Thermoregulatory responses of rats exposed to 9.3-GHz microwaves: a comparison of E and H orientation.
The purpose of this study was to determine the effects of exposure orientation relative to electric and magnetic fields (E and H fields) on the thermal, cardiovascular, and respiratory changes in ketamine-anesthetized rats exposed to far-field, continuous-wave, 9.3-GHz radiofrequency radiation (RFR). Irradiation (specific absorption rate = 12.5 W/kg in both orientations; power levels of 79 and 59 mW/cm2 in E and H orientations, respectively) was conducted to produce 1 degree C colonic temperature changes (38.5 to 39.5 degrees C). During experimentation, arterial blood pressure and respiratory rate, colonic (Tc) tympanic (Tt) left and right subcutaneous (Tsl & Tsr) (sides toward and away from RFR source), and tail temperatures (Tta) were continuously recorded. The Tsr change during E-orientation exposure was considerably less than the Tc change; the Tt and Tsr (H-orientation) changes approximated the Tc increase; and the Tsl and Tta changes (both orientations) were considerably greater than the Tc increase. The Tt and Tsl increases were virtually equal under the two exposure conditions; however, the Tsr increase was significantly greater during H-orientation irradiation, and the Tta increase was significantly greater during E-orientation exposure. Heart rate and mean arterial pressure increased significantly during irradiation; however the cardiovascular responses were not affected by exposure orientation. The latter findings at 9.3 GHz contrast with the marked cardiovascular response differences between E- and H-orientation exposure noted during previous studies at 0.7 to 2.45 GHz.
Frei
M R
MR
Radiofrequency Radiation Branch, US Air Force Armstrong Laboratory, Brooks Air Force Base, Texas 78235.
Jauchem
J R
JR
D000818:Animals; D001794:Blood Pressure / Q000528:radiation effects; D001831:Body Temperature / Q000528:radiation effects; D001833:Body Temperature Regulation / Q000528:radiation effects*; D004560:Electricity; D006339:Heart Rate / Q000528:radiation effects; D008280:Magnetics; D008297:Male; D008872:Microwaves; D011846:Radio Waves; D051381:Rats; D011919:Rats, Inbred Strains; D012119:Respiration / Q000528:radiation effects