IEEE EMF HEALTH & SAFETY STANDARDS
Patrick A. Mason 1), Michael R. Murphy 1), and Ronald C. Petersen 2)
Air Force Research Laboratory Human Effectiveness Directorate 1)
Radio Frequency Radiation Branch Brooks Air Force Base, Texas, 78235
Independent Consultant Bedminster, New Jersey, 07921 2)
Tel: +1 210 536 2362, Fax: +1 210 536 3977, Email: patrick.mason@brooks.af.mil
?? ABSTRACT
With roots dating back to 1884, the Institute of
Electrical and Electronics Engineers (IEEE) is the
world’s largest technical professional society, with
more than 325,000 members, 1/3 from outside the
United States. The development of internationally
recognized voluntary standards, through an open
consensus process, has long been a major effort of
the IEEE. In 1966, IEEE co-sponsored the first US
radio frequency (RF) standard (C95.1-1966). In 1982,
C95.1-1982 was the first national standard in which
field limits were derived from the frequencydependent dosimetric quantity “specific absorption
rate” (SAR). Dosimetry and a threshold SAR of 4
W/kg are now the bases for most of the world’s RF
safety standards and guidelines, including those of
National Radiological Protection Board (NRPB),
International Commission on Non-Ionizing Radiation
Protection (ICNIRP), North Atlantic Treaty
Organization (NATO), and the United States
Department of Defense.
?? INTRODUCTION
The IEEE is one of the largest professional
organizations and is composed of a number of
professional societies (e.g., Engineering in Medicine
and Biology Society; Microwave Theory and
Techniques Society). Exposure standards pertaining
to subjects that are of interest to more than one
society (e.g., radio frequency safety standards) are
developed by Standards Coordinating Committees
(e.g., SCC-28, SCC-34) that are sponsored by the
IEEE Standards Board. The history of the American
National
Standard
Institute
(ANSI)/IEEE
RF/Microwave exposure standards is certainly
impressive. There are several recent reviews of the
ANSI/IEEE history and process [1-4]. In 1953, the
10-mW/cm2 exposure standard was recommended to
the United States Navy and this standard was based
on simple thermal models. In 1959, the United States
America Standards Institute (USASI) C95 project
was chartered and sponsored by the United States
Department of the Navy and IEEE. On November 9,
1966, the ANSI C95.1-1966 standard was approved
and was based on simple thermal models. This
standard covered 10 MHz to 100 GHz, the exposure
limit was 10 mW/cm2, and the 0.1-hour (6 minute)
averaging time was introduced. Remarkably, the
entire standard was only 1.2 pages in length and the
cover page is shown below:
In 1971, the ANSI C95.1-1971 standard was
approved and limits were established for E2 and H2.
In 1982, ANSI C95.1-1982 was approved and this
was the first national standard to incorporate
dosimetry, was frequency dependent, and based on
threshold SAR for behavioral disruption.
The
incorporation of limits based on SAR was critical
since the incident and internal electromagnetic fields
can be very different depending upon the size, shape,
and composition of the object. As we know today,
SAR is the common unit for comparing and
extrapolating laboratory results from bioeffects
studies.
In 1986, the National Council on Radiation
Protection and Measurements (NCRP) published
exposure recommendations that were SAR based, set
occupational exposure limits the same as ANSI
C95.1-1982, and set lower limits for the general
public. In 1988, the C95 committee became the
IEEE SCC-28. In 1991, the IEEE Standards Board
approved the C95.1-1991 standard. This standard
was two tiered, was based on SAR values, provided
relaxation of limits for partial-body exposures,
contained rules and definitions necessary for
implementation, and was developed after an
extensive evaluation of the scientific literature (see
Attachment 1). During the literature assessment,
classifications of findings were made without
prejudgement of the mechanisms of effects. The
intent was to protect exposed humans from harm by
any mechanism, including those from excessive
elevation of body temperature. The Biological
Validiation Working Groups were as follows:
Behavior, Biorhythms, Cardiovasculature, Central
Nervous System, Combined Effects, Development
and
Teratology,
Endocrinology,
Genetics,
Hematology-Immunology,
Metabolism
and
Thermoregulation,
Modulation,
Oncology,
Physiology, and Visual Systems. The finding of
these groups was that the most sensitive measures of
potentially harmful biological effects were based on
the disruption of food-motivated behavior in several
animal species under wide-ranging field parameters
(see Attachment 2).
