Effects of 50 Hz magnetic fields on UV-induced skin tumourigenesis in ODC-transgenic and non-transgenic mice

Abstract

Abstract. Purpose: To study the possible role of 50 Hz magnetic fields (MF) in UV-induced skin tumourigenesis using a sensitive animal model. Materials and methods: Transgenic mice (line K2) over-expressing the human ornithine decarboxylase (ODC) gene and their nontransgenic littermates were exposed for 10.5 months to UV-only or a combination of UV and a continuous (100 mu T) or an intermittent MF with varying intensity (1.3-130 mu T). Results: Both MF exposure and transgenicity enhanced the onset rate of macroscopically detectable tumours, but the effect was statistically significant only for the MF exposure (p 0.015). The number of animals bearing malignant tumours was low and similar in all exposure groups. Epidermal cysts (EC) appeared to be strongly associated with both MF exposure and high ODC activity (transgenic animals). However, EC are not known to be associated with carcinogenesis. The UV-only or combined UV and MF exposure did not affect the ODC activities measured at the end of the exposure. Conclusions: These results support the proposed tumour-promoting effect of MF, but do not suggest an important role for increased ODC activity in this process.