This is so far the largest long-term study ever performed in rats on the health effects of radiofrequency fields, including 2,448 animals. The study can be regarded as complementary to the long-term study conducted by the NTP (NTP, 2018), which used near field exposure and significantly higher field strengths. In this article, only the partial results for heart and brain are presented, further results will be published in the future.
Four groups of rats were examined: 1) exposure to 5 V/m (male n=401, female n=410), 2) exposure to 25 V/m (male n=209, female n=202), 3) exposure to 50 V/m (male n=207, female n=202), 4) sham exposure (male n=412, female n=405).
|Exposure 1: 1,835 MHz|
|Exposure 2: 1,835 MHz|
|Exposure 3: 1,835 MHz|
|Chamber||rats of each group were located in separate rooms with the same environmental conditions (i.e., temperature of 22 ± 3°C, a relative humidity of 40–60% and 12 h/day homogeneous illumination); rooms were totally shielded with RF absorbing material and ensured a minimum insulation of 30 dB; 5 rats were housed in one polycarbonate cage, respectively|
|Setup||each single exposure device served at least 400 rats; rat cages were located in wooden circular-shaped devices on several levels up to a height of about 1.6 m; each level formed a ring at a distance of about 2 m from the antenna in the center; a collinear antenna (a phased array of stacked dipoles) was able to transmit a homogeneous far field with cylindrical distribution of the field strength (field uniformity better than 3 dB); the output levels were controlled with a closed loop control system, able to stabilize the field in an uncertainty level of 1 dB range|
|Sham exposure||A sham exposure was conducted.|
A statistically significant increase in the incidence of heart schwannomas was observed in male rats exposed to a electromagnetic field of 50 V/m (group 3) compared to the sham exposure group. Moreover, an increase in the incidence of heart Schwann cells hyperplasia in male and female rats of group 3 and malignant glial tumors of the brain in female rats of group 3 was observed in comparison to the sham exposure but was not statistically significant.
No differences were found in mean food and water consumption, body weight or survival rate, either in male or in female rats, between the groups.
The authors conclude that livelong far field exposure to 1.8 GHz electromagnetic fields could increase the incidence of tumors in the heart and possibly also in the brain of rats. These results are consistent with and reinforce the results of the NTP study on near field exposure.