Effect of exposure to 900 MHz radiofrequency radiation on intrachromosomalrecombination in pKZ1 mice

Radiofrequency (RF) radiation emitted from mobile phones is not considered to be directly genotoxic, but it may have downstream effects on cellular DN A. We studied the effect of 4 W/kg pulsed 900 MHz RIF radiation on somatic intrachromosomal recombination in the spleen in the pKZ1 recombination muta genesis model. Somatic intrachromosomal recombination inversion events were detected in spleen tissue of pKZ1 mice by histochemical staining for E. co li beta -galactosidase protein in cells in which the lacZ transgene has und ergone an inversion event. pKZ1 mice were exposed daily for 30 min to plane -wave fields of 900 MHz with a pulse repetition frequency of 217 Hz and a p ulse width of 0.6 ms for 1, 5 or 25 days. Three days after the last exposur e, spleen sections were screened for DNA inversion events. There was no sig nificant difference between the control and treated groups in the 1- and 5- day exposure groups, but there was a significant reduction in inversions be low the spontaneous frequency in the 25-day exposure group. This observatio n suggests that exposure to RIF radiation can lead to a perturbation in rec ombination frequency which may have implications for recombination repair o f DNA. The biological significance of a reduction below the spontaneous fre quency is not known. The number of mice in each treatment group in this stu dy was small (n = 10 or n = 20). Therefore, repetition of this study with a larger number of animals is required to confirm these observations. (C) 20 01 by Radiation Research Society.