The influence of 50 Hz electric and magnetic fields on the extrasystoles of human heart.

This investigation studied the effect of 50 Hz electric and magnetic fields on the extrasystoles of human heart. The electrocardiograms (ECG) of 27 transmission-line workers and 26 male volunteers were recorded with a Holter monitor both in and outside the fields. The electric field strength varied from 0.14 to 10.21 kV/m and the magnetic flux density from 1.02 to 15.43 microT. The measurement period was from half an hour to a few hours. Analysis of the ECG recordings showed that extrasystoles were as frequent outside the field as in the field. In some cases a small decrease in heart rate was observed after field exposure, but it is possible that the changes in the pulse rate were caused by small changes of work load.