Fluoride in Drinking Water A Scientific Review of EPA's Standards (2006) / Chapter Skim
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7 Neurotoxicity and Neurobehavioral Effects
7 Neurotoxicity and Neurobehavioral Effects
Pages 205-223
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From page 205... ...
This study compared the intelligence of 512 children (ages 8-13) living in two villages with different fluoride concentrations in the water.
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From page 206... ...
Urinary fluoride concentrations were measured at 4.99 ± 2.57 mg/L in the high-fluoride area and 1.43 ± 0.64 mg/L in the low-fluoride area. IQ measurements using the Chinese Combined Raven's Test, Copyright 2 (see Wang and Qian 1989)
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NEUROTOXICITY AND NEUROBEHAVIORAL EFFECTS 20 FIGURE 7-1 Distribution of IQ scores from females in Wamiao and Xinuai. SOURCE: data from Xiang et al.
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From page 208... ...
Urinary fluoride concentrations were found to be inversely correlated with IQ, as measured by the China Rui Wen Scale for Rural Areas, and were monotonically related to the degree of enamel fluorosis. Studies based on fluoride exposure from the inhalation of smoke from coal fires are difficult to interpret because of exposure to many other contaminants in smoke.
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NEUROTOXICITY AND NEUROBEHAVIORAL EFFECTS 20 nation of exposure to fluoride and returned when exposure was reinstated. In some instances, when the fluoride was given in water, this procedure was repeated several times under conditions in which neither the patient nor the provider of the fluoride knew whether the water contained fluoride.
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From page 210... ...
210 FLUORIDE IN DRINKING WATER concluded that there is no "credible evidence" that water fluoridation has any quantifiable effect on the solubility, bioavailability, or bioaccumulation of any form of lead. Another issue that has been raised about differential effects of silicofluorides comes from the dissertation of Westendorf (1975)
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From page 211... ...
1994) , a significant decrease in cognitive abilities was found when their drinking water contained calcium, aluminum, and fluorine.
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From page 212... ...
. animal studies Behavioral Changes Studies of NaF One of the most frequently cited and much discussed studies reporting a link between fluoride and behavior is by Mullenix et al.
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Fluoride concentrations in the brain were not measured in this group. In experiment 2, high mortality was observed in the highest treatment group (175 mg/L)
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From page 214... ...
Plasma fluoride concentrations were increased in males and females. Testing of fluoride concentrations in the brain found increased concentrations in the medulla of both sexes and in the hippocampal region of females.
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In both treatment groups, food intake and body weight gain were reduced in
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There was a dose-related decrease in cholinesterase in the blood but not in the brain. Similar effects on motor activity have been observed in other studies in which rats were treated with NaF at 500 mg/L in drinking water.
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Toenails and teeth indicated a condition reflecting a hypermelanosis. Body weights, however, did not vary among the groups.
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218 FLUORIDE IN DRINKING WATER hemisphere. These observations are similar to previous findings reported in the brains of cats after intracerebroventricular administration of aluminum chloride (Crapper and Dalton 1973)
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In fact, adding substantial amounts of aluminum inhibited it. As in several types of experiment, it is the low aluminum fluoride concentrations that produce the greatest biochemical or physiological effects.
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From page 220... ...
These studies were conducted in different areas of China, where fluoride concentrations ranged from 2.5 to 4 mg/L. Comparisons were made between the IQs of children from those populations with children exposed to lower concentration of fluoride ranging from 0.4 to 1 mg/L.
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From page 221... ...
However, the observed changes were not striking in magnitude and could have been due to alterations in hormonal or peptide activity. Animal studies to date have used conventional methodologies to measure learning and memory abilities or species-typical behaviors in novel locations.
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222 FLUORIDE IN DRINKING WATER has been found to be reduced in regions of the brain thought to be most important for mental stability and for adequate retrieval of memories. It appears that many of fluoride's effects, and those of the aluminofluoride complexes are mediated by activation of Gp, a protein of the G family.
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From page 223... ...
. · Additional animal studies designed to evaluate reasoning are needed.
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