Respiratory Function and Oxidative Stress in Smoking Zinc Smelter Workers Exposed to Lead

Background/Objectives: Lead, a toxic heavy metal, is widely recognized as a hazardous environmental contaminant capable of disrupting physiological homeostasis by altering stress response mechanisms and impairing pulmonary function. A comparable detrimental factor is tobacco smoking, which represents one of the most prevalent addictions worldwide. The presented study aimed to evaluate the combined impact of cigarette smoking and occupational lead exposure on selected oxidative stress biomarkers and pulmonary function parameters. Methods: 453 male employees working in a zinc smelter were recruited for participation in the study. Participants were subsequently divided into two groups: current smokers (n = 209) and former smokers (n = 244). Each group was then further subdivided according to blood lead concentration into subgroups with high (>35 μg/dL) and low (<35 μg/dL) lead levels. Venous blood samples were collected for biochemical analysis of oxidative stress parameters, including total oxidant status (TOS), malondialdehyde (MDA), protein thiol content (PSH), total antioxidant capacity (TAC), and the oxidative stress index (OSI). In addition, spirometric evaluation was conducted. Results: Former smokers demonstrated significantly more favorable oxidative stress profiles and superior spirometric outcomes compared with current smokers. No statistically significant associations were observed between lead exposure levels and either biochemical or spirometric parameters. Conclusions: Cigarette smoking appears to exert a stronger adverse influence on oxidative balance and pulmonary function than occupational lead exposure.