INTRODUCTION

The use of electricity in residential and occupational settings benefits society. The ever-expanding use of electricity has not, however, come without some risks, most notably the potential for shocks and bums from contact with energized electrical conductors. Vital Statistics of the U.S. (DHHS 1992) reported that 525 deaths in the United States in 1992 were caused by accidental electrocution; that amounts to an annual risk of two fatalities per 1,000,000 population per year.

Public concern has grown in recent years over the possibility that more subtle or delayed adverse health effects might result from exposure to power-frequency magnetic fields surrounding transmission and distribution lines and the electrical devices that have become common in residences and workplaces. Concern over the possible health effects of exposure to low-intensity, 60-hertz (60-Hz) power-frequency magnetic fields was a driving force in setting research agendas for government and private organizations and led to a series of workshops held in 1990–1992 with participation by representatives of the Department of Energy (DOE), the National Institute for Occupational Safety and Health, the Environmental Protection Agency, the Electric Power Research Institute, public utilities, state governments, and the scientific community. The workshops were designed to elicit strategies for research in the biologic effects of magnetic field (MF) exposure, and various methods of disseminating research findings to the public were considered. The workshops provided the basic framework for establishment of a national program in electric and magnetic field research that was ultimately authorized by Congress in the Energy Policy Act of 1992 (Public Law 102–486). This program is commonly called EMF-RAPID.

Congressional hearings

Two congressional hearings also were instrumental in developing the Energy Policy Act of 1992 and in implementing the research program established under the act. The first was held before the Subcommittee on Natural Resources, Agriculture Research, and Environment of the House Committee on Science, Space, and Technology. The hearing, held on July 25, 1990, was chaired by Rep. James H. Scheuer (New York). Testimony was presented by members of Congress and federal agencies, academic scientists, and representatives of electric power companies and commercial businesses with a strong interest in the outcome of research on the human health effects on MFs. The testimony presented at the heating was important in developing the goals and implementation strategy of the Energy Policy Act.

After passage of the Energy Policy Act, a second hearing was held before the Subcommittee on Energy and Power of the House Committee on Energy and Commerce. The hearing, held on April 1, 1993, was chaired by Rep. Phillip R. Sharp (Indiana). It involved testimony by officials of DOE and the National Institute of Environmental Health Sciences (NIEHS) and three scientists with expertise in epidemiology, risk analysis, and basic science related to MF effects on human health. The primary objective of this heating was to impress on DOE and NIEHS that members of Congress had a strong interest in the outcome of research funded through the Energy Policy Act.



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Research on Power-Frequency Fields: Completed Under the Energy Policy Act of 1992 INTRODUCTION The use of electricity in residential and occupational settings benefits society. The ever-expanding use of electricity has not, however, come without some risks, most notably the potential for shocks and bums from contact with energized electrical conductors. Vital Statistics of the U.S. (DHHS 1992) reported that 525 deaths in the United States in 1992 were caused by accidental electrocution; that amounts to an annual risk of two fatalities per 1,000,000 population per year. Public concern has grown in recent years over the possibility that more subtle or delayed adverse health effects might result from exposure to power-frequency magnetic fields surrounding transmission and distribution lines and the electrical devices that have become common in residences and workplaces. Concern over the possible health effects of exposure to low-intensity, 60-hertz (60-Hz) power-frequency magnetic fields was a driving force in setting research agendas for government and private organizations and led to a series of workshops held in 1990–1992 with participation by representatives of the Department of Energy (DOE), the National Institute for Occupational Safety and Health, the Environmental Protection Agency, the Electric Power Research Institute, public utilities, state governments, and the scientific community. The workshops were designed to elicit strategies for research in the biologic effects of magnetic field (MF) exposure, and various methods of disseminating research findings to the public were considered. The workshops provided the basic framework for establishment of a national program in electric and magnetic field research that was ultimately authorized by Congress in the Energy Policy Act of 1992 (Public Law 102–486). This program is commonly called EMF-RAPID. Congressional hearings Two congressional hearings also were instrumental in developing the Energy Policy Act of 1992 and in implementing the research program established under the act. The first was held before the Subcommittee on Natural Resources, Agriculture Research, and Environment of the House Committee on Science, Space, and Technology. The hearing, held on July 25, 1990, was chaired by Rep. James H. Scheuer (New York). Testimony was presented by members of Congress and federal agencies, academic scientists, and representatives of electric power companies and commercial businesses with a strong interest in the outcome of research on the human health effects on MFs. The testimony presented at the heating was important in developing the goals and implementation strategy of the Energy Policy Act. After passage of the Energy Policy Act, a second hearing was held before the Subcommittee on Energy and Power of the House Committee on Energy and Commerce. The hearing, held on April 1, 1993, was chaired by Rep. Phillip R. Sharp (Indiana). It involved testimony by officials of DOE and the National Institute of Environmental Health Sciences (NIEHS) and three scientists with expertise in epidemiology, risk analysis, and basic science related to MF effects on human health. The primary objective of this heating was to impress on DOE and NIEHS that members of Congress had a strong interest in the outcome of research funded through the Energy Policy Act.

