Study type: Medical/biological study (experimental study)

The number of genes changing expression after chronic exposure to Code Division Multiple Access or Frequency DMA radiofrequency radiation does not exceed the false-positive rate. med./bio.

Published in: Proteomics 2006; 6 (17): 4739-4744

Aim of study (acc. to author)

To study if exposure to cell phone radiofrequency irradiations induce changes in gene expression.

Background/further details

The experiments were repeated three times each for both CDMA and FDMA exposures.
Cells exposed to 0.68 Gy of X-rays were used as positive controls.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 835.62 MHz
Exposure duration: continuous for 24 h
  • SAR: 5 W/kg average over time (± 2.1 W/kg)
Exposure 2: 847.74 MHz
Modulation type: pulsed
Exposure duration: continuous for 24 h
  • SAR: 5 W/kg average over time (± 2.1 W/kg)

General information

A detailed description of the RTL device and its environmental controls has been given in several publications [Moros et al., 1998 and 1999; Pickard et al., 1999 and 2000].

Exposure 1

Main characteristics
Frequency 835.62 MHz
Type
Charakteristic
  • guided field
Exposure duration continuous for 24 h
Additional info FDMA
Modulation
Modulation type cf. additional info
Additional info

FDMA, dithered ± 0.015 MHz

Exposure setup
Exposure source
Chamber The radial transmission line (RTL) was formed by two horizontal parallel electrically conducting plates. A central conical aluminium antenna emitted TEM waves radially outward that were terminated by an annulus of RF-absorbing foam. The thermally conductive aluminium bottom plate (6 mm thick) minimised temperature gradients among the exposed flasks placed equidistantly around the antenna. The temperature of the culture media during RF and sham exposure was 37 ± 0.3°C [Moros et al., 1999].
Setup Both powered and sham RTLs were loaded with 16 T75 culture flasks containing 40 ml of culture medium, 15 of them being dummy flasks.
Sham exposure A sham exposure was conducted.
Additional info For positive control, cultured cells were first maintained in the incubator for an additional 24 h (to mirror the length of RF exposure), then irradiated with 0.68 Gy of X-rays, and afterwards placed back into the incubator for a 4-h recovery. Another identically treated flask of cells was sham exposed in the X-ray irradiator.
Parameters
Measurand Value Type Method Mass Remarks
SAR 5 W/kg average over time - - ± 2.1 W/kg

Exposure 2

Main characteristics
Frequency 847.74 MHz
Type
Charakteristic
  • guided field
Exposure duration continuous for 24 h
Additional info CDMA
Modulation
Modulation type pulsed
Pulse width 1.25 ms
Duty cycle 40 %
Additional info

CDMA, nominally spread 1.2288 MHz, dropping off rapidly beyond the band edge (-50.5 dBc at ± 900 kHz). Time domain behaviour consisting of 1.25-ms pulses with pseudorandom spacing and an approximate 40% duty cycle.

Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 5 W/kg average over time - - ± 2.1 W/kg

Reference articles

  • Pickard WF et al. (2000): Experimental and numerical determination of SAR distributions within culture flasks in a dielectric loaded radial transmission line.
  • Pickard WF et al. (1999): Simplified model and measurement of specific absorption rate distribution in a culture flask within a transverse electromagnetic mode exposure system.
  • Moros EG et al. (1999): The radial transmission line as a broad-band shielded exposure system for microwave irradiation of large numbers of culture flasks.
  • Moros EG et al. (1998): A compact shielded exposure system for the simultaneous long-term UHF irradiation of forty small mammals: I. Electromagnetic and environmental design.

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

The number of gene expression changes induced by irradiation was not greater than the number of false positives expected based on a sham exposure versus sham exposure comparison.
In contrast, the X-rays radiated samples showed higher number of gene expression changes than in the sham exposure versus sham exposure comparison.

Study character:

Study funded by

Related articles