Effects of 2.45-GHz Electromagnetic Fields with a Wide Range of SARs on Micronucleus Formation in CHO-K1 Cells

Abstract

There has been considerable discussion about the influence of high-frequency electromagnetic fields (HFEMF) on the human body. In particular, HFEMF used for mobile phones may be of great concern for human health. In order to investigate the properties of HFEMF, we have examined the effects of 2.45-GHz EMF on micronucleus (MN) formation in Chinese hamster ovary (CHO)-K1 cells. MN formation is induced by chromosomal breakage or inhibition of spindles during cell division and leads to cell damage. We also examined the influence of heat on MN formation, since HFEMF exposure causes a rise in temperature.CHO-K1 cells were exposed to HFEMF for 2 h at average specific absorption rates (SARs) of 5, 10, 20, 50, 100, and 200 W/kg, and the effects on these cells were compared with those in sham-exposed control cells. The cells were also treated with bleomycin alone as a positive control or with combined treatment of HFEMF exposure and bleomycin. Heat treatment was performed at temperatures of 37, 38, 39, 40, 41, and 42°C.The MN frequency in cells exposed to HFEMF at a SAR of lower than 50 W/kg did not differ from the sham-exposed controls, while those at SARs of 100 and 200 W/kg were significantly higher when compared with the sham-exposed controls. There was no apparent combined effect of HFEMF exposure and bleomycin treatment. On heat treatment at temperatures from 38-42°C, the MN frequency increased in a temperaturedependent manner. We also showed that an increase in SAR causes a rise in temperature and this may be connected to the increase in MN formation generated by exposure to HFEMF.

Effects of a 2450 MHz high-frequency electromagnetic field with a wide range of SARs on the induction of heat-shock proteins in A172 cells

“…A culture dish is placed on two slits, which were bored into the wider wall of the waveguide. Cells in the culture dish are exposed to the HFEMF through these slits [Koyama et al, 2004]. The two slits are pinching shaped, which enhances the coupling of the electromagnetic field to increase the effective exposure area.…”

“…This HFEMF exposure facility and its application for the batch irradiation of monolayer cells attached to the bottom of tissue culture dishes have been described previously in detail [Koyama et al, 2004]. Briefly, the applicator is based on a rectangular waveguide, with the size of the waveguide determined to be 110 mm (width) Â 55 mm (height) Â 310 mm (depth).…”

“…The exposure is made in the second compartment from the termination of the waveguide, where the coupling with field is strongest [Koyama et al, 2004]. The SAR value is labeled by the local SAR at the center of this compartment.…”

Cellular Biology Aspects of Mobile Phone Radiation

“…Micronucleus (MN) is frequently used as an index for genotoxicity evaluation of cells as well as the above comet assay. MN is a phenomenon that DNA in a cell was damaged and a part of DNA was isolated from the original nucleus as a small nucleus (Koyama et al, 2003(Koyama et al, , 2004 . The following is a brief explanation for analysis method of MN formation:…”

“…MN formation occurs extremely infrequently and spontaneously. Therefore, MN formation is evaluated both in untreated and treated groups with appropriate statistical method (Koyama et al, 2003(Koyama et al, , 2004 .…”