1996, pp 57-58
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FLUORIDE 29 (2) 1996, pp 57-58 |
International Society for Fluoride Research | Table of Contents |
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Fluoride Vol. 29 No. 2 1996 EDITORIAL
NEUROTOXICITY OF FLUORIDE
The August 1995 issue of this journal contained an abstract (pages 151-152) of an interesting paper by Dr Phyllis Mullenix and her collaborators.1 They recorded behavioral changes in rats after ingestion of fluoride, and found that the severity of the effect on behavior increased directly with plasma fluoride levels and fluoride concentration in specific brain regions. A reading of the full paper is well worthwhile. In their Introduction, after referring to the increase in dental fluorosis in humans after decades of water fluoridation, the authors comment:
"One concern that has not been fully investigated is the link between fluoride and effects an the central nervous system (CNS).... Many years of ubiquitous fluoride exposure have not resulted in obvious CNS problems such as seizures, lethargy, salivation, tremors, paralysis, or sensory deficits. Still unexplored, however, is the possibility that fluoride exposure is linked with subtle brain dysfunction."
The carefully designed animal experiment which they report revealed subtle but very real changes in behavior patterns following fluoride ingestion: hyperactivity after prenatal exposure, and cognitive deficits after weanling and adult exposure. Fluoride accumulation in important regions of the rat brain, especially the hippocampus, was found to increase as the drinking water fluoride levels increased. These effects, and the sex differences observed, corresponded to those observed in other studies of hippocampal brain damage.
The authors point out that the plasma fluoride levels recorded in the rats were the same as those sometimes recorded in humans - for example, in children one hour after receiving topical fluoride treatment of their teeth. In their conclusion calling for further rat and human studies they state:
"Experience with other developmental neurotoxicants prompt expectations that changes in behavioral function will be comparable across species, especially humans and rats. Of course behaviors per se do not extrapolate, but a generic behavioral pattern disruption as found in this rat study can be indicative of a potential for motor dysfunction, IQ deficits and/or learning disabilities in humans."
The authors draw attention to reports from Chinese investigators that high levels of fluoride in drinking water (3-11 ppm) affect the central nervous system directly without first causing the physical deformations of skeletal fluorosis.2-4 Readers of Fluoride will recall the recent (November 1995) research report from China indicating adverse neurological effects on the brain from fluoride exposure.5 This work also suggested that children with dental fluorosis are at greater risk of decreased mental acuity. One can only wonder whether the effects of fluoridated water might extend beyond the appearance of the teeth and include neurotoxicity among children afflicted with dental fluorosis.
Some of our readers may recall also pertinent early clinical findings reported by our founding editor, Dr G L Waldbott, of which Dr Mullenix and her co-workers do not appear to have been aware. These involved a wide range of reversible toxic effects of fluoridated drinking water, including diminished mental acuity and impairment of memory.6-8 In a separate report, Dr Waldbott even gave an account, supported by laboratory data, of a case of tetaniform convulsions induced by drinking fluoridated drinking water.9 For decades proponents of water fluoridation have questioned the validity of these reports without, however, offering objective evidence to refute them. But in the light of the human research in China and now the animal research in the United States, these clinical observations by Dr Waldbott on the neurotoxicity of fluoride in drinking water clearly deserve greater attention and credence.
AWB and JC
References
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XXIst WORLD CONFERENCE of the INTERNATIONAL SOCIETY FOR FLUORIDE RESEARCH in association with the HUNGARIAN SOCIETY FOR FLUORIDE RESEARCH, will be held in BUDAPEST, HUNGARY. AUGUST 25 - 28, 1996.
Three-day SCIENTIFIC PROGRAM (26th, 27th, 28th) includes discussions on effects of fluoride on humans, animals, plants, and the environment. All proceedings in English.
REGISTRATION FEE: Delegate US$300, accompanying guest US$150 (includes lunches and coffee breaks).
VENUE: Aquincum Hotel.
ACCOMMODATION (at Hotel) for 4 nights (25th, 26th, 27th, 28th): single room US$149 per night double room US$97 each person per night. Book direct with hotel:
H-1036 Budapest, Árpád fejedelem
útja 94, Hungary. (Phone 361 250 3360. Fax 361 250 4672).
SOCIAL: Farewell Banquet US$100. Conference days will be free after 2 pm, with special programs planned. Daily and Post-Conference
TOURS at special rates have been arranged. For costs and other information, direct enquiries to: Dr Miklós Bély, Department of Morphology, National Institute of Rheumatology, PO Box 54, H-1525 Budapest 114, Hungary (Phone 361 212 2689. Fax 361 212 2676).
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FLUORIDE 29 (2) 1996, pp 57-58 |
International Society for Fluoride Research |
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