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

[インビトロでのヒトリンパ球におけるX線誘発染色体異常に対する携帯電話周波数の変調マイクロ波の影響] med./bio.

Effects of modulated microwave radiation at cellular telephone frequency (1.95 GHz) on X-ray-induced chromosome aberrations in human lymphocytes in vitro

著者: Manti L, Braselmann H, Calabrese ML, Massa R, Pugliese M, Scampoli P, Sicignano G, Grossi G
掲載誌: Radiat Res 2008; 169 (5): 575-583
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この研究は、細胞毒性が既知であるX線のばく露を与えた後の修復効率に対するUMTS電磁界の影響を調べた。以前に特性評価した導波管システムを用いてヒト末梢血リンパ球にSARが０．５と２．０W/kgのUMTS信号を24時間与えた。実験には4群：RFばく露（または擬似ばく露）の直前に４GyX線照射をした群としない群、を用いた。染色体異常の頻度は、染色体の中期延展体( metaphase spreads) について蛍光in situ ハイブリダイゼーションにより計測した。この結果、異常細胞のの割合はUTMSばく露により大きく違わなかった：細胞ごとの交換頻度はSAR2.0 W/kgの場合、小さな、しかし統計学的に有意な増加を示した、などの所見を報告し、RFはX線誘発DNA損傷の修復に影響を与え、細胞死の経路を変化させるかも知れないと結論している。

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研究目的（著者による）

This in vitro study was conducted to study the influence of 1.95 GHz UMTS modulated radio frequency exposure on X ray induced chromosome aberrations in human lymphocytes.

詳細情報

The lymphocytes were obtained from four healthy male donors aged between 23 and 30 years.

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 1.95 GHz
ばく露時間: continuous for 24 h
  • SAR: 2 W/kg mean
  • SAR: 0.5 W/kg mean

ばく露1

主たる特性
周波数 1.95 GHz
タイプ
  • electromagnetic field
特性
  • guided field
ばく露時間 continuous for 24 h
Modulation
Modulation type cf. additional information
Additional information

UMTS signal meeting the WCDMA standard, according to the 3GPP 3.5 2001-03 specifications (five power-controlled user data channels and one control channel)
ばく露装置
ばく露の発生源／構造
  • 導波管
  • WR 430, rectangular, 109.2 mm x 54.6 mm
チャンバの詳細 The standardized exposure device has been described in [Sannino et al., 2006 and Calabrese et al., 2006]. Two identical waveguides, one for RF and one for sham exposure, were housed in a commercial incubator at 37°C with 95% air and 5% CO2.
ばく露装置の詳細 A total of eight 35-mm Petri dishes were inoculated with lymphocytes from each donor. Four dishes, each filled with 3 ml of cell suspension, were held by a plastic stand in each waveguide. The distance between the samples allowed simultaneous exposure at two different SARs. The induced electric field was essentially parallel to the sample surface.
Sham exposure A sham exposure was conducted.
Additional information The feeding end was a coaxial waveguide adapter, the other end terminated with a fixed short circuit. The center of the samples was at a distance of 0.5 λ from the short circuit in order to achieve the best trade-off between efficiency and SAR uniformity.
パラメータ
測定量 値 種別 Method Mass 備考
SAR 2 W/kg mean 電力損失による決定値 - -
SAR 0.5 W/kg mean 電力損失による決定値 - -
Additional parameter details

Two of the dishes in each waveguide were given 4 Gy of X rays immediately before RF or sham exposure (one dish per SAR). The X rays were produced by a Thomson tube (250 kVp, 0.8 Gy/min) and filtered by 1-mm thick copper foil.

測定および計算の詳細

Incident and reflected powers were measured using a bidirectional power sensor connected to a computer continuously adjusting the power level of the signal generator to the required SAR. Measurements of local SAR and power efficiency showed good agreement with the calculated values. The ratio between the SAR standard deviation and the average SAR was 0.33 in all four samples. The measured increase in temperature during the RF exposure at 2 W/kg was 0.2 ± 0.1°C, which was considered sufficiently low to exclude damage induced by thermal processes.

Reference articles

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:
  • ばく露後

研究の主なアウトカム（著者による）

The UMTS exposure did not cause differences in the fraction of X-ray-induced aberrant cells. However, a small but statistically significant increase in the frequency of X-ray-induced chromosome exchanges per cell, especially at the specific absorption rate of 2 W/kg was observed.
In conclusion, although the 1.95 GHz UMTS modulated radiofrequency field does not exacerbate the yield of aberrant cells caused by ionizing radiation, the overall burden of X-ray-induced chromosomal damage per cell in first-mitosis lymphocytes may be enhanced at 2.0 W/kg SAR.

研究の種別:

研究助成

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