No Adverse Health Effects Seen From Residential Exposure to Electromagnetic Fields

WASHINGTON -- No clear, convincing evidence exists to show that residential exposures to electric and magnetic fields (EMFs) are a threat to human health, a committee of the National Research Council has concluded in a new report. After examining more than 500 studies spanning 17 years of research, the committee said there is no conclusive evidence that electromagnetic fields play a role in the development of cancer, reproductive and developmental abnormalities, or learning and behavioral problems.

"The findings to date do not support claims that electromagnetic fields are harmful to a person's health," said committee chair Charles F. Stevens, investigator, Howard Hughes Medical Institute, and professor, Salk Institute, La Jolla, Calif. "Research has not shown in any convincing way that electromagnetic fields common in homes can cause health problems, and extensive laboratory tests have not shown that EMFs can damage the cell in a way that is harmful to human health."

Concern about the health effects from EMFs arose in 1979 when researchers showed that children living close to high concentrations of certain types of electrical wires were 1.5 times more likely to develop leukemia. Because it is difficult, time-consuming, and expensive to measure electric fields in a home over a long period of time, researchers relied on a substitute to estimate the levels of electromagnetic fields to which residents may have been exposed. Using factors such as the size of wires going past the home and distance between the home and power lines, researchers estimated the fields inside.

The Research Council committee's report says that studies in the aggregate show a weak but statistically significant correlation between the incidence of childhood leukemia, which is rare, and wire configurations. It never has been demonstrated that this apparent association was caused by exposure to electromagnetic fields, however. Outside wiring correlates poorly with measurements of actual fields inside the home, in that it accounts for only a fraction of the fields inside. Scientists have tried unsuccessfully to link leukemia to EMFs by measuring fields inside of homes of children who had the disease. The results "have been inconsistent and contradictory and do not constitute reliable evidence of an association," the report says.

The weak link shown between proximity to power lines and childhood leukemia may be the result of factors other than magnetic fields that are common to houses with the types of external wiring identified with the disease. These possible factors include a home's proximity to high traffic density, local air quality, and construction features of older homes that fall into this category, the committee said.

Cells, Tissues Unaffected

To try to explain and expand on the knowledge gained from early epidemiologic studies, researchers have studied the potential effects of EMFs on individual human cells or tissues, and on animals. To date, they have found no evidence to show that EMFs can alter the functions of cells at levels of exposure common in residential settings. Only at levels between 1,000 and 100,000 times stronger than residential fields have cells shown any reaction at all to EMF exposure, and even these changes -- mainly in the chemical signals that cells send to each other -- are not a clear indication of the potential for adverse health effects. In fact, exposure may actually help the body in some subtle ways, for example by speeding up the healing process after a bone is broken.

Most important, there has been no case in which even tremendously high exposure to EMFs has been shown to affect the DNA of the cell, damage to which is believed to be essential for the initiation of cancer. Similarly, no animal experiments have shown that EMFs, even at high doses, can act as a direct carcinogen or can affect reproduction, development, or behavior in animals.

Future Research

Electromagnetic fields are generated by wires or electrically powered devices, and dissipate quickly, like light. When assessing potential impact of EMFs on health, scientists focus mainly on magnetic fields produced by power lines and electric appliances, which can pass through the body and generate small electric currents. Unlike magnetic fields, electric fields themselves lose most of their strength when they pass through metal, wood, or even skin. In fact, the strongest of either fields that the body encounters are the electric currents produced naturally when the heart beats, or as nerves and muscles unction, the report says.

The committee focused on the health studies of low-frequency electric and magnetic fields common in homes. Sources of exposure include transmission and distribution lines and electric appliances, including shavers, hair dryers, video display terminals, and electric blankets. The committee did not study in detail occupational exposures, such as those experienced by electrical workers close to higher-frequency power lines.

New research is needed to answer some of the questions that linger after nearly two decades of intensive research, the committee said. Most compelling is the need to pinpoint the unexplained factor or factors causing a small increase in childhood leukemia in houses close to power lines. The precise factors that are related to an increased number of childhood leukemia cases need to be identified.

