Federal Radiation Protection Guidance for Exposure of the General Public; Notice ENVIRONMENTAL PROTECTION AGENCY

SUMMARY: The Agency is proposing to make recommendations to the

President for new guidance to Federal agencies on radiation protection

which would have two effects: it would cause a five-fold reduction in

the maximum allowable risk of cancer from any Federally regulated

activity involving nuclear materials or other sources of radiation; and

it would decrease the cost of Federal regulation of radiation by

promoting uniform treatment of radiation by all Federal agencies, and

reducing costly duplicative and conflicting requirements.

The new guidance would replace those portions of previous

recommendations that apply to protection of the general public,

approved by Presidents Eisenhower and Kennedy in 1960 and 1961,

respectively. New Federal guidance issued in 1987 replaced those

portions of the 1960 and 1961 guidance that applied to protection of

workers.

These proposed recommendations are based on a review of existing

guidance in light of current scientific understanding of the risks of

exposure to ionizing radiation and of the experience of Federal

agencies in its control. They include both qualitative guidance on

radiation protection and numerical guides for limiting radiation doses

to the general public. The most significant proposed changes are that:

the Radiation Protection Guide (RPG) be expressed in terms of a single

weighted sum of doses to organs, and the separate RPGs for individual

organs deleted; the current RPGs limiting the average genetic dose to

members of the U.S. population to 5 rems in 30 years and the annual

whole body dose to 500 millirem dose equivalent be replaced by a single

RPG of 1 millisievert (100 millirem) effective dose equivalent received

by or committed in a single year to any individual from all sources

combined; doses from individual sources normally be limited to a

fraction of the RPG; and increased emphasis be given to the principle

that all exposure should be maintained as low as reasonably achievable,

within the RPG.

The Agency invites written comments on these proposals and shall

also hold a public hearing, as discussed below. All written and oral

comments will be considered carefully in preparing our final

recommendations to the President.

DATES: Written comments in response to this notice of proposed guidance

must be received on or before February 21, 1995, to be ensured full

consideration. A public hearing will be held in Washington, D.C., on

February 22 and 23, 1995. Requests to participate should be received on

or before January 23, 1995. The schedule, location, and procedures for

this hearing will be published in the Federal Register shortly.

ADDRESSES: Written comments (in duplicate if possible) should be

submitted to: Central Docket Section Section (6102), Attn.: Docket No.

A-83-41, U.S. Environmental Protection Agency, Washington, DC 20460.

Written comments, the public hearing record, and other documents

related to this rulemaking will be filed under the above docket number

in Room M1500 at Waterside Mall, U.S. Environmental Protection Agency,

401 M Street, S.W., Washington, DC. The docket may be inspected between

8:00 a.m. and 4:00 p.m. on weekdays. A reasonable fee may be charged

for copying.

Requests to participate in the public hearing should be submitted

to Allan C. B. Richardson, Deputy Director for Federal Guidance,

Criteria and Standards Division, Office of Radiation and Indoor Air

(6602J), U.S. Environmental Protection Agency, Washington, D.C. 20460.

Requests to participate in the public hearing should include an outline

of the topics to be addressed, the amount of time requested, and the

names of the participants. EPA may allow testimony to be given at the

hearing without prior notice, subject to time constraints at the

discretion of the hearing officer.

FOR FURTHER INFORMATION CONTACT: Allan Richardson at the above address

(telephone (202) 233-9213; FAX (202) 233-9629) concerning these

proposed recommendations or the public hearing.

SUPPLEMENTARY INFORMATION:

Introduction

The Administrator of the Environmental Protection Agency (EPA) has

the responsibility to ``...advise the President with respect to

radiation matters, directly or indirectly affecting health, including

guidance for all Federal agencies in the formulation of radiation

standards and in the establishment and execution of programs of

cooperation with States.'' This authority stems from Executive Order

10831; the Atomic Energy Act of 1954, as amended; and Reorganization

Plan No. 3 of 1970. Guidance to Federal agencies has historically

consisted of both qualitative and quantitative recommendations

expressed as ``Federal Radiation Protection Guidance.'' The guidance

proposed here would replace those portions of existing Federal

Radiation Protection Guidance, adopted in 1960 (25 FR 4402) and 1961

(26 FR 9057), that apply to protection of the general public.

The purpose of Federal guidance is to provide a common framework to

help ensure that the regulation of exposure to ionizing radiation is

carried out by Federal agencies in a consistent and adequately

protective manner. Although the individual Federal agencies have

determined, and will continue to determine, the details of specific

regulations, it is intended that they adhere to these proposed

recommendations as basic, minimum requirements. It should be

recognized, however, that in some situations application of these

recommendations may be superseded by specific statutory requirements.

These proposed recommendations have been developed by EPA in

cooperation with the Departments of Agriculture, Commerce, Defense,

Energy, Health and Human Services, Housing and Urban Development,

Interior, Justice, Labor, and Transportation; the National Aeronautics

and Space Administration; and the Nuclear Regulatory Commission. In

addition, the Conference of Radiation Control Program Directors of the

States contributed to the development of this proposal. This

cooperation was carried out through an extensive series of interagency

meetings carried out between 1986 and 1992, and agency reviews

conducted in 1993.

Previous Relevant Actions by the FRC and EPA

On May 13, 1960, President Eisenhower approved the first

recommendations of the former Federal Radiation Council (FRC) for

guidance to Federal agencies on the protection of workers and the

general public from radiation (25 FR 4402). This guidance was extended

by further recommendations approved by President Kennedy on September

26, 1961 (25 FR 9057).

Following a lengthy review by Federal agencies of those portions of

the 1960 and 1961 guidance that applied to occupational exposure the

Administrator of EPA made new recommendations for protection of workers

which were approved by President Reagan on January 27, 1987 (52 FR

2822). Those recommendations motivated a number of the changes now

proposed here for protection of the general public.

During the period since the current guidance was issued, EPA, alone

and in concert with other Federal agencies, has sponsored major reviews

of the health risks from exposure to low level ionizing radiation by

the Committee on the Biological Effects of Ionizing Radiation (BEIR),

National Academy of Sciences--National Research Council. These reviews,

which were published in 1972, 1980, 1988, and 1990, each incorporated

new scientific information that had become available since the

preceding review and contributed directly to the deliberations which

have resulted in these proposed recommendations.

Scope of the Proposed Guidance

These recommendations would apply to most exposure of the general

public to sources of ionizing radiation that are created or influenced

by human activities, the principal exceptions being exposure of

workers, of patients for medical purposes in the practice of the

healing arts, and of the general public from accidents. They would

apply, for example, to exposure of members of the general public due

to: (a) emissions of radioactive materials or radiation from

industrial, defense-related, and scientific operations; (b) use of

radiation and radionuclides in consumer products and medicine (except

for beneficial exposure of patients); (c) mining and processing of ores

that contain naturally-occurring radioactive materials; (d) disposal of

wastes generated by any of the above operations; and (e) transportation

of radioactive materials involved in any of the above operations.

Specific examples include, but are not limited to: nuclear

installations, including mines, mills, and processors of uranium and

thorium, nuclear fuel fabrication plants, nuclear reactors (nuclear

power plants, critical and subcritical facilities, and research

reactors), spent fuel storage and processing facilities, and weapons

production, testing, and storage facilities; x-ray generators and

radioactive sources; irradiation installations, such as particle

accelerators and large irradiators for teletherapy, radiosterilization,

and commercial product irradiation; inspection devices in airports;

consumer products such as static electricity elimination devices, ion

generating tubes, smoke detectors, and devices for producing light or

an ionized atmosphere, such as for dials and laboratory measurements;

and radioactive waste installations where radioactive wastes are

handled, treated and conditioned, temporarily stored, or permanently

disposed of.

These proposed recommendations also address most terrestrial

sources of exposure arising from human activities (these principally

involve naturally-occurring radioactive materials), but not exposure

due solely to background radiation or due to globally-dispersed effects

of past activities and accidents. Excluded, for example, is

consideration of variations in exposure which result from geographic

location, as well as the small annual dose increment from past weapons

tests and residual global contributions of past nuclear accidents, like

that at Chernobyl in 1986, because it is not practicable to contemplate

their control. For the purpose of these recommendations, ``background

radiation'' includes radiation of cosmic and solar origin at the

surface of the earth and radiation from naturally-occurring primordial

and cosmogonic radionuclides found in the earth's crust or produced in

the upper atmosphere by cosmic or solar radiation (including

radioactivity normally ingested in food and water) that is not enhanced

by human activities.

By technological means, however, exposure to naturally-occurring

radionuclides that might otherwise be considered sources of ``natural

background'' may be enhanced. Technologically-enhanced exposure to

natural radiation may be defined as exposure to natural sources of

radiation which is increased by (or would not occur without) a human

activity. Examples of such sources include radon and its progeny

accumulated in buildings; wastes from mineral ores, including ores

which are mined for uses or purposes other than for their radioactive

isotopes; wastes and/or emissions from the burning of coal, oil, and

natural gas; ion exchange resins and sludge from drinking water

treatment; scale in oil- and gas-field piping; articles made from

naturally-occurring radioactive materials, such as thorium in lantern

mantles and in certain optical glasses, and uranium in certain ceramic

glazes; and cosmic rays experienced during high altitude airplane

flights.

To the extent that exposure to such sources is controllable, they

are addressed by these recommendations. However, the guidance does not

recommend that all situations that could lead to increased exposure

should necessarily be regulated. For example, there is no readily

applicable means to reduce the small increase in radiation exposure

while in flight. In addition, it would require many circumnavigations

of the globe by airline on non-business matters to approach the

recommended limit for dose to individuals. Similarly, we believe it is

also not appropriate to regulate, for example, exploration of caves,

mountain climbing, or residence in high altitude locations because of

technologically-enhanced radiation. Decisions on what exposures are

appropriate candidates for reduction through regulation have been and

will continue to be based on legislative mandates and decisions by

regulatory agencies.

The largest single source of exposure of the general public is

radon. Radon, a naturally-occurring radioactive gas, can accumulate in

any structure that limits the free exchange of indoor and outdoor air.

There are two general categories of sources that can generate

significant amounts of radon within a building: radium-bearing soil or

rocks naturally situated beneath or near the building and radium-

bearing materials used in construction or as fill beneath or near the

building. Although exposure to radon from sources of the first kind may

be enhanced or reduced by building location, design, or construction,

these factors usually are not subject to direct Federal or State

control. Exposure to the second category of sources (radium-bearing

materials placed in or near a building) may be subject to direct

regulatory control or alleviation through Federal or State programs.

