この研究は、雄および雌のSDラットを用い、50Hz正弦波磁界（S-50 Hz MF）とホルムアルデヒドの同時ばく露の相乗的発がん作用可能性を評価した。一つのグループは出生前から自然死までの全期間S-50Hz MFばく露を受け、かつ6週齢から104週間にわたり飲料水を介してホルムアルデヒドを摂取した。他の2つのグループはMFまたはホルムアルデヒドのいずれか1つのばく露を受け、もう一つのグループは無処置対照とした。その結果、共ばく露の雄ラットにおいて、対照に比べ、悪性腫瘍、甲状腺C細胞がん、血液リンパ細網系新生物の発生率が有意に上昇した；雌ラットでは有意差が観察されなかった､と報告している。
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The carcinogenic effects of life-span co-exposure of rats to a 50 Hz magnetic field and formaldehyde should be investigated.
The present study is part of a large EMF animal test project, which has already been described in Soffritti et al. 2010.
In previous research, the authors found a slight, non-significantly increased incidence of cancer in rats exposed to 50 mg/l formaldehyde. This concentration was also used in this study, administered from 6 to 104 weeks of age via the drinking water.
Rats were divided into the following groups: 1) exposure to a magnetic field (253 males, 270 females), 2) co-exposure to a magnetic field and formaldehyde (200 males, 203 females), 3) exposure to formaldehyde (200 males, 202 females), 4) unexposed control group (500 males, 501 females). All the animals were exposed and observed until death.
ばく露時間: continuous from 6 weeks of age until death (max. 104 weeks)
|ばく露時間||continuous from 6 weeks of age until death (max. 104 weeks)|
|チャンバの詳細||rats in cages were placed in a large room with a temperature of 22°C ± 3°C and a relative humidity of 40-60%|
|ばく露装置の詳細||the field lines were horizontal and parallel to the ground; the field uniformity was better than 10%; there was no noise or vibration from current generator and coils; a maximum variation of 2°C was tolerated near coils; the 24 coils had a toroidal shape and were made of three turns of an insulated copper cable, mounted on a superstructure of aluminum composed of two insulated parts in order to avoid a closed loop subject to total field; the total copper cross-section was 11 mm x 28 mm; mounted inside the toroidal magnet was a wooden support structure for rat cages; each toroidal device was designed for the allocation of 500 rats, 5 per cage, distributed on five levels; the toroidal device had an external diameter of 4.7 m and was 2.1 m high|
|Additional information||control animals stayed in the same room as the exposed animals|
A significantly increased incidence of malignant tumors, thyroid C-cell carcinomas and lymphomas/leukemias was observed in male rats co-exposed to the magnetic field and formaldehyde (group 2) compared to rats only exposed to the magnetic field (group 1) or the control group (group 4). No statistically significant differences were observed between males of group 2 and group 3 (formaldehyde only) and between female animals of all groups.
The authors conclude that there might be a synergy between life-span exposure of rats to a 50 Hz magnetic field and formaldehyde in terms of carcinogenicity.