The Maximum Permissible Exposure (MPE) values
are based on limiting the SAR to:
Whole-Body
Average
Spatial Peak*
Controlled/
Occupational
0.4 W/kg
Uncontrolled/
General Public
0.08 W/kg
8.0 W/kg
1.6 W/kg
* Per gram of tissue in the shape of a cube
Controlled environments are locations where there is
exposure that may be incurred by persons who are
aware of the potential for exposure as a concomitant
of employment, by other cognizant persons, or as the
incidental result of transient passage through areas
where analysis shows that the exposure levels may be
above the MPEs for the uncontrolled environment,
but do not exceed the MPEs for the controlled
environment.
Uncontrolled environments are locations where there
is exposure of individuals who have no knowledge or
control of their exposure. The exposures may occur
in living quarters or workplaces where there are no
expectations that the exposure levels exceed the
MPEs for the uncontrolled environment.
The exposure values (the values that are compared
with the appropriate MPEs) in terms of electric and
magnetic field strengths are the mean values obtained
by spatially averaging the squares of the fields over
an area equivalent to the vertical cross-section of the
human body. The spatial averaging can be obtained
by scanning (with a suitable measurement probe) a
planar area equivalent to the area occupied by a
standing adult human. An approximate method for
spatial averaging is to make measurements at equal
intervals (at least ten) along the axis of the projected
area of the exposed subject. The spatial average is
equal to the sum of the squares of the measured fields
divided by the number of measurements.
Above 15 GHz, the averaging time decreases with
increasing frequency from 6 and 30 minutes for the
controlled
and
uncontrolled
environments,
respectively, to 10 seconds at 300 GHz. The 10
second averaging time at 300 GHz (1 mm
wavelength) is consistent with the ANSI Z136.11993 (safe use of lasers) at 1 mm (where the two
standards meet). The averaging time was reduced in
the 1991 standard to preclude second degree (partial
thickness) skin burns associated with short exposures
at frequencies where the energy is absorbed in
superficial tissues.
For example, a 6-minute
averaging time and a 5-mW/cm2 MPE would allow
exposure to a peak power density of 3.6 W/cm2 for a
0.5 sec exposure (once every 6 minutes), which
would be above the threshold for skin burn from a
white light or infrared source.
Overall, the recommendations made in the IEEE
C95.1-1991 standard are designed to prevent harmful
effects in humans being exposed to electromagnetic
fields in the frequency range of 3 kHz to 300 GHz.
These exposure limits are biologically based and
reflect a consensus interpretation of relevant studies
from the bioelectromagnetics literature by qualified
scientists, physicians, and engineers. Adjustme nts to
the recommendations as a convenience to special
interest groups are not part of the process.
In 1997, the literature evaluation began for the next
revision of the exposure standard. This will be the
most comprehensive literature evaluation ever take
for a RF/microwave safety standard. Currently, there
are approximately 1400 citations in the database
(http://grouper.ieee.org/groups/scc28/).Peer-reviewed
and non-peer-reviewed publications, book chapters,
and reports are included in the database. Evaluations
are being completed by topic (engineering,
epidemiology, in vivo, in vitro, peripheral). Some of
the issues to be addressed in revising the standard
are: microwave/millimeter wave averaging time, the
need for two tiers, and spatial-peak SAR values and
averaging volume.
The IEEE SCC-28 is one of the several international
organizations that develop safety criteria for
RF/microwave
exposure.
For
standards
harmonization, it is important that members of these
international organizations interact with one another
to understand the rationale for exposure limits.
?? IEEE SCC PROCEDURES
IEEE Standards are developed through an open
consensus process (see Attachment 3). Approval of
an IEEE Standard (at the subcommittee level and at
the main committee level) requires a balance of
interests on committees, 75% return of ballots
(including abstentions), approval of 75% of returned
ballots (excluding abstentions), attempts to reconcile
all negative ballots, circulation of unreconciled
ballots to allow voters to reaffirm, comment, or
change their vote, and coordination with other
societies and organizations.
Currently in IEEE/ICES SCC-28, there are over 100
members from 13 countries. In recognition of the
growing international membership of SCC-28, IEEE
established the International Committee on
Electromagnetic Safety (ICES) in March 2001 as an
umbrella organization for SCC-28 and in the future
for SCC-34 and any other SCC involved in
developing standards for the safe use of
electromagnetic energy.
Members of the
IEEE/ICES SCC-28 Executive Committee are:
Chair: Dr. Eleanor Adair, Past Chair: Dr. John
Osepchuk, Executive Secretary: Ronald Petersen,
Treasurer: Arthur Varanelli, Membership: Dr. Tom
McManus, and International Liaison: Dr. Michael
Murphy.
