1) Following the publication of several clinical trials in the 1980s, where high doses of fluoride increased the rate of bone fracture among osteoporosis patients, a flurry of epidemiological investigations were published in the 1990s investigating the relationship between water fluoridation and bone fracture.

2) At least 9 studies, published since 1990, have detected an increased occurrence of hip fracture among people living in fluoridated (1 ppm), versus unfluoridated communities. 7 studies, however, have failed to detect this relationship.

3) The studies reporting a relationship between fluoridation and hip fracturehave generally been based on larger populations (a strength), but with less individual-specific data (a weakness), than studies reporting no association.

4) 3 the 7 studies which failed to find an increase in hip fracture in fluoridated areas, did find an increased rate of wrist fracture - a finding that may relate to fluoride's ability to reduce the density of cortical bone.

5) According to the National Research Council, the evidence is sufficient to conclude that 4 ppm fluoride in water increases the risk of bone fracture, while the evidence is "suggestive" that levels as low as 1.5 ppm can increase fracture rates.

6) A study investigating the relationship between bone fracture and dental fluorosis, found that the occurrence of bone fracture was higher among individuals - children and adults alike - who had with dental fluorosis, and that the risk of fracture increased with the increasing severity of the fluorosis.

Epidemiology - Relationship between Dental Fluorosis & Bone Fracture: (back to top)

Bone fractures vs Dean dental fluorosis index

SOURCE: Alarcon-Herrera MT, et al. (2001). Well Water Fluoride, Dental fluorosis, Bone Fractures in the Guadiana Valley of Mexico. Fluoride 34(2): 139-149. (See paper)

"A linear correlation between the Dean index of dental fluorosis and the frequency of bone fractures was observed among both children and adults."
SOURCE: Alarcon-Herrera MT, et al. (2001). Well Water Fluoride, Dental fluorosis, Bone Fractures in the Guadiana Valley of Mexico. Fluoride 34(2): 139-149.

Hip fractures vs Fluoride Level in Water (China)

SOURCE: SOURCE: Li Y, et al. (2001). Effect of long-term exposure to fluoride in drinking water on risks of bone fractures. Journal of Bone and Mineral Research 16:932-9.

"All members of the committee agreed that there is scientific evidence that under certain conditions fluoride can weaken bone and increase the risk of fractures. The majority of the committee concluded that lifetime exposure to fluoride at drinking water concentrations of 4 mg/L or higher is likely to increase fracture rates in the population, compared with exposure at 1 mg/L, particularly in some susceptible demographic groups that are more prone to accumulate fluoride in their bones."
SOURCE: National Research Council. (2006). Fluoride in Drinking Water: A Scientific Review of EPA's Standards. National Academies Press, Washington D.C. p. 146.

"In general, the hip fracture prevalence was stable up to 1.06 ppm of fluoride and then appeared to rise, although it did not attain statistical significance until the water fluoride concentration reached 4.32 - 7.97 ppm... The prevalence of hip fractures was highest in the group with the highest water fluoride."
SOURCE: Li Y, et al. (2001). Effect of long-term exposure to fluoride in drinking water on risks of bone fractures. Journal of Bone and Mineral Research 16:932-9.

"Residence in the higher-fluoride (4 ppm) community was associated with a significantly lower radial bone mass in premenopausal and postmenopausal women, an increased rate of radial bone mass loss in premenopausal women, and significantly more fractures among postmenopausal women."
SOURCE: Sowers M, et al. (1991). A prospective study of bone mineral content and fracture in communities with differential fluoride exposure. American Journal of Epidemiology 133: 649-660.

Hip fractures in Fluoridated vs Unfluoridated Areas (USA)

SOURCE: Danielson C, et al. (1992). Hip fractures and fluoridation in Utah's elderly population. Journal of the American Medical Association 268: 746-748.

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Hip fractures in Fluoridated vs Unfluoridated Areas (England)

SOURCE: Cooper C, et al. (1991). Water fluoridation and hip fracture. Journal of the American Medical Association 266: 513-514.

"This study examines the geographic distribution of hip fracture incidence in the United States at the county level. To this end, data are obtained from the Health Care Financing Administration (HCFA) and the Department of Veteran Affairs that identify all hospital discharges with a diagnosis of hip fracture for women aged 65 years and older for the period 1984 through 1987...After exclusions, 541,985 cases remained eligible for study... There is a weak positive association between the percent of county residents who receive fluoridated water and hip fracture incidence in the unadjusted analysis that is strengthened after adjustment."
SOURCE: Jacobsen SJ, et al. (1990). Regional variation in the incidence of hip fracture: US white women aged 65 years and olders. Journal of the American Medical Association 264(4): 500-2.

"We found a significant positive correlation between fluoride levels and discharge rates for hip fracture. This relationship persisted for both women and men... Using an appropriately weighted regression model, there appears to be a positive ecologic association between fluoride levels of county water supplies and fracture discharge rates. This ecologic association is consistent with a recently published study and others currently in progress."
SOURCE: Cooper C, et al. (1991). Water fluoridation and hip fracture. Journal of the American Medical Association 266: 513-514.

