[Federal Register Volume 86, Number 156 (Tuesday, August 17, 2021)]
[Proposed Rules]
[Pages 45923-45936]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-17475]
========================================================================
Proposed Rules
Federal Register
________________________________________________________________________
This section of the FEDERAL REGISTER contains notices to the public of
the proposed issuance of rules and regulations. The purpose of these
notices is to give interested persons an opportunity to participate in
the rule making prior to the adoption of the final rules.
========================================================================
Federal Register / Vol. 86, No. 156 / Tuesday, August 17, 2021 /
Proposed Rules
[[Page 45923]]
NUCLEAR REGULATORY COMMISSION
10 CFR Part 20
[Docket No. PRM-20-28, PRM-20-29, and PRM-20-30; NRC-2015-0057]
Linear No-Threshold Model and Standards for Protection Against
Radiation
AGENCY: Nuclear Regulatory Commission.
ACTION: Petition for rulemaking; denial.
-----------------------------------------------------------------------
SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) is denying three
petitions for rulemaking (PRMs), submitted by Dr. Carol S. Marcus, Mr.
Mark L. Miller, Certified Health Physicist, and Dr. Mohan Doss, et al.
(collectively, the petitioners) in correspondence dated February 9,
2015, February 13, 2015, and February 24, 2015, respectively. The
petitioners request that the NRC amend its regulations based on what
they assert is new science and evidence that contradicts the linear no-
threshold (LNT) dose-effect model that serves as the basis for the
NRC's radiation protection regulations. The NRC docketed these
petitions on February 20, 2015, February 27, 2015, and March 16, 2015,
and assigned them Docket Numbers PRM-20-28, PRM-20-29, and PRM-20-30,
respectively. The NRC is denying the three petitions because they fail
to present an adequate basis supporting the request to discontinue use
of the LNT model. The NRC has determined that the LNT model continues
to provide a sound regulatory basis for minimizing the risk of
unnecessary radiation exposure to both members of the public and
radiation workers. Therefore, the NRC will maintain the current dose
limit requirements contained in its regulations.
DATES: The dockets for PRM-20-28, PRM-20-29, and PRM-20-30 are closed
on August 17, 2021.
ADDRESSES: Please refer to Docket ID NRC-2015-0057 when contacting the
NRC about the availability of information for this action. You may
obtain publicly-available information related to this action by any of
the following methods:
Federal Rulemaking Website: Go to https://www.regulations.gov and search for Docket ID: NRC-2015-0057. Address
questions about NRC dockets to Dawn Forder, telephone: 301-415-3407,
email: [email protected]. For technical questions, contact individual
listed in the FOR FURTHER INFORMATION CONTACT section of this document.
NRC's Agencywide Documents Access and Management System
(ADAMS): You may obtain publicly-available documents online in the
ADAMS Public Documents collection at https://www.nrc.gov/reading-rm/adams.html. To begin the search, select ``ADAMS Public Documents'' and
then select ``Begin Web-based ADAMS Search.'' For problems with ADAMS,
please contact the NRC's Public Document Room (PDR) reference staff at
1-800-397-4209, 301-415-4737, or by email to [email protected]. For
the convenience of the reader, a list of materials referenced in this
document are provided in Section V, ``Availability of Documents.''
Attention: The PDR, where you may examine and order copies
of public documents, is currently closed. You may submit your request
to the PDR via email at [email protected] or call 1-800-397-4209
between 8:00 a.m. and 4:00 p.m. (EST), Monday through Friday, except
Federal holidays.
FOR FURTHER INFORMATION CONTACT: Vanessa Cox, Office of Nuclear
Material Safety and Safeguards, telephone: 301-415-8342; email:
[email protected]; U.S. Nuclear Regulatory Commission, Washington, DC
20555-0001.
SUPPLEMENTARY INFORMATION:
I. The Petitions
Section 2.802 of title 10 of the Code of Federal Regulations (10
CFR), ``Petition for rulemaking--requirements for filing,'' provides an
opportunity for any interested person to petition the Commission to
issue, amend, or rescind any regulation in 10 CFR chapter I. By
correspondence dated February 9, 2015, February 13, 2015, and February
24, 2015, respectively, the NRC received three similar petitions from
Dr. Carol S. Marcus, Mark L. Miller, CHP, and Mohan Doss, Ph.D., et
al.\1\ The NRC published a notice of docketing for the three petitions
in the Federal Register on June 23, 2015 (80 FR 35870), and requested
public comment. The public comment period was initially set to close on
September 8, 2015, but was extended to November 19, 2015.\2\
---------------------------------------------------------------------------
\1\ Dr. Doss was the first of several signatories on the
February 24, 2015, correspondence. The correspondence identified the
signatories as members or associate members of Scientists for
Accurate Radiation Information (SARI). There is no indication in the
February 24, 2015, correspondence that SARI, as an organization,
formally endorsed the petition from Dr. Doss, et al.
\2\ 80 FR 50804-05; August 21, 2015.
---------------------------------------------------------------------------
The petitioners request that the NRC amend 10 CFR part 20,
``Standards for Protection against Radiation,'' to discontinue use of
the LNT model as the primary scientific basis for the agency's
radiation protection standards. The petitioners' assertion is that the
use of the LNT model is no longer valid based on various scientific
studies. In particular, the petitioners advance the concept of
radiation hormesis, which posits that low doses of ionizing radiation
protect against the deleterious effects of high doses of radiation and
result in beneficial effects to humans. Therefore, the petitioners
request that the NRC amend its dose limits for occupational workers \3\
and members of the public as follows:
---------------------------------------------------------------------------
\3\ \.\The terms ``occupational worker,'' ``radiation worker,''
``nuclear worker,'' and ``worker'' are used interchangeably in this
document.
---------------------------------------------------------------------------
Maintain worker doses ``at present levels, with allowance
of up to 100 mSv (10 rem) effective dose per year if the doses are
chronic'';
Remove the As Low As Is Reasonably Achievable (ALARA)
principle entirely from the regulations, because they claim that ``it
makes no sense to decrease radiation doses that are not only harmless
but may be hormetic'';
Raise the public dose limits to be the same as the worker
doses, because they claim that ``these low doses may be hormetic''; and
``End differential doses to pregnant women, embryos and
fetuses, and children under 18 years of age.''
II. Background
In 1991, the NRC issued the 10 CFR part 20 final rule, which
established the current regulatory framework for the NRC's radiation
protection regulations.
[[Page 45924]]
All NRC licensees are subject to the NRC's radiation protection
requirements set forth in 10 CFR part 20. These requirements are
designed to protect both members of the public and occupational workers
from harm that could be caused by a licensee's use of radioactive
materials. In accordance with Sec. 20.1101, ``Radiation protection
programs,'' each licensee ``shall develop, document, and implement a
radiation protection program commensurate with the scope and extent of
licensed activities.'' \4\
---------------------------------------------------------------------------
\4\ 10 CFR 20.1101(a).
---------------------------------------------------------------------------
The LNT model has been the underlying premise of much of the NRC's
radiation protection regulations since the late 1950s.\5\ The LNT model
provides that ionizing radiation \6\ is always considered harmful and
that there is no threshold below which an amount of radiation exposure
to the human body is not harmful. The LNT model further holds that
biological damage caused by ionizing radiation (the cancer risk and
adverse hereditary effects) is directly proportional to the amount of
radiation exposure to the human body (response linearity). Thus, the
higher the amount of radiation exposure, or dose,\7\ the higher the
likelihood that the human receptor will suffer biological damage. The
validity of the LNT model has been the subject of dispute within the
scientific community for decades.\8\ The NRC's standards for protection
against radiation, which are contained in 10 CFR part 20, are
underpinned by the LNT model. These radiation protection standards
provide requirements for--
---------------------------------------------------------------------------
\5\ The Atomic Energy Act of 1954 assigned the Atomic Energy
Commission (AEC) the functions of both encouraging the use of
nuclear power and regulating its safety. The AEC was the predecessor
agency to the NRC.
\6\ The terms ``ionizing radiation'' and ``radiation'' are used
interchangeably in this document.
\7\ ``The biological dose or dose equivalent, given in rems or
sieverts (Sv), is a measure of the biological damage to living
tissue as a result of radiation exposure.'' NRC Glossary, Definition
of Dose, https://www.nrc.gov/reading-rm/basic-ref/glossary/dose.html.
\8\ For example, in the October 2015 ACMUI teleconference, Dr.
Zanzonico noted that ``[w]e all recognize that the issue of the
linear no-threshold model of radiation carcinogenesis versus a
hormetic model versus an alternative model remains highly
controversial and really engenders very strong emotions from folks
on different sides of the question.'' ACMUI, Official Transcript of
Proceedings (October 28, 2015), at 18-19.
---------------------------------------------------------------------------
Dose limits for radiation workers and members of the
public,
Monitoring and labeling radioactive materials,
Posting signs in and around radiation areas, and
Reporting the theft or loss of radioactive material.
The petitioners do not dispute that high doses of radiation
exposure are harmful to the human body. Instead, their argument centers
on low doses of radiation exposure, generally doses below 10 rem (100
mSv), the effects of which are difficult to quantify. In this regard,
the petitioners contend that there is a threshold below which radiation
exposure to the human body is not harmful. As described by the
International Commission on Radiological Protection (ICRP) in its
Publication No. 99, ``Low-dose extrapolation of radiation-related
cancer risk,'' the threshold theory posits that ``there is some
threshold dose below which there is either no radiation-related health
detriment or a radiation-related health benefit that outweighs any
detriment. If the threshold was a universal value for all individuals
and all tissues, a consequence of the theory is that, at some point, a
very low dose to any number of people would have no associated risk and
could be ignored.'' \9\
---------------------------------------------------------------------------
\9\ ICRP, ``Low-dose extrapolation of radiation-related cancer
risk,'' Pub. No. 99 (2005), at 38.
---------------------------------------------------------------------------
The petitioners also advance a companion concept to the existence
of a threshold, the radiation hormesis concept (hormesis), which
provides that exposure of the human body to low and very low levels of
ionizing radiation is beneficial to the human body.
III. Petitioners' Assertions
The petitioners request to amend NRC dose limits (dose limit for
occupational workers; dose limit for embryos, fetuses, and pregnant
workers; and the dose limits for the public) as well as to remove the
ALARA principle for the NRC's regulations. The requested amendments to
the regulations were supported by several assertions made by the
petitioners. The NRC reviewed each assertion separately, as outlined in
this section and followed by the NRC's response.
Petitioners' Assertion That LNT Is Not Justified by Current Science
The petitioners assert that current science does not justify the
use of the LNT model and that there is a threshold below which
radiation exposure to the human body is not harmful.
