To study the effect of low level radiofrequency (112 MHz amplitude modulated at 16 Hz) and 2.45 GHz exposures on mice sensitized to tumor initiated by DMBA or transplanted with ascites carcinoma cells.
The study was divided into two parts. Part A: a single dose of the chemical carcinogen DMBA (100 µg/animal) was applied on the skin of the mice and were exposed to 112 MHz or to 2.45 GHz (2 h/day, 3 days/week for 16 weeks). In part A seven groups (n=18) were included: 1) sham exposure group, 2) DMBA group, 3) DMBA + 112 MHz exposure group, 4) DMBA + 2.45 GHz exposure group, 5) 112 MHz exposure group, 6) 2.45 GHz exposure group, 7) positive control: DMBA + croton oil (i.e. with TPA, as tumor promoter).
Part B: mice were transplanted intraperitoneally with ascites carcinoma cells (Ehrlich-Lettre ascites, strain E; 8 x 108 per mouse). These mice were exposed to 112 MHz or 2.45 GHz for a period of 14 days. The following groups (n=8) were included: two different sham exposure groups, 112 MHz exposure group, and 2.45 GHz exposure group.
| Exposure | Parameters |
|---|---|
|
Exposure 1:
112 MHz
Modulation type:
AM
Exposure duration:
experiment A: continuous for 2 h/day, 3 days/week for 16 weeks; Experiment B: continuous for 2 h/day for 14 days
|
|
|
Exposure 2:
2.45 GHz
Exposure duration:
experiment A: continuous for 2 h/day, 3 days/week for 16 weeks; experiment B: continuous for 2 h/day on 14 days
|
|
animals used in the experiments A and B were divided into several groups: experiment A: i) sham exposure ii) application of a single dose of 7,12-dimethylbenz(a)anthracene (DMBA) iii) application of a single dose of DMBA + exposure to 112 MHz electromagnetic field iv) application of a single dose of DMBA + exposure to 2.45 GHz electromagnetic field v) exposure to 112 MHz electromagnetic field vi) exposure to 2.45 GHz electromagnetic field vii) application of a single dose of DMBA + tumor promoter experiment B: i) sham exposure to 112 MHz ii) exposure to 112 MHz iii) sham exposure to 2.45 GHz iv) exposure to 2.45 GHz
| Frequency | 112 MHz |
|---|---|
| Type | |
| Exposure duration | experiment A: continuous for 2 h/day, 3 days/week for 16 weeks; Experiment B: continuous for 2 h/day for 14 days |
| Modulation type | AM |
|---|---|
| Modulation frequency | 16 Hz |
| Exposure source | |
|---|---|
| Setup | two mice placed in a 32 cm x 10 cm x 9 cm Plexiglas cage, positioned in the center of the rectangular TEM cell |
| Sham exposure | A sham exposure was conducted. |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| power density | 1 mW/cm² | - | calculated | - | - |
| SAR | 0.75 W/kg | - | - | - | - |
| Frequency | 2.45 GHz |
|---|---|
| Type | |
| Exposure duration | experiment A: continuous for 2 h/day, 3 days/week for 16 weeks; experiment B: continuous for 2 h/day on 14 days |
| Exposure source | |
|---|---|
| Setup | anechoic chamber made of wood; 9 mice placed in pre-specified compartments of a 43 cm x 27 cm x 15 cm Plexiglas cage; cage placed in the anechoic chamber |
| Sham exposure | A sham exposure was conducted. |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| power density | 0.34 mW/cm² | - | calculated | - | - |
| SAR | 0.1 W/kg | - | - | - | for a small mouse |
The data did not show any statistically significant differences in the overall skin tumor incidence, latency to skin tumor onset, number of tumors per tumor bearing mice, or tumor size between the 112 MHz or 2.45 GHz exposure and sham exposure groups. Similarly, an application of a single dose of DMBA followed by 112 MHz or 2.45 GHz exposure also did not produce any visible extra tumors on the skin of mice.
On the other hand, mice transplanted with ascites carcinoma cells showed a slight increase in the cell numbers as compared to the control group. However, the increase was insignificant.
These data show that low level radiofrequency or microwave exposure do not alter tumor growth and development.
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