Increased Oxidative Stress Markers in Subjects Occupationally Exposed to Heavy Metals May Be Due to Poor Antioxidant Responses to Stressors

Artisanal miners (AM) and farmers who use water from abandoned mines for irrigation (FA) are occupationally exposed to heavy metals. Understanding their antioxidant-responses to such stressors warrants investigation. The oxidative stress levels and antioxidant-responses in 45 test subjects (AM, 30; FA, 15) and 15 control subjects who live far away from any mine (CS) were investigated. Blood concentrations of malondialdehyde (MDA) and reduced glutathione (GSH) and the activities of glutathione peroxidase (GPx), glutathione s-transferase (GST) and catalase (CAT) of the 60 subjects were determined/assayed using standard methods. Appropriate statistical tests were used to analyze the data. MDA concentrations were significantly higher (P 0.05) in all groups. However, GST activity (µmol/min/ml) was significantly reduced in the AM (8.8 ± 1.0) and FA (8.7 ± 0.5) groups compared to the CS group (10.4 ± 2.3). The inability of subjects occupationally exposed to heavy metals to increase the activity of their antioxidant enzymes and the concentration of GSH may be responsible for the heightened lipid peroxidation found in them.