Associations between exposure to metal mixtures and insufficient bone strength: a cross-sectional study among children aged 2-6 years

Abstract

Abstract Heavy metal exposure has been widely recognized as a risk factor for human health. However, epidemiological studies of associations between exposure to metal mixtures with bone strength among preschoolers are limited. We estimated the associations of 23 urinary metals with the risk of insufficient bone strength (IBS) among 1399 children aged 2–6 years in China. Urine concentrations of 23 metals were measured using inductively coupled plasma mass spectrometer and bone strength was measured using the quantitative ultrasound instrument. The weighted quantile sum (WQS) and bayesian kernel machine regression (BKMR) models were conducted to investigate the associations between exposure to metal mixtures and IBS. In the single metal exposure model, urine cobalt and zinc were identified to be negatively associated with IBS, whereas urine lead was positively associated with IBS. Furthermore, WQS regression and BKMR analyses consistently showed that exposure to metal mixtures was inversely related to IBS, and cobalt was the main contributor to the combined effects. Such associations were more evident in children aged 2–4 years. These findings indicated that exposure to metal mixtures was associated with bone strength among children. These findings need further validation in prospective studies.