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

[組織加熱レベルでのマウス脳のc‐fos発現を増加させるイリジウムばく露] med./bio.

IRIDIUM exposure increases c-fos expression in the mouse brain only at levels which likely result in tissue heating

著者: Morrissey JJ, Raney S, Heasley E, Rathinavelu P, Dauphinee M, Fallon JH
掲載誌: Neuroscience 1999; 92 (4): 1539-1546
RISフォーマットで参考文献をダウンロード

この研究は、マウスを1.6 GHzの無線周波の連続波またはパルス変調波（衛星電話サービスのIRIDIUM信号：変調周波数11 Hz、デューティサイクル4:1、パルス幅9.2 ms）に1時間ばく露し、脳内のc-fos遺伝子発現への影響を評価した。その結果、ばく露レベルが、携帯電話への人体ばく露の最大限度値と比較して、ピーク値で6倍、全身平均ばく露レベルで30倍を超過しない限り、マウス脳でのc-fosの発現は、有意に増加しなかった；それより高いレベルのばく露においては、連続波またはパルス変調波のいずれでも、c-fos発現は同程度に増加した；明らかにパルス変調波に特異的に見られる影響はなかった；高いばく露レベルにおける辺縁皮質および皮質下部領域におけるc-fos増加のパターンは、拘束下での熱知覚によるストレス応答および／または体温調節領域付近のニューロン活動との一貫性があるが、イリジウムエネルギーの脳組織とのいかなる直接相互作用とも整合しない、と報告している。

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研究目的（著者による）

To measure the expression of c-fos (a proto-oncogene) in sections of mouse brain tissue immediately following a 1h exposure to 1.6 GHz continuous wave (CW) and IRIDIUM RF (a ground-to-satellite-to-ground cellular communications web) up to SAR levels which exceed the maximal allowable FCC (Federal Communications Commission) limits.

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 1.6 GHz
Modulation type: CW
ばく露時間: continuous for 1 h
  • 電力: 3.25 W (0.1; 0.2; 0.5; 1.25; 3.25 W)
  • SAR: 7.79 W/kg (0.23; 0.48; 1.19; 2.99; 7.79 W/kg at rostral forebrain (0 mm bregma))
  • SAR: 7.14 W/kg (0.22; 0.44; 1.10; 2.75; 7.14 W/kg at mid-caudal forebrain (-2 mm bregma))
  • SAR: 11.21 W/kg average over mass (brain) (0.35; 0.69; 1.73; 4.31; 11.21 W/kg)
  • SAR: 26.29 W/kg maximum (0.8; 1.62; 4.05; 10.11; 26.29 W/kg at the neck)
  • SAR: 6.42 W/kg average over mass (whole body) (0.19; 0.39; 0.99; 2.47; 6.42 W/kg)
ばく露2: 1.6 GHz
Modulation type: pulsed
ばく露時間: continuous for 1 h
  • 電力: 3.25 W (0.1; 0.2; 0.5; 1.25; 3.25 W)
  • SAR: 7.79 W/kg (0.23; 0.48; 1.19; 2.99; 7.79 W/kg at rostral forebrain (0 mm bregma))
  • SAR: 7.14 W/kg (0.22; 0.44; 1.10; 2.75; 7.14 W/kg at mid-caudal forebrain (-2 mm bregma))
  • SAR: 11.21 W/kg average over mass (brain) (0.35; 0.69; 1.73; 4.31; 11.21 W/kg)
  • SAR: 26.29 W/kg maximum (0.8; 1.62; 4.05; 10.11; 26.29 W/kg at the neck)
  • SAR: 6.42 W/kg average over mass (whole body) (0.19; 0.39; 0.99; 2.47; 6.42 W/kg)

