The aim of the study was to replicate previous studies by Ivancsits et al. (Ivancsits et al. 2002, Ivancsits et al. 2003), implicating an increase of DNA strand breaks in primary human fibroblasts intermittently exposed to 50 Hz extremely low frequency electromagnetic fields (ELF-EMF). The aim of the present work was to test the reproducibility of these observations and to explore the origin and nature of the ELF-EMF induced DNA effects (identical experimental conditions and procedures were applied).
Hydrogen peroxide treatment was used to study oxidative stress induced DNA damage.
Exposure | Parameters |
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Exposure 1:
50 Hz
Exposure duration:
5 min on - 10 min off - for 15 hr
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Exposure 2:
50 Hz
Exposure duration:
continuous for 15 hr
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Exposure source |
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Setup | four-coil system consisting of bifilar coils placed in a µ-metal box inside an incubator |
Sham exposure | A sham exposure was conducted. |
Measurand | Value | Type | Method | Mass | Remarks |
---|---|---|---|---|---|
magnetic flux density | 1 mT | - | - | - | - |
electric field strength | 33.2 mV/m | maximum | measured | - | induced field at the edge of a 10 cm petri dish |
electric field strength | 0 mV/m | - | measured | - | in the center of the petri dish |
Exposure source |
|
---|---|
Sham exposure | A sham exposure was conducted. |
Measurand | Value | Type | Method | Mass | Remarks |
---|---|---|---|---|---|
magnetic flux density | 1 mT | - | - | - | - |
electric field strength | 33.2 mV/m | maximum | measured | - | induced field at the edge of a 10 cm petri dish |
electric field strength | 0 mV/m | - | measured | - | in the center of the petri dish |
The data confirmed that intermittent (but not continuous) exposure of human primary fibroblasts to a 50 Hz electromagnetic field (at a magnetic flux density of 1 mT) induces a slight but significant increase of DNA fragmentation in the Comet assay. The authors provide first evidence for this to be caused by the magnetic field rather than the electric field (for this purpose cells of the central and peripheral areas of the Petri dishes were compared). Moreover, the authors showed that electromagnetic field-induced responses in the Comet assay were dependent on cell proliferation, suggesting that processes of DNA replication rather than the DNA itself may be affected. Consistently, the effects in the Comet assay correlated with a reduction of actively replicating cells and a concomitant increase of apoptotic cells in exposed cell cultures, whereas a combined Fpg-Comet assay failed to produce evidence for a notable contribution of oxidative DNA base damage.
Hence, ELF-EMF induced effects in the Comet assay are reproducible under specific conditions and can be explained by minor disturbances in S phase processes and occasional triggering of apoptosis rather than by the generation of DNA damage. Finally, this S phase dependency may explain issues of reproducibility of the ELF-EMF induced Comet assay effects (the fraction of S phase cells in a population is determined by the culture conditions and the cell lines used, and these parameters may vary between laboratories).
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