title: Heart rate variability (HRV) analysis in radio and TV broadcasting stations workers.
abstract: OBJECTIVE
  The aim of the study was to assess the mechanism of cardiovascular impairments in workers exposed to UHF-VHF radio frequency electromagnetic fields (EMF).
  
  
  METHODS
  Heart rate variability (HRV) was analysed using 512 normal heart beats registered at rest. The analysis concerned time-domain (STD R-R) and frequency-domain (VLF, LF, HF) parameters of HRV. Fifty nine workers (group I) with low-level and 12 workers (group II) with high-level exposure were examined. The mean age of the subjects was 47 ± 9 years and 41 ± 14 years, and mean exposure duration 19.1 ± 8.8 years and 13 ± 4 years, in groups I and II, respectively. The groups were divided according to: E(max), E(dose), E(mean) for frequencies UHF, VHF and UHF+VHF: The control group consisted of 42 non-exposed subjects, aged 49 ± 8 years. Statistical analysis comprised one-way analysis of variance, covariance analysis and logistic regression models.
  
  
  RESULTS
  In the exposed groups, the heart rate was higher than in the control one. Standard deviation of R-R intervals (STD R-R) was found to be significantly (p = 0.0285) lower in group I (42.5 ± 24.7 ms) compared to the control group (62.9 ± 53.5 ms). The risk of lowered STD R-R was significantly increased (OR = 2.37, p = 0.023) in group II. Both exposed groups presented significantly higher VLF and LF values than the control group (p = 0.005 and p = 0.0025, respectively). The EMF-exposed groups were characterised by the dominance of the sympathetic system (LF/HF 1.3 ± 0.35).
  
  
  CONCLUSIONS
  The results indicate that exposure to radiofrequency EMF may affect the neurovegetative regulation.
authors.affiliation: Department of Work Physiology and Ergonomics, Nofer Institute of Occupational Medicine, Łódź, Poland. alab@bg.p.lodz.pl
authors.forename: Alicja
authors.initials: A
authors.lastname: Bortkiewicz
authors.forename: Elżbieta
authors.initials: E
authors.lastname: Gadzicka
authors.forename: Wiesław
authors.initials: W
authors.lastname: Szymczak
authors.forename: Marek
authors.initials: M
authors.lastname: Zmyślony
mesh_terms: D000328:Adult; D000368:Aged; D004574:Electromagnetic Fields / Q000009:adverse effects*; D006339:Heart Rate / Q000528:radiation effects*; D006801:Humans; D008297:Male; D008872:Microwaves / Q000009:adverse effects*; D008875:Middle Aged; D016273:Occupational Exposure / Q000009:adverse effects*; D016272:Occupational Health; D011845:Radio; D013690:Television