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
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
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
- Wertheimer, N. and Leeper, E. Electrical wiring configurations and childhood cancer. Am J Epidemiology.
- 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.
- Static and Extremely Low Frequency
(ELF) Electric and Magnetic Fields. International Agency for Research on Cancer (IARC). 2001.
- 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.
- 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.
- 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;