\ UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
* WASHINGTON, B.C. 20460
Signed by Steve Luftig & Larry Weinstock on August 22, 1997
OFFICE OF
SOLID WASTE AND EMERGENCY
RESPONSE
OSWER No. 9200.4-18
MEMORANDUM
SUBJECT: Establishment of Cleanup Levels for CERCLA Sites with Radioactive
Contamination
FROM: Stephen D. Luftig, Director s/Stephen D. Luftig
Office of Emergency and Remedial Response
Larry Weinstock, Acting Director s/Larry Weinstock
Office of Radiation and Indoor Air
TO: Addressees
PURPOSE
This memorandum presents clarifying guidance for establishing protective
cleanup levels1 for radioactive contamination at Comprehensive Environmental
Response, Compensation, and Liability Act of 1980 (CERCLA) sites. The policies
stated in this memorandum are inclusive of all radioactive contaminants of concern at a
site including radon.2 The directive is limited to providing guidance regarding the
This directive provides guidance on cleanup levels expressed as a risk, exposure, or dose level and not as a soil
concentration level. The concentration level for various media, such as soil, that corresponds to a given risk level should be
determined on a site-specific basis, based on factors such as the assumed land use and the physical characteristics (e.g.,
important surface features, soils, geology, hydro geology, meteorology, and ecology) at the site. This guidance does not
alter the National Oil and Hazardous Substances Pollution Contingency Plan (NCP) expectations regarding treatment of
principal threat waste and the use of containment and institutional controls for low level threat waste.
Since radon is not covered in some Federal radiation regulations it is important to note that the cleanup guidance
clarifications in this memorandum include radon. Attachment A is a listing of standards for radionuclides (including
radon) that may be applicable or relevant and appropriate requirements (ARARs) for Superfund sites.
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protection of human health and does not address levels necessary to protect ecological
receptors.
This document provides guidance to EPA staff. It also provides guidance to the
public and to the regulated community on how EPA intends that the National Oil and
Hazardous Substances Pollution Contingency Plan (NCP) be implemented. The
guidance is designed to describe EPA's national policy on these issues. The document
does not, however, substitute for EPA's statutes or regulations, nor is it a regulation
itself. Thus, it cannot impose legally-binding requirements on EPA, States, or the
regulated community, and may not apply to a particular situation based upon the
circumstances. EPA may change this guidance in the future, as appropriate.
BACKGROUND
All remedial actions at CERCLA sites must be protective of human health and
the environment and comply with Applicable or Relevant and Appropriate Requirements
(ARARs) unless a waiver is justified. Cleanup levels for response actions under
CERCLA are developed based on site-specific risk assessments, ARARs, and/or to-be-
considered material3 (TBCs).
A listing is attached of radiation standards that are likely to be used as ARARs to
establish cleanup levels or to conduct remedial actions. Cleanup standards have been
under development by EPA under the Atomic Energy Act (AEA) and will be ARARs
under certain circumstances if issued.
ARARs are often the determining factor in establishing cleanup levels at
CERCLA sites. However, where ARARs are not available or are not sufficiently
protective, EPA generally sets site-specific remediation levels for: 1) carcinogens at a
level that represents an excess upper bound lifetime cancer risk to an individual of
between 10"4 to 10"6; and for 2) non-carcinogens such that the cumulative risks from
exposure will not result in adverse effects to human populations (including sensitive sub-
populations) that may be exposed during a lifetime or part of a lifetime, incorporating an
adequate margin of safety. (See 40 CFR 300.430(e)(2)(i)(A)(2).) Since all
radionuclides are carcinogens, this guidance addresses carcinogenic risk. If non-
carcinogenic risks are posed by specific radionuclides, those risks should be taken into
account in establishing cleanup levels or suitable remedial actions. The site-specific level
of cleanup is determined using the nine criteria specified in Section 300.430(e)(9)(iii) of
the NCP.
It is important to note that a new potential ARAR was recently promulgated :
To-be-considered material (TBCs) are non-promulgated advisories or guidance issued by Federal or State
governments that are not legally binding and do not have the status of potential ARARs. However, TBCs will be
considered along with ARARs as part of the site risk assessment and may be used in determining the necessary level of
cleanup for protection of health and the environment.
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NRC's Radiological Criteria for License Termination (See 62 FR 39058, July 21, 1997).
We expect that NRC's implementation of the rule for License Termination
(decommissioning rule) will result in cleanups within the Superfund risk range at the vast
majority of NRC sites. However, EPA has determined that the dose limits established in
this rule as promulgated generally will not provide a protective basis for establishing
preliminary remediation goals (PRGs) under CERCLA.4 The NRC rule set an allowable
cleanup level of 25 millirem per year (equivalent to approximately 5 x 10"4 increased
lifetime risk) as the primary standard with exemptions allowing dose limits of up to 100
millirem per year (equivalent to approximately 2 x 10"3 increased lifetime risk).
Accordingly, while the NRC rule standard must be met (or waived) at sites where it is
applicable or relevant and appropriate, cleanups at these sites will typically have to be
more stringent than required by the NRC dose limits in order to meet the CERCLA and
NCP requirement to be protective.5 Guidance that provides for cleanups outside the risk
range (in general, cleanup levels exceeding 15 millirem per year which equates to
approximately 3 x 10"4 increased lifetime risk) is similarly not protective under CERCLA
and generally should not be used to establish cleanup levels.
The lack of a protective comprehensive set of regulatory cleanup levels for
radiation, together with the possibility of confusion as to the status of other Federal
Agency regulations and guidance as ARARs or TBCs, may cause uncertainty as to the
cleanup levels deemed protective under CERCLA. Until a protective comprehensive
radiation cleanup rule is available, this guidance clarifies the Agency's position on
CERCLA cleanup levels for radiation.
