emf health & safety standards - who · radio frequency radiation branch human effectiveness...

Asian and Oceanian Regional EMF Scientific Meeting, 2001

Patrick Mason, PhD

Radio Frequency Radiation Branch

Human Effectiveness Directorate

Air Force Research Laboratory

Seoul, Korea23 October 2001

IEEE

EMF Health & Safety Standards


Institute of Electrical and Electronics Engineers (IEEE)

The IEEE is one of the largest professional societies in the world (325,000 members, 1/3 from outside of the U.S) and is composed of a number of professional societies (e.g., Engineering in Medicine and Biology Society) that sponsor standards committees

Standards pertaining to subjects that are of interest to more than one society (e.g., RF safety standards) are developed by Standards Coordinating Committees (e.g., SCC-28, SCC-34), that are sponsored by the IEEE Standards Board


History of ANSI/IEEERF/Microwave Exposure Standards

1953 10 mW/cm2 recommended to US Navy ?based on simple thermal model

1959 USASI C95 Committee/Project chartered?sponsored by U.S. Navy and IEEE

1966 American National Standards Institute (ANSI) C95.1-1966 approved?based on simple thermal models


C95.1 - 1966 (later ANSI/IEEE C95.1)

10 MHz - 100GHz

10 mW/cm2

0.1-hour (6 minute) averaging time introduced

1.2 pages long



1971 ANSI C95.1-1971 approved? 10 mW/cm2 - based on simple thermal models? limits for E2 and H2

1982 ANSI C95.1-1982 approved? incorporates dosimetry? frequency dependent? based on threshold specific absorption rate

(SAR) for behavioral disruption


Why is Specific Absorption Rate (SAR) important?

? The incident and internal electromagnetic fields can be very different, depending upon size and shape

? SAR is the common unit for comparing and extrapolating laboratory results (bioeffects studies)



1986 National Council on Radiation Protection and Measurements (NCRP) publishes recommendations:? SAR - based? occupational exposure limits the same

as ANSI C95.1-1982? lower limits for the general public

1988 ASC (ANSI) C95 Committee becomes IEEE SCC-28



1991 C95.1-1991 approved by IEEE Standards Board? SAR - based? two tier? induced current limits? relaxation for partial-body exposures? contains rules and definitions necessary

for implementation? based, in part, on literature evaluation


IEEE SCC-28 - Subcommittee 4Literature Evaluation Process

WHERE APPLICABLE

THRESHOLD SAR

LITERATURE SURVEILLANCE

In vivo and In vitroBiologicalEvaluation

EngineeringEvaluation

Mechanisms

StatisticalValidation

Evaluation of Exposure Risk Working Group

Epidemiology


Goals of Literature Assessment

During the literature assessment procedure, classifications of findings were made withoutprejudgement of mechanisms of effects

Intent was to protect exposed human beings from harm by any mechanism, including those arising from excessive elevations of body temperature


Biological Validation Working Groups

Behavior GeneticsBiorhythms ModulationCardiovasculature Hematology-ImmunologyEndocrinology Metabolism-ThermoregulationOncology Central Nervous SystemCombined Effects Development and TeratologyPhysiology Visual Systems


IEEE Standard for Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz,

IEEE C95.1-1991

FINDINGS:The most sensitive measures of potentially harmful biological effects were based on the disruption of food-motivated behavior in several animal species under widely-varying field parameters


Comparison of Power Density and SAR Thresholds of Behavioral Disruption

Species andConditions

CW225 MHz

Pulsed1.3 GHz

CW2.45 GHz

Pulsed5.8 GHz

Norwegian RatPower Density:SAR:

----------

10 mW/cm2

2.5 W/kg28 mW/cm2

5.0 W/kg20 mW/cm2

4.9 W/kg

Squirrel MonkeyPower Density:SAR:

----------

----------

45 mW/cm2

4.5 W/kg40 mW/cm2

7.2 W/kg

Rhesus MonkeyPower Density:SAR:

8 mW/cm2

3.2 W/kg57 mW/cm2

4.5 W/kg67 mW/cm2

4.7 W/kg140 mW/cm2

8.4 W/kg



IEEE C95.1-1991

The MPEs are based on limiting the SAR to:

Controlled/Occupational

Uncontrolled/General Public

Whole-Body-Averaged

0.4 W/kg 0.08 W/kg

Spatial Peak(per gram)*

8.0 W/kg 1.6 W/kg

*Per gram of tissue in the shape of a cube



IEEE C95.1-1991

Controlled Environments

Controlled environments are locations where there is exposure which 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 maximum permissible exposure (MPEs) for the uncontrolled environment but do not exceed the MPEs for the controlled environment.



