Study type: Medical/biological study (experimental study)

Thermal and physiological responses of rats exposed to 2.45-GHz radiofrequency radiation: a comparison of E and H orientation. med./bio.

Published in: Radiat Environ Biophys 1989; 28 (3): 235-246

Aim of study (acc. to author)

To compare the effects of acute exposure to 2.45 GHz radiofrequency irradiation in E-orientation (long axis of body parallel to electric field) and H-orientation (long axis of body parallel to magnetic field) upon the patterns of heat distribution, the overall heating and cooling responses, and changes in cardiovascular and respiratory function in anesthetized rats.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 2.45 GHz
Modulation type: CW
Exposure duration: intermittent*
Exposure 2: 2.45 GHz
Modulation type: CW
Exposure duration: intermittent*

General information

*The exposure was discontinued when the colonic temperature increased to 39.5°C and it was initiated again when the temperature returned to 38.5°C. This procedure was continued for 3 cycles

Exposure 1

Main characteristics
Frequency 2.45 GHz
Type
Charakteristic
Polarization
Exposure duration intermittent*
Additional info Animals were exposed in E orientation (long axis of their body parallel electric field)
Modulation
Modulation type CW
Exposure setup
Exposure source
Distance between exposed object and exposure source 0.0015 m
Chamber Eccosorb RF-shielded anechoic chamber
Setup Rats placed on a holder
Additional info The rise time and the recovery time were 8.6 ± 0.4 and 16.6 ± 1.3 min respectively The holder consisted of seven 0.5 cm (O.D) Plexiglas rods mounted in a semicircular pattern on 4 cm x 6 cm Plexiglas plates (0.5 cm thick)
Parameters
Measurand Value Type Method Mass Remarks
power density 600 W/m² mean measured - corresponding whole body average SAR was 14.5 ± 2.2 W/kg

Exposure 2

Main characteristics
Frequency 2.45 GHz
Type
Charakteristic
Polarization
Exposure duration intermittent*
Additional info Animals exposed in H orientation (magnetic field parallel to the long axis of the animal)
Modulation
Modulation type CW
Exposure setup
Exposure source
Distance between exposed object and exposure source 0.0015 m
Chamber Eccosorb RF-shielded anechoic chamber
Setup Rats placed on a holder
Additional info The rise time and the recovery time were 8.0 ± 0.2 and 15.2 ± 1.1 min respectively The holder consisted of seven 0.5 cm (O.D) Plexiglas rods mounted in a semicircular pattern on 4 cm x 6 cm Plexiglas plates (0.5 cm thick)
Parameters
Measurand Value Type Method Mass Remarks
power density 600 W/m² mean measured - corresponding whole body average SAR was 12.4 ± 2.6 W/kg

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Investigated organ system:
Time of investigation:
  • during exposure

Main outcome of study (acc. to author)

The pattern of heat distribution within the rat and the physiological responses were significantly different between E- and H-orientation irradiation. Exposure in E-orientation resulted in greater peripheral and tympanic heating, while exposure in H-orientation resulted in greater body core heating.
Heart rate and blood pressure increased significantly during exposure and returned to baseline levels when irradiation was discontinued; the increases were significantly greater in E- than in H-orientation. Respiratory rate increased significantly during exposure in H-, but not in E-orientation.
The physiological responses could have been influenced by the different levels or rates of subcutaneous and tympanic heating, or the differential between body core and peripheral heating during E- and H-orientation exposure.

Study character:

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