NRC's Response
The NRC does not agree with the petitioners' assertion. Exposure to
ionizing radiation is a known cancer risk factor for humans. The LNT
model assumes that, in the long term, biological damage caused by
ionizing radiation (i.e., cancer risk and adverse hereditary effects)
is directly proportional to the dose. The NRC acknowledges the
difficulties inherent in determining the amount of damage to the human
body caused by low doses of radiation. The NRC, however, does not use
the LNT model to assess the actual risk of low dose radiation. Instead,
the NRC uses the LNT model as the basis for a regulatory framework that
meets the ``adequate protection'' standard of the Atomic Energy Act of
1954, as amended (AEA). Furthermore, the LNT model is applied so that
the framework can be effectively implemented by an agency that
regulates diverse categories of licensees, from commercial nuclear
power plants to individual industrial radiographers and nuclear medical
practices. The NRC's use of the LNT model as the basis for its
radiation protection regulations is premised upon the findings and
recommendations of national and international authoritative scientific
bodies, such as the ICRP, that have expertise in the science of
radiation protection.
The NRC issued the framework for its current 10 CFR part 20
radiation protection regulations in 1991.\10\ The NRC acknowledged the
role of the national and international authoritative scientific bodies
in the 1991 final rule, stating that ``[t]he [U.S. Atomic Energy
Commission] and the NRC have generally followed the basic radiation
protection recommendations of the [ICRP] and its U.S. counterpart, the
National Council on Radiation Protection and Measurements (NCRP), in
formulating basic radiation protection standards.'' The 1991 final rule
explained that the NRC based its radiation protection regulations upon
three assumptions. The first assumption concerned the use of the LNT
model, which was described as follows:
---------------------------------------------------------------------------
\10\ 56 FR 23360; May 21, 1991. Under current NRC regulations,
each NRC licensee must ensure that its operations do not exceed, for
each member of the public, a total effective dose limit of 0.1 rem
(1 mSv) in a calendar year. Sec. 20.1301(a)(1). For occupational
workers, the primary annual dose limit, per licensee, is a total
effective dose equivalent of 5 rems (50 mSv). Sec.
20.1201(a)(1)(i).
The first assumption, the linear nonthreshold dose-effect
relationship, implies that the potential health risk is proportional
to the dose received and that there is an incremental health risk
associated with even very small doses, even radiation doses much
smaller than doses received from naturally occurring radiation
sources. These health risks, such as cancer, are termed stochastic
because they are statistical in nature; i.e., for a given level of
dose, not every person exposed would exhibit the effect.\11\
---------------------------------------------------------------------------
\11\ Id.
The other two assumptions supporting the NRC's radiation
[[Page 45925]]
protection requirements relate to stochastic and nonstochastic effects.
Stochastic risks or effects from exposure to radiation are primarily
the long-term potential for cancer induction and adverse hereditary
effects, while deterministic or nonstochastic risks or effects are
those that can be directly correlated with exposure to high or
relatively high doses of radiation, such as the formation of
cataracts.\12\ The NRC's second assumption was that the severity of a
stochastic effect is independent of, or not related to, the amount of
radiation dose received.\13\ The NRC's third assumption was that there
is an ``apparent threshold; i.e., a dose level below which the
[nonstochastic] effect is unlikely to occur.'' \14\ Therefore, the LNT
model only applies to stochastic effects.
---------------------------------------------------------------------------
\12\ The NRC defines the term ``stochastic effects'' as meaning
``health effects that occur randomly and for which the probability
of the effect occurring, rather than its severity, is assumed to be
a linear function of dose without threshold. Hereditary effects and
cancer incidence are examples of stochastic effects.'' Sec.
20.1003. The NRC defines the term ``nonstochastic effects'' as
meaning ``health effects, the severity of which varies with the dose
and for which a threshold is believed to exist. Radiation-induced
cataract formation is an example of a nonstochastic effect (also
called a deterministic effect).'' Id.
\13\ 56 FR 23360.
\14\ Id.
---------------------------------------------------------------------------
In the 1991 final rule, the NRC stated that these ``assumptions are
necessary because it is generally impossible to determine whether or
not there are any increases in the incidence of disease at very low
doses and low dose rates, particularly in the range of doses to members
of the general public resulting from NRC-licensed activities.'' \15\
The NRC further noted that there is ``considerable uncertainty in the
magnitude of the risk at low doses and low dose rates.'' \16\ The NRC
concluded:
---------------------------------------------------------------------------
\15\ Id.
\16\ Id.
In the absence of convincing evidence that there is a dose
threshold or that low levels of radiation are beneficial, the
Commission believes that the assumptions regarding a linear
nonthreshold dose-effect model for cancers and genetic effects and
the existence of thresholds only for certain nonstochastic effects
remain appropriate for formulating radiation protection standards
and planning radiation protection programs.\17\
---------------------------------------------------------------------------
\17\ Id., at 23360-61.
Thus, the NRC, as a regulator statutorily charged under the AEA
\18\ with protecting the public from radiological harm, determined in
1991 that it was prudent to assume the validity of the LNT model
because of the considerable uncertainty with respect to the effect of
low doses of radiation. The NRC's 1991 final rule was premised, to a
large extent, upon the recommendations of ICRP Publication 26,
``Recommendations of the International Commission on Radiological
Protection'' (1977), several of which, in turn, were premised upon the
LNT model.\19\ The 1991 final rule also referenced the government-wide
``Federal Radiation Protection Guidance for Occupational Exposure,''
signed by President Reagan in 1987, which was similarly premised upon
the ICRP Publication 26 recommendations.\20\
---------------------------------------------------------------------------
\18\ 42 U.S.C. 2011 et seq.
\19\ 56 FR at 23360. In its Publication 26, the ICRP states
``[f]or radiation protection purposes it is necessary to make
certain simplifying assumptions. One such basic assumption
underlying the Commission's recommendations is that, regarding
stochastic effects, there is, within the range of exposure
conditions usually encountered in radiation work, a linear
relationship without threshold between dose and the probability of
an effect.'' ICRP Pub. No. 26.
\20\ 56 FR at 23360. The ``Federal Radiation Protection Guidance
for Occupational Exposure'' concerned the protection of workers from
ionizing radiation and was published in the Federal Register on
January 27, 1987 (52 FR 2822). The guidance was prepared by the
Environmental Protection Agency, the NRC, and several other Federal
agencies having an agency program or function that involved the use
of radioactive material. The guidance stated ``[w]e have considered
these [ICRP] recommendations, among others, and believe that it is
appropriate to adopt the general features of the ICRP approach in
radiation protection guidance to Federal agencies for occupational
exposure;'' and ``[b]ased on extensive but incomplete scientific
evidence, it is prudent to assume that at low levels of exposure the
risk of incurring either cancer or hereditary effects is linearly
related to the dose received in the relevant tissue.'' 52 FR at
2824.
---------------------------------------------------------------------------
The NRC's position remains unchanged from 1991. Convincing evidence
has not yet demonstrated the existence of a threshold below which there
would be no stochastic effects from exposure to low radiation doses. As
such, the NRC's view is that the LNT model continues to provide a sound
basis for a conservative radiation protection regulatory framework that
protects both the public and occupational workers.
Despite the various studies cited by the petitioners, uncertainty
and lack of consensus persists in the scientific community about the
health effects of low doses of radiation. For example, the Health
Physics Society (HPS) has stated that ``[h]ealth risks of radiation
exposure can only be estimated with a reasonable degree of scientific
certainty at radiation levels that are orders of magnitude greater than
limits established by regulation for protection of the public.'' \21\
The HPS has further stated ``that radiation protection literature is
filled with differing views as to the shape of the radiation dose-
response curve at low doses and dose rates.'' \22\ According to HPS,
``[s]ome data support a linear no-threshold model, whereas other data
support models that predict lower estimates of risk and perhaps even a
threshold below which no detectable radiation health risk exists.''
\23\
---------------------------------------------------------------------------
\21\ Position Statement of the Health Physics Society (HPS),
PS008-2, ``Uncertainty in Risk Assessment,'' Adopted July 1993,
Revised April 1995, February 2013.
\22\ HPS PS-008-2 at 2.
\23\ Id.
---------------------------------------------------------------------------
Although there are studies and other scholarly papers that support
the petitioners' assertions, there are also studies and findings that
support the continued use of the LNT model, including those by national
and international authoritative scientific advisory bodies. Those
authoritative scientific advisory bodies that have a specialty in the
subject matter area of radiation protection include, domestically, the
federally chartered National Academy of Sciences (NAS) \24\ and
NCRP,\25\ and, internationally, the ICRP and the International Atomic
Energy Agency (IAEA). All four of these bodies support the continued
use of the LNT model. It has been the longstanding practice of the NRC
to generally place significant weight on the recommendations of these
authoritative scientific advisory bodies.\26\
---------------------------------------------------------------------------
\24\ The NAS ``is a private, non-profit society of distinguished
scholars. Established by an Act of Congress . . . the NAS is charged
with providing independent, objective advice to the nation on
matters related to science and technology. Scientists are elected by
their peers to membership in the NAS for outstanding contributions
to research.'' http://www.nasonline.org/about-nas/mission/.
\25\ The NCRP is a private, non-profit corporation whose mission
is ``to formulate and widely disseminate information, guidance and
recommendations on radiation protection and measurements which
represent the consensus of leading scientific thinking.'' http://ncrponline.org/about/mission/.
\26\ E.g., 56 FR at 23360.
---------------------------------------------------------------------------
National Authoritative Scientific Advisory Bodies Favoring Continued
Use of LNT
In 2006, the NAS published its Biological Effects of Ionizing
Radiation (BEIR) VII report, ``Health Risks from Exposure to Low Levels
of Ionizing Radiation,'' the seventh in a series of reports that
concern the health effects from low doses of radiation, and by
extension, the appropriateness of the LNT model.\27\ The report was
prepared by the Committee to Assess Health Risks from Exposure to Low
Levels of Ionizing
[[Page 45926]]
Radiation that was established by NAS for the purpose of advising ``the
U.S. government on the relationship between exposure to ionizing
radiation and human health.'' \28\ The BEIR VII report focused on
health effects from low doses of radiation (below 10 rem or 100 mSv)
\29\ and updated the findings of the previous report of low dose
radiation, the 1990 BEIR V.
---------------------------------------------------------------------------
\27\ NAS, ``Health Risks from Exposure to Low Levels of Ionizing
Radiation, BEIR VII--Phase 2'' (2006) (NAS BEIR VII). The BEIR VII
report may be viewed online at https://www.nap.edu/catalog/11340/health-risks-from-exposure-to-low-levels-of-ionizing-radiation. The
NRC was one of several Federal agencies that provided funding to NAS
for the BEIR VII study.
\28\ Id., at vii.
\29\ In its report, the BEIR VII committee ``defined low dose as
doses in the range of near zero up to about 100 mSv (0.1 Sv) of low-
[linear energy transfer] radiation.'' NAS BEIR VII at 2. The NCRP
has considered a ``very low dose'' to be a dose below 1 rem or 10
mSv. NCRP, ``Implications of Recent Epidemiologic Studies for the
Linear Nonthreshold Model and Radiation Protection,'' Commentary 27
(April 24, 2018), at 66.
