To study if exposure to ultrafine particles (12-14 nm, 100 µg/ml) and radiofrequency electromagnetic fields (continuous wave (CW) or modulated (217 Hz or GSM-non DTX (switched-off GSM-DTX mode))), alone or in combination influences levels of the superoxide radical anion or the stress protein heat-shock protein (HSP70) in the human monocyte cell line Mono Mac 6.
Heat treatment (42-43°C, 1h) was used as positive control for both stress reaction and for heat development in the radiofrequency exposure setup.
Exposure | Parameters |
---|---|
Exposure 1:
1,800 MHz
Modulation type:
CW
Exposure duration:
continuous for 60 min
|
|
Exposure 2:
1,800 MHz
Modulation type:
pulsed
Exposure duration:
continuous for 60 min
|
|
Exposure 3:
1,800 MHz
Modulation type:
pulsed
Exposure duration:
continuous for 60 min
|
|
Cells were treated in parallel as follows: non-treated (incubator control); sham exposed; RF exposed; sham + UFP; RF + UFP; and exposed to heat (42-43 °C) (positive control). UFP stands for ultrafine particles (<0.1 µm) produced by combustion processes. In this study, UFP of 12-14 nm (100 µg/ml) were used.
Frequency | 1,800 MHz |
---|---|
Type | |
Charakteristic |
|
Exposure duration | continuous for 60 min |
Modulation type | CW |
---|
Exposure source | |
---|---|
Chamber | The RF exposure setup described in the reference article consisted of two single-mode resonator cavities (equipped with a fan) that were placed in an incubator with a humidified atmosphere of 5% CO2 in air maintained at 37 °C. |
Setup | Six 35 mm Petri dishes per cavity were placed in a dish holder positioning them in the H-field maxima of the standing waves. |
Additional info | Exposure and sham conditions were blindly assigned to the two cavities by the computer controlled signal unit. The temperature difference between sham and field exposed cultures never exceeded 0.3 °C. The incubator controls and the heat-treated samples were placed in the same incubator but outside of the cavities. |
Measurand | Value | Type | Method | Mass | Remarks |
---|---|---|---|---|---|
SAR | 2 W/kg | unspecified | unspecified | - | - |
Frequency | 1,800 MHz |
---|---|
Type | |
Charakteristic |
|
Exposure duration | continuous for 60 min |
Modulation type | pulsed |
---|---|
Pulse width | 0.576 ms |
Duty cycle | 12.5 % |
Repetition frequency | 217 Hz |
Pulse type | rectangular |
Exposure source |
|
---|
Measurand | Value | Type | Method | Mass | Remarks |
---|---|---|---|---|---|
SAR | 2 W/kg | unspecified | unspecified | - | - |
Exposure source |
|
---|
Measurand | Value | Type | Method | Mass | Remarks |
---|---|---|---|---|---|
SAR | 2 W/kg | unspecified | unspecified | - | - |
The data showed that the cells are capable to internalise ultrafine particles, and that this phagocytic activity is connected to an increased release of free radicals. This increase (40-45% above negative control) was stronger than the effect of heat treatment.
None of the employed radiofrequency exposures showed any effects on free radical levels.
Co-exposure of radiofrequency and ultrafine particles did not potentiate the ultrafine particles effect either.
The results revealed a significantly increased HSP70 expression level by heat treatment in a time-dependent manner, whereas ultrafine particles, radiofrequency, or ultrafine particles + radiofrequency were without any effect. Therefore, the authors conclude that in the investigated Mono Mac 6 cells, radiofrequency irradiation alone or in combination with ultrafine particles cannot influence stress-related responses.
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