Study type: Medical/biological study (experimental study)

GSM and DCS Wireless Communication Signals: Combined Chronic Toxicity/Carcinogenicity Study in the Wistar Rat med./bio.

By: Smith P, Kuster N, Ebert S, Chevalier HJ
Published in: Radiat Res 2007; 168 (4): 480-492
Download citation in RIS format

Aim of study (acc. to editor)

To study the effects of GSM and DCS wireless communication signals on carcinogenicity in rats.

Background/further details

A total of 1200 rats were used. Groups of 65 male and 65 female rats were exposed to GSM and DCS signals at three different SAR values (4 W/kg, 1.33 W/kg, 0.44 W/kg). In addition, there was a sham exposed group for each signal type. An additional group of 65 males and 65 females was kept unexposed and unrestrained and served as the cage control.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 902 MHz
Modulation type: pulsed
Exposure duration: repeated daily exposure, 2 h/day, 5 days/week, for 52 or 104 weeks
  • SAR: 3.7 W/kg average over time (whole body)
  • SAR: 1.23 W/kg average over time (whole body)
  • SAR: 0.41 W/kg average over time (whole body)
Exposure 2: 1,747 MHz
Modulation type: pulsed
Exposure duration: repeated daily exposure, 2 h/day, 5 days/week, for 52 or 104 weeks
  • SAR: 4 W/kg average over time (whole body)
  • SAR: 1.33 W/kg average over time (whole body)
  • SAR: 0.44 W/kg average over time (whole body)

General information

The GSM and DCS experiments were conducted in adjacent rooms, each having 16 exposure units installed. A placement rotation scheme was applied to all rats in order to minimize dose differences due to signal differences within and between exposure units.

Exposure 1

Main characteristics
Frequency 902 MHz
Type
Charakteristic
  • guided field
Exposure duration repeated daily exposure, 2 h/day, 5 days/week, for 52 or 104 weeks
Modulation
Modulation type pulsed
Additional info

GSM signal
Exposure setup
Exposure source
Chamber The exposure unit for up to 17 animals consisted of a circular cascade of 17 electromagnetically isolated and resonant waveguides (terminated by stainless steel wires), all excited by one quarter-loop antenna placed in the center and providing uniform circular excitation (maximum deviation of isotropy of ±0.2 dB).
Setup Rats were individually restrained in horizontal position in metal-free polycarbonate tubes and were positioned in optimal H-polarization with their centers of mass at 150 ± 2 mm from the shortcut thus providing a reasonably homogeneous exposure for varying sizes. Missing animals were replaced with a dummy (container simulating the absorption characteristics) to minimise imbalances of the excitations.
Sham exposure A sham exposure was conducted.
Additional info The RF signals were generated by a digital GSM/DCS signal generator combined with a frame generator and control unit [Kainz et al., 2006]. Each slot was modulated with a random code.
Parameters
Measurand Value Type Method Mass Remarks
SAR 3.7 W/kg average over time measured and calculated whole body -
SAR 1.23 W/kg average over time measured and calculated whole body -
SAR 0.41 W/kg average over time measured and calculated whole body -
Additional parameter details

Each exposure session was divided into three phases of 40 min: (1) GSM Basic (non-DTX) mode with one slot active per basic frame and each 26th basic frame idle. (2) GSM Talk mode consisting of temporal changes between the non-DTX (average 10.8 s) and DTX (average 5.6 s) modes. (3) GSM Environment mode consisting of a GSM Talk signal further amplitude-modulated by a power control function statistically based on measurements performed by France Telecom [Wiart et al., 2000]. The peak (slot-averaged) SAR level for all three phases was the same, however, the resulting average SARs varied: 100% (GSM Basic), 70% (GSM Talk), and 26% (GSM Environment). The SAR values indicated above are those for GSM Basic. The SAR levels in the GSM study had to be decreased in three steps over time since the body weight increase of the rats was greater than predicted and the available power was insufficient to maintain 4 W/kg. So, the SAR (GSM Basic) averaged over the entire exposure period was only 3.7 W/kg for the high-dose group. The SAR values for the medium- and low-dose groups were also adjusted accordingly to keep the target ratio of three between the dose groups.

Measurement and calculation details

During exposure, the electric field strength inside the waveguide cavity was monitored and controlled almost continuously at two different places. A new methodology was used to obtain comprehensive dosimetric information for whole-body and peak spatial SAR as well as the averaged values for the most important organs including the uncertainty as well as the instant and life-long variations [Kuster et al., 2006].

Exposure 2

Main characteristics
Frequency 1,747 MHz
Type
Charakteristic
  • guided field
Exposure duration repeated daily exposure, 2 h/day, 5 days/week, for 52 or 104 weeks
Modulation
Modulation type pulsed
Additional info

DCS signal
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 4 W/kg average over time measured and calculated whole body -
SAR 1.33 W/kg average over time measured and calculated whole body -
SAR 0.44 W/kg average over time measured and calculated whole body -
Additional parameter details

The peak (slot-averaged) SAR level for all three phases was the same (33.2 W/kg for the high-dose group), however, the resulting average SARs varied: 100% (GSM Basic), 70% (GSM Talk), and 26% (GSM Environment). The SAR values indicated above are those for GSM Basic.

Reference articles

  • Kainz W et al. (2006): Development of novel whole-body exposure setups for rats providing high efficiency, National Toxicology Program (NTP) compatibility and well-characterized exposure
  • Kuster N et al. (2006): Methodology of detailed dosimetry and treatment of uncertainty and variations for in vivo studies
  • Wiart J et al. (2000): Analysis of the influence of the power control and discontinuous transmission on RF exposure with GSM mobile phones

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Investigated organ system:
Time of investigation:
  • during exposure
  • after exposure

Main outcome of study (acc. to author)

The study produced no evidence that radiofrequency electromagnetic field exposure under these conditions had any effect on the incidence or severity of any non-neoplastic condition or the type, incidence, multiplicity and latency of any neoplastic lesion.

Study character:

Study funded by

Related articles