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

[450 MHz無線周波への管理的全身ばく露を受けたヒトボランティアの熱生理学的反応] med./bio.

Thermophysiological responses of human volunteers during controlled whole-body radio frequency exposure at 450 MHz

著者: Adair ER, Kelleher SA, Mack GW, Morocco TS
掲載誌: Bioelectromagnetics 1998; 19 (4): 232-245
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この研究は、450MHz連続波の無線周波（RF）電磁界に45分間、全身ばく露した7人の成人ボランティア（男性3人女性4人、年齢21－57歳）における熱産生と熱損失の体温調節反応を測定した。実験は、2つの電力密度（PD）（PDの局所ピーク値＝18および24mW/cm2、SARの局所ピーク値＝0.320[W/kg]/mWcm2）でのばく露を、それぞれ3種の環境温度（Ta＝24、28、31℃）で行った他、対照として3つのTaでRFなしで実験した。その結果、どのばく露条件でも、代謝的な熱産生に変化はなかった；背中と胸部の発汗速度の著しい増大（これは、TaおよびPDの両方と密接に関連した）により、皮膚が冷却され、深部体温(食道部)を正常レベルの0.1℃以内に保つ効果的調整が確保された；温感、快適度、発汗、温度の好みなどカテゴリー判断は、生理学的反応で測定された変化と一致した､などを報告している。

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研究目的（著者による）

To study thermoregulatory responses of heat production and heat loss in seven volunteers during exposure to 450 MHz continuous wave radiofrequency fields.

詳細情報

Two power densities were tested at each of three ambient temperatures (24, 28, and 31°C).

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 450 MHz
Modulation type: CW
ばく露時間: continuous for 45 min

ばく露1

主たる特性
周波数 450 MHz
タイプ
  • electromagnetic field
特性
  • far field
ばく露時間 continuous for 45 min
Modulation
Modulation type CW
ばく露装置
ばく露の発生源／構造
Distance between exposed object and exposure source 102 cm
チャンバの詳細 The anechoic chamber was 2.44 x 2.44 x 3.05 m. A small climate-conditioned cubicle was created by a 5-cm thick Styrofoam partition. The dipole antenna was mounted in a 90° aluminium corner reflector.
ばく露装置の詳細 Subjects wearing a bathing suit sat in a light plastic chair with their back towards the antenna. The electric field vector of the incident plane wave was aligned with the long axis of the subject's body (E-polarization).
Sham exposure A sham exposure was conducted.
Additional information After 30 min of equilibration to the prevailing temperature (24, 28, or 31 °C), the subjects were exposed or sham exposed for 45 min.
パラメータ
測定量 値 種別 Method Mass 備考
電力密度 18 mW/cm² maximum 測定値 - -
SAR 6 W/kg maximum 測定値 - at the surface
電力密度 24 mW/cm² maximum 測定値 - -
SAR 7.68 W/kg maximum 測定値 - at the surface
Additional parameter details

Power densities (PD) specified above were determined with the E-field probe placed on the antenna boresight at the location of the subject's center back. Verification measurements of these PDs were made at 2- to 3-week intervals during the course of the study.

測定および計算の詳細

Forward and reflected powers were monitored by power meters. Field uniformity at the subject's location was determined over a 60 x 90 cm plane centered on the boresight and at 130 cm from the antenna using a broadband isotropic radiation detector fitted with an E-field probe. PD across the central 20 x 40 cm portion of this plane showed a 14% nonuniformity with the chair present. Dosimetric evaluations were conducted on a 70-kg soft plastic mannequin model, 174 cm tall, filled with simulated muscle tissue and placed on the chair with its back at a distance of 102 cm from the antenna. After equilibration, the model was irradiated for 10 min at three PD values. The maximum surface SAR of 0.32 W/kg per mW/cm² was calculated from the greatest temperature rise occurring at the lower back [Chou et al., 1996]. A second set of temperature readings was taken for comparison with the probes inserted 2 cm below the surface and exposure for 45 min. SAR could, however, not be calculated from these because the E-field was unknown for the points.

Reference articles

  • Chou CK et al. (1996): [無線周波電磁界ばく露：実験的ドシメトリに関する教育的レビュー]

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）

No changes in metabolic heat production occurred under any irradiation conditions. Vigorous increases in sweating rate on back and chest, directly related to both ambient temperature and power densities, cooled the skin and ensured efficient regulation of the deep body temperature to within 0.1°C of the normal level.

研究の種別:

研究助成

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