The Association between Fluoride and Bone Mineral Density in US Children and Adolescents: A Pilot Study

Abstract

The aim of this study was to examine the association between fluoride exposure and bone mineral density (BMD) in children and adolescents. We used data from the National Health and Nutrition Examination Survey (NHANES) 2015-2016. The fluoride concentrations in the water samples, plasma samples, and urine samples were measured electrometrically using an ion-specific electrode. Total body less head BMD (TBLH BMD) was measured using dual-energy X-ray absorptiometry (DXA). Weighted generalized linear regression models and restricted cubic splines (RCS) regression models were used to analyze the relationships between the three types of fluoride exposure and TBLH BMD. We performed subgroup analyses stratified by sex. A total of 1413 US children and adolescents were included in our study. In our linear regression models, we found inverse associations between fluoride concentrations in water and plasma and TBLH BMD. Additionally, we discovered a non-linear association between fluoride concentrations in water and plasma and TBLH BMD. No significant association or non-linear relationship was found between urine fluoride levels and TBLH BMD. This nationally representative sample study provides valuable insight into the intricate connection between fluoride exposure and skeletal health in children and adolescents.

Keywords: NHANES; adolescents; bone mineral density; children; fluoride.

Figure 1

Flow chart of the study participants from NHANES 2015–2016.

Figure 2

Dose–response relationships between concentrations of water fluoride and TBHL BMD. (a) Association between concentrations of water fluoride and TBHL BMD in the whole population; the model was adjusted for age, gender, race, Body Mass Index, poverty income ratio, physical activity, and milk product consumption. (b,c) Association between concentrations of water fluoride and TBHL BMD in males and females, respectively; the model was adjusted for age, race, Body Mass Index, poverty income ratio, physical activity, and milk product consumption. The red solid lines with their upper and lower ranges represent the estimated regression coefficient Beta and the 95% confidence interval. The red dotted lines correspond to the fluoride concentration at the curve’s inflection point.

Figure 3

Dose–response relationships between concentrations of plasma fluoride and TBHL BMD. (a) Association between concentrations of plasma fluoride and TBHL BMD in the whole population; the model was adjusted for age, gender, race, Body Mass Index, poverty income ratio, physical activity, and milk product consumption. (b,c) Association between concentrations of plasma fluoride and TBHL BMD in males and females, respectively; the model was adjusted for age, race, Body Mass Index, poverty income ratio, physical activity, and milk product consumption. The red solid lines with their upper and lower ranges represent the estimated regression coefficient Beta and the 95% confidence interval. The red dotted lines correspond to the fluoride concentration at the curve’s inflection point.

Figure 4

Dose–response relationships between concentrations of urine fluoride and TBHL BMD. (a) Association between concentrations of urine fluoride and TBHL BMD in the whole population; the model was adjusted for age, gender, race, Body Mass Index, poverty income ratio, physical activity, and milk product consumption. (b,c) Association between concentrations of urine fluoride and TBHL BMD in males and females, respectively; the model was adjusted for age, race, Body Mass Index, poverty income ratio, physical activity, and milk product consumption. The red solid lines with their upper and lower ranges represent the estimated regression coefficient Beta and the 95% confidence interval.

Figure 5

Correlation between concentrations of different fluoride. (a) Correlation between concentration of water fluoride and concentration of plasma fluoride. (b) Correlation between concentration of water fluoride and concentration of urine fluoride. (c) Correlation between concentration of plasma fluoride and concentration of urine fluoride. The red solid lines represent the fitted curve, while the blue shaded areas surrounding them denote the 95% confidence interval for the regression fit. Density plots along the periphery, either red or blue, represent the distribution of data points.