Study type: Medical/biological study (experimental study)

Hsp70 expression and free radical release after exposure to non-thermal radio-frequency electromagnetic fields and ultrafine particles in human Mono Mac 6 cells. med./bio.

Published in: Toxicol Lett 2006; 161 (1): 73-82

Aim of study (acc. to author)

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.

Background/further details

Heat treatment (42-43°C, 1h) was used as positive control for both stress reaction and for heat development in the radiofrequency exposure setup.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 1,800 MHz
Modulation type: CW
Exposure duration: continuous for 60 min
  • SAR: 2 W/kg unspecified
Exposure 2: 1,800 MHz
Modulation type: pulsed
Exposure duration: continuous for 60 min
  • SAR: 2 W/kg unspecified
Exposure 3: 1,800 MHz
Modulation type: pulsed
Exposure duration: continuous for 60 min
GSM non-DTX signal
  • SAR: 2 W/kg unspecified

General information

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.

Exposure 1

Main characteristics
Frequency 1,800 MHz
Type
Charakteristic
  • guided field
Exposure duration continuous for 60 min
Modulation
Modulation type CW
Exposure setup
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.
Parameters
Measurand Value Type Method Mass Remarks
SAR 2 W/kg unspecified unspecified - -

Exposure 2

Main characteristics
Frequency 1,800 MHz
Type
Charakteristic
  • guided field
Exposure duration continuous for 60 min
Modulation
Modulation type pulsed
Pulse width 0.576 ms
Duty cycle 12.5 %
Repetition frequency 217 Hz
Pulse type rectangular
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
SAR 2 W/kg unspecified unspecified - -

Exposure 3

Main characteristics
Frequency 1,800 MHz
Type
Charakteristic
  • guided field
Exposure duration continuous for 60 min
Additional info GSM non-DTX signal
Modulation
Modulation type pulsed
Pulse width 0.576 ms
Duty cycle 12.5 %
Repetition frequency 217 Hz
Pulse type rectangular
Additional info

GSM non-DTX signal with every 26th frame idle, which added an 8 Hz modulation component to the signal. The crest factor (ratio of pulse power and average power) was 8.3.

Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
SAR 2 W/kg unspecified unspecified - -

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

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.

Study character:

Study funded by

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