Primary DNA damage in human blood lymphocytes exposed in vitro to 2450 MHzradiofrequency radiation

Human peripheral blood samples collected from three healthy human volunteer s were exposed in vitro to pulsed-wave 2450 MHz radiofrequency (RF) radiati on for 2 h, The RF radiation was generated with a net forward power of 21 W and transmitted from a standard gain rectangular antenna horn in a vertica lly downward direction. The average power density at the position of the ce lls in the flask was 5 mW/cm(2). The mean specific absorption rate, calcula ted by finite difference time domain analysis, was 2.135 (+/-0.005 SE) W/kg . Aliquots of whole blood that were sham-exposed or exposed in vitro to 50 cGy of ionizing radiation from a Cs-137 gamma-ray source were used as contr ols. The lymphocytes were examined to determine the extent of primary DNA d amage (single-strand breaks and alkali-labile lesions) using the alkaline c omet assay with three different slide-processing schedules, The assay was p erformed on the cells immediately after the exposures and at 4 h after incu bation of the exposed blood at 37 +/- 1 degrees C to allow time for rejoini ng of any strand breaks present immediately after exposure, i.e. to assess the capacity of the lymphocytes to repair this type of DNA damage. At eithe r time, the data indicated no significant differences between RF-radiation- and sham-exposed lymphocytes with respect to the comet tail length, fluore scence intensity of the migrated DNA in the tail, and tail moment. The conc lusions were similar for each of the three different comet assay slide-proc essing schedules examined. In contrast, the response of lymphocytes exposed to ionizing radiation was significantly different from RF-radiation- and s ham-exposed cells. Thus, under the experimental conditions tested, there is no evidence for induction of DNA single-strand breaks and alkali-labile le sions in human blood lymphocytes exposed in vitro to pulsed-wave 2450 MHz r adiofrequency radiation, either immediately or at 4 h after exposure, (C) 2 000 by Radiation Research Society.