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

[携帯電話による頭痛：二重盲検法および擬似ばく露を統制した誘発研究] med./bio.

Mobile phone headache: a double blind, sham-controlled provocation study

著者: Oftedal G, Straume A, Johnsson A, Stovner LJ
掲載誌: Cephalalgia 2007; 27 (5): 447-455
RISフォーマットで参考文献をダウンロード

本研究は、携帯電話からの無線周波(RF)電磁界へのばく露が頭痛や不快の原因であるか否か、また、症状を一般的電磁界ではなく携帯電話に起因すると考える人において、それが生理学的変数に影響を及ぼすか否かを調べる目的で行われた。オープン法での誘発試験でこれらの症状を経験した17人の適格者が、交差デザインの無作為化二重盲検法による誘発研究に参加した。擬似ばく露と携帯電話RFばく露を一対として、65対の試験が実施された。(視覚的アナログ尺度での)苦痛や不快の上昇は、RFばく露セッションでは10.1、擬似ばく露セッションでは12.6だった(P＝0.30)。心拍数、血圧の変化はばく露の種類と関連しなかった(P＝0.30-0.88)。この研究では携帯電話からのRF電磁界が頭痛や不快の原因である、または生理学的変数に影響を及ぼすという証拠は得られなかった。症状の最もありそうな原因はノセボ効果である。

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研究目的（著者による）

To study whether exposure to radiofrequency electromagnetic fields from mobile phones would result in more headache or discomfort than sham exposure and to test possible effects on physiological parameters such as heart rate and blood pressure.

詳細情報

17 eligible individuals, who experienced symptoms (symptoms to mobile phones, but not to electromagnetic fields in general) in a provocation test, took part in the study.

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 902.4 MHz
Modulation type: pulsed
ばく露時間: continuous for 30 min
  • SAR: 1 W/kg cf. remarks (1 g) (spatial peak)
  • SAR: 0.8 W/kg average over mass (10 g)

General information

Seventeen subjects took part in a double-blind, randomized provocation study with cross-over design. Sixty-five pairs of sham and mobile phone RF exposures were applied. Each subject was allowed to take part in a maximum of four randomized pairs of trials, at least 2 days apart, among which, the RF session came first twice. A test session lasted almost 2 h, allowing for an adaptation and rest period.

ばく露1

主たる特性
周波数 902.4 MHz
タイプ
  • electromagnetic field
ばく露時間 continuous for 30 min
Modulation
Modulation type pulsed
Duty cycle 12.5 %
Repetition frequency 217 Hz
ばく露装置
ばく露の発生源／構造
  • セルラ－電話
  • GSM, power amplifier
Distance between exposed object and exposure source 8.5 cm
チャンバの詳細 The exposure system was the same as in [Wilen et al., 2006]. The exposure equipment, except for the antennas, was placed in a control room next to the shielded exposure room. The subjects were comfortably seated while looking at videos showing nature and wildlife films.
ばく露装置の詳細 Two wall-mounted base station antennas [Huber et al., 2003] were mounted symmetrically at 8.5 cm from the sides of the subject's head, the movements of which were restricted sideways by wooden bars.
Sham exposure A sham exposure was conducted.
Additional information A power divider directed a part of the signal to one of the antennas or to an ohmic load (sham exposure) and another part to a power meter. The exposure was given on the subject's preferred side or selected by chance.
パラメータ
測定量 値 種別 Method Mass 備考
SAR 1 W/kg cf. remarks - 1 g spatial peak
SAR 0.8 W/kg average over mass - 10 g -
Additional parameter details

The maximum background level of RF signals from GSM base stations was -105 dBm in the exposure room. For an hour after the exposure, the subjects were in an adjacent room where the maximum signal level was -78 dBm.

測定および計算の詳細

The SAR was relatively uniformly distributed over a large area around the ear [Wilen et al., 2006].

Reference articles

  • Wilen J et al. (2006): [携帯電話に関連する疾病兆候を持つ患者の心理物理試験と感応]
  • Huber R et al. (2003): [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]

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 data gave no evidence that radiofrequency electromagnetic fields from mobile phones may cause headache or discomfort or influence physiological variables (heart rate, blood pressure).

研究の種別:

研究助成

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