8

HUMAN LABORATORY AND CLINICAL EVIDENCE OF EFFECTS OF ELECTROMAGNETIC FIELDS

The acute effects of electric and magnetic fields and currents on human volunteers have been extensively studied in the laboratory. End points that have been examined include perception,1,2,3,4,5,6,7 behavior,8,9,10,11 nervous system function,12,13 endocrine function,14 blood composition,15 mood,16,17 and bone growth.18,19,20,21,22,23,24 Except for studies of the perception of contact currents, however, there have been no laboratory studies of the effects of low-frequency (LF) fields or currents on humans. Most of the laboratory evidence involves exposures at extremely low frequency (ELF), with fewer studies being reported at microwave frequencies. The relevance of this research to the possible effects of GWEN fields is therefore uncertain (see section on Frequency Extrapolation). A body of clinical research on the effects of continuous-wave (CW) LF fields on bone stimulation might be of greater relevance to GWEN exposures. This chapter briefly describes the human laboratory and clinical evidence. More detailed reviews are available elsewhere.25,26,27,28,29

CUTANEOUS PERCEPTION

Cutaneous perception is one of the best-studied of the effects of electromagnetic fields (EMFs) on humans. At extremely low frequencies, one perceives the presence of electric fields through stimulation of vibration or pressure sensors. Studies of electric-field perception at 50-60 Hz have yielded thresholds of 2-30 kV/m, depending on the subject, posture, and humidity.6,7,30 The threshold for cutaneous perception of ELF magnetic fields is unknown, but Graham et al.6 report that seated subjects were unable to detect the presence of 60-Hz magnetic fields up to 32 A/m (= 400 mG = 40 µT).

The detection of LF currents flowing through the skin is reviewed in Chapter 3. Such currents can arise from contacts with ungrounded metal structures near GWEN relay nodes (RNs). Briefly, the sensation of LF currents passed through either a fingertip or a gripped contact is one of warmth, with perception thresholds of 20-300 mA, depending on the subject and type of contact.4,5Chapter 3 also shows that currents arising from contact with vehicles, fences, and other large conducting objects that might be in the vicinity of a GWEN RN are below the threshold of perception for any type of contact. Cutaneous-perception thresholds for incident EMFs at ultra-high frequencies (UHF) comparable to the GWEN transmitters (225-400 MHz) have not been measured, but, because of differences in penetration depth, are expected to be somewhat above the 15- to 44 mW/cm2 threshold measured by Justesen for 2,450-MHz fields applied to the forearm.11 That is roughly 10,000 times the UHF power density at the boundary of GWEN RNs.



