I.Q. - Adverse Effects
Sodium fluoride
CAS No. 7681-49-4

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• Note: The following is a limited selection of abstracts from 1994 to present.
• Due to length, we present this as a separate section
• When time allows more information will be added.

Full report available at: http://www.fluoride-journal.com/00-33-2/332-74.pdf

Fluoride 2000; 33(2): 74-78

Effect of high fluoride water on intelligence of children

Y Lu (a), ZR Sun (a), LN Wu (a), X Wang, (a), W Lu (a), SS Liu (b)

(a) Dr Yan Lu, Department of Environmental Health, Tianjin Medical University, Tianjin, China. Emai: yan_lv@hotmail.com.
(b) Tianjin Xiqing District Anti-Epidemic Station, Tianjin, China.

SUMMARY: The Intelligence Quotient (IQ) was measured in 118 children, aged 10-12 years, who were life-long residents in two villages of similar population size and social, educational and economic background but differing in the level of fluoride in drinking water. The children in the high-fluoride area (drinking water fluoride 3.15 ± 0.61 mg/L [ppm]) (mean ± S.D.) had higher urinary fluoride levels (4.99 ± 2.57 mg/L) than the children in the low-fluoride area (drinking water fluoride 0.37 ± 0.04 mg/L) (urinary fluoride 1.43 ± 0.64 mg/L). The IQ of the 60 children in the high-fluoride area was significantly lower, mean 92.27 ± 20.45, than that of the 58 children in the low-fluoride area, mean 103.05 ± 13.86. More children in the high-fluoride area, 21.6%, were in the retardation (<70) or borderline (70-79) categories of IQ than children in the low fluoride area, 3.4%. An inverse relationship was also present between IQ and the urinary fluoride level. Exposure of children to high levels of fluoride may therefore carry the risk of impaired development of intelligence.

Fluoride 1996; 29(4):190-192

Effect of a High Fluoride Water Supply on Children's Intelligence

Zhao LB, Liang GH, Zhang DN, Wu XR Lu-Liang

Public Health Bureau, Shanxi 033000, China.

In Shanxi Province, China, children living in the endemic fluoride village of Sima (water supply F = 4.12 mg/L) located near Xiaoyi City had average IQ (97.69) significantly lower (p < 0.02) than children living to the north in the nonendemic village of Xinghua (F = 0.91 mg/L; average IQ = 105.21). These differences were not associated with gender, but the IQ scores were directly related to educational level of the parents.

Fluoride 1995; 28(4):189-192

Effect of fluoride exposure on intelligence in children

Li XS (a), Zhi JL (b), Gao RO (c)

(a) Guizhou Provincial Sanitary and Anti-epidemic Station, Guiyang City, 550001, China
(b) Anshun Prefecture Sanitary and Anti-Epidemic Station
(c) Zhijin County Sanitary and Anti-Epidemic Station

Summary: The intelligence was measured of 907 children aged 8-13 years living in areas which differed in the amount of fluoride present in the environment. The Intelligence Quotient (IG) of children living in areas with a medium or severe prevalence of fluorosis was lower than that of children living in areas with only slight fluorosis or no fluorosis. The development of intelligence appered to be adversely affected by fluoride in the areas with a medium or severe prevelence of fluorosis but to a minor extent only in areas with only a slight prevalence of fluorosis. A high fluoride intake was associated with a lower inteligence. No correlation was found between age and intelligence in the areas with a medium and severe prevalence of fluorosis. The effect of exposure to a high level of fluoride on intelligence may occur at an early stage of development of the embryo and infant when the differentiation of brain nerve cells is occurring and development is most rapid.


Hua Xi Yi Ke Da Xue Xue Bao 1994 Jun;25(2):188-91

[Effect of excessive fluoride intake on mental work capacity of children and a preliminary study of its mechanism]

[Article in Chinese]

Li Y, Li X, Wei S.

We made an investigation in 157 children, aged 12-13, born and grew up in a coal burning pattern endemic fluorosis area and an experiment on excessive fluoride intake in rat. The results showed:
(1) Excessive fluoride intake since early childhood would reduce mental work capacity (MWC) and hair zinc content:
(2) The effect on zinc metabolism was a mechanism of influence on MWC by excessive fluoride intake;
(3) Excessive fluoride intake decreased 5-hydroxy indole acetic acid and increased norepinephrine in rat brain; whether this is also a mechanism of the influence on MWC awaits confirmation.

PMID: 7528715 [PubMed - indexed for MEDLINE]

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