IEEE C95.1-1991

Uncontrolled Environments

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 MPEsfor the uncontrolled environment.


IEEE C95.1-1991 - Spatial Averaging

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 (projected area)

Note: The spatial average 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


IEEE C95.1-1991: AVERAGING TIME (HIGH FREQUENCIES)

The averaging time decreases with increasing frequency (above 15 GHz) from 6 and 30 minutes for the controlled and uncontrolled environments, respectively, to 10 seconds at 300 GHz

Note: The 10 second averaging time at 300 GHz (1 mm wavelength) is consistent with ANSI Z136.1-1993 (for the safe use of lasers) at 1 mm (where the two standards meet). The averaging time was reduced in the 1991 standard to preclude 2nd degree 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 allows exposure to a peak power density of 3.6 W/cm2 for a 0.5 sec exposure (once every 6 minutes) which is above the threshold for skin burn from a white light or infrared source.



IEEE C95.1-1991

Summary of Standard

“Recommendations are made to prevent harmful effects in human beings 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. Adjustments to the recommendations as a convenience to special interest groups are not a part of the process


IEEE Standards Coordinating Committee 281997

Literature evaluation started for next revision

? ~ 1300 citations in database? non-peer reviewed papers, e.g., book

chapters and reports, are included? evaluations by topic

Some issues that will be addressed are:? microwave/millimeter wave averaging time? the need for two tiers? spatial-peak SAR values and averaging

volume


Revision of IEEE C95.1-1991:Literature Evaluation

The ~1300 citations currently in the literature database are organized as:

?engineering?epidemiology? in vitro? in vivo?peripheral


RF/Microwave Standards Activities

IEEE Standards Coordinating Committee 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 rationale for exposure limits


Importance of IEEE/ICES SCC-28 Activities(C95 Standards)

? forty year history of ANSI C95 standards?broadest scientific consensus? forms basis for numerous modern

standards?U.S. federal agencies mandated to adopt

voluntary standards?FDA models product performance

standards after ANSI standards, e.g., microwave ovens

?developed through open consensus process


Institute of Electrical and Electronics Engineers (IEEE) SCC-28 Procedures

Approval of an IEEE Standard Requires:*

?balance of interests on committees? 75% return of ballots (including abstentions)? approval of 75% of returned ballots (excluding

abstentions)? attempts made to reconcile all negative ballots? circulation of unreconciled ballots to allow voters

to reaffirm, comment or change their vote? coordination with other societies and

organizations

*Required at the subcommittee level and at the main committee level


Subcommittee 4• working groups

MainCommittee

IEEEStandard

IEEEStandards

Board

AmericanNationalStandard

AmericanNational

StandardsInstitute

PublicComment

IEEE SCC-28 Standard-Setting Process


IEEE/ICES SCC28 Executive Committee

Chair: Dr. Eleanor Adair

Past Chair: Dr. John Osepchuk

Executive Secreatary: Ronald Petersen

Treasurer: Arthur Varanelli

Membership: Dr. Tom McManus

International Liaison: Dr. Michael Murphy


SCC28 Main (Parent) Committee– Policy, procedures, broad direction, and administration– Adherence to Process

5 subcommittees (SC)– SC1: Techniques, Procedures, & Instrumentation– SC2: Terminology, Units of Measurement, and Hazard

Communication– SC3: Safety Levels with Respect to Human Exposure,

0-3 kHz– SC4: Safety Levels with Respect to Human Exposure,

3 kHz – 300 GHz– SC5: Safety Levels with Respect to Electro-Explosive

Devices

IEEE/ICES SCC-28Over 100 Members from 13 countries


Membership Affiliations for SCC-28/SC-4(SC-4: 3 kHz – 300 GHz)

Research:university 37 (30%)nonprofit 8

(6%)military 15 (12%)non-military government 30 (24%)

Industry 12 (10%) Industry - Consulting 4 (3%)Government - Administration 5 (4%)General Public & 14 (11%)

Independent Consultants


Membership Principle Disciplines for SCC-28/SC-4

Physical Sciences 41 (33%)Life Sciences 54 (43%)Medicine 12 (10%) Radiology, Pharmacology, 4 (3%)

ToxicologyOthers (Law, Medical History, 14 (11%)

Safety, etc.)


2001 IEEE SCC-28 becomes IEEE/ICES SCC-28

(International Committee on Electromagnetic Safety)



Invitation to Participate

• IEEE/ICES is an International ConsensusStandard Setting Body

•We welcome your participation

•To learn more about IEEE/ICES:• (http://grouper.IEEE.org/groups/scc28)•e-mail Tom McManus ([email protected])

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