Envtronnwttftf Board iA-101)
ft UlACUQfl t
AN SAB REPORT:
POTENTIAL
CARCINOGENICITY OF
ELECTRIC AND MAGNETIC
FIELDS
REVIEW OF THE ORD'S
BY THE RADIATION
ADVISORY COMMITTEE'S
NONIONIZING ELECTRIC
AND MAGNETIC FIELDS
SUBCOMMITTEE
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 204fQ
January 29, 1992
fiPA-SAB-RAC-92-013 ' ' " ' ' '' -
QFRCEQP
Mr, William K. Reilly, Administrator ncMMMnwoi
U.S. Environmental Protection Agency
401 M Street SW
Washington, DC 20460
Res Pote_nfc|g.A C?arej.nogenicity of filectromajmejtic Fields
Dear Mr. Reilly:
The enclosed is the report of the Nonionizing Electric and
Magnetic Fields Subcommittee of the Science Advisory Board's
Radiation Advisory Committee* The report has been endorsed by
the science Advisory Board on the recommendation of its Radiation
Advisory Committee.
The Subcommittee was set up in response to the October 12,
1.990, memorandum from the Directors of the Environmental
Protection Agency's offices of Health and Environmental
Assessment (William Farland), Health Research (Ren Sexton), and
Radiation Programs (Richard Guimond). The letter requested a
peer review of the draft report, Eyalujajblgn.- o_f—the Potential
Carcinogenicitv of Electromagnetic Fields (IPA/600/6-90/005B).
The Subcommittee met three times. Its first meeting, on
January 14-16, 1991, in Washington, D,C., elicited an uncommonly
strong public participation: over 200 people, 19 formal and
several informal presentations, and a lively debate between
Subcommittee members (sitting as a panel) and members of the
audience. Among the formal presentations were those made by
Congressman Frank Pallone (Dem.-New Jersey), Mayor J. Connors
(Scranton, Pennsylvania), Dr. D. N. Erwin of the United States
Air Force Arpntrong Laboratory for Human Systems, and Dr. Robert
Adair, sterling Professor of Physics at Yale University. At its
second meeti&g on April 12-13, 1991, in San Antonio, Texas, the
Subcommittee, received preliminary drafts prepared by its three
subgroups (on physics, biology, and epidemiology) and heard
invited presentations by biophysicist Dr. Arthur Pilla of Mt.
Sinai Hospital in Mew ¥ork City, biologist Dr. Russel Reiter of
the University of Texas Health Science Center in San Antonio, and
physiologist Dr. Asher Sheppard of the Pettis Memorial Veterans
Hospital in Loma Linda, California. At its third meeting, July
23-25, 1991, in Washington, the Subcommittee reviewed a draft of
the present report which was subsequently approved by mail
with some amendments.
Printed sn flecycW Paper
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The charge to the Subcommittee was to review the document as
to the accuracy and completeness of the information provided, as
well as th* interpretation of the scientific data. The EPA
document has serious deficiencies and needs to be rewritten. As
the result of many internal inconsistencies, it is often
difficult to tell what the EPA's position is when reading th*
Evaluation of the Potential Careinogfen^eitv of Electromagnetic
Fields. Portions of the draft lead to conclusions which are not
the conclusions stated elsewhere in the document* Such
inconsistencies appear not only between the body and the
executive summary, but also between different pages of the
document itself. ' ; "- —•••••
Consequently, the document requires a logical reorganization
and complete rewriting with particular attention to careful and
precise use of language. A simple editing of the present text
would not be sufficient. The Subcommittee consciously refrained
from providing a list of particular inconsistencies because it
does not want to mislead the EPA into believing that editing
alone will address the Subcommittee's concerns.
*
Six specific questions were posed in the charge to the :
Subcommittee. Before responding to these questions explicitly,
the Subcommittee feels it important to express its viewpoint on
three underlying scientific issues, concerning (a) epidemiology,
(b) biological effects, and (c) carcinogenicity. These issues
are critical for the understanding of scientific issues in
research regarding electric and magnetic fields and must be
addressed in any future EPA discussion, of the potential
carcinogenicity of electric and magnetic fields.
a. The Subcommittee concluded that some epidemiological
evidence is suggestive of an association between surrogate
measurements of magnetic-field exposure and certain cancer
outcomes, in such studies, the existence of confounders is
always a possibility, but since no common confounder has yet been
identified, the existing evidence cannot be dismissed. In the
absence of much better exposure information and an understanding
of which exposures are significant, no precise exposure-response
relationship has yet been adduced. This lack, together with
limited understanding of possible biological mechanisms, prevents
the inference of cancer causality'from these associations at this
time.
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b. The Subcommittee accepts that'Effects on some
biological systems have been shown to occur at moderate field
intensities. (An example of such effects is the well-documented
work on phosphenes.) However, the evidence for effects at very
low field strengths is not so widely accepted* Even if effects
on living systems at lower fields do occur, t'he assumptions
leading to estimations of physical constraints thought to
preclude effects on isolated small spherical cells without
ferromagnetic structures may not be applicable to larger cells, or
cell systems such as neurons or neuronal networks. Many
intervening steps must be clarified before the biological
phenomena so far shown can be taken as direct evidence of health
impairment or carcinogenesis in the human.
"e. The EPA document does not present a holistic model of
carcinogenesis within which the strength of .existing evidence
concerning the carcinogenic properties of electric and magnetic
fields can be assessed. The revised document should do so. Lew-
frequency electric and magnetic fields do not carry enough energy
to cause mutations directly. The Subcommittee recognizes that
the incidence of cancer might well be affected by an agent that *
does not produce mutations. The known influence of factors sucb :
as hormonal imbalance and nutrition on cancer promotion is an
example of epigenetic effects*
With respect to the Subcommittee's charge and the six
questions that were posed, the Subcommittee responds as follows.
1* Is the interpretation of the human and animal evidence
of carcinogenicity supported by the available information?
Currently available information is insufficient to conclude
that the electric and magnetic fields are carcinogenic. Some
human epidemiologic data report an association between surrogates
for electric and magnetic field exposure and an increased
incidence of some types of cancer, but the conclusion of
causality is currently inappropriate because of limited evidence
of an exposure-response relationship and the lack of a clear
understanding of biologic plausibility.
2, De*s the animal or biological effects information
provid* a basis for postulating that there is a human
hazard from exposure to extremely low-frequency fields
or either modulated or unmodulated radiofrequency
-radiation?
Some of the in vitro and in vivo data on unmodulated RF have
suggested the existence of mechanisms by which human health
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5. . la the Agency's carcinogen classification system
applicable to electromagnetic fields?
Nonionizing electric and magnetic fields should not be
classified under EPA's chemical carcinogenesis system because of
present "major uncertainties. • These involve an "incomplete
understanding of which aspects of field-tissue interactions give
rise to biological effects. "properties of the various electric
and magnetic fields such as phase angle, polarization,
transients, and frequency range nay contribute to .different
biological effects. For these reasons, the use of the EPA'a
classification scheme at this time would fee inappropriate and
confusing.
6* Does the information cited in the document support
the conclusion that there is not enough information to
designate specific values of magnetic field strength as
being hazardous to human health?
Yes, there is insufficient information to designate specific
values of magnetic-field strength that may be hazardous to human :
health, for two reasons,
a. There is insufficient evidence from the human
epidemiology data and from animal/cell experiments to
establish eause-and-effect relationships between low-
frequency electric and magnetic field exposure and
human health effects and cancer.
b. The precise nature of the environmental low
frequency electric and magnetic field potentially
related to human disease remains to be elucidated, in
addition to field strength, parameters such as the
time-varying nature of the magnetic fields and the
relevant time/exposure parameters need to be
determined.
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The Subcommittee also wishes to express two specific policy
recommendations that in its view follow inescapably from the
scientific recommendations.
POLICY SSCOMMENDAMON #lj The Subcommittee is unanimous
in its belief that the question of electric and magnetic field
effects on biological systems is important mnd exceptionally
challenging/ and that the Subcommittee's advice to the EPA should
be that the report should be rewritten,by EPA, and then re-
reviewed by the Science Advisory Board*
POLICY RECOMMENDATION |2i EPA should complete its
efforts with regard to RF electromagnetic fields (including
microwaves) and issue exposure guidelines independent of present
issues pertaining to lower frequencies. The current EPA report
inadvertently leads even the careful reader to conclude that the
potential careinogenicity of electric and,magnetic fields of ELF
(i.e., powerline) frequencies is the only—or at least the
principal—subject of concern with regard to nonioni^ing fields.
