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Questions and Answers - EMF in the Workplace SEPTEMBER 1996
Electric and Megnetic Fields Associated with the Use of Electric Power
NATIONAL INSTITUTE FOR OCCUPATIONAL SAFETY AND HEALTH
NATIONAL INSTITUTE OF ENVIRONMENTAL HEALTH SCIENCES U.S. DEPARTMENT OF ENERGY
Funding for this booklet was provided by the Electric and Magnetic Fields (EMF) Research and Public Information Dissemination (RAPID) Program. EMF RAPID is a national program that combines government and private resources to study and provide answers to questions about electric and magnetic fields (EMFs).
The booklet was written by staff members of the U.S. Department of Energy (DOE), the National Institute for Occupational Safety and Health (NIOSH), the National Institute of Environmental Health Sciences (NIEHS), and Oak Ridge National Laboratory. It was reviewed by experts from federal and state agencies, academic institutions, national laboratories, citizen groups, labor organizations, and industry.
EMF In the Workplace is the second public information booklet produced by the EMF RAPID Program and focuses on occupational EMF exposure. Information about residential EMF exposure is provided in a previous booklet:
Questions and Answers About EMF.
Multiple copies of this booklet can be purchased from the Superintendent of Documents U.S. Government Printing Office Washington, D.C. 20402 (202) 512-1800
What's Inside
It is a modern fact of life that whether we are at work, at home, or at school, we are all exposed to EMFs-electric and magnetic fields produced by the generation, transmission, and use of electricity.
Some human health studies suggest that there may be a link between exposure to EMFs and certain types of cancer, primarily leukemia and brain cancer. Some scientists doubt that this apparent connection between EMF exposure and cancer is real, because it is difficult to explain biologically and because the research results are inconsistent. Most agree that more information is needed to resolve the issue about whether or not EMFs affect human health. The U.S. government has initiated a national EMF research effort and important study results are expected in the next few years.
The purpose of this booklet is to provide information about EMF exposure in the workplace. The booklet describes what researchers have learned (and have yet to learn) about EMFs and identifies some sources of EMFs in various industries.
At present, we do not have enough information to determine if EMF exposure causes adverse health effects. The information in this booklet should help workers and employers understand the scientific basis for the concerns and the uncertainties about EMF exposure.
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Contents
EMF Basics
Reviews basic terms about electric and magnetic fields.
Human Health Studies
Gives background information about epidemiology and summarizes results of major occupational EMF studies.
Biological Studies
Describes biological studies that examine EMF effects on animals and individual cells.
Summaries and Opinions
Gives a sampling of opinions from individuals and organizations that have studied the EMF issue.
Ongoing Research
Summarizes the current U.S. government EMF research effort.
Your EMF Environment
Discusses typical EMF exposures in various work environments and identifies EMF sources.
For More Information
Lists sources of additional information including toll-free telephone hotlines, an Internet listing, and publications written for a general audience.
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EMF Basics
This chapter reviews basic terms needed to understand electric and magnetic fields, compares EMF with other forms of electromagnetic energy, and briefly discusses how much such fields may affect us.
What are EMFs?
Electric and magnetic fields (EMFs) are produced by power lines, electrical wiring, and electrical equipment.
There are many other sources of EMFs. The focus of this booklet is on EMFs associated with the generation, transmission, and use of electric power. EMFs are invisible lines of force that surround any electrical device. Electric fields are produced by voltage and increase in strength as the voltage increases.
The electric field strength is measured in units of volts per meter (V/m). Magnetic fields result from the flow of current through wires or electrical devices and increase in strength as the current increases. Magnetic fields are measured in units of gauss (G) or tesla (T). Most electrical equipment has to be turned on, i.e., current must be flowing, for a magnetic field to be produced. Electric fields, on the other hand, are present even when the equipment is switched off, as long as it remains connected to the source of electric power (see the following page).
Electric fields are shielded or weakened by materials that conduct electricity (including trees, buildings, and human skin). Magnetic fields, on the other hand, pass through most materials and are therefore more difficult to shield. Both electric and magnetic fields decrease as the distance from the source increases.
Even though both electric and magnetic fields are present around electrical equipment and power lines, most recent research has focused on potential health effects of magnetic fields. This is because some epidemiologic studies have reported an increased cancer risk associated with estimates of magnetic field exposure. (See the Human Health Studies chapter for a summary of these studies.) No similar associations have been reported for electric fields.
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Current flowing through a conductor creates magnetic fields, which form continuous loops around the current.
Everything that carries electric power produces electric and magnetic fields. This includes power lines, wiring, and electrical equipment.
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