Elmas2013.pdf

Article Toxicology and Industrial Health 1–7 © The Author(s) 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/0748233713498444 tih.sagepub.com

Effects of electromagnetic field exposure on the heart: a systematic review Onur Elmas

Abstract The use of electrical devices has gradually increased throughout the last century, and scientists have suggested that electromagnetic fields (EMF) generated by such devices may have harmful effects on living creatures. This work represents a systematic review of collective scholarly literature examining the effects of EMFs on the heart. Although most works describing effects of EMF exposure have been carried out using city electric frequencies (50–60 Hz), a consensus has not been reached about whether long- or short-term exposure to 50–60 Hz EMF negatively affects the heart. Studies have indicated that EMFs produced at cell-phone frequencies cause no-effect on the heart. Differences between results of studies may be due to a compensatory response developed by the body over time. At greater EMF strengths or shorter exposures, the ability of the body to develop compensation mechanisms is reduced and the potential for heart-related effects increases. It is noteworthy that diseases of heart tissues such as myocardial ischemia can also be successfully treated using EMF. Despite the substantial volume of data that has been collected on heart-related effects of EMFs, additional studies are needed at the cellular and molecular level to fully clarify the subject. Until the effects of EMF on heart tissue are more fully explored, electronic devices generating EMFs should be approached with caution. Keywords Electric field, magnetic field, electromagnetic field, heart, heart rate

Introduction Industrial improvement and economic expansion have enabled people to access a large number of electrical devices and equipment. Although these devices ease daily life, they also create electromagnetic fields (EMF) that are harmful for human health. According to scientific publications, this issue is becoming a critical health problem. The heart is the vital organ and is responsible for pumping blood into the tissues; however, because of its electrical stimulation, cardiac rhythm and cardiac cycle contraction can be affected by external stimuli. In this collective work, research articles describing the effects of EMF exposure on the heart are analyzed.

magnetic field occurs around the electric charge. Acceleration of charged objects changes the electric field and results in an electromagnetic wave (EMW) in the form of a sinusoidal curve. The EMF is distinct from charges and currents to which it relates; however, it can be defined as a wave movement carrying electromagnetic energy under specific conditions. The energy spreading in the form of EMW is called electromagnetic radiation. The source generating the wave determines the EMW frequency. EMWs are classified into types according to the frequency of the wave along a continuum of all possible frequencies of electromagnetic radiation called the electromagnetic spectrum (Table 1) (Wikipedia, 2012a).

Electromagnetic field

Sanliurfa Training and Research Hospital, Physiology Laboratory, Sanliurfa, Turkey

EMFs are caused by the movement of electric charges through space and are composed of electrical and magnetic fields. An electrical field arises around a static electric charge, but if a charge is moving, a

Corresponding author: Onur Elmas, Sanliurfa Training and Research Hospital, Physiology Laboratory, Sanliurfa 63000, Turkey. Email: [email protected]

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Table 1. The electromagnetic spectrum.a Class Extremely low freq. Super low freq.b Voice freq. Very low freq. Low freq. Medium freq. High freq. Very high freq. Ultra high freq. Super high freq. Extremely high freq. Far infrared Mid infrared Near Infrared Visible lightc Near ultraviolet Extreme ultraviolet Soft x-rays Hard x-rays Gamma rays

Frequency (f)

Wavelength (l)

Energy (E)

3 Hz–30 Hz 30 Hz–300 Hz 300 Hz–3 kHz 3 kHz–30 kHz 30 kHz–300 kHz 300 kHz–3 MHz 3 MHz–30 MHz 30 MHz–300 MHz 300 MHz–3 GHz 3 GHz–30 GHz 30 GHz–300 GHz 300 GHz–3 THz 3 THz–30 THz 30 THz–300 THz

100 Mm–10 Mm 10 Mm–1 Mm 1 Mm–100 km 100 km–10 km 10 km–1 km 1 km–100 m 100 m–10 m 10 m–1 m 1 m–1 dm 1 dm–1 cm 1 cm–1 mm 1 mm–100 mm 100 mm–10 mm 10 mm–1 mm

