Possible Health Effects of Exposure to Residential Electric and Magnetic Fields (1997) / Chapter Skim
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1 Introduction
1 Introduction
Pages 9-20
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To help determine whether a potential health risk from exposure to low-strength, low-frequency electric and magnetic fields might exist, the U.S. Department of Energy (DOE)
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AREAS OF CONCERN Concern about the possible health effects of exposure to electromagnetic fields first arose when military personnel were exposed to fields of relatively high strength from high-frequency radar systems and video screens during World War II. Since then, claims have risen of adverse health effects purportedly associated with high-frequency sources, such as radar units used by police, antenna systems used by the military, cellular phones used for communication, and microwave ovens and other appliances used in homes.
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The electric and magnetic components of the fields generated by moving charged particles are formally linked and mathematically described by a set of coupled differential equations called Maxwell's equations. Electromagnetic fields are characterized by their wavelength, A (expressed in meters)
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, which produce the electricity; high-voltage transmissions lines, which carry the electricity to major population centers; substations and their transformers, which reduce the voltage to levels suitable for distribution within a population center; distribution lines (distribution primaries) , which commonly carry power along residential streets; distribution transformers, which reduce the voltage to amounts suitable for use in homes; and distribution secondaries (service drops)
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On the other hand, magnetic fields pass through the body and can induce electric currents throughout the body. Magnetic fields can pass through most common building materials, including thin sheets of metal.
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These are cancer, primarily childhood leukemia; reproductive and developmental effects, primarily abnormalities and premature pregnancy termination; and neurobiologic effects, primarily learning disabilities and behavioral modifications. Each of those effects has been reported in epidemiologic studies to be associated with exposure to some indirect estimates of the strength of power-frequency electric and magnetic fields.
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One recent publication developed for the lay reader by Morgan (1995) describes quantitative assessments that place an upper limit on the lifetime risk of cancer due to exposure to electric and magnetic fields and compares that risk with other common risks.
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Electric substations are installations where the voltages used with transmission lines are stepped down to lower voltages used with distribution lines. Electric and magnetic fields produced by substation equipment are generally not appreciable beyond the substation boundaries, but the fields can be somewhat stronger near them than in other parts of the neighborhood, because the power lines converge at the substation and might be closer to the ground as they go in and out of the substation.
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It is also apparent that the potential health effects are only one part of the concern. If extreme steps are taken to reduce exposure to power-frequency electric and magnetic fields, large sums of money will need to be expended (e.g., to bury transmission and distribution lines, to redesign residential wiring and electric appliances, or to retrofit existing ones)
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The ORAU report concluded that there was "no convincing evidence in the published literature to support the contention that exposures to extremely-low-frequency electric and magnetic fields (ELF-EMF) generated by sources such as household appliances, video display terminals, and local power lines are demonstrable health hazards." They noted that the results of their review did not justify an expansion of the national research effort to investigate the health effects of exposure to electric and magnetic fields and that "in the broad scope of research needs in basic science and health research, any health concerns over exposures to ELF-EMF should not receive a high priority." In 1989, the Office of Technology Assessment published a 103-page background paper prepared for them by Carnegie Mellon University's Department of Engineering and Public Policy and entitled "Biological Effects of Power Frequency Electric and Magnetic Fields" (Nair et al.
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This chapter also describes the way ELF magnetic fields interact with biologic systems. In Chapter 3, the committee summarizes what has been learned about the biologic effects of exposure to power-frequency electric and magnetic fields from cellular and molecular studies in the laboratory.
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20 HEALTH EFFECTS OF RESIDENTIAL ELECTRIC AND MAGNETIC FIELDS lion, committee members individually and collectively ascribed different weights to the importance of the papers evaluated and the quality of the research therein. The committee members often had specialized criteria based on their individual disciplines for evaluating the literature; the criteria are described in the report.
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