Study type: Medical/biological study (experimental study)

Effect of exposure to 900 MHz radiofrequency radiation on intrachromosomal recombination in pKZ1 mice med./bio.

By: Sykes PJ, McCallum BD, Bangay MJ, Hooker AM, Morley AA
Published in: Radiat Res 2001; 156 (5) Pt 1: 495-502
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Aim of study (acc. to author)

The pKZ1 recombination mutagenesis model was used to determine if exposure to radiofrequency radiation (whole-body SAR 4 W/kg) would induce somatic intrachromosomal recombination in spleen tissue. The pKZ1 recombination mutagenesis model enabels detection of somatic intrachromosomal recombination inversion events in response to DNA-damaging agents.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 900 MHz
Modulation type: pulsed
Exposure duration: repeated daily exposure for 30 min/day for 1, 5 or 25 days (5 days/week)
  • SAR: 4 W/kg average over mass (whole body)

Exposure 1

Main characteristics
Frequency 900 MHz
Type
Charakteristic
  • guided field
Exposure duration repeated daily exposure for 30 min/day for 1, 5 or 25 days (5 days/week)
Additional info plane-wave fields
Modulation
Modulation type pulsed
Pulse width 0.6 ms
Repetition frequency 217 Hz
Exposure setup
Exposure source
Chamber The waveguide made of aluminium was a WG3 with a rectangular cross section with external dimensions of 296 mm x 150 mm and a length of 1700 mm. Coaxial to waveguide E-field exciter antennae were built into each end. The RF radiation received by the antenna at the other end of the waveguide was dissipated in a resistive high-power coaxial attenuator. Two tuning screws allowed to minimize the amount of reflected energy.
Setup The waveguide had 13 access ports aligned along its length and contained a solid block of Styrofoam that had 13 shaped polycarbonate tubes glued into it. The tubes had bayonet connectors that received and locked the mouse holders into position. The mouse holder tubes (length 173 mm; diameter 32 mm inside, 36 mm outside) made of polycarbonate enabled restraint of a 30-g mouse. The capsules were fully contained except for the hole in the capsule near the nose of the mouse for letting in the air.
Additional info The mice in the multiple-exposure experiments were placed randomly in the waveguide to average out any variations in SAR along the waveguide. Matched sham-exposed mice were placed in the exposure apparatus with the air flow on but no RF radiation for the same period as the treated mice.
Parameters
Measurand Value Type Method Mass Remarks
SAR 4 W/kg average over mass measured and calculated whole body -
Measurement and calculation details

Measurements of transmitted, received and reflected powers were made using an RF power meter with a power sensor and associated attenuator connected to a directional coupler. Less than 2% of the transmitted energy was lost in the waveguide when there were no animals present, and negligible (40 dBµV/m) RF-radiation energy leaked from the apparatus. A detection diode connected to an oscilloscope enabled the monitoring of the pulse waveform. Two methods were used to determine the SAR received by the animals: The first method used a power-loss equation. Power measurements were performed on the waveguide, with and without up to ten animals or phantoms present. The second method was to measure the temperature increase in mouse phantoms filled with semi-liquid material that had dielectric properties similar to muscle tissue. Both measurement methods gave very similar results, with average calculated SARs of 4 W/kg and 3.3 W/kg, respectively.

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

There was no significant difference between the control and treated animals in the 1- and 5-day group. But there was a significant reduction in inversions below the spontaneous frequency in the 25-day group. The results suggest that exposure to radiofrequency radiation can lead to a perturbation in recombination frequency which may have implications for recombination repair of DNA.

Study character:

Study funded by