Medical/biological study (experimental study)

Absence of DNA damage after 60-Hz electromagnetic field exposure combined with ionizing radiation, hydrogen peroxide, or c-Myc overexpression med./bio.

By: Jin YB, Choi SH, Lee JS, Kim JK, Lee JW, Hong SC, Myung SH, Lee YS

Published in: Radiat Environ Biophys 2014; 53 (1): 93-101

Aim of study (acc. to author)

To investigate whether exposure to a 60 Hz-magnetic field alone or in combination with ionizing radiation, hydrogen peroxide or c-Myc overexpression induces a DNA damage in different cell lines.

Background/further details

In a previous study, the authors showed that magnetic field exposure alone or in combination with ionizing radiation, hydrogen peroxide or c-Myc overexpression did not increase the number of micronuclei and therefore did not induce a chromosomal damage (Jin et al. 2012 ). To test whether these treatments induce a primary DNA damage, in this study the comet assay was performed.
Different experiments were performed: 1.) magnetic field exposure or sham exposure, 2.) magnetic field exposure + ionizing radiation (1 Gy), 3.) magnetic field exposure + hydrogen peroxide (50 µM) and 4.) magnetic field exposure + c-Myc overexpression.
For c-Myc overexpression, cells were transfected with a c-Myc-containing vector or with an empty vector.
Exposure to the magnetic field was performed before or after the other treatments.

Endpoint

genotoxicity/mutation: DNA damage

Exposure

Exposure	Parameters
Exposure 1: 60 Hz Exposure duration: continuous for 4 or 16 hours	magnetic flux density: 1 mT (at the center of the incubator)

General information

Different experiments were performed: 1.) magnetic field exposure or sham exposure, 2.) magnetic field exposure + ionizing radiation (1 Gy), 3.) magnetic field exposure + hydrogen peroxide (50 µM) and 4.) magnetic field exposure + c-Myc overexpression.

Exposure 1

Main characteristics

Frequency	60 Hz
Type	magnetic field
Exposure duration	continuous for 4 or 16 hours

Exposure setup

Exposure source	Merritt coils
Setup	a Merrit coil configuration consisting of four square coils (26 turns in the outer coils and 11 turns in the inner coils) was used; conducting wire of the coils had a diameter of 0.0014 mm; incubator consisted of three floors (upper, middle, bottom); temperature was maintained at 37 ± 0.3 °C; cells in 60-mm petri dishes were placed in the center of the floors; spatial variation of the magnetic field was less than 3%; magnetic field shielding system (made from ferrite material) was adopted to block strong magnetic fields from outside
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	1 mT	-	calculated	-	at the center of the incubator

Additional parameter details

geomagnetic field was approximately 0.04 mT, 60 Hz-background magnetic field less than 0.001 mT

Exposed system:

intact cell/cell culture
NIH3T3 cells (mouse fibroblast cell line), WI-38 cells (human lung fibroblast cells), L-132 (human embryonic lung tissue), MCF10A cells (human breast epithelial cells); partially transfected with a c-Myc or empty vector

Methods Endpoint/measurement parameters/methodology

genotoxicity/mutation: DNA damage (comet assay)

Investigated system:

DNA/RNA

Time of investigation:

after exposure

Main outcome of study (acc. to author)

In the first experiment, no significant differences were observed between exposed and sham exposed cell cultures. Moreover, no synergistic effects were observed when magnetic field exposure was combined with ionizing radiation, hydrogen peroxide, or overexpression of c-Myc.
The data confirm the results of the previous study: Exposure to a 60 Hz-magnetic field alone and in combination with ionizing radiation, hydrogen peroxide or c-Myc overexpression did not induce a primary DNA damage in different cell lines.

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

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