---------------------------------------------------------------------------
The BEIR VII committee analyzed epidemiologic data and biological
data, including a study of the survivors of the Hiroshima and Nagasaki
atomic bomb attacks and studies of cancer in children. The BEIR VII
committee found ``that the preponderance of information indicates that
there will be some risk, even at low doses'' and ``that there is no
compelling evidence to indicate a dose threshold below which the risk
of tumor induction is zero.'' \30\ The BEIR VII committee further found
``[w]hen the complete body of research on this question is considered,
a consensus view emerges. This view says that the health risks of
ionizing radiation, although small at low doses, are a function of
dose.'' \31\ The BEIR VII committee concluded that ``current scientific
evidence is consistent with the hypothesis that there is a linear, no-
threshold dose-response relationship between exposure to ionizing
radiation and the development of cancer in humans.'' \32\
---------------------------------------------------------------------------
\30\ NAS BEIR VII at 10.
\31\ Id.
\32\ Id., at 323.
---------------------------------------------------------------------------
Following the publication of BEIR V, the NCRP updated its radiation
protection recommendations in its 1993 report, NCRP Report No. 116,
``Limitation of Exposure to Ionizing Radiation.'' Although the NCRP
acknowledged that it could not exclude the possibility of no health
risk from low doses, the NCRP expressed its reliance on the LNT model
as the basis for several of its recommendations,
Based on the hypothesis that genetic effects and some cancers
may result from damage to a single cell, the Council assumes that,
for radiation-protection purposes, the risk of stochastic effects is
proportional to dose without threshold, throughout the range of dose
and dose rates of importance in routine radiation protection.
Furthermore, the probability of response (risk) is assumed, for
radiation protection purposes, to accumulate linearly with dose.\33\
---------------------------------------------------------------------------
\33\ NCRP, ``Limitation of Exposure to Ionizing Radiation,''
Report No. 116 (1993), at 10 (emphasis in the original).
In 2001, the NCRP published Report No. 136, ``Evaluation of the
Linear-Nonthreshold Dose-Response Model for Ionizing Radiation,'' which
reported the work of the NCRP's Scientific Committee 1-6. Scientific
Committee 1-6 was charged with reassessing ``the weight of scientific
evidence for and against the linear-nonthreshold dose-response model,
without reference to policy implications.'' \34\ The NCRP Report No.
136 explained that the existence of the LNT model for low radiation
doses must be extrapolated from data showing adverse health effects
from high radiation doses and that there were differing sets of data
that both showed evidence for and against the LNT model. Nevertheless,
the NCRP noted ``that radiation imparts its energy to living matter
through a stochastic process, such that a single ionizing track has a
finite probability of depositing enough energy in traversing a cell to
damage a critical molecular target within the cell, such as DNA.'' \35\
After a comprehensive review of many studies, the NCRP concluded that
``[a]lthough other dose-response relationships for the mutagenic and
carcinogenic effects of low-level radiation cannot be excluded, no
alternate dose-response relationship appears to be more plausible than
the linear-nonthreshold model on the basis of present scientific
knowledge.'' \36\
---------------------------------------------------------------------------
\34\ NCRP, ``Evaluation of the Linear-Nonthreshold Dose-Response
Model for Ionizing Radiation,'' Report No. 136 (2001), at 1.
\35\ Id., at 208.
\36\ Id., at 7. See also id., at 48-49 (The NCRP also stated
``[t]herefore, if radiation-induced cancer results directly from the
induction of mutations involved in the oncogenic pathway, the data
reported do not support the existence of a threshold.''); and id.,
at 77 (The NCRP also noted that ``the majority of studies report
linear dose-response relationships in the lower dose range with the
coefficient being quite similar to the alpha coefficient of the in
vitro linear-quadratic dose-response curves.'').
---------------------------------------------------------------------------
In a May 2017 article published in the ``International Journal of
Radiation Biology,'' the NCRP's president, Dr. John D. Boice, Jr.,
supports the continued use of the LNT model. Dr. Boice states that
``[t]he LNT model, at least at the current time, has been useful in
radiation protection, e.g., a safety culture exists that encompasses
the principle of `as low as reasonably achievable' (ALARA) considering
financial and societal issues,'' and in this context, notes that
``worker exposures have dropped dramatically over the years.'' \37\
Given that epidemiological studies may not demonstrate the validity of
the LNT model for low doses (below 100 mSv), Dr. Boice further states
that the use of the LNT model combined with the technical and
professional judgment of a competent regulator provides ``a prudent
basis for the practical purposes of radiological protection.'' \38\ In
his conclusion, Dr. Boice emphasized that the LNT model is not an
appropriate mechanism to assess radiological risk but is the most
appropriate model currently available for a system of radiological
protection when coupled with the appropriate regulatory and technical
judgment.\39\
---------------------------------------------------------------------------
\37\ J. Boice, Jr., ``The linear nonthreshold (LNT) model as
used in radiation protection: An NCRP update,'' International
Journal of Radiation Biology, Vol. 93, No. 10 (2017), at 1080
(Boice).
\38\ Id.
\39\ Id., at 1089.
---------------------------------------------------------------------------
In a study funded by the NRC, the NCRP reevaluated the LNT model
based on new studies completed since the publication of NCRP Report No.
136 in June 2001. In April 2018, the NCRP released Commentary 27,
``Implications of Recent Epidemiologic Studies for the Linear-
Nonthreshold Model and Radiation Protection,'' which provides a
detailed assessment of currently available epidemiological evidence and
concludes that ``the LNT model (with the steepness of the dose-response
slope perhaps reduced by a DDREF [dose and dose rate effectiveness
factor] factor) should continue to be utilized for radiation protection
purposes.'' \40\ The Commentary explains that ``[w]hile the LNT model
is an assumption that likely cannot be scientifically validated by
radiobiologic or epidemiologic evidence in the low-dose range, the
preponderance of epidemiologic data is consistent with the LNT
assumption, although there are a few notable exceptions.'' \41\ The
Commentary concludes that the ``current judgment by national and
international scientific committees is that no alternative dose-
response relationship appears more pragmatic or prudent for radiation
protection purposes than the LNT model on the basis of available data,
recognizing that the risk [for doses]
[[Page 45927]]
<100 mGy [<10 rad] is uncertain but small.'' \42\
---------------------------------------------------------------------------
\40\ NCRP, ``Implications of Recent Epidemiologic Studies for
the Linear Nonthreshold Model and Radiation Protection,'' Commentary
27 (April 24, 2018), at 139. The acronym ``DDREF'' refers to the
dose and dose-rate effectiveness factor, and is used to extrapolate
the risk of cancer induction from high doses received acutely, and
thus measurable, to those low doses, which cannot be measured and
are the focus of the LNT model. Id., at 20 22-23, and 34.
\41\ Id., at 140.
\42\ Id.
---------------------------------------------------------------------------
International Authoritative Scientific Advisory Bodies Favoring
Continued Use of LNT
The ICRP, in its Publication No. 99, ``Low-dose Extrapolation of
Radiation-related Cancer Risk,'' stated that ``we are uncertain about
the likelihood of a dose threshold, and that, in addition, if there
should be a dose threshold, we are uncertain about what dose level it
would be.'' \43\ The ICRP further stated that ``the mechanistic and
experimental data discussed in this monograph tend to give weight to a
non-threshold model, as do the solid tumour data in the Japanese atomic
bomb study.'' \44\ The ICRP concluded that the ``LNT theory remains the
most prudent risk model for the practical purposes of radiological
protection.'' \45\ The ICRP reaffirmed this conclusion in its
Publication No. 103, ``The 2007 Recommendations of the International
Commission on Radiological Protection'' (2007).\46\ In Publication No.
103, the ICRP acknowledged that the LNT model was not ``universally
accepted as a biological truth'' and that the possibility of a low-dose
threshold could not be ruled out, but ``because we do not actually know
what level of risk is associated with very-low-dose exposure, [the LNT
model] is considered to be a prudent judgement for public policy aimed
at avoiding unnecessary risk from exposure.'' \47\ While a 2005 joint
French Academy of Sciences and National Academy of Medicine review
expressed ``doubts on the validity of using LNT for evaluating the
carcinogenic risk of low doses,'' this review noted that ``[t]he LNT
concept can be a useful pragmatic tool for assessing rules in
radioprotection for doses above 10 mSv [1 rem].'' \48\
---------------------------------------------------------------------------
\43\ ICRP, ``Low-dose Extrapolation of Radiation-related Cancer
Risk,'' Pub. No. 99 (2005), at 108.
\44\ Id.
\45\ Id., at 113.
\46\ ICRP, ``The 2007 Recommendations of the International
Commission on Radiological Protection,'' Pub. No. 103 (2007), at 36
and 38, 65-67.
\47\ Id., at A178 and A180.
\48\ Academy of Sciences and National Academy of Medicine
(France), ``Dose-Effect Relationships and Estimation of the
Carcinogenic Effects of Low Doses of Ionizing Radiation'' (2005), at
5.
---------------------------------------------------------------------------
The IAEA, in its 1997 nuclear safety review (published in August
1998), stated that ``some researchers have interpreted experimental
results and epidemiological findings as providing evidence that low
doses of radiation are much more harmful than the LNT hypothesis
implies. A number of mechanisms have been proposed by which this might
occur, a recent example being the phenomenon of genomic instability.''
\49\ The IAEA report concluded that ``[f]rom the evidence available at
the present time, however, the LNT hypothesis continues to seem the
most radiobiologically defensible basis for radiation protection
recommendations. It is also a workable hypothesis that can underpin
systems of regulation which, when applied reasonably, provide sound and
sensible management of the risks from radiation.'' \50\ The current
IAEA radiation safety standards, Radiation Protection and Safety of
Radiation Sources: International Basic Safety Standards, published in
2014, relies upon the LNT model, stating that the LNT model ``is the
working hypothesis on which the IAEA's safety standards are based. It
is not proven--indeed it is probably not provable--for low doses and
dose rates, but it is considered the most radiobiologically defensible
assumption on which to base safety standards.'' \51\
---------------------------------------------------------------------------
\49\ IAEA, ``Measures to Strengthen International Co-Operation
in Nuclear, Radiation and Waste Safety, Nuclear Safety Review for
the Year 1997'' (August 1998), Attachment at 32.
\50\ Id.
\51\ IAEA, ``Radiation Protection and Safety of Radiation
Sources: International Basic Safety Standards, General Safety
Requirements Part 3'' (2014), at 401.
---------------------------------------------------------------------------
Comments of Federal Agencies
In addition to the findings of the national and international
authoritative scientific advisory bodies, three Federal agencies
provided comments on the petitions and supported the continued use of
the LNT model as the basis for the NRC's radiation protection program.
The three agencies are the National Cancer Institute (NCI), National
Institutes of Health, Department of Health and Human Services; National
Institute for Occupational Safety and Health (NIOSH), Centers for
Disease Control and Prevention, Department of Health and Human
Services; and the Radiation Protection Division, Office of Air and
Radiation, Environmental Protection Agency (EPA). Furthermore, the
NRC's Advisory Committee on the Medical Uses of Isotopes (ACMUI) \52\
recommends that the NRC continue to rely upon the LNT model.
---------------------------------------------------------------------------
\52\ The ACMUI is an official advisory body to the NRC
established in accordance with the Federal Advisory Committee Act
(FACA), 5 U.S.C. App. 2. The ACMUI advises the NRC on policy and
technical issues that arise in the regulation of the medical uses of
radioactive material in diagnosis and therapy.