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ASSESSMENT OF THE POSSIBLE HEALTH EFFECTS OF GROUND WAVE EMERGENCY NETWORK 8 HUMAN LABORATORY AND CLINICAL EVIDENCE OF EFFECTS OF ELECTROMAGNETIC FIELDS The acute effects of electric and magnetic fields and currents on human volunteers have been extensively studied in the laboratory. End points that have been examined include perception,1, 2, 3, 4, 5, 6, 7 behavior,8, 9, 10, 11 nervous system function,12, 13 endocrine function,14 blood composition,15 mood,16, 17 and bone growth.18, 19, 20, 21, 22, 23, 24 Except for studies of the perception of contact currents, however, there have been no laboratory studies of the effects of low-frequency (LF) fields or currents on humans. Most of the laboratory evidence involves exposures at extremely low frequency (ELF), with fewer studies being reported at microwave frequencies. The relevance of this research to the possible effects of GWEN fields is therefore uncertain (see section on Frequency Extrapolation). A body of clinical research on the effects of continuous-wave (CW) LF fields on bone stimulation might be of greater relevance to GWEN exposures. This chapter briefly describes the human laboratory and clinical evidence. More detailed reviews are available elsewhere.25, 26, 27, 28, 29 CUTANEOUS PERCEPTION Cutaneous perception is one of the best-studied of the effects of electromagnetic fields (EMFs) on humans. At extremely low frequencies, one perceives the presence of electric fields through stimulation of vibration or pressure sensors. Studies of electric-field perception at 50-60 Hz have yielded thresholds of 2-30 kV/m, depending on the subject, posture, and humidity.6, 7, 30 The threshold for cutaneous perception of ELF magnetic fields is unknown, but Graham et al.6 report that seated subjects were unable to detect the presence of 60-Hz magnetic fields up to 32 A/m (= 400 mG = 40 µT). The detection of LF currents flowing through the skin is reviewed in Chapter 3. Such currents can arise from contacts with ungrounded metal structures near GWEN relay nodes (RNs). Briefly, the sensation of LF currents passed through either a fingertip or a gripped contact is one of warmth, with perception thresholds of 20-300 mA, depending on the subject and type of contact.4, 5 Chapter 3 also shows that currents arising from contact with vehicles, fences, and other large conducting objects that might be in the vicinity of a GWEN RN are below the threshold of perception for any type of contact. Cutaneous-perception thresholds for incident EMFs at ultra-high frequencies (UHF) comparable to the GWEN transmitters (225-400 MHz) have not been measured, but, because of differences in penetration depth, are expected to be somewhat above the 15- to 44 mW/cm2 threshold measured by Justesen for 2,450-MHz fields applied to the forearm.11 That is roughly 10,000 times the UHF power density at the boundary of GWEN RNs.

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ASSESSMENT OF THE POSSIBLE HEALTH EFFECTS OF GROUND WAVE EMERGENCY NETWORK PHOSPHENES ELF currents passing through the retina cause the perception of images called phosphenes. The effect is noted only in the ELF band and can be induced by either direct coupling or induction. Thresholds for magnetically-induced phosphenes range from 8 mT at 20 Hz to 20 mT at 60 Hz.12, 31, 32, 33 The minimum retinal current density required to produce the effect is less than 1 µA/cm2 at 20 Hz. Although GWEN LF and UHF fields can induce current densities up to 1 µA/cm2, GWEN frequencies are too high for phosphenes to be observed. PACEMAKER INTERFERENCE Many older models of cardiac pacemakers are susceptible to electromagnetic interference. The threshold of susceptibility depends on the device design and on the frequency and amplitude of the interference. Measurements with a variety of pacemakers available around 1975, for instance, showed interference thresholds as low as 6 V/m for pulsed fields at 450 MHz.34 Newer pacemakers incorporate rejection circuitry that makes them immune to RF interference. Because there is a finite lifetime for pacemakers, most of the older models have been replaced by the new types. MICROWAVE AUDITORY EFFECT Humans exposed to rectangular microwave pulses of microsecond duration perceive a sound if the energy flux of the pulse is high enough (about 40 µJ/cm2).13 The phenomenon has been shown to arise from an acoustic wave generated in the head by the small but rapid thermoelastic expansion of tissue caused by microwave-energy absorption. The energy flux from GWEN LF or UHF emissions is much too small to elicit this auditory effect. CIRCADIAN RHYTHMS Wever35, 36, 37 used a specially constructed living environment with no time cues to demonstrate that human circadian periods are lengthened by an average of 20 min when the living space is shielded against natural electric and magnetic fields. Introduction of a weak 2.5-V/m, 10-Hz square-wave electric field into the shielded environment was found to shorten circadian periods by 1.3 h relative to the field-free condition. The same square-wave field was also found to weakly entrain free-running circadian rhythms. Sinusoidal electric-field exposures of the same frequency and intensity were not as effective as the square-wave fields. The experiments have not been repeated elsewhere.

