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

[In vitroでの携帯電話ラジオ周波数電磁界にばく露されたMolt-4Tリンパ球細胞でのDNA損傷] med./bio.

DNA damage in Molt-4 T-lymphoblastoid cells exposed to cellular telephone radiofrequency fields in vitro

著者: Phillips JL, Ivaschuk O, Ishida-Jones T, Jones RA, Campbell-Beachler M, Haggren W
掲載誌: Bioelectrochem Bioenerg 1998; 45 (1): 103-110
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この研究は、モルト-4 Tリンパ芽球細胞に、813.5625MHz（iDEN携帯電話の周波数）および836.55MHz（TDMA携帯電話の周波数）のパルス信号のばく露を与え、その影響を調べた。非熱的影響を調べるために、低SARでばく露された（iDEN信号は平均2.4および24 μWg -1、TDMA信号は平均2.6および26 μWg -1）。アルカリコメットアッセイ、または単一細胞ゲル電気泳動アッセイを用いて、細胞培養物中のDNA一本鎖切断を測定した。ばく露条件ごとにすべての実験データをプールし、単一のグループとして分析した。その結果、2.4μWg（-1）のSARで2時間または21時間のiDEN信号ばく露群では、DNA損傷が有意に減少した；2.6μWg（-1）のSARで2時間または21時間のTDMA信号ばく露群では、DNA損傷が有意に減少した; 3）24μWg（-1）のSARで2時間および21時間のiDEN信号ばく露群では、DNA損傷が有意に増加した； 26μWg（-1）のSARで2時間のTDMA信号ばく露群では、DNA損傷が有意に減少した、と報告している。

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研究目的（著者による）

To detect DNA single-strand breaks in lymphoblastoid cells exposed for short (2 and 3h) and long (21h) periods to pulsed signals at cellular telephones frequencies (813.5625 MHz and 836.55 MHz).

詳細情報

The studies were perfomed at low SAR to look for athermal radiofrequency radiation effects.

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 813.5625 MHz
Modulation type: pulsed
ばく露時間: intermittent 20 min on/off for 2, 3 and 21 hours
ばく露2: 836.55 MHz
Modulation type: pulsed
ばく露時間: intermittent 20 min on/off for 2, 3 and 21 hours

ばく露1

主たる特性
周波数 813.5625 MHz
タイプ
  • electromagnetic field
特性
  • guided field
ばく露時間 intermittent 20 min on/off for 2, 3 and 21 hours
Modulation
Modulation type pulsed
Pulse width 15 ms
Repetition frequency 22.22 Hz
Additional information

iDEN: time-domain multiplexing in which each second is broken down into a series of about 22 frames, each of 45 ms duration. Each frame is divided into three 15 ms slots. This results in RF carrier bursts of 15 ms duration, repeating at 45 ms intervals, at the mobile phone and the head of the user. The brief amplitude training pulse included at the leading edge of each slot is transmitted once every 200 frames (i.e. every 9 s) at 10 times the slot average power.
ばく露装置
ばく露の発生源／構造
チャンバの詳細 Two TEM cells of 18 x 18 x 9 cm (both above and below the septum) were housed in a single incubator. They were each powered (exposed) or unpowered (sham).
ばく露装置の詳細 One 60-mm Petri dish with 5 ml of medium was placed on a 1.5 cm platform of styrene plastic which was placed centrally along the longitudinal axis on the septum in a region of reasonably uniform E-field normal to the dish.
Additional information The exposure pattern resulted in total exposure durations of 1, 1.67 and 10.67, respectively. There was no detectable rise in temperature at any power density used in these experiments. The ambient 60 Hz magnetic field outside the TEM cells was 0.13 ± 0.02 µT rms and 0.20 ± 0.04 µT rms.
パラメータ
測定量 値 種別 Method Mass 備考
電力 450 mW - 測定値 - -
電力密度 0.8 mW/cm² - - - -
SAR 2.4 µW/g mean 計算値 - ± 0.3 µW/g
電力 4.5 W - 測定値 - -
SAR 24 µW/g mean 計算値 - -
Additional parameter details

SAR values indicated are slot averages.

測定および計算の詳細

The amplifier output was measured by a directional coupler, a power sensor and a power meter which was connected to a chart recorder for permanent recording. Before each series of experiments the power at the TEM cell input was confirmed with another power sensor and a digital power meter. The experimental conditions were based on dosimetric assessments for this system with exposure to iDEN performed by Kuster et al. (1996) using the MAFIA electromagnetic simulation tool (see second reference article).

ばく露2

主たる特性
周波数 836.55 MHz
タイプ
  • electromagnetic field
特性
  • guided field
ばく露時間 intermittent 20 min on/off for 2, 3 and 21 hours
Modulation
Modulation type pulsed
Additional information

North American Dual-Mode Cellular (NADC) with TDMA
ばく露装置
ばく露の発生源／構造
Additional information The exposure pattern resulted in total exposure durations of 1, 1.67 and 10.67, respectively.
パラメータ
測定量 値 種別 Method Mass 備考
電力 510 mW - 測定値 - -
電力密度 0.9 mW/cm² - - - -
SAR 2.6 µW/g mean 計算値 - ± 1.9 µW/g
電力 5.1 W - 測定値 - -
SAR 26 µW/g mean 計算値 - -
Additional parameter details

SAR values indicated are slot averages.

測定および計算の詳細

A power meter/chart recorder combination connected to a directional coupler provided constant monitoring of forward power.

Reference articles

  • Ivaschuk OI et al. (1997): [変調された836.55 MHz無線周波電磁界への神経成長因子処置されたPC12ラット褐色細胞腫細胞のばく露：c-Junおよびc-Fosの発現への影響]
  • Burkhardt M et al. (1996): [ペトリ皿ばく露装置の数値計算および実験によるドシメトリ]

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:
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 results indicate that exposure of the cells to two different radiofrequency signals under athermal conditions altered the amount of DNA single-strand breaks. Exposure of cells to the iDEN signal (SAR of 2.4 µW/g, 2 or 21h) significantly decreased DNA damage and exposure at an SAR of 24 µW/g (2 or 21h) significantly increased DNA damage. Exposure of cells to the TDMA signal (SAR of 2.6 µW/g, 2 or 21h) and exposure at an SAR of 26 µW/g for 2h significantly decreased DNA damage.

研究の種別:

研究助成

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