Increase in radiation-induced HPRT gene mutation frequency after nonthermal exposure to nonionizing 60 Hz electromagnetic fields.
It is widely accepted that moderate levels of nonionizing electric or magnetic fields, for example 50/60 Hz magnetic fields of about 1 mT, are not mutagenic. However, it is not known whether such fields can enhance the action of known mutagens. To explore this question, a stringent experimental protocol, which included blinding and systematic negative controls, was implemented, minimizing the possibility of observer bias or experimental artifacts. As a model system, we chose to measure mutation frequencies induced by 2 Gy gamma rays in the redox-sensitive hypoxanthine-guanine phosphoribosyl transferase (HPRT) gene in Chinese hamster ovary cells. We tested whether a 12-h exposure to a 60 Hz sinusoidally oscillating magnetic-flux density (Brms = 0.7 mT) could affect the mutagenic effects of ionizing radiation on the HPRT gene locus. We determined that the magnetic-field exposure induced an approximate 1.8-fold increase in HPRT mutation frequency. Additional experiments at Brms = 0.23 and 0.47 mT revealed that the effect was reduced at lower flux densities. The field exposure did not enhance radiation-induced cytotoxicity or mutation frequencies in cells not exposed to ionizing radiation. These results suggest that moderate-strength, oscillating magnetic fields may act as an enhancer of mutagenesis in mammalian cells.
Walleczek
J
J
Department of Radiation Oncology, Stanford University Medical School, California 94305-5403, USA.
Shiu
E C
EC
Hahn
G M
GM
D000818:Animals; D016466:CHO Cells; D002470:Cell Survival / Q000528:radiation effects; D006224:Cricetinae; D004260:DNA Repair; D004574:Electromagnetic Fields; D007041:Hypoxanthine Phosphoribosyltransferase / Q000235:genetics*; D009154:Mutation; D013696:Temperature; D014732:Vibration
D007041:Hypoxanthine Phosphoribosyltransferase