Background: Chronic occupational exposure to heavy metals — particularly lead and cadmium — is a recognised public health hazard in industrialising countries such as India. These metals generate reactive oxygen species (ROS) by Fenton-type catalysis, displacement of essential metal cofactors, and depletion of thiol-based antioxidants, thereby producing systemic oxidative stress and progressive depletion of the endogenous antioxidant defence network. Aim: The present case-control study aimed to evaluate the activity of erythrocyte antioxidant enzymes and the levels of selected oxidative damage markers in workers chronically exposed to lead and cadmium in a battery and lead-acid recycling industry, and to compare these with non-exposed controls drawn from the same socio-demographic milieu. Materials and Methods: A hospital-based case-control study was conducted in the Department of Biochemistry, South India, between July 2016 and March 2017. Seventy (n=70) male battery industry workers chronically exposed to lead and cadmium and 70 age-matched non-exposed male office workers were recruited. Blood lead, blood cadmium, urinary delta-aminolevulinic acid (δ-ALA), erythrocyte SOD, catalase, glutathione peroxidase (GPx), glutathione reductase (GR), reduced glutathione (GSH), total antioxidant capacity (TAC), serum MDA, protein carbonyls, and 8-OHdG were measured using validated atomic absorption spectrophotometric, kinetic spectrophotometric, and ELISA methods. Independent samples t-test, Pearson correlation, and multivariate regression were used. Results: Exposed workers showed significantly elevated blood lead (28.4 vs 4.6 µg/dL), cadmium (3.84 vs 0.84 µg/L), and oxidative damage markers (all p<0.001), accompanied by significantly reduced antioxidant enzyme activities and TAC (all p<0.001). Blood lead correlated negatively with SOD (r=-0.612, p<0.001) and positively with MDA (r=0.586, p<0.001). Conclusion: Chronic occupational lead and cadmium exposure produces a profound depletion of erythrocyte antioxidant enzymes coupled with extensive lipid, protein, and DNA oxidative damage. Routine biological monitoring of redox indices is recommended for early detection and risk mitigation in exposed Indian workers.

Environmental toxin; Lead exposure; Cadmium; Antioxidant enzymes; Oxidative stress; Occupational health; Glutathione.