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

[生理学的相互作用プロセスと無線周波エネルギ吸収] med./bio.

Physiological interaction processes and radio-frequency energy absorption

著者: Adair ER, Adams BW, Hartman SK
掲載誌: Bioelectromagnetics 1992; 13 (6): 497-512
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この研究は、身体と共振する周波数の電磁界ばく露によって生じる深部体温の上昇について、動物モデルで、反応が変化する閾値および体温調節による補償の定常状態を検討した。成獣雄リスザルに、寒冷な無反射チャンバ内でアンテナの遠方界で450または2450 MHz連続波（E偏波）のばく露を10分間または90分間与えた。全身SARは、0-6 W/kg（450 MHz）および0-9 W/kg（2,450 MHz)であった。直腸と皮膚の温度、代謝による熱産生、蒸散による熱損失を連続モニタした。その結果、寒冷環境での短時間のばく露中では、代謝熱の産生低下はSAR値に直接比例したが、2450MHzエネルギーの方が共振周波数より効果的な刺激となった；定常状態では、深部体温の規則的上昇が共振周波数で見られた、などを報告している。

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研究目的（著者による）

The question was tested whether the thermoregulatory system might somehow be overwhelmed by exposures at resonance at higher whole-body SARs, even in environments conducive to efficient heat dissipation.

詳細情報

Hyperthermia has been examined in an animal model to determine both the thresholds for response change and the steady-state thermoregulatory compensation for body heating during exposure at resonant (450 MHz) and supra-resonant (2450 MHz, data previously collected) frequencies.

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: repeated exposures for 5 x 10 min separated by 20-min intervals
  • 電力密度: 6 mW/cm² (2, 3, 4, 5, and 6 mW/cm²)
  • SAR: 2.5 W/kg mean (whole body) (0.83, 1.24, 1.65, 2.08, and 2.48 W/kg)
ばく露2: 450 MHz
Modulation type: CW
ばく露時間: continuous for 90 min
  • 電力密度: 15 mW/cm² (2, 5, 8, 11, and 15 mW/cm²)
  • SAR: 6 W/kg mean (whole body) (0.83, 2.08, 3.3, 4.54, and 6.1 W/kg)
ばく露3: 2,450 MHz
Modulation type: CW
ばく露時間: repeated exposures for 5 x 10 min separated by re-equilibration intervals
  • SAR: 3.75 W/kg mean (whole body) (0.5-3.75 W/kg)
ばく露4: 2,450 MHz
Modulation type: CW
ばく露時間: continuous for 90 min
  • SAR: 9 W/kg mean (whole body) (0.5-9 W/kg)

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 repeated exposures for 5 x 10 min separated by 20-min intervals
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 130 cm
チャンバの詳細 The anechoic chamber was 2.44 m x 2.44 m x 3.05 m. The half-wave dipole antenna was mounted in a 90° corner reflector.
ばく露装置の詳細 Monkeys were restrained in a chair inside a ventilated Styrofoam test compartment (30 cm x 33 cm x 78 cm). The electric field vector of the incident plane wave was aligned with the long axis of the animal's body (E-polarization).
Sham exposure A sham exposure was conducted.
Additional information After 90 min of equilibration, the monkey received five 10-min MW exposures of increasing power density separated by 20-min intervals. Three such sessions were conducted on each monkey at each ambient temperature (15, 20, 25, or 30 °C).
パラメータ
測定量 値 種別 Method Mass 備考
電力密度 6 mW/cm² - 測定値 - 2, 3, 4, 5, and 6 mW/cm²
SAR 2.5 W/kg mean 測定値 whole body 0.83, 1.24, 1.65, 2.08, and 2.48 W/kg
測定および計算の詳細

Field uniformity at the animal's location was determined over a 40 x 50 cm plane centered on the boresight and at 130 cm from the antenna using a broadband isotropic radiation detector with a field probe. Power density across the central 20 x 40 cm portion of this plane showed an 18% nonuniformity with the chair present. Whole-body SAR values (across a range of 5-20 mW/cm² at the animal's chest) were calculated from the mean temperature rise produced at 3 depths in 2 sizes of saline filled cylindrical Styrofoam models during 10-min exposures according to the procedure of Adair and Adams [1982]. The average SAR determined as 0.413 W/kg per mW/cm² was later confirmed by measurement of the colonic temperature of conscious monkeys.

ばく露2

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 90 min
Modulation
Modulation type CW
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.
Additional information Following equilibration, the monkey was exposed to a single power density for 90 min at 20 °C. Three sessions were conducted on each monkey at each power density.
パラメータ
測定量 値 種別 Method Mass 備考
電力密度 15 mW/cm² - 測定値 - 2, 5, 8, 11, and 15 mW/cm²
SAR 6 W/kg mean 測定値 whole body 0.83, 2.08, 3.3, 4.54, and 6.1 W/kg

ばく露3

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 repeated exposures for 5 x 10 min separated by re-equilibration intervals
Modulation
Modulation type CW
ばく露装置
ばく露の発生源／構造
  • 詳細不明
Additional information Earlier data collected on comparable groups of animals, exposed to 2,450-MHz CW fields in environments similar to E1 [Adair and Adams, 1982; Adair, 1987] was compared to data from the present experiments.
パラメータ
測定量 値 種別 Method Mass 備考
SAR 3.75 W/kg mean 測定値 whole body 0.5-3.75 W/kg

ばく露4

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 90 min
Additional information Adair ER (1987): Microwave challenges to the thermoregulatory system. USAF Report SAM-TR-87-7, August. Brooks AFB, TX: School of Aerospace Medicine.
Modulation
Modulation type CW
ばく露装置
ばく露の発生源／構造
  • 詳細不明
Additional information Earlier 2,450-MHz data collected under protocols identical to E2 [Adair, 1987] was compared to data from the present experiments.
パラメータ
測定量 値 種別 Method Mass 備考
SAR 9 W/kg mean 測定値 whole body 0.5-9 W/kg

Reference articles

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

研究の主なアウトカム（著者による）

The reduction of metabolic heat production was directly proportional to the SAR during brief radiofrequency exposures in the cold. 2450 MHz energy was a more efficient stimulus than was 450 MHz. In the steady state, a regulated increase in deep body temperature accompanied exposure at resonance, not unlike that which occurs during exercise. The results indicate that temperature changes in the skin are the primary source of the neural signal for a change in physiological interaction processes during radiofrequency exposure in the cold.

研究の種別:

研究助成

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