Study type: Medical/biological study (experimental study)

Free radical release and HSP70 expression in two human immune-relevant cell lines after exposure to 1800 MHz radiofrequency radiation. med./bio.

Published in: Radiat Res 2006; 165 (1): 88-94

Aim of study (acc. to author)

To study whether 1800 MHz radiofrequency electromagnetic field exposure at nonthermal level causes production of free radicals and/or expression of heat shock proteins in exponentially growing human immune-relevant cell systems.

Background/further details

Heat shock proteins function as molecular chaperones to protect cells from stress by inhibiting free radical formation.
Free radical release was examined after exposure to incubator control, sham exposure, radiofrequency electromagnetic fields, PMA (to activate cells through the receptor-independent pathway), LPS (to study the receptor-dependent pathway), heat (40 or 42°C) or co-exposure conditions.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 1,800 MHz
Modulation type: CW
Exposure duration: continuous for 45 min
  • SAR: 0.5 W/kg average over time
  • SAR: 1 W/kg average over time
  • SAR: 1.5 W/kg average over time
  • SAR: 2 W/kg average over time
Exposure 2: 1,800 MHz
Modulation type: pulsed
Exposure duration: continuous for 45 min
GSM-nonDTX
  • SAR: 0.5 W/kg average over time
  • SAR: 1 W/kg average over time
  • SAR: 1.5 W/kg average over time
  • SAR: 2 W/kg average over time
Exposure 3: 1,800 MHz
Modulation type: pulsed
Exposure duration: continuous for 45 min or 1 h (HSP70 expression)
  • SAR: 0.5 W/kg average over time
  • SAR: 1 W/kg average over time
  • SAR: 1.5 W/kg average over time
  • SAR: 2 W/kg average over time (also used in HSP70 expression experiment)
Exposure 4: 1,800 MHz
Modulation type: pulsed
Exposure duration: continuous for 45 min
  • SAR: 0.5 W/kg average over time
  • SAR: 1 W/kg average over time
  • SAR: 1.5 W/kg average over time
  • SAR: 2 W/kg average over time

General information

Cells were treated concurrently in the same incubator as follows: (1) non-treated (incubator control), (2) sham exposed, (3) RF EMF exposed, (4) sham exposed + 1 µg/ml LPS or 1 µM PMA, (5) co-exposed to RF EMF + LPS or PMA, or (6) exposed to heat (40°C or 42°C) in a separate incubator. Exposures to different SARs or signal-modulated conditions were performed separately. All experiments were carried out for 45 min at 37°C (except for the heat experiment) in a humidified atmosphere of 5% CO2 in air.

Exposure 1

Main characteristics
Frequency 1,800 MHz
Type
Charakteristic
  • guided field
Exposure duration continuous for 45 min
Modulation
Modulation type CW
Exposure setup
Exposure source
Chamber The exposure setup (see reference article) consisted of two single-mode resonator cavities that were placed within the CO2 incubator. Each waveguide was equipped with a fan and monopole field sensors.
Setup Six 35-mm Petri dishes were exposed in one waveguide, and a dish holder ensured the correct placement of the dishes in the H-field maxima of the standing waves inside the cavity.
Sham exposure A sham exposure was conducted.
Additional info Exposure and sham conditions were blindly assigned to the two waveguides by the computer-controlled signal unit. Field strengths, air temperatures, fan driving currents and all commands were continuously logged. During exposure, the temperature difference between sham and field exposed cultures never exceeded 0.3°C. As shown by numerical simulation, the possibility of temperature hot spots can be excluded.
Parameters
Measurand Value Type Method Mass Remarks
SAR 0.5 W/kg average over time measured and calculated - -
SAR 1 W/kg average over time measured and calculated - -
SAR 1.5 W/kg average over time measured and calculated - -
SAR 2 W/kg average over time measured and calculated - -

Exposure 2

Main characteristics
Frequency 1,800 MHz
Type
Charakteristic
  • guided field
Exposure duration continuous for 45 min
Additional info GSM-nonDTX
Modulation
Modulation type pulsed
Pulse width 0.576 ms
Duty cycle 12.5 %
Repetition frequency 217 Hz
Pulse type rectangular
Additional info

GSM-nonDTX (speaking only): Basic frame with every 26th frame idle, which adds an 8 Hz component to the signal. The crest factor is 8.3.

Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 0.5 W/kg average over time measured and calculated - -
SAR 1 W/kg average over time measured and calculated - -
SAR 1.5 W/kg average over time measured and calculated - -
SAR 2 W/kg average over time measured and calculated - -

Exposure 3

Main characteristics
Frequency 1,800 MHz
Type
Charakteristic
  • guided field
Exposure duration continuous for 45 min or 1 h (HSP70 expression)
Additional info GSM-DTX
Modulation
Modulation type pulsed
Pulse width 0.576 ms
Duty cycle 12.5 %
Repetition frequency 217 Hz
Pulse type rectangular
Additional info

GSM-DTX (hearing only): Is activated during periods of not speaking into the phone. The transmission is reduced to 12 active frames per 104 frames, leading to a crest factor of 69. The frame structure results in 2, 8 and 217 Hz components.

Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 0.5 W/kg average over time measured and calculated - -
SAR 1 W/kg average over time measured and calculated - -
SAR 1.5 W/kg average over time measured and calculated - -
SAR 2 W/kg average over time measured and calculated - also used in HSP70 expression experiment

Exposure 4

Main characteristics
Frequency 1,800 MHz
Type
Charakteristic
  • guided field
Exposure duration continuous for 45 min
Additional info GSM-Talk
Modulation
Modulation type pulsed
Pulse width 0.576 ms
Duty cycle 12.5 %
Repetition frequency 217 Hz
Pulse type rectangular
Additional info

GSM-Talk (34% speaking and 66% hearing): Simulates a conversation and generates temporal changes between 11 s of GSM-nonDTX and 6 s of GSM-DTX (average durations). The crest factor is 11.9.

Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 0.5 W/kg average over time measured and calculated - -
SAR 1 W/kg average over time measured and calculated - -
SAR 1.5 W/kg average over time measured and calculated - -
SAR 2 W/kg average over time measured and calculated - -

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated material:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

Heat and PMA treatment induced a significant increase in superoxide radical anions and in reactive oxygen species production in the Mono Mac 6 cells when compared to sham exposure and/or incubator conditions.
In Mono Mac 6 cells or K562 cells no significant differences in free radical production were found after radiofrequency electromagnetic field exposure or in the respective controls. No additional effects on superoxide radical anion production were revealed after co-exposure to "radiofrequency electromagnetic fields+PMA" or "radiofrequency electromagnetic fields+LPS".
No significant effects were detected in HSP70 expression levels after different radiofrequency electromagnetic field exposures.

Study character:

Study funded by

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