Combined effects of extremely low frequency electromagnetic fields (ELFMFs) and X-rays or H/sub 2/O/sub 2/ on mutation in pTN89 plasmids

We detected mutations that occurred in the supF gene carried by pTN89 plasmids in Escherichia coli (E. coli) to examine the effects of extremely low frequency electromagnetic fields (ELFMF) and X-rays or H/sub 2/O/sub 2/ on the plasmids. This E. coli system was developed by Obata et al. (1998) and can detect a mutation at the single base level in the supF gene. In experiments, the plasmids were subjected to sham exposure or exposed to an ELFMF (60 Hz, 5 mT (millitesla)), with or without X-ray irradiation (10 Gy). For the combined treatments, exposure to the ELFMF was done immediately before or after X-ray irradiation. Increased mutation frequency was not detected following exposure to a magnetic field alone, or after sham exposure. The mutation frequency for X-rays followed by an ELFMF was statistically significant compared to the other treatments.