EMF Health Effects

Health Research Supporting the Creation
of Low EMF Environments



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Health effects studies over the past several years have shown a consistent correlation between exposure to elevated EMF levels (power frequency magnetic fields) and the development of adverse health effects. The source of these fields may be a power line, electrical equipment, or mis-wired electrical circuits within a building, but the fields are the same regardless of their source. Unfortunately, there are no national standards to prevent the introduction of such problems into new construction. Most of the effort in creating a low EMF environment involves the elimination of magnetic and electric fields from the wiring system, although in some cases radio frequency (RF) fields may be an issue as well. In light of the research summarized below, many people today are choosing to take a cautious and pro-active approach in regard to electromagnetic fields, and to limit their exposure where possible. This action often begins at home, in the creation of a low-EMF environment.

1979   Wertheimer and Leeper

The first scientific study to attract serious interest in the issue came in 1979. Epidemiologist Nancy Wertheimer, along with physicist Ed Leeper, were looking for possible causes for a number of childhood leukemia cases in the Denver metropolitan area. Their research found that children with leukemia were more than twice as likely to have lived in homes near high current power lines, where the electromagnetic fields were stronger.1 Research on the issue has proceeded since that time, with many hundreds of studies having been completed over the past two decades, and others currently underway. These studies have often produced mixed results, but there has been a consistent pattern of elevated risk for some types of exposure, and for some conditions.

1999   National Institute of Environmental Health Sciences

The most substantial and coordinated effort to investigate the issue was the Research and Public Information Dissemination Program (RAPID). Mandated by Congress as a part of the Energy Policy Act of 1992, it was planned as a five year effort to determine if exposure to low level, low frequency electromagnetic fields is detrimental to health, and if so, to provide an assessment of risk. All prior work in the field was reviewed, and new research was funded. The final report from this research program was released in 1999 by the National Institute of Environmental Health Sciences.2 Although it states that “the probability that EMF exposure is truly a health hazard is currently small,” it also acknowledges that exposure “cannot be recognized as completely safe.” In regard to childhood leukemia, and in regard to chronic lymphocytic leukemia in occupationally exposed adults, the NIEHS acknowledged a “fairly consistent pattern of a small, increased risk with increasing exposure...” Stated in simple terms, the risk appears to be small, but there is a risk nonetheless. NIEHS Director Kenneth Olden, Ph.D., quoted in the press release, states that “efforts to encourage reductions in exposure should continue. For example, industry should continue efforts to alter large transmission lines to reduce their fields and localities should enforce electrical codes to avoid wiring errors that can produce higher fields.”

2001   International Agency for Research on Cancer (IARC)

A panel of scientists convened by the International Agency for Research on Cancer (IARC) has produced a review of health effects from static and extremely low frequency (ELF) electric and magnetic fields.3 The press release announcing the report states: "Special attention has focussed on leukaemia and on brain tumours, which early reports had suggested might be increased. IARC has now concluded that ELF magnetic fields are possibly carcinogenic to humans, based on consistent statistical associations of high level residential magnetic fields with a doubling of risk of childhood leukaemia." The report found no consistent evidence that childhood exposures were associated with brain tumors, or that adult exposures were associated with cancer of any type.

2002   California Department of Health Services

In October 2002, the California Department of Health Services released a report on the risks of EMF exposure.4 This evaluation is based upon the results of published research studies, the NIEHS Working Group Report, and studies conducted by the California EMF Program. As stated in the report's Executive Summary: “To one degree or another, all three of the DHS scientists are inclined to believe that EMFs can cause some degree of increased risk of childhood leukemia, adult brain cancer, Lou Gehrig's Disease, and miscarriage. They strongly believe that EMFs do not increase the risk of birth defects, or low birth weight. They strongly believe that EMFs are not universal carcinogens, since there are a number of cancer types that are not associated with EMF exposure.” The conclusions of the California scientists relied more upon studies of human populations and less upon animal and cell studies than most earlier evaluations. While the incidence of most of the conditions identified above is quite low, with or without EMF exposure, the incidence of miscarriage is already quite high, about 10 in 100 pregnancies. This report speculates that, based on a limited number of studies, "the theoretical added risk for an EMF-exposed pregnant woman might be an additional 10 per 100 pregnancies..."

The types of high EMF exposures implicated in the California report are produced by "... unusual configurations of wiring in walls, grounded plumbing, nearby power lines, and exposure from some jobs in electrical occupations."

Pooled Analysis of Multiple Studies (Meta-analyses)

One of the limitations of many of the epidemiologic studies conducted throughout the 1980s and 1990s was a small sample size, especially a small number of subjects who had the illnesses being investigated. Because of this, full statistical significance was not always achieved, or was achieved for only part of the data set. One approach that can be used to overcome this limitation is a technique called meta-analysis. It is sometimes possible to combine the data from multiple small studies to create a larger sample size, and thus draw statistically significant conclusions that were not possible with the individual studies alone. Two such pooled analyses that were published in 2000 found a consistent tendency toward an elevated risk for childhood leukemia, with results that were statistically significant.5,6


  1. Wertheimer, N. and Leeper, E. Electrical wiring configurations and childhood cancer. Am J Epidemiology. 1979;109(3):273-284
  2. NIEHS Report on Health Effects from Exposure to Power-Line Frequency Electric and Magnetic Fields. National Institute of Environmental Health Sciences of the U.S. National Institutes of Health. 1999. NIH Publication No. 99-4493.
  3. Static and Extremely Low Frequency (ELF) Electric and Magnetic Fields. International Agency for Research on Cancer (IARC). 2001.
  4. An Evaluation of the Possible Risks From Electric and Magnetic Fields (EMFs) From Power Lines, Internal Wiring, Electrical Occupations, and Appliances. California Department of Health Services. 2002.
  5. Greenland S, Sheppard AR, Kaune WT, Poole C, Kelsh MA. A pooled analysis of magnetic fields, wire codes, and childhood leukemia. Epidemiology 2000;ll:624-634.
  6. Ahlbohm A, Day N, Feychting M, Roman E, Skiner J, Dockerty J, Linet M, McBrice M, Michaelis J, Olsen JH, Tynes T, Verkasallo PK. A pooled analysis of magnetic fields and childhood leukemia. British J Cancer 2000; 83:692-698.

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