12.4 feV–124 feV 124 feV–1.24 peV 1.24 peV–12.4 peV 12.4 peV–124 peV 124 peV–1.24 neV 1.24 neV–12.4 neV 12.4 neV–124 neV 124 neV–1.24 meV 1.24 meV–12.4 meV 12.4 meV–124 meV 124 meV–1.24 meV 1.24 meV–12.4 meV 12.4 meV–124 meV 124 meV–1.24 eV

300 THz–3 PHz 3 PHz–30 PHz 30 PHz–3 EHz 3 EHz–30 EHz 30 EHz–300 EHz

1 mm–100 nm 100 nm–10 nm 10 nm–100 pm 100 pm–10 pm 10 pm–1 pm

1.24 eV–12.4 eV 12.4 eV–124 eV 124 eV–12.4 keV 12.4 keV–124 keV 124 keV–1.24 MeV

Freq: frequency; ELF: extremely low frequency. a Radio waves have frequencies from 3 kHz to as high as 300 GHz. Microwaves are radio waves with frequencies between 300 MHz and 300 GHz. b Another conflicting designation that includes this frequency range is ELF, which refers to frequencies from 3 to 300 Hz. (In this collected work, range of frequencies of 3–300 Hz is accepted as ELF). c The frequency range of the visible light is between 400 and 790 THz (Wikipedia, 2012a).

Electromagnetic radiation includes both wave and particle characteristics. When high-frequency EMWs encounter substances, they react as particles rather than waves. These particles are actually energy bunches and are referred to as a ‘‘quantum’’ or ‘‘photon.’’ A photon of low-frequency form of electromagnetic radiation has a low energy content and its particle qualities are not readily apparent. In contrast, the particle qualities of X-ray and gamma rays are much more explicit (Seker and Cerezci, 1997). Electrical fields are measured in terms of volts per meter (V/m) and electric flux density in terms of coulombs/square meter (C/m2), while magnetic fields are measured using amperes/meter (A/m) and magnetic flux density is quantified in terms of the tesla (T) (International Bureau of Weights and Measures (IBWM), 2008).

Effects of electromagnetic radiation on tissue The mechanism by which EMW affects human tissues is not entirely clear. When EMW energy collides with

a tissue surface, some is reflected and some is absorbed into the body. As EMW enters the tissue, its speed and wavelength changes depending upon the electrical properties of the tissue environment. EMW has two types of effects; thermal and nonthermal (Sanalan, 1999; Seker and Cerezci, 1991). Thermal effects result from increased molecular movement and friction caused by interaction between a substance and EMWs. Electromagnetic radiation causes damage by heating tissue through absorption of power intensity, or polarization, which is quantified as watt units per tissue surface area. The transfer of energy from EMWs to tissues occurs in the following steps: (1) electrical fields transfer kinetic energy to free electrons of any atom; (2) electrical fields affect electric dipoles and polarization of atoms and molecules; and (3) resulting tissue damage based on EMW energy, frequency, and incidence angle, electrical characteristics of biological material, amount of energy absorbed by the tissue, and exposure duration. The ‘‘dose’’ is defined as the energy absorbed in terms of tissue unit mass. Although the rate of energy absorption is important, the total amount of energy

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absorbed by living tissues is a critical factor. This is expressed as the relative absorbtion rate, defined as: Specific absorption rate (SAR) ¼ energy/(mass  time) ¼ Joules/kg(s) ¼ Watts/kg (Sanalan, 1999; Seker and Cerezci, 1991). Heat does not occur if the field strength of the wave is insufficient to produce substantial friction with the affected tissue. Charges like ions, molecular dipoles, or colloid particles are constantly moving within electrical fields. Under favorable conductance, dielectric constant, frequency, field strength conditions, and nonthermal effects can be more powerful than thermal effects depending on organism characteristics (Sanalan, 1999; Seker and Cerezci, 1991).

