Study type: Medical/biological study (experimental study)

Non-thermal exposure to radiofrequency energy from digital wireless phones does not affect ornithine decarboxylase activity in L929 cells med./bio.

By: Desta AB, Owen RD, Cress LW
Published in: Radiat Res 2003; 160 (4): 488-491
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Aim of study (acc. to author)

Murine cells were exposed to radiofrequency irradiation from a time division multiple access (TDMA) mobile phone operating at 835 MHz frequency to determine the effect of irradiation on ornithine decarboxylase (ODC) activity in cultured cells.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 835 MHz
Modulation type: pulsed
Exposure duration: continuous for 8 h
  • power: 3 mW maximum (0.25; 0.50; 0.75; 1.0; 1.5; 2.0; 2.5; 3.0 mW)
  • SAR: 1 W/kg maximum (non-thermal)
  • SAR: 5 W/kg maximum (1-5 W/kg)
  • SAR: 10 W/kg maximum (6-10 W/kg)
  • SAR: 15 W/kg maximum (11-15 W/kg)

Exposure 1

Main characteristics
Frequency 835 MHz
Type
Charakteristic
  • guided field
Exposure duration continuous for 8 h
Modulation
Modulation type pulsed
Pulse width 6.7 ms
Additional info

TDMA
Exposure setup
Exposure source
Chamber The Crawford cell and a sham-exposure chamber with similar dimensions were placed in the same water-jacketed incubator maintained at 37°C.
Setup Four 25-cm² flasks were placed in each exposure chamber with two flasks on each shelf. Effects of different temperatures in the absence of an RF field were examined in two satellite chambers (Plexiglas boxes receiving a controlled air flow from the central incubator).
Additional info Though the exposure system produced a non-uniform spatial distribution of the absorbed power it was not replaced by a better one because the aim of the study was to reproduce the results obtained in the reference article. In addition, the longer exposure time chosen was expected to result in a more homogeneous temperature distribution.
Parameters
Measurand Value Type Method Mass Remarks
power 3 mW maximum measured - 0.25; 0.50; 0.75; 1.0; 1.5; 2.0; 2.5; 3.0 mW
SAR 1 W/kg maximum measured - non-thermal
SAR 5 W/kg maximum measured - 1-5 W/kg
SAR 10 W/kg maximum measured - 6-10 W/kg
SAR 15 W/kg maximum measured - 11-15 W/kg
Measurement and calculation details

Forward and reflected powers were monitored using power meters, transmitted power was not measured. The temperature of one flask in each chamber was monitored continuously using a non-perturbing probe. The SAR was calculated from the plots of temperature over time.

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

No statistically significant difference in ornithine decarboxylase activity was found between exposed and sham-exposed cells at non-thermal specific absorption rates (SARs). At SARs which resulted in measurable heating of the medium, a dose-dependent decrease in enzymatic activity was observed. It was shown to be consistent with a comparable decrease caused by non-radiofrequency irradiation heating. Thus the authors observed only the well-known enzyme inhibition due to heating, rather than the previously reported enhancement attributed to radiofrequency exposure (e.g. publication 3382 and publication 9896).

Study character:

Study funded by

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