ばく露1

主たる特性
周波数 1.6 GHz
タイプ
  • electromagnetic field
特性
  • near field
ばく露時間 continuous for 1 h
Modulation
Modulation type CW
ばく露装置
ばく露の発生源／構造
Distance between exposed object and exposure source 5 mm
チャンバの詳細 The circular head-first and near-field Plexiglas carousel irradiator exposure system is described in the reference article.
ばく露装置の詳細 Five mice at a time were placed on a Plexiglas platform radially around (and with their noses 5 mm from the feedpoint of) a central resonant 0.5 λ dipole antenna and harnessed at the neck with a nylon tether.
Additional information Experiments also included untreated cage controls, sham-treated controls and Lindane positive controls for cortical c-fos expression.
パラメータ
測定量 値 種別 Method Mass 備考
電力 3.25 W - - - 0.1; 0.2; 0.5; 1.25; 3.25 W
SAR 7.79 W/kg - 測定値および計算値 - 0.23; 0.48; 1.19; 2.99; 7.79 W/kg at rostral forebrain (0 mm bregma)
SAR 7.14 W/kg - 測定値および計算値 - 0.22; 0.44; 1.10; 2.75; 7.14 W/kg at mid-caudal forebrain (-2 mm bregma)
SAR 11.21 W/kg average over mass 測定値および計算値 brain 0.35; 0.69; 1.73; 4.31; 11.21 W/kg
SAR 26.29 W/kg maximum 測定値および計算値 - 0.8; 1.62; 4.05; 10.11; 26.29 W/kg at the neck
SAR 6.42 W/kg average over mass 測定値および計算値 whole body 0.19; 0.39; 0.99; 2.47; 6.42 W/kg
Additional parameter details

2.39 ± 0.74 W/kg/W in the caudate-putamen at the level of the rostral forebrain 2.21 ± 0.75 W/kg/W in the posterior thalamic nucleus at the level of the mid-caudal forebrain

測定および計算の詳細

Methods for determining SAR values for this study are described in the reference article. Briefly, temperature changes of mouse cadavers during a 1-min exposure at 25 W of input power were measured with a temperature probe inserted into the brain. The calculated SAR values were then used as reference points for the extrapolation of a thermographic infrared image of a sagittally sectioned mouse cadaver after a similar exposure.

ばく露2

主たる特性
周波数 1.6 GHz
タイプ
  • electromagnetic field
特性
  • near field
ばく露時間 continuous for 1 h
Modulation
Modulation type pulsed
Pulse width 9.2 ms
Duty cycle 25 %
Repetition frequency 11 Hz
Additional information

IRIDIUM signal
ばく露装置
ばく露の発生源／構造
  • E1と同じ装置
Distance between exposed object and exposure source 5 mm
パラメータ
測定量 値 種別 Method Mass 備考
電力 3.25 W - - - 0.1; 0.2; 0.5; 1.25; 3.25 W
SAR 7.79 W/kg - 測定値および計算値 - 0.23; 0.48; 1.19; 2.99; 7.79 W/kg at rostral forebrain (0 mm bregma)
SAR 7.14 W/kg - 測定値および計算値 - 0.22; 0.44; 1.10; 2.75; 7.14 W/kg at mid-caudal forebrain (-2 mm bregma)
SAR 11.21 W/kg average over mass 測定値および計算値 brain 0.35; 0.69; 1.73; 4.31; 11.21 W/kg
SAR 26.29 W/kg maximum 測定値および計算値 - 0.8; 1.62; 4.05; 10.11; 26.29 W/kg at the neck
SAR 6.42 W/kg average over mass 測定値および計算値 whole body 0.19; 0.39; 0.99; 2.47; 6.42 W/kg

Reference articles

  • Swicord M et al. (1999): [回転式照射器を用いて1.6 GHzマイクロ波にばく露したマウスに対するドシメトリ]

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:
  • ばく露後

研究の主なアウトカム（著者による）

The expression of c-fos was not significantly elevated in the brains of mice until exposure levels (SAR) exceeded 6 times the peak dose and 30 times the whole body average dose as maximal cellular telephone exposure limits in humans. Higher level exposure (continuos wave or IRIDIUM signal) elevated c-fos to a similar extent, what suggests no obvious pulsed modulation-specific effects. The pattern of c-fos elevation in limbic cortex and subcortex areas at higher exposure levels is most consistent with a stress response due to thermal perception. It is not consistent with any direct interaction of IRIDIUM energy with brain tissue.

研究の種別:

研究助成

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