Neurovegetative Disturbances in Workers Exposed to 50 Hz Electromagnetic Fields

Abstract

Objectives: Since the circulatory and nervous systems are composed of electrically excitable tissues, it is plausible that they can be stimulated by electromagnetic fields (EMF). No clinical studies have as yet been carried out to explain whether and how occupational exposure to 50 Hz EMF can influence the neurovegetative regulation of the cardiovascular function. The present project was undertaken to assess the autonomic function in workers occupationally exposed to 50 Hz EMF, by analyzing the heart rate variability. Materials and Methods: The study group comprised 63 workers of switchyard substations, aged 22-67 years (39.2 ± 10.0 years), and the control group 42 workers of radio link stations, aged 20-68 years (40.7 ± 9.2 years), employed at workposts free from EMF exposure. The age range and employment duration in both groups did not differ significantly. To assess the neurovegetative regulation of the cardiac function, heart rate variability (HRV) analysis was made based on 512 normal heart beats recorded at rest. The analysis, performed using fast Fourier transformation, concerned the time-and frequency-domain HRV parameters. Power spectrum in the very low (VLF), low (LF) and high (HF) frequency bands was determined. Results: The relative risk of decreased HRV (STD R-R < 27 ms), calculated with use of a logistic regression model, was significantly higher in the exposed group than in controls (OR = 2.8). The VLF power spectrum was significantly higher in the exposed group and correlated with the exposure level. The percentage of subjects with dominant sympathetic function (LF/HF>1) was significantly higher in the study group than in controls (65% vs. 47%). Conclusions: It was concluded that occupational exposure to 50 Hz EMF could influence the neurovegetative regulation of the cardiovascular system.

Heart rate variability (HRV) analysis in radio and TV broadcasting stations workers

“…Neurovegetative disturbances were also found in our earlier study in workers exposed to 160 MHz electromagnetic fields. In this group, the HRV changes were reflected by the power spectrum in the LF and VLF bands and correlated with those in arterial blood pressure [22]. As regards the workers exposed to medium frequency EMF, statistically significant negative correlation was found between the maximum intensity of EMF and HF power spectrum [4].…”

“…Moreover, the results of these studies cannot be extrapolated to humans. The research team from the Nofer Institute of Occupational Medicine, Łódź, Poland, has continued for a couple of years projects regarding cardiovascular function and its neurovegetative regulation in workers occupationally exposed to different frequency EMF: at switchyard substations (50 Hz) [2,3], at medium frequency (MF) broadcasting stations (1 MHz) [4], at high frequency (HF) communication centres (10-50 MHz) and radioservices (160 MHz) [5,6]. The resultant findings indicate that EMF exposure induces various cardiovascular abnormalities, of the types depending on EMF frequency.…”

Description of a large-scale study design to assess work-stress-disease associations for cardiovascular disease

“…The trade-off is that if Stages 2 to 4 (above in Section III) hypotheses are to be tested, many forms of resource-intensive bio-monitoring must be employed, which may limit the size of the study population. [38][39][40][41].…”

“…A major message of Whitehall then became the separate effects of low control on CVD. Single occupation studies lack sufficient psychosocial exposure variance to allow testing of main or interactive effects of psychosocial factors, making it difficult to generalize typical physical exposure-based occupational health findings (above noted EMF studies by Bortkiewicz et al and Szmigielski et al) [38][39][40][41]. The adverse effect of a limited range of job characteristic variance was also clearly illuminated in the Collins, Karasek, and Costas study [29].…”

“…The findings obtained by Bortkiewicz et al indicated that exposure to electromagnetic fields may induce cardiovascular abnormalities: ventricular arrhythmia, elevated arterial blood pressure and impaired day-night BP regulation. These abnormalities correlated with HRV disturbances, mainly with the decrease of parasympathetic activity and with the level of exposure [38][39][40][41]. While these studies demonstrate the impact of EMF on cardiovascular deregulation, they could not simultaneously control for potential psychosocial environmental exposures due to the limited psychosocial environmental exposure variance available with just a single occupational group.…”