OBJECTIVE
This guidance clarifies that cleanups of radionuclides are governed by the risk
range for all carcinogens established in the NCP when ARARs are not available or are
not sufficiently protective. This is to say, such cleanups should generally achieve risk
levels in the 10"4 to 10"6 range. EPA has a consistent methodology for assessing cancer
risks and determining PRGs at CERCLA sites no matter the type of contamination.6
Cancer risks for radionuclides should generally be estimated using the slope factor
approach identified in this methodology. Slope factors were developed by EPA for
more than 300 radionuclides in the Health Effects Assessment Summary Tables
See letter, Carol Browner, Administrator, EPA, to Shirley Jackson, Chairman, Nuclear Regulatory Commission,
February?, 1997.
See attachment B for a detailed discussion of the basis for the conclusion that the dose limits in the NRC rule are not
adequately protective.
U.S. EPA, "Risk Assessment Guidance for Superfund Volume I Human Health Evaluation Manual (Part A) Interim
Final," EPA//540/1 -89/002, December 1989. U.S. EPA, "Risk Assessment Guidance for Superfund: Volume I - Human
Health Evaluation Manual (Part B, Development of Risk-based Preliminary Remediation Goals", EPA/540/R-92/003,
December 1991.
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(HEAST).7 Cleanup levels for radioactive contamination at CERCLA sites should be
established as they would for any chemical that poses an unacceptable risk and the risks
should be characterized in standard Agency risk language consistent with CERCLA
guidance.
Historically, radiation exposure and cleanup levels have often been expressed in
units unique to radiation (e.g., millirem or picoCuries). It is important for the purposes
of clarity that a consistent set of existing risk-based units (i.e., # xlO"#) for cleanups
generally be used. This will also allow for ease and clarity of presenting cumulative risk
for all contaminants, an objective consistent with EPA's policy on risk characterization.8
Cancer risk from both radiological and non-radiological contaminants should be
summed to provide risk estimates for persons exposed to both types of carcinogenic
contaminants. Although these risks initially may be tabulated separately, risk estimates
contained in proposed and final site decision documents (e.g., proposed plans, Record of
Decisions (RODs), Action Memos, ROD Amendments, Explanation of Significant
Differences (ESDs)) should be summed to provide an estimate of the combined risk to
individuals presented by all carcinogenic contaminants.
IMPLEMENTATION
The approach in this guidance should be considered at current and future
CERCLA sites for which response decisions have not been made.
Overall Exposure Limit:
Cleanup should generally achieve a level of risk within the 10"4 to 10"6
carcinogenic risk range based on the reasonable maximum exposure for an individual.
The cleanup levels to be specified include exposures from all potential pathways, and
through all media (e.g., soil, ground water, surface water, sediment, air, structures,
biota). As noted in previous policy, "the upper boundary of the risk range is not a
discrete line at 1 x 10"4, although EPA generally uses 1 x 10"4 in making risk
management decisions. A specific risk estimate around 10"4 may be considered
acceptable if justified based on site-specific conditions".9
7U.S. EPA, "Health Effects Assessment Summary Tables FY-1995 Annual," EPA/540/R-95/036, May 1995; and U.S.
EPA, "Health Effects Assessment Summary Tables FY-1995 Supplement," EPA/540/R-95/142, Nov. 1995.
Q
For further discussion of EPA's policy, see memorandum from EPA Administrator Carol Browner entitled: "EPA
Risk Characterization Program," March 21, 1995.
Memo from Assistant Administrator Don Clay to the Regions; "Role of the Baseline Risk Assessment in Superfund
Remedy Selection Decisions'" OSWER Directive 9355.0-30; April 22, 1991.
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If a dose assessment is conducted at the site10 then 15 millirem per year
(mrem/yr) effective dose equivalent (EDE) should generally be the maximum dose limit
for humans. This level equates to approximately 3 x 10"4 increased lifetime risk and is
consistent with levels generally considered protective in other governmental actions,
particularly regulations and guidance developed by EPA in other radiation control
programs.11
Background Contamination:
Background radiation levels will generally be determined as background levels
are determined for other contaminants, on a site-specific basis. In some cases, the same
constituents are found in on-site samples as well as in background samples. The levels
of each constituent are compared to background to determine its impact, if any, on site-
related activities. Background is generally measured only for those radionuclides that are
contaminants of concern and is compared on a contaminant specific basis to cleanup
level. For example, background levels for radium-226 and radon-222 would generally
not be evaluated at a site if those radionuclides were not site-related contaminants.
In certain situations background levels of a site-related contaminant may equal
or exceed PRGs established for a site. In these situations background and site-related
levels of radiation will be addressed as they are for other contaminants at CERCLA
sites.12
Cleanup levels not based on ARARs should be expressed as risk, although levels may at the same time be expressed
in millirem.
Further discussion and analysis of the basis for this recommendation is contained in the materials in the docket for
the AEA standard under development by EPA, which is available at the following address: U.S. EPA, 401 M Street, S.W.,
Room M1500, Air Docket No. A-93-27, Washington D.C. 20460. The material is also available via computer modem
through the Cleanup Regulation Electronic Bulletin Board (800-700-7837 outside the Washington area and 703-790-0825
locally), or on-line through the Radiation Site Cleanup Regulation HomePage (http://www.epa.gov/radiation/cleanup/).
Cleanup levels based on some older ARARs that use a 25/75/25 mrem/yr standard (i.e., 25 mrem/yr to the whole body, 75
mrem/yr to the thyroid, and 25 mrem/yr to any other critical organ) may appear to permit greater risk than those based on
15 mrem EDE but on average correspond to approximately 10 mrem/yr EDE, using current risk methodologies. Similarly,
ARARs based on a 25/75 mrem/yr standard used as an ARAR (i.e., 25 mrem/yr to whole body and 75 mrem/yr to any
J \ ' J J J J
critical organ) would on average correspond to those cleanups based on 15 mrem/yr EDE. (See also "Comparison of
Critical Organ and EDE Radiation Dose Rate Limits for Situations Involving Contaminated Land;" Office of Radiation
and Indoor Air; April 1997.) See also Attachment B.
