Study type: Medical/biological study (experimental study)

Blood-brain barrier permeability in rats exposed to electromagnetic fields used in wireless communication med./bio.

By: Persson BRR, Salford L, Brun A
Published in: Wirel Netw 1997; 3 (6): 455-461
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Aim of study (acc. to author)

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

Endpoint

Exposure

Exposure Parameters
Exposure 1: 915 MHz
Modulation type: CW
Exposure duration: continuous for 2 min to 960 min
  • SAR: 0.08 W/kg average over mass (whole body) (0.02-0.08 W/kg)
  • SAR: 0.95 W/kg average over mass (whole body) (0.11-0.95 W/kg)
  • SAR: 8.3 W/kg average over mass (whole body) (1.7-8.3 W/kg)
Exposure 2: 915 MHz
Modulation type: pulsed
Exposure duration: continuous for 2 min to 960 min
  • SAR: 8 mW/kg average over mass (whole body) (0.4-8 mW/kg)
  • SAR: 0.08 W/kg average over mass (whole body) (0.02-0.08 W/kg)
  • SAR: 0.95 W/kg average over mass (whole body) (0.11-0.95 W/kg)
  • SAR: 8.3 W/kg average over mass (whole body) (1.7-8.3 W/kg)
Exposure 3: 915 MHz
Modulation type: pulsed
Exposure duration: continuous for 2 min to 960 min
  • SAR: 8 mW/kg average over mass (whole body) (0.4-8 mW/kg)
  • SAR: 0.08 W/kg average over mass (whole body) (0.02-0.08 W/kg)
  • SAR: 0.95 W/kg average over mass (whole body) (0.11-0.95 W/kg)
  • SAR: 8.3 W/kg average over mass (whole body) (1.7-8.3 W/kg)
Exposure 4: 915 MHz
Modulation type: pulsed
Exposure duration: continuous for 2 min to 960 min
  • SAR: 8 mW/kg average over mass (whole body) (0.4-8 mW/kg)
  • SAR: 0.08 W/kg average over mass (whole body) (0.02-0.08 W/kg)
  • SAR: 0.95 W/kg average over mass (whole body) (0.11-0.95 W/kg)
  • SAR: 8.3 W/kg average over mass (whole body) (1.7-8.3 W/kg)
Exposure 5: 915 MHz
Modulation type: pulsed
Exposure duration: continuous for 2 min to 960 min
  • SAR: 8 mW/kg average over mass (whole body) (0.4-8 mW/kg)
  • SAR: 0.08 W/kg average over mass (whole body) (0.02-0.08 W/kg)
  • SAR: 0.95 W/kg average over mass (whole body) (0.11-0.95 W/kg)
Exposure 6: 915 MHz
Modulation type: pulsed
Exposure duration: continuous for 2 min to 960 min
  • SAR: 8 mW/kg average over mass (whole body) (0.4-8 mW/kg)

General information

In each experiment, 4-6 rats with 4 controls were randomly placed in excited and non-excited TEM cells, respectively.

Exposure 1

Main characteristics
Frequency 915 MHz
Type
Charakteristic
  • guided field
Exposure duration continuous for 2 min to 960 min
Modulation
Modulation type CW
Exposure setup
Exposure source
Chamber The TEM cell was enclosed in a wooden box which supported the outer conductor and central plate. The outer conductor made of brass mesh was attached to the inner walls of the box. The central plate or septum was made of aluminium and was held up by Teflon braces which were screwed to the inner side walls.
Setup Rats were placed in plastic trays to avoid contact with the central plate and outer conductor.
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 0.08 W/kg average over mass measured and calculated whole body 0.02-0.08 W/kg
SAR 0.95 W/kg average over mass measured and calculated whole body 0.11-0.95 W/kg
SAR 8.3 W/kg average over mass measured and calculated whole body 1.7-8.3 W/kg
Measurement and calculation details

Transmitted and absorbed power was measured at CW exposure with and without rats in the TEM-cell. From these measurements the average SAR in the whole rat was calculated to be 1.2 ± 0.4 W/kg per watt of input power. This value was in good agreement with the theoretical estimate of 1.6 W/kg per watt of input power that was used in the evaluation of the experiment.

Exposure 2

Main characteristics
Frequency 915 MHz
Type
Charakteristic
  • guided field
Exposure duration continuous for 2 min to 960 min
Modulation
Modulation type pulsed
Pulse width 0.57 ms
Repetition frequency 217 Hz
Pulse type rectangular
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 8 mW/kg average over mass measured and calculated whole body 0.4-8 mW/kg
SAR 0.08 W/kg average over mass measured and calculated whole body 0.02-0.08 W/kg
SAR 0.95 W/kg average over mass measured and calculated whole body 0.11-0.95 W/kg
SAR 8.3 W/kg average over mass measured and calculated whole body 1.7-8.3 W/kg

Exposure 3

Main characteristics
Frequency 915 MHz
Type
Charakteristic
  • guided field
Exposure duration continuous for 2 min to 960 min
Modulation
Modulation type pulsed
Pulse width 6.6 ms
Repetition frequency 50 Hz
Pulse type rectangular
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 8 mW/kg average over mass measured and calculated whole body 0.4-8 mW/kg
SAR 0.08 W/kg average over mass measured and calculated whole body 0.02-0.08 W/kg
SAR 0.95 W/kg average over mass measured and calculated whole body 0.11-0.95 W/kg
SAR 8.3 W/kg average over mass measured and calculated whole body 1.7-8.3 W/kg

Exposure 4

Main characteristics
Frequency 915 MHz
Type
Charakteristic
  • guided field
Exposure duration continuous for 2 min to 960 min
Modulation
Modulation type pulsed
Repetition frequency 16 Hz
Pulse type rectangular
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 8 mW/kg average over mass measured and calculated whole body 0.4-8 mW/kg
SAR 0.08 W/kg average over mass measured and calculated whole body 0.02-0.08 W/kg
SAR 0.95 W/kg average over mass measured and calculated whole body 0.11-0.95 W/kg
SAR 8.3 W/kg average over mass measured and calculated whole body 1.7-8.3 W/kg

Exposure 5

Main characteristics
Frequency 915 MHz
Type
Charakteristic
  • guided field
Exposure duration continuous for 2 min to 960 min
Modulation
Modulation type pulsed
Repetition frequency 8.3 Hz
Pulse type rectangular
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 8 mW/kg average over mass measured and calculated whole body 0.4-8 mW/kg
SAR 0.08 W/kg average over mass measured and calculated whole body 0.02-0.08 W/kg
SAR 0.95 W/kg average over mass measured and calculated whole body 0.11-0.95 W/kg

Exposure 6

Main characteristics
Frequency 915 MHz
Type
Charakteristic
  • guided field
Exposure duration continuous for 2 min to 960 min
Modulation
Modulation type pulsed
Repetition frequency 4 Hz
Pulse type rectangular
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 8 mW/kg average over mass measured and calculated whole body 0.4-8 mW/kg

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)

It was demonstrated that microwave exposure produces an unequivocal effect on the blood-brain barrier in the exposed rats. The frequency of pathological rats was 170/481among rats exposed to pulse modulated and 74/149 among rats exposed to continuous wave exposure. The results are both significantly different to their corresponding controls and the frequency of pathological rats after exposure to pulsed radiation is significantly less than after exposure to continuous radiation.

Study character:

Study funded by

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