The numerical limits for individual dose proposed in this guidance

do not include the contribution from indoor radon produced by either of

the above categories of sources. EPA and the Centers for Disease

Control have provided separate advice to the public for protection

against exposure to indoor radon in A Citizen's Guide To Radon (EPA

document 402-K92-001, May 1992, and subsequent editions) and EPA has

published a series of other technical publications, pursuant to Pub. L.

100-551 (Oct. 28, 1988, 102 Stat. 2755, amending the Toxic Substances

Control Act, 15 U.S.C. Secs. 2601-2692). That advice is consistent with

this proposed guidance, where applicable.

Finally, these recommendations apply only to the management of

normal operations of facilities and devices that may expose members of

the public to radiation: that is, to controllable exposure to radiation

and releases of radionuclides that may expose the general public.

Normal operations include both those conditions that are expected to

occur with certainty as well as those that may be predicted to occur

with a reasonably large probability (e.g. anticipated operational

occurrences at nuclear reactors), but not conditions with a very low

probability of occurrence, such as the unintended re-entry of a

satellite containing radioactive materials. These recommendations also

do not apply to nuclear incidents, such as a major accident at a

nuclear facility or the result of terrorist activity, or to exposure

resulting from acts of war. Guidance for establishing radiological

emergency response plans and for making radiation protection decisions

during nuclear incidents has been provided by EPA in the Manual of

Protective Action Guides and Protective Actions for Nuclear Incidents

(EPA-520/1-75-001-A), pursuant to regulations issued by the Federal

Emergency Management Agency (47 FR 10758, March 11, 1982). Additional

guidance has been provided by the Food and Drug Administration on the

prophylactic use of potassium iodide during radiological emergencies

(47 FR 28158, June 29, 1982) and on the use of food and animal feed

contaminated by an incident (47 FR 47073, October 22, 1982, and,

jointly with the Department of Agriculture, 51 FR 23155, June 25,

1986).

Exposure to radiation as a medical patient, which may occur for

diagnostic or for therapeutic purposes, is not covered by these

recommendations. Recommendations of the Administrator of EPA and the

Assistant Secretary for Health of the former Department of Health,

Education, and Welfare concerning diagnostic use of radiation, approved

by President Carter in 1978, are provided in Radiation Protection

Guidance to Federal Agencies for Diagnostic X Rays (43 FR 4377).

Additional specific recommendations and guidance on patient selection,

evaluation of radiation exposure, quality assurance, and related topics

have been published by the Department of Health and Human Services.

However, decisions on the diagnostic or therapeutic use of radiation

are the responsibility of individual patients and their physicians, and

such decisions should be based on the benefits and risks of the use of

radiation for the conditions specific to each patient. Since those

decisions will involve considerations quite different from those

addressed here--exposure of the general public to a variety of sources

of general societal benefit--these recommendations do not apply to

exposure of patients.

These recommendations also do not apply to occupational exposure.

Federal agencies should normally regulate or manage the exposure of

workers in accordance with Radiation Protection Guidance to Federal

Agencies for Occupational Exposure (52 FR 2822), approved by President

Reagan in 1987.\1\ However, when workers can be exposed under

conditions that also apply to members of the public (e.g., when the

public has unlimited access to the work site), the source of such

exposure should be controlled in conformance with these proposed

recommendations for protection of the general public.

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\1\In some situations the distinction between members of the

public and workers will have to be carefully considered. A ;useful

test for determining whether individuals should be considered

workers or members of the public is whether or not their presence in

the exposure situation in question is within the scope of their

employment.

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The Need for Revision of the 1960 Guidance

Since the current guidance was issued in 1960, knowledge of the

effects of ionizing radiation on humans has increased substantially.

The BEIR Committee of the National Academy of Sciences--National

Research Council conducted major reviews of the scientific data on

health risks of low levels of ionizing radiation in 1972 and again in

1980.\2\ Portions of the information presented in the latter report

were expanded in a 1988 publication on risks from exposure to alpha

radiation.\3\ A comprehensive, major new review was completed in

1990.\4\ Similar reviews have been published by the United Nations

Scientific Committee on the Effects of Atomic Radiation in 1977, 1982,

1986, and 1988.\5\ The most important results from these reviews,

carried out over a period of more than two decades, are that, although

estimates of the nature and general magnitude of the risks from

radiation have not undergone fundamental revision, estimates of the

principal risk, that of cancer, have increased roughly threefold and

have become more certain.

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\2\The Effects on Populations of Exposure to Low Levels of

Ionizing Radiation, National Academy of Sciences, Washington, D.C.,

1972; The Effects on Populations of Exposure to Low Levels of

Ionizing Radiation; 1980, National Academy Press, Washington, D.C.,

1980.

\3\The Health Risks of Radon and Other Internally Deposited

Alpha-Emitters, National Academy Press, Washington, D.C., 1988.

\4\Health Effects of Exposure to Low Levels of Ionizing

Radiation, National Academy Press, Washington, D.C., 1990.

\5\Sources and Effects of Ionizing Radiation, United Nations,

New York, 1977; Ionizing Radiation: Sources and Biological Effects,

United Nations, New York, 1982; Genetic and Somatic Effects of

Ionizing Radiation, United Nations, New York, 1986; Sources,

Effects, and Risks of Ionizing Radiation, United Nations, New York,

1988.

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While our knowledge of the effects of radiation has become more

definitive, the extent of our use of radiation has increased and our

policies for regulating it have evolved. Prior to 1960, major uses of

radiation were limited, and the primary concern of radiation protection

was to ensure that doses to those few individuals that were affected

did not exceed limits on dose from all sources combined. Since then,

the numbers and types of man-made radiation sources have greatly

increased, and, at the same time, public concern about environmental

contaminants of all kinds has become an important influence in their

management. Of particular significance is that the focus of the many

environmental policies and laws that have emerged during the past two

decades has been more on improving the levels of control of individual

sources of contamination than on establishing a single acceptable level

of risk to individuals from all sources combined. This shift of concern

has led to the development of new concepts for determining the

appropriate level of control of specific kinds of sources. For

radiation sources, it has meant that attention has been focused on

assessing the potential impact of each source, or class of similar

sources, on populations and on the capabilities and costs of controls

to reduce that impact. The result has been the promulgation of a series

of regulatory requirements that are based on the specific

characteristics of particular classes of sources of public exposure to

radiation. These requirements invariably have been more restrictive

than those required to meet the existing Federal guidance on dose to

individuals from all sources combined.

Concurrent with the improved understanding of the effects of

ionizing radiation and the evolution of its regulation, international

and national advisory groups have refined and revised their basic

recommendations on radiation protection. In 1977, the International

Commission on Radiological Protection (ICRP) published revised

recommendations\6\ that have since been adopted, in whole or

substantial part, in most developed countries. In 1990, the ICRP issued

revised general recommendations\7\ that, for control of exposure of the

general public, expanded on those issued in 1977, notably in the areas

of policy for control of individual sources and the methodology for

expressing doses and risks from radiation. National bodies have also

contributed to the evolution of radiation protection practice. In the

U.S., the most recent (1993) recommendations of the National Council on

Radiation Protection and Measurements (NCRP)\8\ are, in most cases,

consistent with those of the ICRP. The changes in the recommendations

of these organizations reflect the improved understanding of effects on

health of ionizing radiation, new methodologies for evaluating doses

and risks from ionizing radiation, developing public policy on

acceptable levels of risk, and refinements in the application of basic

radiation protection principles to the regulation of individual sources

of exposure of members of the public.

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\6\Recommendations of the International Commission on

Radiological Protection, ICRP Publication 26, Pergamon Press,

Oxford, 1977.

\7\1990 Recommendations of the International Commission on

Radiological Protection, ICRP Publication 60, Pergamon Press,

Oxford, 1991.

\8\Limitation of Exposure to Ionizing Radiation, NCRP Report No.

116, National Council on Radiation Protection and Measurements,

Bethesda, MD, 1993.

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All of the above developments--improved estimates of radiation

risk, experience in regulating the constantly expanding complex of

applications of ionizing radiation, and the evolution of improved basic

concepts and methodology for radiation protection--have contributed to

the need for this proposed revision of the 1960 guidance.

Effects of Radiation on Human Health

Effects on human health of concern from exposure to low levels of

ionizing radiation may be divided into three categories.\9\ The first

of these encompasses all forms of cancer (including leukemias). Cancers

associated with radiation are not distinguishable from those associated

with other causes. Although radiogenic cancers are observed in humans

over a range of higher doses,\10\ it is necessary to infer the risk of

cancer at the exposure levels normally encountered by members of the

public because there is insufficient information to draw direct

conclusions based on observations of cancer at these levels.

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\9\A fourth category of effects, designated ``non-stochastic,''

occurs at dose levels higher than those addressed by these

recommendations. They are of importance for managing the response to

nuclear accidents (see EPA-520/1-75-001-A, op. cit.).

\10\We use the general term ``dose'' to mean the dose

equivalent, effective dose equivalent, committed dose equivalent, or

committed effective dose equivalent, with the precise meaning to be

inferred from the text. When precision is important, we use the full

term. In 1990 the International Commission on Radiological

Protection adopted new terminology (and definitions) for these

quantities: equivalent dose in place of dose equivalent, and

effective dose in place of effective dose equivalent. Although these

terms are simpler and are acceptable for use, we use the older, more

explicit terms.

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The second category encompasses hereditary effects (mutations)

induced in the reproductive cells of exposed individuals and

transmitted to their descendants. The severity of hereditary effects

ranges from inconsequential to debilitating or fatal. Although such

effects are observed in studies of animals at high doses, excess

hereditary effects have not yet been confirmed in epidemiological

studies of the descendants of exposed human populations.

Both cancer and hereditary effects are postulated to be caused by

``stochastic'' (i.e. random) direct or indirect interactions of

ionizing radiation with the genetic materials in living cells. In view

of the extensive, albeit incomplete, scientific evidence supporting

this view, including much theoretical and experimental radiobiology, it

is commonly assumed that at low levels of exposure the probability of

incurring either cancer or most serious hereditary effects increases

linearly with dose, without a threshold. The severity of such effects

is not believed to be related to the amount of dose received. That is,

it is the probability of occurrence of a cancer or an hereditary

effect, not its severity once it has been induced, that is assumed to

be dependent upon the size of the dose.

