Study type: Medical/biological study (experimental study)

Study on potential effects of "902-MHz GSM-type Wireless Communication Signals" on DMBA-induced mammary tumours in Sprague-Dawley rats med./bio.

By: Hruby R, Neubauer G, Kuster N, Frauscher M
Published in: Mutat Res Genet Toxicol Environ Mutagen 2008; 649 (1-2): 34-44
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Aim of study (acc. to author)

The aim of the study was to detect whether long-term exposure to 902 MHz GSM like modulated electromagnetic field affects DMBA-induced mammary tumors in female rats.

Background/further details

Five hundred female rats were each given a single oral dose of DMBA (17 mg per kg body weight) at an age of 46-48 days to induce mammary tumors. Three groups of 100 animals each were exposed from the next day onwards to three different specific absorption rates of 0.4 (low-dose group), 1.3 (mid-dose group) or 4.0 W/kg (high-dose group) for 6 months. A sham-exposed and a cage control group were performed as well.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 902 MHz
Modulation type: pulsed
Exposure duration: repeated daily exposure, 4 h/day, 5 days/week, for 6 months
  • SAR: 0.4 W/kg average over time (whole body)
  • SAR: 1.3 W/kg average over time (whole body)
  • SAR: 4 W/kg average over time (whole body)

Exposure 1

Main characteristics
Frequency 902 MHz
Type
Charakteristic
  • guided field
Exposure duration repeated daily exposure, 4 h/day, 5 days/week, for 6 months
Modulation
Modulation type pulsed
Pulse width 0.57 ms
Duty cycle 12.5 %
Repetition frequency 217 Hz
Additional info

GSM signal structure without the 26th slot being idle
Exposure setup
Exposure source
Chamber The exposure system [Kainz et al., 2006] consisted of 12 wheels, i.e., 3 per dose group. Each wheel consisted of a circular cascade of 17 sectored waveguides excited by one central quarter-loop antenna.
Setup Animals were restrained in a horizontal position in polycarbonate tubes (230 mm long, inner diameter max. 63 mm, tapering to 22 mm at the cone-shaped apex), identical to those used in inhalation studies, but without any metal.
Sham exposure A sham exposure was conducted.
Additional info The setup provided uniform SAR distribution and equal exposure for all animals in the same group. The position of each rat in the wheel was changed daily in a cyclic manner.
Parameters
Measurand Value Type Method Mass Remarks
SAR 0.4 W/kg average over time measured whole body -
SAR 1.3 W/kg average over time measured whole body -
SAR 4 W/kg average over time measured whole body -
Additional parameter details

The high dose was set close to but below the level causing a measurable body core-temperature increase [Ebert et al., 2005]. Ambient fields were found to be below 2 mV/m at RF (GSM) and below 50 V/m and 1.6 µT at power frequencies. From this, sham exposure was concluded to be far below 0.01 mW/kg.

Measurement and calculation details

The results of the detailed dosimetry conducted according to [Kuster et al., 2006] are given in a table, including both spatial peak and organ-averaged SAR values, as well as instant and lifetime variations and uncertainty values.

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
  • Ebert S et al. (2005): Response, thermal regulatory threshold and thermal breakdown threshold of restrained RF-exposed mice at 905 MHz

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

All radiofrequency exposed groups had, at different times, significantly more palpable mammary gland tumor masses compared to sham exposure. There were statistically significant more animals with malignant neoplasms in the low-dose and high-dose group. In addition, the highest number of adenocarcinoma was found in the low-dose group. The number of benign neoplasms was statistically significant lower in all radiofrequency exposure groups.
The cage control compared to sham exposure had statistically significant more palpable tumor masses, more benign and also more malignant neoplasms. Additionally, the cage control had in most aspects the highest incidence and malignancy of neoplasms among all groups.
In conclusion, the observed differences between the groups are not considered to give sufficient evidence for an effect of radiofrequency exposure on mammary tumor promotion or tumor progression.

Study character:

Study funded by

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