Serum Fluoride Level and Children's Intelligence Quotient in Two Villages in China
Background: Animal studies show that brain fluoride levels increase with increasing exposure to fluoride. Human studies have indicated an association between high levels of drinking-water fluoride and lower intelligence. Data on the association between serum fluoride and children’s intelligence quotient (IQ) are limited.
Objective: This study was conducted to assess the relationship between serum fluoride and children’s IQ.
Methods: We collected blood samples from 512 children aged 8-13 years from two villages (Wamiao and Xinhuai) in China. We also used minitype fluoride ion selective electrode and Combined Raven’s Test for Rural China (CRT-RC) to measure serum fluoride and children’s IQ.
Results: In Wamiao, the mean (± SD) concentration of fluoride in serum was 0.081± 0.019 mg/L, and average children’s IQ was 92.02 ± 13.00; in Xinhuai, fluoride concentration was 0.041 ± 0.009 mg/L and average IQ was 100.41 ± 13.21. The regression coefficients between serum fluoride and children’s IQ were –0.163 (p = 0.015) in Wiamiao, and 0.054 (p = 0.362) in Xinhuai. Serum fluoride levels were negatively associated with IQ after adjusted for age and sex, the ORs for IQ < 80 across groups with serum fluoride measuring < 0.05, 0.05–0.08, > 0.08 mg/L were 1, 2.22 (95% confidence interval: 1.42–3.47), and 2.48 (95% confidence interval: 1.85–3.32) (p for trend < 0.001) respectively. IQ was not related to family income and parent’s education level. There was a significant positive relation between serum fluoride and drinking-water fluoride.
Conclusions: The results indicated that fluoride in drinking water was highly correlated with serum fluoride, and higher fluoride exposure may affect intelligence among children.
The Center for Disease Control (CDC) web site lists sodium fluorosilicate as a water additive in the United States.
In the 2010 Crop Protection Handbook, one of the primary references for pesticides, sodium fluoroacetate is listed as a rodenticide and sodium fluorosilicate is listed as an insecticide.
*PARTIAL* List of insecticides that contain Sodium Fluorosilicate include Terro Roach Killer, Ortho Earwig Bait, Roach-O and Pearson's Roach Poison.