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Research on Power-Frequency Fields: Completed Under the Energy Policy Act of 1992 The Energy Policy Act of 1992 In item 303, section 2118, the act outlined a national program—the Electric and Magnetic Fields Research and Public Information Dissemination (EMF-RAPID) program—intended to be a partnership between government and industry. Three main directives were given: to determine whether exposure to 60-Hz MFs produced by the generation, transmission, and use of electric energy affects human health; to carry out research in and development and demonstration of technologies that could mitigate any adverse human health effects; and to provide for dissemination of information related to possible human health effects of MF exposure. The legislation also called for establishment of a National EMF Interagency Committee (IAC) and a National EMF Advisory Committee (NEMFAC) to guide these efforts. The legislation directed the secretary of energy to enter into an agreement with the National Academy of Sciences (NAS) whereby NAS would evaluate the research activities completed under the program and report its findings to DOE, IAC, and NEMFAC. Electric and Magnetic Fields Research and Public Information Dissemination Program The Electric and Magnetic Fields Research and Public Information Dissemination program, in its relatively brief existence, has achieved a number of important objectives. There has been an increase in the research activity devoted to possible adverse effects of exposure to MFs on human health. An effort was made to ensure that this research activity was coordinated and targeted to produce answers to a number of important questions raised in the Energy Policy Act of 1992 (Public Law 102–486): Determine whether or not exposures to electric and magnetic fields produced by the generation, transmission, and use of electrical energy affect human health; carry out research, development, and demonstration with respect to technologies to mitigate any adverse human health effects; and provide for dissemination of information . . . to the public". The act further specifies that the program shall provide for: the collection, compilation, and dissemination of scientifically valid information on possible human health effects of electric and magnetic fields; the types and extent of human exposure to electric and magnetic fields in various occupational and residential settings; technologies to measure and characterize electric and magnetic fields; and methods to assess and manage exposure to electric and magnetic fields. research on mechanisms by which electric and magnetic fields interact with biological systems; and epidemiologic research on the possible human health effects of electric and magnetic fields; and

