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

[無線周波数放射への長期ばく露後のマウスの赤血球の小核頻度] med./bio.

Micronucleus frequency in erythrocytes of mice after long-term exposure to radiofrequency radiation

著者: Juutilainen J, Heikkinen P, Soikkeli H, Maki-Paakkanen J
掲載誌: Int J Radiat Biol 2007; 83 (4): 213-220
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【目的】この研究の目的は、赤血球の小核を測定することによって、無線周波数(RF)電磁界に対する長期ばく露の遺伝毒性を調査することであった。RF電磁界の発がん性への影響の可能性を評価するため、二つの動物実験において、血液サンプルが収集された。【方法】研究Aにおいて、メスのCBA/Sマウスに78週間(1.5時間/日、5日/週)の信号ばく露が行われた。信号は、アナログNMT(北欧携帯電話)電話に似せた902.5MHz連続信号を全身比吸収率(SAR)1.5W/kgで、またはデジタルGSM電話に似せた902.4MHzパルス信号をSAR0.35W/kgでばく露した。3番目のグループは擬似ばく露され、4番目のグループはケージコントロールとした。ケージコントロールとされた動物以外の全てに、実験の最初の3週間に渡り、X線4グレイ(Gy)が照射された。研究Bにおいて、メスの遺伝子組み換えマウス(line K2)とそれらの非遺伝子組み換えの同腹仔に、52週間(1.5時間/日、5日/週)のばく露が行われた。2つのデジタル携帯電話信号、GSMおよびDAMPS(デジタル最新式携帯電話システム)が0.5W/kgで用いられた。ケージコントロールされた動物以外の全てに、1.2MED(最小紅斑線量)の紫外線が1週間に3回照射された。【結果と結論】多染性または正染性赤血球における小核頻度に対するRF電磁界のいかなる影響も示されない結果となった。3つの異なる携帯電話の信号についての、人の携帯電話ばく露に相当する3つのSARレベルでの52週間または78週間のばく露後に、2つのマウス実験系において（および2番目の実験系における遺伝子組み換えという変異において）、結果は首尾一貫していた。

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研究目的（著者による）

To study genotoxicity of long-term exposure to radiofrequency electromagnetic fields by measuring of micronuclei formation in erythrocytes. Two animal studies evaluating possible cocarcinogenic effects of radiofrequency electromagnetic fields were performed.

詳細情報

Study 1: Female CBA/S mice were exposed for 78 weeks to either a continuous signal similar to that emitted by analog NMT mobile phones (at 1.5 W/kg; n = 20) or to a pulsed signal similar to that of digital GSM mobile phones (at 0.35 W/kg; n = 20). A third group was sham exposed (n = 20), and a fourth group served as cage controls (n = 19). All but the cage control mice were exposed to 4 Gy of x-rays during the three first weeks of the experiment.
Study 2: Female transgenic mice (line K2; n = 20) and their non-transgenic littermates (n = 20) were exposed for 52 weeks. Two digital mobile phone signals, GSM and D-AMPS were used at 0.5 W/kg. All but the cage control mice (n = 14) were exposed 3 times per week to an ultraviolet radiation dose of 1.2 MED (minimum erythema dose; i.e. 240 J/m²).

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 902.5 MHz
Modulation type: CW
ばく露時間: repeated daily exposure, 1.5 h/day, 5 days/week, for 78 weeks
NMT analog mobile phone
  • SAR: 1.5 W/kg average over time (whole body) ([Heikkinen et al., 2001])
ばく露2: 902.4 MHz
Modulation type: pulsed
ばく露時間: repeated daily exposure, 1.5 h/day, 5 days/week, for 78 weeks
GSM mobile phone
  • SAR: 0.35 W/kg average over time (whole body) ([Heikkinen et al., 2001])
ばく露3: 902.4 MHz
Modulation type: pulsed
ばく露時間: repeated daily exposure, 1.5 h/day, 5 days/week, for 52 weeks
GSM mobile phone
  • SAR: 0.5 W/kg average over time (whole body) ([Heikkinen et al., 2001])
ばく露4: 849 MHz
Modulation type: pulsed
ばく露時間: repeated daily exposure, 1.5 h/day, 5 days/week, for 52 weeks
DAMPS mobile phone
  • SAR: 0.5 W/kg average over time (whole body) ([Heikkinen et al., 2001])

ばく露1

主たる特性
周波数 902.5 MHz
タイプ
  • electromagnetic field
特性
  • guided field
ばく露時間 repeated daily exposure, 1.5 h/day, 5 days/week, for 78 weeks
Additional information NMT analog mobile phone
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 Three identical rectangular waveguide chambers made of aluminium were used for the two RF radiation exposure groups and the sham-exposed group. Exposure of 25 mice at a time was possible in one chamber. The exposure system was described in [Heikkinen et al., 2001].
ばく露装置の詳細 The mice were kept in small cylindrical acrylic restrainers (inner diameter 32 mm, length adjustable) placed on a Styrofoam holder in the center of the cross section of the waveguide with their longitudinal axes perpendicular to the EF and to the direction of propagation.
Sham exposure A sham exposure was conducted.
Additional information The output power was absorbed by a coaxial 10 W termination in both RF-exposure chambers.
パラメータ
測定量 値 種別 Method Mass 備考
SAR 1.5 W/kg average over time 電力損失による決定値 whole body [Heikkinen et al., 2001]
Additional parameter details

