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

[1970 MHz UMTSばく露のヒト視覚感知に影響しない] med./bio.

No influence on selected parameters of human visual perception of 1970 MHz UMTS-like exposure

著者: Schmid G, Sauter C, Stepansky R, Lobentanz IS, Zeitlhofer J
掲載誌: Bioelectromagnetics 2005; 26 (4): 243-250
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この研究は、1.97 GHz UMTS様信号へのばく露がヒトの視覚機能に及ぼす影響の可能性を、健康なボランティア被験者58人（男性29人、女性29人；平均年齢29±5.1歳）を対象に二重ブラインド化、クロスオーバー試験で調べた。各被験者は、視覚認識のいくつかのパラメータを評価するために、4つの異なる臨床試験のバッテリーを3回（高ばく露、低ばく露および擬似のばく露セッションにおいて）受けた。被験者の頭部ばく露に用いた信号は、代表的なUMTS携帯電話RF放射を模擬した（一定の受信状態および送信電力が大きく変化する状態（つまり信号エンベロープに低周波成分が含まれている状態）を含ませた）。高ばく露条件では、脳の左側頭葉の皮質での1 g平均SARは0.63 W / kg、10 g平均SARは0.37 W / kgであった。低ばく露条件では高ばく露の10分の1、擬似ばく露では低ばく露より少なくとも50 dB低かった（100,000分の1）。その結果、得られた試験成績の統計的評価により、ばく露条件と擬似ばく露との間に、調査された視覚パラメータの有意差は認められなかった、と報告している。無線周波（RF）電磁界のヒト認知脳機能への影響に関するこれまでの研究において、作業タスクは、例えばコンピューター画面上で、被験者に視覚的に提示された。したがって、もし影響があるとしても、視覚認識、脳の処理、および反応という経路のどこで影響が起こるかという興味深い問題が残っている。今回の研究で、視覚パラメータに限っては有意な差は認められなかった、と結論している。

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研究目的（著者による）

To study possible effects of exposure to a generic 1.97 GHz UMTS-like signal on human visual perception.

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: see add. information
  • SAR: 0.63 W/kg mean (1 g) (0.25-1.49 W/kg)
  • SAR: 0.37 W/kg mean (10 g) (0.16-0.84 W/kg)

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 see add. information
Modulation
Modulation type cf. additional information
Additional information

Generic UMTS test signal developed for use in bio-electromagnetic experiments (see reference article) and representing a wideband code division multiple access (WCDMA) signal at a carrier frequency close to the uplink frequency band of UMTS in frequency division duplex (FDD) mode. Due to simulated fading and power control, the signal envelope contained low frequency components of 8-12 and 1,500 Hz.
ばく露装置
ばく露の発生源／構造
  • UMTS test signal generator, helical antennas
チャンバの詳細 laterally shielded exposure cabin with the inner surface covered by pyramidal RF absorbing material
ばく露装置の詳細 Test subjects wore a special head set consisting of a modified stereo head phone (all metallic parts removed) with small matched helical antennas mounted in a way to achieve an exposure distribution in the head similar to the case of mobile phone usage. Subjects were exposed only at the left side of the head, but they were not informed about this fact.
Additional information Each subject was tested on a single week day between 3:30 and 7:00 p.m. and underwent four tests used for assessing visual perception under three different exposure conditions (high exposure, low exposure, and sham exposure) that were controlled randomly and double-blinded by control software. Additionally, all tests except the Critical Flicker and Fusion Frequency Test were presented to the subjects under a positive control condition (flicker light applied from the back) at the end of the subject's session.
パラメータ
測定量 値 種別 Method Mass 備考
SAR 0.63 W/kg mean 測定値および計算値 1 g 0.25-1.49 W/kg
SAR 0.37 W/kg mean 測定値および計算値 10 g 0.16-0.84 W/kg
Additional parameter details

SAR values indicated resulted in the cortex of the left temporal lobe of the brain in the high exposure condition. Low exposure condition was defined to be one tenth of high exposure, and sham was at least 50 dB below low exposure. Background ambient field strength measured in the frequency range from DC up to 18 GHz was found to be negligible.

測定および計算の詳細

A detailed dosimetric analysis of the exposure system was based on the power recordings (forward as well as reverse power measurements) obtained during the experiments and extensive numerical simulations using the SEMCAD simulation platform and the anatomical European male head model at a spatial resolution of 1.5-3 mm. The validity of the numerical model of the small helical antennas used was verified prior to the dosimetric analysis by comparisons of experimental and numerical results, showing deviations of less than ±5%. Furthermore, the SAR inside the homogeneous specific anthropomorphic mannequin (SAM) phantom measured using an automated SAR test facility (DASY 3) agreed within ±10% with corresponding SEMCAD calculations. The minimum and maximum values of SAR to be expected in the test subjects' temporal cortex were obtained by an uncertainty analysis, the main contribution (~85%) being due to the variations of the antenna's position with respect to the head, caused by different head sizes and shapes.

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:
  • 感覚器
調査の時期:
  • ばく露中

研究の主なアウトカム（著者による）

Statistical evaluation of the obtained data revealed no statistically significant differences in the investigated parameters of visual perception between the exposure conditions and sham exposure.

研究の種別:

研究助成

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