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Medical/biological study (experimental study)

The effects of 884 MHz GSM wireless communication signals on headache and other symptoms: an experimental provocation study.

Published in: Bioelectromagnetics 2008; 29 (3): 185-196

Aim of study (acc. to author)

To study whether exposure to radiofrequency caused by cell phone use has any acute effect on self-reported symptoms (e.g. headache, vertigo) and whether subjects are able to accurately detect the correct exposure status (exposure vs. sham exposure).
Background/further details: The study group consisted of 71 subjects (age 18-45) including 38 subjects reporting headache or vertigo in relation to cell phone use (symptom group) and 33 non-symptomatic subjects (control group).

Endpoint

Exposure

Exposure Parameters
Exposure 1: 884 MHz
Modulation type: pulsed
Exposure duration: continuous for 3 h
  • SAR: 1.4 W/kg average over time (10 g) (spatial peak for all head tissues)
  • SAR: 1.8 W/kg average over time (1 g) (spatial peak for grey matter)
  • SAR: 0.2 W/kg average over mass (brain) (± 0.26 W/kg grey matter)
  • SAR: 0.18 W/kg average over mass (brain) (e: ± 0.21 W/kg white matter d: ± 0,21 W/kg weiße Substanz)
  • SAR: 0.18 W/kg average over mass (brain) (± 0.06 W/kg thalamus)
General information
The study followed a double blind, cross-over provocation design testing exposure versus sham. The exposure setup was designed to expose all those head tissues that are exposed in daily phone usage, taking into account the range of phone designs, reasonable phone positions and head anatomies [Kuster et al., 2004], and the exposure was also intended to provide a similar tissue specific exposure distribution as applied by Huber et al. [2002].
Exposure 1
Main characteristics
Frequency 884 MHz
Type
Exposure duration continuous for 3 h
Modulation
Modulation type pulsed
Pulse width 0.577 ms
Additional info The GSM signal with a basic frame of 4.6 ms consisted of temporal changes between non-DTX and DTX modes and included all coherent ELF amplitude modulation components of 2, 8, 217, and 1736 Hz.
Exposure setup
Exposure source
Chamber Two subjects participating in each session were seated in two adjacent unshielded rooms (5.1 m x 3.6 m and 5.1 m x 2.5 m, respectively) with RF absorbers placed on three sides. The exposure conditions were set to be the same for both participants during a session in order to avoid an influence of any possible leakage of fields.
Setup The exposure apparatus consisted of a balanced headset positioning a low-weight, stacked micro patch antenna on the left side of the subject's head.
Sham exposure A sham exposure was conducted.
Additional info To mimic the sensation caused by the active phone, a small ceramic plate connected to the left ear lobe was heated to 39 ± 0.2 °C by a laser during all exposure sessions.
Parameters
Measurand Value Type Method Mass Remarks
SAR 1.4 W/kg average over time measured and calculated 10 g spatial peak for all head tissues
SAR 1.8 W/kg average over time measured and calculated 1 g spatial peak for grey matter
SAR 0.2 W/kg average over mass measured and calculated brain ± 0.26 W/kg grey matter
SAR 0.18 W/kg average over mass measured and calculated brain e: ± 0.21 W/kg white matter d: ± 0,21 W/kg weiße Substanz
SAR 0.18 W/kg average over mass measured and calculated brain ± 0.06 W/kg thalamus
Additional parameter details
The non-DTX mode with every 26th basic frame idle was set to a 10-g averaged peak spatial SAR (psSAR10g) of 1.95 W/kg. The DTX mode active during listening resulted in a reduced time-averaged psSAR10g of only 12% of the non-DTX mode. The temporal change was random with an average duration of 11 s for non-DTX and 5 s for DTX resulting in a time-averaged psSAR10g of 1.4 W/kg.
Measurement and calculation details
Numerical dosimetry was conducted with SEMCAD software and verified by measurements using DASY4 and the latest probe technology on a SAM head filled with tissue simulating liquid. Detailed dosimetric results were obtained following the methodology outlined in [Kuster et al., 2006]. In addition, the inter-subject variations as well as assessment uncertainty were estimated. The basic numerical head model was derived from 121 magnetic resonance images of a 40-year European female and distinguished 23 tissues.
Reference articles
  • Kuster N et al. (2006): Methodology of detailed dosimetry and treatment of uncertainty and variations for in vivo studies.
  • Kuster N et al. (2004): Guidance for exposure design of human studies addressing health risk evaluations of mobile phones.
  • Huber R et al. (2002): Electromagnetic fields, such as those from mobile phones, alter regional cerebral blood flow and sleep and waking EEG.
Exposed system:
  • human
  • partial body: head (left side)

Methods Endpoint/measurement parameters/methodology

Investigated material:
Time of investigation:
  • before exposure
  • during exposure

Main outcome of study (acc. to author)

The data showed that headache was more commonly reported after exposure than sham exposure, mainly due to an increase in the non-symptom group (control group).
Neither group could detect radiofrequency exposure better than by chance.
A belief that the radiofrequency irradiation had been active was associated with skin symptoms.
Further investigation of the higher prevalence of headache in the non-symptom group and a possible physiological correlation should be performed.
The findings indicate a need to better characterize subjects in cell phone exposure studies and differences between symptom and non-symptom groups.
Study character:

Study funded by

  • Mobile Manufacturers Forum (MMF), Belgium

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