The risks to health from exposure to low levels of ionizing

radiation have been reviewed by the National Academy of Sciences, as

noted earlier, in a series of reports published between 1972 and 1990.

Regarding cancer, there continues to be divided opinion on how to

interpolate between the absence of radiogenic cancers at zero dose and

the observed effects of radiation (mostly at higher doses than those

normally encountered) to estimate the most probable effects of the

doses actually encountered by members of the public.\11\ A

preponderance of scientists believe that the available data best

support the use of a linear model for estimating the effect of such

doses. Some scientists, however, believe that other models provide

better estimates. These differences of opinion have not been totally

resolved by studies of the effects of radiation in humans, the most

important of which are those of the Hiroshima and Nagasaki atom bomb

survivors. Over the last decade an extensive reevaluation of the doses

and effects in these survivors has been carried out. With respect to

cancer, this reevaluation has strengthened the evidence for use of the

linear model at doses near background levels.

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\11\The risk of interest is not that at or near zero dose, but

that due to small increments of dose above the pre-existing

background level. Background in the U.S. is typically about 3 mSv

(300 mrem) effective dose equivalent in a year, or 0.2 Sv (20 rem)

in a lifetime. Approximately two thirds of this dose is due to

radon, and the balance comes from cosmic, terrestrial, and internal

sources of exposure.

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These studies have also resulted in increased estimates (roughly

threefold between 1972 and 1990) of the most probable risk of cancer

from environmental levels of radiation. Nonetheless, the estimated

number of health effects induced by incremental doses of radiation

comparable to natural background levels remains small enough, relative

to the number that already occur from other causes, that in all

likelihood it will never be possible to detect them in human

epidemiological studies. This lack of detectability does not mean,

however, that such effects on health do not occur. In the absence of

reliable evidence to the contrary, the Agency believes that it is

appropriate, for radiation protection purposes, to assume that at and

just above the level of natural background the risk of cancer and most

serious hereditary effects increases linearly with increasing dose,

without a threshold. That is, we assume that any increase in exposure

to ionizing radiation carries the potential for causing harm to health.

This assumption has been employed in the development of this guidance,

and is consistent with current as well as historical practice for

radiation protection world-wide.

The third category of health effects involves those exposed in

utero. It has long been believed that the unborn are more sensitive

than are adults to the induction of cancer by radiation. The unborn are

also subject to various radiation-induced physical malformations.\12\

Recent studies, however, have drawn renewed attention to the apparently

greater risk of severe mental retardation from exposure of the unborn.

These studies indicate that the sensitivity of the fetus is greatest

during the period from 8 weeks to 15 weeks after conception, and

continues at a lower level during the period 16 to 25 weeks.\4\ The

risk of less severe mental retardation--manifested as a lowered

Intelligence Quotient--is similarly elevated during these periods.

Although it is not clear to what extent the occurrence and degree of

retardation are proportional to the dose (or whether there is a

threshold dose for these effects), it is prudent to assume, for

regulatory purposes, that there is a linear, non-threshold relationship

between these effects and the dose delivered to the fetus during these

periods.

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\12\These include small head circumference (microcephaly), brain

size (microencephaly), eye malformations, and intrauterine growth

retardation.

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For radiation protection purposes EPA assumes, using a linear, non-

threshold model, an estimated risk to an average member of the U.S.

population of 5 x 10-2 fatal cancers per sievert\13\

(5 x 10-4 fatal cancers per rem) delivered at low dose rates.\14\

(That is, we estimate that if 100,000 people chosen at random from the

U.S. population were each given a uniform dose of 1 mSv (0.1 rem) to

the entire body at a low rate of exposure, five cases of fatal cancer,

on average, would occur during their remaining lifetimes, in addition

to the roughly 20,000 cases that normally would occur from other

causes.) The risk of inducing severe hereditary effects in their

offspring is estimated to be smaller than that for cancer, namely, on

the order of 10-2 per sievert (10-4 effects per rem).\15\ The

risk of severe mental retardation from doses to a fetus is estimated to

be greater per unit dose than the risk of cancer in the general

population--5 x 10-1 per sievert (5 x 10-3 per rem)\16\--but

the period of susceptibility is very much shorter.

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\13\The traditional special unit for dose equivalent has been

the rem. The special unit sievert (Sv) in the International System

of Units, adopted in 1979 by the General Conference on Weights and

Measures, is now in general use throughout the world. The RPGs

recommended here may be expressed in either of these units. One

sievert is equal to 100 rem. The prefix ``milli'' (m) means one

thousandth.

\14\``Low dose rates'' here means dose rates on the order of or

less than those from background radiation (see footnote 11). This

value for the risk from such doses incorporates a dose rate

effectiveness factor of two.

\15\The risk of severe hereditary effects in the first two

generations, for exposure of the reproductive part of the

population, is estimated to be 5 x 10-3 per Sv (5 x 10-5

per rem). For all generations the risk is estimated to be

1.2 x 10-2 per Sv (1.2 x 10-4 per rem). For exposure of

the entire population, which includes individuals past the age of

normal child-bearing, each estimate is reduced to 40% of the cited

value.

\16\The risk for mental retardation during the 8th through 15th

week [estimated to be 4 x 10-1 per Sv (4 x 10-3 per rem)]

plus the risk during the 16th through 25th week [estimated to be

10-1 per Sv (10-3 per rem)].

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The National Academy of Sciences has judged the 90% confidence

limits for their most recent estimates of the risk of cancer to be

about a factor of three greater and a factor of two less than their

estimate of the most probable value. They also observe that, at the low

doses and dose rates of concern in this guidance, the possibility that

there may be no risk cannot be ruled out, since epidemiological data

cannot rigorously exclude the existence of a threshold. The numerical

values of risks of genetic abnormalities and mental retardation are

somewhat less well established. In spite of uncertainties in the data

and its analysis, however, estimates of the risks from exposure to low

levels of ionizing radiation are better characterized than those for

virtually any other environmental carcinogen.

Basic Principles

In recommending the 1960 Federal guidance, the Federal Radiation

Council said: ``Fundamentally, setting basic radiation protection

standards involves passing judgment on the extent of the possible

health hazard society is willing to accept in order to realize the

known benefits of radiation'' (25 FR 4402). The need to make this

judgment led to three basic principles that have governed radiation

protection for many decades in the United States and in most other

countries. Although the precise formulation of these principles has

evolved over the years, their intent has remained essentially

unchanged.

The first principle is that any activity involving the exposure of

people to ionizing radiation should be sufficiently beneficial to

society to warrant the exposure; i.e., a finding should be made that an

activity causing exposure is ``justified.''

The second is that, for justified activities, exposure of people

should be ``as low as reasonably achievable.'' This principle commonly

has been designated by the acronym ``ALARA'' in the United States, and

is called ``optimization'' of radiation protection in international

practice.

The third is that, even for justified and optimized exposures, the

maximum dose to any individual should be limited so as not to exceed an

acceptable level of risk. This is referred to as ``limitation.''

The objective of the first two principles is to minimize

(consistent with benefits and costs) the estimated total harm (i.e.

health detriment) in the entire population from each source of

exposure; they do not, however, limit the way that harm is distributed

among individuals. They are, in this sense, ``source-related''

radiation protection requirements. The purpose of the third principle,

that of limitation of the maximum allowed dose, is to provide an upper

bound on risk to individuals. This principle, which is an ``individual-

related'' requirement, may be carried out in two ways: first, through

limitation of the potential dose from all sources of exposure combined,

and second, through additional more specific limitations on the doses

from individual sources.

The following seven proposed recommendations directly express,

expand upon, and implement these three basic principles in light of

current improved knowledge of the risks of radiation and of the variety

and extent of uses of radiation. In particular, they reflect lower

upper limits on dose to individuals from all sources combined, they

make explicit the need for further limitation of doses from individual

(or classes of) sources of exposure that is more restrictive than that

for all sources combined, and they introduce improved methods for

assuring that all of the various components of risk associated with

radiation exposure are accounted for in radiation protection

requirements for limiting exposure of the public.

Recommendation 1

There should be no exposure of the general public to ionizing

radiation unless it is justified by the expectation of an overall

benefit from the activity causing the exposure. Justified activities

may be allowed, provided exposure of the general public is limited

in accordance with these recommendations.

The principle that activities causing exposure of the general

public should produce a net societal benefit has long formed a

cornerstone of radiation protection policy, even though the judgment of

net benefit is not easily made. The 1960 Federal guidance states:

``There should not be any man-made radiation exposure without the

expectation of benefit resulting from such exposure* * *,'' and ``It is

basic that exposure to radiation should result from a real

determination of its necessity.''

Other advisory bodies have used language which has essentially the

same meaning. In its 1990 revision of international guidance, the ICRP

said ``* * *no practice* * *should be adopted unless it produces

sufficient benefit to the exposed individuals or society to offset the

radiation detriment it causes.'' When it addressed this issue in 1975,

the NCRP said, ``* * *all exposures should be kept to a practicable

minimum; * * *this principle involves value judgments based upon

perception of compensatory benefits commensurate with risks, preferably

in the form of realistic numerical estimates of both benefits and risks

from activities involving radiation and alternative means to the same

benefits.''\17\

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\17\Review of the Current State of Radiation Protection

Philosophy, NCRP Report No. 43, National Council on Radiation

Protection and Measurements, Bethesda, MD, 1975.

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These recommendations would continue the requirement for

justification in terms of an overall benefit. An obvious problem in

making this judgment is the difficulty of assessing, in comparable

terms, costs (including risks) and benefits. Given this situation,

informed value judgments may be necessary, and, in fact, are usually

all that is possible.

The determination that a particular activity involving exposure of

the general public is justified is often a complex process. Commonly,

it is not made by those directly responsible for radiation protection

decisions. For a few activities, like the x-ray examination of feet for

shoe-fitting practiced many years ago, agreement that there is not a

net benefit was easy to achieve. The decision was simplified in that

example because the risks and benefits accrued to the same individuals.

This is usually not the case. In extreme cases the determination can be

far more complex. For a major industrial application of radiation, for

example, the determination may involve not only the benefits and the

costs (direct, health, and environmental) of construction, operation,

waste disposal, accidents, and eventual decommissioning, but also the

tradeoffs between the activity and the economic, societal,

environmental, and resource implications of alternative means to

achieve the same result.