The Executive Committee is responsible for policy,
procedures, broad direction, and administration, as
well as, adherence to process.
The five
subcommittees and Chairs are:
SC1: Techniques, Procedures, and Instrumentation;
Howard I Bassen (hib@cdrh.fda.gov)
SC2: Terminology, Units of Measurements, and
Hazard
Communication;
Richard
A.
Tell
(rtell@radhaz.co)
SC3:
Safety Levels with Respect to Human
Exposures, 0 – 3 kHz; Kent C. Jaffa
(kent.jaffa@pacificorp.com)
SC4: Safety levels with Respect to Human Exposures,
3 kHz – 300 GHz; Dr. C. K. Chou
(ck.chou@motorola.com) and Dr. John A. D’Andrea
(john.dandrea@navy.brooks.af.mil)
SC5: Safety Levels with Respect to ElectroExplosive
Devices;
John
DeFrank
(john.defrank@amedd.army.mil) and G. Drew Koban
(gkoban@relay.nswc.navy.mil)
?? HOW TO JOIN SCC28
IEEE/ICES is an International Consensus Standard
Setting Body. All are welcome to participate in the
meetings and deliberations of SCC28 and to vote and
participate fully on the Subcomittees. To apply for
voting membership on SCC28, please send an e-mail
or letter containing your resume to: Dr. Tom
McManus,
Membership
Committee
Chair,
IEEE/ICES SCC28, Department of Public Enterprise,
44
Kildare
Street,
Dublin
2,
Ireland
(tommcmanus@dpe.ie).
?? INFORMATION ON IEEE SCC34
SCC34 develops performance standards for
products using or producing electromagnetic energy.
For further information, contact the Chair: Ronald C.
Petersen (r.c.petersen@ieee.org).
?? REFERENCES
[1] J.C. Lin, “ANSI/IEEE Exposure Standards for
Radiofrequency Fields,” in Radiofrequency Radiation
Standards – Biological Effects, Dosimetry,
Epidemiology, and Public Health Policy, B. Jon
Klauenberg, M. Grandolfo, and D.N. Erwin, Eds.,
New York, Plenum Press, 1995, pp. 31-33.
[2] J.M. Osepchuk and R.C. Petersen. Safety
Standards for Exposure to RF Electromagnetic Fields,
IEEE Microwave Magazine, 2: 57-69, 2001
[3] R.C. Petersen, “New IEEE Standards on
Measurement
of
Potentially
Hazardous
Radiofrequency/Microwave Electromagnetic Fields,”
in Radiofrequency Radiation Standards – Biological
Effects, Dosimetry, Epidemiology, and Public Health
Policy, B. Jon Klauenberg, M. Grandolfo, and D.N.
Erwin, Eds., New York, Plenum Press, 1995, pp. 8999.
[4] R.C. Petersen, “Radiofrequency Safety StandardsSettings in the United States,” in Electricity and
Magnetism in Biology and Medicine, F. Bersani, Ed.,
London, Plenum Publishing, 1998, pp. 761-764.
Attachment 1
LITERATURE SURVEILLANCE
Engineering
Evaluation
In vivo and In vitro
Biological
Evaluation
Mechanism
s
Statistical
Validation
Evaluation of Exposure Risk Working Group
THRESHOLD SAR
Epidemiology
WHERE APPLICABLE
Attachment 2
Species and
Conditions
CW
225 MHz
Pulsed
1.3 GHz
CW
2.45 GHz
Pulsed
5.8 GHz
Norwegian Rat
Power Density:
SAR:
---------
10 mW/cm2
2.5 W/kg
28 mW/cm2
5.0 W/kg
20 mW/cm2
4.9 W/kg
Squirrel Monkey
Power Density:
SAR:
---------
---------
45 mW/cm2
4.5 W/kg
40 mW/cm2
7.2 W/kg
Rhesus Monkey
Power Density:
SAR:
8 mW/cm2
3.2 W/kg
57 mW/cm 2
4.5 W/kg
67 mW/cm2
4.7 W/kg
140 mW/cm2
8.4 W/kg
Attachment 3
IEEE SCC-28 Standard-Setting Process
IEEE
Standard
Subcommittee 4
• working groups
Main
Committe
e
IEEE
Standards
Board
American
National
Standard
American
National
Standards
Institute
Public
Comment