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

[B6C3F1マウスにおけるGSMおよびDCS無線通信信号の発がん性研究] med./bio.

Carcinogenicity study of GSM and DCS wireless communication signals in B6C3F1 mice

著者: Tillmann T, Ernst H, Ebert S, Kuster N, Behnke W, Rittinghausen S, Dasenbrock C
掲載誌: Bioelectromagnetics 2007; 28 (3): 173-187
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【目的】移動通信グローバルシステム(GSM)とデジタルパーソナル通信システム(DCS)の送受話器からの無線周波数放射(RFR)にばく露したマウスにおける発がん影響の可能性を検出し評価すること。【方法】合計1170匹のB6C3F1マウスを用いた。放射は、通信用帯域の中心である902MHz(GSM)と1747MHz(DCS)で動作する送受話器で行われた。拘束されたマウスに対し、3つの全身平均比吸収率(SAR)レベル、0.4、1.3、4.0mW/g bwのばく露および擬似ばく露を、2年間にわたり、1週間に5日、1日に2時間行った。【結果】フィッシャーの対比較検定によれば、臓器関連腫瘍の発生率に関しては、RFばく露グループにおけるどのようなタイプの腫瘍発生率も擬似ばく露グループと比較して著しい増加を示さなかった。興味深いことに、肝細胞がんの発生率はEMFばく露グループと擬似ばく露グループで同様であったが、一方、両実験において、オスの肝腺腫の発生率はばく露レベルが増加するとともに減少した；高ばく露グループにおける発生率は、擬似ばく露グループの発生率と統計的に有意な差異があった。無処置マウスでの発がん率を公知の発がん率と比べると、観察された発がん率は歴史的標準データの範囲内であることが明らかになった。【結論】オスとメスのB6C3F1マウスを無線GSMとDCS周波数信号に4.0W/kgまでの全身比吸収率でばく露させることが、健康への悪影響を生じる、または、腫瘍性および非腫瘍性の背景病変の発生率または重症度に対して蓄積的影響をもつことを示すいかなる証拠も示されなかった。以上から、RFは発がんの可能性をもつという如何なる証拠も提供しなかった。

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研究目的（著者による）

The purpose of this in vivo study was to evaluate possible carcinogenic effects in mice exposed to 900 MHz (GSM) and 1747 MHz (DCS) radiofrequency irradiation.

詳細情報

A total of 1170 mice were exposed over a period of two years to three different whole body average specific absorption rates (SAR).

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, 5 days/week, for 2 years
  • SAR: 33.2 mW/g peak (whole body)
  • SAR: 4 mW/g average over time (whole body) (phase II: 2.8 mW/g and phase III: 1.0 mW/g)
  • SAR: 11.1 mW/g peak (whole body)
  • SAR: 1.3 mW/g average over time (whole body) (phase II: 0.93 mW/g and phase III: 0.35 mW/g)
  • SAR: 3.7 mW/g peak (whole body)
  • SAR: 0.4 mW/g average over time (whole body) (phase II: 0.35 mW/g and phase III: 0.11 mW/g)

ばく露1

主たる特性
周波数 902–1,747 MHz
タイプ
  • electromagnetic field
ばく露時間 repeated daily exposure, 2 h/day, 5 days/week, for 2 years
Additional information Exposure was performed with a 902 MHz GSM or a 1747 MHz DCS signal. Reference article: Ebert S, Berdinas Torres V, Frohlich J, Kuster N. 2006. SAR uniformity in Ferris wheel setups used in RF exposure of mice at 900 MHz. (In preparation).
Modulation
Modulation type pulsed
Pulse width 0.57 ms
Duty cycle 12.5 %
Additional information

The exposure signal applied consisted of three phases, each lasting 40 min: GSM Basic (non-DTX), GSM Talk consisting of random changes between the non-DTX (2/3) and DTX (1/3) modes, and GSM Environment consisting of a GSM Talk signal further amplitude-modulated by a statistically calculated power control function, based on data presented by Wiart et al. [2001, publication 12955]. Each timeslot was modulated with a standard random code.
ばく露装置
ばく露の発生源／構造
チャンバの詳細 Two exposure systems, one for each frequency, were located in separate rooms. Each system consisted of a signal generation unit, control and monitoring unit, and four "Ferris wheel" exposure units, one for each dose level (high, medium, low, and sham). The "Ferris wheel" concept developed by Balzano et al. [2000, publication 7306] was adopted and optimized for this study.
ばく露装置の詳細 Each wheel, enabling exposure of up to 65 animals, consisted of two parallel, circular, stainless steel metal plates, 117 mm apart, with a conical (GSM) or bi-conical (DCS) antenna in their center, and stainless steel poles forming a short-cut of the cylindrical cavity at a radius of 755 mm. The animals, restrained in tubes similar to those used and approved for inhalation studies, were positioned at a radius (center of wheel to center of tubes) of 700 mm for GSM and 670 mm for DCS. In order to maintain a symmetrical load, missing animals were replaced by conical plastic tubes filled with 36 ml of liquid simulating the dielectrical parameters of muscle tissue. Higher modes were reduced by dielectric bricks between the animals at 902 MHz. Details of the setup and dosimetry are provided in Ebert et al. [2006] (in preparation).
Sham exposure A sham exposure was conducted.
Additional information Male or female mice were each randomized by weight into 9 treatment groups: 2 x 4 RF dose groups (incl. sham) and one untreated cage control group. Loading and unloading of the exposure wheel was done first in/first out resulting in an additional restraint time of up to 32 min for each mouse. The study was performed blind to all scientists involved.
パラメータ
測定量 値 種別 Method Mass 備考
SAR 33.2 mW/g peak 測定値および計算値 whole body -
SAR 4 mW/g average over time 測定値および計算値 whole body phase II: 2.8 mW/g and phase III: 1.0 mW/g
SAR 11.1 mW/g peak 測定値および計算値 whole body -
SAR 1.3 mW/g average over time 測定値および計算値 whole body phase II: 0.93 mW/g and phase III: 0.35 mW/g
SAR 3.7 mW/g peak 測定値および計算値 whole body -
SAR 0.4 mW/g average over time 測定値および計算値 whole body phase II: 0.35 mW/g and phase III: 0.11 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). These values have been averaged over 2 years.

測定および計算の詳細

The incident field was adjusted according to a numerically determined dose-weight function in order to maintain the same exposure independent of the animal's weight/age. Exposure levels were monitored and automatically controlled using two electric field sensors inside each wheel. The dosimetry provided information about whole body, organ and peak spatial average SARs as well as about uncertainty and instant and lifetime variations. Values assessed using the methodology of Kuster et al. [2006, publication 13770] are presented in two tables. The whole-body exposure as well as the specific organ SARs were several magnitudes larger than those of humans during phone or base station exposure. Several pre-tests showed that the high dose level was close to, yet below, the thermal threshold. [Ebert et al., 2005, publication 12740].

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:
研究対象とした臓器系:
調査の時期:
  • ばく露中
  • ばく露後

研究の主なアウトカム（著者による）

There was no significant increase in the organ-related tumor incidence of any particular tumor type in the radio frequency exposed groups.

研究の種別:

研究助成

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