Fluorine Concentration in Drinking Water and Fractures in the Elderly

Journal of the American Medical Association

1995; Volume 273; Page 775-776.

Fluorine Concentration in Drinking Water and Fractures in the Elderly

To the Editor. - Although it was initially hypothesized that fluorine could protect against hip fractures, three recent studies have reported an increase in the risk of hip fractures in communities exposed to fluoridated water, (1-3) and a fourth suggested no association between water fluoridation and hip fracture. (4) Among these studies, three were ecological and did not take into account major individual risk factors. (2-4) In the only study using individual data, (3) the fluorine concentrations were high ( mg/L in the control communities and 4 mg/L in the higher-fluorine community).

We report results of a population-based study of the relationship between concentrations of fluorine and calcium in drinking water and risk of hip fractures or fractures at any site. Results reported herein are based on the sample of the Paquid study (5) of normal and pathological aging, which comprised 3777 subjects aged 65 years or older living at home in 75 civil parishes of southwestern France. The mean time that individuals in the sample had remained in the same parishes was 41 years. Data about fractures were available for 3578 subjects; 503 (14.1%) indicated they had at least one fracture at any site during the previous 10 years and 70 (1.95%) had at least one hip fracture. Calcium and fluorine concentrations were measured in water from each parish; data from two measurements surveys performed in 1991 (6) and data collected routinely since 1991 were used.

Odds Ratio (OR) and 95% Confidence Interval (CI) for the Effect of Fluorine and Calcium Concentrations in Drinking Water on Risk of Hip Fractures Adjusted for Age, Sex, and Quetelet Index, and on Risk of Any Fractures Adjusted for Age and Sex.
	Hip Fractures		Any Fractures
Concentration, mg/L	OR	95% CI	OR	95% CI
Fluorine
0.05-0.11	1		1
0.11-1.83	1.86	1.02-3.26	0.98	0.80-1.21
Calcium
8.90-75	1		1
75-146	1.32	0.78-2.22	1.07	0.88-1.30

All analyses were performed using a multiple logistic regression. Five personal characteristics were studied: age, sex, Quetelet index (weight in kilograms divided by the square of height in meters), smoking status, and sport activity. Only age (odds ratio [OR], 2.5 for 10 years; 95% confidence interval [CI], 1.7 to 3.6), sex (OR, 2.3 for women vs men; 95% CI, 1.2 to 4.3), and Quetelet index (OR, 0.90; 95% CI, 0.84 to 0.97) were significantly associated with the risk of hip fractures, and only age (OR, 1.2; 95% CI, 1.1 to 1.4) and sex (OR, 2.0; 95% Cl, 1.6 to 2.4) were significantly associated with the risk of any fractures. These variables were used as adjustment variables in the subsequent analyses.

Two classes of fluorine and calcium concentration were defined, using the median of the distribution among parishes as the cutoff point. The main results are shown in the Table. The risk of hip fractures was significantly higher when water fluorine concentration was higher than 0.11 mg/L (P=.04), and this result persisted when using a mixed-effect logistic regression for taking into account the grouping of the subjects in parishes. No association was found between hip fractures and water calcium (P=.30) and between fractures at any site and water fluorine (P=.88) or water calcium (P=.50). Thus, adjusting for major individual risk factors, this study suggests a deleterious effect of fluorine in drinking water on the risk of hip fractures, even for moderate concentrations of fluorine, and no effect on other kinds of fractures.

Helene Jacqmin-Gadda, PhD
Daniel Commenges, PhD
Jean-Francois Dartigues, MD, PhD
Universite de Bordeaux
Bordeaux, France

1. Sowers MR, Clark MK, Jannausch ML, Wallace RB. A prospective study of bone mineral content and fracture in communities with differential fluoride exposure. Am J Epidemiol. 1991;133:649-660.

2. Danielson C, Lyon JL, Egger M, Goodenough GK. Hip fractures and fluoridation in Utah's elderly population. JAMA 1992;268:746-748.

3. Jacobsen SJ, Goldberg J, Cooper C, Lockwood SA. The association between water fluoridation and hip fracture among white women and men aged 65 years and older: a national ecologic study. Ann Epidemiol. 1992;2:617-626.

4. Suarez-Almazor ME, Flowerdew G, Saunders D, Soskolne CL, Russel AS. The fluoridation of drinking water and hip fracture hospitalization rates in two Canadian communities. Am J Public Health. 1993;83.689-693.

5. Dartiques JF, Gagnon M, Barberger-Gateau P, et al. The Paquid epidemiological program on brain aging. Neuroepidemiology. 1992;11:14-18.

6. Jacqmin H, Commenges D, Letenneur L, Barberger-Gateau P, Dartigues J-F. Components of drinking water and risk of cognitive impairment in the elderly. Am J Epidemiol. 1994;139:48-57.

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