Dominion is committed
to supplying electricity in a responsible and safe manner and this commitment
fully includes concern over possible health hazards from exposure to 60 Hertz
electric and magnetic fields. This commitment is supported by other independent
views throughout the scientific community.
The preponderance of evidence in the scientific literature
available to date for causation of cancer or any other deleterious effects
in humans from exposure to EMF from nearby high voltage transmission lines
is neither convincing nor consistent. The studies published in the literature
lack clear demonstration of a significant causal relationship and a definitive
dose-response gradient.
The National Research Council (NRC)
"Committee on the Possible Effects of Electromagnetic Fields on Biological
Systems" chairman Dr. Charles Stevens stated in a press release dated October
31, 1996, regarding the completion of a new report after the group examined
more than 500 studies spanning 17 years of research
The findings to date do not support claims that electromagnetic
fields are harmful to a person’s health. 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 EMF’s can damage the cell in
a way that is harmful to human health.
The NRC Committee to Review the Research
Activities Completed Under the Energy Policy Act of 1992 stated in a report,
Research on Power-Frequency Fields Completed Under the Energy Policy Act
of 1992, published in 1999:
We conclude that no finding from
the EMF-RAPID program alters the conclusion of the previous NRC review on
Possible Effects of Electromagnetic Fields on Biological Systems. In view
of the negative outcomes of EMF-RAPID replication studies, it now appears
even less likely that [E]MF’s in the normal domestic and occupational environment
produce important health effects, including cancer.
Specific EMF Questions
Q: What are the effects of EMF, and why does the
company take the stand that it is not harmful when there are no conclusive
results? Wouldn’t
it be more prudent and caring for the company to do whatever it took to eliminate
the possibility of harmful effects? A: For the
reasons cited above, we do not feel that EMF posed a health concern. (>
More)
Q: Are
trees effective screens for EMF?
A: Trees and common building materials
do provide a screen for electric fields, but they do not provide a screen
for magnetic fields. Both fields diminish over distance.
Q: How does a second circuit negate EMF readings
from a first circuit? Is this practice used widely in the electricity industry?
A: Dominion performed
magnetic field calculations of the existing facilities on the W&OD right-of-way.
Additional studies were performed to calculate magnetic field intensities
with the proposed transmission facilities included. These calculations also
follow accepted industry practices. Actual magnetic field measurements have
verified the accuracy of similar calculations on other facilities.
The results of these calculations
show magnetic field intensities at points off the right-of-way are slightly
reduced with the additional lines. This reduction is counter-intuitive, but
is reasonably easy to explain. In poly-phase electrical circuits, the peak
values of the current flowing in each conductor occur at different points
in time from each other. These current flows are responsible for generating
the separate magnetic fields. Since these current waveforms are out of phase
with each other, there are cancellation effects that naturally take place.
With multiple, poly-phase circuits, the physical layout of the various conductors
plays a significant role in the magnitude of the fields at points on and off
of the right-of-way.
For example, consider a three-phase
single circuit line with the conductors arranged in a vertical configuration
with the phasing "A, B, C" bottom to top. With this line operating
at peak current levels, a magnetic field of "x" milliGauss will
be observed at a distance of 50 feet. Add a second three-phase single circuit
line with the conductors arranged in a vertical configuration with the phasing
"A, B, C" bottom to top, adjacent to the first line. When operating
at the same peak current levels in the second line as in the first, the magnetic
fields at the same point 50 feet away from the first line will increase to
a level of "2x".
By simply rearranging
the phases on the second line to be "C, B, A", bottom to top, i.e., reversed
from the first line, the magnetic fields at the same point 50 feet away from
the first line will decrease to a level of "1/2 x". This reduction
is purely a result of the cancellation effects of the magnetic fields generated
by current peaks being out of phase with each other.
