この研究は、IEI-EMFと自己申告した29人と対照者42人を対象とし、健康に関する質問票調査および磁界の感知に関する誘発試験を行った。まず、（1）ベースライン調査として、IEI-EMF の自己評点化とパーソナリティ検査票（SSAS、MHW-R、STAI-S）、症状の予期（これから行う実験中に不快な症状が現れると予期するか否かの質問）を行い、次に（2）感知実験として、50 Hz、0.5 mT 磁界（MF）の存在の感知実験（ヘルムホルツコイルの間に右手を入れた状態で、1分間のばく露・擬似ばく露を各10回ランダム試行）と不安度検査票（STAI-S）、最後に（3）体験した症状についての質問票検査を行った。心電図はベースライン値を記録後、感知実験中も記録を続けた。その結果、IEI-EMF群は対照群に比べ、偶然よりも高い確率で磁界を感知した；感知に関し正しい判断をした後の方が、間違った判断をした後に比べ、心拍変動パラメータが高いという特徴があった；実験中の症状を予期すると回答した人およびIEI-EMF群に属することは、その後のばく露実験で報告される症状の有意な予測子であった、などの所見を報告している。これまでの二重ブラインド試験の結果ではIEI-EMFの人は電磁界の存在を感知できないとされているのに対して、今回得られた結論が一致しないことに関して考察した他、MFが原因とされた症状は主として心理的原因によるものであるとも述べている。
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To study simultaneously the magnetic field detection ability and symptoms reported by people with idiopathic environmental intolerance attributed to electromagnetic fields (IEI-EMF). It was hypothesized that
1) people with IEI-EMF are able to detect a 50 Hz, 0.5 mT magnetic field to a given extent,
2) people with IEI-EMF adopt a lower decision criterion when deciding about the presence of the magnetic field,
3) people with IEI-EMF show an increased sympathetic activity during exposure,
4) people with IEI-EMF experience more unpleasant symptoms than the control group, and
5) some of these symptoms can be explained by previous expectations.
In addition, a relationship between IEI-EMF and the personality characteristics of somatosensory amplification and modern health worries was hypothesized.
29 individuals with self-reported idiopathic environmental intolerance attributed to electromagnetic fields and 42 control persons participated. The subjects had to attempt to detect the presence/absence of a magnetic field in 20 subsequent sessions. During the 20 detection sessions, the power supply of the coils was randomly enabled or disabled by the computer software (ten times "on" and ten times "off") for 60 s. After each session, participants were asked for the magnetic field perception. Exposure/sham exposure sessions were separated by 30 s recovery periods.
|ばく露時間||10 x 1 minute (in random order with sham exposure sessions for 1 minute)|
|ばく露装置の詳細||two solenoids (diameter: 42 cm) placed on a common axis spaced apart at a distance equal to their radii (21 cm); coils produced a vertical and homogenous field in the space between the coils; the coils were constructed of glaze-insulated copper wire (d = 1.4 mm) and had 240 turns; participants had to put their right hand between the coils; exposure of other body parts was prevented by an iron plate (dimensions: 800 mm x 500 mm x 2 mm) positioned between the coils and participants' body and by covering the coils with a special fabric containing copper fiber|
|Sham exposure||A sham exposure was conducted.|
Individuals with IEI-EMF were able to detect the presence of the 50 Hz magnetic field of 0.5 mT slightly better than by random guessing. while control groups' performance did not differ from chance. Experimental sessions followed by correct decisions were characterized by higher heart rate variability than periods followed by errors. Participants with IEI-EMF had a significantly lower decision criterion when they had to decide about the presence of the magnetic field. This means that they not only had slightly better detection abilities than controls, but they were also more prone to maximize the hit rate at the expense of false alarms in ambiguous cases. Additionally, participants with IEI-EMF exhibited more symptoms at the end of the experiment. IEI-EMF was closely related to concerns about possible harmful effects of electromagnetic exposure and to somatosensory amplification.
In conclusion, the detection of the magnetic field might be possible for people with IEI-EMF to some extent. Although increased sensibility to magnetic fields may play a role in the development of the IEI-EMF phenomenon, symptoms attributed to the magnetic field seem to be mainly of psychogenic origin.