研究のタイプ: 医学／生物学の研究 (experimental study)

[B6C3F1マウスをGSM/ DCS高周波放射線に1週間および6週間ばく露させたときの小核形成への影響] med./bio.

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

著者: Gorlitz BD, Muller M, Ebert S, Hecker H, Kuster N, Dasenbrock C
掲載誌: Radiat Res 2005; 164 (4) Pt 1: 431-439
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この研究は、1週間あるいは6週間のばく露期間で、1日2時間、無線周波（RF）電磁界のばく露を受けたマウスの末梢血および骨髄の赤血球、ならびにケラチノサイトおよび脾臓リンパ球における小核誘導の変化を調べた。実験に用いた電磁界は、GSM900およびDCS1800ハンドセットからのばく露をシミュレートしたものであり、通話（GSM Basic）、リスニング（DTX）および環境中の移動（ハンドオーバー、出力制御）において生じる低周波振幅変調成分が含まれた。搬送周波数は、システムのアップリンク帯域の中心、つまりGSMの場合は902 MHz、DCSの場合は1747 MHzに設定した。一様な全身ばく露を与えるように、ばく露セットアップに固定された円筒管内にマウスを拘束した。スロット平均全身SARは、1週間ばく露実験においては33.2、11.0、3.7および0 mW / g、6週間ばく露実験においては24.9、8.3、2.8および0 mW / gに調整された。このようなばく露レベルは、遺伝毒性のエンドポイントに影響を与える可能性のある熱的影響を持たないことを事前テストで確認した上で決定された。大腿骨の骨髄細胞（1週間ばく露実験）、末梢血の赤血球（6週間ばく露実験）、尾根部ケラチノサイトおよび脾臓のリンパ球（両方の実験）をそれぞれ、動物から単離、染色して小核の分析を行なった。その結果、どちらのばく露期間でも、またどちらの周波数においても、動物に臨床学的な異常は検出されなかった；RF電磁界ばく露は赤血球の形成に影響を及ぼさなかった；1週間ばく露後の多色性赤血球の正常色性赤血球に対する比率は、擬似ばく露群と差がなかった；RF電磁界ばく露群の骨髄または末梢血の赤血球、ケラチン産生細胞、または脾臓リンパ球での小核の発生数は、擬似ばく露群のものに比べ上昇しなかった、と報告している。

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研究目的（著者による）

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.

詳細情報

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.

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 902–1,747 MHz
Modulation type: pulsed
ばく露時間: 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))
ばく露2: 902–1,747 MHz
Modulation type: pulsed
ばく露時間: 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))

ばく露1

主たる特性
周波数 902–1,747 MHz
タイプ
  • electromagnetic field
特性
  • guided field
ばく露時間 repeated daily exposure, 2 h/day, for 5 days
Additional information Exposure was performed with a 902 MHz or a 1747 MHz GSM signal.
Modulation
Modulation type pulsed
Additional information

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].
ばく露装置
ばく露の発生源／構造
チャンバの詳細 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].
ばく露装置の詳細 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 information 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.
パラメータ
測定量 値 種別 Method Mass 備考
SAR 33.2 mW/g average over mass 測定値および計算値 whole body maximum slot average high dose exposure
SAR 4 mW/g average over mass 測定値および計算値 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 測定値および計算値 whole body maximum slot average medium dose exposure
SAR 1.33 mW/g average over mass 測定値および計算値 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 測定値および計算値 whole body maximum slot average low dose exposure
SAR 0.44 mW/g average over mass 測定値および計算値 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).

測定および計算の詳細

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.

ばく露2

主たる特性
周波数 902–1,747 MHz
タイプ
  • electromagnetic field
特性
  • guided field
ばく露時間 repeated daily exposure, 2 h/day, 5 days/week, for 6 weeks
Additional information Exposure was performed with a 902 MHz or a 1747 MHz GSM signal.
Modulation
Modulation type pulsed
Additional information

same as E1
ばく露装置
ばく露の発生源／構造
  • E1と同じ装置
Sham exposure A sham exposure was conducted.
パラメータ
測定量 値 種別 Method Mass 備考
SAR 24.9 mW/g average over mass 測定値および計算値 whole body maximum slot average high dose exposure
SAR 3 mW/g average over mass 測定値および計算値 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 測定値および計算値 whole body maximum slot average medium dose exposure
SAR 1 mW/g average over mass 測定値および計算値 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 測定値および計算値 whole body maximum slot average low dose exposure
SAR 0.33 mW/g average over mass 測定値および計算値 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): [900 MHzでの動物実験で正確に全身平均SARを決定するための効率的なRFばく露装置]
  • Wiart J et al. (2000): [GSM 携帯電話での無線周波ばく露に対する電源制御と不連続な通信の影響分析]

ばく露を受けた生物:

方法 影響評価項目／測定パラメータ／方法

研究対象とした生物試料:
調査の時期:
  • ばく露前
  • ばく露中
  • ばく露後

研究の主なアウトカム（著者による）

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.

研究の種別:

研究助成

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