LYMPHOMAS IN E-MU-PIM1 TRANSGENIC MICE EXPOSED TO PULSED 900 MHZ ELECTROMAGNETIC-FIELDS

Whether radiofrequency (RF) fields are carcinogenic is controversial; epidemiological data have been inconclusive and animal tests limited. The aim of the present study was to determine whether long-term exposu re to pulse-modulated RF fields similar to those used in digital mobil e telecommunications would increase the incidence of lymphoma in E mu- Pim1 transgenic mice, which are moderately predisposed to develop lymp homa spontaneously. One hundred female E mu-Pim1 mice were sham-expose d and 101 were exposed for two 30-min periods per day for up to 18 mon ths to plane-wave fields of 900 MHz with a pulse repetition frequency of 217 Hz and a pulse width of 0.6 ms. Incident power densities were 2 .6-13 W/m(2) and specific absorption rates were 0.008-4.2 W/kg, averag ing 0.13-1.4 W/kg. Lymphoma risk was found to be significantly higher in the exposed mice than in the controls (OR = 2.4, P = 0.006, 95% CI = 1.3-4.5). Follicular lymphomas were the major contributor to the inc reased tumor incidence. Thus long-term intermittent exposure to RF fie lds can enhance the probability that mice carrying a lymphomagenic onc ogene will develop lymphomas. We suggest that such genetically cancer- prone mice provide an experimental system for more detailed assessment of dose-response relationships for risk of cancer after RF-field expo sure. (C) 1997 by Radiation Research Society.