Plasma Heavy Metals and Coagulation Levels of Residents in E-waste Recycling Areas

Heavy metal exposure increased the risk of cardiovascular diseases (CVD). However, few studies investigated the effects of heavy metal exposure released by e-waste on coagulation, a risk factor for CVD. We conducted a cross-section study including residents living near and away from e-waste dismantling factories as exposed and reference groups for detecting plasma heavy metal concentrations, fibrinogen, activated coagulation factor X (FXa), and oxidative stress indicators of MDA and 8-isoprostane. We applied linear regression, ridge regression and Bayesian kernel machine regression (BKMR) models to estimate the associations between metal concentrations and coagulation. Furthermore, we explored the potential mediating role of oxidative stress. Our results showed that the concentrations of most heavy metals such as Cd, Co, Cr, Ni, Pb and fibrinogen in the exposed group were higher. Combined results of three statistical methods, we found Cd and Pb were associated with increased fibrinogen and FXa. In the linear regression, per one unit increase in log-transformed Cd and Pb was associated with 13.3% and 15.4% increase in fibrinogen, respectively. One unit increment in log-transformed Cd and Pb was associated with 14.2% and 15.6% higher FXa. The results of ridge regression were consistent with the basic linear regression. In the BKMR model, when all metals were at 60th or higher percentiles, the overall effect of the metal mixture was significantly associated with both fibrinogen and FXa compared to their 50th percentile. Increases in Cd and Pb were linked to higher oxidative stress, which potentially mediated the elevated coagulation levels. Our study suggests that exposure to heavy metals may increase coagulation levels and oxidative stress is a potential modulation pathway.