Fluoride in Drinking Water, Diet, and Urine in Relation to Bone Mineral Density and Fracture Incidence in Postmenopausal Women

Introduction

Exposure to fluoride occurs mainly through drinking water, which may include fluoride from natural sources and fluoride added to prevent tooth decay. Naturally occurring fluoride concentrations can vary substantially, from insignificant to well above the World Health Organization (WHO)-recommended limit of 1.5mg/L$1.5\mathrm{mg}/\mathrm{L}$ (WHO 2006), whereas the concentration in artificially fluoridated water is typically around 0.7mg/L

$0.7\mathrm{mg}/\mathrm{L}$ (U.S. Department of Health and Human Services Federal Panel on Community Water Fluoridation 2015). Although low levels of fluoride are beneficial for oral health, the therapeutic range is narrow, and it is well established that individuals living in areas with high naturally occurring fluoride have an increased risk of dental and skeletal fluorosis (the former a result of early life exposure) (NRC 2006). Because of its ability to induce bone formation (Farley et al. 1983), the antifracture effect of fluoride was extensively studied in randomized controlled trials (RCTs) in the early 1990s. However, although high-dose fluoride therapy increased bone mineral density (BMD), it had no effect on the overall vertebral fracture rate, and it increased the risk of nonvertebral fractures (Haguenauer et al. 2000; Riggs et al. 1990)............ 

Conclusion

The risk of hip fractures was increased among Swedish women who had the highest levels of urine fluoride excretion and the highest estimated fluoride intake from beverages and food relative to women with the lowest levels of each exposure. Our findings, which are consistent with the effects of high fluoride exposures observed in RCTs (resulting in a denser but more fragile skeleton), suggest that long-term consumption of tap water with a fluoride concentration of 1mg/L$1\mathrm{mg}/\mathrm{L}$, which is below the 1.5mg/L$1.5\mathrm{mg}/\mathrm{L}$ maximum concentration recommended by the WHO, may adversely affect bone health in postmenopausal women.