Study type: Medical/biological study (experimental study)

Adaptive response in mice exposed to 900 MHz radiofrequency fields: Bleomycin-induced DNA and oxidative damage/repair. med./bio.

Published in: Int J Radiat Biol 2015; 91 (3): 270-276

Aim of study (acc. to author)

It should be investigated if exposure of mice to a 900 MHz electromagnetic field induces an adaptive response with higher resistance against bleomycin.

Background/further details

Bleomycin causes damages in cells and tissue comparable to the damage caused by ionizing radiation.
The experiment was divided into two parts: In the first part, DNA damage was examined and in the second part, oxidative stress and the antioxidative status were examined. For the first part, 24 mice and for the second part, 48 mice were divided into 6 groups, respectively (each n=4 and n=8, respectively): 1) cage control, 2) sham exposure, 3) exposure to electromagnetic field only, 4) injection of bleomycin only, 5) sham exposure + bleomycin, 6) exposure + bleomycin. The experiment of the first part was conducted twice.
Bleomycin was administered 4 hours after the last exposure.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 900 MHz
Modulation type: CW
Exposure duration: continuous for 4 h/day for 7 days

Exposure 1

Main characteristics
Frequency 900 MHz
Type
Exposure duration continuous for 4 h/day for 7 days
Modulation
Modulation type CW
Exposure setup
Exposure source
Chamber small plastic boxes
Setup single restrained mice were kept in small plastic boxes and exposed in an in-house built GTEM cell; the location and orientation of the animals in the GTEM cell during exposure was monitored
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
power density 120 µW/cm² - measured - -
SAR 50 mW/kg - calculated - estimation

Reference articles

  • Cao Y et al. (2011): Induction of adaptive response: pre-exposure of mice to 900 MHz radiofrequency fields reduces hematopoietic damage caused by subsequent exposure to ionising radiation.
  • Cao Y et al. (2010): Effects of 900-MHz Microwave Radiation on gamma-Ray-Induced Damage to Mouse Hematopoietic System.
  • McIntosh RL et al. (2010): A Comprehensive Tissue Properties Database Provided for the Thermal Assessment of a Human at Rest.
  • Gabriel C (1996): Compilation of the dielectric properties of body tissues at RF and microwave frequencies.

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

No significant differences could be observed between cage control, sham exposure and exposure to the electromagnetic field alone (groups 1-3) in all experiments.
In mice of groups with bleomycin injection (4-6), a significant increase of DNA damage could be observed 20 minutes after the injection compared to groups 1-3. In consecutive measurements, a progressional decrease of DNA damage with increasing time was observed in groups 4-6, with significant lower DNA damage in the group with exposure to the electromagnetic field (group 6) compared to groups without exposure (groups 4 and 5).
Groups 4-6 showed significantly increased levels of malondialdehyde and significantly decreased levels of superoxide dismutase in all tissues compared to groups 1-3. Additionally, the level of malondialdehyde was significantly lower in plasma and liver and the level of superoxide dismutase significantly higher in the lung in group 6 compared to groups 4 and 5.
The authors conclude that exposure of mice to a 900 MHz electromagnetic field induces an adaptive response with higher resistance against genotoxic or oxidative effects of bleomycin and that this study provides some evidence on the mechanisms of action underlying such an adaption.

Study character:

Study funded by

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