For further information regarding EPA's approach for addressing background at CERCLA sites see: National Oil
and Hazardous Substances Pollution Contingency Plan, 55 FR 8717-8718, March 8, 1990; U.S. EPA "Guidance on
Remedial Actions for Contaminated Ground Water at Superfund Sites," EPA/540/G-88/003, December 1988, pg. 4-9;
U.S. EPA "Soil Screening Guidance: User's Guide," EPA/540/R-96/018, April 1996, pg. 8; and U.S. EPA "Risk
Assessment Guidance for Superfund Volume I Human Health Evaluation Manual (Part A)," EPA/540/1-89/02, December
1989, pp. 4-5 to 4-10 and 5-18 to 5-19. It should be noted that certain ARARs specifically address how to factor
background into cleanup levels. For example, some radiation ARAR levels are established as increments above
background concentrations. (See attached chart for a listing of radiation standards that are likely to be used as ARARs.)
In these circumstances, rather then follow the general guidance cited above, background should be addressed in the manner
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Land Use and Institutional Controls:
The concentration levels for various media that correspond to the acceptable risk
level established for cleanup will depend in part on land use at the site. Land uses that
will be available following completion of a response action are determined as part of the
remedy selection process considering the reasonably anticipated land use or uses along
with other factors.13 Institutional controls (ICs) generally should be included as a
component of cleanup alternatives that would require restricted land use in order to
ensure the response will be protective over time. The institutional controls should
prevent an unanticipated change in land use that could result in unacceptable exposures
to residual contamination, or at a minimum, alert future users to the residual risks and
monitor for any changes in use.
Future Changes in Land Use:
Where waste is left on-site at levels that would require limited use and restricted
exposure to ensure protectiveness, EPA will conduct reviews at least once every five
years to monitor the site for any changes including changes in land use. Such reviews
should analyze the implementation and effectiveness of any ICs with the same degree of
care as other parts of the remedy. Should land use change in spite of land use
restrictions, it will be necessary to evaluate the implications of that change for the
selected remedy, and whether the remedy remains protective (e.g., a greater volume of
soil may need to be removed or managed to achieve an acceptable level of risk for a less
restrictive land use).
Ground Water Levels:
Consistent with CERCLA and the NCP, response actions for contaminated
ground water at radiation sites must attain (or waive as appropriate) the Maximum
Contaminant Levels (MCLs) or non-zero Maximum Contaminant Level Goals (MCLGs)
established under the Safe Drinking Water Act, where the MCLs or MCLGs are relevant
and appropriate for the site. This will typically be the case where ground waters are a
current or potential source of drinking water.14 The ARARs should generally be
attained throughout the plume (i.e., in the aquifer).
prescribed by the ARAR ARARs, such as 40 CFR 192, are available to establish cleanup levels for those naturally
occurring radionuclides that pose the most risk (such as radium-226 or Thorium in soil, and indoor radon) when those
radionuclides are site related contaminants.
In developing Land use assumptions, decision makers should consult the guidance provided in the memorandum
from Elliott Laws A.A., OSWER entitled: "Land Use in the CERCLA Remedy Selection Process" (OSWER Directive
No. 9355.7-04), May 25, 1995.
In making decisions on ground water protection, decision makers should consult the guidance provided in
"Presumptive Response Strategy and Ex-Situ Treatment Technologies for Contaminated Ground Water at CERCLA Sites"
(OSWER Directive No. 9355.7-04) October 1996.
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Modeling Assessment of Future Exposures:
Risk levels, ground water cleanup, and dose limits should be predicted using
appropriate models to examine the estimated future threats posed by residual radioactive
material following the completion of the response action.15 The modeling assessment
should: (1) assume that the current physical characteristics (e.g., important surface
features, soils, geology, hydrogeology, meteorology, and ecology) will continue to exist
at the site; (2) take into account for each particular radionuclide that is a site-related
contaminant, the following factors:
• radioactive decay and the ingrowth of radioactive decay products when assessing
risk levels;
• the year of peak concentration in the ground water when assessing protection
(e.g., remediating previous contamination and preventing future contamination)
of ground water, and;
the year of peak dose when assessing dose limits; and,
(3) model the expected movement of radioactive material at the site both within media
(i.e., soil, ground water, surface water, sediment, structures, air, biota) and to other
media.
FURTHER INFORMATION
The subject matter specialists for this directive are Jeffrey Phillips of OERR and
John Karhnak of ORIA. General questions about this directive, should be directed to
1-800-424-9346.
Attachments
Addressees
National Superfund Policy Managers
Superfund Branch Chiefs (Regions I-X)
Superfund Branch Chiefs, Office of Regional Counsel (Regions I-X)
Radiation Program Managers (Regions I, IV, V, VI, VII, X)
Radiation Branch Chief (Region II)
Residential Domain Section Chief (Region III)
Radiation and Indoor Air Program Branch Chief (Region VIII)
Radiation and Indoor Office Director (Region IX)
Federal Facilities Leadership Council
OERR Center Directors
For further information regarding the basis for this recommendation, see U.S. EPA, "Risk Assessment Guidance for
Superfund Volume I Human Health Evaluation Manual (Part A) Interim Final," EPA//540/1 -89/002, December 1989, pp.
10-22 and 10-24.
