Crasson Marion, Legros Jean-Jacques
Belgian BioElectroMagnetic Group, Psychoneuroendocrinology Unit, University of Liège, B-4000 Liège, Belgium.
Bioelectromagnetics. 2005 Apr;26(3):225-33. doi: 10.1002/bem.20070.
The purpose of this study was to reproduce and extend two earlier studies of the effects of human exposure to 50 Hz magnetic fields (MF). In a recent paper, we described results of two double-blind investigations performed to examine effects of 100 microT(rms) 50 Hz MF exposure on psychological parameters in the same group of healthy human volunteers. In each exposure session, at 1 week intervals, with sham, continuous, and intermittent (15 s ON/OFF cycles) MF conditions, mood ratings, performance measures, and electrophysiological measures were taken. In the first study, significant amplitude changes were observed in the event-related brain potentials (ERP) recorded during a dichotic listening task. In the second study, latency and reaction time (RT) slowing were seen on a visual discrimination task (P(300) paradigm). Although these results were little related to the number of parameters analysed, they indicate that low level 50 Hz MF might have a slight influence on ERP and RT under specific circumstances of sustained attention. Before concluding that moderately strong MF exposure can influence cognitive function, previous results should be replicated, using the same paradigms with another group of healthy volunteers. In the present study, 18 healthy subjects were exposed to three experimental sessions of 30 min each, given at 1 week intervals. The sessions consisted of continuous 100 microT(rms) 50 Hz MF exposure, sham condition, and bright light (5000 lux) exposure. The study was performed double-blind, with the exposure order counter-balanced. The data on mood, ERP, RT, and other performance measures did not show any differences among the sham exposure, light exposure, and MF exposure conditions. The results of this study do not support the hypothesis that extremely low frequency (ELF) MF exposure affects the brain's electrical activity or cognitive function at field strength (100 microT(rms)) similar to that found in very close proximity of some household and industrial electrical appliances and well in excess of the average MF strength (c. 0.1 microT) found in homes. The sensitivity of the experiment was possibly not sufficient to detect an effect at this relatively low MF, and larger sample sizes would be required in further studies.
本研究的目的是重现并扩展两项早期关于人类暴露于50赫兹磁场（MF）影响的研究。在最近一篇论文中，我们描述了两项双盲调查的结果，这些调查旨在研究100微特斯拉（均方根值）50赫兹MF暴露对同一组健康人类志愿者心理参数的影响。在每次暴露实验中，每隔1周进行一次，设置了假暴露、连续暴露和间歇暴露（15秒开/关循环）的MF条件，并进行了情绪评分、行为表现测量和电生理测量。在第一项研究中，在双耳分听任务期间记录的事件相关脑电位（ERP）中观察到了显著的振幅变化。在第二项研究中，在视觉辨别任务（P(300)范式）中发现潜伏期和反应时间（RT）延长。尽管这些结果与所分析参数的数量关系不大，但它们表明在持续注意力的特定情况下，低水平50赫兹MF可能对ERP和RT有轻微影响。在得出中等强度MF暴露会影响认知功能的结论之前，应该使用相同范式对另一组健康志愿者重复先前的结果。在本研究中，18名健康受试者每隔1周接受三次每次30分钟的实验。实验包括连续100微特斯拉（均方根值）50赫兹MF暴露、假暴露条件和强光（5000勒克斯）暴露。该研究采用双盲方式进行，暴露顺序进行了平衡处理。关于情绪、ERP、RT和其他行为表现测量的数据在假暴露、光暴露和MF暴露条件之间未显示出任何差异。本研究结果不支持以下假设：极低频（ELF）MF暴露在与某些家用和工业电器非常接近处发现的场强（100微特斯拉（均方根值））下，且远超过家庭中发现的平均MF强度（约0.1微特斯拉）时，会影响大脑的电活动或认知功能。该实验的灵敏度可能不足以检测到这种相对较低MF下的影响，进一步研究需要更大的样本量。
