Study type: Medical/biological study (experimental study)

Acute low-level microwave exposure and central cholinergic activity: studies on irradiation parameters. med./bio.

Published in: Bioelectromagnetics 1988; 9 (4): 355-362

Aim of study (acc. to author)

To measure sodium-dependent high-affinity choline uptake in the brain of rats after acute exposure to pulsed or continuous wave (CW) 2450 MHz microwaves. In addition the effects of microwave exposure in two exposure systems (the cylindrical waveguide and the miniature anechoic chamber) are compared.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 2,450 MHz
Modulation type: pulsed, CW
Exposure duration: continuous for 45 min
Exposure 2: 2,450 MHz
Modulation type: pulsed, CW
Exposure duration: continuous for 45 min

General information

Rats were exposed to pulsed or CW microwaves in either a cylindrical waveguide system or a miniature anechoic chamber.

Exposure 1

Main characteristics
Frequency 2,450 MHz
Type
Charakteristic
  • guided field
Polarization
  • circular
Exposure duration continuous for 45 min
Modulation
Modulation type pulsed, CW
Pulse width 2 µs
Repetition frequency 500 Hz
Additional info

pulsed or CW

Exposure setup
Exposure source
Chamber The cylindrical waveguide system [Guy et al., 1979] consisted of four individual exposure tubes consisting of a section of circular waveguide made of galvanized wire screen. The circularly polarised field in TE11 mode propagated perpendicular to the longitudinal axis of the rat housed in a plastic chamber with a floor of glass rods.
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 0.6 W/kg average over mass - whole body -
power density 1 mW/cm² - - - -

Exposure 2

Main characteristics
Frequency 2,450 MHz
Type
Polarization
Exposure duration continuous for 45 min
Modulation
Modulation type pulsed, CW
Pulse width 2 µs
Repetition frequency 500 Hz
Additional info

pulsed or CW

Exposure setup
Exposure source
Chamber The miniature anechoic chamber [Guy, 1979] was made of thick stock hardboard panels lined inside with RF absorbing materials. A standard-gain horn antenna mounted at the tapered roof of the chamber provided plane-polarised irradiation. A plastic animal cage was placed on a Styrofoam platform such that its long axis was parallel to the electric field.
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 0.6 W/kg average over mass - whole body -
power density 2.07 mW/cm² - - - -

Reference articles

  • Chou CK et al. (1985): Specific absorption rate in rats exposed to 2,450-MHz microwaves under seven exposure conditions.
  • Guy AW et al. (1979): Circularly polarized 2450 MHz waveguide system for chronic exposure of small animals to microwaves.
  • Guy AW (1979): Miniature anechoic chamber for chronic exposure of small animals to plane-wave microwave fields.

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

1) The effects on frontal cortical choline uptake are independent of the irradiation system or use of pulsed or continuous wave (CW) microwaves. Decrease in choline uptake was observed in the frontal cortex after microwave irradiation in all of the above exposure conditions. 2) The hippocampal choline uptake decreased after pulsed but not after continuous wave (CW) microwave exposure. 3) The effects on striatal choline uptake depend on the exposure system used. Choline uptake was decreased after irradiation to either pulsed or continuous wave (CW) microwaves in the miniature anechoic chamber. 4) The irradiation to microwaves under the present conditions had no effect on hypothalamic choline uptake.
The results suggest that the biological effects of microwaves can depend on the parameter of the irradiation.

Study character:

Study funded by

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