In any case, for a major activity the analysis should make a

reasonable demonstration that the benefit associated with the proposed

activity clearly outweighs the risks associated with the use of

ionizing radiation, including those associated with normal operations,

reasonably possible incorrect operation or management, and disposal of

wastes over the life cycle of the activity. When the consequences can

be significant, the analysis should include low probability events and

exposure pathways.

The process of balancing these factors may eventually involve

congressional, executive, and judicial inputs. One vehicle for

assisting such decision-making is the National Environmental Policy Act

of 1969 which, in effect, requires Federal agencies to assess and

consider the above factors for any major Federal action that could

significantly affect the quality of the human environment. Others

include the regulatory analysis process pursued by Federal agencies

(Executive Order 12866; 58 FR 51735, October 4, 1993), and decision

processes of public and professional bodies, such as public utility

commissions and professional medical groups. However, in making these

recommendations EPA does not propose to specify how or by whom

justification should be determined, but simply that the detrimental

effects of radiation, as well as other detrimental effects, should be

considered along with the benefits in any situation where an initial

decision is being made that involves significant exposure of the

general public to radiation.

Recommendation 2

A sustained effort should be made to ensure that doses to

individuals and to populations are maintained as low as reasonably

achievable.

The idea that exposure to radiation should be kept to a practical

minimum became a basic requirement in radiation protection early in the

century, shortly after the recognition that harm from radiation is not

limited to the skin damage that occurs at relatively high doses. The

concept was first applied to exposure of individual workers, primarily

in medical and research applications, since early uses of radiation did

not involve large populations. Later, after the commencement of nuclear

weapons testing and introduction of the widespread use of nuclear

power, it was applied to the exposure of populations--first to

safeguard the genetic pool and, later, after the assumption that cancer

induction is a stochastic process became accepted as a prudent premise,

also to reduce the presumed incidence of cancer. The requirement is now

taken to be the logical and necessary consequence of the assumption of

a linear relationship between exposure to radiation and the risks of

cancer and hereditary effects at the dose levels addressed by these

recommendations.

The phrase ``as low as reasonably achievable'' (ALARA) is used to

designate a general principle that exposure to radiation should be

controlled so as to achieve the lowest level reasonably attainable. The

1960 FRC guidance applied the concept to keeping dose to the individual

as low as practicable, and expressed it as a responsibility to be

carried out by the user of radiation. In these proposed recommendations

the ALARA principle is broadened to apply to collective doses in

populations as well, and in this broader application serves as a

principal basis for the implementation of ALARA through regulatory

practice. This use of the ALARA principle is customarily designated

``optimization'' of radiation protection. Optimization may be carried

out through regulatory determinations for whole classes of similar

sources, as in the establishment of standards for environmental

releases from nuclear power facilities, or, more directly, in the

determination of operating requirements for a specific facility.

Depending on the nature of the source, optimization may involve use of

simple or complex decision tools for balancing public health and

economic concerns to determine the optimal level of control. The basic

elements required for optimization are the values placed on avoiding

the estimated health detriments and the direct costs of control, as a

function of various levels of protection. In reaching a final

optimization determination, however, a variety of other economic and

societal factors may also have to be considered, such as the

distribution of health detriment over populations and over time, and

the technical feasibility and overall economic impact of controls. In

rare cases, the optimization process could result in the need to make

tradeoffs between larger doses to a few individuals (within the limits

specified in Recommendations 3 and 4) and many small doses in large

populations.

At the dose levels involved in the comparison of alternatives for

determining ALARA levels, linearity is assumed, and effects on public

health may be estimated from the collective dose in populations. In

cases where it is necessary to estimate the total public health

detriment from long-lived radionuclides, collective dose will often

have to be projected into the future, or in distant populations.

Regulatory decisions on ALARA levels should take into account such

projections when their contribution is both a significant part of the

total collective dose from the activity under examination and its

uncertainty is not large compared to the differences in collective dose

among the alternatives being examined. In some cases, it may be

appropriate to estimate effects on public health as a function of time

or distance, and to take their distribution in time or distance into

account in decisionmaking. However, it will never be appropriate to

apply an arbitrary cutoff to such projections based solely on the level

of dose to individuals, or on the distance from the source or in time;

such cutoffs would have the effect of preempting the decision-making

process before the magnitude and distribution of the avoidable impact

on health has been estimated.

In some situations, a decision to refrain from applying controls

may be the appropriate outcome of an ALARA determination. Such a

finding for an individual practice, or for a group of practices meeting

specified requirements, may be used as one criterion for exemption from

regulatory control. However, in addition to a finding that the total

health detriment in populations is not large enough to justify control,

it is also necessary to ensure that individual exposures are

sufficiently small, in view of the stipulations of Recommendation 4,

not to warrant regulation. Exemptions that satisfy each of these

criteria would be consistent with these proposed recommendations.

Although the ALARA principle is relevant to a wide variety of

radiation protection activities, these tend to fall into two general

categories. The first is that emphasized above, the establishment of

regulatory levels of control over individual sources or categories of

sources by Federal (or State) agencies. The second, and equally

important, is making management decisions in day-to-day operations at

facilities where ionizing radiation or radioactive materials are

present. The selection of regulatory limits for facilities, as well as

the day-to-day management of sources, in a manner consistent with the

ALARA principle are discussed further in connection with Recommendation

4.

Recommendation 3

The preceding recommendations address the need for justification

and optimization of activities that involve exposure of the general

public. The third basic radiation principle, limitation of maximum dose

to individuals, is addressed by the next two recommendations.

Recommendation 3 limits the sum of doses to any individual from all

radiation sources combined, through the Radiation Protection Guide

(RPG) for the general public; and Recommendation 4 addresses limitation

of doses from individual sources, through the establishment of source-

specific authorized limits.

The RPGs established in 1960 and 1961 consist of separate limits on

dose to the whole body and bone marrow (0.5 rem in a year, each), the

thyroid and bone\18\ (1.5 rem in a year, each), and the gonads (5 rem

over 30 years, average in the U.S. population). Those recommendations

(except that for the gonads) were based on the concept of limiting the

dose to the most critically exposed organ of the body.\19\ That is, it

was assumed that if dose to the critical organ was limited to an

acceptable level, then doses to other parts of the body would also be

acceptably low. One consequence of this approach is that exposure of

the body to external sources of radiation and exposure to internal

radioactivity are addressed by separate limits, and therefore the risks

from such exposures can be additive. Further, when several different

organs are exposed to internal radiation simultaneously, only the part

of the body receiving the highest dose relative to its RPG is decisive

for limiting the dose. That is, the risks associated with exposure of

other parts of the body are not considered in applying a dose limit

based on the critical organ approach. The 1960 limit for dose to the

gonads was based on an entirely different consideration, that of

limiting the incremental rate of mutation in the entire genetic pool of

the U.S. population. The incremental level of mutation deemed

unacceptable was on the order of a few per cent.

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\18\The guidance also included an approximately equivalent RPG

for bone in terms of radium-226 in the adult skeleton (0.003

micrograms).

\19\This was an incomplete set for this scheme of protection,

since many relevant parts of the body were not assigned RPGs. The

1960 RPGs for workers, by contrast, did comprise a complete set,

and, for the general public, the missing values for other parts of

the body were generally taken as \1/10\ of the corresponding

occupational values.

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These recommendations would replace the system described above with

the risk-weighted dose limitation system introduced by the ICRP in

1977\6\. The ICRP system takes into account the individual contribution

of each exposed part of the body to total risk. It does so by assigning

to each organ or tissue of the body a weighting factor that is

proportional to the risk per unit dose of inducing cancer or, for the

reproductive organs, to the risk per unit dose of inducing hereditary

effects in offspring. The risk limit is then expressed in terms of the

sum of weighted dose equivalents to all parts of the body, a quantity

called the ``effective dose equivalent'' (EDE).\20\ A limit in terms of

the EDE therefore reflects both the distribution of doses among the

various organs and tissues and their assumed relative sensitivities to

cancer and hereditary effects. Further, the EDE does not differentiate

exposures from external and internal sources; it includes both.

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\20\The weighting factors are normalized so that the risk

associated with a given EDE is equal to that from a uniform dose of

the same magnitude to the whole body.

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The effective dose equivalent is defined formally in footnote (b)

to Recommendation 3 and proposed weighting factors are listed in Notes

5 and 6, in the formal statement of proposed recommendations at the end

of this notice. These factors reflect the organ-specific risks of

lethal cancer, and, for the reproductive organs, the risk of serious

hereditary effects in the first two generations of offspring. They are

the same weighting factors as those adopted in Federal guidance on

radiation protection for workers in 1987. Although our current best

estimates for these effects on health would lead to somewhat different

values, the differences are sufficiently small that new weighting

factors are not proposed as part of these recommendations. The Agency

has made this choice for several reasons. First, it should be noted

that changes in the weighting factors, based on new estimates for

mortality, would have no effect on the level of risk represented by a

given dose to the whole body, since the sum of the weighting factors

is, by definition, normalized to unity. (If these factors were adjusted

to take into account non-lethal cancers or other factors such as age at

incidence the risk level could change, but, for the same reason, this

change would be small.) Thus, the general level of risk achieved would

not be affected. Second, the ICRP has recently published revised

weighting factors that, in addition to incorporating updated

information on risks of mortality, also consider other factors such as

morbidity, i.e., the risk of non-lethal cancer (but do this without

changing the recommended dose limit).\7\ We are reviewing those

weighting factors, as well as our own estimates of organ-specific risk

factors. Finally, extensive new tabulations, for each of over 700

radionuclides, of dose factors for various chemical forms and routes of

exposure have recently been completed using the existing weighting

factors.\21\ Regulations using these dose factors are being implemented

by EPA, NRC, and DOE. Changing the weighting factors for many of these

regulations will require formal rulemaking. EPA will keep these

considerations under review, will continue to review the choice of

weighting factors as new information becomes available, and will issue

guidance on improved weighting factors from time to time, following

review by and consultation with affected Federal agencies.

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\21\These are specified in Note 7 to the Recommendations.

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Recommendation 3, which specifies the proposed new RPG for the

general public, consists of three parts. We first set forth the text of

the recommendation and some explanatory details, and then discuss the

basis for the choice of the value of the RPG and other related matters.

The first part of Recommendation 3 reads:

The combined radiation doses incurred in any single year from

all sources of exposure covered by these recommendations should not

normally exceed a Radiation Protection Guide of 1 mSv (100 mrem)

effective dose equivalent to an individual. The Radiation Protection

Guide applies to the sum of the effective dose equivalent resulting

from exposure to external sources of radiation during a year and the

committed effective dose equivalent incurred from the intake of

radionuclides during that year.

