Schüz J, Grigat J P, Störmer B, Rippin G, Brinkmann K, Michaelis J
Institut für Medizinische Statistik und Dokumentation, University of Mainz, Germany.
Radiat Environ Biophys. 2000 Dec;39(4):233-40. doi: 10.1007/s004110000068.
We examined the results of 1,835 magnetic field measurements in German residences conducted between November 1997 and September 1999. The measurements were part of an epidemiological study on the relationship between magnetic fields and childhood leukemia. We performed a fixed-location measurement of the magnetic field at 50 Hz and 16 2/3 Hz (frequency of the German railway system) over 24 h in the child's bedroom in the residence of each study participant. In addition, we conducted a second 24 h-measurement in the living room at 50 Hz, and spot measurements while walking through all rooms of the respective dwelling. Median 50 Hz magnetic fields above 0.2 muT were found to be infrequent in Germany (only 1.4% of all residences). Fields produced by high-voltage power lines (123-420 kV) were lower than expected: the median magnetic field was above 0.2 muT in only 8 (32.0%) of 25 residences located 50 m or closer to a high-voltage power line indicating that power lines in Germany are usually run well below the maximum power load. We found that magnetic fields were correlated with the type of residence and higher magnetic fields were measured in apartment buildings. There was also some evidence for a positive correlation between magnetic fields and traffic density and an inverse association between magnetic fields and family net income. The 24 h-magnetic field measurements correlated well with the spot measurements (r>0.7). However, when dichotomized with a cut-off point of 0.2 muT, there was only a poor agreement between the two measurement methods. A loss of the strength of the association after categorization was also observed when comparing the arithmetic mean and median of the same 24 h-measurement. In summary, these analyses give a valuable overview of magnetic field distributions in German residences.
我们研究了1997年11月至1999年9月间在德国住宅进行的1835次磁场测量结果。这些测量是一项关于磁场与儿童白血病关系的流行病学研究的一部分。我们在每位研究参与者住宅内儿童卧室中，对50赫兹和16又2/3赫兹（德国铁路系统频率）的磁场进行了24小时的固定位置测量。此外，我们在客厅对50赫兹的磁场进行了第二次24小时测量，并在走过各住宅所有房间时进行了现场测量。在德国，50赫兹磁场中值高于0.2微特斯拉的情况并不常见（仅占所有住宅的1.4%）。高压输电线（123 - 420千伏）产生的磁场低于预期：在距离高压输电线50米或更近的25所住宅中，只有8所（32.0%）的磁场中值高于0.2微特斯拉，这表明德国的输电线通常运行在远低于最大功率负荷的水平。我们发现磁场与住宅类型相关，在公寓楼中测得的磁场更高。还有一些证据表明磁场与交通密度呈正相关，与家庭净收入呈负相关。24小时磁场测量与现场测量相关性良好（r>0.7）。然而，当以0.2微特斯拉为分界点进行二分法划分时，两种测量方法之间的一致性较差。在比较同一24小时测量的算术平均值和中值时，分类后关联强度也有所损失。总之，这些分析提供了德国住宅磁场分布的宝贵概述。
