Electric and Magnetic Fields
Electric and Magnetic Fields
Referred to as EMF, the fields of energy surrounding electric power wires and other current-carrying devices.
Electric power lines, household wiring, and appliances all carry electric current. Since the late 1970s, concerns have been raised about the link between electric and magnetic fields, the invisible lines of force that surround all electrical devices, and cancer. Alternating current (AC), the form of electric power used in the United States, produces fields that induce weak electric currents in objects that conduct electricity, including humans. Direct current, the form of current produced by batteries, is unlikely to induce electric current in humans. The currents induced by AC fields have been the focus of most research on how EMFs may affect human health.
Some studies in epidemiology (studies with humans to understand the cause and progression of disease) have suggested a possible link may exist between exposure to power-frequency electric and magnetic fields (EMFs) and certain types of cancer, primarily leukemia and brain cancer.
From 1979 to 1993, 14 studies analyzed the possible association between proximity to power lines and types of childhood cancer. Of these, eight have reported correlation between proximity to power lines and some form of cancer. Four of the 14 studies showed a statistically significant association with leukemia.
As of 1995, there is no scientific consensus about EMF and its relation to cancer. However, in 1992, the Energy Policy Act in the United States provided $65 million to fund the five-year program of EMF Research and Public Information Dissemination Program (EMF RAPID). The EMF RAPID program reported its findings to the U.S. Congress in 1997.
For the typical homeowner, identifying and measuring sources of EMF exposure is complex: EMF fields change constantly, depending on the power usage in the person's environment, and his or her proximity to the power source. People living close to large power lines tend to have higher overall exposures to electric fields, since fields close to transmission lines are much stronger that those surrounding household appliances. Magnetic fields, on the other hand, are stronger in close proximity to household appliances than directly beneath power lines. These magnetic fields decrease in strength with distance from the source more quickly than do electric fields.
To find out about EMFs from a particular power line, homeowners may contact the utility that operates the power line. Most utilities will conduct EMF measurements for customers at no charge. Other options are to hire an independent technician (often listed in the yellow pages of the telephone directory under "Engineers, environmental"), or to purchase a gaussmeter for self-monitoring of EMF levels.
Strategies for minimizing exposure to EMF are: increase the distance between yourself and the EMF source (keep appliances and electronics at arm's length); avoid unnecessary proximity to high EMF sources (don't play under power lines or on top of power transformers for underground lines); and reduce the time appliances operate (for example, turn computer monitor off when not in use).
EMF in Your Environment: Magnetic Field Measurements of Everyday Electrical Devices. Washington, DC: U.S. Environmental Protection Agency (EPA), 1992.
National Institute of Environmental Health Sciences and U.S. Department of Energy. Questions and Answers about EMF: Electric and Magnetic Fields Associated with the Use of Electric Power. Washington, DC: U.S. Government Printing Office, 1995.
Possible Health Effects of Exposure to Residential Electric and Magnetic Fields. Washington, DC: National Academy Press, 1997.
"Electromagnetic Fields: No Evidence of Threat." Consumers' Research Magazine 79, December 1996, pp. 23+.
Schneider, David. "High Tension: Researchers Debate EMF Experiments on Cells." Scientific American 273, no. 4, October 1995, p. 26(3).
Wartenberg, Daniel. "EMFs: Cutting Through the Controversy." Public Health Reports 111, May-June 1996, pp. 204+.
U.S. Department of Energy
Electric and Magnetic Fields (EMF) Research and Public Information Dissemination (RAPID) Program
(Information on the five-year national research and risk assessment program on EMF.)
U.S. EPA Public Information Center
Address: 401 M St., SW
Washington, DC 20460
Telephone: toll-free EMF Infoline (800) 363-2383