Abstract
Recently, it becomes practical that people are exposed to strong static magnetic fields (SMFs) up to several Tesla such as MRI. However, experimental evidences related to evaluation of biological effects of strong SMFs are not enough for health risk evaluation to date. Among the studies regarding biological effects of SMFs exposure, several reports suggested that exposure to SMFs have very weak mutagenicity by enhancement of oxidative stress or effects on life time of reactive oxygen species that is induced spontaneously or chemically within cells. In this study, we focused on effects of SMFs exposure on superoxide and the effects were investigated by evaluation of mutagenicity and co-mutagenicity of SMFs in SOD-deficient E. coli.
Superconducting magnet JMTD-10C13E-NC (JASTEC), which generates up to 13 T static vertical magnetic field, was used for SMFs exposure. Temperature in the bore was kept to be 37 deg C. In this study, E. coli QC774 (sodA sodB, Cmr Kmr) and its parental strain GC4468 were used. These strains were exposed to 5, 10 or 13 T SMFs for 24 hr at 37 deg C in LB medium with or without 25 μM plumbagin. After the exposure, survival rate and mutation frequency from Thy+ to Thy- was determined.
In the result, for both mutagenicity and co-mutagenicity, no statistically significant difference in Thy- mutant frequency was observed between SMF-exposed cells and unexposed cells in all of magnetic flux densities for both E. coli QC774 and GC4468. It suggests that SMF up to 13T does not have mutagenicity nor affect mutagenicity of superoxide in SOD-deficient E. coli QC774.