Such a conclusion would reinforce the skewed and somewhat
sensationalized picture presented to the public in recent years
by the news media and government agencies responding to this :
publicity. The report should therefore declare explicitly that "
the attention given to nonionizing electric and magnetic fields
derives in the first place from long-standing concern over the
hazards of RF (including microwave) radiation. EPA has expended
substantial resources on the study of such radiation over a
period dating back to the EPA's inception, and EPA should
complete its efforts directed toward the issuance of RF exposure
guidelines, RF fields present long-known and well-understood
hazards such as temperature elevation in tissue and heat stress
resulting from acute exposures against which users and the
general public must be warned and protected. Any published
exposure guideline should specifically identify the hazards from
RF exposure.
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The Science Advisory.-Board appreciates the opportunity to
review issues of this importance and looks forward to a written
responsetefroa the Agency concerning its schedule for revising the
Evaluation
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NOTICE •-•'•• "•
This report has been written as a part of the activities of
the Science Advisory- Board, a public advisory group providing
extramural scientific information and advice to"the Administrator
and other officials of the Environmental "Protection Agency. The
Board is structured to provide a balanced, expert assessment of
scientific matters related to problems facing the Agency. This
report has not been reviewed for approval by the Agency; hence,
the comments of this report do not necessarily represent the
views and policies of the Environmental Protection Agency or of
other Federal agencies. Any mention of trade names or commercial
products does not constitute endorsement or recommendation for
use.
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ABSTRACT
This review constitutes comments by an Environmental
Protection Agency (EPA) appointed subcommittee of seventeen
experts in twelve disciplines to review a draft, version of EFA's
report Evaluation of the .Potential carcinogenicitv of
Electromagnetic. JTields (EFA/600/6-90/0051) . The reviewers
suggest numerous changes in emphasis, coverage, and wording;
comment on some policy considerations; and conclude that the
draft report in effect will have to be rewritten if all of these
suggestions and comments are to be taken into account. The
Subcommittee also presents its conclusions on the substantive
scientific questions discussed in the EPA report,
Keywords: electric, magnetic, electromagnetic, cancer
11
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• August a V "1991
0. S. ENVIRONMENTAL PROTECTION AGENCY
SCIENCE ADVISORY BOARD
RADIATION ADVISORY COMMITTEE
NONIONIZING ELECTRIC AND MAGNETIC FIELDS SUBCOMMITTEE
ROSTER
Chairman
Dr. Genevievc M. Matanoski, The Johns Hopkins University
School of Hygiene and Public Health, Baltimore, Maryland
Vice Chajrjgajj
Dr. David V. Bates, Vancouver, CANADA •
MEMBERS
Dr. A. Karim Ahmed, Princeton, New Jersey
Dr. Patricia A. Huffier, University of Texas Health
Center in Houston, Houston, Texas
Dr. Craig V. Byus, University of California, Riverside,
California
Dr. Kelly H. Clifton, University of Wisconsin Clinical
Cancer Center, Madison, Wisconsin
Dr. John DiGiovanni, University of Texas, M. D. Anderson
Cancer Center, Smithville, Texas
Mr. William E. Feero, Electric Research and Management,
State College, PA 16804
Dr. Robert £'. Harris, School of Public Health,
University of North Carolina, Chapel Hill, North Carolina
Dr. Clark w. Heath, American Cancer Society, Atlanta, Georgia
Dr. Nan M, Laird, Harvard School of Public Health
Boston, Massachusetts
Dr. M. Granger Morgan, Carnegie-Mellon University,
Pittsburgh, Pennsylvania
111
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Dr. Mary Ellen O'Connor, University of Tulsa,Tulsa, Oklahoma
Dr. Donald A. Pierce, Oregon State University, Corvallis, Oregon
Dr. Charles Susskind, College of Engineering,
University of California, Berkeley, California
Dr. Bary M, Wilson, Battelle Pacific Northwest laboratory
Richland, Washington
Dr. Richard Wilson, Department of Physics
Harvard University, Cambridge, Massachusetts
DESIGNATED FEDERAL OFFICIAL
Mrs. Kathleen w» Conway
Science Advisory Board
U.S. Environmental Protection Agency
401 M Street, S.W., A-101F
Washington, D.C. 20460
STAFF ..SECRETARY
Mrs. Dorothy M. Clark
secretary, Science Advisory Board
U.S. Environmental Protection Agency
401 M Street, S.W., A-101F
Washington, D.C. 20460
IV
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1.0 EXECUTIVE SUMMARY
The charge to the Subcommittee was to review the document as
to the accuracy and completeness of the information provided, as
well as the interpretation of the scientific data. The EPA
document has serious deficiencies and needs to be rewritten. As
the result of many internal inconsistencies, it is often
difficult to tell what the EPA's position is when reading the
Evaluat_jgn_ef^the Potential^earcinoaenicitv of Electric and
Magnetic Fields. Portions of the draft lead to conclusions which
are not the conclusions stated elsewhere in the document. Such
inconsistencies appear not only between the body and the
executive summary, but also between different pages of the
document itself.
Consequently, the document requires a logical reorganization
and complete rewriting with particular attention to careful and
precise use of language. A simple editing of the present text
would not be sufficient. The Subcommittee consciously refrained
from providing a list of particular inconsistencies because it
does not want to mislead the EPA into believing that editing
alone will address the Subcommittee's concerns. T
Six specific questions were posed in the charge to the
Subcommittee. Before responding to these questions explicitly,
the Subcommittee feels it important to express its viewpoint on
three underlying scientific issues, concerning (a) epidemiology,
(b) biological effects, and (c) carcinogenicity. These issues
are critical for the understanding of scientific issues in
research regarding electric and magnetic fields and must be
addressed in any future EPA discussion of the potential
carcinogenicity of electric and magnetic fields.
a) The Subcommittee has concluded that some of the
epidemiological evidence is suggestive of an
association between surrogate measurements of magnetic-
field exposure and certain cancer outcomes. In such
studies, the existence of confounders is always a
possibility, but since no common confounder has yet
been identified, the existing evidence cannot be
dismissed. In the absence of much better exposure
"information and an understanding of which exposures are
significant, no precise exposure-response relationship
has yet been adduced. This lack, together with limited
understanding of possible biological mechanisms,
prevents the inference of cancer causality from these
associations at this time.
b. The Subcommittee accepts that effects on some
biological systems have been shown to occur at moderate
field intensities. (An example of such effects is the
well-documented work on phosphenes.) However/ the
evidence for effects at very low field strengths is not
so widely accepted. Even if effects on living systems
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at lower fields do occur,-the assumptions-leading to
estimations of physical constraints for effects on
'Isolated small spherical calls without ferromagnetic
.structures may not be applicable to larger cells or
c»ll systems such as neurons or newronal networks.
Many intervening steps must be clarified before-the
biological phenomena•so far. shown can be taken as
direct evidence of health-'impairment or earcinogenesis
in the human,
c. the EPA- document' does not present a holistic model of
carcinogenesis within which the strength of existing
evidence concerning the carcinogenic properties of
electric and magnetic fields can be assessed. The
revised'document should do so. .Low-frequency electric
and magnetic fields do not carry* enough energy to cause
mutations directly. The Subcommittee recognizes that
the incidence of cancer might well be affected by an •
agent that does not produce mutations. The known
. influence of such factors as hormonal imbalance and
nutrition on cancer promotion is an example of such •an -t
epigenetic effect. .
Response to the Charge
with respect to the Subcommittee's charge and the six
questions which it posed, the Subcommittee responds as follows.
1* Is the interpretation of the human and animal evidence
of carcinogenicity. supported by the available
information?
Currently available information is insufficient to conclude
that the electric and magnetic fields are carcinogenic. Hunan
epideraiologic data report an association between surrogates for
electric and magnetic'field exposure and an increased incidence
of some types of cancer, but the conclusion' of causality is'
currently inappropriate because of limited evidence of an
exposure-response relationship and the lack of a clear
understanding of biologic plausibility.