This recommendation would replace the 1960 and 1961 RPGs for dose

equivalent to the whole body and specified parts of the body by a

single RPG of 1 mSv (100 mrem) effective dose equivalent in a year. In

so doing, it would create a single limit for combined dose from

external and internal radiation.

Certain radionuclides, if inhaled or ingested, may remain in and

continue to irradiate the body for many years. This proposed

recommendation incorporates the use of ``committed'' dose into guidance

for the general public (this concept was introduced into Federal

radiation protection guidance for workers in 1987). It provides that

Federal agencies should base control of annual intake of such

radionuclides upon the future dose that may result over time (that is,

the committed dose), not just the ``annual'' dose accrued during the

first year following intake. This would assure that, in regulating

annual intake of such materials by members of the public, account is

taken of the additional risks committed from doses that will be

delivered in future years. The standard period for which committed dose

is calculated is proposed to be taken as 50 years, as in the Agency's

previous recommendations for workers. Although there are a few

radionuclides from which doses can accrue for longer periods, the risk

associated with intake of such radionuclides will be conservatively

estimated, compared to the risk from a comparable external dose,

because of the combined effect of the distribution over time of

committed dose and the latency period for expression of cancer.

The proposed RPG is expressed in terms of both the new special SI

unit ``sievert'' and the historically-used special unit ``rem.'' It is

not the intent of these recommendations to express a preference for

either system of units, but merely to recognize the existence and

acceptability of both. Federal agencies would be free to use either

unit under these recommendations, but should specify conversion factors

between the two systems in new regulations.

The second part of Recommendation 3 reads:

The Radiation Protection Guide may not be reasonably achievable

in some unusual situations. It may be exceeded temporarily in

situations that are not anticipated to recur chronically and when

Recommendations 1 and 2 are satisfied, provided that the radiation

dose incurred in any year does not exceed 5 mSv (500 mrem) effective

dose equivalent.

It is not anticipated that this provision would be used frequently.

In the past, doses to members of the public at or near such levels have

been uncommon, and the Agency expects this to continue to be true. We

have identified two examples of situations in which such doses are

known to occur now, and might reasonably be permitted to exceed the

RPG. The first is through the incidental exposure of a family member,

household member, or friend to a patient being treated (or diagnosed)

using radioactive materials, for certain medical procedures (primarily

in the treatment of thyroid cancer using\131\I). The second involves

the exposure, in some unusual cases, of individuals living near

radioactive contamination that has not yet been cleaned up. This almost

invariably involves naturally-occurring materials, often from mining or

milling operations. In situations where temporary relocation is not an

acceptable alternative it may not be practical to complete such cleanup

without exposing a few members of the public to doses exceeding 1 mSv

(100 mrem) in a year. This provision is not intended for use as a limit

in dealing with short-term emergency situations arising from nuclear

accidents; these are governed by the Protective Action Guides for

nuclear incidents (EPA-520/1-75-001-A).

The third part of Recommendation 3 reads:

Continued exposure of an individual over substantial portions of

a lifetime at or near the level of the Radiation Protection Guide

should be avoided. This will normally be achieved through

conformance of individual sources to Recommendations 2 and 4.

In recommending an RPG of 1 mSv (100 mrem) in a single year, it has

been necessary to balance the practical regulatory need for an RPG

expressed in terms of annual dose against the public health objective

of adequately limiting lifetime risk. We anticipate that satisfying the

criteria specified in Recommendations 2 and 4 will almost invariably

achieve this objective. However, in the unlikely event that

circumstances were such that continued exposure at or near the RPG over

substantial portions of a lifetime could occur, this portion of

Recommendation 3 explicitly expresses the criterion that chronic

exposure at such levels should be avoided.

Basis for the Radiation Protection Guide

In the latter part of the twentieth century, society has become

increasingly unwilling to accept risks imposed by activities that

produce environmental pollutants. Many of the benefits of

industrialized society, however, are brought about by activities that

carry with them some unavoidable elements of risk. This is especially

the case for so-called ``non-threshold'' pollutants like radiation, for

which it is assumed that there are no risk-free levels. The risk to an

individual from exposure to ionizing radiation, as discussed above, is

assumed to depend linearly upon the radiation dose, without a

threshold. Under current guidance the average member of the public now

receives, from all the sources to which that guidance has consistently

been applied, only a very small dose--less than 0.01 mSv (1 mrem) in a

year.\22\ The average risk of fatal cancer incurred from such an

exposure is estimated to be somewhat less than 5 in ten million.

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\22\During the period 1960 to the present, the current RPG has

not consistently been applied to exposure due to natural sources.

The primary examples are building materials and radon in domestic

groundwater supplies; these contribute additional average effective

dose equivalents to the U.S. population of 0.035 mSv (3.5 mrem) and

0.01-0.06 mSv (1-6 mrem), per year, respectively. Tobacco smoke

contributes a further, at present incompletely characterized, dose.

(These estimates are derived from Ionizing Radiation Exposure of the

Population of the United States, National Council on Radiation

Protection and Measurements Report 93, Bethesda, MD (1993).)

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The cumulative risk to society associated with the variety of

current uses of radiation is now governed by the dual requirements that

each use be justified and that its effect on public exposure minimized

by optimizing radiation protection. These requirements would be

continued and strengthened under proposed Recommendations 1 and 2.

Typically, this would result in a distribution of annual doses from

each source of radiation exposure ranging from zero for most members of

the population to a maximum value (established under Recommendation 4)

accruing to a small number of individuals. The RPG serves as an upper

bound on the highest doses resulting from the sum of all such

distributions. As such, it acts as a limit on the annual increment of

risk, now and in the future, to the theoretically most exposed

individual with typical consumption and other relevant behavior habits.

In selecting the proposed value for the RPG the Agency has had to

consider a number of judgmental factors: the relation between a limit

on annual dose and the implied lifetime risk; the degree of protection

achieved through the application, by regulatory authorities, of

optimization to the derivation of source limits, as well as their

consideration of the various possibilities for multiple exposure to

current and future sources, under Recommendation 4; and, finally, the

record to date on the operational application of ALARA (i.e., the

difference between source limits and the doses actually experienced).

It is anticipated that the proposed RPG, applied in the context of

these proposed recommendations, would, under most circumstances, result

in lifetime risks to the most exposed members of the public from man-

made radiation in the environment of less than one in ten thousand.

This expectation is based on past experience under current radiation

protection guidance, cited above, coupled with the improvements in

protection proposed here--most particularly those proposed under

Recommendations 2, 3, and 4. Recommendation 2 strengthens the

requirement that doses be maintained as low as reasonably achievable;

Recommendation 3 reduces the RPG; and Recommendation 4 requires source-

specific limits that take into account the present and future potential

for doses from other sources (and are therefore normally only a

fraction of the RPG). EPA has, in a number of previous actions,

concluded that a lifetime risk level no greater than about one in ten

thousand provides an acceptable level of protection. These include the

National Emission Standards for Hazardous Air Pollutants (NESHAPs), the

National Primary Drinking Water Standards, and the Agency's guidelines

for site-specific risk management under the Comprehensive Environmental

Response, Compensation, and Liability Act (``Superfund''). These

recommendations propose that this level of protection is also

appropriate for application in this Federal Radiation Protection

Guidance for Exposure of the General Public and would be achieved

through the cumulative application of these recommendations.

In addition, the proposed five-fold reduction in the RPG and the

accompanying requirement that it be applied to the sum of external and

committed internal doses would assure that maximum risks permitted to

even the most highly exposed individuals are greatly reduced, compared

to those permitted under the current RPGs. Although not many people are

exposed near the RPG, a few cases of such high risks do now exist.

These are usually associated with technologically enhanced exposure to

natural radioactive materials. Examples include phosphate mining

residues in Idaho and Florida, radium processing wastes in New Jersey,

Illinois, and Colorado, and uranium mill tailings at publicly

accessible locations in a number of western states. Under the current

RPGs, annual doses due to external exposure up to 5 mSv (500 mrem) are

permitted, in addition to organ doses from internal exposure up to 15

mSv (1500 mrem), depending on the organ and the radionuclide. Such

doses imply lifetime risks up to 250 in one million for each year of

external exposure, and up to 40 in one million for each year of

internal exposure. The proposed RPG of 1 mSv effective dose equivalent

would limit the incremental lifetime risk associated with each year of

combined external and internal exposure to 50 in one million, a

significant reduction in risk.

Finally, the Agency notes that the proposed RPG is consistent with

levels found acceptable and in use by the international community. A

value of 1 mSv per year is recommended as the upper bound on doses to

members of the public by both the ICRP and the International Atomic

Energy Agency, and is in common use throughout the world.

To provide a perspective on the above levels of risk, it may be

noted that the average American is exposed annually to an effective

dose equivalent of about 3 mSv (300 mrem) from natural background

radiation, including an average contribution of about 2 mSv (200 mrem)

from radon in homes. This exposure is three times the proposed RPG, and

each year's exposure corresponds to an incremental lifetime risk of 150

in one million. Although the average level of exposure to natural

background provides perspective, it does not, however, provide a

justification for the RPG, since it represents an uncontrollable source

of risk, and the RPG applies to controllable sources.

The levels of risk assumed to be associated with radiation exposure

may also be compared to involuntary and voluntary risks actually

incurred in common activities. For example, the essentially involuntary

risk of dying of a household accident averaged about 110 in a million

per year, between 1980 and 1990, and the average probability of dying

of an automobile accident in the same decade, a voluntary risk, was 240

in a million per year. We emphasize that all of these examples are

provided for perspective only, and that the existence of other risks,

voluntary or involuntary, is not a justification for any particular

incremental radiation risk.

EPA recognizes that some of the assumptions that underlie the

proposed RPG are not readily quantified, or are based on experience

that may not accurately predict the future. We will continue to review

exposure of the general public, with a view to initiating

recommendations for any further modification of these recommendations

that may be warranted to ensure that low risks to individuals are

maintained.

Other Matters Related to the Radiation Protection Guide

In developing these recommendations, EPA also considered risk to

the unborn from exposure of pregnant women. It is clear that, in

general, the fetus is more sensitive to many environmental carcinogens,

mutagens, and teratogens than are adults, because the rate of cell

division in their developing organs is far greater. This appears to be

the case for radiation as well, which can act in any of these three

ways. Of these risks, the most important at the levels of exposure

addressed by these recommendations is mental retardation due to

exposure to radiation during the eighth to fifteenth weeks of

gestation, as discussed earlier.

