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

[連続波とGSM模擬波形を用いた1.8 W/kgでの１.8 GHzのばく露はシノラブディス・エレガンスのhsp16-1熱ショック遺伝子発現を誘導しない] med./bio.

Continuous wave and simulated GSM exposure at 1.8 W/kg and 1.8 GHz do not induce hsp16-1 heat-shock gene expression in Caenorhabditis elegans

著者: Dawe AS, Nylund R, Leszczynski D, Kuster N, Reader T, de Pomerai DI
掲載誌: Bioelectromagnetics 2008; 29 (2): 92-99
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【背景】線虫の一種（シノラブディス・エレガンス：生命科学研究の良いモデル動物。全ての遺伝子が解明されている。）の熱ショック蛋白（hsp16-1）のプロモータの導入遺伝子の発現がRFばく露により誘導されることが見られたが、これは微小な熱が原因かも知れないことを最近のデータは示している。しかし、この線虫研究で用いられたRF電磁界（SAR: 5-40 mW/ kg）はその他の研究で用いられたもの（SAR: 2 W/ kg）より遥かに低い。【目的と方法】この不一致を解明するため、同じ導入遺伝子に対し、より強度の高いRF電磁界ばく露（1.8 GHz; SARは最大 1.8 W/kg）を行った。【結果】連続波およびトークパルス波のRFばく露（ばく露時間2.5 時間、温度は25.8℃）において、擬似ばく露を上回る量のレポーター遺伝子発現は誘導されないことが示された。要するに、先行研究より高いRF電磁界強度（携帯電話送受話器からの最大許容ばく露レベルに近いもの）において誘導を試みても、この線虫の熱ショック蛋白遺伝子は上方調節されなかった。

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研究目的（著者による）

To study whether higher irradiation doses and/or pulse modulation can cause measurable heat-shock protein reporter gene induction in Caenorhabditis elegans (nematodes) in the absence of heating artefacts, transgenic worms were exposed to 1.8 GHz electromagnetic fields at SAR values of 1.8 W/kg for 2.5 h at 25°C.

詳細情報

The radiofrequency fields used in previous Caenorhabditis elegans studies were much weaker (see publication 4466, publication 4467, publication 6611, and publication 12968).

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 1.8 GHz
Modulation type: CW
ばく露時間: continuous for 2.5 h
ばく露2: 1.8 GHz
Modulation type: pulsed
ばく露時間: continuous for 2.5 h

General information

In total, seven CW runs and five Talk-pulsed runs were completed, each involving six exposed replicates compared against six sham replicates.

ばく露1

主たる特性
周波数 1.8 GHz
タイプ
  • electromagnetic field
特性
  • guided field
ばく露時間 continuous for 2.5 h
Modulation
Modulation type CW
ばく露装置
ばく露の発生源／構造
チャンバの詳細 The fully automated exposure system consisted of two identical chambers for RF or sham exposure, mounted in the same incubator, and enabled well-controlled exposures of cells in monolayers or in suspension [Schuderer et al., 2004].
ばく露装置の詳細 The Petri dishes were exposed in H-polarization. The induced E-fields had a pronounced polarization parallel to the bottom and in the direction of the waveguide axis. The induced H-fields were orthogonal to the induced E-fields, both of which were dominantly parallel to the bottom of the dish.
Sham exposure A sham exposure was conducted.
パラメータ
測定量 値 種別 Method Mass 備考
SAR 1.8 W/kg mean - - -
磁界強度 1.6 A/m - - - -
Additional parameter details

The ambient ELF exposure measured in several positions within the incubator was below 5 µT rms in the entire volume of the waveguide.

測定および計算の詳細

The system monitored incident electric field strengths, ventilator currents, outlet air temperatures and state of all equipment every 10 s. Previous dosimetry [Schuderer et al., 2004] had to be extended due to the larger dimensions of C. elegans compared to cells. The gradient in z-direction was about 4 W/kg/mm, which means that the bottoms of the worms were exposed to an SAR of about 2 W/kg and the tops to 1.6 W/kg. The non-uniformity within the bottom of the dish was 23%, and the relative variability between Petri dishes and experiments was estimated to be less than 5%.

ばく露2

主たる特性
周波数 1.8 GHz
タイプ
  • electromagnetic field
特性
  • guided field
ばく露時間 continuous for 2.5 h
Modulation
Modulation type pulsed
Additional information

GSM Talk signal characterized by a random change between the DTX and non-DTX or GSM Basic modes. The distribution in time was exponential with a mean duration of 10.8 s for non-DTX and 5.6 s for DTX. The dominant modulation components of this signal are 2, 8, 217, 1733 Hz, and higher harmonics [Tillmann et al., 2007].
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 1.8 W/kg mean - - -
磁界強度 1.6 A/m - - - -

Reference articles

  • Tillmann T et al. (2007): [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]
  • Schuderer J et al. (2004): [1800 MHzのインビトロ実験に用いる強力なばく露および環境制御機能を備えた高尖頭SARばく露装置]

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）

For both continuous wave and pulsed radiofrequency exposures, there was no indication that radiofrequency exposure could induce reporter gene expression above sham exposure levels. Thus, at much higher induced radiofrequency field strength (compared to previous studies and close to the maximum permitted exposure from a mobile phone handset), this particular nematode heat-shock protein gene is not up-regulated.

研究の種別:

研究助成

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