Fluoride 2003; 36(2): 84-94

Effect of fluoride in drinking water on children's intelligence.

Q Xiang (a), Y Liang (a), L Chen (b), C Wang (b), B Chen (a), X Chen (b), M Zhou (c)

(a) Department of Occupational Health, School of Public Health, Fudan University (Formerly Shanghai Medical University), Shanghai, 200032, China.
(b) Center for Disease Control and Prevention, Jiangsu Province, China.
(c) Center for Disease Control and Prevention, Sihong County, Jiangsu Province, China.

SUMMARY: The Intelligence Quotient (IQ) was measured in 512 children, aged 8-13 years, sliving in two villages in Sihong County, Jiangsu Province, China, differing in the level of fluoride in their drinking water. In the high-fluoride village of Wamiao (water-fluoride: 2.47+0.79 mg/L; range: 0.57-4.50 mg/L), the mean IQ of 222 children was significantly lower (92.02=13.00; range: 54-126) than in the low-fluoride village of Xinhuai (water fluoride: 0.36+0.15 mg/L; range: 0.18-0.76 mg/L), where the mean IQ of 290 children was higher (100.41+13.21; range 60-128). The children's IQs were not related to urinary iodine, family income, or parent's education level. Higher drinking water fluoride levels were significantly associated with higher rates of mental retardation (IQ <70) and borderline intelligence (IQ 70-79). The Benchmark Concentration (BMC) for the concentration-response relationship between IQ confidence limit (BMCL) of the BMC was 1.85 mg/L. Taking dental fluorosis and other sources of dietary fluoride into account, the reference value concentration (RfC) for fluoride was calculated to be 0.925 mg/L, which is very close to the current national Chinese standard of <1.0 mg/L. In endemic fluorosis areas, drinking water fluoride levels greater than 1.0 mg/L may adversely affect the development of children's intelligence.

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