Effects of 45‐Hz magnetic fields on the functional state of the human brain

Abstract

The influence of sinusoidal 45-Hz magnetic fields on the brain functions of 20 volunteers was investigated in a double-blind study using spectral analysis of EEG and measurements of Omega potentials and reaction time (RT). The field strength was 1,000 A/m (1.26 mT) and the duration of exposure was 1 h. Ten volunteers were exposed to a continuous field and ten received an intermittent exposure (1 s on/l s off). Each person received one real and one sham exposure. One half of the volunteers got the real exposure first and the sham treatment after at least 24 h. For the rest, the sequence was inverse. The measurements of EEG, omega potentials and RT were performed before and after each exposure. Several statistically significant changes were observed, most of them after intermittent exposure. In the EEG, an increase of alpha (7.6-13.9 Hz) activity and a decrease of delta (1.5-3.9 Hz) activity were observed. Beta waves (14.2-20 Hz) increased in the frontal derivations as did the total power in occipital derivations. The mean and peak frequencies of EEG increased mainly in the frontal derivations. No direct effects on RT were seen. Learning to perform the RT test (decrease of RT in repeated trials), however, seemed to be affected by the exposure. The persons who received real exposure first learned more slowly than those who got sham exposure first. Further experiments are necessary to confirm the findings and for understanding the mechanisms of the effects.

Acute effects of 50 Hz magnetic field exposure on human visual task and cardiovascular performance

“…Prior research has indicated that EMF exposure might affect performance on relatively difficult tasks [see, e.g., Cook et al, 1992;Graham et al, 19941, but it does not seem to affect simple reaction time (RT) [see, e.g., Cook et al, 1992;Lyskov et al, 1993;Podd et al, 19951. In the present study, a two-alternative, forced-choice, visual duration-discrimination task with three levels of difficulty was used as the measure of performance, The purpose of using this particular task was twofold: 1) Previous research had shown that performance on a signal detection task was enhanced during EMF exposure significant results. Moreover, drawing conclusions from the research literature surveyed by Whittington and Podd is risky because of the adverse ratio of type I to type I1 errors created by low power levels.…”

“…The evidence for low-intensity, extremely-lowfrequency (ELF) electromagnetic field (EMF) effects on human behavior and physiology is slowly accumulating [see, e.g., Cook et al, 1992;Lyskov et al, 1993;Graham et al, 19941. Nevertheless, given the mixed results of the limited set of diverse experiments completed to date, it is difficult to say whether EMF exposure does or does not have effects on human task performance or physiological functioning.…”

Health risks of electric and magnetic fields caused by high-voltage systems in Finland

“…The studied magnetic flux density of 1.2 mT is extremely high, and in practice it is probably only met in high-voltage systems near air-core compensator reactors (1). Thus the findings of the study by Lyskov et a1 (21) currently have hardly any clinical significance.…”

“…From the viewpoint of occupational exposure and related safety aspects it was considered important to study the effects of low-frequency magnetic fields on the central nervous system. A study on the effects of the 45-Hz sinusoidal magnetic fields on brain functions was performed (21).…”

“…No conclusions could be drawn as to the hazardous effects of the fields on the central nervous system, but the interpretation of decreased activeness or relaxation of the central nervous system due to exposure to 45-Hz magnetic fields was referred to in the report by Lyskov et a1 (21).…”