To examine possible combined effects of radiofrequency exposure with other agents, cells were treated with menadione to induce reactive oxygen species, and with tertiary butylhydro-peroxide to induce lipid peroxidation. The experiments were performed isothermal and with a specific absorption rate of 5 W/kg which is obviously above the ICNIRP limit value.
|Chamber||CO2 (5%) and temperature-controlled air were provided to the aluminium RF resonator by ventilation from a cell culture incubator. Temperature increases in the cell cultures were eliminated by placing the culture dishes on a heat exchanger with water circulation, which ensured isothermal conditions (37.0 ± 0.3°C).|
|Setup||Cells in two 55-mm glass or plastic Petri dishes were RF exposed in one chamber, and two dishes were simultaneously sham-exposed in an identical chamber.|
|Sham exposure||A sham exposure was conducted.|
|Additional info||The cells were subjected to four conditions: no exposure, RF radiation, chemical treatment, and RF radiation plus chemical treatment.|
The lipid peroxidation induced by tertiary butylhydro-peroxide was statistically significant increased in radio frequency exposed human neuroblastoma cells, but not in radio frequency exposed mouse fibroblasts. Additionally, menadione-induced caspase 3 activity was statistically significant increased in radio frequency exposed mouse fibroblasts, but not in radio frequency exposed human neuroblastoma cells. Both differences were statistically significant only for the GSM-modulated signal. The other endpoints were not significantly affected in any of the experimental conditions, and no effects were observed from exposure to radio frequency irradiation alone.
The authors conclude that the positive findings may be due to chance, but they may also reflect effects that occur only in cells sensitized by chemical stress. Further studies are required to investigate the reproducibility and dose response of the possible effects.