FLUORIDE 30 (2)  1997, p 110	International Society for Fluoride Research	Table of Contents

110 BOOK REVIEW. Fluoride Vol. 30 No. 2 1997

THE METABOLISM AND TOXICITY OF FLUORIDE

by Gary M Whitford
(2nd, revised edition, Karger, Basel 1996)

Reviewed by Bruce Spittle^a and John Colquhoun^b

This second edition covers fluoride metabolism thoroughly, in 104 pages, but appears to be uncritical in accepting the beneficial effects attributed to fluoride, and to be unbalanced in its coverage of chronic toxicity to which five pages are given. Other sections refer to dental caries and fluoride in the oral environment (five pages), and acute fluoride toxicity (25 pages).

The section dealing with fluoride absorption from the gastrointestinal tract has been revised to include the absorption of monofluorophosphate, and the effect of dietary calcium and endogenous fluoride concentrations, which can reduce fluoride absorption. Information is given on the effect of plasma fluoride levels on renal clearance of fluoride in infants. The fluorosis-like effects on enamel of acidosis and hypobaric hypoxia are considered. The dynamic relationship between fluoride in blood and bone is reviewed and the minimal effect of caffeine on the pharmacokinetics of fluoride noted. The effects of fluoride on the gastric mucosa are commented on.

It is stated that the remarkable decline in dental caries that has occurred throughout much of the world can be largely attributed to the use of the ingested and topical forms of fluoride. Fluoride is seen as being widely regarded as the cornerstone of modern preventive dentistry. The early fluoridation studies are accepted quite uncritically and the works of authors like Sutton¹ and Diesendorf ² who critically re-examined those studies are ignored and omitted. Similarly, no mention is made of the recent comprehensive studies reporting little or no fluoride benefit in reducing dental caries.^3-12

In considering chronic fluoride toxicity, it is noted that, following the "equivocal evidence" for a link between high fluoride exposure and osteosarcoma in male rats, three recent reviews of the literature have been published.^13-15 A summary is given of the conclusions of the US Public Health Service report ¹⁴ and further discussion given of fluoride and bone fractures. It is concluded, in line with these reviews, that fluoride has little or no effect on bone strength, and that if there is an effect, either beneficial or detrimental, it is rather subtle. No reference is made to other reports and reviews which arrived at a quite different conclusion.^16,17 Nor is there any reference to the work of Alhava¹⁸ and Arnala¹⁹ on fluoride accumulation in bone. The question of fluoride leading to osteosarcoma is dealt with by the statement that there is no detectable risk of cancer in humans associated with the consumption of optimally fluoridated water. The report by Cohn ²⁰ is not referred to, nor are the critiques by Lee²¹ and Yiamouyiannis ²².

No discussion is given of the evidence for, or even the possibility of, central nervous system effects from fluoride. It is suggested that the unusually high brain concentrations reported by Phyllis Mullenix ²³ in weanling rats were likely to be the result of an analytical error.

Similarly, no reference is made to allergy or hypersensitivity, except to note that various "claims" were reviewed by Taves, 1979,²⁴ who concluded that "the data used to support the claims that fluoridation causes adverse effects in humans are not convincing".

Thus the book provides extensive information on the metabolism of fluoride and has gained a place in the training of dentists and public health specialists. However, because of the author’s uncritical acceptance of evidence for the efficacy of fluoride in reducing dental caries, and for its safety when consumed on a long-term basis, we are unable to assess this book as being truly scientific in its approach.