" An ecologic study compared fracture rates in 216 counties with natural fluoride levels greater than 0.7 ppm with rates in 95 counties with naturally low fluoride (less than 0.4 PPM) in the drinking water. In general, with increasing dose of fluoride in the drinking water the hip fracture ratio also increased."
SOURCE: Keller C. (1991) Fluorides in drinking water. Unpublished results. In: Gordon SL, Corbin SB. (1992) Summary of Workshop on Drinking Water Fluoride Influence on Hip Fracture on Bone Health.  Osteoporosis International 2: 109-117.

"We found a small but significant increase in the risk of hip fracture in both men and women exposed to artificial fluoridation at 1 ppm, suggesting that low levels of fluoride may increase the risk of hip fracture in the elderly."
SOURCE: Danielson C, et al. (1992). Hip fractures and fluoridation in Utah's elderly population. Journal of the American Medical Association 268: 746-748.

"In order to assess the association between water fluoridation and hip fracture, we identified 129 counties across the United States considered to be exposed to public water fluoridation and 194 counties without exposure...There was a small statistically significant positive association between fracture rates and fluoridation. The relative risk (95% confidence interval) of fracture in fluoridated counties compared to nonfluoridated counties was 1.08 (1.06 to 1.10) for women and 1.17 (1.13 to 1.22) for men."
SOURCE: Jacobsen SJ, et al. (1992). The association between water fluoridation and hip fracture among white women and men aged 65 years and older; a national ecologic study. Annals of Epidemiology 2: 617-626.

"The 1985 Fluoridation Census data were used for the 438 counties with populations over 100,000, which represents about 70% of the US population... The percentage of the population that received natural or adjusted fluoride (approximately 1 ppm) was estimated for each county. Medicare data for 1984-1987 were used to calculate the annual incidence of age adjusted hip fractures for white males and females age 65 and older. As the percentage of individuals exposed to fluoridated water increased within a county, the hip fracture rate generally rose for both sexes, but not in a smooth linear fashion... Adjustment for county latitude and longitude produced higher correlation values and significance for females and males."
SOURCE: May DS, Wilson MG. (1992). Hip fractures in relation to water fluoridation: an ecologic analysis. Unpublished Results: In Gordon SL, Corbin SB. (1992). Summary of Workshop on Drinking Water Fluoride Inflruence on Hip Fracture on Bone Health. Osteoporosis International 2:109-117.

The authors of this study conclude there is no association between fluoridation and hip fracture. However, their own data reveals a significant increase in hip fracture for men living in the fluoridated area. According to the study, "although a statistically significant increase in the risk of hip fracture was observed among Edmonton men, this increase was relatively small (RR=1.12)."
SOURCE: Suarez-Almazor M, et al. (1993). The fluoridation of drinking water and hip fracture hospitalization rates in two Canadian communities. American Journal of Public Health 83: 689-693.

"We found a higher risk of hip fractures for subjects exposed to fluorine concentrations over 0.11 mg per liter but without a dose-effect relation."
SOURCE: Jacqmin-Gadda H, et al. (1998). Risk factors for fractures in the elderly. Epidemiology 9: 417-423.

"[A]mong younger women, those aged 50-64 years, higher fluoride levels increased the risk of hip fractures."
SOURCE: Kurttio PN, et al. (1999). Exposure to natural fluoride in well water and hip fracture: A cohort analysis in Finland. American Journal of Epidemiology 150: 817-824.

This study found an age-specific, statistically-significant relationship between fluoridation and hip fracture in women 75-84 years old - RR = 1.43 (95% CI, 1.02-1.84). An increase in hip fractures was also found in women aged 85 and older, albeit not statistically significant - RR = 1.42 (CI, 0.98 - 1.87).
SOURCE: Hegmann KT, et al. (2000). The effects of fluoridation on degenerative joint disease (DJD) and hip fractures. American Journal of Epidemiology S18.

This study didn't find an association between fluoridation & hip fracture, but it did find an association between fluoridation and distal forearm fracture, as well as proximal humerus fracture. "Independent of geographic effects, men in fluoridated areas had modestly higher rates of fractures of the distal forearm and proximal humerus than did men in nonfluoridated areas."
SOURCE: Karagas MR, et al. (1996). Patterns of Fracture among the United States Elderly: Geographic and Fluoride Effects. Annals of Epidemiology 6: 209-216.

As with Karagas (1996), this study didn't find an association between fluoridation and hip fracture, but it did find an association -- albeit non-significant 1.6 (0.8-3.1) -- between fluoride exposure and elevated rates of forearm fracture.
SOURCE: Feskanich D, et al. (1998). Use of toenail fluoride levels as an indicator for the risk of hip and forearm fractures in women. Epidemiology 9: 412-6.

This study actually found a decrease in hip fractures among those exposed to fluoridation. The average exposure to fluoridation, however, was only 20 years, and thus the study may not be relevant to life-long exposure. Also, as with Feskanich (1998) and Karagas (1996), this study did find an association between fluoridation and another type of fracture - in this case, wrist fracture. "There was a non-significant trend toward an increased risk of wrist fracture."
SOURCE: Phipps KR, et al. (2000). Community water fluoridation, bone mineral density and fractures: prospective study of effects in older women. British Medical Journal 321: 860-4.