CHARACTERISTICS OF MICROWAVE EVOKED BODY MOVEMENTS IN MICE

Microwave evoked body movements were studied in mice. A resonant cavit y was used to provide head and neck exposure of the mouse to pulsed an d gated continuous wave (CW) 1.25 GHz microwaves. No difference in res ponse to pulsed and gated CW stimuli of equal average power was found. The incidence of the microwave evoked body movements increased propor tionally with specific absorption (dose) when the whole-body average s pecific absorption rate was at a constant level (7300 W/kg). Under a c onstant average specific absorption rate, the response incidence reach ed a plateau at 0.9 kJ/kg. For doses higher than 0.9 kJ/kg, response i ncidence was proportional to the specific absorption rate and reached a plateau at 900 W/kg. Body movements could be evoked by a single micr owave pulse. The lowest whole-body specific absorption (SA) tested was 0.18 kJ/kg, and the corresponding brain SA was 0.29 kl/kg. Bulk heati ng potentials of these SAs were less than 0.1-degrees-C. For doses hig her than 0.9 kJ/kg, the response incidence was also proportional to su bcutaneous temperature increment and subcutaneous heating rate. The ex trapolated absolute thresholds (0% incidence) were 1.21-degrees-C temp erature increment and 0.24-degrees-C/s heating rate. Due to high subcu taneous heating rates, these microwaves must be perceived by the mouse as an intense thermal sensation but not a pain sensation because the temperature increment was well below the threshold for thermal pain. R esults of the present study should be considered in promulgation of pe rsonnel protection guideline against high peak power but low average p ower microwaves. (C) 1994 Wiley-Li,s, Inc.