[Evaluation of selected parameters of circulatory system function in various occupational groups exposed to high frequency electromagnetic fields. II. Electrocardiographic changes].

The effect of electromagnetic fields (EMF) on the circulatory and nervous systems has been the subject of great interest for many years, since electric impulses generated in these systems by outer electric and magnetic fields can theoretically disturb their functions. The only data on chronic effect of weak EMFs on the human body come from the studies carried out in the Soviet Union between the fifties and the seventies. In view of a growing number of persons exposed to EMF, there is an urgent need for verifying those data by means of modern diagnostic methods. That is the reason why our study of the EMF effect on the circulatory system has been initiated. It covered 71 workers at four AM broadcast stations, 40 workers at ten radio link stations and 42 workers at three radioservices. Workers' exposure to EMF was evaluated (see part I). Subjective and objective medical examinations were performed in all workers in order to assess their state of health, then resting electrocardiogram, Holter measurements, and high intensity ECG were taken, and variation in cardiac rhythm was analysed by a long-term recording of blood pressure. The results of the analysis of the questionnaire survey as well as the Holter and resting ECG examinations are presented. The study indicated that exposure to EMF in parameters found in AM broadcast station increased risk for electrographic disturbances (detected by means of resting ECG and a 24-hour Holter recording) by six times in comparison with that in radio link station workers not exposed to medium wave EMF. In radioservice workers this risk was twice as high as that in link station workers. It seems that in AM broadcast station workers, resting ECG should be complemented by a 24-hour Holter measurements, particularly, if workers complain of the circulatory system disturbances.