---------------------------------------------------------------------------
NCI provided detailed comments during the 2015 public comment
period for the petitions.\53\ In response to the petitioners'
assertions that several epidemiologic studies showed that individuals
exposed to higher doses of radiation were less likely or no more likely
to develop cancer than those who received lower doses of radiation,
NCI, in its comments, noted the limitations of such studies. NCI
explained that ``because epidemiologic studies are observational and
not controlled experiments, differences in risks in exposed and
unexposed may reflect differences in life style factors such as smoking
and may not necessarily result from radiation exposure.'' \54\ In
addition, NCI stated in its comments:
---------------------------------------------------------------------------
\53\ NCI, A. Berrington de Gonz[aacute]lez, et al.,
``Contribution to Nuclear Regulatory Commission (NRC) comments on
petitions on linear no-threshold model and standards for protection
against radiation'' (November 19, 2015) (NCI 2015). The specific
component of NCI that provided the comments was the Radiation
Epidemiology Branch, Division of Cancer Epidemiology and Genetics.
\54\ Id. at 1. See also Boice at 1089 (``All models are wrong,
but some are useful for radiation protection. LNT is an assumption.
It is unlikely to be scientifically validated in the low-dose
domain, and not by epidemiology'').
the petitions are selective in citing studies that appear to support
hormesis (or a threshold) and omitting mention of the many studies
that provide evidence of a dose-response at low doses. In some
cases, analyses published many years ago are cited, when more recent
analyses based on current follow-up of the same populations, often
with improved dose estimates, do not support their claims.\55\
---------------------------------------------------------------------------
\55\ NCI 2015, at 1.
In this regard, NCI, in its comments, provided several examples of
such studies and the more recent follow-up analyses that did not
support the petitioners' assertions but provided ``evidence of a dose-
response at low doses,'' \56\ especially among children.
---------------------------------------------------------------------------
\56\ Id., at 2.
---------------------------------------------------------------------------
NIOSH also provided detailed comments during the 2015 public
comment period.\57\ NIOSH, in its comments, noted that the ``lines of
evidence given by the petitioners are not new and are fundamentally the
same as those rejected by the BEIR VII committee.'' \58\ NIOSH's
comments are based, in part, upon a large study of nuclear workers,
completed in 2015, which found that even tiny doses slightly boost the
risk of leukemia (the study has been informally referred to as the
international nuclear workers or
[[Page 45928]]
``INWORKS'' study).\59\ This study included within its cohort over
308,000 nuclear industry workers from the United States, the United
Kingdom, and France.\60\ The INWORKS study's authors stated that ``[i]n
summary, this study provides strong evidence of an association between
protracted low dose radiation exposure and leukemia mortality.'' \61\
---------------------------------------------------------------------------
\57\ NIOSH, S. Toye, ``Comments of the National Institute for
Occupational Safety and Health on the Nuclear Regulatory Commission
Notice of Docketing and Request for Comment on Linear No-Threshold
Model and Standards for Protection Against Radiation,'' September
11, 2015 (NIOSH 2015).
\58\ Id., at 2.
\59\ K. Leuraud et al., ``Ionising Radiation and Risk of Death
from Leukaemia and Lymphoma in Radiation-monitored Workers
(INWORKS): An International Cohort Study, Lancet Haematology, Vol.
2'' (June 2015).
\60\ Id., at 278.
\61\ Id., at 280.
---------------------------------------------------------------------------
NIOSH, in its comments, further stated that its researchers and
others
conducted meta-analyses of cancer risk from low-dose exposures in a
variety of populations receiving protracted exposure to external
ionizing radiation [Jacob et al. 2009; Daniels and Schubauer-Berigan
2011]. These meta-analyses concluded that there is a small but
significant excess risk of solid cancer and leukemia, respectively,
at occupational doses received during a typical working lifetime
[Walsh 2011].\62\
---------------------------------------------------------------------------
\62\ NIOSH 2015, at 2.
The NIOSH researchers and others also published two studies
describing cancer risk among nuclear workers at four Department of
Energy sites and the Portsmouth Naval Shipyard. According to the NIOSH
comments, a pooled cohort study included nearly 120,000 nuclear workers
from these five sites (these workers were also included in the larger
INWORKS study). The authors of the pooled cohort study found that the
``excess relative risk (ERR) was significantly associated with
occupational radiation dose for all non-smoking related cancers
combined.'' \63\ NIOSH stated that ``[t]hese findings suggest that the
risk of these cancers rises by 0.7% and 2.0% (respectively) for every
10 millisieverts (mSv; 1 rem) increase in dose.'' \64\ NIOSH, in its
comments, stated that the LNT model presents ``a reasonable framework
for protecting workers from excess risks associated with occupational
exposure to ionizing radiation'' \65\ and concluded with a
recommendation that the NRC retain the current radiation protection
standards.\66\
---------------------------------------------------------------------------
\63\ Id., at 2-3.
\64\ Id., at 3. The NRC's general public and occupational dose
limits are 1 mSv (0.1 rem) and 0.05 Sv (5 rem), respectively. See
Sec. 20.1201(a)(1) (occupational dose limit) and Sec.
20.1301(a)(1) (public dose limit).
\65\ NIOSH 2015, at 3.
\66\ Id., at 6.
---------------------------------------------------------------------------
Similarly, in its comments, EPA recommended that the NRC deny the
petitions. EPA stated the following:
Within limitations imposed by statistical power, the available
(and extensive) epidemiological data are broadly consistent with a
linear dose-response for radiation cancer risk at moderate and low
doses. Biophysical calculations and experiments demonstrate that a
single track of ionizing radiation passing through a cell produces
complex damage sites in DNA, unique to radiation, the repair of
which is error-prone. Thus, no threshold for radiation-induced
mutations is expected, and, indeed, none has been observed.\67\
---------------------------------------------------------------------------
\67\ EPA, J. Edwards, ``Comments on Linear No-Threshold Model
and Standards for Protection Against Radiation'' (October 7, 2015),
at 1.
EPA, in its comments, referenced four epidemiological studies
conducted after BEIR VII, including the INWORKS study, two studies of
``residents along the Techa River in Russia who were exposed to
radionuclides from the Mayak Plutonium Production Plant,'' and a study
of children who had received computed tomography (CT) scans.\68\ The
EPA stated that ``[t]hese studies have shown increased risks of
leukemia and other cancers at doses and dose rates below those which
LNT skeptics have maintained are harmless--or even beneficial.'' \69\
EPA, in its comments, referenced the findings of the various domestic
and international bodies, including the NAS and concluded,
---------------------------------------------------------------------------
\68\ Id.
\69\ Id.
[g]iven the continuing wide consensus on the use of LNT for
regulatory purposes as well as the increasing scientific
confirmation of the LNT model, it would be unacceptable to the EPA
to ignore the recommendations of the NAS and other authoritative
sources on this issue.\70\
---------------------------------------------------------------------------
\70\ Id., at 2.
EPA concluded that it could not endorse basing radiation protection
on the petitioners' proposals, which it characterized as ``poorly
supported and highly speculative.'' \71\
---------------------------------------------------------------------------
\71\ Id.
---------------------------------------------------------------------------
The ACMUI advises the NRC on policy and technical issues that arise
in the regulation of the medical uses of radioactive material in
diagnosis and therapy. The ACMUI is a committee authorized under the
FACA, which regulates the formation and operation of advisory
committees by Federal agencies. The ACMUI membership includes health
care professionals from various disciplines, who comment on changes to
NRC regulations and guidance; evaluate certain non-routine uses of
radioactive material; provide technical assistance in licensing,
inspection, and enforcement cases; and bring key issues to the
attention of the Commission for appropriate action. Subsequent to the
filing and docketing of the petitions, the ACMUI formed a subcommittee
to review and comment on the petitions. The ACMUI held a public
teleconference meeting on October 28, 2015, to vote on the
subcommittee's draft report.\72\ The draft subcommittee report was
approved by the ACMUI and issued as final on that same date.\73\ The
ACMUI report stated that determining the `` `correct' dose-response
model for radiation carcinogenesis remains an unsettled scientific
question.'' \74\ Although the report acknowledged that there ``is a
large, and growing, body of scientific literature as well as
mechanistic considerations'' that question the accuracy of the LNT
model, the ACMUI determined that ``very large-scale epidemiological
studies with long-term follow-up would be needed to actually quantify
any such risks or benefits'' and that ``such studies may be
logistically and financially prohibitive.'' \75\ According to the ACMUI
report, ``a mathematical extrapolation model remains the only practical
approach to estimating the presumed excess cancer risk from low-dose
radiation.'' Therefore, the ``dose-response data derived from
epidemiological studies of human cohorts, such as the [1945 Hiroshima
and Nagasaki atomic bombing] survivors exposed to high-dose radiation,
are largely consistent with an LNT model.'' \76\ In making its
recommendation, the ACMUI stated that it ``recommends that, for the
time being and subject to reconsideration as additional scientific
evidence becomes available, the NRC continue to base the formulation of
radiation protection standards on the LNT model.'' \77\
---------------------------------------------------------------------------
\72\ The meeting notice for the October 28, 2015, meeting was
published in the Federal Register on September 8, 2015 (80 FR
53896).
\73\ ACMUI, ``Final Report on the Hormesis/Linear No-Threshold
Petitions'' (October 28, 2015), at 1.
\74\ Id.
\75\ Id., at 1-2.
\76\ Id., at 2.
\77\ Id., at 1.
---------------------------------------------------------------------------
Conclusion
Based upon the current state of science, the NRC concludes that the
actual level of risk associated with low doses of radiation remains
uncertain and some studies, such as the INWORKS study, show there is at
least some risk from low doses of radiation. Moreover, the current
state of science does not provide compelling evidence of a threshold,
as highlighted by the fact that no national or international
authoritative scientific advisory bodies have concluded that such
evidence exists. Therefore, based upon the stated
[[Page 45929]]
positions of the aforementioned advisory bodies; the comments and
recommendations of NCI, NIOSH, and the EPA; the October 28, 2015,
recommendation of the ACMUI; and its own professional and technical
judgment, the NRC has determined that the LNT model continues to
provide a sound regulatory basis for minimizing the risk of unnecessary
radiation exposure to both members of the public and occupational
workers. Consequently, the NRC will retain the dose limits for
occupational workers and members of the public in 10 CFR part 20
radiation protection regulations.
Petitioners' Assertion That Hormesis Disproves the LNT Model
The petitioners advance the concept of hormesis, ``in which low
levels of potentially stressful agents, such as toxins, other
chemicals, ionizing radiation, etc., protect against the deleterious
effects that high levels of these stressors produce and result in
beneficial effects (e.g., lower cancer rates).'' \78\ Thus, the
petitioners assert that low doses of radiation are beneficial to humans
in that such doses may enhance the immune response or DNA repair
processes. The petitioners request that the NRC amend its regulations
to raise the dose limit for members of the public to be the same as the
occupational dose limit.\79\
---------------------------------------------------------------------------
\78\ Marcus petition (PRM-20-28), at 1-2.