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OSWER Directive 9200.4-18
Attachment A
Likely Federal Radiation Applicable or Relevant and Appropriate Requirements
(ARARs)
The attached draft table of Federal standards is a listing of Federal radiation regulations that may be "Applicable or Relevant and
Appropriate Requirements" (ARARs) for Superfund response actions. This list is not a comprehensive list of Federal radiation
standards. It must also be cautioned that the selection of ARARs is site-specific and those site-specific determinations may differ from
the attached analysis for some of the following ARARs.
Likely Federal Radiation (AEA, UMTRCA, CAA, CWA, SDWA) ARARs
Standard
Citation
When is standard
Applicable
(Conduct/Operation
or Level of
Cleanup1)
When is standard
potentially a Relevant
and Appropriate
Requirement
Maximum contaminant levels (MCLs). Drinking
water regulations designed to protect human
health from the potential adverse effects of
drinking water contaminants.
40 CFR 141
Rarely: At the tap where
water will be provided
directly to 25 or more
people or will be supplied
to 15 or more service
connections.
Where ground or surface water
is considered a potential or
current source of drinking
water
Concentration limits for liquid effluents from
facilities that extract and process uranium,
radium, and vanadium ores.
40 CFR 440
Subpart C
Very Unlikely: Applies to
surface water discharges
from certain kinds of
mines and mills
Discharges to surface waters
of some kinds of radioactive
waste.
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Likely Federal Radiation (AEA, UMTRCA, CAA, CWA, SDWA) ARARs
Standard
Citation
When is standard
Applicable
(Conduct/Operation
or Level of
Cleanup1)
When is standard
potentially a Relevant
and Appropriate
Requirement
Federal Water Quality Criteria (FWQC) and State
Water Quality Standards (WQS).
Criteria/standards for protection of aquatic life
and/or human health depending upon the
designated water use.
Water Quality
Criteria; Report
of the National
Technical
Advisory
Committee to the
Secretary of the
Interior; April 1,
1968.
Discharge from a
CERCLA site to surface
water. (C/O)
Restoration of contaminated
surface water. (LC)
Concentration limits for cleanup of radium-226,
radium-228, and thorium in soil at inactive
uranium processing sites designated for remedial
action.
40CFR
192.12(a),
192.32(b)(2), and
192.41
Never. Standards are
applicable only to
UMTRCA sites that are
exempt from CERCLA
Sites with soil contaminated
with radium-226, radium-228,
and/or thorium
2For further information, see OSWER directive entitled "Use of Soil Cleanup Criteria in Subpart B of 40 CFR Part 192 as
Remediation Goals for CERCLA sites."
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Likely Federal Radiation (AEA, UMTRCA, CAA, CWA, SDWA) ARARs
Standard
Citation
When is standard
Applicable
(Conduct/Operation
or Level of
Cleanup1)
When is standard
potentially a Relevant
and Appropriate
Requirement
Combined exposure limits for cleanup of radon
decay products in buildings at inactive uranium
processing sites designated for remedial action
40CFR
192.12(b)(l)and
192.41(b)
Never: Standards are
applicable only to
UMTRCA sites that are
exempt from CERCLA
Sites with radioactive
contamination that is currently,
or may potentially, result in
radon that is caused by site
related contamination
migrating from the soil into
buildings
Concentration limits for cleanup of gamma
radiation in buildings at inactive uranium
processing sites designated for remedial action
40CFR
192.12(b)(2)
Never. Standards are
applicable only to
UMTRCA sites that are
exempt from CERCLA
Sites with radioactive
contamination that is currently,
or may potentially, emit
gamma radiation
Design requirements for remedial actions that
involve disposal for controlling combined releases
of radon-220 and radon-222 to the atmosphere at
inactive uranium processing sites designated for
remedial action
40 CFR 192.02
Never: Standards are
applicable only to
UMTRCA sites that are
exempt from CERCLA
Sites with radon-220 or radon-
222 as contaminants which will
be disposed of on-site.
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Likely Federal Radiation (AEA, UMTRCA, CAA, CWA, SDWA) ARARs
Standard
Citation
When is standard
Applicable
(Conduct/Operation
or Level of
Cleanup1)
When is standard
potentially a Relevant
and Appropriate
Requirement
Performance objectives for the land disposal of
low level radioactive waste (LLW).
10 CFR 61.41
Unlikely: Existing
licensed LLW disposal
sites at the time of license
renewal. (LC)
Unlikely that this would
occur.
Previously closed sites
containing LLW if the waste
will be permanently left on site.
National Emission Standards for Hazardous Air
Pollutants (NESHAPs) under the Clean Air Act,
that apply to radionuclides.
40 CFR 61
Subparts H and I
Airborne emissions during
the cleanup of Federal
Facilities and licensed
NRC facilities. (CO)
Cleanup of other sites with
radioactive contamination.
Radiological criteria for license termination.
10 CFR 20
Subpart E
Existing licensed sites at
the time of license
termination. (LC)
Previously closed sites.
1.Conduct/operation (C/O) refers to those standards which are typically ARARs for the conduct or operation of the remedial action.
Level of Cleanup (L/C) refers to those standards which are typically ARARs for determining the final level of cleanup.
