Valjus J, Hongisto M, Verkasalo P, Järvinen P, Heikkilä K, Koskenvuo M
Environmental Protection Division, Imatran Voima Oy, Vantaa, Finland.
Bioelectromagnetics. 1995;16(6):365-76. doi: 10.1002/bem.2250160604.
In a specific case, the magnetic field generated in a building by a nearby power line is usually easy to calculate, although the accuracy of these calculations is sensitive to the quality of source information. To be able to study public health dimensions of magnetic field exposure (e.g., risk of cancer), it is necessary to evaluate the size and exposure of the population at risk. Relatively little quantitative information on public exposure to power-frequency magnetic fields of high-voltage power lines is available. This report describes residential exposure to magnetic fields from 110 kV, 220 kV, and 400 kV power lines in Finland at the national level, including 90% of the total line length in 1989. A geographical information system (GIS) was used to identify the buildings located near the power lines. After determining the distances between the lines and the buildings, historical data on load currents of these lines were used to calculate the magnetic fields. The residential magnetic field histories were then linked to the residents by means of a computerized central population register. The data obtained on personal exposure have also been utilized in a nationwide epidemiological study on magnetic field exposure of power lines and risk of cancer. The methods of exposure assessment and results of the number of buildings near 110 kV, 220 kV, and 400 kV power lines, their average annual magnetic fields, and personal exposure to magnetic fields from these lines are described. We found that 15,600 residents lived in an average residential magnetic field > or = 0.1 microT caused by power lines in 1989. The number of these residents increased fivefold during 1970-1989. We estimated that 0.3% of the population was exposed in their residences to an annual average magnetic flux density from 110 kV, 220 kV, and 400 kV power lines higher than 0.1 microT, the level that the background magnetic flux density in general does not exceed in Finnish homes. Thus, the problem of magnetic field exposure generated by high-voltage lines concerns only a relatively small fraction of the total population in Finland. However, the size and exposure of the population at risk remain somewhat arbitrary in practical multisource situations, as the biological interaction mechanism, the concept of harmful dose, and, in particular, the significance of the duration of exposure are unknown.
在特定情况下，由附近输电线在建筑物中产生的磁场通常很容易计算，尽管这些计算的准确性对源信息的质量很敏感。为了能够研究磁场暴露对公众健康的影响（例如癌症风险），有必要评估受影响人群的规模和暴露情况。关于公众暴露于高压输电线工频磁场的定量信息相对较少。本报告描述了芬兰全国范围内居民对110 kV、220 kV和400 kV输电线磁场的暴露情况，包括1989年线路总长度的90%。使用地理信息系统（GIS）来识别位于输电线附近的建筑物。在确定线路与建筑物之间的距离后，利用这些线路负荷电流的历史数据来计算磁场。然后通过计算机化的中央人口登记系统将居民的住宅磁场历史与居民联系起来。所获得的个人暴露数据也已用于一项关于输电线磁场暴露与癌症风险的全国性流行病学研究。描述了暴露评估方法以及110 kV、220 kV和400 kV输电线附近建筑物的数量、其年均磁场以及居民对这些线路磁场的个人暴露情况。我们发现，1989年有15,600名居民居住在由输电线导致的平均住宅磁场≥0.1微特斯拉的环境中。在1970 - 1989年期间，这些居民的数量增加了五倍。我们估计，0.3%的人口在其住宅中暴露于110 kV、220 kV和400 kV输电线产生的年均磁通密度高于0.1微特斯拉的环境中，而芬兰家庭中的背景磁通密度一般不会超过这一水平。因此，高压线路产生的磁场暴露问题仅涉及芬兰总人口中相对较小的一部分。然而，在实际的多源情况下，受影响人群的规模和暴露情况在一定程度上仍具有主观性，因为生物相互作用机制、有害剂量的概念，尤其是暴露持续时间的重要性尚不清楚。
