FLUORIDE 31 (3), 1998, pp 149-151	International Society for Fluoride Research	Table of Contents

R Lehmann, I M. Wapniarz, B Hofmann, B Pieper, I Haubitz, and E C Allolio
Warzburg, Germany

Abstract from Bone 22 (3) 273-278 1998

The role of drinking water fluoride content for prevention of osteoporosis remains controversial. Therefore, we analyzed the influence of drinking water fluoridation on the incidence of osteoporotic hip fractures and bone mineral density (BMD) in two different communities in eastern Germany: in Chemnitz, drinking water was fluoridated (1 mg/L) over a period of 30 years; In Halle, the water was not fluoridated. BMD was measured in healthy hospital employees aged 20-60 years (Halle: 214 women, 98 men; Chemnitz: 201 women, 43 men respectively) using dual-energy X-ray absorptiometry. Hip fractures in patients 35 years admitted to the local hospitals in the years 1987-1989 were collected from the clinic registers. There was no difference in age, anthropometric, hormonal, or lifestyle variables between the two groups. Mean fluoride exposure in Chemnitz was 25.2 ± 7.3 years. No correlation was found between fluoride exposure and age-adjusted BMD. We found no significant difference in spinal or femoral BMD between subjects living in Halle and Chemnitz (lumbar spine: 0.997 ± 0.129 (g/cm²) vs 1.045 ± 0.171 (g/cm²), p = 0.08, for men; 1.055 ± 0.112 (g/cm²) vs.1.046 ± 0.117 (g/cm2), p = 0.47, for women]. The fracture incidence showed an exponential increase with aging in men and women with an incidence about 3.5 times higher for women. In Chemnitz, we calculated an age-adjusted annual incidence of 142.2 per 100,000 for women; and 72.5 per 100,000 for men, respectively. In Halle the incidences were 178.5 per 100,000 for women and 89.2 per 100,000 for men. There was a lower hip fracture incidence after the age of 85 in women in Chemnitz (1391 per 100,000 in Chemnitz vs. 1957 per 100,000 in Halle, p = 0.006). Using the age-adjusted incidences, significantly fewer hip fractures occurred in Chemnitz in both men and women. In concIusion our study suggests that optimal drinking water fluoridation (1 mg/L), which is advocated for prevention of dental caries, does not influence peak bone density but may reduce the incidence of osteoporotic hip fractures in the very old.

Key Words: Bone mineral density; Drinking water fluoridation; Hip fracture incidence.

Reprints: Dr B Allolio, Medizinische Klinik der Universitat Wurzburg, Schwerpunkt Endokrinologie, Josef-Schneider- Str 2, 97080 Wurzburg, Germany.

The defects in the study are many and include the following.

Due to random variation, any two communities may have different fracture rates that have nothing to do with the factor being studied. This problem can be partially addressed by knowing the fracture rates at different ages in both communities prior to fluoridation of one of them. It may be, for instance, that the fracture incidence among elderly women in Halle has, for many years, been greater than that of the elderly women in Chemnitz. If so, one cannot argue that the difference observed here is due to fluoridation.

Total fluoride intake was not measured or even estimated. This could have been accomplished by urine fluoride tests. It is entirely possible that the total fluoride intake was essentially the same in the women with fractures in both communities.

Past or current estrogen therapy (ERT or HRT) was mentioned as part of the questionnaire obtained but not cited in its Table 2, showing characteristics of the study population. Estrogen is well known to be an anti- resorptive agent and thus a bone factor of some significance.

Water supply source was not identified. The difference between well water and river water used for drinking might be significant. Well water provides not only important minerals but these same minerals would bind to fluoride to reduce F-absorption. Also, if both of these industrial cities were on the same river and river water was their drinking water source, it would be important to know which city was down-stream of the other. Industrial pollutants in the river greatly affect general health and can react synergistically with fluoride.

Both communities are described as industrial cities. If the industrial activity involved coal burning, atmospheric fluoride would significantly nullify any difference in water fluoride intake in these communities.

Bone health involves many other variables, so few of which are considered in this study that no meaningful conclusion can be drawn. This absence of considering other variables is common in the pro-fluoride dental literature.

As the authors admit, fracture incidence in both of these communities is lower than that found in former West Germany. They assert this is due to "unexplained regional differences" which is no explanation at all but allows the inference that communities only 100 Km apart can also have "unexplained regional differences." It is likely, therefore, that other factors, such as diet, specific nutrients, environmental toxins, deaths from other causes, and other factors rather than water fluoridation affected the fracture incidence.

There is another curious thing about this study. Since the study was published in 1998 and the data were collected in 1989, one wonders why it took 9 years to write it? On the other hand, if the study was written in 1998, why choose only the 2-year time span of 1987-1989 instead of, say, a 5-year or 10-year time span for which data clearly were available. Given the known variability of fracture incidence, any given 2-year incidence can not be expected to be as representative as a 10-year mean incidence. Was there something the authors liked about this particular 2-year time span?

Finally, one must look at the one age period in which a statistically significant fracture incidence difference exists between the two communities. Why would women over age 85 experience a higher fracture incidence in Halle than in fluoridated Chemnitz? When fluoridation was started in Chemnitz, in 1959, the 85-year old women (in 1957-1989) were postmenopausal, i.e., when bone remodelling is much less active, weaker bones at age 85 suggest weaker bones prior to menopause. These women were in their late 30's during the war. Was there something about the war experience or the post-war recovery period that adversely affected Halle women more than Chemnitz women? Is this the cause of their increased hip fracture incidence fifty years later? This study provides no information to answer this question. There exists no known mechanism by which fluoridated water could reduce fracture incidence in the very elderly without some sign of the same benefit in earlier age groups. Therefore, it is likely that this isolated divergence of fracture incidence has no relation to water fluoridation. The only finding of this study that seems sturdy is the fact that fluoridation produced no apparent gain in bone mineral density at any age, contrary to the claims of many fluoridation proponents.

The evidence of this study strongly supports the null hypothesis, namely, that water fluoridation had no effect on bone mineral density or fracture incidence.

John R. Lee, MD
9620 Bodega Hwy
Sebastopol, CA 96472, USA

FLUORIDE 31 (3), 1998, pp 149-151	International Society for Fluoride Research
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