REFERENCES

1. Sutton PRN. Fluoridation: Errors and Omissions in Experimental Trials. Melbourne University Press, Melbourne 1960.
2. Diesendorf M. Have the benefits of water fluoridation been overestimated? International Clinical Nutrition Review 10 292-303 1990.
3. DiesendorfM.Themysteryofdecliningtoothdecay.Nature 322125-1291986.
4. Colquhoun J. Influence of social class and fluoridation on child dental health. Community Dentistry and Oral Epidemiology 13 37-41 1985.
5. Colquhoun J. Child dental health differences in New Zealand. Community Health Studies 11 85-90 1987.
6. Colquhoun J. Fluorides and the decline in tooth decay in New Zealand. Fluoride 26 125-134 1993.
7. Hildebolt CF, Elvin-Lewis M, Molnar S et al. Caries prevalences among geochemical regions of Missouri. American Journal of Physical Anthropology 78 79-92 1989.
8. Gray AS. Fluoridation: Time for a new base line? Journal of the Canadian Dental Association 53 763-765 1987.
9. Yiamouyiannis JA. Water fluoridation and tooth decay: Results from the 1986-1987 national survey of US schoolchildren. Fluoride 23 55-67 1990.
10. Jones T, Steelink C, Sierka J. An analysis of the causes of tooth decay in children in Tucson, Arizona. Paper presented to Annual Meeting of the American Association for the Advancement of Science, San Francisco, USA, February 22, 1994. Abstract in Fluoride 27 (4) 238 1994.
11. Teotia SPS, Teotia M. Dental caries: a disorder of high fluoride and low dietary calcium interactions (30 years of personal research) Fluoride 27 301-308 1994.
12. Ziegelbecker RC, Ziegelbecker R. WHO data on dental caries and natural water fluoride levels. Fluoride 26 263-266 1993.
13. Kaminsky LS, Mahoney MC, Leach J, Melius J, Miller MJ. Fluoride: benefits and risks of exposure. Critical Reviews in Oral Biology and Medicine 1 261-281 1990.
14. Review of Fluoride: Benefits and Risks. Ad Hoc Subcommittee on Fluoride. US Public Health Service, Department of Health and Human Services, Bethesda MD 1991.
15. Health Effects of Ingested Fluoride. National Research Council Subcommittee on Health Effects of Ingested Fluoride. US National Academy of Sciences, Washington DC, 1993.
16. Søgaard CH, Mosekilde L, Richards A, Mosekilde L. Marked decrease in trabecular bone quality after five years of sodium fluoride therapy - assessed by biomechanical testing of iliac crest bone biopsies in osteoporotic patients. Bone 15 (4) 393-399 1994.
17. Lee JR. Fluoridation and hip fracture: according to the National Research Council Report: "Health Effects of Ingested Fluoride". Fluoride 26 (4) 274-277 1993.
18. Alhava EM, Olkkomen H, Kauranen P, Kari T. The effect of drinking water fluoridation on the fluoride content, strength and mineral density of human bone. Acta Orthopædica Scandinavica 51 413-420 1980.
19. Arnala I, Alhava EM, Kauranen EM. Effects of fluoride on bone in Finland. histomorphometry of cadaver bone from low and high fluoride areas. Acta Orthopædica Scandinavica 56 161-166 1985.
20. Cohn PD. A brief report on the association of drinking water fluoridation and the incidence of osteosarcoma among young males. New Jersey Department of Health, Trenton, NJ, November 8, 1992.
21. Lee JR. Fluoridation and bone cancer. Fluoride 26 79-82 1993
22. Yiamouyiannis JA. Fluoridation and cancer: the biology and epidemiology of bone and oral cancer related to fluoridation. Fluoride 26 83-96 1993.
23. Mullenix PJ, Denbesten PK, Schunior A, Kernan WJ. Neurotoxicity of sodium fluoride in rats. Neurotoxicology and Teratology 17 (2) 169-177 1995 (Cf. Editorial: Neurotoxicity of Fluoride. Fluoride 29 (2) 57-58 1996).
24. Taves DR.Claimsofharmfromfluoridation.In:JohnsonT,TavesDR,OlsenTO (Eds). Continuing Evaluation of the Use of Fluorides. American Association for the Advancement of Science, Washington DC 1979 pp 295-321.

_______________________________

1. Dunedin School of Medicine, University of Otago Medical School, PO Box 913, Dunedin, New Zealand.
2. Education Department, University of Auckland, Auckland, New Zealand.

FLUORIDE 30 (2)  1997, p 110	International Society for Fluoride Research
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