Intracellular DNA Damage Induced by Non-thermal, Intense Narrowband Electric Fields

Intracellular DNA damages caused by intense burst sinusoidal electric fields (IBSEFs) were investigated by means of an alkaline comet assay method. Non-thermal, 200 mu s-long IBSEF with various frequency values (300 kHz-100MHz) and strengths (up to 200 kV/m) was applied to Chinese hamster ovary (CHO) cells in a suspending medium between I mm gap parallel electrodes. The comet assay suggests that 100 kV/m IBSEF with frequencies exceeding I MHz or 100 MHz IBSEFs with field strengths exceeding 3 kV/m induces significant DNA damage. According to the numerical calculation of the electric field over a simplified cell model under an alternating electric field, the intracellular field strength increases with increasing alternating frequency. The minimum level of the field strength that induces the DNA damage is in the range of 10-30 kV/m. This intracellular strong field might trigger biological processes leading to the DNA damage.