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

[携帯電話関連症状がある女性とない女性に対するW-CDMA携帯電話基地局短期ばく露の影響] med./bio.

Effects of short-term W-CDMA mobile phone base station exposure on women with or without mobile phone related symptoms

著者: Furubayashi T, Ushiyama A, Terao Y, Mizuno Y, Shirasawa K, Pongpaibool P, Simba AY, Wake K, Nishikawa M, Miyawaki K, Yasuda A, Uchiyama M, Yamashita HK, Masuda H, Hirota S, Takahashi M, Okano T, Inomata-Terada S, Sokejima S, Maruyama E, Watanabe S, Taki M, Ohkubo C, Ugawa Y
掲載誌: Bioelectromagnetics 2009; 30 (2): 100-113
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【目的】携帯電話関連症候群（MPRS）のある被験者は対照群に比べ、基地局からの電磁界の影響に対して敏感か否かを確認するための二重盲検、交差法による誘発試験を行う。【方法】 5000人の女性に質問紙郵送調査を行い、2474の有効回答を得た。この中から、MPRS群11人、対照群43人を集めた。4つのEMFばく露条件（連続ばく露、断続ばく露、騒音あり擬似ばく露、騒音なしの擬似ばく露）で、それぞれ30分間ばく露した。EMFは2.14GHz、10V/mであり、電波暗室内で基地局からの全身ばく露を模擬したものであるが、このばく露強度は基地局からの一般的受信強度よりやや高いレベルである。ばく露の前と後に心理学的および認知的パラメータを測定し、自律神経系機能をモニターした。また被験者には、EMFの感知とばく露中感じた不快感レベルの報告を依頼した。【結果】 MPRS群は対照群とEMFばく露の検知力に差異がなかった。それにもかかわらず、実際のEMFばく露の有無とは無関係に、また自律神経系機能における変化が現れないにもかかわらず、一貫して不快感を経験していた。したがって、両群とも、心理学的・認知的パラメータおよび自律神経系評価によれば、ばく露または擬似ばく露に対する反応に差異がなかった。【結論】基地局からのEMFばく露と電磁過敏症と因果関係の証拠はみられなかった。

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研究目的（著者による）

To measure the effects of short-term exposure to a W-CDMA mobile phone base station, and to observe whether they differ between women with mobile phone related symptoms and women without symptoms.

詳細情報

5000 questionaires including the frequency of mobile phone use and the presence/absence of mobile phone related symptoms were sent out to randomly sampled Japanese women (between 20 and 60 years). From 2472 valid responses 11 subjects with mobile phone related symptoms and 43 control subjects were recruited for a provocation study. Four different exposure conditions (each 30 min) were tested: continuous, intermittent, sham exposure with noise and sham exposure without noise.

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 2.14 GHz
ばく露時間: continuous for 30 min
  • 電界強度: 10 V/m effective value (at the head)
  • 電力密度: 0.265 W/m² effective value (at the head)
  • SAR: 0.0015 W/kg average over mass (whole body)
  • SAR: 0.0013 W/kg average over mass (brain)
  • SAR: 0.0078 W/kg peak (10 g) (in the brain)
  • SAR: 0.019 W/kg peak (10 g) (in the body)
ばく露2: 2.14 GHz
ばく露時間: intermittent, 5 min on or off, for 30 min
  • 電界強度: 10 V/m effective value (at the head)
  • 電力密度: 0.265 W/m² effective value (at the head)
  • SAR: 0.0015 W/kg average over mass (whole body)
  • SAR: 0.0013 W/kg average over mass (brain)
  • SAR: 0.0078 W/kg peak (10 g) (in the brain)
  • SAR: 0.019 W/kg peak (10 g) (in the body)

General information

There were four exposure conditions used: continuous EMF, intermittent EMF, sham, and noise exposure. During the tests performed on two days, each of the four conditions was administered to each subject in a double-blind, randomized order that was counterbalanced across subjects. Two sessions per day, each lasting about 90 min, were separated by at least 2 h.