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August 20, 1997
OSWER Directive 9200.4-18
Attachment B
Analysis of what Radiation Dose Limit
is Protective of Human Health
at CERCLA Sites
(Including Review of Dose Limits in
NRC Decommissioning Rule)
Introduction
The Nuclear Regulatory Commission ("NRC") has finalized a rule titled
"Radiological Criteria for License Termination" (see 62 FR 39058, July 21, 1997). EPA
has determined that the dose limits established in this rule generally will not provide a
protective basis for establishing preliminary remediation goals ("PRGs")under the
Comprehensive Environmental Response, Compensation and Liability Act ("CERCLA").1
The NRC rule sets an allowable cleanup level of 25 millirem per year effective dose
equivalent (EDE) (equivalent to approximately 5 x 10"4 lifetime cancer risk) as the primary
standard with exemptions allowing cleanup levels of up to 100 millirem per year (mrem/yr)
EDE (equivalent to approximately 2 x 10"3 lifetime risk).2 While the NRC standards must
be met (or waived) at sites where it is applicable or relevant and appropriate, cleanups at
these sites will typically have to be more protective than required by the NRC rule dose
limits in order to meet the requirement to be protective established in CERCLA and the
1990 revisions to the National Oil and Hazardous Substances Pollution Contingency Plan
("NCP").3
Protectiveness for carcinogens under CERCLA is generally determined with
reference to a cancer risk range of 10"4 to 10"6 deemed acceptable by EPA. Consistent
with this risk range, EPA has considered cancer risk from radiation in a number of
different contexts, and has consistently concluded that levels of 15 mrem/yr EDE (which
See letter, Carol Browner, Administrator, EPA, to Shirley Jackson, Chairman, Nuclear Regulatory Commission,
February?, 1997.
Throughout this analysis risk estimates for dose levels were derived using a risk assessment methodology consistent
with CERCLA guidance for assessing risks.
Similarly, guidance that provides for radiation cleanups outside the risk range is generally not protective and should
not be used to establish preliminary remediation goals .
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August 20, 1997
equate to approximately a 3 x 10"4 cancer risk) or less are protective and achievable.4
EPA has explicitly rejected levels above 15 mrem/yr EDE as being not sufficiently
protective.
The dose levels established in the NRC Decommissioning rule, however, are not
based on this risk range or on an analysis of other achievable protective cleanup levels
used for radiation and other carcinogenic standards. Rather, they are based on a different
framework for risk management recommended by the International Commission on
Radiation Protection (ICRP) and the National Council on Radiation Protection and
Measurements (NCRP). NRC's application of this framework starts with the premise that
exposure to radiation from all man-made sources, excluding medical and natural
background exposures, of up to 100 mrem/yr., which equates to a cancer risk of 2 x 10"3,
is acceptable. Based on that premise, it concludes that exposure from decommissioned
facilities of 25 mrem/yr, which equates to a cancer risk of approximately 5 x 10"4, is
acceptable, and allows the granting of exceptions in certain instances permitting exposure
up to the full dosage of 100 mrem/yr from these facilities. EPA has carefully reviewed the
basis for the NRC dose levels and does not believe they are generally protective within the
framework of CERCLA and the NCP. Simply put, NRC has provided, and EPA is aware
of, no technical, policy, or legal rationale for treating radiation risks differently from other
risks addressed under CERCLA and for allowing radiation risks so far beyond the bounds
of the CERCLA risk range.
1. Rationale for 15 mrem/yr as Minimally Acceptable Dose Limit
To determine an acceptable residual level of risk from residual radioactive
materials following a response action that would be protective of human health, EPA
examined the precedents established by EPA for acceptable exposures to radiation in
regulations and site-specific cleanup decisions in light of the CERCLA risk range for
carcinogens. EPA's conclusion is that to be considered protective under CERCLA,
remedial actions should generally attain dose levels of no more than 15 mrem/yr EDE for
those sites at which a dose assessment is conducted. This dose level corresponds to an
excess lifetime cancer risk of approximately 3 x 10"4.
1.1 The CERCLA risk range
Under CERCLA, all remedies are required to attain cleanup levels that "at a
minimum. . . assure protection of human health and the environment." CERCLA
It should be noted that 15 mrem/yr is a dose level, not a media remediation level. Accordingly, this level could be
achieved at CERCLA sites through appropriate site-specific combinations of active remediation and land-use restrictions to
ensure no unacceptable exposures.
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August 20, 1997
§121(d)(l). The NCP provides that, for carcinogens, preliminary remediation goals
should generally be set at levels that represent an upper-bound lifetime cancer risk to an
individual of between 10'4 and 10'6. 40 CFR § 300.430(e)(2)(I)(A)(l). This regulatory
level was set based on EPA's conclusion that the CERCLA protectiveness mandate is
complied with "when the amount of exposure is reduced so that the risk posed by
contaminants is very small, i.e., at an acceptable level. EPA's risk range of 10"4 to 10"6
represents EPA's opinion on what are generally acceptable levels." 55 Fed. Reg. at 8716
(March 8, 1990). EPA's adoption of this risk range was sustained in judicial review of the
NCP. State of Ohio v. EPA. 997F.2d 1520, 1533 (D.C. Cir. 1993).
Under appropriate circumstances, risks of greater than 1 x 10"4 may be acceptable.
CERCLA guidance states that "the upper boundary of the risk range is not a discrete line
at 1 x 10"4, although EPA generally uses 1 x 10"4 in making risk management decisions. A
specific risk estimate around 10"4 may be considered acceptable if justified based on site-
specific conditions."5 Other EPA regulatory programs have developed a similar approach
to determining acceptable levels of cancer risk. For example, in a Clean Air Act
rulemaking establishing NESHAPs forNRC licensees, Department of Energy facilities,
and many other kinds of sites, EPA concluded that a risk level of "3 x 10"4 is essentially
equivalent to the presumptively safe level of 1 x 10"4." 54 Fed. Reg. at 51677 and 51682
(December 15, 1989). EPA explicitly rejected a risk level of 5.7 x 10"4 as not being
equivalent to the presumptively safe level of 1 x 10"4 (in the case of elemental phosphorus
plants) in this rulemaking. 54 Fed. Reg. at 51670.
1.2 Prior rulemaking decisions
EPA has examined the protectiveness of various radiation levels on a number of
occasions. In each case, EPA's determination of what constitutes an adequate level of
protection was reached in a manner consistent with EPA's regulation of other
carcinogens. The conclusions from these efforts support the determination that 15
mrem/yr EDE should generally be the maximum dose level allowed at CERCLA sites. For
example, EPA's Environmental Radiation Protection Standards for Management and
Disposal of Spent Nuclear Fuel, High-Level and Transuranic Radioactive Wastes ("High-
Level Waste Rule," 40 CFR Part 191) sets a dose limit of 15 mrem/yr EDE for all
pathways.