The heart: an inducible organ The heart is an organ consisting of a special type of striated muscle called cardiac muscle, which is capable of contracting to pump blood throughout body tissues through a special system of stimuli and conduction. Cardiac muscle cells are especially differentiated to transmit electrical stimuli, with myocardial cells enabling the heart to contract, sinoatrial and atrioventricular nodule cells creating the electrical stimulus, and endocardial cells spread the ventricles inward. These heart cells have four important physiological features: inducibility, contractibility, autonomy, and transmissibility (Koylu, 2001). Because of its inducibility, changes in the contraction and rhythm of the heart can result from external stimuli. It is possible for EMF to affect heart function by influencing these physiological features.

Effects of EMF on the heart Long-term occupational EMF exposure studies The first study published in the literature on this topic was conducted by Saznova (1967) on workers at electricity delivery centers fed by 50 Hz at 400–500 kV high-voltage lines. These authors observed that long-term exposure caused a decline in the subjects’ heart rates. However, Stopps and Janischewsky (1979) were unable to confirm the earlier results and suggested that there was no change in their subjects’ heart rates after conducting the similar studies on employees exposed to 50 Hz, at 400–500 kV electricity for more than 5 years. Moreover, Knave et al. (1979), Checcucci (1985), and Baroncelli et al. (1986) also conducted similar studies, and not all observed heart rate and electrocardiographic (ECG)

differences. Creasey and Goldberg (1993) reported arrhythmias and increased heart rates in a group of people working around electric trains and subjected to a 26 kV/m electrical field. Gurvich et al. (1995) concluded that extremely low-frequency (ELF)-EMF exposure at 2 kV/m in a work environment does not increase the risk of heart diseases.

Short-term EMF exposure studies ELF-EMF exposure studies. Silny (1981) did not report any changes in the ECGs of 100 subjects in his comprehensive study of 100 mT–80 kA/m EMF exposures between 5 Hz and 1 kHz. Maresh et al. (1988) described a decrease in the heart rates of participants performing exercise under 60 Hz, 9 kV/m, 16 A/m EMF exposure for 2 h. Korpinen et al. (1993) reported a decrease in heart rates after 1 hour of exposure to a 14-kV/m and 15.43 mT EMF; however, in another study (Korpinen and Partanen, 1994) conducted by the same authors, they did not observe any change after exposure to a 4.3-kV/m and 6.6-mT EMF. Graham et al. (1987) described a decrease in heart rate caused by an EMF in the 60-Hz band. In another study, the authors concluded that the effect depended on the specific magnetic field intensity (Graham et al., 1994). In that study, where subjects were exposed in three different milieus for 6 h (6 kV/m–10 mT, 9 kV/m–20 mT and 12 kV/m–30 mT), decreased heart rate was observed only in the group exposed to 9 kV/m–20 mT. No effects were observed in the other groups, interestingly, including the group exposed at a higher dose. This study supports the suggestion that the effect of EMF on the heart is related to the dose, although there may not be a correlation between the dose and the response. Ion channels, contraction proteins, or enzymes that contribute to heart contradiction and transmission may be affected only at specific frequencies and EMF doses. The differences in the findings of these studies may be explained by compensatory mechanisms that reduce EMF effects on the body. For example, the autonomic nervous system may prevent the effects of an EMF on the heart. A study conducted on humans by Sait et al. (1999), where heart rate variability (HRV) was used as an indicator of autonomic nervous system activity, supports this idea. At 50 Hz, 28 mT EMF exposure, the authors observed a decrease in the low-frequency HRV band that suggests an increase in sympathetic nervous system activity. The authors proposed that the increase in sympathetic nervous system

