Electric Power Lines, Electromagnetic Fields: Origins of the EMF Cancer-Scare
The Normal Curve Cycle of Public Fear of Environmental Issues and its Effect on Property Values
EMF CANCER SCARE - CONTENTS: Origins of the worry that electromagnetic fields - EMF - might cause cancer in humans. What is the EMF Hazard? The normal pattern of rise and fall of public fear for most environmental hazards, real or imagined.
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Origins of public fear of electromagnetic fields or EMF exposure:
This paper discusses the origins & history of consumer, home owner, & home buyer concern that electromagnetic fields - EMF - might cause cancer in humans, the effect on house prices caused by cycles of public fear about potential, imagined, or real environmental hazards. As people become acclimated to a particular fearful topic it loses its initial shock value
Origins of Cancer Scare and Electromagnetic Fields
Realtors listing or owners selling a property which adjoins an overhead power transmission line know that there are sometimes
very significant marketing issues because of consumer concern for potential health issues where electric power lines
expose people to strong and continuous electromagnetic fields (EMF).
A lengthy US government review of studies of the health
effects of exposure to EMF concluded both that the actual level of risk was uncertain and that prudent avoidance of
significant EMF exposure was warranted.
A later Swedish study of the health effects of electromagnetic fields was able to overcome important difficulties in calculating
actual EMF exposure levels, and suggested that there was indeed some carcinogenic risk from EMF exposure.
The Swedish EMF study is
important: it established a "dose-relationship" between the amount of exposure and the frequency of leukemia. The
failure of other studies to demonstrate a specific dose-disease relationship has been used by utilities and government to
assert that there is no proven relationship and no proven risk associated with EMR.
If the public exposure to EMF has been present for a long time, what causes surges in public anxiety about this topic?
At times the release of cancer-risk studies regarding EMF and media focus on this topic have generated a cycle of public
fear about electromagnetic fields.
The enviro-scare cycle, in my opinion, derives from periodic surges of journalist and
media attention to studies of the carcinogenic effect of exposure to electromagnetic fields.
For example, there was
considerable media attention to Werth's observation that living along the Denver Colorado power line right-of-way caused
an EMF exposure which appeared to cause (or correlate with) a "doubling of the probability of childhood leukemia" for children living along the right-of-way of this overhead power transmission facility.
The concern for possible carcinogenic or "cancer-causing" effects of exposure to electromagnetic fields at the
frequency and strength generated by power transmission lines has been studied for some time.
Some contemporary research
(by epidemiologist Nancy Werth, the "Denver Study") suggested a possible (but in fact small) correlation between exposure
to 60 cycle electromagnetic fields (EMF) and the occurrence of leukemia in children.
Her study found that the occurrence
of childhood leukemia in the Denver Colorado area tended to cluster along and follow the path of a power distribution
line which passed through a portion of the city. (I've already mentioned the "study of studies" and the important
Swedish study above.)
Stating risk this way ("doubling the risk of childhood leukemia from power transmission line EMF exposure") is
understandably frightening to parents, particularly those unfamiliar with statistics and the mathematics of risk
As I will amplify below, if an exposure doubles a number which is at the start infinitesimally small, say 1
chance in 10,000, then the doubled number is still infinitesimally small, say 2 in 10,000.
A careful reading of the Werth
study or an interview with Werth herself would almost certainly yield a more cautious opinion about the level of
risk than that generated by a public reading of news reports.
But this analysis is not
comforting to everyone.
The more broad topic of public fear and assessment of the level tolerable health risk has been
widely discussed, and has as a component, the individual's assessment of the level of control that s/he has over the
risk. So people who smoke, an act which creates a far greater health risk than power transmission lines, assess that
risk as more moderate because they have a sensation of being able to "choose their poison."
Our own field measurements of EMF levels at residential properties or at specific locations within buildings
have found a wide range of levels of exposure to
building occupants. Remarkably, I've found that local ambient EMF levels in built-up residential areas are often quite
close to the (rather low) reaction threshold discussed in the Werth and other studies, even where no obvious overhead
electric power transmission facility is involved.
However when no large transmission facility is present, the strength of
the EMF drops much more rapidly with distance from the (smaller) sources of such fields.
The implications of this observation
and its accuracy merit further discussion and research since there could be small local sources in buildings which also
affect occupants. Some examples are listed later in this paper.
Both the difficulties of measuring actual EMF exposure
and the current level of knowledge about the health effects of EMF bear thoughtful discussion, some of which I address in
Electric utility workers who spend time repairing or installing power transmission lines and transformers probably have the highest exposure to electromagnetic fields.
