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

[携帯電話が放射する電磁界の感知] med./bio.

Perception of the electromagnetic field emitted by a mobile phone

著者: Kwon MS, Koivisto M, Laine M, Hämäläinen H
掲載誌: Bioelectromagnetics 2008; 29 (2): 154-159
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背景と目的：電磁界感受性とは電磁界を感知する能力を意味し、電磁界ばく露が原因であると思ってしまう健康上の症状の発症は必ずしも伴わない。若い健常者を対象に電磁界感受性について誘発実験を行った。方法：若い成人の健康な被験者84人に、GSM携帯電話電磁界（217 Hzでパルス変調した902 MHzの電磁界）の感知に関する2種類の強制選択課題を実施した。第1課題「電磁界がONであったか？」、第2課題「電磁界が変化したか？」である。第1課題における3条件（ON・OFFが各50％、ON=100%、OFF=100%）、第2課題における3条件（ON→OFF・OFF→ONが50％、ON→ON=100%、OFF→OFF=100%）の各条件を100回試行し、合計で600試行を実施した。600試行において75％以上の正答率の被験者には賞金を与えることを前もって通知した。結果：成績は偶然による期待値より高くはなく、誰も賞金を獲得しなかった。2人の被験者が第1課題（100試行）において97%（P=1.28×10-25）と94%（P=9.40×10-22）という極端な成績を示したが、1ヶ月後に実施した同じ6つ条件についての再検査で結果は再現されなかった。事前の質問紙において携帯電話電磁界を感知できると報告していた6人の被験者はその他の被験者より高い成績を示さなかった。結論：本研究は携帯電話電磁界に対する感受性の存在を否定する経験的証拠を提出した。

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研究目的（著者による）

In this in vivo study the possible existence of electrosensibility to mobile phone electromagnetic fields should be tested in a large sample of the general population.

詳細情報

Eighty-four young healthy adults (mean age: 24 +/- 6 years; 57 females, 27 males) participated. 100 trials each lasting 5 seconds were performed per experimental condition.
In the first task the participants should estimate whether the electromagnetic field was "on" or "off" and in the second task whether the electromagnetic field changed (from "on" to "off" and the other way round) or no electromagnetic field change occurred (always "on" or "off").

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: pulsed
ばく露時間: intermittent, 5 s on or off and a pause for reaction plus 1 s, repeated 100 times
on/off task
  • SAR: 1.21 W/kg maximum
  • SAR: 1.14 W/kg average over mass (1 g)
  • SAR: 0.82 W/kg average over mass (10 g)
ばく露2: 902 MHz
Modulation type: pulsed
ばく露時間: intermittent, 2.5 s on/off or off/on and a pause for reaction plus 1 s, repeated 100 times
change task
  • SAR: 1.21 W/kg maximum
  • SAR: 1.14 W/kg average over mass (1 g)
  • SAR: 0.82 W/kg average over mass (10 g)

General information

There were 100 trials in each condition, and the four conditions other than the genuine on/off and the change condition had the same exposure types, either on or off. The order of the tasks and the conditions within each task were counterbalanced, and the trials were randomized in the genuine on/off and the change conditions and in effect double-blinded by computer. Participants could take a break between test blocks.

ばく露1

主たる特性
周波数 902 MHz
タイプ
  • electromagnetic field
ばく露時間 intermittent, 5 s on or off and a pause for reaction plus 1 s, repeated 100 times
Additional information on/off task
Modulation
Modulation type pulsed
Pulse width 0.58 ms
Repetition frequency 217 Hz
ばく露装置
ばく露の発生源／構造
  • セルラ－電話
  • GSM, with loudspeaker and buzzer removed, connected to a signal generator by a 10 m cable
チャンバの詳細 Participants performed the tasks sitting 1.5 m away from a computer monitor in a soundproof room.
ばく露装置の詳細 The mobile phone was attached to a headset and placed on the ear (parallel to the medial plane in a normal use position) on the side usually used for mobile phone conversations or reported to be more sensitive to the EMF (67 right and 17 left).
Additional information The on/off task consisted of one genuine on/off condition, where the EMF was either on or off with the probability of 50% each, and two other conditions where the EMF was either always on or always off.
パラメータ
測定量 値 種別 Method Mass 備考
SAR 1.21 W/kg maximum 測定値 - -
SAR 1.14 W/kg average over mass 測定値 1 g -
SAR 0.82 W/kg average over mass 測定値 10 g -
Additional parameter details

Earplug-shaped earphones were inserted into both ears to deliver masking white noise.

測定および計算の詳細

The output power from the generator-amplifier setup was measured using an RF power meter roughly every tenth session. The SAR was measured before and after the modification using a Dosimetric Assessment System (DASY4) and a generic twin phantom filled with head tissue simulating liquid. The phone was in the left cheek position, and the SAR was maximum near the position of the removed loudspeaker on the ear [Haarala et al., 2007].

ばく露2

主たる特性
周波数 902 MHz
タイプ
  • electromagnetic field
ばく露時間 intermittent, 2.5 s on/off or off/on and a pause for reaction plus 1 s, repeated 100 times
Additional information change task
Modulation
Modulation type pulsed
Pulse width 0.58 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
Additional information The change task consisted of one genuine change condition, where the EMF was either first on and then off or first off and then on with the probability of 50% each, and two constant conditions where the EMF was either always on or always off.
パラメータ
測定量 値 種別 Method Mass 備考
SAR 1.21 W/kg maximum 測定値 - -
SAR 1.14 W/kg average over mass 測定値 1 g -
SAR 0.82 W/kg average over mass 測定値 10 g -

Reference articles

  • Haarala C et al. (2007): [左または右脳半球への携帯電話のパルス波および連続波のばく露：人の認知機能への影響]

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:
  • ばく露前
  • ばく露中
  • ばく露後

研究の主なアウトカム（著者による）

The results of right attribution whether electromagnetic field was "on", "off" or changing were not higher than expected by chance. Therefore, this study could not prove the existence of electrosensibility to mobile phone electromagnetic fields.

研究の種別:

研究助成

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