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activity compensated for the decrease in heart rate related to the EMF exposure. The same researchers attempted to induce more substantial alterations in the ECG using passive tilting to generate increased sympathetic neural control with minimized physiological disturbance, but they did not observe indications of autonomic compensation using this method (Sait et al., 2006). Another study by Tabor et al. (2004) generated EMF exposures using a 50-Hz commercial device for magnetotherapy, which produced a field of 500 mT at the center of the coil, 150–200 mT at the position of the human subject’s heart, and 20–30 mT at the position of the subject’s head. They reported a significant decrease in mean heart rate and a simultaneous increase in HRV. A study conducted by McNamee et al. (2010) involving exposure of human subjects to a 1.8 mT, 60 Hz, 15-min periodic, cumulative, and residual EMF reported a decrease in the heart rate as observed on the ECG. However, other studies found no effects from exposures to 16.7 Hz, 0.2 mT; 50–1000 Hz, 2–100 mT; 37 Hz, 80 mT; 50 Hz, 40–80 mT; and 60 Hz, 12.5 mT fields on the human heart (Ghione et al., 2004, 2005; Griefahn et al., 2001; Kurokawa et al., 2003; Nam et al., 2011). Jeong et al. (2005) have offered a different perspective based on the results from their evaluation of physiological responses in animals exposed to EMFs. In their study, two groups of rats were exposed to a 60-Hz, 2 mT EMF for 1 and 5 days, respectively. The authors observed a decrease in heart rates among the first group, but observed no changes in the second group. This study suggests that the heart may experience greater effects early during EMF exposure, but may later adjust because of compensatory effects in the body. In a study we conducted based on this hypothesis, we did not observe any immediate changes in ECG or heart rate under 50 Hz, 1 mT EMF exposure (Elmas et al., 2012). Other studies have analyzed effects of EMF on the heart in addition to heart rate and ECG. Gottwald et al. (2007) did not observe changes in the Heat shock protein 72 (HSP72) of heart cells from EMF exposures of 15–30 min in the range of 50 Hz, 2 mT–4 mT; however, George et al. (2008) reported improved myocardial contraction when modeling empirical ischemia reperfusion after induction of HSP70 protein by exposure to a 60-Hz, 8 mT EMF. Barzelai et al. (2009) suggested that a 15.95–16 Hz, 80 mT EMF could generate a substance with a prophylactic effect on heart injury after myocardial

infarction. Martı´nez-Sa´mano et al. (2010) observed an increase in free radicals, which was correlated with decreasing glutathione content in heart cells under a 2-h exposure to a 60-Hz, 2.4 mT ELF-EMF. Soker et al. (2011) did not observe any myofibrillar loss, dilation of smooth endoplasmic reticulum, mitochondrial swelling or cristalysis, intercalated disc degeneration, or apoptosis of nucleus resulting from a 14-day exposure to a 20-Hz, 0.25 mT EMF for 3 h/day. In a mouse study, Kiray et al. (2013) reported degenerative findings such as oxidative stress in myocardial cells and increased rates of apoptosis, mitochondrial degeneration, and waning in myofibrils after 4 h exposures to 3 mT, 50 Hz EMF per day for 2 months. EMF with microwave frequency exposure studies. Studies of effects on heart activity from exposure to ELFEMF are limited. Most of the published studies are related to the increasing use of cell phones over the last 15 years. Braune et al. (2002) did not report any changes in heart rate from exposure to a 900-MHz (pulse rate 217 Hz) and 2 W EMF. At a 900-MHz frequency, Wile´n et al. (2006) observed no change in heart rate after a 30-min exposure to a 1-W/kg EMF generated by cell phone use. Nam et al. (2006) reported similar results from an exposure to a 300mW/kg EMF and Johansson et al. (2008) reproduced the findings with a 1-W/kg exposure. Nevertheless, is has been recently concluded that cell phones do not affect heart rate according to a wide-ranging study of 700 subjects by Mortazavi et al. (2011). In another study of exposures at microwave frequencies, Wallace et al. (2012) reported no change in heart rate at 420 MHz, 10 mW/m. Other EMF exposure studies. Gaffey and Tenford (1981) conducted a study on rats exposed to a constant 2 T EMF over a 3-week period caused an increase in the T waves as observed on the ECG. These researchers also observed similar alterations with Macaca apes (Tenforde et al., 1983).

