BACKGROUND: It has been found that the concentrations of fluoride in drinking water and brick-tea are high in the grassland area of Inner Mongolia, China. We undertook a cross-sectional study to evaluate the influence of drinking water and brick-tea water fluoride levels on bone status.
SUBJECTS AND METHODS: We -studied 38 and 46 healthy Mongolian women with brick-tea drinking habit in a grassland area and without in an urban area respectively, aged 20 to 34. Speed of sound (SOS), broadband ultrasound attenuation (BUA) and stiffness index (SI) were measured at the calcaneus using quantitative ultrasound (QUS) analysis, while the second metacarpal bone mineral density (BMD) and metacarpal cortical index (MCI) of dominate and non-dominate hands were measured using computed X-ray densitometry (CXD). We analyzed fluoride contents in well water and brick-tea water from the household of each subject in the grassland area and in city water from one source in the urban area.
RESULTS AND DISCUSSIONS: Fluoride concentrations in drinking water were remarkably higher in the grassland area (1.14-5.39 ppm,. mean= 2.69 ppm, well water) than that in the urban area (0.31 ppm, city water). Fluoride concentrations in brick-tea water were 2.61-10:87 ppm (mean= 5.14 ppm). Compared with women in the urban area, those in the grassland area were found to have significantly lower bone mass in SOS (p<0.01), non-dominate-hand MCI (p<0.05)and dominant-hand MCI (p<0.05), after adjusted by age and body mass index. Brick-tea water fluoride concentration indicated significant correlations with dominate-hand MCI (r=-0.49, p<0.01) and non-dominate-hand MCI (r=-0.49, p<0.01) in the grassland area; but· not with-SOS. No correlations between-drinking water-fluoride and bone-mass indexes were found in the grassland area. These results suggest that excessive intake of fluoride may decrease bone mass, and that intake of fluoride from brick-tea may play an important role in this grassland area’s low bone mass. To further clarify the influence of fluoride exposure on bone, correlations of fluoride exposure and bone metabolism are under investigation.
CONCLUSION: This study shows that low bone mass in the grassland young women is related with high fluoride concentration in brick-tea water.