Low-dose fluoride and lead co-exposure alters bone mineral density in youth: A nationally representative cross-sectional study.

PURPOSE: Both lead and fluoride can accumulate in the skeleton and cause skeletal damage; however, it remains unclear whether their co-exposure exacerbates the impacts on bone tissue. This study aims to investigate the relationship between co-exposure to fluoride and lead and changes in bone mineral density (BMD) among children and adolescents.

METHODS

Data were derived from 2378 participants in the National Health and Nutrition Examination Survey (2013-2016). Laboratory professionals measured the concentrations of plasma and water fluoride, whole blood and urine lead, BMD of the lumbar spine, pelvic, left and right legs. Linear regression, interaction and restricted cubic spline models were used to analyze the relationship between fluoride and lead exposure and BMD.

RESULTS

Plasma and water fluoride showed U-shaped associations with BMD, while blood and urinary lead demonstrated inverse nonlinear relationships with lumbar spine BMD-initially steep decline followed by an attenuated decrease (P-overall < 0.05, P-nonlinear < 0.05). Furthermore, the BMD of the pelvis and legs decreased as lead levels increased (P < 0.05). The interaction model of plasma fluoride and blood lead showed that, for every 1-unit increase in the interaction term, the BMD of the lumbar spine, left and right legs decreased by 1.679, 3.104, and 3.068 (P < 0.05), respectively.

CONCLUSIONS

This study demonstrates that exposure to fluoride and lead is associated with changes in BMD among youth. Co-exposure to fluoride and lead exacerbates changes in BMD more than single exposure, suggesting synergistic effects on bone impairment.