In considering the importance of the risk of mental retardation to

the choice of the RPG, we note that the sensitive period for inducing

this effect represents a very small part (0.2%) of a normal lifetime,

the time span addressed by the risk limitation contemplated by these

recommendations. This sensitive period should be considered in

conjunction with the observation that sources governed by these

recommendations typically yield exposure that is uniformly distributed

in time, and almost never yield high-level, short-duration doses.

(Accidents are not addressed by this guidance.) Based on these two

observations, coupled with the numerical values for radiation risks

cited earlier, EPA concludes that the risk of mental retardation from

the relatively small exposure of the unborn that would accumulate

during the short period of sensitivity before birth will be smaller

than the risk of cancer associated with the very much longer period

following birth, during which time a relatively much larger exposure to

sources governed by these recommendations could accumulate. EPA

believes, further, that it is not appropriate to base a general limit

for members of the public on the highly unlikely circumstance that the

entire RPG is delivered during the short period of significantly

elevated susceptibility of the unborn. We conclude, therefore, that

these proposed recommendations would provide adequate protection of the

unborn without specifying a separate limit specifically for this

purpose.

An opposite situation is posed in considering the risk to members

of the population who are within one or two decades of the end of a

normal lifetime. In this case the risk, instead of being higher, is

lower. The risk of cancer in this population approaches being an order

of magnitude smaller than the risk to an average member of the

population, and the risk of genetic consequences is normally no longer

present. EPA has not proposed a higher RPG for this population because,

as noted for the case of the unborn, these recommendations are based on

limiting the risks that accrue over a lifetime, not on a yearly basis.

The RPG is expressed as an annual limit simply for ease of

implementation. We also note that a limit that was different for

different ages of members of the public would pose severe

implementation difficulties.

Implementation of measures for assessment and control of internal

exposure to radionuclides commonly makes use of intake-to-dose

conversion factors. EPA has previously tabulated such values for use in

implementing the Federal Guidance for Protection of Workers, in Federal

Guidance Report No. 11, Limiting Values of Radionuclide Intake and Air

Concentration, and Dose Conversion Factors for Inhalation, Submersion,

and Ingestion (EPA-520/1-88-020). The dose conversion factors in this

report and its subsequent editions also apply to intake of

radionuclides by members of the general public. For external sources,

exposure-to-dose conversion factors are tabulated in Federal Guidance

Report No. 12, External Exposure to Radionuclides in Air, Water, and

Soil (EPA 402-R-93-081).

These dose conversion factors are appropriate for application to

any population adequately characterized by the set of values for

physiological parameters developed by the ICRP and collectively known

as ``Reference Man.''\23\ The actual dose to a particular individual

from a given intake is dependent upon age and sex, as well as other

characteristics. As noted earlier, implementing limits for the general

public expressed as age and sex dependent quantities would be

difficult. (Clearly, it would be impracticable to conduct an annual

survey of age and sex at every location of a potential source of public

exposure.) More importantly, the variability in dose due to these

factors is comparable in magnitude to the uncertainty in our estimates

of the risks which provide the basis for our choice of the RPG. For

this reason EPA believes that, for the purpose of providing radiation

protection under the conditions addressed by these recommendations, the

assumptions exemplified by Reference Man adequately characterize the

general public, and a detailed consideration of age and sex is not

generally necessary. The most obvious exception is for large doses

delivered in a short period of time, as in an accident, for which case

the appropriate response is addressed by separate EPA recommendations

(EPA-520/1-75-001-A).

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\23\ICRP No. 23 Report of the Task Group on Reference Man, 1974.

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The proposed RPG is sufficiently small that the dose any organ

might receive will be far below threshold levels for non-stochastic

health effects (i.e. effects on health, such as burning of the skin,

cataracts, impairment of fertility, and more serious effects which can

lead to early death, all of which only occur when threshold levels of

dose that are greater than 0.5 Sv (50 rem) are exceeded). That is,

adequate protection of every organ from non-stochastic health effects

is automatically ensured by the proposed RPG. These recommendations

therefore do not include separate limits to prevent the occurrence of

non-stochastic effects.

The sum of weighted organ doses that comprises the effective dose

equivalent does not include an allowance for cancers induced by

irradiation of the skin. In some circumstances, however, in the

assessment of total health detriment in populations, dose to the skin

may be large enough to warrant consideration of fatal cancers due to

skin dose. These proposed recommendations provide for adding to the

effective dose equivalent a term that is the product of the dose

equivalent to skin (averaged over the entire skin surface) and a

weighting factor of wskin=0.01 in such cases.

Recommendation 4

Recommendation 4 consists of two parts. The first reads:

Authorized limits for sources should be established to ensure

that individual and collective doses in current and future

populations satisfy the objectives of this guidance. These limits

may be developed for categories of sources or for specific sources.

Authorized limits for sources should normally limit doses to a

fraction of the Radiation Protection Guide for all sources combined.

Authorized limits are standards, regulations, technical

specifications, or other requirements established by a responsible

authority to ensure that the objectives of this guidance with respect

to limitation of doses will be satisfied. Implementation of the ALARA

requirement (Recommendation 2) will involve consideration of collective

doses to populations,\24\ of control mechanisms, and of other factors

that will differ for each category of sources, and will usually lead to

control levels that result in doses to individuals less than the RPG

(Recommendation 3). However, there are many different categories of

activities using radiation that can lead to exposure of members of the

public. These currently include medical uses of radiation and their

supporting activities; nuclear electric power facilities and their

supporting fuel cycle facilities; research and industrial users;

weapons production, storage, and disposal facilities; technologically-

enhanced exposure to natural radiation sources; consumer products;

space applications; disposal sites for radioactive wastes; and

decommissioned sites at which radioactive materials were formerly used.

It is therefore also necessary to ensure that total doses to

individuals, who may be exposed not only to more than one source in a

given category in a few cases, but more often to a number of different

categories of sources at one time, are not likely to exceed the RPG. It

is not intended that this objective be implemented through

apportionment of the RPG among categories of sources; this would be

impracticable. Rather, this consideration, which must encompass the

potential for doses to the general public both now and in the future,

will necessarily be a broad judgment, based on general observations of

the characteristics of existing activities, projections for their use

in the future, and the potential for presently unidentified future

uses.

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\24\These recommendations are not intended to require numerical

limits for collective dose. Although the determination of ALARA

levels necessarily involves optimization of the collective dose, the

regulations that implement these levels can be expressed in terms of

individual or collective dose, total or concentration of activity

released, installation and use of specified controls, or any other

specification that the regulatory authority finds appropriate.

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To implement these objectives, authorities responsible for limiting

exposure of the public should govern sources through use of

``authorized limits'' established either for categories of similar

sources or for specific sources. In establishing these authorized

limits, since the ALARA process considers actual costs and capabilities

of controls, it is important that assessments of doses to individuals

and populations be carried out realistically and comprehensively. Such

assessments should contain neither unnecessarily unrealistic

assumptions that overestimate doses nor omit any significant

contributions to risk or detriment, since either of these would

invalidate the ALARA determination. Further, authorities should

consider, in addition to the design capabilities of facilities for

control of releases, expected departures from anticipated design

performance. Finally, in the case of authorized limits established for

broad categories of sources, the judgments will often necessarily be

broad and may lead to somewhat higher values, with further

implementation of the ALARA process left to management of the

individual sources within a category.

Authorized limits currently exist for a wide variety of sources, at

levels that are fractions of the proposed RPG. For example, in 1977 EPA

established general limits for dose received from all radionuclides,

combined, via all exposure pathways, combined, from most facilities

involved in the nuclear fuel cycle combined, including power reactors,

in 40 CFR Part 190. The principal limit, 25 millirem (0.25 mSv) per

year to the whole body, is 25% of the proposed RPG. Additional site

specific limitations are established, for example, by the Nuclear

Regulatory Commission in license conditions for individual commercial

reactor sites, or in requirements for specific types of facilities,

such as low level waste sites in 10 CFR Part 61. EPA has recently

established source-specific limits for doses from all radionuclides,

combined, via all air pathways from individual sources of radionuclide

emissions, including all Federal facilities, in 40 CFR Part 61. These

generally require limiting doses to 10 millirem (0.1 mSv) per year

effective dose equivalent, or 10% of the proposed RPG. Finally, the

national drinking water standards at 40 CFR Part 141 limit doses from

water at the tap to 4 millirem (0.04 mSv) per year whole body or organ

dose from all man-made radionuclides, or 4% or less of the proposed

RPG. In each of these cases, the regulatory process, under the current

recommendations, supplemented in some cases by additional statutory

requirements, has resulted in requirements ensuring that maximum dose

to individuals from a specific source or category of sources is a small

fraction of the proposed RPG for dose from all sources combined.

Although this situation is anticipated to continue, we believe it is

prudent to note explicitly that authorized limits should normally

satisfy this condition.

Once such authorized limits are established, it will no longer be

necessary to further evaluate contributions to doses from any other

source as part of the management of the operations of a specific

source. These requirements thus serve to avoid the need to perform

detailed, and in some cases very difficult to validate, evaluations of

the combined incremental doses from other sources at individual sites.

Conversely, if these requirements are exceeded (or are absent), then

such evaluations may be necessary to assure conformance to the RPG

(Recommendation 3).

The second part of Recommendation 4 reads:

Sources should be designed not to exceed authorized limits, and

should be operated so as to maintain doses to members of the general

public as low as reasonably achievable within such limits.

The ALARA principle applies not only to the establishment of

authorized limits, but also to detailed management of facilities where

sources of radiation are prepared, employed, stored, or transported.

This is necessary and appropriate because authorized limits must

usually provide flexibility for anticipated deviations from design

performance, and controls usually can perform better than their design

limits. Thus, exposure of the general public, even if a source conforms

to authorized limits, will not be ALARA when lower exposures are

reasonably achievable.

As exemplified by the performance of many facilities over the past

two decades, doses to the public usually can be maintained far below

authorized limits through responsible and skillful control of radiation

sources. This has required careful management and supervision of

radiation protection activities, including the choice and

implementation of radiation control measures for sources of exposure of

members of the public, training in procedures to control such exposure,

and monitoring, assessment, and reporting of exposure levels and doses

at appropriate on-site and off-site locations. The routine management

of a facility and decisions on how, or whether, particular actions

should be carried out can, in the aggregate, be as (or more)

significant for radiation protection of the public as the design of the

facility and choice of its authorized limit.

