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What are EMFs?
Are EMFs dangerous?
What have the studies of cancer in people living near power lines found?
Do electrical workers have higher risks of cancer?
If EMFs really do cause or promote cancer, shouldn't cancer rates have increased along with the increased use of electricity?
Besides cancer, what other kinds of effects have been reported in epidemiologic studies citing EMFs?
What effects of EMFs have been reported in laboratory studies?
What about effects of EMFs on the hormone Melatonin?
What have governmental reviews concluded about EMFs and cancer?
How can I find out how strong the EMFs are where I live or work?
What can be done to limit EMF exposures?
There are many Federal Government Publications available.
And public information from nonfederal sources.
1. What are EMFs?
Although we cannot see, hear or feel them, electromagnetic fields (EMFs) are found throughout nature and all living things. EMFs are also present wherever electricity is generated from 50/60 Hertz AC power sources. Power lines, electrical wiring, and appliances all produce electric and magnetic fields. EMFs are invisible lines of force that surround any electrical device. Electric and magnetic fields have different properties and possibly different ways of causing biological effects. Note that while electric fields are easily shielded or weakened by conducting objects (e.g., trees, buildings, and human skin), magnetic fields are not. However, both electric and magnetic fields weaken with increasing distance from the source. Even though electric and magnetic fields are present around appliances and power lines, more recent interest and research have focused on potential health effects of magnetic fields. This is because epidemiological studies have found associations between increased cancer risk and power-line configurations, which are thought to be surrogates for magnetic fields.
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2. Are EMFs dangerous?
Laboratory studies have shown that EMFs can affect living cells but it is unclear whether these effects are harmful. Some epidemiological studies have reported a possible link between EMF exposure and cancer. Other studies indicate that continuous exposure to levels as low as 2 milliGauss (mG) may be harmful. Current research is expected to provide more answers about potential health effects within the next few years. Until then, it's best to play it safe and know the level of EMFs in your home and work environment.
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3. What have the studies of cancer in people living near power lines found?
To date, 14 studies have analyzed a possible association between proximity to power lines and various types of childhood cancer. Of these, eight have reported positive associations between proximity to power lines and some form(s) of cancer. Four of the 14 studies showed a statistically significant association with leukemia.
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4. Do electrical workers have higher risks of cancer?
Several studies have reported increased cancer risks for jobs involving work around electrical equipment. To date, it is not clear whether these risks are caused by EMFs or by other factors. A report published in 1982 by Dr. Samuel Milham was one of the first to suggest that electrical workers have a higher risk of leukemia than do workers in other occupations. The Milham study was based on death certificates from Washington state and included workers in 10 occupations assumed to have elevated exposure to EMFs. A subsequent study by Milham, published in 1990, reported elevated levels of leukemia and lymphoma among workers in aluminum smelters, which use very large amounts of electrical power. Dr. Joseph Bowman published a report in 1992 which provided some information about actual EMF exposures of various electrical workers. For this study, the category "electrical workers" included electrical engineering technicians, electrical engineers, electricians, power line and cable workers, power station operators, telephone line workers, TV and radio repairmen, and welders and flame cutters. Electrical workers in Los Angeles and Seattle did have higher EMF exposures than nonelectrical workers.
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5. If EMFs really do cause or promote cancer, shouldn't cancer rates have increased along with the increased use of electricity?
Not necessarily. Although use of electricity has increased greatly over the years, EMF exposures have probably not increased in the same way. Changes in the way that buildings are wired and in the way electrical appliances are made have in some cases resulted in lower magnetic field levels. Rates for various types of cancer have shown both increases and decreases through the years. For example, mortality rates (deaths) for the two most common cancers in children have decreased because of better treatment. Incidence rates (numbers of new cases) have increased for unknown reasons. Incidence rates can reflect changes in exposures to various environmental agents, and they are also affected by changes in how cancers are diagnosed and reported.
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6. Besides cancer, what other kinds of effects have been reported in epidemiologic studies citing EMFs?
Several epidemiological studies have looked for EMF effects on pregnancy outcomes and general health. Various EMF sources have been studied for possible association with miscarriage risk: power lines and substations, electric blankets and heated water beds, electric cable ceiling heat, and computer monitors or video display terminals (VDTs). Some studies have correlated EMF exposure with higher than expected miscarriage rates; others have found no such correlation. Epidemiological studies have revealed no evidence of an association between EMF exposure and birth defects in humans. One preliminary report released in 1994 has suggested a possible link between occupational EMF exposure and increased incidence of Alzheimer's disease. This study also found a higher incidence of Alzheimer's disease among tailors and dressmakers.
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7. What effects of EMFs have been reported in laboratory studios?
Several kinds of biological effects have been reported in studies of electric and/or magnetic fields. A biological effect is a measurable change in some biological factor. It may or may not have any bearing on health. Some effects of 60-Hz EMFs reported in laboratory studies include: changes in functions of cells and tissues, decrease in the hormone melatonin, alterations of immune system, accelerated tumor growth, changes in biorhythms, and changes in human brain activity and heart rate.
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8. What about effects of EMFs on the hormone Melatonin?
Melatonin is a hormone produced mainly at night by the pineal, a small gland in the brain. One reason scientists are interested in melatonin is that it could help explain results of some EMF epidemiological studies. Melatonin has been reported to slow the growth of some cancer cells, including breast cancer cells, in laboratory experiments. If power-frequency EMF can affect melatonin in humans, this could be a mechanism to explain results of some EMF studies of breast cancer.