The committee also called for more research into the relationship between high exposures to EMFs and breast cancer in animals already exposed to other carcinogens, and on reasons why electromagnetic fields seem to affect the levels of the hormone melatonin in animals, an effect not reproduced in humans.

This congressionally requested study by the National Research Council was sponsored by the U.S. Department of Energy. The National Research Council is the principal operating arm of the National Academy of Sciences and the National Academy of Engineering. It is a private, non-profit institution that provides science and technology advice under a congressional charter.

Pre-publication copies of Possible Health Effects of Exposure to Residential Electric and Magnetic Fields are available from the National Academy Press at the mailing address in the letterhead; tel. (202) 334-3313 or 1-800-624-6242. The cost of the report is $45.00 (prepaid) plus shipping charges of $4.00 for the first copy, and $.50 for each additional copy. Reporters may obtain pre-publication copies from the Office of News and Public Information at the letterhead address (contacts listed above).

NATIONAL RESEARCH COUNCIL
Commission on Life Sciences
Board on Radiation Effects Research

Committee on the Possible Effects of Electromagnetic Fields on Biologic Systems

Charles F. Stevens, M.D., Ph.D. (1) (chair)
Professor and Investigator
Howard Hughes Medical Institute
Salk Institute
La Jolla, Calif.

David A. Savitz, Ph.D. (vice chair)
Professor, Department of Epidemiology
School of Public Health
University of North Carolina
Chapel Hill

Larry E. Anderson, Ph.D.
Staff Scientist
Pacific Northwest Laboratories
Richland, Wash.

Daniel A. Driscoll, Ph.D.
Program Research Specialist
Office of Energy Efficiency and Environment
New York Department of Public Service
Albany

Fred H. Gage, Ph.D.
Professor, Laboratory of Genetics
Salk Institute
La Jolla, Calif.

Richard L. Garwin, Ph.D. (1,2,3)
IBM Fellow Emeritus, IBM Research Division
Thomas J. Watson Research Center
Yorktown Heights, N.Y.

Lynn W. Jelinski, Ph.D.
Director, Biotechnology, and Professor of Engineering
Center for Advanced Technology - Biotechnology
Cornell University
Ithaca, N.Y.

Bruce J. Kelman, Ph.D., D.A.B.T.
National Director of Health and Environmental Sciences
Golder Associates Inc.
Redmond, Wash.

Richard A. Luben, Ph.D.
Associate Professor of Biomedical Sciences and Biochemistry
Division of Biomedical Sciences
University of California
Riverside

Russel J. Reiter, Ph.D.
Professor, Department of Cellular and Structural Biology
University of Texas Health Sciences Center
San Antonio

Paul Slovic, Ph.D.
President
Decision Research
Eugene, Ore.

Jan A.J. Stolwijk, Ph.D.
Professor of Epidemiology and Acting Chair
Department of Epidemiology and Public Health
Yale University School of Medicine
New Haven, Conn.

Maria A. Stuchly, Ph.D.
Professor, and NSERC/BC Hydro/TransAlta
Industrial Research Chair
Department of Electrical and Computer Engineering
University of Victoria
British Columbia, Canada

Daniel Wartenberg, Ph.D.
Associate Professor, Department of Environmental and
Community Medicine
Robert Wood Johnson Medical School
University of Medicine and Dentistry of New Jersey
Piscataway

John S. Waugh, Ph.D. (1)
Institute Professor
Department of Chemistry
Massachusetts Institute of Technology
Cambridge

Jerry R. Williams, Sc.D.
Professor of Oncology
Johns Hopkins Oncology Center
Baltimore

RESEARCH COUNCIL STAFF

Larry H. Toburen, Ph.D.
Study Director

John D. Zimbrick, Ph.D.
Board Director

Lee R. Paulson
Senior Staff Officer

(1) Member, National Academy of Sciences
(2) Member, National Academy of Engineering
(3) Member, Institute of Medicine