The preliminary results of a new pilot study, conducted at ITEM, Hannover, and presented at the 17th FGF Workshop in Berlin last week, showed distinct tumor-promoting effects of chronic UMTS exposure (20 hours/day, 7 days/week, 24 months) beginning at the fetal stage in the offspring of ENU-treated mice. The exposure was performed in a three-level exposure unit (sham, medium-dose, high-dose) consisting of three stacked radial waveguides and housing up to 60 female B6C3F1 mice (3 per cage) per level. Additionally, an untreated cage control group and a positive (ENU-treated) control group were evaluated. Histopathological examination by light microscopy was limited to the brain, lungs, liver, spleen, kidneys, mesenterial lymph nodes, and gross lesions. Mortality in both ENU groups increased after 12 months lifetime, confirming the effectiveness of the prenatal/maternal ENU treatment. Cage controls, sham, and the UMTS exposed mice showed similar mortality rates up to terminal sacrifice (week 104). The cage control group, sham exposure group and UMTS high-dose group revealed comparable tumor incidences in the target organs. The UMTS high-dose group, however, showed a significantly increased number of pre-neoplastic liver foci as compared to the sham control and cage control groups. Analysis of the neoplastic and preneoplastic findings in the two ENU groups revealed (1) an increased liver tumor rate and a significantly increased lung tumor incidence in the ENU/UMTS group as compared to the ENU control group, (2) increased incidences of hepatocellular adenomas and bronchioloalveolar carcinomas in the ENU groups after lifetime UMTS exposure, (3) a significant increase in hepatocellular adenoma and bronchioloalveolar carcinoma multiplicity in the ENU/UMTS group as compared to the ENU control group, (4) a doubling of the incidence of metastasizing lung carcinomas in the two ENU groups by the long-term UMTS exposure, and (5) a significant increase in the incidence of preneoplastic hepatocellular foci in the ENU/UMTS group as compared to the ENU control group.
These results will be difficult to interpret and assess since the majority of previous studies have focused on GSM-like exposures. The specificity of the applied exposure must be carefully analyzed before well targeted investigations are initiated to confirm these findings and to corroborate their relevance to human health.