Study type: Medical/biological study (experimental study)

Observing-responses of rats exposed to 1.28- and 5.62-GHz microwaves med./bio.

By: de Lorge JO, Ezell CS
Published in: Bioelectromagnetics 1980; 1 (2): 183-198
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Aim of study (acc. to author)

To produce observing- and detecting behavior in rats exposed to microwaves.

Background/further details

Depression of one lever produced one of two different tones and the other lever produced food pellets when depressed in the presence of the appropriate tone. The purpose of these experiments was to discover the power density at which animals working on a vigilance task exhibit behavioral disruption when exposed at two different frequencies (1.28 and 5.62 GHz).

Endpoint

Exposure

Exposure Parameters
Exposure 1: 1.28 GHz
Modulation type: pulsed
Exposure duration: repeated daily exposure, 40 min /session, 1 session per day, 5 days/week; 62 sessions altogather
  • power density: 10 W/m² minimum (5.5 mW/cm², 9.5 mW/cm², 10 mW/cm² and 15 mW/cm²)
Exposure 2: 5.62 GHz
Modulation type: pulsed
Exposure duration: repeated daily exposure, 40 min/session, 1 session/day, 5 day/week; 183 Sessions altogather
  • power density: 75 W/m² minimum (11.5 mW/cm², 16 mW/cm², 26 mW/cm², 31.5 mW/cm², 38.5 mW/cm², 42 mW/cm² and 48.5 mW/cm²)

Exposure 1

Main characteristics
Frequency 1.28 GHz
Type
Waveform
Charakteristic
Exposure duration repeated daily exposure, 40 min /session, 1 session per day, 5 days/week; 62 sessions altogather
Modulation
Modulation type pulsed
Pulse width 3 µs
Repetition frequency 370 Hz
Exposure setup
Exposure source
Chamber microwave anechoic exposure chamber 3.40 x 2.20 x 2.35m, absorber-lined, styrofoam box 30 x 25.5 x.20 cm dxlxw
Setup The right side of the animal was irradiated while the animal was level responding
Additional info Horizontal propagation was used with the E-vector vertically polarized.
Parameters
Measurand Value Type Method Mass Remarks
power density 10 W/m² minimum measured - 5.5 mW/cm², 9.5 mW/cm², 10 mW/cm² and 15 mW/cm²
Additional parameter details

In chamber: 100 and 25 W lamp, TV camera, speakers different power densities by different distances and puls durations. Average SAR calculated from temperature measurements on water model and normalized power density were 0.25 +/- 0.01(W/kg)/1(mW/cm²)

Exposure 2

Main characteristics
Frequency 5.62 GHz
Type
Waveform
Charakteristic
Exposure duration repeated daily exposure, 40 min/session, 1 session/day, 5 day/week; 183 Sessions altogather
Additional info All exposures took place in the far field except 16mW/cm²
Modulation
Modulation type pulsed
Pulse width 500 ns
Repetition frequency 662 Hz
Additional info

0.5 or 2 µs pulse duration
Exposure setup
Exposure source
Chamber microwave anechoic exposure chamber 2.54 x 1.94 x 2.43 m, absorber-lined, styrofoam box 30 x 25.5 x.20 cm dxlxw
Parameters
Measurand Value Type Method Mass Remarks
power density 75 W/m² minimum measured - 11.5 mW/cm², 16 mW/cm², 26 mW/cm², 31.5 mW/cm², 38.5 mW/cm², 42 mW/cm² and 48.5 mW/cm²
Additional parameter details

In chamber: 100 and 25 W lamp, TV camera, speakers. Average SAR calculated from temperature measurements on water model and normalized power density were 0.19 +/- 0.03(W/kg)/1(mW/cm²)

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • during exposure

Main outcome of study (acc. to author)

At 5.62 GHz, the observing-response rate was not consistently affected until the power density approximated 26 mW/cm². At 1.28 GHz, the observing-response rate of all animals was consistently affected at a power density of 15 mW/cm². Measurements of localized SAR values in a rat-shaped model of simulated muscle tissue revealed marked differences in the absorption pattern between the two frequencies. It is concluded that the animal's observing behavior is disrupted at a lower power density at 1.28 than at 5.62 GHz because of deeper penetration of energy at the lower frequency, and because of frequency-dependent differences in anatomic distribution of the absorbed microwave energy.

Study character:

Study funded by