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

[子牛のメラトニンレベルへの超低周波磁界ばく露の影響は季節によって異なる] med./bio.

Effect of exposure to extremely low frequency magnetic fields on melatonin levels in calves is seasonally dependent.

掲載誌: Sci Rep 2015; 5: 14206

この研究は、50Hz、数100nTレベルの超低周波磁界(ELFMF)にばく露した子牛(1-2月齢)の唾液中のメラトニン(MLT)を測定した。その結果、冬期にはMLT分泌に対するELFMFの抑制的影響が観察され、夏期にはELFMFばく露による唾液中のMLT濃度の上昇が観察された;冬期の抑制作用の方が夏期の増進作用より強かった、と報告している。

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研究目的(著者による)

The effects of exposure of calves to a 50 Hz magnetic field in two different seasons (summer and winter) on the salivary melatonin levels should be investigated.

詳細情報

Two sessions were conducted: one session in the summer and the other one in the winter. For each session, 8 calves were divided into an exposure group and a control group (n=4 each) with equal numbers of male and females in each group (remark EMF-Portal: it is not clear how many animals of each breed were used and how the control groups were treated). Different animals were used for each session.
During each session, samples were taken on days 0, 10, 20, 30 and 35. Every sampling day involved four samples from each calf, collected at 12.00 noon, 10.30 p.m., 02.00 a.m. and 04.30 a.m..

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 50 Hz
ばく露時間: continuous (?) for 35 days
summer exposure
  • 磁束密度: 0.39 µT minimum (measurement on sampling days only; location of measurement not stated)
  • 磁束密度: 0.41 µT maximum (measurement on sampling days only; location of measurement not stated)
ばく露2: 50 Hz
ばく露時間: continuous (?) for 35 days
winter exposure
  • 磁束密度: 0.39 µT minimum (measurement on sampling days only; location of measurement not stated)
  • 磁束密度: 0.41 µT maximum (measurement on sampling days only; location of measurement not stated)

ばく露1

主たる特性
周波数 50 Hz
タイプ
  • magnetic field
波形
  • sinusoidal
ばく露時間 continuous (?) for 35 days
Additional information summer exposure
ばく露装置
ばく露の発生源/構造
チャンバの詳細 wooden boxes (closed to 3 sides, access to an open enclosure through the fourth) in a stable
ばく露装置の詳細 the wooden boxes (one calve per box) were oriented with the longer axis along 17°/197° and this was also the main direction of the oscillation of the artificial magnetic field; the coils consisted of 6 turns of coaxial cable (shielded to prevent the generation of electrical fields) wrapped around a box (remark EMF-Portal: it is not clear if animals had free access to the open enclosure in front of their boxes); the average ambient temperature (in the enclosure outside the boxes) was 26.2°C during the summer session
Additional information at 12.00 h, about 85 lx were measured in the enclosure and up to 20 lx were measured inside the boxes; at night, the light intensity was always below the detection threshold
パラメータ
測定量 種別 Method Mass 備考
磁束密度 0.39 µT minimum 測定値 - measurement on sampling days only; location of measurement not stated
磁束密度 0.41 µT maximum 測定値 - measurement on sampling days only; location of measurement not stated

ばく露2

主たる特性
周波数 50 Hz
タイプ
  • magnetic field
波形
  • sinusoidal
ばく露時間 continuous (?) for 35 days
Additional information winter exposure
ばく露装置
ばく露の発生源/構造
  • E1と同じ装置
ばく露装置の詳細 the average ambient temperature (in the enclosure outside the boxes) was 2.7°C during the winter
Additional information light intensity in winter during the day (12.00 h) was around 30 lx in the open enclosure in front of the boxes and 0 lx inside the boxes; at night, the light intensity was always below the detection threshold
パラメータ
測定量 種別 Method Mass 備考
磁束密度 0.39 µT minimum 測定値 - measurement on sampling days only; location of measurement not stated
磁束密度 0.41 µT maximum 測定値 - measurement on sampling days only; location of measurement not stated

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 average melatonin level in the exposure group was significantly higher in the summer and significantly lower in winter compared to the respective control group. Moreover, females showed significantly higher melatonin levels than males in both seasons and in both groups.
The authors conclude that exposure of calves to a 50 Hz magnetic field might influence the melatonin level as a function of the season. They recommend to consider seasonal factors (photoperiod and temperature) in future studies.

研究の種別:

研究助成

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