DNA and chromosomal damage in response to intermittent extremely low-frequency magnetic fields

Considerable controversy still exists as to whether electric and magnetic fields (MF) at extremely low frequencies are genotoxic to humans. The aim of this study was to test the ability of alternating magnetic fields to induce DNA and chromosomal damage in primary human fibroblasts. Single- and double-strand breaks were quantified using the alkaline comet assay and the γH2AX-foci assay, respectively. Chromosomal damage was assayed for unstable aberrations, sister chromatid exchange and micronuclei. Cells were exposed to switching fields - 5 min on, 10 min off - for 15 h over the range 50-1000 μT. Exposure to ionizing radiation was used as a positive-effect calibration. In this study two separate MF exposure systems were used. One was based on a custom-built solenoid coil system and the other on a commercial system almost identical to that used in previous studies by the EU REFLEX programme. With neither system could DNA damage or chromosomal damage be detected as a result of exposure of fibroblasts to switching MF. The sensitive γH2AX assay could also not detect significant DNA damage in the MF-exposed fibroblasts, although the minimum threshold for this assay was equivalent to an X-ray dose of 0.025 Gy. Therefore, with comparable MF parameters employed, this study could not confirm previous studies reporting significant effects for both the alkaline and neutral comet assays and chromosomal aberration induction.