Influence of high-frequency electromagnetic fields on different modes of cell death and gene expression.
OBJECTIVE
International thresholds for exposure to non-ionizing radiation leading to non-thermal effects were conservatively set by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). The aim of this study was to examine whether biological effects such as different modes of cell death and gene expression modifications related to tumorgenesis are detectable above the threshold defined.


METHODS
Human leukaemia cells (HL-60) grown in vitro were exposed to electromagnetic fields (EMF; t 1/2(r) about 1 ns; field strength about 25 times higher than the ICNIRP reference levels for occupational exposure) leading to non-thermal effects using a high-voltage-improved GTEM cell 5302 (EMCO) connected to a pulse generator NP20 (C = 1 nF, U(Load) = 20kV). HL-60 cells were harvested at 0, 24, 48 and 72 h after radiation exposure. Micronuclei, apoptosis and abnormal cells (e.g. necrosis) were determined using morphological criteria. In parallel, the expression of 1176 genes was measured using Atlas Human 1.2. Array. Based on high data reproducibility calculated from two independent experiments (> 99%), array analysis was performed.


RESULTS
No significant change in apoptosis, micronucleation, abnormal cells and differential gene expression was found.


CONCLUSIONS
Exposure of HL-60 cells to EMFs 25 times higher than the ICNIRP reference levels for occupational exposure failed to induce any changes in apoptosis, micronucleation, abnormal morphologies and gene expression. Further experiments using EMFs above the conservatively defined reference level set by the ICNIRP may be desirable.
Port
M
M
Institute of Radiobiology, German Armed Forces, Neuherbergstr. 11, D-80937 Munich, Germany. matthias.port@web.de
Abend
M
M
Römer
B
B
Van Beuningen
D
D
D017209:Apoptosis / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D004574:Electromagnetic Fields / Q000009:adverse effects*; D015972:Gene Expression Regulation, Neoplastic / Q000528:radiation effects*; D018922:HL-60 Cells; D006801:Humans; D008452:Maximum Allowable Concentration; D015162:Micronucleus Tests; D009336:Necrosis; D016273:Occupational Exposure / Q000009:adverse effects / Q000592:standards; D011829:Radiation Dosage; D011846:Radio Waves / Q000009:adverse effects*