To investigate the possible effects of exposure to radiofrequency electromagnetic fields (GSM or continuous wave (CW)) on soybean seedlings.
Seven experiments with different exposure protocols were performed: 1.) 2 h sham exposure + 2 h GSM exposure (electric field strength 41 V/m) 2.) 2 h sham exposure + 2 h GSM exposure (5.7 V/m), 3.) 2 h sham exposure + 2 h GSM exposure (41 V/m) + 2 h sham exposure, 4.) 2 h sham exposure + 2 h GSM exposure (5.7 V/m) + 2 h sham exposure, 5.) 5 days sham exposure + 5 days GSM exposure (0.56 V/m), 6.) 2 h sham exposure + 2 h CW exposure (41 V/m) and 7.) 2 h sham exposure + 2 h CW exposure (5.7 V/m) + 2 h sham exposure. Additional seedlings were sham exposed. The experiments 1, 3, 5, 6, and 7 were conducted twice. The fifth experiment was performed to simulate base station-like conditions, i.e. long lasting but low electric field strength.
| Exposure | Parameters |
|---|---|
|
Exposure 1:
900 MHz
Modulation type:
pulsed
Exposure duration:
continuous for 2 hours
experiment 1 and 3
|
|
|
Exposure 2:
900 MHz
Modulation type:
pulsed
Exposure duration:
continuous for 2 hours
experiment 2 and 4
|
|
|
Exposure 3:
900 MHz
Modulation type:
pulsed
Exposure duration:
continuous for 5 days
experiment 5
|
|
|
Exposure 4:
900 MHz
Modulation type:
CW
Exposure duration:
continuous for 2 hours
experiment 6
|
|
|
Exposure 5:
900 MHz
Modulation type:
CW
Exposure duration:
continuous for 2 hours
experiment 7
|
|
EF values were measured with and without the petri dishes present and were found to be identical
| Frequency | 900 MHz |
|---|---|
| Type | |
| Waveform | |
| Exposure duration | continuous for 2 hours |
| Additional info | experiment 1 and 3 |
| Modulation type | pulsed |
|---|---|
| Pulse width | 0.576 ms |
| Repetition frequency | 217 Hz |
| Exposure source | |
|---|---|
| Chamber | 10 seedlings were placed in a Petri dish (nearly 2.4 cm apart) in total darkness |
| Setup | petri dish with seedlings was placed in the middle of the testing area (400 x 400 mm) in the GTEM cell; temperature in the GTEM cell (23°C) was measured at the beginning, during, and at the end of the exposure and did not vary more than ± 0.1°C; humidity level was 70% |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| electric field strength | 41 V/m | - | measured | - | - |
| power density | 560 mW/m² | average over time | - | - | - |
| power density | 4,400 mW/m² | peak value | - | - | - |
| SAR | 2.6 mW/kg | - | calculated | - | - |
| Frequency | 900 MHz |
|---|---|
| Type | |
| Waveform | |
| Exposure duration | continuous for 2 hours |
| Additional info | experiment 2 and 4 |
| Modulation type | pulsed |
|---|---|
| Pulse width | 0.576 ms |
| Repetition frequency | 217 Hz |
| Exposure source |
|---|
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| electric field strength | 5.7 V/m | - | measured | - | - |
| power density | 11 mW/m² | average over time | - | - | - |
| power density | 86 mW/m² | peak value | - | - | - |
| SAR | 0.049 mW/kg | - | calculated | - | - |
| Frequency | 900 MHz |
|---|---|
| Type | |
| Waveform | |
| Exposure duration | continuous for 5 days |
| Additional info | experiment 5 |
| Modulation type | pulsed |
|---|---|
| Pulse width | 0.576 ms |
| Repetition frequency | 217 Hz |
| Exposure source |
|---|
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| electric field strength | 0.56 V/m | - | measured | - | - |
| power density | 0.1 mW/m² | average over time | - | - | - |
| power density | 0.8 mW/m² | peak value | - | - | - |
| SAR | 0.48 µW/kg | - | calculated | - | - |
| Frequency | 900 MHz |
|---|---|
| Type | |
| Exposure duration | continuous for 2 hours |
| Additional info | experiment 6 |
| Modulation type | CW |
|---|
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| electric field strength | 41 V/m | - | measured | - | - |
| power density | 4,400 mW/m² | average over time | - | - | - |
| power density | 4,400 mW/m² | peak value | - | - | - |
| SAR | 20 mW/kg | - | calculated | - | - |
| Frequency | 900 MHz |
|---|---|
| Type | |
| Exposure duration | continuous for 2 hours |
| Additional info | experiment 7 |
| Modulation type | CW |
|---|
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| electric field strength | 5.7 V/m | - | measured | - | - |
| power density | 86 mW/m² | average over time | - | - | - |
| power density | 86 mW/m² | peak value | - | - | - |
| SAR | 0.39 mW/kg | - | calculated | - | - |
Seedlings exposed to GSM signals with an electric field strength of 41 V/m (experiments 1 and 3) showed significantly shorter epicotyls compared to sham exposed ones. No significant differences were observed between exposure to electric field strength of 5.7 V/m (experiments 2 and 4) and the sham exposure.
However, exposure of seedlings to a weak electric field strength for five days (experiment 5) resulted in significantly shorter epicotyls and hypocotyls as well as in significantly elongated roots compared to the sham exposed seedlings.
The roots of seedlings that were exposed to CW with an electric field strength of 41 V/m (experiment 6) were significantly shorter than those of the corresponding sham exposure, while in the group exposed to CW with an electric field strength of 5.7 V/m (experiment 7), the hypocotyls were significantly shortened.
The authors conclude that effects of radiofrequency electromagnetic fields on soybean seedlings depend on electric field strengths and modulation characteristics.
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