To conduct an neurophysiological examination of possible effects of exposure to a low-level 60 Hz magnetic field on persons with perceived electromagnetic hypersensitivity and controls ("groups") during rest and performance of a mental arithmetic task ("condition").
Twenty subjects (15 female and 5 male) with perceived electromagnetic hypersensitivity and twenty volunteers as control group took part in the study. The session lasted 40 minutes, divided into two ten minutes rest periods and two ten minutes periods of mathematical performance. Magnetic field and sham exposures were presented randomly in four conditions: Field-Rest, Sham-Rest, Field-Math, and Sham-Math.
| Exposure | Parameters |
|---|---|
|
Exposure 1:
50 Hz
Exposure duration:
10 min intermittent 15 s on/off
|
test sessions were divided into 4 conditions of 10 min each: i) EMF + rest ii) sham field + rest iii) EMF + mathematical test iv) sham + mathematical test
| Frequency | 50 Hz |
|---|---|
| Type | |
| Waveform | |
| Exposure duration | 10 min intermittent 15 s on/off |
| Exposure source |
|
|---|---|
| Setup | three square coils with 140 cm sides and 10 turns of 0.5 mm² insulated, tinned copper wire arranged around the armchair in which the subject was seated 1 m from a monitor; the lower coil was positioned at the floor, the second 80 cm and the third 160 cm above the floor |
| Sham exposure | A sham exposure was conducted. |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| magnetic flux density | 10 µT | effective value | measured | - | - |
No participants of both groups could reliably report the presence or absence of the magnetic field. Significant differences between subjects with perceived electrical hypersensitivity and controls (group factor without exposure) were observed in heart rate, heart rate variability, and electrodermal activity whereas the EEG characteristics showed no differences between the two groups. Analysis of the condition factor (rest versus arithmetic task) indicated main effects for heart rate, heart rate variability, electrodermal activity, and the alpha waves and theta waves of EEG. Magnetic field exposure did not affect autonomous system or EEG variables of either groups.
The authors concluded that there was no indication that the persons with perceived electrical hypersensitivity and controls were affected by low-level 60 Hz magnetic field exposure. However, differences in the baseline physiological variables were observed between both groups.
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