The ELF in Your Electric Blanket
Magazine article by Dixie Farley; FDA Consumer, Vol. 26, December 1992
Magazine Article Excerpt
The ELF in Your Electric Blanket (and Other Appliances) (Extremely Low Frequency Electric and Magnetic Fields) (Cover Story) by Dixie Farley Scientists at many institutions, including the Food and Drug Administration, are studying the extremely low frequency electric and magnetic fields emanating from electrical devices, because of claims about possible effects on the body. To date, worldwide research on ELF fields provides no firm evidence of harm, but certain experiments are causing some scientists to be concerned about the possibility, stimulating still more research. Some products, such as video display terminals and electric blankets, have received special attention. All electrical devices produce some type of electric, magnetic or electromagnetic fields, but not all at the same frequency--a measure of how rapidly fields change with time. Mays Swicord, Ph.D., chief of FDA's radiation biology branch, stresses that each frequency may be distinct in terms of potential effect: "A particular biological response or effect may result from exposures to one frequency, but not others. Or a response may result from exposure to several frequencies but be due to entirely different mechanisms. In other words, one shouldn't assume that an effect or problem seen on one region of the electromagnetic spectrum will occur in some other region." It's well-known that overexposure to x-rays and ultraviolet radiation, both very high in the spectrum, pose health risks by breaking chemical bonds in cellular molecules. ELF fields are unable to break such bonds, but they may act through some more subtle mechanisms. Studies most often name magnetic field strength as the property that is perhaps capable of producing effects. The Federal Food, Drug, and Cosmetic Act requires that FDA, through its Center for Devices and Radiological Health (CDRH), evaluate electromagnetic emissions to eliminate unnecessary exposure. CDRH research on lower frequencies centered first on microwave radiation. It shifted to ELF in 1987 after epidemiological data increasingly indicated a small, but statistically significant, association with cancer. CDRH now has one of largest federal in-house ELF research programs. On Nov. 26, 1991, U.S. Representatives George Brown, D-Calif., and James Scheuer, D-N.Y., introduced the National Electromagnetic Fields Research and Public Information Dissemination Act. Incorporated into the Comprehensive National Energy Policy Act earlier this year, its provisions call for an interagency advisory committee to coordinate ELF research and public information activities. The Energy Act became law Oct. 24. Problems with Looking for Problems ELF research is especially difficult, says Larry Cress, M.D., a CDRH radiation biology branch scientist conducting ELF research at the cellular level. "For one thing," he says, "we're probably looking for very small changes. In fact, according to some physicists, the energy in 60-hertz fields [U.S. electric power] is too low to have any effect on biological systems. But this doesn't take into account that energetic molecules in the cell membrane may act as amplifiers to increase the effect of an external signal." Another problem with ELF research is that results are hard to repeat. "Many researchers have been able to reproduce their effects most, but not all, of the time," Cress says. "And we don't see a dose response, as with some radiation, such as x-ray. Or, one laboratory may see an increase in something in a cell when the field is turned on, while another laboratory sees a corresponding decrease when the field is turned on. The reason probably is that unexplained factors are affecting the ELF fields' interaction with cells. One theory is that the Earth's magnetic field interacts with power-line fields. The Earth's magnetic field tends to vary geographically. It varies quite a bit from room to room in our own lab." There are certain frequency bands, socalled windows, at which some people see effects, Cress says. "If you're not tuned to one of those windows, you can spend your life looking, and you'll never see anything. So we need to find the windows. And the windows may not be the same for all effects." The basic problem, he says, is what to measure. If there is a harmful effect, is it from the electric or the magnetic field? Or is it from changes in fields? "For example," he says, "in some electric blanket designs, the power is switched on and off at intervals to control the temperature. The changing magnetic field when the current drops and rises might be the important factor for biological effects." ELF fields are beneficial to health in at least one way.Cress explains: "Sometimes, after months and months of being pinned, casted and dressed, a bone fracture just ... |
End of free preview...
To continue reading this publication, you must have a Questia Subscription.
Try Us Today! Click Here
Questia provides the world's largest online library of scholarly books and journal articles, with integrated footnote and bibliography tools, highlighting, note taking and book marking. With a Questia subscription, you'll have access to the full text of more than 67,000 books and 1.5 million articles.
Already a subscriber? Login:
Sponsored Links
Free Newsletter
Get helpful how-to's, writing tips, search strategies, quizzes & more!
Search the Library
