I would very much like to see some explanation of the difference between natural calcium fluoride and the artificial fluorides used in water fluoridation.

Eileen Adelman

Managing Editor replies: There is a belief in some natural health circles that naturally occurring calcium fluoride is less harmful than other fluorides used for artificial water fluoridation. My understanding is that, in general, the fluoride ion is equally toxic, whatever its origin. In India and China naturally occurring fluorides cause much ill health, including crippling fluorosis. However, there are some differences:

1. The industrial waste products used for artificial water fluoridation are much more soluble than calcium fluoride, so are much more dangerous if there is an accidental overdosing of the water supply. Such accidents have occurred, causing sickness and sometimes deaths. However, at the relatively low concentrations occurring in artificially fluoridated water, calcium fluoride and the other fluorides are both soluble.
2. Sometimes naturally fluoridated water also contains minerals like calcium and magnesium, which are known to mitigate the toxic effects of the fluoride. Conversely, the industrial waste products used for water fluoridation almost always contain trace amounts of other toxins such as cadmium, lead and arsenic.
3. Recent research (see Editorial in this issue) indicates that silicofluorides, commonly used for fluoridation, are much more dangerous than previously realized, in that they increase the lead content of the water.

John Colquhoun

Neil not only reported anomalous results in his own research with fluoride but also referred to anomalous results which others got with fluoride. He called them "some unexplained anomalies."

Neil himself therefore conveniently disregarded his own data and erroneously concluded that "The solubility of enamel has been found to be related to its fluoride content."

I sent Neil a copy of everything I have ever published on fluoride and on paradoxical effects, including the 1964 article.

Albert Schatz PhD
6907 Sherman Street
Philadelphia, PA 19119, USA

1 Jenkins GN. Journal of Dental Research 42 (supplement to No. 1) 444 1963.
2 Schatz A. The importance of paradoxical effects of fluoride with respect to fluoridation and the toxicology of fluoride. Pakistan Dental Review 15 (4) October 1964.

The only results of Isaac et al that might be regarded as paradoxical refer to the four results comparing enamel from persons over 50 and under 20 years of age. The fluoride of the enamel is lower in the younger group (as expected) but in three out od the four comparisons the solubility is also lower. However, as Isaac et al point out, unknown changes may take place during aging which affect the solubility of enamel. Also, it is possible that dietary changes (for example, in trace elements) between the 1900s and the 1940s (when these teeth were forming) may influence the composition and solubility of enamel and over-ride the effect of fluoride.

I conclude that these results do not demonstrate a paradoxical effect of fluoride but show that many substances other than fluoride may affect enamel solubility. Provided that like is compared with like, the solubility of enamel has been found to be related to its fluoride concentration although this is only one means by which fluoride protects against caries.

Neil Jenkins
4 Jesmond Dene Terrace
Newcastle-upon-Tyne
NE2 2ET England

I refer to the letter of Gillian Durham,¹ New Zealand Director-General of Health, which criticized the article "New evidence on fluoridation" ². To justify her allegation that the article lacks "veracity" and is selective, Durham refers to the 1994 Public Health Commission report Water fluoridation in New Zealand ³. That report itself states that it "was essentially written by one person with experience in particular areas only" and "places some reliance on the quality of previous reviews that have been conducted. It is important to acknowledge that there are limitations with some of the reviews. Some may have tended to place unwarranted weight on the findings of previous expert reviews and lack wide representation of all the areas requiring expertise." This weakness is revealed by the report’s one-side reliance on small-scale pro-fluoridation studies to claim that fluoridation is cost-effective, rather than the various comprehensive studies which indicate little if any benefit. Yet Dr Durham implies that the PHC report is a watershed document and that only later papers have relevance.

However, the PHC report conceded that:
• "It is possible that there is a small increased risk of hip fracture associated with fluoridation"
• "a small increased risk of osteosarcoma in young men cannot be ruled out."
• "Fluoride intake from food is likely to be relevant to skeletal fluorosis in some areas (especially when vegetables are grown in fluorotic soil)"
• "individuals with longstanding and severe renal disease are theoretically at risk in temperate countries at usual water fluoridation levels"
• "Skeletal fluorosis might be occurring in individuals with either a long term intake or a metabolic susceptibility."

It was also admitted that skeletal fluorosis can occur at fluoride levels as low as 0.7-2.5 ppm, though it was qualified by the fact that the countries involved are nearly all tropical and therefore tend to have high water intakes. Many people in Australia and New Zealand also have high liquid intakes.

One has to question Durham’s judgement that the benefits of possibly preventing some dental caries outweigh the above admitted risks.

There has been recent publicity in New Zealand that dental caries is increasing with increasing poverty, in both fluoridated and nonfluoridated places. This fact disproves the assertion that fluoride is particularly advantageous to the lower socio-economic groups.

Bill Wilson
118 Forrest Hill Road
North Shore City
New Zealand

1. Durham G. Review of evidence on fluoridation (letter). Australian and New Zealand Journal of Public Health 21 548 1997. Reprinted in Fluoride 31 (3) 163-165 August 1998.
   
2. Diesendorf M, Colquhoun J, Spittle BJ, Everingham DN, Clutterbuck FW. New evidence on fluoridation. Australian and New Zealand Journal of Public Health 21 (2) 187-190 1997. Reprinted in Fluoride 30 (3) 179-183 August 1997.
   
3. Water Fluoridation in New Zealand. An Analysis and Monitoring Report. Public Health Commission, Wellington 1994.

FLUORIDE 31(4), 1998, pp 244-246	International Society for Fluoride Research
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