Dose response study of human exposure to 60 Hz electric and magnetic fields

Abstract

This human exposure study examined the relationship between field strength and biological response and tested whether the exposure levels at which the greatest effects occur differ for different endpoints. Three matched groups of 18 men each participated in two 6 h exposure test sessions. All subjects were sham exposed in one session. In the other session, each group of subjects was exposed at a different level of combined electric and magnetic field strength (low group:6 kV/m, 10 microT; medium group:9 kV/m, 20 microT; and high group: 12 kV/m, 30 microT). The study was performed double blind, with exposure order counterbalanced. Significant slowing of heart rate, as well as alternations in the latency and amplitude of event-related brain potential measures derived from the electro encephalogram (EEG), occurred in the group exposed to the 9 kV/m, 20 microT combined field (medium group). Exposure at the other field strength levels had no influence on cardiac measures and differential effects on EEG activity. Significant decrements in reaction time and in performance accuracy on a time estimation task were observed only in the low group. These results provide support for the hypothesis that humans may be more responsive to some combinations or levels of field strength than to others and that such differences in responsivity may depend, in part, on the endpoint of interest.

Cardiac Autonomic Control Mechanisms in Power-Frequency Magnetic Fields: A Multistudy Analysis

“…In study E the volunteers were exposed only to the continuous magnetic field, and in studies F and G they were exposed to both intermittent and continuous magnetic fields. The decision to emphasize intermittent field exposure and to use circularly polarized fields was based on previous research indicating that such exposure is associated with alterations in human physiology (10,19,20) and also on rodent research reporting that circularly polarized fields are more effective than linearly polarized fields in reducing nocturnal concentrations of the pineal hormone melatonin (21).…”

Neurovegetative Disturbances in Workers Exposed to 50 Hz Electromagnetic Fields

“…Human volunteer studies provide contradictory findings. Some have indicated bradycardia as one of the cardiac effects of exposure to weak power frequency EMF [2][3][4]; whereas others do not report any significant cardiovascular abnormalities [5][6][7][8]. In some studies, dysfunction of the autonomic nervous system [9], arterial blood pressure (hypo-or hypertension), heart rhythm (brady-or tachycardia) disturbances [10,11] and an increased neuromuscular activity [12] were found in workers occupationally exposed to 50/60 Hz EMF.…”

ECG Changes in Humans Exposed to 50 Hz Magnetic Fields

“…The T-wave was affected rather than other components of ECG, since blood flows through the aorta during the period when ventricular repolarization is taking place. The increased T-wave voltage was unrelated to the electrical activity of the pacemaker area of the heart and the ECG change was simply a reflection of the coincident "magnetohydrodynamic" voltage generated by the blood flow in the presence of the applied magnetic field.Investigators at one laboratory (Midwest Research Institute, Kansas City, Missouri., USA) have studied the effects of EMFs on the heart rate in humans for several years 1,2) . According to their results, exposure to 60 Hz electric and magnetic fields resulted in a significant decrease of the heart rate.…”