\79\ Id., at 7 (``Why deprive the public of the benefits of low
dose radiation?'').
---------------------------------------------------------------------------
NRC's Response
There is scientific uncertainty and no compelling evidence as to
whether the hormesis concept is valid for application to radiation
protection requirements. None of the national and international
authoritative scientific advisory bodies described above support the
hormesis concept as a regulatory model for radiation protection. Of
note, the BEIR VII report produced by NAS included a strong conclusion
against applying the hormesis concept to radiation protection:
Although examples of apparent stimulatory or protective effects
can be found in cellular and animal biology, the preponderance of
available experimental information does not support the contention
that low levels of ionizing radiation have a beneficial effect. The
mechanism of any such possible effect remains obscure. At this time,
the assumption that any stimulatory hormetic effects from low doses
of ionizing radiation will have a significant health benefit to
humans that exceeds potential detrimental effects from radiation
exposure at the same dose is unwarranted.\80\
---------------------------------------------------------------------------
\80\ NAS BEIR VII, at 315.
Similarly, the NCRP has found that there is not strong support for
the hormesis concept in the scientific literature.\81\ The NRC has
determined that it is prudent to continue to rely upon the LNT model as
a basis for the NRC's radiation protection regulations. Consequently,
the NRC will retain the dose limits for occupational workers and
members of the public in 10 CFR part 20 radiation protection
regulations.
---------------------------------------------------------------------------
\81\ NCRP Report No. 136, at 196; see also NCI 2015, at 3
(``there is little data to suggest a threshold in dose, or possible
hormetic (beneficial) effects of low-dose radiation exposure'').
---------------------------------------------------------------------------
Petitioners' Assertion That the NRC has a Conflict of Interest
The petitioners suggest a conflict of interest, because the NRC is
one of the Federal agencies that funded the development of the BEIR VII
report by the NAS and has funded, and is funding, research by the NCRP.
NRC's Response
Sections 31.a and 161.c of the AEA authorize the NRC to enter into
arrangements with organizations such as the NAS and the NCRP.
Specifically, section 31.a of the AEA authorizes the NRC to enter into
arrangements, with either public or private institutions or persons,
for research and development and to expand theoretical and practical
knowledge in the various fields specified in section 31.a, including
radiological health and safety.\82\ Additionally, section 161.c
authorizes the NRC to ``make such studies and investigations, obtain
such information . . . as the Commission may deem necessary or proper
to assist it in exercising any authority provided in [the AEA].'' \83\
---------------------------------------------------------------------------
\82\ 42 U.S.C. 2051(a).
\83\ 42 U.S.C. 2201(c).
---------------------------------------------------------------------------
The petitioners merely allege a conflict of interest. The NRC did
not influence or direct the findings of either the NAS or the NCRP, and
the NRC is not aware of any irregularities in the methods invoked by
NAS or NCRP technical experts who analyzed the data and prepared the
respective reports. The petitioners did not present any evidence to the
contrary. Moreover, the petitioners did not demonstrate that the
findings of either the BEIR VII report or any of the various NCRP
reports that were funded in part by the NRC are either technically or
scientifically unsound. The NRC will continue to review and consider
recommendations on radiation protection regulations provided by
national and international authoritative scientific advisory bodies.
Petitioners' Assertion That the Cost of Compliance With LNT-Based
Regulations Is Enormous
The petitioners assert that the cost of complying with LNT-based
regulations is ``enormous'' and ``incalculable.''
NRC's Response
In 1991, the NRC issued the 10 CFR part 20 final rule, which
established the current regulatory framework for the NRC's radiation
protection regulations. In issuing that final rule, the Commission
concluded that the rule ``provides for a substantial increase in the
overall protection of the public health and safety and that the direct
and indirect costs of its implementation are justified in terms of the
quantitative and qualitative benefits associated with the rule.'' \84\
Although the NRC acknowledges the costs involved in complying with its
regulations, the NRC continues to conclude that its regulatory
provisions that rely on LNT, such as the ALARA concept, remain both
beneficial, in terms of the health and safety benefits they provide to
both members of the public and occupational workers, and are cost-
justified.\85\ The petitioners have not provided any new information
that would cause the NRC to revisit its findings with respect to cost
that it made in 1991.
---------------------------------------------------------------------------
\84\ 56 FR at 23389.
\85\ The NRC regulations define ALARA as ``making every
reasonable effort to maintain exposures to radiation as far below
the dose limits in this part as is practical consistent with the
purpose for which the licensed activity is undertaken.'' Sec.
20.1003. Those individuals and entities that hold NRC licenses are
required, ``to the extent practical,'' to incorporate ALARA into
their procedures and engineering controls in accordance with Sec.
20.1101(b). The NRC's Regulatory Guide (RG) 8.10, ``Operating
Philosophy for Maintaining Occupational and Public Radiation
Exposures As Low As Is Reasonably Achievable,'' Rev. 2 (August
2016), provides guidance to NRC licensees on complying with the
ALARA requirement. Other NRC regulatory guides provide additional
ALARA guidance to licensees in specific categories, e.g., RG 8.8
(power reactor licensees) and RG 8.18 (medical licensees).
---------------------------------------------------------------------------
Moreover, in the 1991 final rule, the Commission further noted that
if it had determined that the rule was not cost-justified, the
Commission would have still issued the rule ``because the changes made
to part 20 also amount to a redefinition of the level of adequate
protection.'' \86\ ``Adequate protection'' is the NRC's fundamental
safety standard and is derived from various provisions of the AEA.\87\
An ``adequate protection''
[[Page 45930]]
finding means that the Commission or the NRC staff, if appropriate, has
determined that a given requirement is the minimum necessary for public
health and safety. Applicable case law holds that ``adequate
protection'' findings are made without regard to cost. In this regard,
the United States Court of Appeals, District of Columbia Circuit stated
that--
---------------------------------------------------------------------------
\86\ 56 FR at 23389.
\87\ E.g., Section 182a. of the AEA, with respect to reactor
applications, requires the Commission to find that ``the utilization
or production of special nuclear material will be in accord with the
common defense and security and will provide adequate protection to
the health and safety of the public.'' 42 U.S.C. 2232(a).
Section 182(a) of the Act commands the NRC to ensure that any
use or production of nuclear materials ``provide[s] adequate
protection to the health or safety of the public.'' 42 U.S.C.
2232(a). In setting or enforcing the standard of ``adequate
protection'' that this section requires, the Commission may not
consider the economic costs of safety measures. The Commission must
determine, regardless of costs, the precautionary measures necessary
to provide adequate protection to the public; the Commission then
must impose those measures, again regardless of costs, on all
holders of or applicants for operating licenses.\88\
---------------------------------------------------------------------------
\88\ Union of Concerned Scientists v. NRC, 824 F.2d 108, 114
(D.C. Cir. 1987).
The NRC is mandated under the AEA to impose requirements that it
determines to be necessary for adequate protection of public health and
safety regardless of cost. As set forth earlier in this document, the
consensus of the various international and domestic authoritative
scientific advisory bodies, as well as the NCI, NIOSH, and EPA, is that
the LNT model should remain the basis for radiological protection
regulations. Based upon these external organizations' recommendations,
the recommendation of the ACMUI, and the professional and technical
judgment of the NRC, those regulations that are based upon the LNT
model remain necessary for adequate protection. Therefore, the NRC will
continue to use the LNT model as the basis for its current radiation
protection regulations in 10 CFR part 20.
IV. Public Comments on the Petition
On June 23, 2015, the NRC published in the Federal Register a
notice of docketing of the three petitions, and requested public
comment with the comment period ending on September 8, 2015.\89\ On
August 21, 2015, the NRC extended the comment period to November 19,
2015, to allow more time for members of the public to develop and
submit their comments.\90\ The NRC received over 3,200 comment
submissions, with 635 of those comment submissions being unique,
including comments from certified health physicists, nuclear medical
professionals, other scientific professionals, scientific associations,
Federal agencies, and concerned citizens.
---------------------------------------------------------------------------
\89\ 80 FR 35870.
\90\ 80 FR 50804.
---------------------------------------------------------------------------
In determining the appropriate response to the petitions, the NRC
carefully reviewed the public comments. To simplify the analysis, the
NRC grouped all comment letters into two main groups: Those that
opposed the petitions and those that supported them. A description of
the comments in both groups and the NRC's responses are provided as
follows.
Comments Opposed to the Petitions
Comments: There were 535 unique comment submissions that opposed
the petitioners' recommendation to discontinue use of the LNT model as
a basis for the NRC's radiation protection regulations. Some of these
commenters stated that the petitioners did not provide sufficient
evidence to support changing the technical basis regarding radiation
exposure from the LNT model to the hormesis concept. One commenter
stated that the proposal to increase allowable public radiation doses
to the same as those of nuclear industry workers neglects the fact that
the workers made a voluntary choice to work in the nuclear industry,
and thus be subject to accompanying exposure to radiation, whereas the
general public did not make that choice. Another commenter stated that
the LNT model is satisfactory and that there is no substantial science
upon which to base any change to the current 10 CFR part 20 public and
occupational dose limits. One commenter stated that no threshold exists
because every organism's adaptive response varies considerably, with
the very young being the most vulnerable. Another commenter stated that
``the existing standard needs to be retained, or at least, retained
unless and until an undeniable and clear preponderance of the evidence
indicates that the existing standard definitely should be replaced by
some specific alternative.''
Response: The NRC agrees that the petitions should be denied. The
NRC's rationale is set forth earlier in this document. Therefore, the
NRC will not amend its radiation protection regulations in response to
the petitioners' requests.
Comments Supporting the Petitions
There were 100 unique comment submissions that agreed with the
petitioners. These commenters provided varied responses, and so to
simplify the analysis and address each type of comment, the NRC grouped
the comments by subject and separated them into subject areas. A review
of the comments and the NRC's responses follow.
Comments Supporting the Petitions--General Comments; Assertions That
NRC Regulations Lead to Unjustified Fear of Radiation by Authorities
and the Public
Comment: The NRC received several comments that expressed support
for the petitions without providing a specific rationale.
Response: These comments expressed support for the petitions in
general terms and did not provide any further rationale or explanation
for why the petitions should be considered for rulemaking. Therefore,
no detailed response is being provided separate from the justification
presented above for the NRC's denial of the petitions.
Comment: The NRC received a comment that supports the petitions
based on the commenter's experiences working in the radiation
protection field. The commenter concludes that, outside of individuals
with experience in a nuclear facility, most individuals do not have
proper authority or experience to appropriately determine proper
radiation protection practices.
Response: The NRC interprets this comment to mean that those who
lack experience working in a nuclear facility cannot properly
understand radiation protection principles. The NRC disagrees with this
comment. The NRC's radiation protection regulations, policies, and
guidance are informed by operational experience, the findings and
recommendations of national and international authoritative scientific
advisory bodies, and academic and government research.
Comment: Several commenters expressed concern that the LNT model
and the ALARA concept create an unjustified fear of radiation exposure
that could lead to authorities directing mass evacuations in the event
of a major nuclear incident. The commenters expressed concern that such
a mass evacuation would result in casualties, some of which may be
caused by mass panic, and also result in significant socioeconomic
costs.
