Study type: Medical/biological study (experimental study)

Effects of 1-week and 6-week exposure to GSM/DCS radiofrequency radiation on micronucleus formation in B6C3F1 mice med./bio.

By: Gorlitz BD, Muller M, Ebert S, Hecker H, Kuster N, Dasenbrock C
Published in: Radiat Res 2005; 164 (4) Pt 1: 431-439
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Aim of study (acc. to author)

To study the possible induction of micronuclei in erythrocytes of the peripheral blood and bone marrow from the femur and in keratinocytes from the tail root and spleen lymphocytes of mice exposed to radiofrequency irradiation for 2 h per day over periods of 1 and 6 weeks, respectively.

Background/further details

In the one-week study, immature polychromatic erythrocytes from bone marrow were used; in the 6-week study, mature normochromatic erythrocytes from the peripheral blood were used.
In the one week study, a seperate group of mice were treated with cyclophosphamide (30 mg/kg) and used as positive control.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 902–1,747 MHz
Modulation type: pulsed
Exposure duration: repeated daily exposure, 2 h/day, for 5 days
  • SAR: 33.2 mW/g average over mass (whole body) (maximum slot average high dose exposure)
  • SAR: 4 mW/g average over mass (whole body) (average high dose exposure phase I (phase II: 2.8 mW/g and phase III: 1.04 mW/g))
  • SAR: 11.1 mW/g average over mass (whole body) (maximum slot average medium dose exposure)
  • SAR: 1.33 mW/g average over mass (whole body) (average medium dose exposure phase I (phase II: 0.93 mW/g and phase III: 0.35 mW/g))
  • SAR: 3.7 mW/g average over mass (whole body) (maximum slot average low dose exposure)
  • SAR: 0.44 mW/g average over mass (whole body) (average low dose exposure phase I (phase II: 0.31 mW/g and phase III: 0.114 mW/g))
Exposure 2: 902–1,747 MHz
Modulation type: pulsed
Exposure duration: repeated daily exposure, 2 h/day, 5 days/week, for 6 weeks
  • SAR: 24.9 mW/g average over mass (whole body) (maximum slot average high dose exposure)
  • SAR: 3 mW/g average over mass (whole body) (average high dose exposure phase I (phase II: 2.1 mW/g and phase III: 0.78 mW/g))
  • SAR: 8.2 mW/g average over mass (whole body) (maximum slot average medium dose exposure)
  • SAR: 1 mW/g average over mass (whole body) (average medium dose exposure phase I (phase II: 0.7 mW/g and phase III: 0.26 mW/g))
  • SAR: 2.7 mW/g average over mass (whole body) (maximum slot average low dose exposure)
  • SAR: 0.33 mW/g average over mass (whole body) (average low dose exposure phase I (phase II: 0.23 mW/g and phase III: 0.086 mW/g))

Exposure 1

Main characteristics
Frequency 902–1,747 MHz
Type
Charakteristic
  • guided field
Exposure duration repeated daily exposure, 2 h/day, for 5 days
Additional info Exposure was performed with a 902 MHz or a 1747 MHz GSM signal.
Modulation
Modulation type pulsed
Additional info