In addition, EPA set an effective dose equivalent of 10 mrem/yr EDE (excluding
radon-222) for air emissions of radionuclides from federal facilities, NRC licensees, and
uranium fuel cycle facilities under the National Emissions Standards for Hazardous Air
"Role of the Baseline Risk Assessment in Superfund Remedy Selection Decisions" from EPA Assistant Administrator Don
R. Clay, April 22, 1991.
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August 20, 1997
Pollutants (NESHAP, 40 CFR Part 61). This lower limit included all air pathways, but
excluded releases to surface and ground waters.
Not all EPA rules apply the current dose methodology of effective dose equivalent
(EDE). A dose limit of 15 mrem/yr EDE is also consistent with the dose levels allowed
under older multi-media standards that were based on the critical organ approach to dose
limitation. Critical organ standards developed by EPA and NRC consist of a combination
of whole body and critical organ dose limits. Three of these critical organ standards
(EPA's uranium fuel cycle rule, 40 CFR 190.10(a), developed for NRC licensees; NRC's
low level waste rule, 10 CFR 61.41; and EPA's management and storage of high level
waste by NRC and agreement states rule, 40 CFR 191.03(a)), referred to here as
'25/75/25 mrem/yr' dose limits, are expressed as 25 mrem/yr to the whole body, 75
mrem/yr to the thyroid, and 25 mrem/yr to any critical organ other than the thyroid. One
standard (EPA's management and storage of high level waste by DOE rule, 40 CFR
191.03(b)), referred to here as a "25/75 mrem/yr" dose limit, is expressed as 25 mrem/yr
to the whole body and 75 mrem/yr to any critical organ (including the thyroid). To
compare the dose level allowed under standards expressed in terms of EDE with the dose
levels allowed under the critical organ approach to dose limitation, EPA has analyzed the
estimated effective dose equivalent levels that would result if sites were cleaned up to the
numerical dose limits used in these standards.6 The analysis indicates that if sites were
cleaned up under a 25/75/25 mrem/yr dose limit, the residual contamination would
correspond to approximately 10 mrem/yr EDE. For sites cleaned up under a 25/75
mrem/yr dose limit, the residual contamination would correspond to approximately 15
mrem/yr EDE. These findings are similar to those mentioned in the preamble to the high-
level waste rule (40 CFR Part 191; December 20, 1993; 58 FR 66402). In that
rulemaking, EPA noted that the dose limit of 25 mrem/yr to the whole body or 75
mrem/yr to any critical organ, which was used in a previous high-level waste rule
(September 19, 1985; 50 FR 38066) corresponds to the same level of risk as that
associated with a 15 mrem/yr EDE. A cleanup level of 15 mrem/yr EDE is thus generally
consistent with all of these other standards, although there are minor differences.
Finally, standards for the cleanup of certain radioactively contaminated sites have
been issued under the Uranium Mill Tailings Radiation Control Act (UMTRCA), P.L. 95-
604. Those standards are codified at 40 CFR Part 192. Among other provisions, the
UMTRCA standards limit the concentration of radium-226, radium-228, thorium-230 and
thorium-232, within 15 centimeters (cm) of the surface to no more than 5 picoCuries per
gram (pCi/g) over background. They also limit the concentration of these radionuclides
below the surface to no more than 15 pCi/g over background. Since these standards were
"Comparison of Critical Organ and EDE Radiation Dose Rate Limits for Situations Involving Contaminated Land"
Office of Radiation and Indoor Air; April 1997.
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August 20, 1997
developed for the specific conditions found at the mill sites to which they apply (for
example, all mill sites are required by law to remain in federal control), correlating these
concentrations to dose requires a site-specific determination considering both the
distribution and nature of contaminants at the site and the selected land use. Therefore,
those standards are less relevant for determining if 15 mrem/yr EDE is consistent.
However, analysis indicates that the cleanup of UMTRCA sites is consistent with the
minimally acceptable dose limit of 15 mrem/yr EDE under a residential exposure scenario
for radium-226, radium-228, and thorium-232, and is much more stringent for thorium-
230.7 For land uses other than residential (e.g., commercial/industrial, recreational) the
UMTRCA cleanup standards are more stringent for all four radionuclides.8
1.3 Site-Specific Decisions
EPA has examined the cleanup decisions made under Superfund to address sites
contaminated with radioactive wastes. Many of these cleanup actions used the UMTRCA
cleanup standard (40 CFR Part 192) as an ARAR. Some of the sites used State
regulations as ARARs. For a number of major DOE cleanup actions such as those at the
Hanford reservation and Rocky Flats, a 15 mrem/yr EDE cleanup level has been decided
upon or proposed. In other cases of CERCLA radiation cleanup actions that are not
based on ARARs, cleanup levels between 1 x 10"5 and 1 x 10"6 have been selected
(Bomark, NJ; Fernald, OH; Charleston Naval Shipyard, SC; and Mare Island Naval
Shipyard, CA). Overall EPA finds that a 15 mrem/yr EDE level (with a risk of 3 x 10"4) is
at the upper end of remediation levels that have generally been selected at radioactively
contaminated CERCLA sites.
2.0 Dose Limits in NRC's Rule are not Protective
EPA reviewed the dose limits that are contained in NRC's Radiological Criteria for
License Termination (see 62 FR 39058, July 21, 1997). The NRC rule allows a cleanup
level of 25 mrem/yr EDE (equivalent to approximately 5 x 10"4 lifetime risk) with
exemptions allowing cleanup levels of up to 100 mrem/yr EDE (equivalent to
approximately 2 x 10"3 lifetime risk). These limits are beyond the upper bound of the risk
Reassessment ofRadium andThorium Soil Concentrations and'AnnualDoseRates . Office of Radiation and Indoor
Air, July 22, 1996.
