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

[ヒトでのラジオ周波電磁界ばく露:脳でのSAR分布の推定、睡眠と心拍への影響] med./bio.

Radio frequency electromagnetic field exposure in humans: Estimation of SAR distribution in the brain, effects on sleep and heart rate.

掲載誌: Bioelectromagnetics 2003; 24 (4): 262-276

この研究は、デジタル無線電話のハンドセットから放射されるものと同様の無線周波電磁界RF EMF:900 MHz、空間ピークSAR =1 W / kg)のばく露を受けた健康な若い被験者における脳生理学的影響を調べた。第1実験は、夜間の8時間の睡眠中、断続的ばく露を行なった。第2実験は、日中の3時間の睡眠の前に30分間、脳の片側へのばく露を行なった。加えて、ばく露の変動性および不確かさの評価を含めた、脳領域の詳細なドシメトリーも実施した。その結果、擬似ばく露の対照条件下に比べ、ばく露条件下で、初期のレム睡眠時の脳電図(EEG)スペクトルパワーが、どちらの実験においても、9 - 14 Hzで増加した;2つの実験において、RF EMFばく露の影響に関して脳構造学上での差異は観察されなかった;覚醒中の片側ばく露であっても、両半球に同様の影響を引き起こした;睡眠中のばく露は、睡眠開始後の覚醒を減少させ、心拍変動に影響を与えた;睡眠前のばく露は、覚醒時および睡眠ステージ1における心拍数を低下させた;、と報告している。

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研究目的(著者による)

Extended analysis of the effects of radiofrequency electromagnetic field exposure with two different distributions of the SAR on EEG topography and on heart rate. Additionally, detailed dosimetry of the brain areas is presented.

詳細情報

In two previous studies the authors demonstrated that radiofrequency electromagnetic fields similar to those emitted by digital mobile phone handsets affect brain physiology of subjects exposed to radiofrequency electromagnetic fields either during sleep or during the waking period preceding sleep (see publication 758 and publication 4766).
First experiment: Subjects were exposed intermittently during an 8 h nighttime sleep episode (for details see publication 758).
Second experiment: Subjects were exposed unilaterally for 30 min prior to a 3 h daytime sleep episode (for details see publication 4766).

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 900 MHz
Modulation type: pulsed
ばく露時間: intermittent, 15 min on/off for 8 h
  • SAR: 1 W/kg maximum (10 g)
ばく露2: 900 MHz
Modulation type: pulsed
ばく露時間: continuous for 30 min
  • SAR: 1 W/kg maximum (10 g)

ばく露1

主たる特性
周波数 900 MHz
タイプ
  • electromagnetic field
特性
  • near field
ばく露時間 intermittent, 15 min on/off for 8 h
Modulation
Modulation type pulsed
Pulse width 0.577 ms
Duty cycle 12.5 %
Repetition frequency 217 Hz
Additional information

synthesized base station-like signal with seven bursts (slots 0-6) on and one off (slot 7); several frames of the multiframe (104 basic frames) were additionally modified; this signal structure resulted in the spectral components of 2, 8, and 217 Hz, plus the corresponding harmonics; the burst and the intermittency (20 µs) between the bursts led to additional components at 1733 Hz and 50 kHz

ばく露装置
ばく露の発生源/構造
Distance between exposed object and exposure source 30 cm
チャンバの詳細 absorber walls were placed around the antennas and the bed
ばく露装置の詳細 array of three half-wavelength dipole antennas (30 cm apart) mounted behind the head of the recumbent subject at a distance of 30 cm; distance between the top of the subject's head and the antenna array varied during sleep between 30-45 cm and the angle of incidence from -45° to 45°
Sham exposure A sham exposure was conducted.
パラメータ
測定量 種別 Method Mass 備考
SAR 1 W/kg maximum 備考を参照のこと。 10 g -

ばく露2

主たる特性
周波数 900 MHz
タイプ
  • electromagnetic field
特性
  • near field
ばく露時間 continuous for 30 min
Modulation
Modulation type pulsed
Additional information

same signal as in E1

ばく露装置
ばく露の発生源/構造
  • planar rectangular patch antennas
Distance between exposed object and exposure source 11 cm
ばく露装置の詳細 antennas mounted at both sides of the head at a distance of 115 ± 5 mm, with the center of the antenna at 42 ± 10 mm vertically above the ear canal
Sham exposure A sham exposure was conducted.
パラメータ
測定量 種別 Method Mass 備考
SAR 1 W/kg maximum 備考を参照のこと。 10 g -

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
  • ばく露後

研究の主なアウトカム(著者による)

Compared to sham exposure, spectral power of the non-REM sleep electroencephalogram was initially increased in the 9-14 Hz range in both experiments. No topographical differences with respect to the effect of radiofrequency electromagnetic field exposure were found in the two experiments. Even unilateral irradiation during waking induced a similar effect in both hemispheres. Exposure during sleep reduced waking after sleep onset and affected heart rate variability. Irradiation prior to sleep reduced heart rate during waking and stage 1 sleep.
Simulations of the SAR distribution within the brain support the interpretation that subcortical structures may be responsible for the revealed effect on the sleep EEG.

研究の種別:

研究助成

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