- A Tale of Two Studies:
- NAS/NRC Vs. NCRP
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- NAS/NRC report (1996)
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- On October 31st, the US National Academy
of Sciences, National Research Council
(NAS/NRC) issued a review of the EMF
literature; Possible Health Effects of
Exposure to Residential Electric and
Magnetic Fields. The conclusions of this
report are that there is no conclusive
and consistent evidence showing that
exposure to residential electric and
magnetic fields produces cancer, adverse
neurobehavioral effects, or reproductive
and developmental defects. Of significant
importance are the words,
"conclusive and consistent".
Like the more familiar phrase in law,
"beyond reasonable doubt",
"conclusive and consistent"
imply a certain standard of evidence that
warrants more serious action. Using that
standard of evidence, the NRC Committee
concluded that research results do not
show that EMF exposure at a residential
environmental level causes adverse health
effects.
-
- According to the newsletter EMF Health
Report, (Nov/Dec 1996) published by the
U. S. based Information Ventures:
"The findings to date do not support
claims that EMF's are harmful to a
person's health," said Dr. Charles
Stevens of the Salk Institute, who was
the chair of the NRC Committee that wrote
the report. The official NRC/NAS news
release headline states: "No Adverse
Health Effects Seen From Residential
Exposure to Electromagnetic Fields."
-
- As a result of this "not
guilty" verdict the US Department of
Energy (DOE) plans to stop all EMF
research in September 1998 and there is
the likelihood that the US House of
Representatives and the Senate will
drastically cut the budget for future US
EMF research.
-
- In the Electrical Supply Association of
Australia's (ESAA) newsletter EMF Update
of January 1987, it is reported: "In
an extensive review of the scientific
literature relating to the possible
health effects of exposure to residential
electric and magnetic fields the (NAS)
concluded that "the current body of
evidence does not show that exposure to
these fields presents a human-health
hazard" NAS appointed an expert
committee of 16 scientists to review 17
years of research (costing $500 million)*
in hundreds of studies on three
continents. The present report is the
result of that effort It (the NAS report)
is an important benchmark document in the
history of the EMF scientific debate
against which future research findings
will need to be viewed."
-
- Is the NAS/NRC report a conclusive
vindication for EMF's? The answer to that
question depends upon your viewpoint. If
you take a narrow legalistic
interpretation, such as DOE does, the
'not guilty' verdict may seen
appropriate, especially if you take into
account only the evidence considered by
the NRC Committee.
-
- However if you take a scientific
interpretation and consider all the
available evidence, the conclusion is
inescapable. So many scientific studies
were excluded from the
"extensive" NAS/NRC report,
that its conclusions cannot be considered
an accurate review of the current
scientific literature.
-
- In its review of the literature, the NRC
Committee restricted themselves to
considering only studies published in
peer-reviewed journals up to mid 1995,
when the report was drafted. This
excluded occupational studies such as the
Ontario Hydro worker study which found a
strong leukemia/EMF linkage (see page 4),
the recent Boston University study which
reported a link between female breast
cancer and EMF's , and the four
replicated melatonin/EMF studies, which
found low level commonly encountered
magnetic field exposures can reduce the
ability of melatonin to suppress breast
cancer cells (see page 5), just to
mention a few. In fact the NRC Committee
only considered approximately half the
available evidence which was available to
them. Dr. Kjell Hansson Mild of the
National Institute for Working Life in
Sweden, asked Dr Stevens, chair of the
NRC Committee, how "the report
turned out to be so biassed in its
selection of papers." Mild, past
president of the Bioelectro-magnetics
Society, noted that the report mainly
included papers that showed no effect and
omitted those that found a biological
response. (Microwave News, Jan/Feb.1997 .
P.2)
-
- In a clever manipulation of words, more
akin to an industry public relations
exercise, the NRC press release states
"To date, they have found no
evidence to show that EMF's 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 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."
-
- "To date" means a cut off date
of mid 1995 for peer reviewed and
published research, a process which can
take years, thereby conveniently omitting
the very studies which had results
opposed to the NAS/NRC report's own
findings.
