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

[2450 MHzパルスまたはCW電磁界へのヒトボランティアの局所ばく露は類似した体温調節反応を起こす] med./bio.

Partial-body exposure of human volunteers to 2450 MHz pulsed or CW fields provokes similar thermoregulatory responses

著者: Adair ER, Mylacraine KS, Cobb BL
掲載誌: Bioelectromagnetics 2001; 22 (4): 246-259
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この研究は、同一の周波数、同一の電力密度（PD）の連続波（CW）とパルス波（PW）への全身ばく露が人体に同じ体温調節反応を起こすか否かを検証した。これまでに、リスザルでは、2450MHzのCWとPWに対する体温調節反応がほぼ同じであることが示されている。この研究では、2450MHzのCWとPW（パルス幅65μs、パルスの繰り返し回数104pps）のばく露実験に別々のボランティアグループ（男性5人と女性2人および男性3人と女性3人）を用い、環境温度（Ta＝24、28、31℃）の管理下で、標準化した手順（30分間のベースライン、45分間のRFまたは擬似ばく露時、10分間のベースライン）で、熱産生と熱損失の体温調節反応（食道および皮膚6部位の温度、代謝熱産生、局所皮膚血流、局所発汗速度）を測定した。PDは、0、27、35 mW/cm2 、それぞれのSARは、0、5.94、7.7 W/kgとした。その結果、両グループとも、全てのばく露条件で、深部体温および代謝熱産生の変化は最小であり、CWとPWのばく露による違いは見られなかった､と報告している。

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研究目的（著者による）

To study thermoregulatory responses of heat production and heat loss in two different groups of volunteers during exposure to 2450 MHz radiofrequency fields (continuous wave and pulsed wave) at 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: 2,450 MHz
Modulation type: CW
ばく露時間: continuous for 45 min
ばく露2: 2,450 MHz
Modulation type: pulsed
ばく露時間: continuous for 45 min

General information

The 2450 MHz human exposure system, field measurements, and dosimetry have been described in detail in a previous publication [Adair et al., 1999].

ばく露1

主たる特性
周波数 2,450 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
チャンバの詳細 The anechoic chamber was 2.45 m x 2.45 m x 3.66 m in which a small climate-conditioned cubicle was created by a 5-cm thick Styrofoam partition.
ばく露装置の詳細 Subjects wearing a bathing suit sat on a light plastic chair, facing the rear chamber wall.
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 27 mW/cm² maximum 測定値 - -
SAR 5.94 W/kg maximum 測定値 - at the surface
電力密度 35 mW/cm² maximum 測定値 - -
SAR 7.7 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. These PDs were verified every few weeks during the course of each experiment.

測定および計算の詳細

A broadband isotropic radiation monitor, fitted with an E-field probe, was used to map the field at the location of the subject's chair [Adair et al., 1999]. PD measurements across the central 25 x 45 cm portion of a 65 x 80 cm plane at the location of the subject's back showed a nonuniformity of ~13% at CW and ~12% at PW exposure, with the chair absent. Dosimetric measurements were conducted on a 70-kg soft plastic mannequin filled with muscle equivalent material. The normalized maximum surface SAR (W/kg per mW/cm²) was calculated from the greatest temperature rise occurring at the lower back [Chou et al., 1996].

ばく露2

主たる特性
周波数 2,450 MHz
タイプ
  • electromagnetic field
特性
  • far field
ばく露時間 continuous for 45 min
Modulation
Modulation type pulsed
Pulse width 65 µs
Repetition frequency 10 kHz
ばく露装置
ばく露の発生源／構造
  • E1と同じ装置
Sham exposure A sham exposure was conducted.
パラメータ
測定量 値 種別 Method Mass 備考
電力密度 27 mW/cm² maximum 測定値 - -
SAR 5.94 W/kg maximum 測定値 - at the surface
電力密度 35 mW/cm² maximum 測定値 - -
SAR 7.7 W/kg maximum 測定値 - at the surface

Reference articles

  • Adair ER et al. (1999): [2つの無線周波（450および2450 MHz）への人体のばく露：生理学的反応の類似と差異]
  • 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）

Mean data for each group showed minimal changes in core temperature and metabolic heat production for all test conditions and no reliable differences between continuous wave and pulsed wave irradiation. Local skin temperatures showed similar trends for continuous wave and pulsed wave irradiation that were power density-dependent. Only the skin temperature of the upper back (facing the antenna) showed a reliably greater increase during pulsed wave exposure than during continuous wave exposure.
Local sweat rate and skin blood flow were both ambient temperature and power density-dependent and showed greater variability than other measures between continuous wave and pulsed wave irradiations; this variability was attributable primarily to the characteristics of the two different subject groups. With one noted exception, no clear evidence for a differential response to continuous wave and pulsed wave fields was revealed.

研究の種別:

研究助成

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