Response: The NRC disagrees with this comment. The appropriate
Federal, State, and local decision-makers take many factors into
account when deciding to recommend or order an evacuation, including
the size and nature of the incident and the potential impacts on
affected communities. With
[[Page 45931]]
respect to evacuation decisions, the State and local authorities who
make those decisions are not subject to the AEA or to the NRC's ALARA
requirement.
Moreover, ALARA is an operating principle designed to minimize the
potential stochastic effects of low levels of ionizing radiation that
members of the public and occupational workers may be exposed to as a
result of routine licensee activities. The long-term potential (in
terms of years or even decades) for the induction of cancer from these
routine activities is the primary stochastic effect that the
application of ALARA seeks to minimize. In an emergency situation
involving the release of radioactive material, the overriding concern
associated with evacuation decisions is to avert potential acute
radiation exposure.
The NRC has concluded that the selection of a specific dose
response model, LNT in this case, and the ALARA concept, which is
premised upon the LNT model, do not lead directly to an unjustified
fear of radiation, and thereby do not directly contribute to evacuation
casualties and associated socioeconomic costs after a nuclear incident.
The NRC's rationale for continuing to use the LNT model as the basis
for its radiation protection regulations is set forth earlier in this
document. The costs of mass evacuation scenarios described by the
commenters do not provide an adequate basis to discontinue the use of
the LNT model.
Comment: One commenter asserted that ``there may be cases where, in
efforts to minimize even low radiation exposure to workers and the
public in the design, operation, and accident management of nuclear
facilities, we may actually increase the probability of much larger
exposures from severe accidents.''
Response: The NRC disagrees with this comment. The operating
experience of nuclear facilities has not shown any relationship between
severe accident risk and radiation protection practices.
Comment: Several commenters expressed concern that the public's
fear of radiation exposure due to the NRC's continued use of the LNT
model could result in patients postponing or foregoing CT scans and
other diagnostic radiology procedures, thereby resulting in adverse
medical consequences to the patient. Other commenters asserted that the
use of LNT in the medical field can inhibit lifesaving processes that
require a higher radiation dose than what is currently acceptable or
can add to the cost of certain procedures, also inhibiting patients
from receiving important treatment.
Response: The NRC disagrees with this comment. Moreover, the NRC's
regulations do not apply to the decisions of a physician to prescribe a
certain diagnostic or therapeutic modality to treat a patient. The
physician's recommendation and the patient's decision to undergo a CT
scan are wholly informed by the professional judgement of the medical
provider and are therefore outside the scope of the NRC's regulatory
authority. The NRC does not regulate machine-generated radiation, which
is the type generated by the use of x-ray machines and CT devices.
Machine-generated radiation is regulated by the states, and as such,
any application of the LNT model to the NRC's radiation protection
requirements would not affect these medical uses.
Moreover, current evidence demonstrates that the use of radiation
producing devices in medical diagnostic tests and therapies in the
United States is increasing--all while LNT has been in place as the
underlying dose-response assumption for radiation protection. For
example, the NCRP reported that the average medical exposure in 2006
had increased substantially from the early 1980s, primarily due to the
increased use of CT, interventional fluoroscopy, and nuclear
medicine.\91\ With respect to CT, the NCRP stated that
``[t]echnological advances in CT and the ease of use of this technology
have led to many clinical applications that have increased the use of
CT at a rate of 8 to 15% per year for the last 7 to 10 years [prior to
2006].'' \92\ CT scanning further increased from 2006 to 2012.\93\ The
use of interventional fluoroscopy and nuclear medicine have also
similarly increased.\94\ The commenters' claims that patients are
postponing or foregoing radiology procedures is not supported. These
commenters did not present evidence to support the assertion that the
NRC's use of the LNT model results in adverse medical treatment
consequences.
---------------------------------------------------------------------------
\91\ NCRP, ``Ionizing Radiation Exposure of the Population of
the United States,'' Report No. 160 (2009), at 5.
\92\ Id., at 85 (alteration added).
\93\ Fred A. Mettler, MD, Professor Emeritus and Clinical
Professor, Department of Radiology, Mew Mexico School of Medicine,
presentation entitled ``Dose, Benefit, Risk and Safety'' at the 2018
Annual Meeting of the NCRP (March 5, 2018). Dr. Mettler's
presentation is expected to be published in the Health Physics
Journal in 2019.
\94\ Id., at 117 (the number of procedures in radiographic
fluoroscopy increased by 54% between 2002 and 2005) and at 195 (5%
annual growth in the number of nuclear-medicine procedures between
1995 and 2005).
---------------------------------------------------------------------------
Comment: One commenter stated that the summary of the petitioners'
position as described in the NRC's June 23, 2015, notice of docketing
(80 FR 35870), characterized the petitions inaccurately, by stating
that the petitioners wanted the NRC to amend the basis for radiation
protection under 10 CFR part 20 from the LNT model to the hormesis
model. The commenter expressed concerns that readers would be
negatively biased against the petitions due to this representation of
the petitioners' position.
Response: The NRC disagrees with this comment. In her petition, Dr.
Marcus requested that the NRC amend its radiation protection
regulations in 10 CFR part 20 to ``take radiation hormesis into
account.'' \95\ Dr. Marcus then made several specific recommendations,
including the complete removal of ALARA from the NRC's radiation
protection regulations; the end of ``differential doses to pregnant
women; embryos and fetuses, and children under 18 years of age''; and
an increase in radiation dose limits to members of the public so that
the public dose limit would be equal to the dose limits for
occupational workers. In her petition, Dr. Marcus states that the
removal of ALARA is ``not only harmless but may be hormetic,'' and in
requesting that ``[p]ublic doses should be raised to worker doses,''
asked ``[w]hy deprive the public of the benefits of low dose
radiation?'' \96\ In addition, Dr. Marcus referenced studies which she
argued suggest that low doses of radiation decrease cancer rates and
asserted ``[h]ormesis is a perfectly good alternative explanation'' for
such results.\97\ Similarly, in his petition, Mr. Miller recommends
that ``[p]ublic dose limits should be raised to match worker dose
limits, as these low doses may be hormetic,'' and that ``[l]ow-dose
limits for the public perpetuates radiophobia.'' \98\ Moreover, in its
June 23, 2015, Federal Register notice of docketing, the NRC stated
that the petitions were publicly-available and should be consulted for
additional information.\99\ Thus, the NRC concludes that it accurately
summarized the petitions in its June 23, 2015, Federal Register notice
of docketing.
---------------------------------------------------------------------------
\95\ Marcus petition (PRM-20-28), at 7.
\96\ Id.
\97\ Id., at 4.
\98\ Miller petition (PRM-20-29), at 6-7.
\99\ 80 FR, at 35872.
---------------------------------------------------------------------------
Comment: One commenter stated that a public education system should
be put in place to dispel fear of low-level radiation.
Response: The NRC considers this comment to be outside the scope of
the issues raised by the petitions, because
[[Page 45932]]
the establishment of a public education system to dispel fears of low-
level radiation is not a mission or responsibility of the NRC and is
beyond the NRC's statutory authority. The NRC supports communication
efforts to accurately convey the radiological risks associated with any
given regulated activity. The NRC, through its communication efforts,
engages stakeholders in order to foster transparency and communication
between the NRC and the public (e.g., through public meetings, public
comment on NRC rulemakings and guidance development, the NRC's public
website, and the NRC's use of social media).
Comment: The NRC received several comments requesting that the NRC
conduct research on topics raised by the petition.
Response: The NRC disagrees with these comments. The comments
requesting that the NRC engage in additional research is outside the
scope of the subject petitions. Other Federal agencies are charged with
conducting basic radiation research, such as the Department of Energy
and the National Institutes of Health.
Comments Supporting the Petitions--Assertions That the LNT Model Lacks
an Adequate Scientific Basis
Comment: Several commenters questioned the scientific basis of the
LNT model and asserted that it should no longer be the premise of the
NRC's radiological protection regulations.
Response: The NRC disagrees with these comments. The NRC's goal as
a regulatory agency is to protect both the public and occupational
workers from the radiological hazards associated with NRC-licensed
material, activities, and facilities. The NRC uses the LNT model to
establish radiation protection measures that quantify radiation
exposure and set regulatory limits. The premise of the LNT model is
that the long-term biological damage caused by ionizing radiation
(i.e., risk of cancer induction or adverse hereditary effects) is
directly proportional to the dose received by the human receptor. The
LNT model provides for a conservative, comprehensive radiation
protection scheme that protects individuals in all population
categories (male, female, adult, child, and infant) and exposure ranges
by reducing the risk from low-dose radiation exposure.
As described earlier in this document, the consensus among various
domestic and international authoritative scientific advisory bodies and
the three Federal agencies that submitted comments (NCI, NIOSH, and
EPA) is that the LNT model should remain the basis for the NRC's
radiological protection regulations. Similarly, the ACMUI recommends
that the NRC continue to use the LNT model. Based upon the external
organizations' recommendations, the ACMUI's recommendation, and its own
professional and technical judgment, the NRC has determined that the
LNT model continues to provide a sound basis for minimizing the risk of
unnecessary radiation exposure to both members of the public and
occupational workers.
Comment: One commenter noted that multiplying the LNT-based risk
coefficient by a population dose to derive a hypothetical number of
cancer deaths in no way shows, proves, or demonstrates that anyone is
getting cancer.
Response: The NRC disagrees with this comment. The petitions for
rulemaking request that the NRC amend 10 CFR part 20 to discontinue use
of the LNT model as the primary scientific basis for the agency's
radiation protection standards. The NRC does not use the LNT model for
deterministic mortality projections.
Comment: One commenter noted that the LNT model is flawed, because
it lacks timescale modeling to account for the differences between
getting a large dose over a long period of time as opposed to a large
dose in a short period of time.
Response: The NRC disagrees with this comment. The LNT model, as
applied by the NRC in its licensing and regulatory decisions,
effectively addresses the potential health impacts of any given dose
received either acutely or chronically.
Human epidemiologic studies have established that there is an
increased incidence of certain cancers associated with radiation
exposure at high doses and high dose rates (acute exposure). The
principal source of information for risk estimation is the Japanese
survivors of the atomic bombing of Hiroshima and Nagasaki in 1945, who
were exposed to a range of doses at a high dose rate.\100\ The NCRP
defines high dose rate as a dose rate above which recovery and repair
processes are unable to ameliorate the radiation damage.\101\ Both the
ICRP and NCRP estimate that the risk of death from radiation-induced
cancer resulting from an acute exposure is 10 x 10-2 per Sv
for a population of all ages.\102\ However, experimental results in
animals and other biological systems suggest that cancer induction from
acute exposures at low doses and involving low dose rates should be
less than that observed after high doses involving high dose
rates.\103\
---------------------------------------------------------------------------
\100\ NAS BEIR VII, at 6.
\101\ NCRP Report No. 116, at 60.
\102\ ICRP, ``1990 Recommendation of the International
Commission on Radiological Protection,'' Pub. No. 60 (1991), at 22;
NCRP Report No. 116, at 29.
