A collaborative study by US and Chinese researchers, who compared the bone fracture prevalence of Chinese communities with naturally occurring fluoride concentrations in water ranging from 0.25 ppm to 7.97 ppm, found the lowest rates in those where the concentration was 1 ppm. (1)

In total, the researchers recruited just over 8,200 randomly selected Chinese males and females aged 50 and over.  Each person needed to have lived continuously in their existing community for at least 25 years and to have had lifelong exposure to the same level of naturally occurring fluoride in their water.

Data collected about the participants for the study included medical history, alcohol and tea consumption, levels of physical activity and whether or not they were or had been smokers.  In cases where individuals reported having had bone fractures, the researchers sought where possible to retrieve medical records and original x-rays.

Water samples taken from the different communities were also analysed to check concentrations of aluminium, calcium, selenium, lead, cadmium, iron, zinc and arsenic.  Surveys were also conducted to ensure that there were no other potential sources of fluoride, including pollution.

Higher bone fracture rates in areas with relatively low or relatively high fluoride levels in water

Both the populations with the lowest (0.25- 0.34 ppm) and the highest (4.32-7.97 ppm) fluoride levels in drinking water showed a significantly higher prevalence of overall fractures than those residing in areas where the fluoride in water was 1.00 -1.06 ppm.

Communities with 1.00 -1.06 ppm of fluoride in their water had a hip fracture prevalence similar to those with lower concentrations.  A statistically significant higher prevalence was where the fluoride concentration reached 4.32 – 7.97 ppm.

Possibility of a ‘beneficial window’ of fluoride intake for bone health but need for more studies to confirm findings

The authors of the study concluded: “The data appear to suggest that there may be a ‘beneficial window’ of fluoride intake for bone health, because an increased risk of overall bone fractures was detected in both the populations with deficient and excessive fluoride in drinking water.”  However, they pointed to the limitations of ecological studies and called for further investigations to confirm their findings.

1. Li Y, Liang C, Slemenda CW, Ji R, Sun S, Cao J, Emsley CL, Wu Y, Ying P, Zhang Y, Gao S, Zhang W, Katz BP, Niu S, Johnston CC Jr (2001): Effect of long-term exposure to fluoride in drinking water on risks of bone fractures.  Journal of Bone and Mineral Research, 16: 932-939.