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

[デジタル無線電話からの無線周波エネルギーへの非熱的ばく露はL929細胞でのオルニチンデカルボキシラーゼ活性に影響しない] med./bio.

Non-thermal exposure to radiofrequency energy from digital wireless phones does not affect ornithine decarboxylase activity in L929 cells

著者: Desta AB, Owen RD, Cress LW
掲載誌: Radiat Res 2003; 160 (4): 488-491
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この研究は、835 MHz時分割多元接続（TDMA）無線電話からの無線周波（RF）電磁放射ばく露を受けた培養L929マウス線維芽細胞におけるオルニチン脱炭酸酵素（ODC）活性の変化の有無を調べた。ばく露時間は8時間、平均比吸収率（SAR）は、< 1 W / kgから15 W / kgまでの範囲で実験した。ばく露後に細胞を採取し、ODC活性を測定した。その結果、ばく露群と擬似ばく露群（非熱的レベルのSARでばく露）の間に、ODC活性の有意な差はなかった；培地に測定可能な加熱が生じるSARレベルにおいては、SAR量に依存した酵素活性低下が観察された；これは、RF以外の方法での加熱により生じる同程度の活性低下と一致した、と報告している。

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研究目的（著者による）

Murine cells were exposed to radiofrequency irradiation from a time division multiple access (TDMA) mobile phone operating at 835 MHz frequency to determine the effect of irradiation on ornithine decarboxylase (ODC) activity in cultured cells.

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 835 MHz
Modulation type: pulsed
ばく露時間: continuous for 8 h
  • 電力: 3 mW maximum (0.25; 0.50; 0.75; 1.0; 1.5; 2.0; 2.5; 3.0 mW)
  • SAR: 1 W/kg maximum (non-thermal)
  • SAR: 5 W/kg maximum (1-5 W/kg)
  • SAR: 10 W/kg maximum (6-10 W/kg)
  • SAR: 15 W/kg maximum (11-15 W/kg)

ばく露1

主たる特性
周波数 835 MHz
タイプ
  • electromagnetic field
特性
  • guided field
ばく露時間 continuous for 8 h
Modulation
Modulation type pulsed
Pulse width 6.7 ms
Additional information

TDMA
ばく露装置
ばく露の発生源／構造
  • セルラ－電話
  • Crawford cell (47.8 cm high x 22.9 cm deep x 15.2 cm wide)
チャンバの詳細 The Crawford cell and a sham-exposure chamber with similar dimensions were placed in the same water-jacketed incubator maintained at 37°C.
ばく露装置の詳細 Four 25-cm² flasks were placed in each exposure chamber with two flasks on each shelf. Effects of different temperatures in the absence of an RF field were examined in two satellite chambers (Plexiglas boxes receiving a controlled air flow from the central incubator).
Additional information Though the exposure system produced a non-uniform spatial distribution of the absorbed power it was not replaced by a better one because the aim of the study was to reproduce the results obtained in the reference article. In addition, the longer exposure time chosen was expected to result in a more homogeneous temperature distribution.
パラメータ
測定量 値 種別 Method Mass 備考
電力 3 mW maximum 測定値 - 0.25; 0.50; 0.75; 1.0; 1.5; 2.0; 2.5; 3.0 mW
SAR 1 W/kg maximum 測定値 - non-thermal
SAR 5 W/kg maximum 測定値 - 1-5 W/kg
SAR 10 W/kg maximum 測定値 - 6-10 W/kg
SAR 15 W/kg maximum 測定値 - 11-15 W/kg
測定および計算の詳細

Forward and reflected powers were monitored using power meters, transmitted power was not measured. The temperature of one flask in each chamber was monitored continuously using a non-perturbing probe. The SAR was calculated from the plots of temperature over time.

Reference articles

  • Litovitz TA et al. (1993): [オルニチン脱炭酸酵素活性へのマイクロ波の影響におけるコヒーレンス時間の役割]

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）

No statistically significant difference in ornithine decarboxylase activity was found between exposed and sham-exposed cells at non-thermal specific absorption rates (SARs). At SARs which resulted in measurable heating of the medium, a dose-dependent decrease in enzymatic activity was observed. It was shown to be consistent with a comparable decrease caused by non-radiofrequency irradiation heating. Thus the authors observed only the well-known enzyme inhibition due to heating, rather than the previously reported enhancement attributed to radiofrequency exposure (e.g. publication 3382 and publication 9896).

研究の種別:

研究助成

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