In study 1, all animals, except the cage-controls, were exposed to 4 Gy of X-rays in three equal fractions of 1.33 Gy at 1-week intervals during the first three weeks of the experiment [Heikkinen et al., 2001]. The background 50 Hz MFs were below 0.09 µT. The geomagnetic flux density measured with a fluxgate magnetometer varied between 41 and 54 µT (inclination 80-90°) in study 1.

測定および計算の詳細

The input, reflected and output powers were measured using RF power meters at the input and output of both exposure chambers. The SAR was controlled daily by adjusting the input power. The calculated maximum local SAR values inside the mice were 4-8 times higher than the whole-body average value and decreased with increasing animal size.

ばく露2

主たる特性
周波数 902.4 MHz
タイプ
  • electromagnetic field
特性
  • guided field
ばく露時間 repeated daily exposure, 1.5 h/day, 5 days/week, for 78 weeks
Additional information GSM mobile phone
Modulation
Modulation type pulsed
Pulse width 0.577 ms
Repetition frequency 217 Hz
Additional information

Speech modulation was simulated using a random sequence of bytes.
ばく露装置
ばく露の発生源／構造
パラメータ
測定量 値 種別 Method Mass 備考
SAR 0.35 W/kg average over time 電力損失による決定値 whole body [Heikkinen et al., 2001]
Additional parameter details

study 1

ばく露3

主たる特性
周波数 902.4 MHz
タイプ
  • electromagnetic field
特性
  • guided field
ばく露時間 repeated daily exposure, 1.5 h/day, 5 days/week, for 52 weeks
Additional information GSM mobile phone
Modulation
Modulation type pulsed
Pulse width 0.577 ms
Repetition frequency 217 Hz
Additional information

Speech modulation was simulated using a random sequence of bytes.
ばく露装置
ばく露の発生源／構造
Sham exposure A sham exposure was conducted.
パラメータ
測定量 値 種別 Method Mass 備考
SAR 0.5 W/kg average over time 電力損失による決定値 whole body [Heikkinen et al., 2001]
Additional parameter details

In study 2, all animals, except the cage-controls, were exposed to UV radiation three times/week [Heikkinen et al., 2003] at 1.2 human MED (minimum erythema dose), i.e., a dose of 240 J/m², calculated according to the CIE (Commission Internationale de l'Eclairage) wavelength weighing function [McKinlay and Diffey, 1987]. The background 50 Hz MFs were below 0.09 µT. The geomagnetic flux density measured with a fluxgate magnetometer varied between 50 and 55 µT (inclination 60-80°) in study 2. The animals in study 2 were exposed to average ELF MFs (measured with a small calibrated coil) of 5 µT during shaving with an electric clipper and of 0.6-1.4 µT during the UV-exposure.

ばく露4

主たる特性
周波数 849 MHz
タイプ
  • electromagnetic field
特性
  • guided field
ばく露時間 repeated daily exposure, 1.5 h/day, 5 days/week, for 52 weeks
Additional information DAMPS mobile phone
Modulation
Modulation type pulsed
Pulse width 6.67 ms
Repetition frequency 50 Hz
Additional information

Speech modulation was simulated using a random sequence of bytes.
ばく露装置
ばく露の発生源／構造
  • 導波管
  • DAMPS mobile phone, computer-controlled
パラメータ
測定量 値 種別 Method Mass 備考
SAR 0.5 W/kg average over time 電力損失による決定値 whole body [Heikkinen et al., 2001]
Additional parameter details

study 2

Reference articles

  • Heikkinen P et al. (2003): [オルニチンデカルボキシラーゼトランスジェニックおよび非トランスジェニックマウスにおける紫外線誘発皮膚腫瘍形成に関する携帯電話放射電波の影響]
  • Heikkinen P et al. (2001): [マウスでのX線誘発腫瘍形成に対する携帯電話放射の影響]
  • McKinlay AF et al. (1987): A reference action spectrum for ultraviolet induced erythema in human skin

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:
調査の時期:
  • ばく露後

研究の主なアウトカム（著者による）

The data did not show any effects of radiofrequency electromagnetic fields on micronucleus frequency in erythrocytes. The findings were consistent in two mouse strains (and in a transgenic variant of the second strain), after 52 or 78 weeks of irradiation, at three SAR levels relevant to human exposure from mobile phones, and for three different mobile phone signals.

研究の種別:

研究助成

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