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.