LONG-TERM, LOW-LEVEL EXPOSURE OF MICE PRONE TO MAMMARY-TUMORS TO 435-MHZ RADIOFREQUENCY RADIATION

The purpose of this study was to determine if chronic, low-level expos ure of mice prone to mammary tumors to 435 MHz radiofrequency (RF) rad iation promotes an earlier onset, a faster growth rate or a greater to tal incidence of mammary tumors than in sham-exposed controls. Two hun dred female C3H/HeJ mice were exposed for 21 months (22 h/day, 7 days/ week) to a horizontally polarized 435 MHz pulse-wave (1.0 mu s pulse w idth, 1.0 kHz pulse rate) RF radiation environment with an incident po wer density of 1.0 mW/cm(2) (SAR = 0.32 W/kg). An additional 200 mice were sham-exposed. Animals that died spontaneously, became moribund or were euthanized after 21 months of exposure were completely necropsie d; tissues were subjected to histopathological examinations. Concernin g mammary carcinomas, there were no significant differences between th e two groups with respect to latency to tumor onset, tumor growth rate and overall tumor incidence. Histopathological examination revealed n o significant differences in numbers of malignant, metastatic or benig n neoplasms between groups. Survival probability was estimated by the Kaplan-Meier method; no significant difference between groups was note d (Cox's test). Under the conditions of this long-term study, low-leve l exposure of mice prone to mammary tumors to 435 MHz RF radiation did not affect the incidence of mammary tumors, tumor growth rate, latenc y to tumor onset or animal longevity when compared to sham-exposed con trols. (C) 1997 by Radiation Research Society.