls). The CPM-Raven test was used to estimate IQ. Fluorosis and dental caries were clinically observed after tooth brushing and drying using CPO-D/ceo-d and TF indices, respectively. Data analysis included descriptive analysis, Pearson chi-square test, and unadjusted and adjusted conditional logistic regression analyzes [p≤0.05; 95% confidence interval (CI 95%)]. Of the total children with lower IQ evaluated, 56.3% (p=0.003) had a monthly family income of up to a minimum wage. There was no significant association between the independent variables: dental caries, fluorosis and water fluoride content with IQ (p>0.05). Therefore, monthly family income was associated with lower intelligence levels, suggesting that low IQ is related to social determinants.