Medical/biological study (experimental study)

Effects on micronuclei formation of 60-Hz electromagnetic field exposure with ionizing radiation, hydrogen peroxide, or c-Myc overexpression med./bio.

By: Jin YB, Kang GY, Lee JS, Choi JI, Lee JW, Hong SC, Myung SH, Lee YS

Published in: Int J Radiat Biol 2012; 88 (4): 374-380

Aim of study (acc. to author)

To study the combined effects of exposure to an extremely low frequency magnetic field and various stress factors including ionizing radiation, hydrogen peroxide, and oncogenic c-Myc activation on micronucleus formation in non-tumorigenic NIH3T3 cells and in human lung fibroblasts.

Background/further details

For the positive control, cells were exposed to various doses of gamma radiation (0-4 Gy) at a dose rate of 3.81 Gy/min. For H₂O₂ exposure, cells were treated with H₂O₂ (0-200 mM) for 4 h.
For the co-exposure experiments, there were three conditions: 1) cells exposed to an extremely low frequency magnetic field for 4 h, 2) cells exposed to an extremely low frequency magnetic field for 4 h immediately after irradiation with gamma rays (2 Gy), and 3) cells exposed to an extremely low frequency magnetic field for 4 h in the presence of H₂O₂ (100 µM).

Endpoint

genotoxicity/mutation: micronucleus formation

Exposure

- 60 Hz
- 50/60 Hz
- magnetic field
- low frequency
- co-exposure

Exposure	Parameters
Exposure 1: 60 Hz Exposure duration: continuous for 4 h	magnetic flux density: 0.01 mT magnetic flux density: 0.5 mT magnetic flux density: 1 mT

General information

Cells were exposed in the following eight groups: i) exposure to H₂O₂ ii) gamma radiation iii) exposure to ELF iv) sham exposure v) ELF exposure + exposure to H₂O₂ (100µM) vi) ELF exposure + gamma radiation (2 Gy) vii) c-Myc activation viii) ELF exposure + c-Myc activation

Exposure 1

Main characteristics

Frequency	60 Hz
Type	magnetic field
Exposure duration	continuous for 4 h

Exposure setup

Exposure source	Merritt coils
Setup	Merritt-coil system consisting of four square coils with 26 turns of wire in the outer and 11 turns in the inner coils, connected in series; cage with three testing floors (top, middle, bottom); exposure system shielded with ferrite material and placed inside a water-cooled incubator at a constant temperature of 37°C; cells placed in 60 mm Petri dishes inside the exposure system
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	0.01 mT	-	measured	-	-
magnetic flux density	0.5 mT	-	measured	-	-
magnetic flux density	1 mT	-	measured	-	-

Additional parameter details

geomagnetic field: 0.04 mT ambient 60 Hz field: 0.1 µT

Exposed system:

intact cell/cell culture
NIH3T3 cells (mouse fibroblasts) and WI38 cells (human lung fibroblasts), normal and transfected with a c-Myc-containing vector or with an empty vetor

Methods Endpoint/measurement parameters/methodology

genotoxicity/mutation: micronucleus formation (Giemsa staining)

Investigated system:

DNA/RNA

Time of investigation:

after exposure

Main outcome of study (acc. to author)

The data did not show any significant differences between the cells exposed to extremely low frequency magnetic fields alone and the unexposed cells. Moreover, no synergistic effects were observed when extremely low frequency magnetic fields exposure was combined with ionizing radiation, hydrogen peroxide, and oncogenic c-Myc activation.
In conclusion, the findings demonstrate that extremely low frequency magnetic fields did not enhance micronucleus frequency caused by ionizing radiation, hydrogen peroxide, and oncogenic c-Myc activation.

Study character:

medical/biological study
experimental study
full/main study

Study funded by

Ewha Womans University, Seoul, Korea
Korea Institute of Energy Technology and Planning (KETEP), Korea
Ministry of Knowledge Economy (MKE), Korea

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