Discussion The aim of this collective work was to compile and review past studies analyzing the effects of EMFs on heart activity. The effects of EMFs on heart activity have primarily been evaluated through examination of heart rate in these studies. The formula for cardiac output is as follows: Cardiac output (milliliter

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per minute) ¼ heart rate (beats per minute)  stroke volume (milliliter per beat). This suggests that an external stimulus can affect the pump function of heart, changing the heart rate. Nevertheless, despite these studies, the effects of EMFs on the heart remain unclear. The frequency of the electricity and EMFs coming from distribution stations into our homes is approximately 50 Hz (in some countries it is 60 Hz). Because 50-Hz devices are used constantly, people are frequently exposed to ELF-EMFs of this magnitude in their daily lives. Studies of long-term and short-term exposures to ELF-EMFs of this strength are not in concurrence; however, results of studies carried out at microwave frequencies are more consistent but do not indicate any effects on the heart. The observed differences among these studies may result from changes induced by the body’s compensation mechanisms. When the body is affected by an external stimulus, intrinsic mechanisms are triggered to maintain homeostasis (the maintenance of relatively stable internal physiological conditions). If the effect of EMF is low enough to be compensated by these mechanisms, possible changes may not be observed in experiments. The heart may be influenced in the first moment of EMF exposure and at the following time, the body can compensate for the effects of an EMF. This would suggest that long-term exposures to EMF may result in increased resistance as compared to sporadic short-term exposures. There is not yet any consensus in these works about possible mechanisms by which effects of EMF exposure may occur. As suggested by the studies of Graham et al.(1994), it is also possible that only certain EMF doses and/or frequencies affect the heart, while other frequencies and/or doses produce no apparent effects. In this case, studies conducted using devices encountered in daily life at their average EMF values are more valuable than those experimentally applying very high or very low doses. Interestingly, research also suggests that diseases such as myocardial ischemia may be treated using EMF. This indicates that EMF may produce both harmful and beneficial effects, although there is insufficient data to clearly define all possible effects of EMF exposure. Additional studies are needed at the molecular and cellular level to better understand the effects of EMF exposure on the heart. In light of those publications that indicate possible effects of EMF on heart tissue, devices producing EMFs should be approached cautiously until the subject can be explored more completely.

Funding This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

References Baroncelli P, Battisti S, Checcucci A, Comba P, Grandolfo M, Serio A, et al. (1986) A health examination of railway high-voltage substation workers exposed to ELF electromagnetic fields. American Journal of Industrial Medicine 10: 45–55. Barzelai S, Dayan A, Feinberg MS, Holbova R, Laniado S and Scheinowitz M (2009) Electromagnetic field at 15.95-16 Hz is cardio protective following acute myocardial infarction. Annals of Biomedical Engineering 37(10): 2093–2104. Braune S, Riedel A, Schulte-Moting J and Raczek J (2002) Influence of a radiofrequency electromagnetic field on cardiovascular and hormonal parameters of the autonomic nervous system in healthy individuals. Radiation Research 158(3): 352–356. Checcucci A (1985) An epidemiological investigation of HV substation workers: study design and preliminary results. In: Grandolfo M, Michaelson SM and Rindi A (eds) Biological Effects and Dosimetry of Static and ELF Electromagnetic Fields. New York, NY: Plenum, pp. 557–569. Creasey WA, Goldberg RB (1993) Safety of High Speed Guided Ground Transportation Systems: Potential Health Effects of Low Frequency Electromagnetic Fields Due To Maglev and Other Electric Rail Systems. Washington, DC: US Department of Transportation, Federal Railroad Administration, Report DOT-FRA/ORD 93/31. Elmas O, Comlekci S and Koylu H (2012) Effects of shortterm exposure to powerline-frequency electromagnetic field on the electrical activity of the heart. Archives of Environmental and Occupational Health 67(2): 65–71. Gaffey CT, Tenforde TS (1981) Alterations in the rat electrocardiogram induced by stationary magnetic fields. Bioelectromagnetics 2: 357–370. George I, Geddis MS, Lill Z, Lin H, Gomez T, Blank M, et al. (2008) Myocardial function improved by electromagnetic field induction of stress protein hsp70. Journal of Cellular Physiology 216(3): 816–823. Ghione S, Del Seppia C, Mezzasalma L and Bonglio L (2005) Effects of 50 Hz electromagnetic fields on electroencephalographic alpha activity, dental pain threshold and cardiovascular parameters in humans. Neuroscience Letters 382: 112–117. Ghione S, Del Seppia C, Mezzasalma L, Emdin M and Luschi P (2004) Human head exposure to a 37 Hz electromagnetic field: effects on blood pressure,