ばく露1

主たる特性
周波数 2.14 GHz
タイプ
  • electromagnetic field
ばく露時間 continuous for 30 min
Modulation
Modulation type cf. additional information
Additional information

W-CDMA down-link signal similar to the one used in previous studies [Zwamborn et al., 2003; Regel et al., 2006] but with 64 dedicated physical channels added
ばく露装置
ばく露の発生源／構造
Distance between exposed object and exposure source 3 m
チャンバの詳細 The shielded room had an area of 5.3 x 3.0 m² and a height of 2.745 m, an ambient temperature of 23 °C, a humidity of 50%, and a sound level below 40 dBA. Flat wave absorbers (23.6 dB at 2.0 GHz) covered most of the floor, ceiling, and three walls in front of the horn antenna.
ばく露装置の詳細 The subject was seated on a polypropylene chair in front of a wooden desk with the psychological test equipment. The horn antenna, 1.15 m tall, was placed behind the subject and to the left at a height of 0.755 m being approximately that of an average Japanese female aged 20-59 sitting on a 0.4-m high chair.
Sham exposure A sham exposure was conducted.
Additional information The noise used was produced by and recorded near the RF power amplifier used in the experiment. The noise level at the subject's head position was 65 dBA.
パラメータ
測定量 値 種別 Method Mass 備考
電界強度 10 V/m effective value 測定値および計算値 - at the head
電力密度 0.265 W/m² effective value 測定値および計算値 - at the head
SAR 0.0015 W/kg average over mass 計算値 whole body -
SAR 0.0013 W/kg average over mass 計算値 brain -
SAR 0.0078 W/kg peak 計算値 10 g in the brain
SAR 0.019 W/kg peak 計算値 10 g in the body
Additional parameter details

The exposure level of 10 V/m is relatively high compared to the exposure level in the vicinity of a base station, which is reported to be around 0.01 W/m², or 1.94 V/m [Neubauer et al., 2007].

測定および計算の詳細

The input power level to the antenna was controlled with a fluctuation of less than 1% throughout the experiment. The electric field strength was also monitored using an isotropic electric field probe placed 1.5 m in front of and at the same height as the antenna. Uniformity of the electric field was verified in the area where the subject was seated. The electric field was 9.66 ± 1.64 V/m (rms) within a volume of 0.4 x 0.4 x 0.4 m³, where the head of the subject was expected to be during the experiments. The electromagnetic field and the SAR were simulated using the FDTD method and an adult human body model resembling a Japanese female [Nagaoka et al., 2004] in a sitting position, assuming plane waves. The peak SAR was found at the fingers.

ばく露2

主たる特性
周波数 2.14 GHz
タイプ
  • electromagnetic field
ばく露時間 intermittent, 5 min on or off, for 30 min
Modulation
Modulation type cf. additional information
Additional information

same as in E1
ばく露装置
ばく露の発生源／構造
  • E1と同じ装置
Additional information In the intermittent exposure condition, EMF was turned on or off randomly every 5 min. The on/off periods were counterbalanced, such that EMF was on and off for 50% of the time in each subject.
パラメータ
測定量 値 種別 Method Mass 備考
電界強度 10 V/m effective value 測定値および計算値 - at the head
電力密度 0.265 W/m² effective value 測定値および計算値 - at the head
SAR 0.0015 W/kg average over mass 計算値 whole body -
SAR 0.0013 W/kg average over mass 計算値 brain -
SAR 0.0078 W/kg peak 計算値 10 g in the brain
SAR 0.019 W/kg peak 計算値 10 g in the body

Reference articles

  • Neubauer G et al. (2007): [携帯電話基地局の健康影響可能性に関する将来の疫学研究の実行可能性]
  • Regel SJ et al. (2006): [UMTS基地局様ばく露、健康ならびに認知機能]
  • Nagaoka T et al. (2004): [日本人の平均の身長と体重をもった男女の全身高分解能ボクセルモデルの開発とラジオ周波数電磁界ドジメトリへの適用]
  • Zwamborn APM et al. (2003): [主観的愁訴のある人および無い人を被験者とした安寧および認知機能に対するGSM無線周波電磁界の影響]

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 group with mobile phone related symptoms did not differ significantly from the controls in their ability to detect exposure to electromagnetic fields. Discomfort and negative mood was significantly greater in the group with mobile phone related symptoms than in the control groups, irrespective of whether the electromagnetic field was actually on or off. The two groups did not differ in their responses to real or sham exposure according to any psychological, cognitive or autonomic measure.
The authors did not find a link between hypersensitivity symptoms and exposure to electromagnetic fields from base stations.

研究の種別:

研究助成

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