The effects of 860 MHz radiofrequency radiation on the induction or promotion of brain tumors and other neoplasms in rats

Sprague-Dawley rats were irradiated with a continuous-wave(CW) or a pulsed- wave (P) radiofrequency (RF) for 6 h/day, 5 days/week from 2 up to 24 month s of age. The RFs emanated from dipole antennas (2 W average output) 2.0 +/ - 0.5 cm from the tip of each rat's nose. The RFs had an 860 MHz frequency, and the specific absorption rate was 1.0 W/ kg averaged over the brain. Fi fteen groups of 60 rats (900 total) were formed from offspring of females i njected i.v. with 0 (groups 1, 2, 9, 10, 13), 2.5 (groups 5, 6, 7, 8, 11, 1 2, 14) or 10 mg/kg (groups 3, 4, 15) ethylnitrosourea (ENU) to induce brain tumors. Groups 1, 3, 5 and 7 received the PRF, and groups 9 and 11 the CWR F; groups 2, 4, 6, 8, 10 and 12 were sham-irradiated, and groups 13-15 were cage controls. Au rats but 2, totaling 898, were necropsied, and major tis sues were studied histopathologically. There was no statistically significa nt evidence that the PRF or CWRF induced neoplasia in any tissues. Addition ally, there was no significant evidence of promotion of cranial or spinal n erve or spinal cord tumors. The PRF or CWRF had no statistically significan t effect on the number, volume, location, multiplicity, histological type, malignancy or fatality of brain tumors. There was a trend for the group tha t received a high dose of ENU and was exposed to the PRF to develop fatal b rain tumors at a higher rate than its sham group; however, the result was n ot significant using the log-rank test (P = 0.14, 2-tailed). No statistical ly significant differences were related to the PRF or CWRF compared to cont rols in the low or zero dose groups regarding tumors of any kind. (C) 2001 by Radiation Research Society.