A previous study by the authors (Koteles et al. 2013) was replicated and the results should be confirmed. The ability of electrosensitive probands to sense exposure to a 50 Hz magnetic field should be investigated.
Subjects were divided into two groups: 1) subjects with self-reported electrosensitive complaints (n=49, experimental subjects), 2) subjects without electrosensitivity-related complaints (n=57, control subjects). Each participant was tested separately and should discriminate an exposure from a sham exposure of his hand in 20 consecutive test trials (10 exposure and 10 sham exposure trials in a random order) of 1 minute, respectively.
The study design was slightly modified in the present study in comparison to Koteles et al. 2013. In the original study, subjects described their sensings of the magnetic field only after the last test trial, what could have contributed to further bias. In the present study, subjects described their sensings after each individual test trial.
| Exposure | Parameters |
|---|---|
|
Exposure 1:
50 Hz
Exposure duration:
intermittent 10 times for 1 minute each
|
|
| Frequency | 50 Hz |
|---|---|
| Type | |
| Waveform | |
| Exposure duration | intermittent 10 times for 1 minute each |
| Exposure source | |
|---|---|
| Chamber | separated test chamber; power supply of the coils and the control switch were located in an adjacent room equipped with a sound-proof door; coolers of the power supply were operating during the whole experiment |
| Setup | two Helmholtz coils (inner diameter 42 cm, outer diameter 55 cm, made of 240 turns glaze-insulated copper wire (d=1.4 mm)) were placed at 21 cm distance to each other; a homogeneous magnetic field was produced between the coils; subjects put their right hand between the coils (coils below and above hand); exposure of other body parts was minimized by an iron plate positioned between the coil system and the subject; no changes in temperature were measurable (with a tolerance of 0.1°C) |
| Sham exposure | A sham exposure was conducted. |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| magnetic flux density | 500 µT | effective value | measured | - | at right hand during exposure |
| magnetic flux density | 1.14 µT | - | measured | - | at subject's head during exposure |
The detection rate of the magnetic field was not significantly different between electrosensitive subjects (group 1) and control subjects. However, both groups showed a slightly increased detection rate compared to mere chance, which was higher and significant in electrosensitive subjects.
There was no significant difference in the age and cooperation motivation between electrosensitive and control subjects, however, the expectations of perception, the tendency to perceive somatic sensations as intense or disturbing and health worries about radiation were significantly higher in electrosensitive subjects compared to control subjects.
The authors conclude that electrosensitive probands, exposed to a 50 Hz magnetic field, show a slight tendency to sense the magnetic field. This confirmed the results of Koteles et al. 2013. Moreover, results indicated that the reported symptoms correlated with the believed (perceived) presence of the magnetic field rather than with the actual presence of the magnetic field.
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