Association between multiple metal exposure and bone mineral density among Chinese adults

Previous studies about metal exposures and bone mineral density (BMD) have mainly focused on individual metals. The objective of this study was to explore the association of single and multiple metal exposures with BMD among Chinese adults. We recruited 2922 participants from Tongji Hospital in Wuhan, China. The urinary concentrations of 21 metals were measured by the inductively coupled plasma mass spectrometer. BMD was measured using dual-energy X-ray absorptiometry. We applied linear regression and Bayesian kernel machine regression (BKMR) to examine the association of single and multiple metal exposure with BMD, respectively. The linear regression model showed that cadmium (Cd) and strontium (Sr) were associated with lower BMD (all P-trend < 0.05). Compared with the lowest quantiles, the β (95% CI) of BMD in the highest quartile of Cd and Sr was - 0.032 (- 0.049, - 0.016) and - 0.033 (- 0.049, - 0.018), respectively. The BKMR results showed that co-exposure to 21 metals was negatively associated with BMD among the total participants and males. Our study suggested that exposure to multiple metals was negatively associated with BMD, particularly among males. More prospective studies are needed to identify these associations and reveal the underlying mechanisms.