2. Does the animal or biological effects information
provide a basis for postulating that there is a human
hazard from exposure to extremely low-frequency fields
or either modulated, or unmodulated radiofreguency
radiation?
Some of the in...,vitro and in vivo data on unmodulated RF have
suggested the existence of mechanisms by which human health
effects, but not carcinogenicity, may be inferred.* Both
unmodulated and extremely low frequency,(ELF)-modulated
radiofrequency (RF) fields of sufficient intensity can give rise
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to thermal effects. Noivthermal biological effects also have been
reported in some animals exposed to RF fields* It is well
established that some in vitro and in__YJtYQ experiments on 1LF
have shown nonthemal biologic effects at fields of moderate
intensity, and there are some suggestive effects at lower levels.
Furthermore, ELF-modulated RF fields assumed to be nonthemal can
produce many of the biological effects of ELF fields alone.
Hypothetical constructs relating observed biological effects to
possible health effects (specifically, increased cancer risk)
have been delineated. However, there are at present insufficient
data on raany of the critical steps in the linkage to infer
causality on the basis of animal or cellular data.
3. Has the Agency properly evaluated the way in which the
findings on biological effects and field-tissue
interaction mechanisms affect the interpretation of the
human studies? .. _
No, the EPA has not evaluated how the findings on biological
effects and nonionizing field and tissue interaction mechanisms
relate to the interpretation of human studies. The strength of
epidemiologic data depends on identification of supporting *
evidence from in vitro and jji vivo data. This relationship has :
not been developed in the report. The critiques of studies of
biological effects are contained in the discussions of the
several chapters.
4. Is the choice of topics in Chapter 5 appropriate and is
the interpretation of the biological effects literature
as it relates to carcinogenesis supported by the
available information?
The heading of chapter 5, "Supporting Evidence of
Carcinogenicity," is inappropriate. The interpretation of the
biological effects in the in...,.yitro systems as presented by the
report does not make a case for Carcinogenicity. The
Subcommittee found a lack of balance in the analysis and
presentation of evidence in this chapter. Specific individual
experiments ,need critical review.
5* Is the Agency's carcinogen classification system
applicable to electromagnetic fields?
Nonionizing electromagnetic fields should not be classified
under EPA's chemical carcinogenesis system because of present
major uncertainties. These involve an incomplete understanding
of which aspects of field-tissue interactions give rise to
biological effects. Properties of the various electric and
magnetic fields such as phase angle, polarization, transients,
and frequency range may contribute to different biological
effects. For these reasons, the use of EPA's classification
scheme at this time would be inappropriate and confusing.
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6. Does the information cited in the document support the
conclusion that there is not enough information to
• designate specific values of magnetic field strength as
being hazardous 'to human health?
Yes, there is insufficient information to designate specific
values of magnetic-field strength that may be hazardous to human
health, for two reasons.
a. There is insufficient evidence from the human
epidemiology data and from animal/cell experiments to
establish eause-and-effeet relationships between low
frequency electric--and magnetic field exposure and
human health effects and cancer.
b. The precise nature of the environmental lov frequency
electric and'magnetic field potentially related to
human disease remains to be elucidated* In addition to
field strength, parameters such as the time-varying
nature of the magnetic fields and the relevant
time/exposure parameters need to be determined. *
The Subcommittee also wishes to express two specific policy
recommendations that in its view follow inescapably from the
scientific recommendations.
POLICY RECOMMENDATION #1: The Subcommittee is unanimous in
its belief that the question of electric and magnetic field
effects on biological systems is important and .exceptionally
challenging, and that the Subcommittee's advice to the EPA should
be that the report should be rewritten by EPA, and then re-
reviewed by the Science Advisory Board.
POLICY RECOMMENDATION 12; EPA should complete its
efforts with, regard to RF electromagnetic fields (including
microwaves) and issue exposure guidelines independent of present
issues pertaining to lower frequencies. The current EPA report
inadvertently leads even the careful reader to conclude that the
potential
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substantial resources on the study of such radiation over m
period dating back to the EPA's inception, and EPA should
complete its efforts directed toward the issuance of RF exposure
guidelines, RF fields present long-known and well-understood
hazards such as temperature elevation in tissue and heat stress
resulting from acute exposures against which users and the
general public must be warned and protected. Any published
exposure guideline should specifically'identify the hazards from
RF exposure.
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*•- ---x ••>*.. *.:u-*" ort^2-Q INTRQB0CTION - • -•***•
;•.•••.. ... ,,,-. , ,..,,, . .. -.,.--. ,,.. > • ,. ,,,.
2.1 Background
At th» request of the Environmental Protection Agency's
Office of Radiation Programs, the Office of Health and
Environmental Assessment prepared Evaluation of ti^e Potential
Carclnoaenicitv of Electromagnetic Fields, m January 1990, EPA
staff requested orally that the Science Advisory Board (SAB)
review this document. At its next meeting, in May 1990, the
SAB's Radiation Advisory Committee (RAC) responded by
establishing a Nonionizing Electric and Magnetic Fields
Subcommittee under the chairmanship of RAC member Dr. Genevieve
Matanoski, An earlier draft of the Evaluation was reviewed on
June 23, 1990, by a panel chaired by Dr. Richard Griesemer of the
National Institute of Environmental Health Sciences; this review
was not a Science Advisory Board review. .....
After wide consultation and consideration of more than 250
scientists, the Director of the Science Advisory Board selected
seventeen members for the Nonioniiing Electric and Magnetic
Fields Subcommittee: *
Dr. A. Karira Ahmed, Princeton, New Jersey
,Dr. David Bates,* University of British Columbia
Dr. Patricia A. Buffler, University of Texas Health Center
in Houston, School of Public Health
Dr. Craig V. Byus, Biomedical Sciences and Biochemistry,
University of California-Riverside
or. Kelly H* Clifton, Department of Human oncology and
Radiology, University of Wisconsin clinical Cancer Center
Dr. John DiGiovanni, Department of carcinogenesis,
M.D. Anderson Cancer Center
Mr. William E. Peero, Electric Research and Management,
State College, PA
Dr. Robert Harris, Department of Environmental Science and
Engineering, School of Public Health,
University of North Carolina
Dr. Clark He,ath, American cancer Society
Dr. Nan Laird, Department of Biostatistics, Harvard School of
Public Health
Dr. Genevieve Matanoski,** School of Hygiene and Public Health
The Johns Hopkins University
Dr. M. Granger Morgan, Department of Engineering and Public
Policy, Carnegie-Mellon University
Dr. Mary Ellen O'Connor, Psychology 'Department, University
of Tulsa
Dr. Donald Pierce, Department of Statistics, Oregon State
University
Dr. Charles Susskind, College of Engineering,
University of California-Berkeley
Dr. Bary Wilson, Battelle Pacific Northwest Laboratory
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Dr. Richard Wilson, Department of Physics, Harvard University
*Vice Chairman of the Nonionizing Electric and Magnetic
Fields Subcommittee.
**Chairman of the Nonionizing Electric and Magnetic Fields
Subcommittee.
On October 12, 1990, the Directors of the Office of Health
and Environmental Assessment, Health Research, and Radiation
Programs formally requested SAB review of EPA's Evaluation of
Potential Carcinogenicity of Electromagnetic Fields and a related
research agenda. (This memorandum is Appendix A.) The
memorandum contained the charge to the Subcommittee* (The charge
also appears in Section 2.2)
At its October 23-24, 1990 meeting, the Executive Committee
accepted a workplan for the SAB which included four Fiscal Year
1991 meetings of the Subcommittee to undertake, and complete its
reviews of the carcinogenicity and research agenda documents.
The Federal Register published a notice December 18, 1990,
announcing both the availability of the Evaluation of i^he
Potential Carcinoaenicity of Electromagnetic Fields and the first;
meeting of the Subcommittee. At the first meeting, January 14- :
16, 1991, in Washington, D.C., IPA staff and contractors briefed
the Subcommittee on the document, the public provided more than a
day of oral comment, and time was allotted for Subcommittee
discussion. Before adjourning, the Subcommittee formed into
three groups which would prepare papers for consideration by the
Subcommittee at its next meeting. These groups were:
Physics; Mr. Feero, Dr. Susskind,* Dr. Richard Wilson
Biology: Dr. Ahmed, Dr. Byus, Dr. Clifton, Dr. DiGiovanni,
Dr. O'Connor, Dr. Bary Wilson*
Epidemiology; Dr. Bates, Dr. Buffler, Dr. Harris, Dr, Heath,*
Or, Laird, Dr. Pierce
* Authored paper after discussion with group.
