ELF electromagnetic fields increase hydrogen peroxide (H2O2)-induced mutations in pTN89 plasmids

We have examined the mutational effects of hydrogen peroxide (H2O2) in the presence and absence of an extremely low-frequency magnetic field (ELFMF), using pTN89 plasmids. Mutations were detected in the supF gene carried by these plasmids in Escherichia coli. The plasmids were either treated with H2O2 (1 muM) alone at 37 degreesC for 4 h, or were exposed to an ELFMF (60 Hz, 5 millitesla (mT)) simultaneously with H2O2 treatment. The mutation frequency was 2.28 x 10(-4) for H2O2 treatment alone, and 5.81 X 10(-4) for ELFMF exposure with H2O2 treatment. We did not observe any mutations using treatment with ELFMF exposure alone. This indicates that the ELFMF may potentiate H2O2-induced mutation. Sequence analysis of the supF mutant plasmids revealed that base substitutions, G:C --> A:T transitions and G:C --> T:A transversions were dominant in both treatment groups, and there was no difference in the mutation spectrum or the hotspots between the groups. Therefore, ELFMFs may interact and potentiate the damage induced by H2O2, resulting in an increase in the number of mutations.(C) 2004 Elsevier B.V. All rights reserved.