Exposure of mammalian cells to 60‐Hz magnetic or electric fields: Analysis of DNA repair of induced, single‐strand breaks

Abstract

DNA damage was induced in isolated human peripheral lymphocytes by exposure at 5 Gy to 60Co radiation. Cells were permitted to repair the DNA damage while exposed to 60-Hz fields or while sham-exposed. Exposed cells were subjected to magnetic (B) or electric (E) fields, alone or in combination, throughout their allotted repair time. Repair was stopped at specific times, and the cells were immediately lysed and then analyzed for the presence of DNA single-strand breaks (SSB) by the alkaline-elution technique. Fifty to 75 percent of the induced SSB were repaired 20 min after exposure, and most of the remaining damage was repaired after 180 min. Cells were exposed to a 60-Hz ac B field of 1 mT; an E field of 1 or 20 V/m; or combined E and B fields of 0.2 V/m and 0.05 mT, 6 V/m and 0.6 mT, or 20 V/m and 1 mT. None of the exposures was observed to affect significantly the repair of DNA SSB.

Controversial cytogenetic observations in mammalian somatic cells exposed to extremely low frequency electromagnetic radiation: A review and future research recommendations

“…Frazier et al [1990] used Helmholtz coils that were placed inside an incubator. The repair kinetics of SSB in gamma-irradiated cells was assessed in the presence of EF, MF, or combined EMF using alkaline elution and fluorimetric analysis.…”

Decreased DNA repair rates and protection from heat induced apoptosis mediated by electromagnetic field exposure

“…Interestingly, previous studies involving DNA repair and EMF exposure have reported no effect [Cossarizza et al, 1989a;Frazier et al, 1990;Cantoni et al, 1995Cantoni et al, , 1996. However, these DNA repair studies allowed repair to occur concurrent with EMF exposure.…”

The effects of extremely low frequency magnetic fields on mutation induction in mice

“…The sensitivity of such assays had previously been reported to equate to 10-50 cGy of X-irradiation in lymphocytes (McNamee et al, 2000). Furthermore, earlier findings by Frazier et al (1990) contradict those of who reported the presence of strand breaks 4 hours after exposure to MF. Frazier and co-authors (1990) assessed the repair kinetics of DNA SSBs in the presence of 60 Hz magnetic field of 1 mT, noting that within 20 minutes of exposure between 50 to 75% of the induced SSBs had been repaired, while the majority of the remaining damage was repaired after 3 hours.…”