-
- To be fair to the NAS/NRC report, the
meta-analysis of 11 residential
epidemiological studies was one of the
most thorough to date. What it did find
is that there is a reliable statistical
association between childhood leukemia
and power line proximity, as classified
by wire codes. As Dr. Richard Luben, NRC
committee member remarked, "The
level of association between power lines
and leukemia is roughly the same as the
correlation between second-hand smoking
and lung cancer".
-
- However, because the committee was
looking for conclusive evidence of a
connection with EMFs, it was able to
dismiss all data which failed to meet
this criteria and therefore could not
conclude EMFs were to blame. Epidemiology
looks for increases in risk factors, it
does not deal with conclusive proof. By
setting such an impossible standard the
National Academy of Science was able to
dismiss the EMF link with childhood
cancer and announce to the world that
there was nothing to worry about.
-
- The NAS press release also states,
"The committee also called for more
research into the relationship between
high exposures to EMF's 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 statement gives the
impression that there is no evidence that
EMF's affect melatonin in humans
-
- The NAS can only state this by ignoring
the four replicated melatonin studies on
human breast cancer cells (see page 5)
showing that a 50-60 Hz, 12mG magnetic
field can reduce melatonin's ability to
suppress breast cancer cells in vitro.
This was simply done because these
studies did not meet the NAS/NRC's strict
criteria for acceptance. As for further
evidence of an effect on humans from
human exposure studies, completed since
the NAS/NRC report was released, consider
the following:
-
- 1) A preliminary study of 60 workers at a
Finnish garment factory found a
"highly significant effect" of
EMF's in reducing nocturnal levels. (see
page 6)
-
- 2) In a study of 192 electric utility
workers, Drs. John Reif and James Burch
from Colorado State University found that
some EMF exposures are associated with
lower levels of melatonin. (page 6)
-
- 3) In a study by Swedish researchers, it
was found worker's levels of melatonin
decreased significantly after a day of
computer work, suggesting that
"there is a direct impact from the
electromagnetic environment of the [VDT]
on levels of melatonin. (page 6)
-
-
- *(This is a somewhat misleading
statement; 17 years of research may have
cost $500 million, but the NAS report
cost the Department of Energy (DOE), who
contracted the NAS to do the review,
$622,000.)
-
-
- NCRP draft report (1995)
- The U.S. National Council on Radiation
Protection and Measurements (NCRP), a
congressionally chartered organisation,
was contracted by the Environmental
Protection Agency (EPA) in 1983 to
conduct a review of the biological
effects of Extremely Low Frequency (ELF)
EMF's. Work was discontinued in 1986 due
to funding cuts at the EPA, but resumed
in 1991. In early 1995 the draft of the
800 page NCRP report was leaked to the
New York based publication Microwave
News, which published the report's
findings in August 1995. The final report
was supposed to be publicly available in
early 1996, but has received such intense
industry opposition to its findings that
its final outcome remains uncertain.
-
- The Committee's membership was described
by chairman Dr. Ross Adey as
"carefully selected to cover the
great majority of societal interests on
this scientific problem, including power
industry engineers, epidemiologists,
public health specialists as well as
molecular and cellular biologists.
"The draft report generally endorses
a 2mG exposure limit. It would
immediately effect new day-care centres,
schools and playgrounds, as well as have
implications for new transmission lines
near existing housing.
-
- A somewhat more flexible policy would be
applied to new housing and offices. For
existing facilities, the committee
recommended a more gradual approach, with
stronger restrictions phased in over time
if the evidence of a health risk
continues to grow.
-
-
- From the Committee's Conclusions
-
- "In arriving at the proposed
guidelines, the committee has considered
available laboratory studies on
bioeffects and epidemiological reports of
health hazards from electric and magnetic
field exposure In key areas of
bioelectro-magnetic research, findings
are sufficiently consistent and form a
sufficiently coherent picture to suggest
plausible connections between ELF EMF
exposures and disruption of normal
biological processes, in ways meriting
detailed examination of potential
implications in human health."
-
- From studies on humans the committee
cites evidence for a link between EMF's
and: 1) childhood and adult cancer,
including leukemia and brain cancer; 2)
teratological effects and other
reproductive anomalies; 3) neuroendocrine
and autonomic responses which, separately
or collectively, may have
pathophysiological implications; 4)
neurochemical, physiological, behavioural
and chronobiological responses with
implications for development of the
nervous system.
