ID Number		941
Study Type		In Vivo
Model		2450, 2800 MHz (CW, PW) exposures to rats and analysis of behavioral responses
Details		Long Evans and albino rats were exposed to 2450 MHz (CW or PW- 2 usec pulse width, 500 Hz pulse repetition rate) at SARs of between 0.1-2 W/kg for 30-60 minutes in combination with chlordiazepoxide hydrochloride and analyzed for fixed interval behavior (pressing a small lever to produce a food pellet). MW exposure alone at 1-2 W/kg increased error rates, time-outs, and pausing between responses, and decreased completion rates in a fixed interval behavioral test. In subsequent studies using the above exposure regimen at SARs of ~0.2 W/kg, with rats undergoing 4 months of prior training before the exposure study, microwave exposure alone had no effect on behavior response time, but in combination with chlordiazepoxide hydrochloride enhanced by 2-fold the drug induced increase in lever pressing response rate at doses up to 5 mg/kg and similarly enhanced by 2-fold the drug induced decrease in lever pressing response time at doses above 5 mg/kg. In a similar study, conditioned rats were exposed as above in combination with dextroamphetamine (DAP) and analyzed for comparable behavioral responses. In this study the investigators also included multiple exposures for 30 min/day, 4 days/wk. Again the MW exposure enhanced the effects of DAP similar to the effect with chlordiazepoxide hydrochloride. The authors suggest microwave exposure can potentiate the effect of drugs although inducing no behavioral effects alone. In other studies, rats were exposed to 2.8 GHz (CW or PW-2 usec pulse width, 500 Hz pulse repetition frequency) MW for 30 minutes at power densities up to 15 mW/cm2 to determine the threshold for effects and compare the effects of PW vs CW MW exposures. Following exposure at 10-15 mW/cm2 to PW, but not CW, effects on the number of correctly timed behavioral responses (although inconsistent increases and decreases) were observed. The authors suggest brief exposure to low-intensity pulsed microwaves may potentiate the effect of drugs even at levels below those required to produce behavioral effects alone.
Findings		Effects
Status		Completed With Publication
Principal Investigator		Naval Medical Res. Inst., MD, USA
Funding Agency		Navy, USA
Country		UNITED STATES
References		Thomas, JR et al. Bioelectromagnetics, (1982) 3:227-235 Schrot, J et al. Bioelectromagnetics, (1980) 1:89-99 Thomas, JR et al. Neurobehav. Toxicol., (1980) 2:131-135 Thomas, JR et al. Science, (1979) 203:1357-1358 Thomas, JR Radio Sci., (1979) 14:253-258 Thomas, JR et al. BIOLOGICAL EFFECTS OF ELECTROMAGNETIC WAVES, (1975) :201-214 Thomas, JR et al. Ann. N.Y. Acad. Sci., (1975) 247:425-432
Comments		From Chou et al ( Bioelectromagnetics 1985, 6:323-326), using the same 2450 MHz carrier signal with a similar PW modulation (2 usecond pulse width, 1 millisecond pulse duration), the threshold for microwave hearing would be 0.75 – 1.5 W/cm2. The Thomas studies had a peak power of 1 W/cm2, making microwave hearing a real possibility. This is further supported in the groups studies that showed an effect with PW but no effect with CW exposure.