The Subcommittee met for the second time April 12-13, 1931,
in San Antonio, Texas. The Subcommittee considered three group
papers, heard three invited speakers (Dr. Russel Reiter of the
University of Texas Health Science center at San Antonio, Or,
Asher Sheppard of the Pettis Memorial Veterans Hospital in.Loma
Linda, California, and Dr, Arthur Pilla of Mt. Sinai School of
Medicine In Mew York City), listened to oral comment from three
members of the public, and appointed a writing group to prepare a
draft Subcommittee report for consideration at the Subcommittee's
July 23-25, 1991, meeting in Washington, DC. (This July meeting
also began the Subcommittee's review of the research agenda.)
During the course of its review, the Subcommittee received
almost a thousand pages of written public comment from about
three dozen individuals and organizations. The Subcommittee
listened to oral comment from about 40 individuals. There was
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some_;overlap, 'between those ..providing "oral' and""written public
comments. ••• ;•'"•'• • ":- >• -'"
The Subcommittee edited this report at the July 23-25, 1991,
meeting, subsequently approved it by mail, and forwarded it to
the Radiation Advisory Committee. The Radiation Advisory.
Committee addressed the Subcommittee report at its September 18-
20, 1991, public meeting and forwarded it to the SUB'S Executive
Committee to be considered at its October' '29-30, "1991, public
meeting. After approval by the Executive Committee and minor
editorial corrections as suggested by the 'Executive committee,
the report was transmitted to the Administrator of the
Environmental Protection Agency.
2.2 Charge to the Subcommittee
The Agency seeks the advice of the. Board on the
accuracy and completeness of the entire document and on
the question of whether the interpretation of the
available information reflects current scientific
opinion, in addition, we would "like the Board to
address the following specific issues!
1. Is the interpretation of the human and
animal evidence of carcinogenicity supported
by the available information?
2. Does the animal or biological'effects
information provide a basis for postulating
that there is a human hazard from exposure to
extremely low frequency fields or either
modulated or unmodulated radiofreguency
radiation?
3. Has the Agency properly evaluated the
way in which the findings on biological
effects and field-tissue interaction
mechanisms affect the interpretation of the
human studies?
4. Is the choice of topics in Chapter 5
appropriate and is the interpretation of the
biological effects literature as it relates
to carcinogenesis supported by the available
information?
5. Is the Agency's carcinogen
classification system applicable to
electromagnetic fields?
6. Does the information cited in the
document support the conclusion that there is
8
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not enough information to designate specific
values of magnetic field strength as being
hazardous to human health?
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3.0 REVTEW OF THE DOCDMEHT
3.1 Response to the Charge
The charge to the Subcommittee was to review the document as
to the accuracy and completeness of the information provided, as
well as the interpretation of the scientific data. The EPA
document has serious deficiencies and needs to be rewritten. It
is often difficult to tell what the EPA's position is when
reading the Evaluation due to many Internal inconsistencies.
Portions of the draft lead to conclusions which differ from the
conclusions stated elsewhere in the-documents-Such
inconsistencies appear not only between the" body and the
executive summary, but also between different pages of the
document itself.
Consequently, the document requires a logical reorganization
and complete rewriting with particular attention to careful and
precise use of language. A simple editing of the present text
would not be sufficient. The Subcommittee consciously refrained
from providing a list of particular inconsistencies because it
does not want to mislead the EPA into believing that editing 4
alone will address the Subcommittee's concerns. •
six specific questions were posed in the charge to the
Subcommittee, with respect to the Subcommittee's charge and the
six questions that were posed, the Subcommittee responds as
follows,
1. Is the interpretation of the human and animal evidence
of carcinogcnicity supported by the available
information?
currently available information is insufficient to conclude
that the electric and magnetic fields are carcinogenic. Some
human epidemiologic data report an association between surrogates
for electric' and magnetic field exposure and an increased
incidence of some types of cancer, but the conclusion of
causality is currently inappropriate because of limited evidence
of an exposure-response relationship and the lack of a clear
understanding of biologic plausibility.
?. Do«s the animal or biological effects information
provide a basis for postulating that there is a human
hazard from exposure to extremely low-frequency fields
or either modulated or unmodulated radiofrequency
radiation?
Some of the in...vitro and ijD_giy.o data on unmodulated RP have
suggested the existence of mechanisms by which human health
effects, but not carcinogenicity, may be' inferred. Both
unmodulated and extremely low frequency (ELF)-modulated
10
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radiofrequency (RF) fields of sufficient intensity can give rise
to thermal effects. Nonthermal biological effects also have been
reported in some animals exposed to RF fields. It is well
established that some in vitr^ and in viyg experiments on ELF
have shown nonthermal biologic effects at fields of moderate
intensity, and there are some suggestive effects at lower levels
Furthermore, ELF-modulated RF fields assumed to be nonthermal can
produce many of the biological effects of ELF fields alone.
Hypothetical constructs relating observed biological effects to
possible health effects (specifically, increased cancer risk)
have been delineated. However, there are at present insufficient
data on many of the critical steps in the linkage to infer
causality on the basis of animal or cellular data.
3. Has the Agency properly evaluated the way in which the
findings on biological effects and field-tissue
interaction mechanisms affect the interpretation of the
human studies?
No, the EPA has not evaluated how the findings on biological
effects and nonionizing field and tissue interaction mechanisms
relate to the interpretation of human studies. The strength of '
epidemiologic data depends on identification of supporting •
evidence from in vitro and in vivo data. This relationship has
not been developed in the report. The critiques of studies of
biological effects are contained in the discussions of the
several chapters.
4. Is the choice of topics in Chapter 5 appropriate and is
the interpretation of the biological effects literature
as it relates to carcinogenesis supported by the
available information?
The heading of chapter 5, "Supporting Evidence of
Carcinogenicity," is inappropriate. The interpretation of the
biological effects in the in vitro systems as presented by the
report does not make a case for carcinogenicity. The
Subcommittee found a lack of balance in the analysis and
presentation of evidence in this chapter. Specific individual
experiments heed critical review.
5 Is the Agency's carcinogen classification system-
applicable to electromagnetic fields?
Nonionizing electromagnetic fields should not be classified
under EPA's chemical carcinogenesis system because of present
major uncertainties. These involve an incomplete understanding
of which aspects of field-tissue interactions give rise to
biological effects. Properties of the various electric and
magnetic fields such as phase angle, polarization, transients,
and frequency range nay contribute to different biological
11
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effects. For,these reasons, the use of EPA's classification
scheme at this time would be inappropriate and confusing,
-. , 6. Does the information cited in the document support the
conclusion that there is not enough information to
designate specific values of magnetic field strength as
,-••• being hazardous to human health?
Yes, there is insufficient information to designate specific
values of magnetic-field strength that may be hazardous to human
health, for two reasons.
a. There is insufficient evidence from the human.
epidemiology data and from animal/cell experiments
to establish unequivocal cause-and-effeet
relationships between low frequency electric and
magnetic field exposure and human health effects
•and cancer.
b. The precise nature of the environmental low
frequency electric and magnetic field potentially *
related to human disease remains to be elucidated. :
In addition to field strength, parameters such as
the time-varying nature of the magnetic fields and
the relevant time/exposure parameters need to be
determined.
