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.
|Setup||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.