To study whether the recorded window effect (decreased reproductive capacity of insects) of a previous study (see Panagopoulos 2010) was due to the fact that the wavelengths of 900 MHz and at 1800 MHz were as long as the distances from the antenna (33 cm and 17 cm, respectively) where the window effect appeared (30 cm for 900 MHz and 20 cm for 1800 MHz) or due to the power density of 10 µW/cm².
One group of insects was exposed to 900 MHz or 1800 MHz at 30 or 20 cm distances, respectively, from the antenna of a mobile phone. Another group was exposed at 8 or 5 cm, respectively, behind a metal grid, shielding both microwave irradiation and the extremely low frequency electric and magnetic fields for both types of irradiation in a way that field intensities were roughly equal between the two groups.
Five identical experiments were performed. Each group consisted of ten female and ten male newly emerged flies kept in separate vials for the first 48 h. After the 48 h, when both males and females of each group were sexually mature, they were put together (10 pairs) in another glass vial and they were allowed to mate and lay eggs for the next 72 h.
| Exposure | Parameters |
|---|---|
|
Exposure 1:
900 MHz
Exposure duration:
continuous for 6 min/day on 5 days
|
|
|
Exposure 2:
1,800 MHz
Exposure duration:
continuous for 6 min/day on 5 days
|
|
|
Exposure 3:
900 MHz
Exposure duration:
continuous for 6 min/day on 5 days
|
|
|
Exposure 4:
1,800 MHz
Exposure duration:
continuous for 6 min/day on 5 days
|
|
| Frequency | 900 MHz |
|---|---|
| Type | |
| Exposure duration | continuous for 6 min/day on 5 days |
| Exposure source | |
|---|---|
| Setup | a dual band GSM mobile phone in speaking mode was used at a distance of 30 cm |
| Sham exposure | A sham exposure was conducted. |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| SAR | 0.89 W/kg | maximum | - | - | manufacturer's information for the human head |
| power density | 10 µW/cm² | - | measured | - | +/- 3 µW/cm² |
| electric field strength | 0.61 V/m | average over time | measured | - | +/- 0.11 V/m ELF field |
| magnetic flux density | 0.01 µT | average over time | measured | - | +/- 0.002 µT ELF field |
| Frequency | 1,800 MHz |
|---|---|
| Type | |
| Exposure duration | continuous for 6 min/day on 5 days |
| Exposure source | |
|---|---|
| Setup | a dual band GSM mobile phone in speaking mode was used at a distance of 20 cm |
| Sham exposure | A sham exposure was conducted. |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| SAR | 0.89 W/kg | maximum | - | - | manufacturer's information for the human head |
| power density | 11 µW/cm² | - | measured | - | +/- 3 µW/cm² |
| electric field strength | 0.6 V/m | average over time | measured | - | +/- 0.13 V/m ELF field |
| magnetic flux density | 0.009 µT | average over time | measured | - | +/- 0.003 µT ELF field |
| Frequency | 900 MHz |
|---|---|
| Type | |
| Exposure duration | continuous for 6 min/day on 5 days |
| Exposure source | |
|---|---|
| Setup | a dual band GSM mobile phone in speaking mode was used at a distance of 8 cm behind a ferromagnetic shielding grid |
| Sham exposure | A sham exposure was conducted. |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| SAR | 0.89 W/kg | maximum | - | - | manufacturer's information for the human head |
| power density | 10.1 µW/cm² | - | measured | - | +/- 2.8 µW/cm² |
| electric field strength | 0.65 V/m | average over time | measured | - | +/- 0.1 V/m ELF field |
| magnetic flux density | 0.012 µT | average over time | measured | - | +/- 0.003 µT ELF field |
| Frequency | 1,800 MHz |
|---|---|
| Type | |
| Exposure duration | continuous for 6 min/day on 5 days |
| Exposure source | |
|---|---|
| Setup | a dual band GSM mobile phone in speaking mode was used at a distance of 5 cm behind a ferromagnetic shielding grid |
| Sham exposure | A sham exposure was conducted. |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| SAR | 0.89 W/kg | maximum | - | - | manufacturer's information for the human head |
| power density | 10.8 µW/cm² | - | measured | - | +/- 3.2 µW/cm² |
| electric field strength | 0.66 V/m | average over time | measured | - | +/- 0.12 V/m ELF field |
| magnetic flux density | 0.013 µT | average over time | measured | - | +/- 0.002 µT ELF field |
The decrease in the reproductive capacity did not differ significantly between the two exposure groups and the reproductive capacity of each exposed group was significantly decreased compared to the sham exposed group. Thus, this window effect is only indirectly related to the distance from the antenna; it does not seem to be related to the wavelength (or the frequency) of the irradiation. This "window" was directly dependent on the intensity of the field, no matter on which distance from the antenna this intensity exists.
The authors conclude that the bioactivity window effect seemed to be due to the intensity of the incident field (10 µW/cm², 0.6-0.7 V/m) at 30 or 20 cm from the GSM 900 or 1800 mobile phone antenna, respectively.
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