Electricity substations take electricity from power lines and transformer lines to transform it from high to low voltage and distribute to the consumers. These substations generate low frequency electromagnetic fields similar to those emitted from over head power lines and electrical appliances at home. The present study is focused on assessing the potential bioeffects of Extremely Low Frequency Electromagnetic Fields (ELF-EMFs) on melatonin level and oxidative stress biomarkers, in subjects occupationally exposed to 132 kV high voltage substation in Hyderabad, India. These subjects are involved in maintenance and installation of power line distribution at electricity transmission network. The ELFEMFs exposed subjects (n = 142) included the electric utility workers, who were compared with age, and socioeconomic status matched controls (n = 151). The subjects were professionally categorized based on their job titles, with different exposure levels, as administrative workers (low exposure), maintenance workers (medium exposure) and liveline workers (high exposure). The plasma melatonin levels were significantly suppressed in the high exposed subjects i.e., hotline workers (p < 0.05). The oxidant status levels of plasma Malondialdehyde (MDA) and Nitric Oxide (NO) showed significantly increased levels in all the exposed subjects (p < 0.05). The activity levels of erythrocyte antioxidative enzyme when compared to control subjects were significantly reduced in the exposed subjects of all the categories (p < 0.05).
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