Provocation study of persons with perceived electrical hypersensitivity and controls using magnetic field exposure and recording of electrophysiological characteristics

The aim of the present study was to investigate possible neurophysiological effects of intermittent 15 sec on/off cycle, 60 Hz, 10 muT magnetic field exposure on patients with perceived "electromagnetic hypersensitivity" (EHS ), and control subjects during rest and performance of a mental arithmetic task. Twenty participants (15 female, 5 male, 31-60 years old, mean 45.8 +/ - 0.7 years) were invited from the group of EHS patients. Twenty volunteers (15 female, 5 male, 31-59 years old, mean 45.0 +/- 0.7 years) served as a control group. The test protocol consisted of a set of examinations: EEG, v isual evoked potentials, electrodermal activity, ECG, and blood pressure. T he total duration of the test was 40 min, divided into two 10 min rest peri ods and two 10 min periods of mathematical performance. Magnetic field and sham exposures were presented randomly during these periods, resulting in f our different conditions: Field-Rest, Sham-Rest, Field-Math, and Sham-Math. The data showed significant main effects of the Group factor (EHS vs. cont rol subjects) on heart rate (F-1,F-80=20.6; P <0.01), heart rate spectrum r atio (F-1,F-80=9.5; P=0.02), and electrodermal activity (F-1,F-76 = 4.2; P = 0.04), whereas EEG characteristics did not differ between groups. The Con dition factor (mathematical task vs. relaxed) showed main effects for heart rate (F-1,F-80 = 14.8; P < 0.01), heart rate spectrum ratio (F-1,F-80 = 7. 8; P = 0.06), electrodermal activity (F-1,F-76 = 56.8; P < 0.01), and alpha and theta spectral bands of EEG. Magnetic field exposure did not affect au tonomous system or electroencephalographic variables of either group. These data do not indicate that EHS patients or control are affected by low-leve l 60 Hz magnetic field exposure. However, persons reporting EHS differed fr om the control subjects in baseline values of investigated physiological ch aracteristics. Perhaps EHS patients have a rather distinctive physiological predisposition to sensitivity to physical and psychosocial environmental s tressors. (C) 2001 Wiley-Liss, Inc.