Medical/biological study (experimental study)

Extremely low frequency (ELF) magnetic fields enhance chemically induced formation of apurinic/apyrimidinic (AP) sites in A172 cells med./bio.

By: Koyama S, Sakurai T, Nakahara T, Miyakoshi J

Published in: Int J Radiat Biol 2008; 84 (1): 53-59

Aim of study (acc. to author)

This in vitro study was conducted to examine the possible genotoxic effects of extremely low frequency magnetic fields in human glioblastoma cells.

Background/further details

Genotoxicity was estimated by the number of apurinic/apyrimidinic sites in the genomic DNA. Apurinic/apyrimidinic sites of the DNA are common DNA lesions. The human glioblastoma cells were exposed to extremely low frequency magnetic fields alone and plus chemical mutagen (methyl methanesulfonate or hydrogen peroxide).
The applied magnetic flux density of 5 mT is ten times higher as the ICNIRP reference level.

Endpoint

genotoxicity/mutation: DNA damage

Exposure

Exposure	Parameters
Exposure 1: 60 Hz Exposure duration: continuous for 2, 4, 8, 16 or 24 h	magnetic flux density: 5 mT effective value

General information

cells were treated in six groups: i) exposure to EMF ii) exposure to methyl methanesulfonate (MMS) iii) exposure to EMF + exposure to MMS iv) exposure to hydrogen peroxide (H₂O₂) v) exposure to EMF + exposure to H₂O₂ vi) sham exposure

Exposure 1

Main characteristics

Frequency	60 Hz
Type	magnetic field
Exposure duration	continuous for 2, 4, 8, 16 or 24 h

Exposure setup

Exposure source	Helmholtz coils
Setup	Helmholtz coil with an inner diameter of 250 mm, 160 mm long, with 128 turns, inside a CO2 incubator; incubator shielded on the inside with silicon steel and on the outside with Permalloy C
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	5 mT	effective value	-	-	-

Reference articles

Miyakoshi J et al. (1996): Exposure to magnetic field (5 mT at 60 Hz) does not affect cell growth and c-myc gene expression
Miyakoshi J et al. (1994): A newly designed experimental system for exposure of mammalian cells to extremely low frequency magnetic fields

Exposed system:

intact cell/cell culture
A172 (human glioblastoma cells)

Methods Endpoint/measurement parameters/methodology

genotoxicity/mutation: DNA damage (number of apurinic/apyrimidinic sites, spectrophotometry)
cell viability/cell division/proliferation: cell survival (trypan blue stain, haemocytometer)

Investigated system:

DNA/RNA

Investigated organ system:

brain/CNS

Time of investigation:

during exposure
after exposure

Main outcome of study (acc. to author)

The cell survival was signigicant different in cells exposed to extremely low frequency magnetic field compared to sham exposed cells from 2 to 24 hours exposure time. Treatment with chemical mutagens resulted in time dependent decrease in cell survival. The co-exposure with extremely low frequency magnetic field did not differ significantly from the cell survival in chemical mutagen alone treated cells.
No significant difference in the number of apurinic/apyrimidinic sites between exposed and sham exposed cells was observed.
The mutagen treatment alone increased the number of apurinic/apyrimidinic sites with longer treatment times. The co-exposure (extremely low frequency magnetic field exposure plus chemical mutagen) increased apurinic/apyrimidinic site levels compared with the chemical mutagens alone.
These data suggest that the number of apurinic/apyrimidinic sites induced by the chemical mutagens methyl methanesulfonate or hydrogen peroxide is enhanced by the exposure to extremely low frequency magnetic fields at 5 mT.

Study character:

medical/biological study
experimental study
full/main study

Study funded by

not stated/no funding

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