Study type: Medical/biological study (experimental study)

Permeability of the blood-brain barrier induced by 915 MHz electromagnetic radiation, continuous wave and modulated at 8, 16, 50, and 200 Hz. med./bio.

Published in: Microsc Res Tech 1994; 27 (6): 535-542

Aim of study (acc. to author)

To study the permeability of blood-brain barrier to endogenous albumin and fibrinogen during exposure to microwaves of 915 MHz as continuous wave and pulse-modulated at the various repetition rates.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 915 MHz
Modulation type: CW
Exposure duration: continuous for 2 h
Exposure 2: 915 MHz
Modulation type: pulsed
Exposure duration: continuous for 2 h
  • power: 20 W peak value (2-20 W)
  • SAR: 0.016 W/kg
  • SAR: 0.04 W/kg
  • SAR: 0.08 W/kg
  • SAR: 0.16 W/kg
Exposure 3: 915 MHz
Modulation type: pulsed
Exposure duration: continuous for 2 h
Exposure 4: 915 MHz
Modulation type: pulsed
Exposure duration: continuous for 2 h
Exposure 5: 915 MHz
Modulation type: pulsed
Exposure duration: continuous for 2 h

Exposure 1

Main characteristics
Frequency 915 MHz
Type
Charakteristic
  • guided field
Exposure duration continuous for 2 h
Modulation
Modulation type CW
Exposure setup
Exposure source
Chamber The TEM cell was enclosed in a well ventilated wooden box supporting the outer conductor made of brass-net and the central plate, or septum, constructed of aluminium and held up by Teflon braces.
Setup Unanaesthetized rats were placed in the upper and lower compartments of the TEM cell.
Parameters
Measurand Value Type Method Mass Remarks
power 3 W - - - 0.2-3 W
SAR 0.3 W/kg - estimated brain -
SAR 1.7 W/kg - estimated brain -
SAR 3.3 W/kg - estimated brain -
SAR 5 W/kg - estimated brain -

Exposure 2

Main characteristics
Frequency 915 MHz
Type
Charakteristic
  • guided field
Exposure duration continuous for 2 h
Modulation
Modulation type pulsed
Pulse width 0.57 ms
Repetition frequency 8 Hz
Pulse type rectangular
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
power 20 W peak value - - 2-20 W
SAR 0.016 W/kg - estimated brain -
SAR 0.04 W/kg - estimated brain -
SAR 0.08 W/kg - estimated brain -
SAR 0.16 W/kg - estimated brain -

Exposure 3

Main characteristics
Frequency 915 MHz
Type
Charakteristic
  • guided field
Exposure duration continuous for 2 h
Modulation
Modulation type pulsed
Pulse width 0.57 ms
Repetition frequency 16 Hz
Pulse type rectangular
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
power 20 W peak value - - 2-20 W
SAR 0.03 W/kg - estimated brain -
SAR 0.08 W/kg - estimated brain -
SAR 0.15 W/kg - estimated brain -
SAR 0.3 W/kg - estimated brain -
SAR 2.1 W/kg - estimated brain at 4 ms pulse width and 20 W in pulse

Exposure 4

Main characteristics
Frequency 915 MHz
Type
Charakteristic
  • guided field
Exposure duration continuous for 2 h
Modulation
Modulation type pulsed
Pulse width 4 ms
Repetition frequency 50 Hz
Pulse type rectangular
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
power 20 W peak value - - 1-20 W
SAR 0.3 W/kg - estimated brain -
SAR 0.7 W/kg - estimated brain -
SAR 1.7 W/kg - estimated brain -
SAR 3.3 W/kg - estimated brain -
SAR 5 W/kg - estimated brain at 6 ms pulse width and 10 W in pulse
SAR 1 W/kg - estimated brain at 0.57 ms pulse width and 20 W in pulse

Exposure 5

Main characteristics
Frequency 915 MHz
Type
Charakteristic
  • guided field
Exposure duration continuous for 2 h
Modulation
Modulation type pulsed
Pulse width 0.57 ms
Repetition frequency 200 Hz
Pulse type rectangular
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
power 10 W peak value - - 2-10 W
SAR 0.4 W/kg - estimated brain -
SAR 1 W/kg - estimated brain -
SAR 2.1 W/kg - estimated brain -
SAR 2.9 W/kg - estimated brain at 4 ms pulse width and 2 W in pulse

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

Exposed animals are at risk concerning opening of the blood-brain barrier and the response is independent of pulse repetition rate. The response is the same for continuous wave as compared with pulse modulation. The response is independent of SAR in the interval 0.016 < SAR < 2.5 W/kg, but rises for SAR > 2.5 W/kg.

Study character:

Study funded by

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