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ASSESSMENT OF THE POSSIBLE HEALTH EFFECTS OF GROUND WAVE EMERGENCY NETWORK BRAIN-EVOKED POTENTIALS In an extensive series of experiments, Graham et al.14 repeatedly observed an influence of combined 60-Hz electric and magnetic fields on the late components of the auditory-evoked potential. The effects were observed for both continuous and intermittent exposures and were more pronounced at combined fields of 9 kV/m and 20 µT than at higher or lower combined-field strengths. Because only late components are affected, Graham and colleagues conclude that the effect is on the cognitive process of stimulus evaluation and not on overall neural conduction velocity. Alterations in visually-evoked potentials (VEPs) were also reported by Silny38 to occur in response to sinusoidal 50-Hz magnetic fields with flux densities exceeding 5 mT. The change in VEP was characterized by a reversal of polarity and a decrease in the amplitude of the three major evoked potentials. The effects were observed within 3 min after onset of the magnetic-field exposure, and the VEP returned to normal by approximately 30-70 min after termination of the exposure. HEART RATE Lowering of heart rate has been often, but not universally, observed in experiments involving human exposure to ELF electric fields, magnetic fields, and injected currents.14 Table 8-1 lists relevant findings. The studies reporting heart-rate decreases generally characterize them as temporary, noncumulative, and within the range of normal physiologic variation. Extrapolation of the findings to GWEN LF and UHF exposures is difficult. The current density induced by LF exposures at the GWEN site boundary is hundreds of times larger than the ELF current densities associated with changes in heart rate (0.1 µA/cm2). As the discussion in Chapter 3 points out, however, the sensitivity of muscle and nerve tissue at LF and UHF is likely to be much lower than that at ELF. Although experiments on the effects of exposure to radiofrequency (RF) fields on human heart rate are lacking, evidence from animal studies shows no acute effects of RF irradiation on heart rate in situ26 (also see Chapter 6). Long-term effects of small RF exposure on cardiovascular function remain largely unstudied. REACTION TIME The effects of ELF electric fields on human reaction time in response to auditory or visual stimuli have been extensively studied, but the results have been inconsistent.14, 27 Increased auditory or visual reaction times have been noted at thresholds ranging from 1-2 V/m in a 3-Hz field8 to 10 kV/m in a 50-Hz field.45 Decreased visual reaction times were found by Hauf46 in 50-Hz fields of 1 and 15 kV/m, but were not verified by later experiments in the same laboratory.41, 47

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ASSESSMENT OF THE POSSIBLE HEALTH EFFECTS OF GROUND WAVE EMERGENCY NETWORK TABLE 8-1 Effects of ELF Fields and Currents on Human Heart Rate Exposure Effect on heart rate Reference Occupational exposure in 50-Hz switchyards Decrease 39 50-Hz electric field, 4 kV/m Decrease 40 50-Hz injected current, 2 mA Decrease 41 50-Hz electric field, 10-15 kV/m Decrease 42 Combined 60-Hz electric and magnetic fields up to 15 kV/m and 300 mG Decrease 14 50-Hz electric field up to 20 kV/m Not significant 43, 46 Occupational exposure from high voltage transmission lines Not significant 44 50-Hz injected current, 0.5 mA Not significant 10 Gamberale and colleagues44 found that a normal increase in reaction time throughout the day was smaller for high-voltage linemen when they were working on energized lines than when they were working on de-energized lines. In an extensive series of experiments involving exposures to 60-Hz electric fields up to 12 kV/m and 60-Hz magnetic fields up to 30 µT (300 mG), Graham et al. found no consistent effect of field exposures on reaction times.14

