Study type: Medical/biological study (experimental study)

Studies on blood-brain barrier permeability after microwave-radiation med./bio.

By: Merritt JH, Chamness AF, Allen SJ
Published in: Radiat Environ Biophys 1978; 15 (4): 367-377
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Aim of study (acc. to editor)

To replicate previously reported results of increased permeability of blood-brain barrier by pulsed 1.2 GHz irradiation (Frey et al. 1975) and pulsed or continuous wave 1.3 GHz irradiation (Oscar and Hawkins 1977) in rats.

Background/further details

The data were compared with data of animals made hyperthermic in a warm-air environment.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 1.2 GHz
Modulation type: pulsed
Exposure duration: continuous; 30 min
  • power density: 20 W/m² peak value (15 mW/cm², 25 mW/cm² and 75 mW/cm²)
Exposure 2: 1.3 GHz
Modulation type: pulsed
Exposure duration: continuous for 20 min
  • power density: 20 W/m² peak value (15 mW/cm², 25 mW/cm² and 75 mW/cm²)
Exposure 3: 1.3 GHz
Modulation type: CW
Exposure duration: continuous for 35 min
  • power density: 1 W/m² peak value (1 mW/cm², 10 mW/cm² and 50 mW/cm²)

Exposure 1

Main characteristics
Frequency 1.2 GHz
Type
Waveform
Exposure duration continuous; 30 min
Modulation
Modulation type pulsed
Pulse width 500 ns
Packets per second 1,000
Exposure setup
Exposure source
Chamber anechoic chamber
Setup rats were anesthetized with sodium pentobarbital and positioned on styrofoam block in front of horn
Parameters
Measurand Value Type Method Mass Remarks
power density 20 W/m² peak value measured - 15 mW/cm², 25 mW/cm² and 75 mW/cm²

Exposure 2

Main characteristics
Frequency 1.3 GHz
Type
Waveform
Polarization
Exposure duration continuous for 20 min
Modulation
Modulation type pulsed
Pulse width 10 µs
Packets per second 1,000
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
power density 20 W/m² peak value measured - 15 mW/cm², 25 mW/cm² and 75 mW/cm²

Exposure 3

Main characteristics
Frequency 1.3 GHz
Type
Waveform
Polarization
Exposure duration continuous for 35 min
Modulation
Modulation type CW
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
power density 1 W/m² peak value measured - 1 mW/cm², 10 mW/cm² and 50 mW/cm²

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

Microwave irradiation of rats did not increase the permeability of the blood-brain barrier. High-power irradiation increased the brain and rectal temperature. Animals made hyperthermic in a warm environment showed increased permeability of the blood-brain barrier. Thus, previously reported findings could not be replicated.

Study character:

Study funded by

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