Study type: Medical/biological study (experimental study)

Microwaves modify thermoregulatory behavior in squirrel monkey med./bio.

By: Adair ER, Adams BW
Published in: Bioelectromagnetics 1980; 1 (1): 1-20
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Aim of study (acc. to author)

Squirrel monkeys trained to regulate environmental temperature behaviorally were irradiated in the far field of 2450 MHz continuous wave microwaves. The monkeys learned to control the temperature of the circulating chamber air by selecting between cold (15°C) and warm (55°C) air sources.
The aim of the study was to determine 1) the minimal incident power density that will reliably alter the ongoing thermoregulatory behavior of monkeys, 2) the nature of the alteration, and 3) the degree to which this effect may be attributed to peripheral heating. Controls included exposure to infrared radiation equivalent incident energy and no irradiation exposure.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 2.45 GHz
Modulation type: CW
Exposure duration: 10 min
  • power density: 10 W/m² minimum (2 mW/cm², 4 mW/cm², 6 mW/cm², 8 mW/cm² and 10 mW/cm²)
Exposure 2: 2.45 GHz
Modulation type: CW
Exposure duration: 10 min
  • power density: 80 W/m² minimum (10 mW/cm², 12 mW/cm², 15 mW/cm², 18 mW/cm² and 22 mW/cm²)

Exposure 1

Main characteristics
Frequency 2.45 GHz
Charakteristic
Exposure duration 10 min
Modulation
Modulation type CW
Exposure setup
Exposure source
Distance between exposed object and exposure source 1.85 m
Chamber Anechoic chamber/ 1.83 m x 1.83 m x 2.45 m
Setup Monkeys were retrained in a chair which was mounted on a TV antenna rotor
Additional info A valve system allowed air from one of two closely regulated sources to circulate through the chamber. The monkey was trained to pull a cord to operate the valves hence it was able to select the air temperature between 15 to 55°C. During exposure the preferred temperature by the monkey was 35-36°C. Control animals were exposed to 10 min of infrared radiation to same the intensities as used for microwave exposure.
Parameters
Measurand Value Type Method Mass Remarks
power density 10 W/m² minimum measured - 2 mW/cm², 4 mW/cm², 6 mW/cm², 8 mW/cm² and 10 mW/cm²
Additional parameter details

A Narda field probe was positioned in the center of the chair at the location of the monkeys head. The corresponding SAR for power densities between 1 to 22 mW/cm² derived from temperature increaments in saline-filled models ranged between 0.15 to 3.25 W

Exposure 2

Main characteristics
Frequency 2.45 GHz
Charakteristic
Exposure duration 10 min
Modulation
Modulation type CW
Exposure setup
Exposure source
Distance between exposed object and exposure source 1.85 m
Parameters
Measurand Value Type Method Mass Remarks
power density 80 W/m² minimum measured - 10 mW/cm², 12 mW/cm², 15 mW/cm², 18 mW/cm² and 22 mW/cm²

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • during exposure

Main outcome of study (acc. to author)

Most monkeys selected an environmental temperature of 34-36°C. 10-minute exposures to 2450 MHz continuous wave microwaves at an incident power density of 6-8 mW/cm² stimulated all monkeys to select a lower environmental temperature. This threshold energy represents a whole-body SAR of 1.1 W/kg. Thermoregulatory behavior was highly efficient: skin and rectal temperatures remained stable, even at 22 mW/cm² where the preferred environmental temperature was lowered by as much as 4°C. No comparable reduction in selected environmental temperature below control levels occurred during exposure to infrared radiation of equal incident power density.

Study character:

Study funded by

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