  Extremely low frequency electromagnetic fields aren't considered as a real
carcinogenic agent despite the fact that some studies have showed impairment of
the DNA integrity in different cells lines. The aim of this study was
evaluation of the late effects of a 100 Hz and 5.6 mT electromagnetic field,
applied continuously or discontinuously, on the DNA integrity of Vero cells
assessed by alkaline Comet assay and by cell cycle analysis. Normal Vero cells
were exposed to extremely low frequency electromagnetic fields (100 Hz, 5.6 mT)
for 45 minutes. The Comet assay and cell cycle analysis were performed 48 hours
after the treatment. Exposed samples presented an increase of the number of
cells with high damaged DNA as compared with non-exposed cells. Quantitative
evaluation of the comet assay showed a significantly ($<$0.001) increase of the
tail lengths, of the quantity of DNA in tail and of Olive tail moments,
respectively. The analysis of the registered comet indices showed that an
extremely low frequency electromagnetic field of 100 Hz and 5.6 mT had a
genotoxic impact on Vero cells. Cell cycle analysis showed an increase of the
frequency of the cells in S phase, proving the occurrence of single strand
breaks. The most probable mechanism of induction of the registered effects is
the production of different types of reactive oxygen species.
