Study type: Medical/biological study (experimental study)

Multiple power-density windows and their possible origin med./bio.

By: Blackman CF, Kinney LS, House DE, Joines WT
Published in: Bioelectromagnetics 1989; 10 (2): 115-128
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Aim of study (acc. to author)

In some previous in vitro experiments it was found that the calcium efflux in chicken brain tissue could be altered by defined ranges of frequency-, modulation-, and power density -dependent radiofrequency exposure. These are the so called power density windows.
So the purpose of this study was 1) to confirm earlier data indicating that modulated RF fields exhibit multiple power density windows capable to alter calcium efflux of chicken brain tissue, 2) to extend the power density range in search of possible additional power density windows, and 3) and to develop a speculative mechanism of action.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 MHz
Modulation type: AM
Exposure duration: continuous for 20 min
  • power density: 7.5 W/m² minimum (e: 1.75 mW/cm², 2.3 mW/cm², 3.85 mW/cm², 4.5 mW/cm², 5.57 mW/cm², 5.85 mW/cm², 6.82 mW/cm², 7.08 mW/cm², 7.65 mW/cm², 7.77 mW/cm², 8.19 mW/cm², 8.66 mW/cm², 8.82 mW/cm², 10.6 mW/cm² and 14.7 mW/cm²)

Exposure 1

Main characteristics
Frequency 50 MHz
Type
Waveform
Charakteristic
  • guided field
Exposure duration continuous for 20 min
Modulation
Modulation type AM
Modulation frequency 16 Hz
Exposure setup
Exposure source
Setup A tube containing one half of the brain was placed in the chamber and maintained at 37°C
Additional info The tube containing the other half was placed in a water bath at 37°C for 20 min.
Parameters
Measurand Value Type Method Mass Remarks
power density 7.5 W/m² minimum measured - e: 1.75 mW/cm², 2.3 mW/cm², 3.85 mW/cm², 4.5 mW/cm², 5.57 mW/cm², 5.85 mW/cm², 6.82 mW/cm², 7.08 mW/cm², 7.65 mW/cm², 7.77 mW/cm², 8.19 mW/cm², 8.66 mW/cm², 8.82 mW/cm², 10.6 mW/cm² and 14.7 mW/cm²
Additional parameter details

Geomagnetic field was 38 µT, 60°N; SAR_N: 0.36 mW/kg per mW/cm²

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

Earlier findings of two power density windows between 0.37 to 4.50 mW/cm2, leading to an increased calcium efflux, could be reinforced by the data obtained in this study. Furthermore an enhanced calcium efflux at 1.75, 3.85, 5.57, 6.82, 7.65, 7.77, and 8.82 mW/cm2 was observed in this study.
In brief, the speculative mechanism of action is proposed as a field-induced change e.g. at the cell membrane.

Study character:

Study funded by

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