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ASSESSMENT OF THE POSSIBLE HEALTH EFFECTS OF GROUND WAVE EMERGENCY NETWORK MOOD AND COGNITIVE FUNCTION Stollery16 measured the acute effects of 50-Hz current on mood and verbal reasoning. Subjects were exposed or sham-exposed to a 36-kV/m field for 5.5 h on each of 2 days. Five tests of mood and verbal reasoning were administered throughout the experiment. Exposure-related effects were noted on the second day in stress level, as measured by a mood-adjective checklist, and in response times in tests of syntactic reasoning. In a second series of experiments involving an identical exposure regimen, Stollery measured the effects of 50-Hz current on vigilance and concentration.9 No effects on those end points were observed, and the suggestion of exposure-induced stress raised by the earlier study was not confirmed. In their investigation of high-voltage linemen doing simulated line inspections, Gamberale and colleagues found no effect on wakefulness or stress, as measured by a mood-adjective questionnaire.44 They also observed no effects on vigilance, perceptional speed, or short-term memory. BLOOD COMPOSITION Human laboratory studies examining field effects on blood composition are limited to the ELF range. Sander and colleagues48 exposed volunteers to 50-Hz electric fields of 10-20 kV/m for 6-22 h/d for a week and found no effects of exposure on the concentrations of 33 constituents of blood. Gamberale44 found no effects on serum concentrations of seven hormones in linesmen performing simulated inspections of a 400-kV transmission line. In an experiment involving 11 subjects, Beischer, et al.15 found increases in serum triglycerides among subjects exposed to a 1-G (100-µT) 45-Hz magnetic field. In contrast, Rupilius47 found no difference in triglyceride concentrations between a control group and subjects exposed for 3 h to combined 3-G (300-µT) and 20-kV/m 50-Hz fields. BONE REPAIR AND GROWTH STIMULATION Induced or injected currents have been widely used to treat recalcitrant nonunions of fractured bone by stimulating bone growth. Sinusoidal, DC, and pulsed currents have each produced some measure of success24, 49 Brighton et al. have observed enhancements in bone-fracture repair with 60-kHz CW currents.19, 20, 21, 22 The threshold electric field in bone tissue19, 50 needed to produce the 60-kHz effects ranges from 5 to 20 mV/cm, corresponding to a range of induced current of 2.5-10 µA/cm2. That is comparable with the average LF electric field and current density induced in bone tissue of a person standing at the boundary of a GWEN RN site. There are few data on the frequency dependence of the bone-healing effects reported by Brighton and colleagues. One study of healing of rabbit fibula showed significant field-induced

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ASSESSMENT OF THE POSSIBLE HEALTH EFFECTS OF GROUND WAVE EMERGENCY NETWORK healing at 60 kHz, but not at 10 kHz or 250 kHz with induced currents of the same intensity.20 Limited evidence of the role of duty cycle in the bone-healing effect at 60 kHz shows no clear pattern. Field-induced enhancements in thymidine incorporation in vitro were found at duty cycles as short as 0.25% 22 and 0.5%,23 but disuse osteoporosis in vivo was reversed only by duty cycles greater than about 10%.21 Although studies in different biological systems have shown that 60-kHz tissue fields around 2 V/m can evoke measurable biological effects, there is little evidence with which to judge the strength of such effects at GWEN LF frequencies and duty cycles. If GWEN LF fields can induce biological responses in bone tissue, evidence is too scant to conclude whether the responses would be beneficial or harmful. CONCLUSIONS As with the animal and in vitro evidence reviewed by the committee, few human laboratory data are directly relevant to GWEN-related exposures. However, the many laboratory studies of human exposure to ELF fields have not identified any deleterious acute effects, although data on chronic exposure are lacking. Studies demonstrating bone growth induced by kilohertz fields are interesting, but there is no evidence of effects of such exposures on healthy tissues.