Downloaded from tih.sagepub.com at UCSF LIBRARY & CKM on April 25, 2015

6

Toxicology and Industrial Health

somatosensory perception, and related parameters. Bioelectromagnetics 25(3): 167–175. Gottwald E, Sontag W, Lahni B and Weibezahn KF (2007) Expression of HSP72 after ELF-EMF exposure in three cell lines. Bioelectromagnetics 28(7): 509–518. Graham C, Cohen HD, Cook MR, Phelps J, Gerkovich MM and Fotopoulos SS (1987) A double blind evaluation of 60-Hz field effects on human performance, physiology, and subjective state. In: Anderson LE, Kelman BJ and Weigel RJ (eds) Interaction of Biological Systems With Static and ELF Electric and Magnetic Fields. Springfield, VA: National Technical Information Service, pp. 471–486. Report CONF-841041. Graham C, Cook MR, Cohen HD and Gerkovich MM (1994) Dose response study of human exposure to 60 Hz electric and magnetic fields. Bioelectromagnetics 15: 447–463. Griefahn B, K unemund C, Blaszkewicz Golka K, Mehnert P and Degen G (2001) Experiments on the effects of a continuous 16.7 Hz magnetic melatonin secretion, core body temperature, and heart rates in humans. Bioelectromagnetics 22: 581–588. Gurvich E, Rubtsova N and Novokhatskaya E (1995) Exposure to extremely low frequency electromagnetic fields as occupational risk factor. Epidemiology 6: S119. International Bureau of Weights and Measures (IBWM) (2008) The International System of Units (SI). Gaithersburg, MD: NIST Special Publication, pp. 4–14 Jeong JH, Kim JS and Lee BC (2005) Influence of exposure to electromagnetic field on the cardiovascular system. Autonomic and Autacoid Pharmacology 25: 17–23. Johansson A, Forsgren S, Stenberg B, Wile´n J, Kalezic N and Sandstro¨m M (2008) No effect of mobile phonelike RF exposure on patients with atopic dermatitis. Bioelectromagnetics 29(5): 353–362. Kiray A, Tayefi H, Kiray M, Bagriyanik HA, Pekcetin C, Ergur BU, et al. (2013) The effects of exposure to electromagnetic field on rat myocardium. Toxicology and Industrial Health 29: 418–425. Knave B, Gamberale F, Bergstro`em S, Birke E, Iregren A, Kolmodin Hedman B, et al. (1979) Long-term exposure to electric fields: a cross-sectional epidemiologic investigation of occupationally exposed workers in highvoltage substations. Scandinavian Journal of Work, Environment and Health 5: 115–125. Korpinen L, Partanen J and Uusitalo A (1993) The influence of 50 Hz electric and magnetic fields on the human heart. Bioelectromagnetics 14: 329–340. Korpinen L, Partanen J (1994) Influence of 50 Hz electric and magnetic fields on the pulse rate of human heart. Bioelectromagnetics 15:503–512.

