Cytogenetic damage in adult and newborn mice exposed to Elf magnetic fields

Data obtained in newborn mice show that the chronic exposure during intra-uterine life to a 50 Hz, 650 μT E.L.F. magnetic field induce a genetic damage. Nevertheless, the increase of DNA strand break in brain and in micronuclei frequency in peripheral blood and liver disagree with the data obtained by Abramsson-Zetterberg and Grawe (13) which did not find any genetic alterations in mice exposed to extremely low frequency (E.L.F.) magnetic field. In any case, along with other dissimilarities in the experimental design, the intensity of the field (14 μT) and the time of sampling (35 days) were different. It is important to underline the four-fold increase in C.R.E.S.T.+ micronuclei frequency in circulating erythrocytes in the exposed group in comparison with the control group. Even though this value is quite low, it could indicate that E.L.F. magnetic fields may have different properties to damage the genome integrity. This stresses the need for further investigation on the possible link between electromagnetic fields and aneuploidy in order to elucidate the relationship with carcinogenesis. Preliminary data obtained with sperm abnormality assay show a significant increase of sperm abnormalities in mice exposed to E.L.F. magnetic fields and suggest a possible alteration to the spermatogenic process after exposure. This data agrees with data obtained by Tablado et al. (1998), in mice exposed continually for 35 days to a field of 1 T. Regarding the palatal ridges alterations assay, the results obtained show that the development of the secondary palate is not affected by E.L.F. magnetic field (50 Hz, 0,65 T). Nevertheless further studies at different frequency and intensity should be carried out to detect the possible epigenetic damage induced by E.L.F. exposure (Migliorini, 2005). With regard to the mechanism of action, it is generally believed that the damage induced by the magnetic field is an oxidative damage and that free radicals are involved. Some authors suggest that the Fe2+ ion is involved as catalyzer of the Fenton reaction producing the hydroxyl radical. Lai and Singh (1997a; 1997b; 2004) found DNA strand breaks in brain cells of rats exposed to 60 Hz magnetic field and showed the involvement of free radicals. These authors showed that the effects of the E.L.F. magnetic fields on the production of reactive oxygen species (R.O.S.) determine their clastogenic properties. By the way, it should be noted that R.O.S. interactions with the spindle apparatus can result in aneuploidy. (N.C.)