Fluoride Concentrations in Human and Rat Bone

Authors


Send correspondence and reprint requests to Dr. Bawden. This project was supported in part by grant #RR-05333 from the National Institutes of Health.

Abstract

The most recent report on fluoride concentrations ([f]) in human bone was published over a decade ago. Such data are of interest in the context of changing patterns in systemic fluoride exposure. In the study reported here, bone samples were collected from 24 human subjects who underwent orthopedic surgery. Medical histories and the best possible life-time systemic fluoride exposure information were obtained from each subject. Bone samples were assayed for fluoride concentration using the acid diffusion, ion selective electrode method. For ash from whole bone, the lowest value was 378 ppm in a 16-year-old subject, and the highest value was 3,708 ppm in a 79-year-old person. Fluoride concentrations in bone were significantly correlated with age (r=.62). The regression line intercept at birth was 442 ppm, and the slope was 22 ppm per year. When measured separately, trabecular bone ash fluoride concentrations were significantly higher than the corresponding cortical bone values. Trabecular and cortical bone samples from rats' drinking water containing 75 ppm F were assayed for F. The mean trabecular bone fluoride concentration was significantly higher than the mean cortical bone concentration. There was close agreement between F assay results using a modification of the acid diffusion method and the method originally reported by Singer and Armstrong. The human bone ash [F] values reported in this study are similar to those reported from other North American subjects over the last three decades. These findings are of interest in the context of evidence indicating increased systemic fluoride exposure in the United States population. They may also be considered in efforts to evaluate the relevance of the National Institute of Environmental Health Sciences fluoride carcinogenesis study.

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