Q
A level of 15 mrem/yr is also supported by EPA's draft Federal Radiation Protection Guidance for Exposure of the
General Public (59 FR 66414, December 23, 1994). The draft guidance recommends that the maximum dose to individuals
from specific sources or categories of sources be established as small fractions of a 100 mrem/yr upper bound on doses from
all current and potential future sources combined, and cites the regulations that are discussed in Section 1.2 of this paper as
appropriate implementation of this recommendation. All of the regulatory examples cited support the selection of cleanup
levels at 15 mrem/yr or less. However, because this guidance is in draft form and is subject to continued review within EPA
prior to finalization, it should not be used as a basis for establishing acceptable cleanup levels.
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August 20, 1997
range generally considered protective under CERCLA. In addition, they present risks that
are higher than levels EPA has found to be protective for carcinogens in general and for
radiation, in particular, in other contexts. EPA has no technical or policy basis to
conclude that these levels are protective under CERCLA.
The risk levels corresponding to the 25 to 100 mrem/yr EDE range allowed by the
NRC rule (5 x 10"4to 2 x 10"3) are unacceptably high relative to 1 x 10"4, which is the risk
level generally used as the upper boundary of the CERCLA risk range for making risk
management decisions at CERCLA sites. This determination is consistent with EPA's
explicit rejection of a risk level of 5.7 x 10"4 for elemental phosphorus plants in the
preamble for a NESHAP rulemaking (54 FR 51670). In the same preamble, EPA stated
that a risk level of "3 x 10"4 is essentially equivalent to the presumptively safe level of 1 x
10'4" (54 FR 51677). It was during this same NESHAP rulemaking that NCRP first
recommended to EPA its regulatory scheme (a dose limit of 25 mrem/yr EDE for a single
source that if met would not require analyzing other sources, otherwise a dose limit of 100
mrem/yr EDE from all sources combined) that NRC cites as a source for the regulatory
approach taken in its decommissioning rule.9 EPA rejected NCRP's recommended
regulatory scheme, and promulgated dose limits of no more than 10 mrem/yr EDE in its
NESHAP rulemaking for radionuclides, while concluding that "individual dose levels
greater than 10 mrem/y ede are inconsistent with the requirements of section 112" of the
Clean Air Act. 54 Fed. Reg. at 51686.
The documentation and analysis supporting the NRC rule dose levels provide no
basis for such a significant departure from the CERCLA risk range. Indeed, as discussed
above, EPA's past analyses and experience have demonstrated that exposures of 15
mrem/yr EDE or less are attainable and that such a departure is unwarranted. A dose limit
of 25 mrem/yr EDE represents almost a doubling of the allowable risk from previous
radiation rulemakings; the risk represented by a dose limit of 100 mrem/yr EDE is seven
times as high as previously allowed. As note in Section 1.2, a dose limit of 25 mrem/yr
effective dose equivalent is inconsistent with the dose levels allowed under older standards
using a previous dose methodology (multi-media standards that were based on the critical
organ approach to dose limitation). If these older dose standards were to be applied to the
cleanup of contaminated sites, the average dose level would correspond to approximately
10 or 15 mrem/yr EDE on average.10 Also, analysis indicates that the cleanup of
UMTRCA sites using the 5 pCi/g and 15 pCi/g soil standards under 40 CFR 192 is
consistent with an upper bound of 15 mrem/yr EDE under a rural residential exposure
9"Control of Air Emissions of Radionuclides" NCRP Position Statement No. 6. The report cited by NRC, NCRP No.
116, merely references this previous NCRP position statement.
"Comparison of Critical Organ andE
Office of Radiation and Indoor Air; April 1997.
"Comparison of Critical Organ and EDE Radiation Dose Rate Limits for Situations Involving Contaminated Land"
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August 20, 1997
scenario for radium-226, radium-228, and thorium-232, and is much more stringent for
thorium-230.11 For land uses other than residential (e.g., commercial/industrial,
recreational) the UMTRCA cleanup standards are more stringent for all four
radionuclides.
Reassessmen t of Radium and Thorium Soil Concentrations and Annual Dose Rates . Office of Radiation and
Indoor Air, July 22, 1996.
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, B.C. 20460
Signed by Timothy Fields on August 22, 1997
OFFICE OF
SOLID WASTE AND EMERGENCY
RESPONSE
OSWER No. 9200.4-23
MEMORANDUM
SUBJECT: Clarification of the Role of Applicable, or Relevant and Appropriate
Requirements in Establishing Preliminary Remediation Goals under
CERCLA
FROM: Timothy J. Fields, Jr., Acting s/Timothy Fields, Jr.
Assistant Administrator
TO: Addressees
PURPOSE
This memorandum clarifies the relationship between the two key remedy selection
mandates of the Comprehensive Environmental Response, Compensation and Liability Act
(CERCLA) as amended by the Superfund Amendments and Reauthorization Act of 1986
(SARA): 1) the requirement to protect human health and the environment; and 2) the
requirement to attain, or waive if justified based on site-specific circumstances, applicable
or relevant and appropriate requirements (ARARs). Specifically, this memorandum
clarifies that, in rare instances, the Agency may establish preliminary remediation goals
(PRGs) at levels more protective than required by ARARs, even at sites that do not
involve multiple contaminants or pathways of exposure.
This document provides guidance to Regional staff, in dealing with the public and
the regulated community, regarding how EPA intends to implement the National Oil and
Hazardous Substances Pollution Contingency Plan (NCP). It describes national policy.
