Document Type: Original Paper
MS.c. in Occupational Hygiene , Tehran University of Medical Sciences, Tehran, Iran
Professor, Occupational Health Dept., Tehran University of Medical Sciences, Tehran, Iran
Assistant professor, Epidemiology and Biostatistics Dept.,Tehran University of Medical Sciences, Tehran, Iran
Assistant professor, School of Medicine, Army University of Medical Sciences, Tehran, Iran
Introduction: It has been reported that cardiovascular effects are among the possible health effects of being exposed to extremely low frequency electromagnetic fields (ELF EMSs).
Material and Methods: This study has been conducted to evaluate the long term effects of exposure to magnetic and electric fields on electrocardiogram signal changes. Nine power transmission posts having different voltages were chosen. The study was conducted in three stages. First, the intensity of root mean square (rms) of magnetic and electrical fields was assessed in different spots where the operators were spending more time. Then based on each operator’s work habits the time–weighted mean of intensity of rms in magnetic and electrical fields over a 12 hour period was estimated and used as an index for each operator. In the next step, 102 individuals were chosen among the operators according to their job and medical history. Each subject had an eletrocardiogram taken while being relaxed. The cardiograms were used to extract 5 parameters including number of heart bit, wave time of P, complex QRS, interval time of PR and QTC.
Using poly regression analysis method, the synchronized effects of independent variables such as age, job history, time–weighted mean of magnetic and electrical field on the extracted parameters of electrocardiogram signal was analyzed.
Results: The obtained results show that the synchronized effects of the variables can cause changes on PR and QTC interval of electrocardiogram signal. The most changes on PR and QTC interval are caused by the exposure to magnetic and electrical fields.
Discussion and Conclusion: Studying the effects of electromagnetic field on electrocardiogram signal is representative of effects of these fields on repolarization of cardiac cells. On the other hand, the heart rhythm and the number of heart bit are under the control of automatic system of central nervous system. Therefore, it is important to analyze electrocardiogram signal as well as heart rate variability signal in order to evaluate the field effects on the function of heart automatic system of central nervous system.