Radiofrequency (microwave) radiation exposure of mammalian cells during UV-induced DNA repair synthesis

The effect of continuous-wave (CW) and pulsed-wave (PW) radiofrequency radiation (RFR) in the microwave range on UV-induced DNA repair has been investigated in MRC-5 normal human diploid fibroblasts. RFR exposure at power densities of 1 (or 5) and 10 mW/cm² gave a maximum specific absorption rate (SAR) (at 10 mW/cm²) of 0.39 ± 0.15 W/kg for 350 MHz RFR, 4.5 ± 3.0 W/kg for 850 MHz RFR, and 2.7 ± 1.6 W/kg for 1.2 GHz RFR. RFR exposures for 1 to 3 h at 37°C, in either continuous-wave or pulsed-wave modes, had no effect on the rate of repair replication label incorporated into preexisting UV-damaged DNA. RFR exposures (PW), with a constant medium temperature of 39°C at 350 and 850 MHz during the repair period after UV damage, also had no effect. Assay for induction of repair synthesis by RFR exposure alone in non-UV irradiated cells was negative for the 350-, 850-, and 1200-MHz CW and PW RFR at 37°C and the 350- and 850-MHz PW RFR at 39°C. RFR does not induce DNA repair under these exposure conditions. In preliminary experiments - with the tissue culture medium maintained at 39°C and RFR exposures (PW) at the frequencies of 350, 850, and 1200 MHz - no effect on incorporation of [³H]thymidine into DNA undergoing semiconservative synthesis was observed.