Lead Exposure Is Associated With Protein Carbonylation Content and DNA Methylation in Pb-Battery Recycling Workers

Previous studies on lead (Pb)-mediated oxidative stress and DNA methylation have been evaluated independently. The present study integrates Pb exposure assessment with oxidative protein damage, total antioxidant capacity (TAOC), and global DNA methylation in occupationally exposed Pb-battery recycling workers and evaluates whether BPbLs independently predicts these biomarkers after adjustment to potential confounding variables. We also examined the relationship between oxidative stress markers and epigenetic alterations We compared 78 Pb-battery recycling male workers with 65 unexposed male controls. Demographic data were obtained using a questionnaire. Serum TAOC and protein carbonyl content were quantified using commercially standardized assays. 5-mC DNA methylation and blood Pb levels (BPbLs) were measured from whole blood using commercially standardized kit and inductively coupled plasma optical emission spectroscopy, respectively. The exposed group showed significantly higher BPbLs (p < 0.0001) and protein carbonyl content (p < 0.0001), and lower TAOC (p < 0.0001) and 5-mC DNA methylation (p < 0.0001) than controls. 5-mC DNA methylation was negatively correlated with protein carbonyl content (p = 0.0001), indicating an association between protein oxidants and epigenetic alterations. Multiple linear regression models accounted for 25.3%, 24.4%, and 36.9% of the variance in protein carbonyl content, TAOC, and 5-mC DNA methylation, respectively. BPbLs emerged as an independent predictor across all three outcomes, while smoking and tobacco chewing provided additional contributions to TAOC and 5-mC DNA methylation, respectively. This study observed that the occupational Pb exposure assessment is associated with oxidative stress and epigenetic alterations among Pb-recycling workers and further confirms the true cause-and-effect relationship suggested by prospective longitudinal design studies.