Time-varying magnetic fields of 60 Hz at 7 mT induce DNA double-strand breaks and activate DNA damage checkpoints without apoptosis.
Published in: Bioelectromagnetics 2012; 33 (5): 383-393
Aim of study (acc. to author)
continuous for 30 min
coils with a diameter of 0.9 cm and 3500 turns of wire wound on an acrylic cylinder; cell culture dish with a diameter of 3.5 or 6 cm placed so at the coil's base that the coil was in the center of the dish
continuous for 0 - 120 min
Main outcome of study (acc. to author)
exposure of human fibroblast and cervical cancer cells to a 60 Hz magnetic field at 7 mT for 0-120 minutes, no significant change in cell viability was observed. Cell viability of the two cell lines was also not altered by magnetic fields of 0-14 mT at an exposure time of 30 minutes. However, DNA double-strand breaks were detected in both cell lines exposed to 7 mT or at higher intensities for 30 or 60 minutes (as shown by formation of gamma-H2AX foci and/or gamma-H2AX expression and comet assay). The DNA damage checkpoint pathway was activated in these cells (as shown by protein expression of phospho-ATM and p-Chk2) without programmed cell death ( apoptosis; as shown by no change in expression of caspase-3, cleaved caspase-3 and PARP). The exposure of the cell lines to a 60 Hz magnetic field did not induce intracellular reactive oxygen species production, suggesting that the observed DNA double-strand breaks were not directly caused by reactive oxygen species. The DNA double-strand breaks mainly occurred at the central region of the culture plates, where the magnetic field was strongest, after a 30 minutes exposure. After 90 minutes, however, the amount of double-strand breaks increased rapidly in the outer regions, where the eddy current and Lorentz force were strong. In conclusion, the data suggest that exposure to a 60 Hz magnetic field of 2-14 mT has a genotoxic potential in both human non- cancerous and cancerous cells even after short exposures of tens of minutes.
Study funded by
Korea Research Foundation (KRF), Korea
Ministry of Knowledge Economy (MKE), Korea
Korea Research Institute of Chemical Technology (KRICT)
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