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

[UMTS携帯電話のような1.97 GHz電磁場は、人間の注意力と反応時間への影響はない] med./bio.

No effect of an UMTS mobile phone-like electromagnetic field of 1.97 GHz on human attention and reaction time

著者: Unterlechner M, Sauter C, Schmid G, Zeitlhofer J
掲載誌: Bioelectromagnetics 2008; 29 (2): 145-153
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過去のいくつかの研究で、GSM携帯電話の電磁波放射が人間の反応時間に影響を与えることが報告された。けれども現在のところ、UMTS携帯電話によって放射された電磁場の推定される影響を扱った研究で利用可能なものはごくわずかである。我々の研究において、40人の平均年齢26.0歳(21～30歳)の健常な被験者(男性20人、女性20人)が、4つの異なるコンピューターテストを受け、3つの異なるUMTS携帯電話のようなばく露状態(2つのばく露レベル、さらに、疑似ばく露)のもとに反応時間と注意力を計測された。被験者へのばく露は、頭部近くで操作された小型螺旋アンテナによって行われ、UMTS携帯電話の放射を代表する汎用信号によって、常時受信状態のもとに、さらに強変更送信電力状態のもとでも、送電された。高ばく露状態において、脳の左側頭葉の皮質において被験者に生じたピーク空間平均ばく露は、1g平均SARに関しては0.63W/kg(最小0.25W/kg、最大1.49W/kg)、10g平均SARに関しては0.37W/kg(最小0.16W/kg、最大0.84W/kg)であった。低ばく露状態は高ばく露状態の10分の1で、疑似ばく露は低ばく露より少なくとも50dB小さかった。得られたテストパラメーターの統計的解析は、汎用UMTS信号に対するばく露は注意あるいは反応に対する統計的に重要な直接的影響がなかったことを、明らかにした。従って、この研究は、UMTS携帯電話のばく露は、短期ばく露状態のもとで注意に干渉するという如何なる証拠も提供しない。

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研究目的(acc. to editor)

To study the effect of an UMTS mobile phone-like electromagnetic field of 1.97 GHz on human attention and reaction time.

詳細情報

40 healthy volunteers (20 female, 20 male) were exposed at three different UMTS mobile phone-like exposure conditions (two exposure levels plus sham exposure).

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 1.97 GHz
ばく露時間: session lasting about 1.5 h
  • SAR: 0.63 W/kg maximum (1 g) (0.25-1.49 W/kg)
  • SAR: 0.37 W/kg maximum (10 g) (0.16-0.84 W/kg)
  • SAR: 1.67 W/kg maximum (10 g)

ばく露1

主たる特性
周波数 1.97 GHz
タイプ
  • electromagnetic field
ばく露時間 session lasting about 1.5 h
Modulation
Modulation type cf. additional information
Additional information

generic UMTS (WCDMA) test signal [Ndoumbe Mbonjo Mbonjo et al., 2004] including low frequency components of 1500 Hz, simulating power control, and 8-12 Hz, simulating 30 dB power variation due to fading
ばく露装置
ばく露の発生源／構造
  • helical antennas, UMTS test signal generator
チャンバの詳細 The exposure cabin was laterally shielded and lined with RF absorbing material. The exposure system used has been described in [Schmid et al., 2005].
ばく露装置の詳細 Subjects were exposed on the left side of the head using small matched helical antennas built in a modified stereo head phone without metallic parts. They were not informed about the exposure side.
Sham exposure A sham exposure was conducted.
Additional information Each subject participated in three testing sessions held at the same time in the afternoon of three separate working days between 10 and 12 days apart. Each testing session consisted of the same four tests done three times under the different exposure levels (high, low, and sham). After each individual test, the participants left the exposure cabin for a standardized break of 3 min. The orders of both the tests and the exposure levels were chosen pseudo-randomly and double-blinded by the control software. Over all three sessions, the duration of exposure was approximately the same for all subjects.
パラメータ
測定量 値 種別 Method Mass 備考
SAR 0.63 W/kg maximum 計算値 1 g 0.25-1.49 W/kg
SAR 0.37 W/kg maximum 計算値 10 g 0.16-0.84 W/kg
SAR 1.67 W/kg maximum 測定値 10 g -
Additional parameter details

Indicated above are the resulting peak spatial average exposure values in the cortex of the left temporal lobe of the brain in the high exposure condition. Low exposure was one tenth of high exposure, and sham was at least 50 dB below low exposure. Background ambient field strengths measured in the frequency range from DC up to 18 GHz were found to be negligible (max. values, e.g., 50 Hz: 3 V/m, 35 nT; 72 Hz: 1 V/m, 240 nT; 92.5 kHz: 100 nT).

測定および計算の詳細

Forward and reverse powers were continuously recorded every 30 s. A detailed dosimetric analysis was performed by computations (including a thorough uncertainty analysis) using an anatomical numerical head model based on the Visible Human dataset and compared to measurements using a homogeneous specific anthropomorphic mannequin (SAM) head phantom which is routinely used in mobile phone compliance testing. Both methods showed a good agreement within ±10% in terms of the maximum 1 and 10 g averaged SAR [Schmid et al., 2005].

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:
研究対象とした臓器系:
調査の時期:
  • ばく露中

研究の主なアウトカム（著者による）

The data showed that exposure to the UMTS signal under these experimental conditions had no statistically significant immediate effect on attention or reaction time. There were no significant differences between the test parameters under the three different exposure conditions in any of the four tests performed.
As in the present study UMTS exposure was applied, the data cannot be easily compared with earlier studies investigating GSM exposure.

研究の種別:

研究助成

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