The selection of authorized limits and the application of the ALARA

principle to operations requires technically informed judgments. Thus,

the practice of ALARA must be the responsibility primarily of those

persons who control and manage sources of radiation under the oversight

of the responsible public authorities; that is, it should not be the

responsibility of individual members of the public, who are not

familiar with radiation protection practices. For example, consumer

products containing radioactive materials, and instructions for their

use and disposal, should be designed to maintain radiation doses that

are ALARA, and members of the public who use them should not have to

rely upon their own judgment on this issue. The ALARA principle must be

implemented by those who are directly responsible for radiation

protection, or who are otherwise professionally responsible for health,

safety, and environmental protection aspects of radiation sources.

Recommendation 5

Risks associated with exposure of the general public to

radiation that may occur due to Federal agency decisions, and the

policies upon which these decisions are based, should be made known

to the public in a timely fashion as part of the decision process.

The degree of detail and type of information made available should

be appropriate to the potential radiation exposures involved.

Information on risks should encompass estimates of the risks of

effects on health over time, and of the uncertainties in such

estimates. Information on policies should include reference to this

Federal radiation protection guidance for the general public and

other relevant Federal policies.

To judge the validity and acceptability of decisions about Federal

activities which not only bring benefits but also pose risks, the

public requires clear and, to the extent possible, quantitative

information. In the case of proposed Federal actions involving exposure

to radiation, this includes information on the biological effects of

radiation, on the levels of risk associated with exposures that may

result from the actions, and on the Federal policies that underlie the

action.

Requirements for the development and presentation of these kinds of

information may be found in the National Environmental Protection Act

(NEPA), 42 U.S.C. Secs. 4231 et seq.; Title III of the Superfund

Amendments and Reauthorization Act (SARA), 42 U.S.C. Secs. 9601 et

seq.; the Administrative Procedure Act, 5 U.S.C. Secs. 551 et seq.; and

in other legislation. Such information serves to assist the public in

becoming constructively involved in the decision process and in

influencing the public policy issues that affect them.

It is the purpose of this recommendation to ensure that, when

Federal agencies formulate policies and make decisions that influence

the exposure of the general public, information that will adequately

inform the public during the decision-making process is made available

by them in a timely manner. Although it is not intended to require

general dissemination of information concerning ongoing operations, nor

to require major public information distribution efforts, such

activities are encouraged whenever it is reasonable to carry them out.

Recommendation 6

Assessments and records appropriate to the origin and magnitude

of expected doses and the exposed population should be performed and

maintained to demonstrate conformance with requirements which

implement these recommendations. The types and accuracy of methods

and procedures used in these assessments should be reviewed

periodically to ensure that they are appropriate and are being

competently applied.

Control of exposure of the public is normally ensured through

analysis of releases from sources and modeling of environmental

transport to hypothetical ``critical groups'' of the general public

assumed to receive the greatest exposure. Unlike the situation for

workers exposed occupationally, it is usually neither appropriate nor

feasible to physically monitor doses to individual members of the

public. Such dose rates and concentrations may be determined by

measurement of radioactive effluents, mathematical modeling of the

dispersal of radionuclides in the environment, or both.

Assessments and records required to ensure conformance with these

recommendations will vary, depending upon the nature of the source of

exposure. Responsible authorities will have to determine what is needed

to ensure that exposures of members of the public actually are

maintained within authorized limits and are ALARA. In some cases,

comprehensive radiation assessment programs will be needed which

include trained personnel, facility and environmental measurements,

audit procedures, and maintenance of records. In many cases

conservative assumptions, such as the assessment of doses to a

hypothetically most exposed individual, may be used to simplify the

demonstration of compliance. In still others, simple operational

procedures will suffice.

This recommendation intentionally allows flexibility with respect

to what should be assessed and recorded, so that the responsible

authorities will be able to design optimal programs for each situation.

This is intended to avoid, in particular, burdensome requirements for

situations in which individual doses and detriments to populations are

very low. At the same time, assessments and recordkeeping must be

adequate to document that requirements which implement these

recommendations have been satisfied.

Recommendation 7

Exceptions to Recommendation 3 for planned exposure to radiation

should be made only for highly unusual circumstances, and only when

the Federal agency having jurisdiction has carefully considered the

reasons for making them in light of these recommendations. If

Federal agencies authorize any exception to these values, they

should make it a matter of public record.

This proposed guidance applies to emissions and exposure of the

general public under normal circumstances. In developing these

recommendations, EPA has considered situations that might normally

arise. It is not possible to foresee all contingencies, however, and

highly unusual situations may occur when exceptions to the limiting

values of Recommendation 3 are appropriate. This recommendation

provides that if such circumstances should arise, Federal agencies

should carefully consider the balance of the guidance, including the

information requirements of Recommendation 5, and make a public record

of any authorized exception to Recommendation 3 (e.g., by publishing a

notice in the Federal Register or in a local newspaper of general

circulation).

Implications of these Recommendations

It is expected that these proposed recommendations could be

implemented relatively easily, since most of them are already, in large

part, in effect. For example, most sources are already regulated in

such fashion that exposures of members of the public are a small

fraction of the proposed Radiation Protection Guide of 1 mSv (100 mrem)

in a year, and we are aware of no regulated sources that exceed the

proposed RPG. Perhaps the most significant implication of these

recommendations would be to promote consistency between Federal

agencies by clarifying the basic considerations to be taken into

account in the development of new standards and regulations, and in

their implementation. The recommendations modernize the methodology for

expressing dose, and clarify the relationship of the RPG to standards

and regulations for sources, as well as the various applications of the

principle that doses should be maintained ``as low as reasonably

achievable,'' and they provide, for the first time as a part of their

basis, numerical estimates of the various risks from low levels of

ionizing radiation.

Implementation of the proposed recommendations would require only

minimal changes in Federal regulations, and should be achievable over a

short period of time. Many of the changes called for are largely

already well under way, major examples being the revisions recently

made by the Department of Energy in their Order No. 5400.5, and those

recently promulgated by the Nuclear Regulatory Commission in 10 CFR

Part 20. It is expected that Federal agencies will have little

difficulty in identifying and correcting any remaining problem areas,

and in providing necessary flexibility and transition periods, to avoid

undue impacts that might inhibit prompt implementation of new guidance.

We note in passing that in some cases (notably in the regulation of

exposure of the public from the transportation of radioactive

materials) conformance to existing guidance is based upon the

assumption of ``reasonably foreseeable'' scenarios for the spatial and

temporal relationship between radioactive materials and members of the

public, and that because of this assurance the RPG will never be

exceeded cannot be given with absolute certainty. These recommendations

do not propose any changes in this regard, and EPA expects that in such

cases the same approach to protection would continue to be employed to

achieve conformance to these new recommendations.

The anticipated costs of implementing these recommendations are

primarily those that would be incurred by the various agencies in

modifying their own regulations. These are not expected to be

substantial, since most of the necessary methodological changes have

already been implemented in connection with the revised Federal

guidance for occupational exposure issued in 1987. Unlike the situation

for occupational exposure, where the need to reduce the doses received

by a few highly exposed workers to conform to lower limits may lead, in

some cases, to the hiring and training of additional workers, there are

few direct implementation costs involved here, since most sources are

already regulated to well within the proposed new requirements.

This guidance would not supersede any statutory responsibilities of

the agencies that would implement these recommendations, and in some

situations application of these recommendations could be superseded by

specific statutory requirements. In addition, it does not create any

new authority. As noted earlier, it is the purpose of this Federal

guidance to provide a common framework to help ensure that the

management of exposure to radiation in the United States is consistent

and adequately protective. This can be carried out through regulations

applicable to the public sector, through orders applicable to the

internal operations of Federal agencies, through guidance, or by any

other practicable means. The individual Federal agencies, based on

their statutory and administrative mandates, have determined, and would

continue to determine, the details of specific regulations, orders,

guidance, or other actions, the parties responsible for implementing

them, and the means to do this.

The proposed recommendations differ from current guidance in

significant ways. The Radiation Protection Guide for maximum radiation

dose to a member of the public in a year is reduced by a factor of

five, from 500 mrem to 1 mSv (100 mrem). The concept of risk-based

weighting of doses to different parts of the body is adopted, and the

committed dose is introduced as the primary basis for control of

internal exposure. The RPG now applies to the sum of external and

internal exposure. Increased emphasis is placed on keeping justified

exposure as low as reasonably achievable (ALARA), and on the

comprehensive consideration of doses in populations near and distant,

now and in the future. The establishment of authorized limits for

sources or categories of sources that are derived giving consideration

to the wide variety of potential sources and their future implications

for exposure that, combined, must be maintained within the RPG, and

from the comprehensive application of ALARA, is recommended. The

proposed recommendations recognize, for the first time in this Federal

guidance, the importance of public information and of assessing and

recording public exposures. Finally, these recommendations would bring

U.S. radiation protection policy into conformance with that in general

international use. EPA expects these changes would strengthen the

overall system for radiation protection of the members of the public in

the United States.

These recommendations would replace those portions of current

Federal Radiation Protection Guidance (25 FR 4402) that apply to

protection of the general public from ionizing radiation. It is

expected that individual Federal agencies, on the basis of their

knowledge of specific sources of exposure of the general public, would

use this new guidance as the basis upon which to revise or develop

detailed standards or regulations, to the extent that they have

regulatory or administrative jurisdiction. Pursuant to my

responsibilities under Executive Order 10831, the Atomic Energy Act of

1954, as amended, and Reorganization Plan No. 3 of 1970, I would

propose to keep informed of Federal agency actions to implement this

guidance and to interpret and clarify these recommendations, and, in

consultation with affected Federal agencies, from time to time amend

the clarifying notes to reflect new technical information, as necessary

to promote a consistent and effective Federal program of protection of

the public from radiation.

Request for Comments

EPA requests comments on any and all aspects of these proposed

recommendations. We would, for example, appreciate comment on the

overall approach to protection of the public embodied by these

proposals, which would continue and expand upon the approach

recommended for protection against the effects of exposure to radiation

by national and international professional advisory bodies, and which

has formed the basis for previous guidance to Federal agencies. In

addition to general comments, we are also particularly interested in

commenter's views on the following specific matters:

1. Should EPA consider a lower or higher value for the Radiation

Protection Guide (RPG); e.g., 0.3, 0.5, or 1.5 mSv (30, 50, or 150

mrem)? What would be the rationale for such a value? If a lower value

is adopted would it be necessary to modify Recommendation 4, and, if

so, how could it be modified to retain flexibility to provide for

possible future beneficial uses?

