One of the numerous adverse manifestations following lead (Pb) exposure is production of free radicals and increased oxidative stress, which can lead to altered enyzme functioning and degradation of structural components in organism. The objective was to investigate the effects of Pb exposure on biomarkers of oxidative stress and antioxidant defence system in 15 adult male workers after occupational exposure to lead versus unexposed healthy controls. The impact of Pb on oxidative stress parameters was evaluated by measuring blood and urinary Pb concentrations, plasma levels of antioxidant enzymes catalase (CAT), superoxide dismutase (SOD), level of malondialdehyde (MDA) as the lipid peroxidation indicator, concentrations of carbonyl groups, plasma protein thiols and nitrites as biomarkers of protein oxidative modification. The results of MDA concentration revealed increased lipid peroxidation (P < 0.001), while the rise of protein carbonyl and nitrite levels (P < 0.001, P < 0.006, respectively) and decrease of plasma thiols (P < 0.001) indicated significant protein damage in Pb exposed workers, compared to unexposed controls. Increased activity of antioxidant enzymes SOD and CAT (P < 0.001) was also determined in exposed group. Elevated blood lead levels showed strong positive correlation (r=0.809, P < 0.001) with increased CAT concentration. Our findings indicate that Pb promotes oxidative damage in exposed subjects, and that increased lead content can affect the activity of antioxidant enzymes. Considering that oxidative stress has been recognized in etiology of many diseases, future explorations on impact of these changes in populations occupationally exposed to lead are suggested
