MEASUREMENT OF DNA-DAMAGE ALTER EXPOSURE TO 2450 MHZ ELECTROMAGNETIC-RADIATION

Recent reports suggest that exposure to 2450 MHz electromagnetic radia tion causes DNA single-strand breaks (SSBs) and double-strand breaks ( DSBs) in cells of rat brain irradiated in vivo (Lai and Singh, Bioelec tromagnetics 16, 207-210, 1995; Int. J. Radiat. Biol. 69, 513-521, 199 6). Therefore, we endeavored to determine if exposure of cultured mamm alian cells in vitro to 2450 MHz radiation causes DNA damage. The alka line comet assay (single-cell gel electrophoresis), which is reportedl y the most sensitive method to assay DNA damage in individual cells, w as used to measure DNA damage after in vitro 2450 MHz irradiation. Exp onentially growing U87MG and C3H 10T1/2 cells were exposed to 2450 MHz continuous-wave (CW) radiation in specially designed radial transmiss ion lines (RTLs) that provided relatively uniform microwave exposure. Specific absorption rates (SARs) were calculated to be 0.7 and 1.9 W/k g. Temperatures in the RTLs were measured in real time and were mainta ined at 37 +/- 0.3 degrees C. Every experiment included sham exposure( s) in an RTL. Cells were irradiated for 2 h, 2 h followed by a 4-h inc ubation at 37 degrees C in an incubator, 4 h and 24 h. After these tre atments samples were subjected to the alkaline comet assay as describe d by Olive et al. (Exp. Cell Res. 198, 259-267, 1992). Images of comet s were digitized and analyzed using a PC-based image analysis system, and the ''normalized comet moment'' and ''comet length'' were determin ed. No significant differences were observed between the test group an d the controls after exposure to 2450 MHz CW irradiation. Thus 2450 MH z irradiation does not appear to cause DNA damage in cultured mammalia n cells under these exposure conditions as measured by this assay. (C) 1997 by Radiation Research Society.