CATALASE AND SUPEROXIDE-DISMUTASE ACTIVITIES AS BIOMARKERS OF OXIDATIVE STRESS IN WORKERS EXPOSED TO MERCURY VAPORS

For this article we investigated the role of three blood antioxidant e nzyme activities and total antioxidant status (TAS) as biological mark ers of oxidative stress in workers exposed to mercury (Hg-o) vapors. T wenty-two female workers took part in the study. The examination inclu ded a questionnaire on age, educational level, occupational history, a ctual health status, previous accidents and diseases, smoking and diet ary habits, and alcohol consumption. Blood and urine sampling for biol ogical analyses completed this examination. The workers were classifie d into three subgroups according to their creatinine-corrected Hg conc entration in urine. Blood antioxidant enzyme activities and TAS were c ompared between groups with nonparametric distribution-free methods. A significant difference existed in catalase activity and a slight, but not significant, difference existed in Cu2+/Zn2+ superoxide dismutase (Cu2+/Zn2+ SOD) activity between tile three groups. No differences we re observed in either tile glutathione peroxidase activity or the TAS between these groups. Catalase and Cu2+/Zn2+ SOD activities were incre ased in the groups of workers with higher creatinine-corrected urinary Hg concentrations when compared with the group of lower creatinine-co rrected urinary Hg concentrations. Catalase activity was positively co rrelated with the creatinine-corrected concentration of Hg in urine, a nd Cu2+/Zn2+ SOD activity was slightly correlated with the creatinine- corrected concentration of Hg in urine. The role of erythrocyte catala se and Cu2+/Zn2+ SOD activities we have measured is in agreement with the hypothesis of the involvement of reactive oxygen species productio n as an important event in chronic exposure to Hg-o vapors in humans. In spite of the small size of the sample, these results indicate that erythrocyte catalase and Cu2+/Zn2+ SOD activities could be considered as markers of biological effect in workers exposed to Hg-o vapors.