Study type: Medical/biological study (experimental study)

Two-year chronic bioassay study of rats exposed to a 1.6 GHz radiofrequency signal. med./bio.

Published in: Radiat Res 2004; 162 (2): 201-210

Aim of study (acc. to author)

To determine whether long-term exposure to a 1.6 GHz radiofrequency field would affect the incidence of cancer in rats. Whole-body far field exposures of pregnant rats were initiated at 19 days of gestation and continued for dams and pups after parturition until weaning (approximately 23 days old). The offspring of these dams were selected for near field treatment (divided in male and female groups). Near field exposures were initiated when the offspring were 36 +/- 1 days old and continued until the rats were 2 years old.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 1.62 GHz
Exposure duration: repeated daily exposure, 2 h/day, for about 27 days
Exposure 2: 1.62 GHz
Exposure duration: repeated daily exposure, 2 h/day, 5 days/week, from 35 days up to about 2 years of age

Exposure 1

Main characteristics
Frequency 1.62 GHz
Type
Charakteristic
Exposure duration repeated daily exposure, 2 h/day, for about 27 days
Modulation
Modulation type cf. additional info
Additional info

Iridium signal with differentially encoded quaternary phase shift keying (DEQPSK) and a frame length of 90 ms with 11 data slots per frame

Exposure setup
Exposure source
Distance between exposed object and exposure source 3 m
Chamber The exposure setup used a horizontal beam orientation in a flared plate design [Wilson et al., 2002]. The parallel-plate enclosure (2.48 m long) was lined with copper foil on top and bottom plates, and the sides were covered with pyramidal anechoic material. It was excited by a coaxial to waveguide adapter and provided for RF exposure (23 dB beam width) at the position of the animal cages in an area of 2.11 x 1.11 m at 3 to 3.5 m (approx. 12 λ) from the antenna, with a uniformity of better than 62.6 dB.
Setup Eighteen standard rat cages (45.7 x 24.1 x 20.3 cm) containing single rats with their offspring were located in a box (1.45 x 2.40 x 1.60 m) covered on five of the interior walls with pyramidal or grooved anechoic material. The cages were arranged in three rows of six cages with their front surfaces in the plane of the parallel plate aperture. The sham system was installed in an adjoining room.
Sham exposure A sham exposure was conducted.
Additional info Whole-body far-field exposures were initiated at 19 days of gestation and continued for dams and pups after parturition until weaning at about 23 days of age. The animal groups were not exposed in a blinded fashion.
Parameters
Measurand Value Type Method Mass Remarks
power density 0.33 mW/cm² mean measured - -
SAR 0.16 W/kg mean calculated brain 0.10-0.22 W/kg
SAR 0.06 W/kg mean calculated whole body 0.036-0.077 W/kg

Exposure 2

Main characteristics
Frequency 1.62 GHz
Type
Charakteristic
Exposure duration repeated daily exposure, 2 h/day, 5 days/week, from 35 days up to about 2 years of age
Modulation
Modulation type cf. additional info
Additional info

Iridium signal with differentially encoded quaternary phase shift keying (DEQPSK) and a frame length of 90 ms with 11 data slots per frame

Exposure setup
Exposure source
Chamber The exposure facility contained nine partially shielded double units each housing two near-field exposure carousels that were similar to those described by Moros et al. [1998]. RF absorbing material was placed around each exposure unit.
Setup Ten animals per carousel were placed with their head first in cylindrical tubes arranged radially around a central antenna.
Sham exposure A sham exposure was conducted.
Additional info Six of the units were assigned to each of the three exposure conditions that were rotated every six weeks among the three zones. The animal groups were coded after far-field exposure so that near-field exposure and sham exposure were truly blind.
Parameters
Measurand Value Type Method Mass Remarks
SAR 0.16 W/kg mean calculated brain -
SAR 1.6 W/kg mean calculated brain -

Reference articles

  • Schönborn F et al. (2004): Dosimetric analysis of the carousel setup for the exposure of rats at 1.62 GHz.
  • Wilson BW et al. (2002): Space efficient system for small animal, whole body microwave exposure at 1.6 GHz.
  • Adey WR et al. (1999): Spontaneous and nitrosourea-induced primary tumors of the central nervous system in Fischer 344 rats chronically exposed to 836 MHz modulated microwaves.
  • Moros EG et al. (1998): A compact shielded exposure system for the simultaneous long-term UHF irradiation of forty small mammals: I. Electromagnetic and environmental design.

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)

No statistically significant differences were revealed among treatment groups for number of live pups/litter, survival rate, and weaning weights, nor were there differences in clinical signs or neoplastic lesions. The percentages of rats surviving at the end of the near field irradiation were not different among the male groups. In the female groups a significant decrease in survival time was found for the cage control group.

Study character:

Study funded by

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