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9. What have governmental reviews concluded about EMFs and cancer?
Most recent reviews have concluded that the existing evidence, although suggestive, does not show that EMFs cause cancer. These include national reviews by the U.S. Environmental Protection Agency, the Committee on Interagency Radiation Research and Policy Coordination, the Australian Minister of Health, the National Radiological Protection Board of the United Kingdom, the Danish Ministry of Health, the French National Institute of Health and Medical Research, and reviews sponsored by the states of California, Texas, Connecticut, Illinois, Maryland, and Colorado. The Swedish government issued a public information document in May 1994 that states, "We suspect that magnetic fields may pose certain risks to health, but we cannot be certain. While research is under way to pin this down, the report continues, "there is a good reason to exercise a certain amount of caution." The Swedish government recommends against locating new homes and schools near existing electricity generating plants and proposes that high magnetic fields in homes, schools, and workplaces be limited.
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10. How can I find out how strong the EMFs are where I live or work?
For specific information about EMFs from a particular power line, contact the utility that operates the line. Most utilities will conduct EMF measurements for customers, often at no charge. You can make your own field measurements if you have a gaussmeter, such as the ElectroSensor from Sonic Technology Products. Independent measurement technicians will conduct EMF measurements for a fee.
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11. What can be done to limit EMF exposures?
There are many ways to reduce exposures to EMFs. Some are as easy as standing back from an appliance when it is in use. Electromagnetic fields from appliances drop off dramatically in strength with increased distance from the source.
Other EMF reduction steps, such as correcting a household wiring problem, are worth doing anyway for safety reasons. But what about more costly actions, such as burying power lines or moving out of a home? Because scientists are still debating whether EMFs are a hazard to health, it is not clear how much should be done at this time to reduce exposures. However, prudent avoidance dictates that it is better to err on the overly cautious side until we know for sure what EMF levels are considered "safe" or "hazardous". Some authorities recommend taking simple precautionary steps, such as:
Increase the distance between yourself and the EMF source. Sit at arm's length from your computer terminal, make sure your clock radio is as far away from you as possible while you sleep.
Avoid unnecessary proximity to high EMF sources. Don't let children play directly under power lines or on top of power transformers for underground lines.
Reduce time spent in the field. Turn off your computer monitor and other electrical appliances when you aren't using them.
Still have more questions? Call the EMF Infoline (managed by the U.S. Environmental Protection Agency) at 1-800-363-2383, or National Institute for Occupational Safety and Health (NIOSH) at 1-800-356-4674.
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12. There are many Federal Government Publications available:
EMF in Your Environment: Magnetic Field Measurements of Everyday Electrical Devices, U.S. Environmental Protection Agency (EPA), 1992. 32 pp. Available free from the U.S. EPA Public Information Center, 401 M Street, SW; Washington, DC 20460. Designed for the general public, this booklet focuses on appliances as EMF sources. Includes tables showing magnetic field strengths at varying distances from 38 common electric appliances. Power lines and transportation sources are also discussed.
Questions and Answers About Electric and Magnetic Fields Associated with the Use of Electric Power, National Institute of Environmental Health Sciences and U.S. Department of Energy, 1995. 66 pp. This booklet can be purchased from the Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402. Phone 202-512-1800. Also available in Spanish.
Electric and Magnetic Fields and the Potential Hazard to Human Health, National Institute of Environmental Health Sciences (NIEHS), 1994. 6 pp. Available free: call 919-541-5085. Fact sheet provides concise description of EMF research issues, highlighting work at NIEHS since 1988 and new interagency research effort.
Electric and Magnetic Fields (EMF) Research and Public Information Dissemination (RAPID) Program: Research Agenda and Communication Plan, EMF RAPID Program Interagency Committee, 1994. 10 pp. Available from the U.S. Department of Energy: call 202-586-5575 (request publication no. DOE/EE-0021). Also available from the National Institute of Environmental Health Sciences: call 919-541-5085. Describes agenda for 5-year national research and risk assessment program on EMF.
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13. Public Information from Nonfederal Sources
Answers to Frequently Asked Questions about Electric and Magnetic Fields (EMFs) Produced by 60-Hertz (Hz) Electric Power, Massachusetts Department of Public Health, 1993. Available free: call 617-727-7170. Public information fact sheet gives basic, consumer-oriented information on EMF health effects issue.
Electric and Magnetic Field Fundamentals: An EMF Health Effects Research Paper, Electric Power Research Institute (EPRI), March 1994. Available from EPRI. Call 510-934-4212; request publication no. BR-103745.
EPRI Resource Papers on EMF, EPRI. Single free copies available to nonprofit, government, and education organizations: call 510-934-4212. Series of resource papers, geared to a technical audience, covering exposure assessment, epidemiology, and basic EMF fundamentals.
Your Guide to Understanding EMF, 1993. 15 pp. Colorful brochures give simple presentation of basic EMF issues. Spanish versions are available. Can be purchased from the Culver Company: call 800-428-5837.
Dr. Granger Morgan and colleagues at Carnegie Mellon University produced the three booklets below on EMF to present technical information for a non-technical audience. Available from Carnegie Mellon for $5.50 each.
Electric and Magnetic Fields from 60 Hertz Electric Power: What Do We Know About Possible Health Risks? 1989. 45 pp., Measuring Power Frequency Fields, 1992. 25 pp., What Can We Conclude from Measurements of Power Frequency Fields?
1993. 45 pp