Hematological, cardiovascular and oxidative DNA damage markers associated with heavy metal exposure in electronic waste (e-waste) workers of Bangladesh
Sarker Masud Parvez, M. Mamun Huda, Mahbubur Rahman, Farjana Jahan, Masatake Fujimura, Shaikh Sharif Hasan, Nirupam Aich, Abul Hares, Zahir Islam, Rubhana Raqib, Luke D. Knibbs, Peter D. Sly
Abstract
Electronic waste (e-waste) contains hazardous elements such as lead (Pb), cadmium (Cd), mercury (Hg), and other toxic elements that pose significant health risks to the population directly exposed. We recruited 199 e-waste recycling workers and 104 non-exposed workers in Bangladesh and analyzed heavy metals in blood and hair, as well as hematological and cardiovascular parameters including, blood lipids and blood pressure. We fitted quantile regression models at 0.5 quantile to evaluate the impact of blood Pb, Cd, and total hair Hg (THg) on hematological and cardiovascular parameters and the role of oxidative DNA damage (8-OHdG as a biomarker) in mediatin the relationship between exposures and outcomes. Exposed workers had elevated median blood Pb (11.89 vs. 3.63 µg/dL), moderate blood Cd (1.04 vs. 0.99 µg/L), and lower level of THg (0.38 vs. 0.57 ppm) in hair than non-exposed workers. Adjusted estimates showed that Pb was positively associated with red blood cell (RBC), eosinophil count, eosinophil percentage; and negatively associated with mean platelet volume (MPV), platelet large cell ratio (P-LCR) and platelet volume distribution width (PDW) (all p≤0.05). Cd was only associated with 0.57 units increase in red blood cell distribution width (RDW) percentage (95 % CI: 0.18, 0.95). In cardiovascular outcomes, Pb was associated with 1.42 units decrease in triglyceride, 1.58 units increase in low-density lipoprotein (LDL), 0.07 units increase in LDL/HDL and 0.49 units increase in systolic blood pressure (all p≤0.05). No associations were observed between THg and hematological or cardiovascular parameters. Urinary 8-OHdG concentrations were lower, and it did not mediate exposure-outcome relationships (all p≥0.05). Our data imply that e-waste exposure impairs hematological parameters, blood lipids, and blood pressure secondary to elevated Pb levels and poses a threat to exposed individuals. As such, continuous monitoring in longitudinal studies is warranted to assess the dose-response relationship and identify effective control measures. • E-waste workers had elevated blood Pb, moderate blood Cd, and lower THg in hair. • E-waste exposure reflects the burden on eosinophils, MPV, P-LCR, total cholesterol, LDL and systolic BP. • Pb poses detrimental changes in RBC, MCHC, eosinophils, MPV, PDW, P-LCR, LDL, LDL/HDL and systolic BP. • No effect of Cd and THg on cardiovascular parameters were observed. • Lower concentrations of urinary 8-OHdG were observed, and it did not mediate the relationship between exposures and outcomes.