Koylu H (2001) Fizyoloji dolasim solunum bosaltim. Isparta, Turkey: Tugra Matbaası, pp. 17–47. Kurokawa Y, Nitta H, Imai H and Kabuto M (2003) Can extremely low frequency alternating magnetic fields modulate heart rate or its variability in humans? Autonomic Neuroscience 105: 53–61. Maresh CM, Cook MR, Cohen HD, Graham C and Gunn WS (1988) Exercise testing in the evaluation of human responses to powerline frequency fields. Aviation, Space, and Environmental Medicine 59: 1139–1145. Martı´nez-Sa´mano J, Torres-Dura´n PV, Jua´rez-Oropeza MA, Elı´as-Vin˜as D and Verdugo-Dı´az L (2010) Effects of acute electromagnetic field exposure and movement restraint on antioxidant system in liver, heart, kidney and plasma of Wistar rats: a preliminary report. International Journal of Radiation Biology 86(12): 1088–1094. McNamee DA, Corbacio M and Weller JK (2010) The cardiovascular response to an acute 1800-microT, 60-Hz magnetic field exposure in humans. International Archives of Occupational and Environmental Health 83: 441–454. Mortazavi SM, Mahbudi A, Atefi M, Bagheri SH, Bahaedini N and Besharati A (2011) An old issue and a new look: electromagnetic hypersensitivity caused by radiations emitted by GSM mobile phones. Technology and Health Care 19(6): 435–443. Nam KC, Kim SW, Kim SC and Kim DW (2006) Effects of RF exposure of teenagers and adults by CDMA cellular phones. Bioelectromagnetics 27(7): 509–514. Nam KC, Choi JL, Kwon MK, Jang KH and Kim DW (2011) Physiological variables and subjective symptoms by 60 Hz magnetic field in EHS and non-EHS persons. Conference of the IEEE Engineering in Medicine and Biology Society 2011: 1925–1928. Sait ML, Wood AW and Kirsner RLG (2006) Effects of 50 Hz magnetic field exposure on human, heart rate variability with passive tilting. Physiological Measurement 27: 73–83. Sait ML, Wood AW and Sadafi HA (1999) A study of heart rate and heart rate variability in human subjects exposed to occupational levels of 50 Hz circularly polarised magnetic fields. Medical Engineering and Physics 21: 361–369. Sanalan Y (1999) Nu¨kleer Olmayan Radyasyonda Var. Bilis¸ im Toplumuna Giderken Elektromanyetik Kirlilik Etkileri Sempozyumu. Ankara, Turkey, 11 November 1999, pp. 1–4. Saznova TE (1967) Physiological effects ofwork in the vicinity of 400–500 kV outdoor installations. Report 46. Moscow: Institute of Labor Protection of All-Union Central Council of Trade Unions, pp. 34–49.

Downloaded from tih.sagepub.com at UCSF LIBRARY & CKM on April 25, 2015

Elmas

7

Seker SS, Cerezci O (1991) Elektromanyetik alanların biyolojik etkileri gu¨venlik standartları ve korunma yo¨ntemleri. Istanbul, Turkey: Bogazici Universitesi Yayinlari, pp. 8–12. Seker SS, Cerezci O (1997) Cevremizdeki Radyasyon ve Korunma Yontemleri. Istanbul, Turkey: Bogazici Universitesi Yayinlari, pp. 24–48 Silny J (1981) Influence of low-frequency magnetic field on the organism. In: Proceedings of the 4th Symposium on Electromagnetic Compatibility, 10–12 March 1981, Zurich, pp. 175–180. Soker S, Sert C, Deniz M, Tekmen I, Akkus M and Nergiz Y (2011) The effects of electromagnetic fields on the ultrastructure of heart. International Journal of Morphology 29(3): 960–964. Stopps GJ, Janischewsky W (1979) Epidemiological Study of Workers Maintaining HV Equipment and Transmission Lines in Ontario. Canadian Electrical Association Research Report, Montreal: Canadian Electrical Association. Tenforde TS, Gaffey CT, Moyer BR and Budinger TF (1983) Cardiovascular alterations in macaca monkeys

exposed to stationary magnetic fields: experimental observations and theoretical analysis. Bioelectromagnetics 4: 1–9. Tabor Z, Michalski J and Rokita E (2004) Influence of 50 Hz magnetic field on human heart rate variability: linear and nonlinear analysis. Bioelectromagnetics 25: 474–480. Wallace D, Eltiti S, Ridgewell A, Garner K, Russo R, Sepulveda F, et al. (2012) Cognitive and physiological responses in humans exposed to a TETRA base station signal in relation to perceived electromagnetic hypersensitivity. Bioelectromagnetics 33(1): 23–39. Wikipedia (2012a) Electromagnetic field. Available at: http://en.wikipedia.org/wiki/Electromagnetic_field (accessed 26 August 2012). Wikipedia (2012b) Electromagnetic spectrum. Available at: http://en.wikipedia.org/wiki/Electromagnetic_spectrum (accessed 26 August 2012). Wile´n J, Johansson A, Kalezic N, Lyskov E and Sandstro¨m M (2006) Psychophysiological tests and provocation of subjects with mobile phone related symptoms. Bioelectromagnetics 27(3): 204–214.

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