500 rats were treated with a single dose of 35 mg/kg DMBA and exposure started on the day after DMBA administration.
This study was a parallel project to one part of the PERFORM-A program (International EMF project launched by WHO).
|Chamber||The rats where exposed in 12 air-conditioned radial exposure units called wheels, each holding 17 rats. Each week, the exposure positions of each rat on the wheel were rotated one position to the right.|
|Setup||The exposure wheel consisted of a circular cascade of 17 sectored waveguides, all of which were excited by one quarter-loop antenna located in the center and providing uniform circular excitation. The rats were restrained in a horizontal position in metal-free polycarbonate tubes inside the waveguide cavity ventilated from the front where the head of the rat was located.|
|Sham exposure||A sham exposure was conducted.|
|Additional info||Exposure was based on a novel concept using H-polarization to provide reasonable homogeneity of exposure for rats of different sizes.|
No significant differences in overall mammary tumor incidence, latency to tumor onset, tumor multiplicity, or tumor size were revealed between exposed and sham exposed groups. Additionally, there were no statistically significant differences in body weight.
There was a tendency for reduction of mammary adenocarcinoma incidence in the lowest exposure group (0.44 W/ kg) compared with the sham exposed rats. Additionally, a higher incidence of adenocarcinoma was noticed in the 4.0 W/kg animals from the 15th to 26th weeks. However, neither tendency was statistically significant; thus this study does not provide evidence that GSM microwave exposure promotes mammary tumor development in rats.
There were significant differences between the cage controls and the experimental groups (sham exposure and exposure). Body weight and mammary tumor incidence in the cage control animals were significantly higher than in the sham exposed and exposed rats. The latency to the mammary tumor onset was significantly shorter in the cage control animals than in the other animals.