3.2 Comments on the Executive Summary
The executive summary of Potentiaj^.jgaffcjiioqenicitv of
ElectroinaLgflgJt-i-C._F.i.eldg is not adequate. Special care should be
taken to ensure that it reflects the contents of the revised
freport exactly, without drawing any conclusions not substantiated
by the body of the report. Not a few readers (and post news
sredia) are sure to give only cursory attention to the full 366-
page text and to depend'for the gist of it on the executive
summary, so special care must be taken to make it.readable and
accurate*
3.3 Comment* on Chapter 2
3*3.1 Eloctric and Magnetic Fields and Mechanisms for
Biological Interactions
Chapter 2 attempts to do four things: describe the physical
characteristics of electromagnetic fields? explain how fields
couple with the body; quantify ambient exposuresi and discuss
mechanisms of biological interactions, A comprehensive treatment
of these four areas would constitute a book-length text. The
authors have compounded their difficulties by attempting to make
the presentation relevant to the entire range of frequencies,
12
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from ELF to microwaves. Trying to present all the above in less
than forty pages was destined to result in a superficial and
spotty treatment. The authors should reduce their scope to a
more manageable level by emphasizing the lower-'frequencies, for
which guasi»tatic analysis is appropriate. The report should not
attempt to teach field theory. Instead, it should present
material toward the physical, understanding needed in later
chapters. Simplified but logical and correct relationships mist
be drawn from the large body of Knowledge that encompasses the
theory of electricity and magnetism, together with the second law
of thermodynamics. In particular, relationships of charges,
forces, motion, and time rates of change should be presented for •
simple situations. It is an assumption, not yet disproved, that
they also apply to more complex (biological) situations. The
difficulties lie in calculating such complex situations and
knowing the boundary conditions.
The draft report separates electric and magnetic fields
according to frequency, but the way in which these fields are
likely to differ is poorly described. The following' should be
highlighted,
>
a) Ionizing frequencies (e.g., gamma and x radiation): the
product hf (PlancJc's constant times frequency) is above
the ionization threshold, so that ionization and
destruction of a simple cell are possible (even at low
intensity, although with correspondingly lower
probability).
b) High nonionizing frequencies (e.g., microwave and other
radiofrequency radiation): hf is below threshold and no
ionization takes place, but both electric and magnetic
fields penetrate insulating and partially conducting
bodies and can produce heating, as do microwave ovens,
c) Extremely low frequencies (e.g., powerline
frequencies): electric fields are strongly attenuated
in partially conducting bodies. The electric field E
in such bodies derives primarily from changes in the
magnetic field B, according to the equation
curl E = -*9B/Bt, or in words, the spatial rate of
change of the vector 1 equals the negative of the time
rate of change of the vector B, so that it is not alone
the magnitude of the magnetic field that is important,
but also the rate at which it changes with time.
The draft report lacks a discussion of the actual parameters
of the total electromagnetic fields that are likely to be
important for subsequent chapters. There is no recognition that
the effects on a system of charges (including the human body) are
in forces, as summarized by the Lorenz force law
13
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F - q(E + v x B), where v is the velocity vector and q is the
charge? or in words, that the force consists of two components-
(1) the product of charge and electric field, and (2) the product
of charge and velocity times the magnetic field and sine of the
angle between them. This point is not made in the draft report.
There are many implications.
Under some circumstances charges in some bodies act
coherentlyi this provides one potentially promising route for
investigating mechanisms of biological interactions with electric
and magnetic, fields. Another route for investigation is the
existence in biological tissues of permanent magnets, such as
those found in some soil microorganism and in honey bees. In
some circumstances these magnetic structures appear important to
living organisms; however,, there has not been systematic
investigation of the prevalence of such structures or their
importance.
3.3.2 Exposure....: . ,..„„. .. ^ ...... , ._. ....
in the discussion of epidemiology, all mention of exposure
is couched in the vague terms of "electromagnetic fields" or ev«i
"magnetic fields." The EPA's Human Health Assessment Group :
normally relates cancer incidence to a long-term average of some
exposure parameteri Although that may be appropriate for most
cancer-indue ing agents, the averaging time may well be shorter
for an agent that increases cancer in a new way. However, if
there are risks, it is not clear which parameters of electric or
magnetic fields will be the important ones. It is appropriate
for the report to focus on the time-integrated exposure (or dose)
metric, but it is important as well that other parameters be
adequately treated.
which critical parameter of the magnetic-field intensity H
should be discussed? It could be dH/dt (the time rate of change
of H), or dH/dt above some threshold applied randomly or in some
particular sequence over some period of time. It could be
JH(t) dt (the integral or sum of H over a time t), as implied by
the draft report? or the amount above a threshold Hc,_
\[H(t) - H } dt,* or the amount with a saturation H_, JH(t) dt
^(for H < Hm) andjH(t) dt +J5 dt (for H > H_). ft may not t
f ^ ^ ft ^ t* *l rfH, ^m db_ _ %*_«» « 1 *l i bk ^^.^ __ ._ — _^^_ ^^i__._ ^ __ , _» * ^? __*_ __» *_•_
feasible t&'be ali-inelusive,sbut some disculsion~of""the
plausible possibilities is recommended.
The report also fails to discuss background fields other
than fluctuations, if we accept there is no new force, the
exposure parameter is E + v x B; and inside the body,
curl E = -^B/dt. One of the principal contributions to
background exposure comes as we move with a velocity v through
the earth's magnetic field B. For many of us, this component is
vastly increased when v is the velocity of an aircraft. Yet the
draft report is written as if the only background of importance
14
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were the ambient SO-Hz field. That is clearly wrong and should
be corrected. And of course this varying background is a source
of confusion in any epidemiological study in ways that the draft
report fail* to discuss. , .»,.,,.- .
3.3.3 Models
The rather extensive discussion of models in the report
should be reduced to a tabulation of the prevalent hypothesized
models, with reference to when each was introduced and to what
extent attempts to explain experimental findings by each have
been successful. The strengths and weaJcnesses identified in the
literature should be tabulated. For example, the cyclotron-
resonance model has been criticized on two counts in a simple
paper by John Sandweiss (Bioelectromaemeti,gg llj 203-205, 19§o) :
(l) the cyclotron radius at the assumed field exceeds the size of
the object, yet several revolutions inside are needed to get a
resonance,* and (2) the mean free path of an 'electron in the
medium is so short that no resonance seems possible—a problem to
which reference is made, but whose fundamental nature is not
brought out.
3.3.4 Fluctuations -
A graph on p. 2-15 of the draft report shows the current
densities at which biological effects are expected, as well as
the noise fluctuations. There are other papers on fluctuations,
A recent publication by Robert Adair in the Physical Review (A43:
1039-1048, 1991), which also served as the basis of his
presentation at the Subcommittee's 15 January 1991 meeting, is a
good summary of the apparent points of conflict between the
biological effects attributed to weak electric and magnetic
fields and the constraints of known physical principles.
If a finding is repeatable but not explainable by existing
physical theory, it must be clearly labeled as such.
Hypothesized mechanisms in such cases are desirable and should be
presented. However, they must be discussed in terms of strengths
and weakness.es in predicting the observed phenomena, and the
points at which they do not fit present understanding. For
example, the calculation of thermal noise in a single cell would
prove to b* inapplicable if it could be demonstrated that the
bodies under consideration are not isolated cells but
agglomerations of cells of substantially larger dimensions than
individual cells, so that calculations based on single cells
would have to be revised? or if ferromagnetic materials are
involved, An additional point is that biological systems are
inherently nonlinear in hierarchies that extend from molecules to
cells, to tissues, and finally to organs and organ systems, so
that appropriate physical models must account for nonlinear
behavior, as well as noneooiilibrium physical characteristics,
commonly seen at the atomic level rather than the molecular.
15
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3.4 Comments on Chapter 3
3.4-1 Comments
The Subcommittee feels that the report's discussion of
epidemiologie findings is •• seriously deficient, given the central
importance of -'such data in evaluating possible human health risles
in.this perplexing field. Extensive revisions are therefor®
necessary both' in. chapter 3 and in 'the report * s summary and
Conclusions'. Although the EPA report achieves nearly couplet®
coverage 'of pertinent epidemiologic work- published through 1989
and properly approaches workplace exposures separately from
residential exposures, the manner in which these data are
described and-''evaluated is inadequate-In major respects.
a) In general, the report's review 'and analysis of
epidemiologic findings is unfocused-and diffuse. Its
writing is often repetitive and imprecise, and
descriptions of data are frequently mingled with
'interpretative comments. '-As a 'result, -the report lacks
cohesiveness, is difficult to read, and loses -
effectiveness in communicating its findings and *.
conclusions. :
b) The manner in which studies are reviewed is uneven.
Some studies are clearly less substantial than others,
yet they often receive equal or greater attention.
