Chronic, low-level (1.0 W/kg) exposure of mice prone to mammary cancer to 2450 MHz microwaves

In a previous study (Frei et al., Bioelectromagnetics 19, 20-31, 1998), we showed that low-level (0.3 W/kg), long-term exposure of mice prone to mamma ry tumors to 2450 MHz radiofrequency (RF) radiation did not affect the inci dence of mammary tumors, latency to tumor onset, tumor growth rate or anima l survival when compared to sham-irradiated animals. In the current study, the specific absorption rate (SAR) was increased from 0.3 W/kg to 1.0 W/kg. The same biological end points were used. One hundred C3H/HeJ mice were ex posed in circularly polarized waveguides for 78 weeks (20 h/day, 7 days/wee k) to continuous-wave, 2450 MHz RF radiation; 100 mice were sham-exposed. T here was no significant difference between exposed and sham-exposed groups with respect to the incidence of palpated mammary tumors (sham-exposed = 30 %; irradiated = 38%), latency to tumor onset (sham-exposed = 62.0 +/- 2.3 w eeks; irradiated = 62.5 +/- 2.2 weeks) and rate of tumor growth. Histopatho logical evaluations revealed no significant difference in numbers of malign ant, metastatic or benign neoplasms between the two groups. Thus long-term exposures of mice prone to mammary tumors to 2450 MHz RF radiation at SARs of 0.3 and 1.0 W/kg had no significant effects when compared to sham-irradi ated animals. (C) 1998 by Radiation Research Society.