This document is not a substitute for EPA's statutes or regulations, nor is it a regulation
itself. Thus, it cannot impose legally-binding requirements on EPA, States, or the
regulated community, and may not apply to a particular situation based upon the
circumstances.
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BACKGROUND
In administering the CERCLA program since the promulgation of the 1990
revisions to the NCP, questions have periodically arisen over the relationship between the
statutory mandates to: 1) protect human health and the environment; and, 2) attain, or
waive if justified based on site-specific circumstances, ARARs. Specifically, questions
have arisen over the circumstances under which it is appropriate to establish PRGs that are
more protective than ARARs. It has been EPA's policy that "compliance with a chemical-
specific ARAR generally will be considered protective even if it is outside the [cancer] risk
range (unless there are extenuating circumstances such as exposures to multiple
contaminants or pathways of exposure)."1
FURTHER EXPLANATION OF POLICY
It remains EPA's policy that ARARs will generally be considered protective absent
multiple contaminants or pathways of exposure. However, this Directive clarifies that, in
rare situations, EPA Regional offices should establish PRGs at levels more protective than
required by a given ARAR, even absent multiple pathways or contaminants, where
application of the ARAR would not be protective of human health or the environment.
This judgment should be made based on a review of the level of risk associated with
application of the ARAR; the soundness of the technical basis for the ARAR; and other
factors relating to the ARAR or to its application at an individual site.
This balanced approach most fully implements the requirements of the NCP and
the CERCLA. On one hand, it was clearly EPA's intention in promulgating the NCP that
PRGs would generally be based on ARARs in the absence of multiple contaminants or
pathways. (See 40 CFR 300.430(e)(2)(I)(D); 55 Fed. Reg. at 8712.) This approach is
sound; the protectiveness of health-based regulatory levels should not routinely be re-
evaluated in individual CERCLA remedy selection decisions.
On the other hand, ARARs cannot be an absolute upper bound on cleanup levels in
every case in the absence of multiple pathways or contaminants. CERCLA and the NCP
establish separate requirements to be protective and meet ARARs. (CERCLA §
121(d)(l), (2); 40 CFR § 300.430(f)(l)(I)(A).) Indeed, protecting human health and the
environment is the paramount objective of the Superfund program. (See 55 Fed. Reg.
OSWER Directive 9355.0-30, "Role of the Baseline Risk Assessment in Superfund Remedy Selection
Decisions" (April 22, 1991). This policy is consistent with the NCP. ( See 40 CFR 300.430(e)(2)(I)(D) (authorizing
consideration of the cancer risk range where attainment of ARARs will result in cumulative cancer risk of greater than 10
due to multiple pathways or contaminants). See also 1990 NCP Preamble, 55 Fed. Reg. at 8712 ("[w]hen health-based
ARARs are not available or are not sufficiently protective due to multiple exposures or multiple contaminants, EPA sets
remediation goals" based on site-specific risk-based factors, such as the cancer risk range).)
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8700 (the NCP remedy selection process "is founded on CERCLA's overarching mandate
to protect human health and the environment").) Furthermore, CERCLA requires that
remedial actions attain ARARs "at a minimum," clearly contemplating that remedial
actions may be more protective than required by ARARs when circumstances so require.
(CERCLA § 121(d)(2)(A).)
EPA's policy of generally establishing PRGs based on ARARs, in the absence of
multiple pathways or contaminants, is based on the assumption that individual ARARs will
be protective. For example, the NCP expressly authorizes consideration of the cancer risk
range in setting PRGs where attainment of ARARs would result in a cumulative risk in
excess of 10'4 due to multiple contaminants or pathways. (40 CFR 300.430(e)(2)(I)(D).)
The assumption underlying this provision is plainly that individual ARARs would achieve a
risk of 10"4 or less. Similarly, the NCP preamble explains that EPA will modify PRGs to
be protective where cumulative risks "make ARARs nonprotective" (55 Fed. Reg. at
8713); again, the assumption is that individual ARARs would be protective absent these
cumulative risks. In cases where, based on available information, this assumption is not
accurate, PRGs should be set at levels more protective than required by the ARAR in
order to ensure protection of human health and the environment.
IMPLEMENTATION
In the rare circumstances where, based on available information, application of an
ARAR would not be protective of human health or the environment, EPA should establish
PRGs at levels that are more protective than required by the ARAR even absent multiple
pathways or contaminants. As noted above, in deciding whether a PRG should be
established at a level more protective than required by an ARAR, consideration should be
given to the level of risk associated with application of the ARAR; the soundness of the
technical basis for the ARAR; and other factors relating to the ARAR or to its application
at an individual site.
Before making a site-specific determination that an ARAR at a given site is not
protective of human health and the environment and should not be used as the basis for
establishing PRGs, the site decision maker should consult with Headquarters, unless a
prior determination has been made by Headquarters that a particular ARAR should not
generally be used to establish PRGs at CERCLA sites.2 The subject matter specialist for
this guidance is Robin Anderson of OERR and Brian Grant of OGC. General questions
about this guidance should be directed to 1-800-424-9346.
Addressees
National Superfund Policy Managers
For an example of a Headquarters determination that the numerical limits established by a particular ARAR
should not generally be used as the basis to establish PRGs at CERCLA sites, see the memorandum from Stephen D.
Luftig titled: "Establishment of cleanup levels for CERCLA sites with radioactive contamination" (OSWER Directive
9200.4-18), August 1997, p. 3.
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Superfund Branch Chiefs (Regions I-X)
Superfund Branch Chiefs, Office of Regional Counsel (Regions I-X)
Radiation Program Managers (Regions I, IV, V, VI, VII, X)
Radiation Branch Chief (Region II)
Residential Domain Section Chief (Region III)
Radiation and Indoor Air Program Branch Chief (Region VIII)
Radiation and Indoor Office Director (Region IX)
Federal Facilities Leadership Council
OERR Center Directors
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