2. Is it necessary to provide, in Recommendation 3, for temporary

exposures as high as 5 mSv (500 mrem). What specific examples of

situations that justify this proposed provision currently exist, or

have a high probability of occurring in the future?

3. Should the guidance recommend a single maximum risk (or dose)

level for individual sources, under Recommendation 4, which would serve

as an upper bound on all ALARA determinations? If this approach were

adopted, would the RPG in Recommendation 3 become superfluous?

4. Should the recommendations provide guidance on the kinds of

situations under which it would be appropriate for a Federal agency to

invoke Recommendation 7. Are there foreseeable situations that require

the existence of this proposed provision?

5. Should EPA initiate proposals to update the weighting factors

for effective dose now. If so, what basis or values for these factors

should we consider?

6. Has EPA correctly characterized the cost of implementing these

recommendations. If not, what specific costs have we not identified,

what is their estimated magnitude, and what is the basis for this

estimate?

7. These proposals do not express a preference between historical

radiation units, commonly used in health physics practice, and the new

system of units (SI) now in scientific and international health physics

use. Should they?

8. These proposed recommendations do not address protection of

animals and plants. Are the proposed levels adequate to protect all

plant and animal species? If not, what level would provide adequate

protection? Is protection at the level of species the appropriate

choice?

EPA will carefully consider all written responses to this request

for comments, and we encourage interested parties to present their

views at the public hearing that will be held on these proposals.

Following these hearings we will, after consulting with affected

Federal agencies, formulate and transmit final recommendations to the

President for revisions to Federal radiation protection guidance for

exposure of the general public.

Dated: December 14, 1994.

Carol M. Browner,

Administrator.

Proposed Recommendations

The following recommendations are made for the guidance of Federal

agencies in the formulation of regulations and conduct of programs for

the protection of the general public from ionizing radiation. Their

objective is to ensure that exposure to ionizing radiation is

restricted to levels that will not produce undue risk to individuals or

undue harm in populations.a The recommendations apply to radiation

exposure other than that from background radiation or received as a

patient in the practice of the healing arts, as a worker, or as the

result of an accident. (See Notes 1 and 2.)

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\a\The term ``risk,'' as used here, means the statistical

probability of harm to the health of an individual from exposure to

radiation. ``Harm in populations'' from exposure to radiation,

called the radiation ``detriment'', means the mathematical

expectation of harm in the population, taking into account the

probabilities and the severities of different deleterious effects.

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1. There should be no exposure of the general public to ionizing

radiation unless it is justified by the expectation of an overall

benefit from the activity causing the exposure. Justified activities

may be allowed, provided exposure of the general public is limited in

accordance with these recommendations.

2. A sustained effort should be made to ensure that doses to

individuals and to populations are maintained as low as reasonably

achievable. (See Note 3.)

3. The combined radiation doses incurred in any single year from

all sources of exposure covered by these recommendations should not

normally exceed a Radiation Protection Guide of 1 mSv (100 mrem)

effective dose equivalentb to an individual.c The Radiation

Protection Guide applies to the sum of the effective dose equivalent

resulting from exposure to external sources of radiation during a year

and the committed effective dose equivalent incurred from the intake of

radionuclides during that year. (See Notes 4 through 7.)

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\b\Effective dose equivalent is a derived quantity defined as

the risk-weighted sum of dose equivalents to specified organs and

tissues.

Dose equivalent is the product of the absorbed dose and a

quality factor which varies with the energy and type of radiation.

In the system of quantities of ionizing radiation historically in

use in the United States, the unit of dose equivalent is the

``rem.'' In the international system (S.I.), the corresponding unit

is the ``sievert'' (Sv). One sievert equals 100 rem.

The effective dose equivalent, HE, incurred in a given

period of time is the sum of the effective dose equivalent,

HE,ext, received from external exposure in that period and the

committed effective dose equivalent, HE,50, incurred from the

intake of radionuclides during that period. That is,

E=HE,ext + HE,50 =T

wt(H,ext + HT,50),

where wT is a weighting factor for organ or tissue T;

HT,ext is the dose equivalent from external irradiation

averaged over organ or tissue T; and HT,50, the committed dose

equivalent, is the sum of all dose equivalnts, averaged over organ

or tissue T, that may accumulate over an individual's anticipated

remaining lifetime (taken as 50 years) from radionuclides retained

within the body. The weighting factors satisfy the condition

T wt = 1.

The word ``dose'', when used alone in these recommendations, is

intended to carry the specific dose unit implied by the surrounding

text.

\c\The term ``individual'' means a typical member of any

critical group of most highly exposed members of the general public;

it refers to persons with typical consumption and other relevant

behavior habits.

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The Radiation Protection Guide may not be reasonably achievable in

some unusual situations. It may be exceeded temporarily in situations

that are not anticipated to recur chronically and when Recommendations

1 and 2 are satisfied, provided that the radiation dose incurred in any

year does not exceed 5 mSv (500 mrem) effective dose equivalent.

Continued exposure of an individual over substantial portions of a

lifetime at or near the level of the Radiation Protection Guide should

be avoided. This will normally be achieved through conformance of

individual sources to Recommendations 2 and 4.

4. Authorized limitsd for sources should be established to

ensure that individual and collective doses in current and future

populations satisfy the objectives of this guidance. These limits may

be developed for categories of sources or for specific sources.

Authorized limits for sources should normally limit doses to a fraction

of the Radiation Protection Guide for all sources combined. (See Note

8.)

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\d\Authorized limits are standards, regulations, or other

requirements established by a responsible authority for categories

of sources or for a specific source.

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Sources should be designed not to exceed authorized limits, and

should be operated so as to maintain doses to members of the general

public as low as reasonably achievable within such limits.

5. Risks associated with exposure of the general public to

radiation that may occur due to Federal agency decisions, and the

policies upon which these actions are based, should be made known to

the public as part of the decision process. The degree of detail and

type of information made available should be appropriate to the

potential radiation exposures involved. Information on risks should

encompass estimates of the risks of effects on health over time, and of

the uncertainties in such estimates. Information on policies should

include reference to this Federal radiation protection guidance for the

general public and other relevant Federal policies.

6. Assessments and records appropriate to the origin and magnitude

of expected doses and the exposed population should be performed and

maintained to demonstrate conformance with requirements which implement

these recommendations. The types and accuracy of methods and procedures

used in these assessments should be reviewed periodically to ensure

that they are appropriate and are being competently applied.

7. Exceptions to Recommendation 3 for planned exposure to radiation

should be made only for highly unusual circumstances, and only when the

Federal agency having jurisdiction has carefully considered the reasons

for making them in light of these recommendations. If Federal agencies

authorize any exception to these values, they should make it a matter

of public record.

Notes

The following notes are provided to clarify application of the

above recommendations:

1. Background radiation includes natural sources of background

radiation, such as cosmic radiation and radiation from naturally-

occurring radionuclides undisturbed by human activities, as well as

radiation from certain other sources of exposure beyond Federal

regulatory control, such as residual fallout from past nuclear

accidents and weapons tests.

2. People may, by technological means, enhance their exposure to

natural radiation sources that might otherwise be considered sources of

background radiation. Technologically-enhanced exposures to natural

radiation are usually controllable, in that they may be avoided or

reduced by taking reasonable actions. Unless specifically noted, these

recommendations apply to controllable technologically-enhanced exposure

to such natural radiation sources.

3. The admonition to maintain doses ``as low as reasonably

achievable'' includes consideration of economic and societal factors,

and applies to radiation exposure that may occur now or in the

foreseeable future. In making this judgment for doses to populations,

any incremental doses to individuals that are avoidable and which make

a significant contribution to collective dose should be considered.

4. Although indoor radon from proximate natural sources is

considered technologically-enhanced exposure to natural radiation,

Recommendations 3 and 4 of this guidance do not apply to such exposure.

Specific advice for protection against exposure to indoor radon is

provided in A Citizen's Guide To Radon (EPA document 402-K92-001 and

subsequent editions) and in other EPA technical publications.

5. The following values of the weighting factors wT may be

used to implement these recommendations:

Gonads........................................................... 0.25

Breasts.......................................................... 0.15

Red bone marrow.................................................. 0.12

Lungs............................................................ 0.12

Thyroid.......................................................... 0.03

Bone surfaces.................................................... 0.03

Remainder........................................................ 0.30

(``Remainder'' applies to the five other organs with the highest doses

(of the liver, kidneys, spleen, brain, thymus, adrenals, pancreas,

stomach, small intestine, and upper or lower large intestine, but

excluding skin, lens of eye, and extremities). The weighting factor for

each such organ is 0.06.)

6. The sum of weighted organ doses that comprises the effective

dose equivalent does not include an allowance for the induction of

fatal cancers in skin. In cases where dose to skin is large enough to

consider such effects, this may be done by adding to the effective dose

equivalent a terme that is the product of the skin dose equivalent

(averaged over the whole body) and a weighting factor wskin =

0.01.

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\e\Since the sum of the weighting factors is normalized to

unity, addition of a further factor would strictly require

adjustment of the other factors. In practice, the addition of this

small factor for skin does not warrant any change.

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7. The exposure-to-dose conversion factors tabulated in Federal

Guidance Report No. 11 (EPA-520/1-88-020), Federal Guidance Report No.

12 (EPA 402-R-93-081), and their subsequent editions should be used for

determining conformance to these recommendations. In addition,

dosimetric models and conventions and models for reference persons

specified by the International Commission on Radiological Protection

(ICRP) may be used. Under special circumstances, other factors may be

used when such factors are more appropriate on the basis of well-

established scientific evidence.

8. To ensure that specific sources or categories of sources,

including their installed control capability, are designed and operated

to achieve as low as reasonably achievable levels of exposure, a

variety of quantitative and qualitative analysis and decision methods

may be used to determine authorized limits. These, in addition to

considering radiation detriment and risk, and direct costs, may also

take into account societal and other economic factors. Statutory

requirements may impose additional constraints on the selection of

authorized limits.

[FR Doc. 94-31618 Filed 12-22-94; 8:45 am]

BILLING CODE 6560-50-P