EFFECTS OF 50 HZ MAGNETIC-FIELDS ON UV-INDUCED SKIN TUMORIGENESIS IN ODC-TRANSGENIC AND NONTRANSGENIC MICE

Purpose: To study the possible role of 50 Hz magnetic fields (MF) in U V-induced skin tumourigenesis using a sensitive animal model. Material s ann Methods: Transgenic mice (line K2) over-expressing the human orn ithine decarboxylase (ODC) gene and their non transgenic littermates w ere exposed for 10.5 months to UV-only or a combination of UV and a co ntinuous (100 mu T)) or an intermittent MF with varying intensity (1.3 -130 mu T). Results: Both NF exposure and transgenicity enhanced the o nset rate of macroscopically detectable tumours, but the effect was st atistically significant only for the MF exposure (p<0.015). The number of animals bearing malignant tumours was low and similar in all expos ure groups. Epidermal cysts (EC) appeared to be strongly associated wi th both MF exposure and high ODC activity (transgenic animals). Howeve r, EC are not known to be associated with carcinogenesis. The UV-only or combined UV and MF exposure did not affect the ODC activities measu red at the end of the exposure. Conclusions: These results support the proposed tumour-promoting effect of MF, but do not suggest an importa nt role for increased ODC activity in this process.