Consumers researching the possible health effects of EMF exposure should look closely at these studies for both the study conclusions and the care (and lack of bias) with which such studies may have been performed.
Because various parties have conflicting interests, research and advice on this topic
have been confusing.
The interested parties include building owners and sellers, realtors, home buyers, power
transmission companies, journalists, and scientists or researchers who themselves are supported by various funding
sources. A new study of studies which tests for correlation between the interests of each funding
source and the results of studies performed would be a helpful test of conflicting opinions on this topic.
Articles About Electromagnetic Fields, Hazards, Measurements
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"Questions and Answers about Biological Effects and Potential Hazards of Radiofrequency Electromagnetic Fields", Federal Communications Commission, Office of Engineering and Technology, US FCC, OET Bulleting 56, 4th Edition, August 1999
" Many consumer and industrial products and applications make use of some form of
electromagnetic energy. One type of electromagnetic energy that is of increasing importance
worldwide is radiofrequency (or "RF") energy, including radio waves and microwaves, which
is used for providing telecommunications, broadcast and other services. In the United States
the Federal Communications Commission (FCC) authorizes or licenses most RF
telecommunications services, facilities, and devices used by the public, industry and state and
local governmental organizations. Because of its regulatory responsibilities in this area the
FCC often receives inquiries concerning whether there are potential safety hazards due to
human exposure to RF energy emitted by FCC-regulated transmitters. Heightened awareness
of the expanding use of RF technology has led some people to speculate that "electromagnetic
pollution" is causing significant risks to human health from environmental RF electromagnetic
fields. This document is designed to provide factual information and to answer some of the
most commonly asked questions related to this topic." - original source: U.S. Federal Communications Commission Office of Engineering and Technology, http://www.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oet56/oet56e4.pdf
"Magnetic Field Exposure and Cancer: Questions and Answers [ copy on file as /emf/EMF_Fact_Sheet_NCI_NIH.pdf ] - ," National Cancer Institute, U.S. National Institutes of Health, web search September 2010, original source: http://www.cancer.gov/cancertopics/factsheet/Risk/magnetic-fields
makes these five key points about EMF
Electric and magnetic fields (EMF) are areas of energy that surround any electrical device. EMFs are produced by power lines, electrical wiring, and appliances (see Question 1).
Electric fields are easily shielded or weakened by walls and other objects, whereas magnetic fields are not. Since magnetic fields are more likely to penetrate the body, they are the component of EMFs that are usually studied in relation to cancer (see Question 1).
Overall, there is limited evidence that magnetic fields cause childhood leukemia, and there is inadequate evidence that these magnetic fields cause other cancers in children (see Question 2).
Studies of magnetic field exposure from power lines and electric blankets in adults show little evidence of an association with leukemia, brain tumors, or breast cancer (see Question 3).
Past studies of occupational magnetic field exposure in adults showed very small increases in leukemia and brain tumors. However, more recent, well-conducted studies have shown inconsistent associations with leukemia, brain tumors, and breast cancer (see Question 4).
US Environmental Protection Agency, Office of Pesticides
and Toxic Substances, TSCA Assistance Office (TS-799), 800-424-9065
"Evaluation of Potential Carcinogenicity of Electromagnetic Fields,"
EPA Report #EPA/600/6-90/005B October 1990. EPA: 513/569-7562.
"Biological Effects of Power Frequency Electric and Magnetic Fields"
background paper, prepared as part of OTA's assessment of "Electric Power
Wheeling and Dealing: Technological Considerations for Increasing Competition,"
prepared for OTA by Indira Nair, M. Granger Morgan, H. Keith Florig, Department
of Engineering and Public Policy, Carnegie Mellon University, Pittsburgh, PA
"Biological Effects of Power Line Fields," New York State Powerline
Project. Scientific Advisory Board Final Report, July 1, 1987.
"Extremely Low Frequency (ELF) Fields," Environmental Health
Criteria 35. World Health Organization, Geneva, 1984.
"Electric and Magnetic Fields at Extremely Low Frequencies:
Interactions with Biological Systems. In: Non ionizing Radiation Protection,
World Health Organization, Regional Office for Europe, Copenhagen, 1987.
"Electric and Magnetic Fields from 60 Hertz Electric Power: What do
we know about possible health risks?," Department of Engineering and Public
Policy, Carnegie Mellon University, Pittsburgh, PA 15213 1989.
"Electromagnetic Fields Are Being Scrutinized for Linkage to
Cancer," Sandra Blakeslee, New York Times, Medical Science section, April
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