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Research on Power-Frequency Fields: Completed Under the Energy Policy Act of 1992 research, development, and demonstration with respect to technologies to improve the measurement and characterization of electric and magnetic fields; and techniques to assess and manage exposure to electric and magnetic fields". The act directs that the Secretary of Energy "shall enter into appropriate arrangements with the National Academy of Sciences under which the Academy shall periodically submit to the Interagency Committee and the Advisory Committee reports that evaluate the research activities under the program. The report shall include recommendations to promote the effective transfer of information derived from such research projects, including the transfer of information to representatives of State regulatory agencies, State health agencies, electric utilities, electrical equipment manufacturers, labor unions, and the public. The Secretary shall be responsible for expenses incurred by the NAS in connection with the preparation of such reports". According to the act, the Director of the National Institute of Environmental Health Sciences (NIEHS) shall report to the National EMF Interagency Committee (IAC) and National EMF Advisory Committee (NEMFAC). The IAC, in consultation with NEMFAC, shall report to the Secretary of Energy and Congress in a final report "stating the IAC's findings and conclusions on the effects, if any, of electric and magnetic fields on human health and remedial actions, if any, that may be needed to minimize any such health effects". Background Humans evolved in an environment including natural electric and magnetic fields of several types. The natural electromagnetic spectrum common to our environment covers a broad range of frequencies and wavelengths. These vary from the quasi-static geomagnetic field to low-frequency emissions of a few hertz (Hz) to a few thousand hertz associated with lightning storms. However, in the last 100 yrs, a number of human-made electromagnetic frequencies have been added to the environment. Radio transmitters and microwave ovens contribute high-frequency components to our electromagnetic environment. The transmission, distribution, and use of electric power contributes at the extremely-low-frequency (ELF) end of the frequency spectrum (the term extremely low frequency is commonly used to refer to frequencies of under 300 Hz). Power frequencies are 60 Hz in the United States and 50 Hz in Europe. The biological effects of electric and magnetic fields vary greatly depending on their frequency and field strength. The EMF-RAPID program has been concerned almost entirely with magnetic fields. It is in this context that considerable controversy was created within the scientific community when it was asserted that exposure to powerline fields was associated with increased incidence of disease. Wertheimer and Leeper (1979) reported that an increase by a factor of 2–3 in the incidence of childhood cancer was associated with residence in houses that had electrical wiring configurations that were thought to be associated with higher currents and thus higher than usual MFs. Their findings were unexpected and could not be explained by known interactions of power-frequency magnetic fields with biologic systems.

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Research on Power-Frequency Fields: Completed Under the Energy Policy Act of 1992 Many epidemiologic studies have since evaluated associations of a number of cancers, particularly leukemias and brain tumors, with estimated or measured exposures to electric fields (EFs) and MFs. Studies of cancer in children have focused on residential power-frequency magnetic field exposure; both residential and occupational exposures of adults have been examined. The reported associations are inconsistent from study to study, and effects range from none to weak. With the passage of time, such studies have generally improved in quality with respect to exposure assessment, population size, and outcome assessment, but this has not resulted in greater consistency of results, stronger associations, greater acceptance, or greater consensus about interpretation. Epidemiology can be a powerful tool for identifying potential risk factors when there is a strong correlation between increased risk of disease and specific environmental conditions. Epidemiologic studies also have been effective in identifying relatively weak associations between putative risk factors and some cancers. Epidemiology is most successful in cases where there are large differences in exposure, where the adverse effects are not rare, and when large samples can be studied prospectively. However, when association is weak, interpretations are more difficult, and conclusions concerning risk less convincing. Epidemiologic studies are at a serious disadvantage if they are used in an effort to prove that weak associations exist or do not exist. Recent epidemiologic studies of power-frequency MFs and cancer have been conducted in larger populations and with more rigorous methods, but they have not produced evidence that argues persuasively for a quantitative relationship between increased exposure to power-frequency MFs and increased risk of any particular form of human cancer (NRC 1997). The results of epidemiologic studies of the association between ELF-MF exposures and cancer are difficult to interpret for a number of reasons: There is considerable uncertainty in exposure assessment. Measurements are usually made after the time period of interest, and the relevant exposure metric is not known. Little is known about the risk factors for different leukemias and central nervous system cancers; therefore, possible confounders cannot be identified, measured. There is no accepted mechanism that can plausibly account for the causality of any association. The cancer outcomes identified are rare, as is high-MF exposure in a population; detection of a causal relationship between exposure and health effects at a level of high statistical significance therefore is difficult to achieve. For all the above reasons, quantitative estimates of the relationship between exposure level and excess cancer risk are not persuasive. People evaluating epidemiologic findings in this field can arrive at different conclusions, depending on their starting viewpoints. Those concerned about protecting public health might lean toward acceptance of a possible association between MFs and cancer risk, whereas others might reject such an association based on the lack of a plausible mechanism and the inability to identify possible confounders. All will agree that the evidence supporting an association is limited.