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ASSESSMENT OF THE POSSIBLE HEALTH EFFECTS OF GROUND WAVE EMERGENCY NETWORK REFERENCES 1. Tucker, R. D., and O. H. Schmitt. 1978. Tests for human perception of 60 Hz moderate strength magnetic fields . IEEE Transactions on Biomedical Engineering, BME 25(6) : 509-518. 2. Dalziel, C. F., and T. H. Mansfield. 1950. Effect of frequency on perception currents. AIEE Transactions, Vol 68, Part II : 1162-1168. 3. Dalziel, C. F. 1954. The threshold of perception currents. AIEE Transactions on Power Apparatus and Systems, 73 : 990-996. 4. Chatterjee, I., D. Wu, and O. P. Gandhi. 1986. Human body impedance and threshold currents for perception and pain for contact hazard analysis in the VLF-MF band. IEEE Transactions on Biomedical Engineering, 33(5) : 486-494. 5. Gandhi, O. P., I. Chatterjee, D. Wu, J. A. D'Andrea, and K. Sakamoto. 1985. Very low frequency study. ASAFSAM-TR-84. Brooks Air Force Base, Texas : USAF School of Aerospace Medicine. 6. Graham, C., M. R. Cook, and H. D. Cohen. 1983. Human perception of 60-Hz electric and magnetic fields. Bioelectromagnetics Society 5th Annual Meeting (Abstract 0-11), Boulder, CO, June 12-17, 1983. 7. Kato, M., S. Ohta, K. Shimizu, Y. Tsuchida, and G. Matsumoto. 1989. Detection threshold of 50 Hz electric fields by human subjects. Bioelectromagnetics 10(3) : 319-327. 8. Konig, H. L. 1974. Behavioral changes in human subjects associated with ELF electric fields. Pp. 81-99 in ELF and VLF Electromagnetic Field Effects, M. A. Persinger, ed. New York, NY : Plenum Press. 9. Stollery, B. T. 1987. Effects of 50-Hz electric currents on vigilance and concentration . Br. J. Ind. Med. 44 : 111-118. 10. Stollery, B. T., D. E. Broadbent, W. R. Lee, J. C. Male, W. T. Norris, and J. A. Bonnell. 1989. Psychological functioning during human exposure to 50-Hz electric currents. Report to the Central Electricity Generating Board, Leatherhead, Surrey, U.K. 11. Justesen, D. R. 1988. Microwave and infrared radiations as sensory, motivational, and reinforcing stimuli. Pp. 235-264 in Electromagnetic

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ASSESSMENT OF THE POSSIBLE HEALTH EFFECTS OF GROUND WAVE EMERGENCY NETWORK Fields and Neurobehavioral Function, M. D. O'Connor and R. H. Lovely, eds. New York, NY : Alan R. Liss, Inc. 12. Carstensen, E. L., A. Buettner, W. L. Genberg, and M. W. Miller. 1985. Sensitivity of the human eye to power frequency electric fields. IEEE Transactions on Biomedical Engineering, BME 32 : 561-565. 13. Lin, J. C. 1990. Auditory perception of pulsed microwave radiation. Pp. 277-318 in Biological Effects and Medical Applications of Electromagnetic Energy , O. P. Gandhi, ed. Englewood Cliffs, N J : Prentice Hall. 14. Graham, C., M. R. Cook, and H. D. Cohen. 1990. Immunological and biochemical effects of 60 Hz electric and magnetic fields in humans. Final report prepared by Midwest Research Institute for the U.S. Department of Energy, Report No. DE90006671. Springfield, VA : National Technical Information Service. 15. Beischer, D., J. Grissett, and R. Mitchell. 1973. Exposure of man to magnetic fields alternating at extremely low frequency . Report NAMRL-1180, Naval Aerospace Medical Research Laboratory, NTIS. 16. Stollery, B. T. 1986. Effects of 50-Hz electric currents on mood and verbal reasoning. Br. J. Ind. Med. 43 : 339-349. 17. Stollery, B. T. 1987. Human exposure to 50-Hz currents. Pp. 445-454 in Interaction of Biological Systems with Static and ELF Electric and Magnetic Fields, L. E. Anderson, B. J. Kelman, and R. J. Weigel, eds. Twenty-third Hanford Life Sciences Symposium. Report No. CONF-841041 . Richland, WA : Battelle Pacific Northwest Laboratories. 18. Bassett, C. A. L., S. N. Mitchell, and S. R. Gaston. 1985. Pulsing electromagnetic field treatment in ununited fractures and failed arthrodeses. J. Am. Med. Assoc. 247(5) : 623-628. 19. Brighton, C. T., and S. R. Pollack. 1985. Treatment of recalcitrant non-union with a capacitively coupled electrical field. J. Bone and Joint Sur. 67-A(4) : 577-585. 20. Brighton, C. T., W. J. Hozack, M. D. Brager, R. E. Windsor, S. R. Pollack, E. J. Vreslovic, and J. E. Kotwick. 1985. Fracture healing in the rabbit fibula when subjected to various capacitively coupled electrical fields. J. Orthop. Res. 3 : 331-340.