\103\ ICRP Pub. No. 60, at 111.
---------------------------------------------------------------------------
If the radiation dose is received chronically (i.e., over a long
period of time), the biologic response differs because much of the
radiation damage is effectively and efficiently repaired.\104\ To
account for this difference in response to chronic low dose and low
dose rate radiation exposure as compared to high dose and high dose
rate radiation exposure, the ICRP and NCRP recommend, and the NRC has
adopted, adjusting the risk of death from radiation exposure using a
DDREF of two.\105\ The DDREF is assumed to apply whenever the absorbed
dose is less than 200 mSv (20 rem) and the dose rate is less than 100
mSv (10 rad) per hour.\106\ Consequently, the risk coefficient for
members of the public pertaining to low dose and low dose rate
radiation exposure is 5 x 10-2 per Sv. This risk coefficient
is further reduced to 4 x 10-2 per Sv for occupational
workers because this population excludes both the very young and
elderly who may be slightly more sensitive to radiation-induced
carcinogenesis.\107\ The risks of radiation exposure to occupational
workers are described further in Regulatory Guide (RG) 8.29,
``Instruction Concerning Risks from Occupational Radiation Exposure,''
Revision 1 (1996).
---------------------------------------------------------------------------
\104\ UNSCEAR, ``Non-stochastic effects of irradiation,'' Report
to the General Assembly, ANNEX J (1982) at 575.
\105\ ICRP Pub. No. 103, at 53; ICRP Pub. No. 60, at 18; NCRP
Report No. 116, at 29. Although the NRC has not formally adopted a
DDREF in regulation, it has relied upon a DDREF in computer
modeling. E.g., NUREG-2161, ``Consequence Study of a Beyond-Design-
Basis Earthquake Affecting the Spent Fuel Pool for a U.S. Mark I
Boiling Water Reactor,'' (September 2014) at 195 (incorporating
DDREF into computer modeling for offsite consequences of a
postulated spent fuel pool accident).
\106\ ICRP Pub. No. 60, at 19; NCRP Report No. 116, at 60.
\107\ ICRP Pub. No. 60, at 22; NCRP Report No. 116, at 29.
---------------------------------------------------------------------------
Although the appropriate value of the DDREF may depend on the
specific low or very low dose scenario,\108\ the use of a DDREF,
particularly one with a high value, does not mean that there are no
harmful health effects from low and very low doses of radiation. The
use of a DDREF also does not demonstrate the presence of a threshold
below which no permanent harmful effects will occur. The NRC staff
concludes that the use of
[[Page 45933]]
a DDREF in its dose calculations aligns with the LNT model.
---------------------------------------------------------------------------
\108\ For example, a DDREF value of ``1'' (no dose and dose rate
effect) is used for certain tissues such as the thyroid and a higher
value (e.g., a ``2'' or a ``3'') is used for other, less radio-
sensitive tissues.
---------------------------------------------------------------------------
Comment: Several commenters observed that mammals evolved in an
environment with a constant low dose of radiation. One commenter noted
that humans developed DNA repair mechanisms to compensate. This
commenter further stated that we experience far more DNA double strand
breaks during mitotic cell division than we do from exposure to
background radiation. As the biological mechanisms deployed to repair
DNA damage caused by mitotic cell division are well documented, the
commenter concludes that the rate of DNA damage that we can accommodate
is also documented. This commenter reasons that because the rate of
damage is substantially greater than zero, the LNT model cannot be
correct.
Response: The NRC disagrees with this comment. There is substantial
scientific uncertainty regarding the ability of the human body's immune
system, or other forms of adaptive response, to repair cells damaged by
ionizing radiation. According to the NCI comments, the available data
does not show that any immune or other adaptive response offsets the
carcinogenic damage caused by a given dose of ionizing radiation.\109\
NCI, in its comments, states that the ``repair of [DNA] double strand
breaks (DSBs) relies on a number of pathways,'' and that these pathways
are ``prone to errors,'' which may result in cell mutations, a fraction
of which may lead to cancer.\110\ NCI further notes that the
petitioners, and by extension, the commenter, do not reference data
which shows that various cohorts subjected to ``protracted radiation
exposures'' develop ``an increase in stable chromosome aberrations and
other markers of biological damage in the peripheral blood
lymphocytes.'' \111\ NCI states that such chromosome aberrations may
increase the risk of cancer, and concluded that ``there is little data
to suggest a threshold in dose, or possible hormetic (beneficial)
effects of low-dose radiation exposure.'' \112\
---------------------------------------------------------------------------
\109\ NCI 2015, at 3.
\110\ Id. (alteration added).
\111\ Id.
\112\ Id.
---------------------------------------------------------------------------
Comments Supporting the Petitions--Assertions That There Are No
Observable Adverse Effects From Background Radiation
Comment: Several commenters remarked that background levels of
ionizing radiation, which vary significantly around the world, have
never been demonstrated to be a health hazard to humans. Some
commenters also noted that in regions of the world such as Brazil or
India where background radiation levels are higher than normal,
epidemiological studies of large cohorts of subjects living in these
areas did not reveal excess cancers or diseases linked to radiation
exposure. On this basis, these commenters conclude that the LNT model
is based on a premise that is not supported by evidence.
Response: The NRC disagrees with these comments. The NRC notes
that, in general, the inability to observe an effect does not mean that
the effect has not occurred. These high background exposure studies are
epidemiological in nature. They cannot be used as quantitative
estimates of disease risk associated with the radiation exposure levels
found in the areas studied, because the studies lack sufficient
quantifiable evidence of the absence of cancer risk. As explained by
NCI there are limitations associated with reliance on epidemiological
studies in any effort to invalidate the LNT model. NCI noted that
``[c]ancer risks predicted by the LNT model are likely to be small at
low doses; so small as to be difficult to detect in the presence of
large numbers of cancers resulting from other causes.'' \113\ In this
regard, NCI further stated that ``because epidemiologic studies are
observational in nature and not controlled experiments, differences in
risks in exposed and unexposed [populations] may reflect differences in
life style factors such as smoking and may not necessarily result from
radiation exposure.'' \114\
---------------------------------------------------------------------------
\113\ Id., at 1.
\114\ Id.
---------------------------------------------------------------------------
In addition, the BEIR VII report prepared by NAS indicates that
studies of populations exposed to natural background radiation are
limited in their ability to define risk of disease in relation to
radiation dose. In discussing four studies of populations exposed to
natural background radiation, the BEIR VII Phase 2 report states:
These studies did not find higher disease rates in geographic
areas with high background levels of radiation exposure compared to
areas with lower background levels. However, these studies were
ecologic in design and utilized population-based measures of
exposure rather than individual estimates of radiation dose. Thus,
they cannot provide any quantitative estimates of disease risk
associated with the exposure levels found in the areas studied.\115\
---------------------------------------------------------------------------
\115\ NAS BEIR VII, at 228.
Also, the United Nations Scientific Committee on the Effects of
Atomic Radiation (UNSCEAR) has recently published a review of cancer
risk due to low dose rate radiation from environmental sources.\116\
UNSCEAR concluded that ``the results of the studies of cancer risk due
to radiation exposure at low dose rates from environmental radiation do
not provide strong evidence for materially lower risks per unit
exposure than in studies of high radiation doses and dose rates.''
\117\ In this regard, UNSCEAR noted that methodological improvements in
environmental studies are needed to overcome ``low statistical power,
dosimetric uncertainties, imperfections in control of confounding, and
any other biases'' to include ``under-ascertainment of cases (deaths or
diagnoses), inaccurate cancer diagnosis, imprecise dose assessment, and
residual confounding.'' \118\
---------------------------------------------------------------------------
\116\ UNSCEAR, ``Sources, Effects and Risks of Ionizing
Radiation, Annex B: Epidemiological studies of cancer risk due to
low-dose-rate radiation from environmental sources,'' Report to the
General Assembly with Scientific Annexes (2017) (UNSCEAR 2017
Report, Ann. B).
\117\ UNSCEAR 2017 Report, Ann. B, at 153.
\118\ Id., at 155.
---------------------------------------------------------------------------
Therefore, no direct inferences about radiation effects can be
drawn from studies where background radiation levels are higher than
normal.
Comments Supporting the Petitions--Objections to ALARA
Comment: One commenter asserted that current regulations are too
restrictive and focus too heavily on radiation protection, thus
creating a system that emphasizes compliance with ALARA at the expense
of ``basic lab safety,'' such as somebody falling and hitting their
head. The commenter posits that such accidents are far more likely than
receiving a ``fatal radiation dose.''
Response: The NRC disagrees with this comment. The NRC interprets
the commenter's use of the phrase ``basic lab safety'' as meaning
compliance with non-radiologic safety requirements. Non-radiologic
safety issues are the oversight responsibility of the Occupational
Safety and Health Administration (OSHA) and appropriate State and local
government agencies. Licensees are required and expected to comply with
both applicable NRC requirements as well as those of OSHA and the
pertinent State and local authorities. Moreover, licensees demonstrate
compliance with ALARA by such actions as establishing appropriate
procedures and engineering controls, providing the proper training
[[Page 45934]]
and equipment, restricting access to radiation areas, and ensuring
appropriate facility design. Therefore, ALARA practices should
complement and work in concert with ``basic lab safety,'' rather than
degrade it.
The ALARA definition and the associated regulatory requirement also
involve the concept of reasonableness, meaning that the licensee should
make ``every reasonable effort'' to implement ALARA measures and should
use procedures and engineering controls based upon sound radiation
protection principles to achieve ALARA, to the ``extent practical.''
\119\ In addition, NRC guidance indicates that non-radiological hazards
should be considered in determining appropriate ALARA measures. For
example, RG 8.8, ``Information Relevant to Ensuring That Occupational
Radiation Exposures at Nuclear Power Stations Will Be as Low as Is
Reasonable Achievable,'' states that ``a comprehensive consideration of
risks and benefits will include risks from nonradiological hazards. An
action taken to reduce radiation risks should not result in a
significantly larger risk from other hazards.'' \120\ Similarly, RG
8.10, ``Operating Philosophy for Maintaining Occupational and Public
Radiation Exposures as Low as Is Reasonably Achievable,'' states that
``the decision to implement measures to reduce occupational radiation
doses should be weighed against the risk of any other occupational
hazards in the workplace, to minimize the total risk to the worker's
health and safety.'' \121\
---------------------------------------------------------------------------
\119\ 10 CFR 20.1003 and 10 CFR 20.1101(b).
\120\ RG 8.8, Rev. 3, at 2.
\121\ RG 8.10, Rev. 2, at 5.
---------------------------------------------------------------------------
Finally, the commenter did not provide any support for the
assertion that a licensee's compliance with ALARA or other NRC
requirements based upon the LNT model undermines or otherwise impedes a
licensee's ability to comply with non-radiologic safety requirements.
Comments: Several commenters objected to the use of the ALARA
concept as a regulatory requirement by the NRC. Many of these
commenters asserted that the implementation of ALARA results in
excessive costs to licensees and as such, inhibits potential growth and
innovation. Some commenters also asserted that ALARA does not strike
the appropriate balance between safety and economy. Virtually all of
these commenters requested the removal of the ALARA requirement in
order to reduce costs.
