ID Number		484
Study Type		In Vivo
Model		915, 1250, 2450 MHz (PW) exposure to cats and rats and analysis of MW hearing and acoustic startle behavior
Details		Cats and rats were exposed to 915 and 2450 MHz RF to analyze MW hearing effects. In some studies, cats were exposed to 915 MHz (PW- pulse durations < 250 usec) RF bursts at an average temporal SAR at the midline of the skull of 0.304 - 1 W/kg (100 W/kg peak) using a diathermy applicator. The threshold of cochlear nuclei stimulation was found to be ~ 11.1 W/kg per pulse (4-40 uJ/g/pulse) using microelectrode techniques. The authors attributed this to a thermo-acoustic wave in the head stimulating the inner ear via bone conduction. To better characterize the microwave hearing phenomenon, Long Evans rats were exposed to 1.25 GHz (PW- 0.8-1.0 usec pulse duration) MW pulses at SARs of 15-30 kW/kg (low intensity) or 35-111 kW/kg (high intensity) at various times before a loud acoustic stimuli or bursts of air. To detect the MW hearing effect, a startle response paradigm was employed. Pre-exposure decreased the startle response, and prior experience to low-intensity MW pre-pulses modified the startle response latency. The authors concluded MW pulses above 0.12-16 mJ/kg (MW hearing threshold) can modify the amplitude and latency of startle response in rats to acoustic stimuli with no permanent neurological effects or changes in behavior. The author further describes a model to predict single-neuron auditory thresholds (J Bioelectr (1990) 9(2):151-157). In related studies (Bioelectromagnetics (1989) 10(2):147-160); Hear Res (1987) 26(1):105-116), dorsal cochlear neurons in anesthesized cats were monitored during head exposure to 915 MHz (PW) MW. Neurons representing the full frequency range of hearing were able to respond to low-level MW pulses at a threshold of11.1 mW/g per pulse (0.6 uJ/g). In similar studies of neuron response. In similar studies looking at the acoustic startle response in combination with chemically induced CNS neurodegeneration, Sprague Dawley rats were injected with 3-nitropropionic acid (3-NP) and exposed 1.5 hours later to 1.25 GHz (PW-5.9 usec pw at 10 Hz) at 0.6 or 6 W/kg for 30 minutes in an anechoic chamber for 2 successive days. Short term (~ 2 hours after exposure) and long-term (1-3 weeks) activity was measured. No MW effect was observed on brain histopathology or on short-term activity or basic startle response. However, there was a synergistic effect between 0.6 W/kg MW and 3-NP to reduce short-term startle PPI vs an opposing effect between 6 W/kg MW and 3-NP to increase short-term of startle PPI. In addition, no MW effect was observed on long-term activity or basic startle response, however both 0.6 & 6 W/kg MW exposure blocked long term of reduction of startle PPI by 3-NP.
Findings		Effects
Status		Completed With Publication
Principal Investigator		Brooks AFB, USA - ronald.seaman@brooks.af.mil
Funding Agency		AF, USA
Country		UNITED STATES
References		Seaman, RL et al. Physiol. Behav., (1994) 55:587-595 Seaman, RL et al. Bioelectromagnetics, (1992) 13:323-328 Seaman, RL et al. Bioelectromagnetics, (1989) 10:147-160 Seaman, RL et al. J. Microwave Power, (1978) 13:77-86 Lebovitz, RM et al. Brain Res., (1977) 126:370-375 Lebovitz, RM et al. Radio Science, (1977) 12:229-236 Lebovitz, RM et al. Symposium on Biological Effects and Measurement of Radio Frequency/Microwaves. D.G. Hazzard, editor. U.S. Department of Health, Education, and Welfare [HEW Publication (FDA) 77-8026]., (1977) :314-333 Lebovitz, RM INFLUENCE OF CHRONIC EXPOSURE TO LOW LEVEL PULSED MICROWAVE RADIATION ON PERFORMANCE AND COGNITIVE BEHAVIOR, (1983) :-
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