Discussion of findings includes too much unwarranted
speculation about causal interpretation, often such
speculation appears unbalanced, giving emphasis to
positive findings while de-emphasizing negative ones.
c) The critical inportance of exposure assessment does not
receive sufficient attention, particularly in relation
to surrogate measures and to potential
misclassification.
<3) In evaluating individual studies, and then reaching
conclusions for the field as a whole, the report fails
to focus coherently on the major epidemiologic issues
that ultimately shape any assessment of risk. In
addition to exposure assessment, these issues
particularly involve ability to discern exposure-
response relationships, to make precise measurements of
risk levels, and to evaluate the potential influence of
confounding variables. The report greatly needs to
address these particular issues in an organized and
critical manner.
16
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3.4.2 Reconmendat i ons
a) Chapter 3 should be extensively re-worked.
Major consideration should be given to full
published studies or studies in which manuscripts have
received peer review and are in press. Data presented
in abstract form, as letters to journals, or as case
series anecdotes should be clearly labeled as such.
Where other data deserve review (such as the recent
work by Peters et al.), their pre-publication nature
should be recognized.
The Subcommittee suggests focusing detailed
discussion of findings on the several studies of
greatest importance and, in those instances, perhaps
not exceeding three or four pages..each. Other studies
(abstracts, letters, etc.) could be summarized more
briefly. An appendix might be used if it seems
necessary to include extensive detail,
b) Coverage of the literature should be extended through '
1990, and beyond as available, especially with respect :
to the study by Peters et al. The 1989 Coleman et al.
study (Brift jTf Cancer) deserves fuller consideration,
as does information suggesting a role for traffic
density as a confounding factor.
c) A succinct summary table displaying only key findings
(Note; There is a "summary table" on pp. 3-127 to 3-
131 of the EPA's October 1990 document.) and
limitations in major studies may help to focus the
assessment and might become a nucleus for formal meta-
analysis of data. It nay also be useful to construct
graphs that display odds ratios and confidence
intervals for various population/exposure comparisons
in major studies.
d) It. may be useful to compare data across studies in
relation to cancer site, e.g., risks observed for
childhood cancers as a whole as opposed to leukemia or
central nervous system tumors in particular.
e) Throughout the report, special care should be taken to
avoid gratuitous speculation or surmise which may favor
either negative or positive interpretations of data
beyond the actual limits of those data. The
conservative intent of the report can only benefit by
evenhanded caution and careful precision in its
wording.
17
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3.4.3 Exposure Assessment-.;->>* •-•'- w •- .
A separate, expanded section should be developed addressing
issues of exposure assessment. Such a section should
particularly discuss the value and limitations of exposure
surrogates, gradients, and models in relation to epidemiologic
investigations. ^iTi
a) gxposure Surrogates. The "use of surrogates for
exposures, particu^arly^for pasfrmnmeasured exposures,
_ is not uncommon.in'occupational epidemiologic studies.
The use of wire codes in community studies, as done in
the tfertheimer, Savitz, and Peters studies,, ;ls
...... appropriate and defensible. g?hV use of surrogates may
very well result in less misclassification than occurs
when inherently variable spot present-day measurements
are used to represent unmeasured average exposures that
occurred in past years.
b) Exposure Gradients« A gradient in exposures of study
subjects is necessary in environmental or occupational.
epidemiologic studies. The choice of cut-points in
dichotomous or multistage exposure classifications may :
influence the results of statistical analyses. This
matter may deserve some summary comment relative to
reported studies.
c) Exposure Models. Use of exposure models may be
superior to the direct use of exposure measurements for
current exposures. Exposure models based on available
historic information that can be validated by use of
current measurement data are particularly useful for
studies dealing with past unmeasured exposures. Wire
code surrogate data have been indexed to magnetic field
levels in a relatively unsophisticated approach to
modeling. Progress is being made in this area (H. R.
Plynn et al., "Validation of expert judgment in
assessing occupational exposure to magnetic fields in
the utility industry," Appl. Occup. Envj,ro^,_^Hvq. 6:
141-145, 1990). Exposure modeling has been addressed
in the course of the Peters study and one hopes this
tt£il be discussed in the forthcoming publication of the
work.
3.4.4 Criteria for Assessing Significance of Data
The revised report should summarise the epidemiologic and
statistical principles that govern the report's assessment of
epidemiologic data. Such a section should include both
methodologic aspects and interpretive considerations and should
apply those principles to the overall evaluation of epidemiologic
evidence in this field.
18
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Important methodologic topics useful for assessing
individual studies include how a study measures exposure (extent
of exposure miselassification), how subjects are selected to
insure comparability, how potential confounding variables are
addressed, choice of statistical measures, and considerations of
study size and power. Criteria for interpretation of results in
the field as a whole include consistency among different studies,
strength of association, degree of evidence for exposure-response
relationships, and potential clinical specificity.
Also important for assessment of epidemiologic data is
consideration of the biological plausibility of epidemiologic
findings in relation to findings from other research disciplines.
Although the Subcommittee did not directly address this larger
issue in detail, the Subcommittee does recognize the critical
importance of such issues in reaching a valid assessment of
possible cause-effect relationships between.nonionizing-radiation
exposures and human cancer. Such considerations will ultimately
need to balance the strengths and weaknesses of epidemiologic
findings in relation to the strengths and weaknesses of evidence
in allied disciplines (experiments in animal toxicology, in
cellular and molecular systems, and in the physics of nonionizing
radiation).
3.5 Comments on Chapters 4 and 5
3.5.1 Overview
Both chapters mix review and evaluation in an inappropriate
manner. Studies should first be suTOnarized objectively. They
should then be evaluated in a discussion that covers both strong
points and weaK points.
Biological and potential health effects from 1LF exposure
now constitute an active area of research. The report should be
updated to include data that have become available since the
release of the present draft.
ELF and. RF data should be presented and discussed in
completely separate sections of the report, with comment and
conclusion* provided separately for each frequency range. •
However, wb,*re both ELF and RF are present (e.g., ELF-modulated
RF; ELF transmission lines carrying or picking up RF), such data
should be presented and discussed under both headings.
The summary tables included in the chapters were helpful,
Such tables should be expanded and updated to reflect recent
research findings.
From the information presented in chapters 4 and 5, it is
clear that hypothetical constructs relating observed biological
effects to possible health effects (specifically, increased
19
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cancer risk) can toe delineated. ^.However, there are insufficient
data on many of the critical steps'in the linkage to infer
causality on, the basis of animal oy eelluJ«.ar data*
3.5.2 Comments on Chapter 4
This chapter deals with biological effects observed in
animals exposed to electric and magnetic fields in the ELF range
and to RF fields assumed to be nontharmal. " ' '
7" Taken as a whole, 'animal 3ata reviewed and discussed in this
chapter, together with data from moire .recent animal experiments,
strongly suggest (and in some instances can, be said to
demonstrate) that ELF magnetic and electric fields are capable
of eliciting biological effects*
The distinction between biological effects and health
effects is an important one. It is especially relevant in the
context of, .the question of possible health .effects from, electric
and magnetic field exposure. ' The report must be precise in
distinguishing between these two concepts and carefully guard ,
against the tacit assumption that the observation of one !
(biological effects) automatically implies that the other (health
effects). exists.
in response to the specific charge to the Subcommittee to
comment on the value of animal data in Interpreting human
epidemiologic studies, the Subcommittee believes that the animal
data provided are not easily applied to the interpretation of
results from human epidemiologic studies for the following
reasons:
a) There are few data from different laboratories that
demonstrate consistent biological effects using the
same experimental protocols. However, newly published
information is emerging that will address this
shortcoming.
b) There have been no lifetime animal studies in which
carcinogenesis was specifically investigated as a
consequence of magnetic-field or electric-field
exposure.
c) With few exceptions, animal studies were not directed
at testing of a specific model or hypothesis relevant
to possible mechanisms of electric and magnetic field
effects in biological systems.
d) There is insufficient evidence of linear or
monotonically increasing exposure response from the
animal studies reviewed, and where response is linked
20
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to exposure (or dose), the effects appear to be "all or
none11 above some threshold,
e) Fi*ld intensities used in the experiments reviewed vary
widely and are often above those commonly encountered
by humans.
