UCLA School of Public Health, Department of Epidemiology, Los Angeles, California 90095-1772, USA.
J Expo Sci Environ Epidemiol. 2011 Nov-Dec;21(6):625-33. doi: 10.1038/jes.2010.38. Epub 2010 Jul 7.
For 30 years, there have been suggestions that extremely low frequency magnetic fields such as those are produced by electric power systems may be associated with elevated risks of childhood leukemia. These suggestions are driven by epidemiological evidence, and it has been common to characterize that evidence as showing a threshold effect, with no increase in risk below a threshold, often 0.3 or 0.4 μT, and a constant risk above it. Such a threshold would, however, be biologically unlikely. We tested alternative dose-response relationships quantitatively. We obtained five exposure data sets, applied several candidate dose-response relationships to each one, and performed a regression analysis to see how well they fit each of the three epidemiological data sets. Threshold dose-response relationships performed only moderately. Linear relationships were generally even poorer. The fit was improved by adding quadratic terms or performing non-linear regression. There are limitations in our analysis, stemming from the available data, but addressing this issue in a data-based, quantitative manner should improve understanding, allow better calculations to be made of attributable numbers, and hence ultimately inform public policy making.
三十年来，一直有研究表明，电力系统产生的极低频磁场（例如那些磁场）可能与儿童白血病风险升高有关。这些研究结果是基于流行病学证据得出的，并且通常将这些证据描述为存在阈值效应，即在阈值以下，风险不会增加，通常为 0.3 或 0.4 μT，而在阈值以上则风险保持不变。然而，这样的阈值在生物学上是不太可能的。我们定量检验了替代剂量-反应关系。我们获得了五个暴露数据集，将几种候选剂量-反应关系应用于每一个数据集，并进行回归分析，以了解它们对三个流行病学数据集的拟合程度。阈值剂量-反应关系的拟合效果仅为中等。线性关系通常更差。通过添加二次项或进行非线性回归，可以提高拟合度。我们的分析存在一些局限性，这些局限性源于现有数据，但以基于数据的定量方式解决这个问题，应该能够增进理解，更好地计算归因数字，从而最终为公共政策制定提供信息。
