Effects of High-Water Fluoride Exposure on IQ Levels in School-Age Children: A Cross-Sectional Study in Jiangsu, China

This cross-sectional research aimed to investigate the potential effects of elevated fluoride levels in drinking water on children’s intelligence quotient (IQ). A total of 721 children from rural Jiangsu, China, were included in the study and divided into two groups based on the fluoride concentration in their drinking water: a high fluoride group (HF) and a control group (CONTROL). Ion-selective electrode technology was used to assess the amount of fluoride in urine and drinking water. The Combined Raven's Test (CRT-RC2) was used to assess the IQ levels of the children. Generalized linear and multiple logistic regression models were used to examine the association between fluorine exposure and intelligence level ratings. The HF group exhibited lower average IQ scores than the CONTROL group, with a statistically significant difference among the groups ( P < 0.001). The proportion of individuals with Dull normal and below of IQ in the HF group was significantly higher than that in the CONTROL group (15.0 vs 3.1%), moreover in children with dental fluorosis (DF) was significantly higher than that in children without it (21.8 vs 4.4%), in children with excessive urinary fluoride (UF) was significantly higher than that in children with normal UF (16.5 vs 1.7%); these distributions were significantly different ( P < 0.001, P = 0.048, P < 0.001, respectively). Furthermore, the risk of below normal IQ in children from the HF group was significantly elevated compared to CONTROL children with a normal intelligence quotient, with an adjusted OR of 6.81 (95% confidence interval [CI]: 3.20, 14.48). Urinary fluoride (UF) was inversely linked with IQ scores, with an adjusted coefficient ( β ) of −4.08 (95% CI −3.04, −1.32). The coefficient of UF in the HF group was statistically different from that in the CONTROL group ( P < 0.001). Excessive exposure to fluorine has severe negative effects on the intellectual development of children. It is necessary to monitor children's urinary fluoride levels and investigate other sources of fluoride intake.