Study type: Medical/biological study (experimental study)

Effects of high frequency electromagnetic fields on micronucleus formation in CHO-K1 cells med./bio.

By: Koyama S, Nakahara T, Wake K, Taki M, Isozumi Y, Miyakoshi J
Published in: Mutat Res Genet Toxicol Environ Mutagen 2003; 541 (1-2): 81-89
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Aim of study (acc. to author)

To investigate whether exposure to high frequency electromagnetic fields at a wide range of average SARs from 13 to 100 W/kg with input powers of 7.8 and 13 W could lead to increased micronucleus formation.

Background/further details

Micronucleus formation induced by a high frequency electromagnetic field alone, with bleomycin alone (since bleomycin is known to be a clastogen), or a combination of both was examined. To take the increased temperature into account, the frequency of micronucleus induced was compared to that in cells incubated at 39°C.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 2.45 GHz
Modulation type: CW
Exposure duration: continuous for 18 h
Exposure 2: 2.45 GHz
Modulation type: CW
Exposure duration: continuous for 18 h

Exposure 1

Main characteristics
Frequency 2.45 GHz
Type
Charakteristic
  • guided field
Exposure duration continuous for 18 h
Modulation
Modulation type CW
Exposure setup
Exposure source
Chamber The incubator-like atmosphere inside the cavity with 95% air and 5% CO2 was maintained at 37°C.
Setup Cell suspensions of 3.0, 12.8, and 27.4 ml volume were plated, incubated, and exposed in the three radial compartments (inner, middle, and outer ring) of an annular culture plate.
Sham exposure A sham exposure was conducted.
Additional info As a high temperature control, cells were incubated at 39°C for 18 h.
Parameters
Measurand Value Type Method Mass Remarks
power 7.8 W - measured - input power
SAR 50 W/kg mean estimated - in the middle ring
SAR 39 W/kg mean estimated - in the outer ring
SAR 13 W/kg mean estimated - in the inner ring
Measurement and calculation details

A power meter was used to monitor the input and reflected powers. The SAR in the annular culture plate was estimated by thermography [Guy, 1987]. Estimated average SAR and measured temperature rises are summarized in [Tian et al., 2002].

Exposure 2

Main characteristics
Frequency 2.45 GHz
Type
Charakteristic
  • guided field
Exposure duration continuous for 18 h
Modulation
Modulation type CW
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Additional info Cells were also treated with bleomycin alone (positive control) or followed by RF exposure at an input power of 13 W.
Parameters
Measurand Value Type Method Mass Remarks
power 13 W - measured - input power
SAR 100 W/kg mean estimated - in the middle ring
SAR 78 W/kg mean estimated - in the outer ring
SAR 25 W/kg mean estimated - in the inner ring

Reference articles

  • Tian F et al. (2002): Exposure to 2.45 GHz electromagnetic fields induces hsp70 at a high SAR of more than 20 W/kg but not at 5W/kg in human glioma MO54 cells
  • Guy AW (1987): Dosimetry associated with exposure to non-ionizing radiation: very low frequency to microwaves

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

The micronucleus frequency of cells exposed to a high frequency electromagnetic field at a SAR of up to 50 W/kg was not different to that in sham-expsoed cells. There were statistically significant increases in the micronucleus frequencies of cells in the middle and outer wells of the annular culture plate caused by exposure to a high frequency electromagnetic field at 100 and 78 W/kg, respectively. Although there was an increase of micronucleus formation at 39°C compared with a sham-exposed culture, the rate was lower than after exposure to high frequency electromagnetic field. Furthermore, radiofrequency electromagnetic exposure enhances the frequency of micronuclei after bleomycin-tretament.

Study character:

Study funded by

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