3.5.3 Comments on Chapter 5:
The title of Chapter 5 should be changed. The studies
reviewed and cited should not be presented as "supporting
evidence for carcinogenicity." The report, in fact, reviews data
that are relevant to and consistent with the hypothesis that
electric and magnetic fields may increase cancer risk, A
positive lifetime carcinogenicity study would constitute
supporting evidence. Such a study has not yet been done. In
fact, this chapter deals with potential mechanisms of interaction
of electromagnetic fields with biological systems. The revised
report should make it clear that these cellular effects can only
establish relationships and mechanisms of interaction.
In view of the testimony to the Subcommittee regarding the *
theoretical (mainly therpodynamic) constraints on biological "'
effects of low-frequency low-intensity fields, Chapter 5 should
include a discussion of the underlying assumptions regarding
size, structure, and conductive and dielectric properties of the
biological systems (cells, organs, or whole animals) under
consideration. The lumped transmission line model for signal
detection in collections of cells as presented to the
Subcommittee in testimony by Dr. Arthur Pilla, for example, may
serve as such a set of assumptions. These should be contrasted
with the assumptions used by Dr. Robert Adair in his recent
Physical .Review paper (A43; 1039-1048, 1991),
EPA should consider deleting discussion of data on electric
and magnetic field exposure of plant cells, but adding the
voluminous results available in connection with electric and
magnetic field stimulated bone repair.
Not mentioned in this document is the lack of effects
reproducible among laboratories, and lack of agreement or
understanding of what constitutes'exposure or dose. Until there
is progres* in these two areas it will remain impossible to
summarize the results of this field in a manner that will
approach "a consensus viewpoint."
A carefully worded statement regarding the difficulty of
some of the assay techniques should be included in this chapter.
Training in one aspect of biological assays may not qualify one
to conduct an assay on another system.'Many laboratories have
reported failure to replicate a result when in fact the
laboratory lacked the necessary expertise to conduct the assay
21
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appropriately. Conversely,.,a laboratory may report positive
results because it lacks the necessary expertise to carry out
reliable experiments.
A number of studies are presented dealing with DMA/field
interaction. No effects were found on breakage of strands or
repair of damaged strands. There is no evidence that genetic
mutations are induced by ELF electromagnetic fields. However,
effects cf ELF magnetic fields on gene transcription and
translation have been reported.
EPA should carefully review epigenetic factors in cancer
risk. Such factors include possible effects on:
transcription/translation, hormonal effects, and effects on the
immune system.
Fairly small fields have been reported .to..alter the flux of
calcium ions across cell membranes. Although some of the jjj
Xi£.£o calcium efflux data are open to concern about experimental
design and physiological interpretations, these effects appears
to be characterized by "windows" in frequency and intensity.
Although lower in amplitude, this alteration in calcium ion flux*
appeared in the same direction as changes caused by known cancer
promoters. An important consequence of altered calcium flux
would be a change in production of parathyroid hormone and
ornithine-decarboxylase.
Melatonin is a hormone with important regulatory functions.
A number of experiments have shown correlation between breast
cancer and decreased melatonin production. Exposure of rats to a
variety of low-strength electric and magnetic fields has been
shown to decrease melatonin levels in blood and pineal gland.
-**
The melatonin data are an important reason for recognizing
the existence of biological effects due to electric and magnetic
fields. It is not clear, however, that melatonin changes lead to
health effects. Although the phenomena are well described in the
report, they should not be presented as "supporting evidence of
carcinogeniQity." More recent data on breast cancer and prostate
cancer in males should be included in the melatonin discussion,
because increased risk for these specific cancers was
hypothesized on the basis of the melatonin findings.
References that are missing include the Gabriel et al. paper
and the Heltz references that were supplied to the subcommittee
by Dr. Martin L. Meltz. This chapter (or the mechanism chapter)
should include mention of the work of Dr. James C. Weaver and
Dr. R. Dean Astumian. The work of C. A. L. Bassett and others on
pulsed electromagnetic field (PEMF) treatment of bone is also
pertinent (see, for example, C. T. Brighton and S. R. Pollack,
Eds., Electromagnetisjn_jja_Mediej.ne and Biology. 1991).
22
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In summary, the Subcommittee believes the following;
a) The EPA's interpretation of the human and animal
evidence of earcinogenicity is not supported by data
available in the literature.
b) Biological effects and health effects must be'clearly
distinguishedi and although there may now be
hypothetical constructs for linking observed biological
effects to cancer risk, there is insufficient basis
from animal and cellular data for postulating human
cancer risk from exposure to ELF electric and magnetic,
fields.
c) In part because of insufficient data, EPA has not
properly evaluated the ways in which proposed
biological mechanisms of electric-.and magnetic fields
may affect interpretation of human data. However, the
melatonin findings as they relate to male breast and
prostate cancer, and other work on DMA transcription
leading to enhanced growth, may constitute findings
from which biological mechanisms to assist in *
interpretation of human data may eventually be :
developed.
d) The title for Chapter 5 is misleading and should be
changed; although the topics discussed in Chapter 5 are
relevant to the issue, the underlying assumption of
the existence of increased risk is disturbing*
e) The data presented in Chapter 5 do not constitute
supportive evidence for carcinogenic effects of
electric and magnetic fields in humans and animals.
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4.0 ADDITIONAL COMMENTS OH THE SCIENCE
The Subcommittee's mandate was to review the EPA report
answer specific «|uestions in relation to it. In view of "the
opportunity that the Subcommittee.had during its Amiiberations to
hear testimony and discussions .regarding.the 4ssue of any risk
associated with ELF., in the brief sections that follow, the
Subcommittee gives a summary of its collective response to what
it has identified as substantive questions. Until these questions
have been answered, no opinion can be advanced on the possibility
1 of a relationship between ELF and human disease.
The Subcommittee 'of 17 individuals represented expertise in
twelve disciplinary areas: biostatistics, engineering,-
epidemiology, experimental biology, exposure assessment,
medicine, neuro-endocrinoiogy, physics, physiological psychology,
radiation oncology and earcinogenesis, risk analysis and
toxicology. The breadth of opinion and diversity of view within
the Subcommittee would likely be replicated by any other group
with a correspondingly wide spectrum of expertise.
The Subcommittee feels it important to express its viewpoint?
on three underlying scientific issues, concerning (a) !
epidemiology, (b) biological effects, and (c) carcinogenicity.
These issues are critical for the understanding of scientific
issues in research regarding electric and magnetic fields'and
must be addressed in any future EPA discussion of the potential
carcinogenicity of electric and magnetic fields.
a) The Subcommittee has concluded that the epidemiological
evidence is suggestive of an association between
surrogate measurements of magnetic-field exposure and
certain cancer outcomes. In such studies, the
existence of confounders is always a possibility, but
since no common confounder has yet been identified, the
existing evidence cannot be dismissed, in the absence
of much better exposure information and an
understanding of which escposures ;-are significant, no
precise exposure-response relationship has yet been
adduced. This lack, together with limited
understanding of possible biological mechanisms,
prevents the inference of cancer causality from these
associations at this time.
b) The Subcommittee accepts that effects on biological
systems have been shown to occur at moderate field
intensities. (An example of such effects is the well-
documented work on phosphenes.) However, the evidence
for effects at very low field strengths is not so
widely accepted. Even if effects on living systems at
lower fields do occur, the assumptions leading to
estimations of physical constraints for effects on
24
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isolated small spherical cells without ferromagnetic
structures may not be applicable to larger cells or
cell systems such as neurons or neuronal networks.
Many intervening steps must be clarified before the
biological phenomena so far shown can be taken as
direct evidence of health impairment or carcinogenesis
in the human.
c) The EPA document does not present a holistic model of
carcinogenesis within which the strength of existing
evidence concerning the carcinogenic properties of
electric and magnetic fields can be assessed. The
revised document should do so. Low-frequency electric
and magnetic fields do not carry enough energy to cause
mutations directly. The Subcommittee recognizes that
the incidence of cancer might well be affected by an
agent that does not produce mutations. The known
influence of factors such as hormonal imbalance and
nutrition on cancer promotion is an example of
epigenetic effect.
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5.0 Policy Recommendations
The Subcommittee also wishes to express two specific policy
recommendations that in its view follow inescapably from the
scientific recommendations.
