Department of Environmental Science, University of Eastern Finland, Kuopio, Finland.
Department of Epidemiology, University of California, Los Angeles, Los Angeles, California, USA.
J Expo Sci Environ Epidemiol. 2014 Jan-Feb;24(1):100-4. doi: 10.1038/jes.2013.54. Epub 2013 Sep 11.
Previous studies have shown that populations of multiapartment buildings with indoor transformer stations may serve as a basis for improved epidemiological studies on the relationship between childhood leukaemia and extremely-low-frequency (ELF) magnetic fields (MFs). This study investigated whether classification based on structural characteristics of the transformer stations would improve ELF MF exposure assessment. The data included MF measurements in apartments directly above transformer stations ("exposed" apartments) in 30 buildings in Finland, and reference apartments in the same buildings. Transformer structural characteristics (type and location of low-voltage conductors) were used to classify exposed apartments into high-exposure (HE) and intermediate-exposure (IE) categories. An exposure gradient was observed: both the time-average MF and time above a threshold (0.4 μT) were highest in the HE apartments and lowest in the reference apartments, showing a statistically significant trend. The differences between HE and IE apartments, however, were not statistically significant. A simulation exercise showed that the three-category classification did not perform better than a two-category classification (exposed and reference apartments) in detecting the existence of an increased risk. However, data on the structural characteristics of transformers is potentially useful for evaluating exposure-response relationship.
先前的研究表明，带有室内变压器站的多单元建筑群体可能成为改善儿童白血病与极低频（ELF）磁场（MF）之间关系的流行病学研究的基础。本研究调查了基于变压器站结构特征的分类是否会改善 ELF MF 暴露评估。该数据包括芬兰 30 栋建筑中直接位于变压器站上方的公寓（“暴露”公寓）以及同一建筑中的参考公寓的 MF 测量值。利用变压器的结构特征（低压导体的类型和位置）将暴露的公寓分为高暴露（HE）和中等暴露（IE）类别。观察到暴露梯度：无论是时间平均 MF 还是超过阈值（0.4 μT）的时间，HE 公寓中最高，参考公寓中最低，呈现出统计学上的显著趋势。然而，HE 公寓和 IE 公寓之间的差异在统计学上并不显著。模拟练习表明，在检测风险增加的存在方面，三类分类并不优于两类分类（暴露和参考公寓）。然而，变压器结构特征的数据对于评估暴露-反应关系可能是有用的。