-
- From laboratory studies the committee
notes that EMF's: 1) effect cell growth
regulation in animal and tissue models in
a manner consistent with tumour
formation; 2) increase tumour incidence
and decrease tumour latencies in animals;
3) alter gene transcriptional processes,
the natural defence response of
T-lymphocytes and other cellular
processes related to the development and
control of cancers; 4) effect
neuroendocrine and psychosexual
responses.
-
- In relation to the effect of low level
EMF's on melatonin, (evidence which the
NAS/NRC report excluded) the committee
concluded: "There has been a strong
focus on ELF field actions in the pineal
gland, relating to the pineal hormone
melatonin, and on a broad series of
regulatory functions mediated by this
hormone. Melatonin plays a key role in
controlling the 24-hour daily biological
rhythm. Disturbance of the normal diurnal
melatonin rhythm is associated with
altered estrogen receptor formation in
the breast, a line of experimental
evidence now under study, or possible
links between ELF field exposure and
human breast cancer.
-
- "Further, melatonin has general
properties as a free radical scavenger,
with the possibility of a preventative
role in oxidative stress, recognised as a
basic factor in a broad spectrum of human
degenerative disorders, including
coronary artery disease, Parkinson's and
Alzheimer's diseases, and aging."
- According to the committee, problematic
sources of ELF EMF include local
electrical distribution systems, as well
as high voltage power transmission
systems. Particular appliances, including
electric blankets and VDT's also rate
highly as problem sources, along with
"various occupational
environments".
-
- The committee states that the evidence
points to human health hazards in common
exposures to EMF's, particularly magnetic
fields exceeding 0.2uT (2 milli-Gauss)
and electric fields at intensities in the
range 10-100V/m (volts per metre).
-
- "there is an implication that a
significant proportion of the world's
population may be subjected to a low
level or risk, but a risk factor with
significant societal consequences, by
reason of its pervasive nature and the
serious consequences for affected
individuals."
-
- NCRP interim exposure guideline
recommendations
-
- The committee concludes that
"neither laboratory studies nor
epidemiological findings can yet
establish well-defined thresholds for
safety guidelines." Still, it
contends: "From available
epidemiological and laboratory data, it
appears both prudent and responsible to
set limits on permissable future
exposures. Therefore it calls for
"interim exposure guides",
measures that "fall short of
establishing either a standard or
guideline, but offer guidance to limit
exposure."
-
- ALARA Policy Endorsed
- While the report notes that committee
members were not unanimous, it recommends
a policy in which exposures would be
"as low as reasonably
achievable", known as ALARA. Over a
three year period, ambient exposures in
existing homes, schools and offices would
be reduced to 10 mG. After six years,
there would be an option to establish a
guideline of 5 mG.
-
- Each of these decisions would be based on
whatever epidemiological and laboratory
studies were then available. After ten
years, a goal of 2mG would be considered.
The report stipulates that mitigation of
the existing EMF environment to this
level should be adopted only after
"a careful evaluation of its
socioeconomic impact, as well as its
cost-effectiveness."
-
- With respect to future construction, the
report recommends observing a 2mG
exposure limit for schools and for new
transmission lines near existing housing,
with somewhat less strict guidelines for
new housing and offices.
-
- Committee member Dr. David Carpenter, of
the School of Public Health at the State
University of New York, Albany, said,
"In almost any other type of
environmental exposures, if the evidence
were as strong as the association between
EMF's and cancer, there would be
extensive government regulation. The
major reason that many members of the
committee were unwilling to set more
rigorous standards was that it would be
horrendously expensive and unrealistic to
enforce them." (Microwave News,
July/Aug 1995)
-
-
- It must be pointed out that the NCRP
report is still in a draft form and as
such is has no official standing at this
time. Because of this there are many who
would prefer that this report be ignored
and that the NAS/NRC report be taken as
the definitive evaluation on the health
effects from exposure to EMF's. It will
be a sad day for science if a report
which can only arrive at its conclusions
by ignoring a significant body of science
is accepted as the definitive statement
on the issue.
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