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

[認知処理中の脳の振動性活動に対するパルス波および連続波の902MHz携帯電話ばく露の影響] med./bio.

Effects of pulsed and continuous wave 902 MHz mobile phone exposure on brain oscillatory activity during cognitive processing.

掲載誌: Bioelectromagnetics 2007; 28 (4): 296-308

今回の二重盲検試験の目的は、Krauseその他による研究[2000a, b, 2004]を部分的に再現すること、および、認知処理中における事象関連の非同期/同期(ERD/ERS)脳電図(EEG)反応に対する携帯電話(MP)から放射された電磁界(EMF)の影響の可能性を更に調査することであった。36人の男性から成る2つのグループが集められた。以下の6つのばく露条件下で、1つのグループでは聴覚記憶タスクが遂行され、他のグループでは視覚作業記憶タスクが遂行された。ばく露条件は、左側および右側への、SHAM(EMFのない、擬似ばく露)、CW(連続波EMF)、PM(パルス変調されたEMF)のばく露である。ばく露中、脳電図(EEG)が記録された。以前の我々の研究と一致して、EMFへのばく露は、アルファ波帯(8-12Hz)における脳の振動性応答に対する穏やかな影響があったが、行動指標に対する影響はなかった。しかし、EEGへの影響は変動があり、体系的でもなく、以前の報告との一貫性もなかった。脳の振動性応答に対するEMFの影響は微妙で、変動性があり、理由は不明ながら再現が困難であると、我々は結論した。

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研究目的(著者による)

The aim of the study was to partially replicate the data of previous studies (publication 10459, publication 5719, and publication 3600) and to further investigate the possible effects of electromagnetic fields emitted by mobile phones on the event related desynchronisation/synchronisation (ERD/ERS) EEG responses during cognitive processing.

詳細情報

One group of 36 male subjects performed an auditory memory task and another group (also 36 male participants) performed a visual working memory task in six exposure conditions: sham exposure, continuous wave electromagnetic field exposure and pulse modulated electromagnetic field exposure during both left- and right-side exposure, while the EEG was recorded.
The same cognitive tasks as in the previous studies were used.

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 902 MHz
Modulation type: CW
ばく露時間: continuous for about 54 or 80 min
  • 電力: 0.25 W mean
  • SAR: 0.738 W/kg average over mass (10 g)
  • SAR: 1.1 W/kg average over mass (1 g)
  • SAR: 1.18 W/kg peak
ばく露2: 902 MHz
Modulation type: pulsed
ばく露時間: continuous for about 54 or 80 min
  • 電力: 0.25 W mean
  • SAR: 0.738 W/kg average over mass (10 g)
  • SAR: 1.1 W/kg average over mass (1 g)
  • SAR: 1.18 W/kg peak

General information

In both experiments, testing was conducted in three sessions (CW, PM, and sham exposure), separated by 1 week, each session with left-sided and right-sided exposure. The exposure conditions were counterbalanced, and a double-blind design was used.

ばく露1

主たる特性
周波数 902 MHz
タイプ
  • electromagnetic field
ばく露時間 continuous for about 54 or 80 min
Modulation
Modulation type CW
ばく露装置
ばく露の発生源/構造
  • dummy mobile phone antenna, signal generator
Distance between exposed object and exposure source 20 mm
チャンバの詳細 The subjects were seated in a comfortable chair approx. 1.6 m from a computer screen. The signal generator and the power amplifier were located in an adjacent room.
ばく露装置の詳細 The dummy mobile phone was attached to the subject's head using an earmuff without metal parts, in which one of the protectors was replaced. The phone was positioned as in normal use. The antenna was located approx. 20 mm from the scalp over the posterior temporal lobe in the left-side exposure, and over the inferior and posterior temporal lobe in the right-side exposure. The difference between the exposure sides was due to the asymmetrical position of the antenna.
Sham exposure A sham exposure was conducted.
Additional information The EMF head-set was originally designed and built by Preece et al. [2005].
パラメータ
測定量 種別 Method Mass 備考
電力 0.25 W mean 測定値 - -
SAR 0.738 W/kg average over mass 測定値 10 g -
SAR 1.1 W/kg average over mass 測定値 1 g -
SAR 1.18 W/kg peak 測定値 - -

ばく露2

主たる特性
周波数 902 MHz
タイプ
  • electromagnetic field
ばく露時間 continuous for about 54 or 80 min
Modulation
Modulation type pulsed
Pulse width 0.577 ms
Repetition frequency 217 Hz
ばく露装置
ばく露の発生源/構造
  • E1と同じ装置
パラメータ
測定量 種別 Method Mass 備考
電力 0.25 W mean 測定値 - -
SAR 0.738 W/kg average over mass 測定値 10 g -
SAR 1.1 W/kg average over mass 測定値 1 g -
SAR 1.18 W/kg peak 測定値 - -

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)

In line with the previous studies, the authors observed that the electromagnetic field exposure had modest effects on brain oscillatory responses in the alpha wave range (approximately 8-12 Hz) and had no effects on the behavioural measures. The only statistically significant effect arose during the auditory working memory task between the pulse modulated and continuous wave exposure conditions, such that greater alpha wave ERS and smaller alpha wave ERD responses were recorded during the pulse modulated exposure condition as compared to continuous wave exposure condition.The effects on the EEG ERD/ERS responses were, however, varying, unsystematic and inconsistent with previous reports.
The authors conclude that the effects of electromagnetic fields on brain oscillatory responses may be subtle, variable and difficult to replicate for unknown reasons.

研究の種別:

研究助成

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