Study type: Medical/biological study (experimental study)

Increased permeability of the blood-brain barrier induced by magnetic and electromagnetic fields. med./bio.

Published in: Ann N Y Acad Sci 1992; 649: 356-358

Aim of study (acc. to author)

First: To study the dye permeability (Evans blue) of the blood-brain barrier after exposure to components of the MRI electromagnetic fields. Static magnetic fields, low frequency magnetic fields, radiofrequency electromagnetic fields (RF), and a combination of these three types of fields were applied to Sprague-Dawley rats in these experiments.
Second: To study the leakage of endogenous albumin and fibrinogen during exposure to microwaves of 915 MHz (CW and modulated at various low frequencies (8-215 Hz)). In these experiments Fischer 344 rats were used.

Endpoint

Exposure

Exposure Parameters
Exposure 1:
Exposure duration: continuous for 2 h
-
Exposure 2:
Modulation type: pulsed
Exposure duration: continuous for 2 h
Exposure 3:
Modulation type: pulsed
Exposure duration: continuous for 2 h
Exposure 4: 915 MHz
Modulation type: CW
Exposure 5: 915 MHz
Modulation type: pulsed
Exposure 6:
Exposure duration: continuous for 1 h

Exposure 1

Main characteristics
Frequency
Type
Waveform
Exposure duration continuous for 2 h
Additional info low frequency pulsed magnetic field (TVMF)
Modulation
Modulation type unspecified
Exposure setup
Exposure source
Parameters

No parameters are specified for this exposure.

Exposure 2

Main characteristics
Frequency
Type
Exposure duration continuous for 2 h
Additional info RF electromagnetic field (RF)
Modulation
Modulation type pulsed
Repetition frequency 1 Hz
Additional info

pulse width of 400 to 800 ms

Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
power 0.2 W - - - -

Exposure 3

Main characteristics
Frequency
Type
Waveform
Exposure duration continuous for 2 h
Additional info SMF + TVMF + RF
Modulation
Modulation type pulsed
Repetition frequency 1 Hz
Additional info

pulse width of 400 to 800 ms

Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 0.08 T - - - SMF
power 0.2 W - - - RF

Exposure 4

Main characteristics
Frequency 915 MHz
Type
Charakteristic
  • guided field
Modulation
Modulation type CW
Exposure setup
Exposure source
Additional info Rats were not anaesthetized during the exposure.
Parameters
Measurand Value Type Method Mass Remarks
power 3 W - - - -

Exposure 5

Main characteristics
Frequency 915 MHz
Type
Charakteristic
  • guided field
Modulation
Modulation type pulsed
Additional info

pulse rates of 8, 16, 50, and 215 Hz pulse widths of 0.6 to 4 ms

Exposure setup
Exposure source
Additional info Rats were not anaesthetized during the exposure.
Parameters
Measurand Value Type Method Mass Remarks
power 10 W peak value - - 1-10 W/pulse

Exposure 6

Main characteristics
Frequency
Type
Exposure duration continuous for 1 h
Additional info spin echo MRI examination
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 2.35 T - - - -

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

The conclusion is that radiofrequency radiation has a increasing effect on the permeability of the blood-brain barrier. The effect was found for CW radiation and more pronounced for pulsed RF radiation. The effect of MRI high field exposure could not be confirmed.

Study character:

Study funded by

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