The exposure signal applied consisted of three phases, each lasting 40 min: GSM Basic, GSM Talk consisting of random changes between the non-DTX (2/3) and DTX (1/3) modes, and GSM "Environment" including GSM features such as non-DTX, DTX, power control, and handovers according to their statistical occurrence based on data presented in [Wiart et al., 2000].
Exposure setup
Exposure source
Chamber Two exposure systems were used for the experiments: one for exposure with a 902 MHz GSM signal and one for exposure with a 1747 MHz DCS signal. The exposure systems were located in separate animal rooms. The exposure system consisted of a signal generation, control and monitoring unit and four identical cylindrically shaped exposure units (wheels), each enabling exposure of up to 65 animals. The exposure unit was an adaptation of the Ferris-wheel concept used in [Balzano et al., 2000].
Setup Each wheel consisted of two parallel circular stainless steel metal plates with a distance of 11.7 cm that were connected around the edges by parallel metal bars functioning as a shortcut to make the setup structure resonant. Either a conical antenna (902 MHz) or a bi-conical antenna (1747 MHz) was placed in the centre between the plates. In the 902 MHz setups, high-permittivity plastic bricks were also inserted between neighbouring tubes to increase the electrical distance and therefore suppress distortion from neighbouring animals. Encased between the plates were 65 tapered cylindrical polycarbonate tubes (i.d. 40 mm) arranged radially around the antenna. Each wheel housed 20 animals; all other positions were filled with mouse dummies of the same weight consisting of a conical plastic tube filled with a liquid with the same dielectrical parameters as muscle tissue.
Sham exposure A sham exposure was conducted.
Additional info Each exposure unit was adjusted to a different exposure level, resulting in four dose levels (high, medium, low and sham). The exposure levels for the 1- and 6-week studies were determined in a pre-test to confirm that no thermal effects occurred. In the 6-week study, exposure levels were slightly reduced, so that the high dose level was close to but below the thermal threshold. In the 1-week study, a separate group of rats was treated orally with cyclophosphamide as positive control.
Parameters
Measurand Value Type Method Mass Remarks
SAR 33.2 mW/g average over mass measured and calculated whole body maximum slot average high dose exposure
SAR 4 mW/g average over mass measured and calculated whole body average high dose exposure phase I (phase II: 2.8 mW/g and phase III: 1.04 mW/g)
SAR 11.1 mW/g average over mass measured and calculated whole body maximum slot average medium dose exposure
SAR 1.33 mW/g average over mass measured and calculated whole body average medium dose exposure phase I (phase II: 0.93 mW/g and phase III: 0.35 mW/g)
SAR 3.7 mW/g average over mass measured and calculated whole body maximum slot average low dose exposure
SAR 0.44 mW/g average over mass measured and calculated whole body average low dose exposure phase I (phase II: 0.31 mW/g and phase III: 0.114 mW/g)
Additional parameter details

The maximum slot-averaged whole-body exposure (peak SAR level) was the same for all three phases; however, the resulting average SAR level varied: 100% (GSM Basic), 70% (GSM Talk) and 26% (GSM Environment).

Measurement and calculation details

During the entire experiment, exposure levels were controlled and monitored with two field sensors inside each wheel. Exposure levels were automatically adjusted if any drift/change occurred, ensuring stable exposure conditions inside the setup.

Exposure 2

Main characteristics
Frequency 902–1,747 MHz
Type
Charakteristic
  • guided field
Exposure duration repeated daily exposure, 2 h/day, 5 days/week, for 6 weeks
Additional info Exposure was performed with a 902 MHz or a 1747 MHz GSM signal.
Modulation
Modulation type pulsed
Additional info

same as E1
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 24.9 mW/g average over mass measured and calculated whole body maximum slot average high dose exposure
SAR 3 mW/g average over mass measured and calculated whole body average high dose exposure phase I (phase II: 2.1 mW/g and phase III: 0.78 mW/g)
SAR 8.2 mW/g average over mass measured and calculated whole body maximum slot average medium dose exposure
SAR 1 mW/g average over mass measured and calculated whole body average medium dose exposure phase I (phase II: 0.7 mW/g and phase III: 0.26 mW/g)
SAR 2.7 mW/g average over mass measured and calculated whole body maximum slot average low dose exposure
SAR 0.33 mW/g average over mass measured and calculated whole body average low dose exposure phase I (phase II: 0.23 mW/g and phase III: 0.086 mW/g)
Additional parameter details

The maximum slot-averaged whole-body exposure (peak SAR level) was the same for all three phases; however, the resulting average SAR level varied: 100% (GSM Basic), 70% (GSM Talk) and 26% (GSM Environment).

Reference articles

  • Balzano Q et al. (2000): An efficient RF exposure system with precise whole-body average SAR determination for in vivo animal studies at 900 MHz
  • 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:
Time of investigation:
  • before exposure
  • during exposure
  • after exposure

Main outcome of study (acc. to author)

The radiofrequency field exposure had no influence on the formation of red blood cells. After 1 week of exposure, the ratio of polychromatic to normochromatic erythrocytes was unchanged in the exposed groups compared to the sham-exposed groups.
Furthermore, the radiofrequency field exposure did not induce an increase in the number of micronuclei in erythrocytes of the bone marrow or peripheral blood, in keratinocytes, or in spleen lymphocytes compared to the sham-exposed control.

Study character:

Study funded by

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