POLICY RECOMMENDATION fl: The Subcommittee is unanimous in
its belief that the question of electric and magnetic field
effects on biological systems is important and exceptionally
challenging, and that the Subcommittee's advice to the EPA should
be that the report should be rewritten by EPA, and then re-
reviewed by the Science Advisory Board.
POLICY RECOMMENDATION #2: EPA Should complete its
efforts with regard to RF electromagnetic fields (including
microwaves) and issue exposure guidelines independent of present
issues pertaining to lower frequencies. The current EPA report
inadvertently leads even the careful reader to conclude that the>
potential carcinogenicity of electric and magnetic fields of ELF
(i.e., power line) frequencies is the only—or at least the
principal—subject of concern with regard to nonionizing fielda.*
Such a conclusion would reinforce the skewed and somewhat ;
sensationalized picture presented to the public in recent years
by the news media and government agencies responding to this
publicity. The report should therefore declare explicitly that
the attention given to nonionizing electric and magnetic fields
derives in the first place from long-standing concern over'the
hazards of RF (including microwave) radiation. EPA has expended
substantial resources .on the study of such radiation over a
period dating back to the EPA's inception, and EPA should
complete its efforts directed toward the issuance of RF exposure
guidelines. MP fields present long-known and well-understood
hazards such as temperature elevation,in tissue and heat stress
resulting from acute exposuresagainst which users and the general
public must be warned and protected. Any published exposure
guideline should specifically identify the hazards from RF
exposure *
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APPENDIX A
M» tnff.
UNITED STATES ENVIRONMENTAL PROTECTION'
WASHINGTON. Q.C 20460
AGENCY
, ocr 12 m
OfftCC Of
SUBJECT: Science Advisory Board Review of the EPA
th* Carcinofenieity of Slectro«af^?i
FROM:
William a. Fmrlana,
Director
°5
of
TO:
of
Ken Sexton, Sc*0.
Director
Qffica of Health ,.
Office of Research
Director
Office of Radiation
office of Air mud Radiation (AHE-45i)
Kathleen Cortvmy, 0FO, Radiation Advisory
Science Mvisory Board (A-liUF)
review
doe«a«nt» ver* prepared *M reviewed
?a omc* off »«««axfeft 2
will b* availtisie to the SA1 in e*rl
* •?**»}•* *or »!•«•• to tfte public in
an external review draft. TUe Atfenev im
*1}0 °°— nt "«*•* »S » »!^««=
»viw.-An-Mrii.r drift IM* *lr«dy- l»«rv
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. , ir
relating to tha oia2li! w? ?S*
-
*' 5 ™^lltMpW;tl011 of * ujwn-and aniaal evidence
of oarcinogwueity rapport* by tha
inrozmation?
2 * '
f°r P°««*«in«r that thare is ian
hazard froB exposure to «xtr«B«ly low tz*m*ncy fiiiSs
lltad °
«£ * fi&Sif i.^itz «£x**nrrw T^T-r.|^%^^w1 tjt j^,,^ ^ 4m_..^ ^_ j ^%_ ^ . . .
th* way in which the
and
-»- MWM« St« ' °f
4. la
to?ic\in chapter S appropriate and is
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or which organization might do the research. We are-.'requesting
the SAB to address the following issues in theiir-feview' of the •*••
documents • "-'W^r?^',^*-..*:'
1} Does the document identify the major research needs for
EMF? specifically are any identified needs
inappropriate and are all the needs identified?
2) Is the level of detail sufficient to set priorities
among the research needs?
3) Do any research needs stand out as higher priority
issues for assessing human health risks?
"A~r"
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APPENDIX B: Detailed Technical Comments
Comments o£ the individual group members on Chapter 4 follow*
The described animal studies focus exclusively on RF
exposures and thus bear little relevance to ELF fields produced
by transmission lines and household electricity. The mechanisms
of tissue effects from 1000 Khz exposure may not relate to
mechanisms at 60 Hz. Therefore, as pointed out previously, RF
and ELF field effects should be handled separately in this
section of the report.
The specific presentation of experiments in this chapter
introduces problems. For example, reanalysis of the Guy et al.
data from 1985 to reach conclusions other than those presented by
the authors is inappropriate in this type of report. Sealing to
normalise absorption rate is questionable. Some RF studies may
be excessively thermal. The relevance of all studies should! be
discussed in regard to the spectrum of exposure frequencies.
The cited studies appear to have little relevance to ELF t
fields as produced by transmission lines and household *
electricity. For example, there is no evidence that the
interaction mechanisms involved at 1000 MHz are in any way
similar to those at 60 Hz. Since the interaction is most likely
to depend critically on frequency, scaling to normalize
absorption rate is certainly inappropriate. Moreover, the
grouping of glandular organs implied in the presentation is
highly unorthodox. No conclusions for ELF can be derived from
these experiments.
The microwave chapter should give the conclusion as
originally stated in the 1985 report by Guy et al., which
combined all malignant tumors and reported a significant
difference between exposed and controls, but this difference
disappeared when benign tumors were included. The Guy report
concludes that the observed differences are not of biological
significance,.
Kuch attention is given to the fact that the exposure
condition*via .the Guy study were "...calibrated to simulate human
exposure at; the. upper limit allowed by the ANSI standards" scaled
from the weight of a small child exposed to 450 MHz (a standard
radar). These calculations apparently do not take into account
that resonance for animals in the circularly polarized waveguide
used by Guy differs from estimates on resonance taken in an
anechoic chamber or a multimode cavity.
S-l
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The use of the post hoc analysis of the Guy data in this
document must be seriously questioned. Such an analysis should
at the very least be submitted for publication before it can add'
any benefit to the document. Such re-analysis of data is quite
common in literature. If Kuni believes in this re-analysis, he
should submit it for publication with all the appropriate
co-authors. If the study had been intended as a cancer study or
if it were ELF one might think that it was important enough to
the overall theme of the report to waive the peer review
requirement. Since the original Guy study meets neither of those
two criteria, there is no reason to include such a re-analysis in,
the present document*
The report states that the Sprague Dawley rat was chosen to
mimic heterafenaus variety of human population. But the Guy
study used all males and sprague Dawleys are an albino strain.
Creel has suggested many unusual attributes .of albinos. The
paper by Creel on albino rats as experimental 'animals should
therefore be cited and discussed.
If the Guy post hoc analysis is included in Chapter 4, it
should be given much less attention and the statistical . *
guestionability of the results should be focused. Four . :
significant differences can be found in the post hoc analysis of
the Guy data. The fact that the exposed group lived longer than
the control was not significant; nor was the analysis of the
cause of death, with regard to the tumor incidence, the post hoc
analysis showed significant differences using a one-tailed
Fisher's exact test for benign pheoehromocytoma of the adrenal
medulla (p < 0.023), malignant tumors at all sites (p < 0.0012),
carcinomas at all cites (p < 0.018), and glandular carcinoma for
combined glands (p < 0.018)* The EPA report makes no mention of
how many statistical tests were done on these data. It would
seem that multiple independent tests on all the possible effects
would have yielded a suspected significance that might even
exceed the four reported.
The Prausnitz and Susskind study was excessively thermal.
It is unclear how an exposure of o.l mW/c»2 over 4.5 minutes
could indue* a 3.3 degree C temperature increase, for example.
this study has been criticized and these other criticisms Should
be included in this report. The most important to include are
probably Roberts and Michaelson (Health Phvsics 44: 430-433.
1982) and Kirk (Life span and careinogenesis, in J. Elder and
EPA-60Q/8-83-Q26F, 1984). The criticisms focus on the fact that
the colony of mice had an infection of pneumonitis during the
study and that the leucosis reported may not have been leucosis.
The authors note that the exposed animals lived longer than the
controls (an observation also made by others) and suggest that
the mild heating enabled exposed animals to thwart the virus with
which the colony was infected. There is also a question of how
B-2
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many multiple comparisons were made to arriv** **• +-K
statistical significant effects reported h* Very fev
a robust study or conclusion.
B-3
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DISTRIBUTION LIST
Administrator
Assistant Administrators
Regional Aduinistrators
Director, Office of Health and Environmental Assessment
Director, Office of Health Research
Director, Office of Radiation Programs
Director, Health Effects Research Laboratory
Headquarters Librarian
Regional Librarians
National Technical Information Service
1-4
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