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ASSESSMENT OF THE POSSIBLE HEALTH EFFECTS OF GROUND WAVE EMERGENCY NETWORK 21. Brighton, C. T., G. T. Tadduni, and S. R. Pollack. 1985. Treatment of sciatic denervation disuse osteoporosis in the rat tibia with capacitively coupled electrical stimulation. J. Bone and Joint Sur. 67-A : 1022-1028. 22. Brighton, C. T., L. Jensen, S. R. Pollack, B. S. Tolin, and C. C. Clark. 1989. Proliferative and synthetic response of bovine growth plate chondrocytes to various capacitively coupled electrical fields. J. Orthop. Res. 7 : 759-765. 23. Kuhlman, J. R., and C. T. Brighton. 1991. Stimulation of bovine growth plate chondrocytes with pulsed capacitively coupled electric fields. Pp. 153-158 in Electromagnetics in Biology and Medicine, C. T. Brighton and S. R. Pollack, eds. San Francisco, CA : San Francisco Press. 24. Swicord, M. L. 1989. Overview of the literature on electrical bone repair and growth stimulation . HHS Publ. No. (FDA) 90-8277. Washington, D.C. : U.S. Department of Health and Human Services. 25. Michaelson, S. M. 1979. Human responses to power-frequency exposures. Pp. 1-20 in Biological Effects of Extremely Low Frequency Electromagnetic Fields , R. D. Phillips, M. F. Gillis, W. T. Kaune, and D. D. Mahlum, eds. U.S. Department of Energy, NTIS CONF-781016. 26. National Council on Radiation Protection and Measurements (NCRP). 1986. Biological Effects and Exposure Criteria for Radiofrequency Electromagnetic Fields. NCRP Report No. 86. Bethesda, MD : National Council on Radiation Protection Measurements. 27. Stollery, B. T. 1992. Electrical fields. Pp. 211-236 in Handbook of Human Performance, D. Jones and A. Smith, eds. London, Academic Press. 28. Environmental Protection Agency. 1983. Biological effects of radiofrequency radiation. D. F. Cahill, and J. A. Elder, eds. EPA 600/8-83-026F, PB85 120848. NTIS PB85 120848. Springfield, VA : National Technical Information Service. 29. World Health Organization. 1987. Environmental Health Criteria 69: Magnetic Fields. Geneva, Switzerland : WHO. 30. Deno, D. W., and L. E. Zaffanella. 1982. Field effects of overhead transmission lines and stations. Chapter 8 in Transmission Line Reference Book, Publication Number EL-2500. Palo Alto, CA : Electric Power Research Institute.

