Study of synergistic DNA-damaging effects of low-intensity 2450 MHz microwave and 4-nitroquinoline on human lymphocytes in vitro

Objective: To study the synergistic DNA-damaging effects of low-intensity 2450 MHz micro-wave (MW, 5.0 mW/cm2) and 4-nitroquinoline (4-NQO) on human lymphocytes. Methods: The DNA damages of human lymphocytes treated with microwave and 4-NQO were detected using the comet assay. Three combination-exposure ways of MW and 4-NQO were used: MW irradiation before 4-NQO exposure (MW+4-NQO), simultaneous exposure to MW and 4-NQO(MW-4-NQO), and MW irradiation after 4-NQO exposure (4-NQO+MW). Results: The differences of DNA-damage indexes (comet tail length, comet shape and total comet length) between MW group and control group were not significant (P>0.05).When the dose of 4-NQO was 50 μmol/L or 25 μmol/L, the differences of DNA-damage indexes between MW+4-NQO group and corresponding 4-NQO group were significant (P<0.05 or P<0.01). The differences of DNA-damage indexes between MW-4-NQO group or 4-NQO+MW group and corresponding 4-NQO group were not significant (P>0.05). Conclusion: Low-intensity 2450 MHz microwave does not induce DNA-damage directly, but could enhance the DNA-damaging effects induced by 4-NQO when human lymphocytes have been treated with MW irradiation before 4-NQO exposure