A total of 72 animals were used in this study (divided into two groups/36 animals each). One group was MF-exposed, the other one served as sham-exposed control. Each animal obtained an initial oral administration of 5 mg DMBA prior the onset of exposure/sham-exposure. DMBA administration was repeated weekly up to a total dose of 20 mg.
No significant differences between groups were found in general behavior, body weight, or weight of spleen and liver. Also histopathological examination of tumors did not reveal any significant differences between the MF-exposed and the sham-exposed group. However, nocturnal melatonin serum levels were significantly reduced in the MF-exposed group.