ABSTRACT
PURPOSE: Recent research by the authors on the effects of extremely low-frequency (ELF) magnetic field (MF) exposure on human heart rate (HR), heart rate variability (HRV), and skin blood perfusion found no cardiovascular effects of exposure to an 1,800-µT, 60-Hz MF. Research from our group using rats, however, has suggested a microcirculatory response to a 200-µT, 60-Hz MF exposure. The present pilot study investigated the effects of 1 h of exposure to a 200-µT, 60-Hz MF on the human circulation. Microcirculation (as skin blood perfusion) and HR were measured using laser Doppler flowmetry. Mean arterial pressure was monitored with a non-invasive blood pressure system. METHODS: Ten volunteers were recruited to partake in a counterbalanced, single-blinded study consisting of two testing sessions (real and sham exposure) administered on separate days. Each session included four consecutive measurement periods separated by rest, allowing assessment of cumulative and residual MF effects. RESULTS: A within-subjects analysis of variance did not reveal session by time period interactions for any of the parameters which would have been suggestive of a MF effect (p > 0.05). Perfusion, HR, and skin surface temperature decreased over the course of the experiment (p < 0.05). CONCLUSIONS: The MF used in this experiment did not affect perfusion, HR, or mean arterial pressure. Decreasing perfusion and HR trends over time were similar to our previous results and appear to be associated with a combination of inactivity (resulting in decreasing body temperatures) and reduced physiological arousal.
Subject(s)
Electromagnetic Fields/adverse effects , Fingers/radiation effects , Microcirculation/radiation effects , Skin/radiation effects , Adolescent , Adult , Female , Fingers/blood supply , Hemodynamics/radiation effects , Humans , Laser-Doppler Flowmetry , Male , Microcirculation/physiology , Middle Aged , Pilot Projects , Skin/blood supply , Young AdultABSTRACT
PURPOSE: Previously published literature has suggested an effect of extremely low-frequency (ELF) magnetic fields (MF) on human heart rate (HR) and heart rate variability (HRV). The combined response of the microcirculation and macrocirculation to ELF MF exposure has not previously been studied in humans. This study investigated the effects of 1-h exposure to an 1800-muT, 60-Hz MF on human microcirculation (represented in this study as skin blood perfusion), HR, low-frequency HRV, and high-frequency HRV. METHODS: Fifty-eight volunteers were recruited to partake in a double-blinded, counterbalanced study consisting of two testing sessions (real and sham) administered on separate days. Each session included four consecutive blocks of measurements, separated by 15-min rest periods, allowing measurement of cumulative and residual MF effects. Within subjects, ANOVA were conducted on each of the measured parameters. RESULTS: A decrease of skin blood perfusion and HR, and an increase of HRV were observed over blocks (p < 0.05). No session by block interactions were found for any of the cardiovascular parameters which would have suggested a MF effect (p > 0.05). A session by block interaction (p < 0.001) and a MF order effect (sham or real exposure first, p < 0.05) were observed for skin surface temperature. CONCLUSIONS: The MF used in this experiment did not affect cardiovascular parameters. Although an alternative explanation for why skin surface temperatures decreased in the sham and not in the real exposure condition is presented, the possibility of a MF effect cannot be excluded.