Response: The NRC disagrees with these comments. The NRC
regulations define ALARA as ``making every reasonable effort to
maintain exposures to radiation as far below the dose limits in this
part as is practical consistent with the purpose for which the licensed
activity is undertaken.'' \122\ ALARA takes into account the following,
in relation to the utilization of nuclear energy and licensed materials
in the public interest: (1) The state of technology, (2) the economics
of improvements in relation to the state of technology, (3) the
economics of improvements in relation to benefits to the public health
and safety, and (4) other societal and socioeconomic
considerations.\123\ The NRC requires that its licensees ``use, to the
extent practical, procedures and engineering controls based upon sound
radiation protection principles to achieve occupational doses and doses
to members of the public that are [ALARA].'' \124\ Furthermore, the
NRC's 1991 rule stated that ``the ALARA concept is intended to be an
operating principle rather than an absolute minimization of
exposures.'' \125\
---------------------------------------------------------------------------
\122\ 10 CFR 20.1003.
\123\ Id.
\124\ 10 CFR 20.1101(b).
\125\ 56 FR at 23366.
---------------------------------------------------------------------------
The regulatory language of the ALARA definition sets out the
considerations in making ALARA determinations, several of which include
the consideration of economic factors.\126\ The NRC guidance states
that `` `[r]easonably achievable' is judged by considering the state of
technology and the economics of improvements in relation to all the
benefits from these improvements.'' \127\ In general, the NRC
determines compliance with the ALARA requirement based on whether the
licensee has incorporated measures to track and, if necessary, to
reduce exposures; not whether exposures and doses represent an absolute
minimum or whether the licensee has used all possible methods to reduce
exposures. Furthermore, the level of effort expended on radiation
protection programs, including compliance with the ALARA concept,
should reflect the magnitude of the potential exposures--both the
magnitude of average and maximum individual doses and, in facilities
with large numbers of employees, collective (population) doses.\128\
Thus, the size of a licensee's radiation protection program should be
commensurate with the scope and extent of the licensed activities. For
example, a large organization, such as a nuclear power reactor
licensee, would be expected to have a considerably larger and more
extensive radiation protection program than a smaller organization that
may maintain lower activity sealed sources.
---------------------------------------------------------------------------
\126\ 10 CFR 20.1003 (``the economics of improvements in
relation to the state of technology,'' ``the economics of
improvements in relation to benefits to the public health and
safety,'' and ``other societal and socioeconomic considerations'').
\127\ RG 8.8, Rev. 3, at 2.
\128\ Id.
---------------------------------------------------------------------------
In addition, ALARA is achieved by implementing such fundamental
measures as effective planning, training of the appropriate personnel,
provision of appropriate equipment (e.g., dosimeters), controlling
access to radiation areas, installation of radiation monitoring
systems, and preparing appropriate facility designs.\129\ The regulated
community has had decades of operational experience in implementing
ALARA measures, and it is likely that most costs of ALARA compliance
have long since been optimized. Moreover, the NRC considers many of
these measures to be simply the implementation of sound operating
practices. Finally, other than their general assertions, the commenters
have not provided any substantive evidence demonstrating that the ALARA
concept or the LNT model inhibits innovation or growth. The NRC has
determined that current ALARA requirements are consistent with the LNT
model of radiation protection and reasonably account for economic
considerations.
---------------------------------------------------------------------------
\129\ RG 8.10, Rev. 2, at 5; see also RG 8.8, Rev. 3.
---------------------------------------------------------------------------
Comments Supporting the Petitions--Assertion That the NRC Relies on the
LNT Model as a Result of Political Pressure or Bias
Comment: Several commenters stated that the LNT model continues to
remain relevant as a regulatory framework only because of political
pressure or ideological or scientific bias.
Response: The NRC disagrees with this comment. The NRC is an
independent regulatory agency that establishes its radiation protection
regulations based, in part, on the recommendations of domestic and
international authoritative scientific advisory bodies such as the
ICRP, the NAS, and the NCRP. As described previously in this document,
three other Federal agencies and the ACMUI recommend that the LNT model
remain the basis for the NRC's radiation protection regulations. The
commenters have not provided any substantive support for their
assertion that political pressure or bias is motivating the NRC to
continue to rely upon the LNT model. The NRC continues to conclude
that, in the absence of convincing evidence that there is a dose
threshold or that low
[[Page 45935]]
levels of radiation are beneficial, the LNT model remains a prudent and
conservative basis for the NRC's radiation protection regulations.
V. Availability of Documents
The following table provides information about materials referenced
in this notification. The ADDRESSES section of this notification
provides additional information about how to access ADAMS.
------------------------------------------------------------------------
ADAMS accession
No. or Federal
Date Document Register
citation
------------------------------------------------------------------------
Submitted Petitions
------------------------------------------------------------------------
February 9, 2015.............. Petition for ML15051A503.
Rulemaking (PRM-20-
28).
February 13, 2015............. Petition for ML15057A349.
Rulemaking (PRM-20-
29).
February 24, 2015............. Petition for ML15075A200.
Rulemaking (PRM-20-
30).
------------------------------------------------------------------------
Federal Register Notifications
------------------------------------------------------------------------
June 23, 2015................. 10 CFR part 20--Linear 80 FR 35870.
no-Threshold Model
and Standards for
Protection Against
Radiation--Notice of
Docketing and Request
for Comment (PRM-20-
28, PRM-20-29, and
PRM-20-30).
August 21, 2015............... 10 CFR part 20--Linear 80 FR 50804.
no-Threshold Model
and Standards for
Protection Against
Radiation--Notice of
Docketing and Request
for Comment;
Extension of Comment
Period (PRM-20-28,
PRM-20-29, and PRM-20-
30).
September 8, 2015............. Advisory Committee on 80 FR 53896.
the Medical Uses of
Isotopes: Meeting
Notice.
May 21, 1991.................. 10 CFR part 20, 56 FR 23360.
``Radiation
Protection,'' Advance
Notice of Proposed
Rulemaking; Request
for Comments.
January 27, 1987.............. Federal Radiation 52 FR 2822.
Protection Guidance
for Occupational
Exposure.
------------------------------------------------------------------------
Federal Regulations
------------------------------------------------------------------------
1991.......................... 10 CFR part 20, N/A.
``Standards for
Protection Against
Radiation''.
2006.......................... NAS BEIR VII, ``Health N/A.
Risks from Exposure
to Low Levels of
Ionizing Radiation''.
1946.......................... U.S. Code: Title 42, N/A.
Chapter 23,
``Development and
Control of Atomic
Energy''.
------------------------------------------------------------------------
National and International Publications
------------------------------------------------------------------------
2005.......................... ICRP Publication 99, N/A.
``Low-dose
Extrapolation of
Radiation-related
Cancer Risk''.
1977.......................... ICRP Publication 26, N/A.
``Recommendations of
the International
Commission on
Radiological
Protection''.
1993.......................... NCRP Report No. 116, N/A.
``Limitation of
Exposure to Ionizing
Radiation''.
2001.......................... NCRP Report No. 136, N/A.
``Evaluation of the
Linear-Nonthreshold
Dose-Response Model
for Ionizing
Radiation''.
2005.......................... Academy of Sciences N/A.
and National Academy
of Medicine (France),
``Dose-Effect
Relationships and
Estimation of the
Carcinogenic Effects
of Low Doses of
Ionizing Radiation''.
August 1998................... IAEA, ``Measures to N/A.
Strengthen
International Co-
Operation in Nuclear,
Radiation and Waste
Safety, Nuclear
Safety Review for the
Year 1997''.
2014.......................... IAEA, ``Radiation N/A.
Protection and Safety
of Radiation Sources:
International Basic
Safety Standards,
General Safety
Requirements Part 3''.
April 24, 2018................ NCRP Commentary 27, N/A.
``Implications of
Recent Epidemiologic
Studies for the
Linear Nonthreshold
Model and Radiation
Protection''.
2009.......................... NCRP Report No. 160, N/A.
``Ionizing Radiation
Exposure of the
Population of the
United States''.
1991.......................... ICRP Publication 60, N/A.
``1990
Recommendations of
the International
Commission on
Radiological
Protection''.
2007.......................... ICRP Publication No. N/A.
103, ``The 2007
Recommendations of
the International
Commission on
Radiological
Protection''.
------------------------------------------------------------------------
Other Reference Documents
------------------------------------------------------------------------
July 1993..................... Health Physics N/A.
Society, Position
Statement PS008-2,
``Uncertainty in Risk
Assessment,''
(Revised April 1995,
February 2013).
2017.......................... Dr. John D. Boice, N/A.
Jr., ``The linear
nonthreshold (LNT)
model as used in
radiation protection:
An NCRP update,''
International ournal
of Radiation Biology,
Vol. 93, No. 10.
June 2015..................... K. Leuraud et al., N/A.
``Ionising Radiation
and Risk of Death
from Leukaemia and
Lymphoma in Radiation-
monitored Workers
(INWORKS): An
International Cohort
Study, Lancet
Haematology, Vol. 2''.
October 28, 2015.............. ACMUI, ``Final Report ML15310A418.
on the Hormesis/
Linear No-Threshold
Petitions''.
[[Page 45936]]
August 2016................... RG 8.10, ``Operating ML16105A136.
Philosophy for
Maintaining
Occupational and
Public Radiation
Exposures As Low As
Is Reasonably
Achievable,'' Rev. 2.
June 1978..................... RG 8.8, ``Information ML003739549.
Relevant to Ensuring
that Occupational
Radiation Exposures
at Nuclear Power
Stations Will Be as
Low as Is Reasonably
Achievable,'' Rev. 3.
September 2014................ NUREG-2161, ML14255A365.
``Consequence Study
of a Beyond-Design-
Basis Earthquake
Affecting the Spent
Fuel Pool for a U.S.
Mark I Boiling Water
Reactor''.
2017.......................... UNSCEAR, ``Sources, N/A.
Effects and Risks of
Ionizing Radiation,
Annex B:
Epidemiological
studies of cancer
risk due to low-dose-
rate radiation from
environmental
sources''.
1996.......................... RG 8.29, ``Instruction ML003739438.
Concerning Risks from
Occupational
Radiation Exposure''
Rev. 1.
------------------------------------------------------------------------
VI. Conclusion
The NRC reviewed the petitioners' requests, as well as public
comments received on the petitions. For the reasons cited in this
document, the NRC is denying the three PRMs, specifically PRM-20-28,
PRM-20-29, and PRM-20-30, in their entirety. Given the current state of
scientific knowledge, the NRC has determined that the LNT model
continues to be an appropriate basis for its radiation protection
regulatory framework. Thus, the NRC's current radiation protection
regulations provide for the adequate protection of human health and
safety, and as such, changes to 10 CFR part 20 are not warranted at
this time.
Dated: August 11, 2021.
For the Nuclear Regulatory Commission.
Annette L. Vietti-Cook,
Secretary of the Commission.
[FR Doc. 2021-17475 Filed 8-16-21; 8:45 am]
BILLING CODE 7590-01-P