Yao K, Wu W, Wang K, Ni S, Ye P, Yu Y, Ye J, Sun L. (2008). Electromagnetic noise inhibits radiofrequency radiation-induced DNA damage and reactive oxygen species increase in human lens epithelial cells. Mol Vis 14:964-9.
Cataract is one of the major causes of blindness throughout the world. Both oxidative stress and DNA damage of lens epithelial cells can result in lens opacification. In their previous study, the authors detected significant DNA damage and increase in reactive oxygen species (ROS) in human lens epithelial cells (HLECs) after long-term (24 hours) intermittent exposure to 1800 MHz radiofrequency (RF) field of the Global System for Mobile Communications (GSM). The authors also showed that these effects could be blocked by superposing a “noise” magnetic field.
The aim of the present study was to investigate whether acute exposure (2 hours) to GSM 1800 MHz RF field could induce similar effects (to the authors’ previous study) on cultured HLECs and whether superposing of electromagnetic noise could block or attenuate these potential effects.
The cells were divided into four groups: sham-exposure group; RF radiation group at specific absorption rates (SAR) of 1, 2, 3, or 4 W/kg; noise magnetic field group at 2 mT, and RF radiation group/noise magnetic field. After 2 hours of intermittent exposure (5 min fields on/10 min fields off), or sham-exposure, the ROS level and DNA damage were assessed.
Intracellular reactive oxygen species (ROS) were significantly (P<0.05) increased after 2 hours of exposure to the 1800 MHz RF field at SAR of 2, 3 and 4 W/kg. These effects were significantly suppressed when superposed with electromagnetic noise. No significant elevation of ROS level was detected in the 1 W/kg group. Electromagnetic noise alone had no significant effect on intracellular ROS level compared to sham-exposure.
DNA damage (mostly single strand breaks) was significantly higher at SAR of 3 and 4 W/kg compared to sham-exposure, but no significant increase was observed after exposure at lower SARs. Electromagnetic noise alone did not increase DNA damage in HLEC, and, when superposed on the RF field, it blocked the RF induced DNA damage. There were no significant differences between the RF exposed groups at any SAR and the sham-exposed group in DNA double strand breaks.
Significant increase in DNA single strand breaks observed in this study is consistent with the effect of long term exposure (24 hours) reported previously by the authors. In contrast to the present study, the long-term RF exposure at SAR of 4 W/kg induced significant double strand breaks in the same cells in the authors’ previous study but not the acute exposure in this study. Therefore, it has been suggested the effects of RF exposure are associated with exposure duration.
It has been suggested that coherence was an essential characteristic for electromagnetic fields (EMF) to cause biological effects, and, when an incoherent random electromagnetic noise is superimposed on a coherent EMF signal, observed EMF-induced biological effects would be suppressed.
DNA damage induced by 1800 MHz RF exposure for 2 hours was mainly single strand breaks, and it could be associated with increased ROS production. Electromagnetic noise could block RF-induced ROS formation and DNA damage. Further investigation on the temporal and special coherency hypothesis is required on different cell types and different doses as well as on modulations of RF EMFs.