Auteurs

Kumar S, Kumar Kesari K, Behari J. 2010. Evaluation of genotoxic effects in male Wistar rats following microwave exposure. Ind J Exp Bio 48: 586-592.

Background
Biological effects related to electromagnetic field (EMF) exposure depend on dose and long-term cumulative effects. Most studies have indicated disruption of carbohydrate, lipid, and protein metabolism which may induce changes in enzyme activity and gene expression thereby causing DNA damage.

Objective
The objective of this study was to investigate the genotoxicity of EMF exposure by examining its effects on micronuclei formation, the antioxidant enzymatic system, and reactive oxygen species formation in adult male rats.

Methods
Male Wistar rats 70-day old were separated into exposure groups and sham groups, each group containing 6 rats. Animals were continuously exposed for 2 hours per day for 45 days to either 10 GHz EMF radiation with a power density of 0.241 mW/cm2 and a specific absorption rate (SAR) of 0.014 W/kg, or 50 GHz EMF radiation with a power density of 0.86 mW/cm2 and a SAR of 0.008W/kg. Rats were sacrificed, blood samples were collected by cardiac puncture, and micronuclei, reactive oxygen species, and antioxidant enzyme activity were measured in blood cells and serum.

Results
Reactive oxygen species levels in the 10 GHz and 50 GHz exposed groups were significantly higher (P<0.03 and P<0.04, respectively) than in the sham-exposed groups. Micronuclei measurement by flow cytometry indicated that the ratios of polychromatic erythrocyte to normochromatic erythrocyte populations were significantly lower in both the 10 GHz and 50 GHz exposed groups (P<0.05 for each) when compared to sham exposed groups. Antioxidant activity was lower in the 10 GHz and 50 GHz exposed groups for both glutathione peroxidase and superoxide dismutase when compared to the activity in the sham exposed groups but catalase activity was higher in treatment groups than in the sham-exposed group.

Interpretation and Limitations
EMF radiation affected micronuclei formation, decreased activity of cell defence mechanisms, and caused an overproduction of reactive oxygen species. The effect of EMF on reactive oxygen species production was greater at 50 GHz than at 10 GHz which suggests a greater macromolecular response to a higher resonance. Micronuclei were induced in erythropoetic cells due to the interaction of DNA with reactive oxygen species and the overproduction of reactive oxygen species decreased glutathione peroxidase and superoxide dismutase activity but increased catalase activity. These results indicate that radiation at 50 GHz has greater effects than radiation at 10 GHz.  The main limitation of this study is the small sample size. Only 6 rats were used in each group.

Conclusion
This study suggests that exposure to EMF radiation has negative effects on micronuclei formation and reduces the activity of cell defence mechanisms by overproducing reactive oxygen species.

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