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ASSESSMENT OF THE POSSIBLE HEALTH EFFECTS OF GROUND WAVE EMERGENCY NETWORK 31. Lovsund, P., P. A. Oberg, and S. E. G. Nilsson. 1979. Influence on vision of extremely low frequency electromagnetic fields , Acta Ophthalmol. 57 : 812-821. 32. Lovsund, P., P. A. Oberg, S. E. G. Nilsson, and T. Reuter. 1980. Magnetophosphenes: a quantitative analysis of thresholds. Med. Biol. Eng. Comput. 18 : 326-334. 33. Lovsund, P., P. A. Oberg, and S. E. G. Nilsson. 1980. Magneto- and electrophosphenes: a comparative study. Med. Biol. Eng. Comput. 18 : 758-764. 34. Mitchell, J. C., and W. D. Hurt. 1976. The biological significance of radiofrequency radiation emission on cardiac pacemaker performance. Technical Report 76-4, U.S. Air Force School of Aerospace Medicine. 35. Wever, R. 1973. Human circadian rhythms under the influence of weak electric fields and the different aspects of these studies. Intl. J. Biometeorology, 17 : 227-232. 36. Wever, R. 1974. ELF effects on human circadian rhythms. Pp. 101-144 in ELF and VLF Electromagnetic Field Effects, M. Persinger, ed. New York, NY : Plenum Press. 37. Wever, R. 1977. Effects of low-level, low frequency fields on human circadian rhythms . Neuroscience Research Progress Bulletin, 15(1) : 39-45. 38. Silny, J. 1986. The influence threshold of the time-varying magnetic field in the human organism. Pp. 105-112 in Biological Effects of Static and Extremely Low Frequency Magnetic Fields. Munich, Germany : MMV Medizin Verlag. 39. Sazanova, T. E. 1976. Physiological effects of work in the vicinity of 400-500 kV outdoor installations. Publication of the Institute of Labor Protection of the All-Union Central Council of Trade Unions, No. 46, 34-49, Moscow. 40. Waibil, R. 1975. Objective proof of the influence of 50 Hz electric fields on man. Third International Colloquium of ISSA for Prevention of Occupational Risks Due to Electricity, Marbella, Spain. Cited in E. L. Carstensen , Biological Effects of Transmission Line Fields. New York, NY : Elsevier.

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ASSESSMENT OF THE POSSIBLE HEALTH EFFECTS OF GROUND WAVE EMERGENCY NETWORK 41. Eisemann, U. B. 1976. Investigation on the long-term effect of small alternating current of 50 Hz on the human being. M.D. Dissertation, Albert-Ludwigs University, Germany. 42. Kalyada, T. V., T. I. Krivova, V. N. Nikitina, Y. A. Morozov, N. V. Revnova, and G. G. Shaposhnik. 1985. Biological action of a 50 Hz electric field on the human body. Pp. 317-332 in Proceedings of the U.S.-USSR Workshop in Physical Factors--Microwave and Low Frequency Fields, National Institute of Environmental Health Sciences, May 1985. 43. Hauf, R. 1974. Effect of 50 Hz alternating fields on man. Sonderdruck 26 : 318-320. 44. Gamberale, F., B. A. Olson, P. Eneroth, T. Lindh, and A. Wennberg. 1989. Acute effects of ELF electromagnetic fields: a field study of linesmen working with 400-kV power lines. Br. J. Indust. Med. 46 : 729-737. 45. Teresiak, Z., and M. Szuba. 1989. Harmful influence of electric field on human organism and methods of protection in high current engineering objects. Sixth International Symposium on High Voltage Engineering, Mississippi State University, New Orleans, LA, August 28-September 1, 1989. 46. Hauf, R. 1976. Influence of alternating electric and magnetic fields on human beings . Revue Generale de l'Electrique, Vol. 85, Special Issue on Research on the Biological Effects of Electric and Magnetic Fields. Pp. 31-49. 47. Rupilius, J. P. 1976. Research on the action of electric and magnetic 50 Hz alternating field on man. M.D. Thesis, Albert-Ludwigs University. Germany : J. Krause Publisher, Freiburg am Breisgau. 48. Sander, R., J. Brinkmann, and B. Kuhne. 1982. Laboratory studies on animals and human beings exposed to 50-Hz electric and magnetic fields. Paper 36-01, International Conference on Large High Voltage Electric Systems, 1-9 September, 1981, Paris. 49. Brighton, C. T. 1991. Advanced clinical applications of electromagnetic field effects: bone and cartilage. Pp. 293-308 in Electromagnetics in Biology and Medicine, C. T. Brighton and S. R. Pollack, eds. San Francisco, CA : San Francisco Press.

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ASSESSMENT OF THE POSSIBLE HEALTH EFFECTS OF GROUND WAVE EMERGENCY NETWORK 50. Pollack, S. R. 1991. Dosimetry in electromagnetic field stimulation. Report prepared for the National Institutes of Health. Department of Bioengineering: University of Pennsylvania.