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Rule2022-27522

Reconsideration of the 2020 National Emission Standards for Hazardous Air Pollutants: Miscellaneous Organic Chemical Manufacturing Residual Risk and Technology Review

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Published

December 21, 2022

Effective

December 21, 2022

Issuing agencies

Environmental Protection Agency

Abstract

On August 12, 2020, the U.S. Environmental Protection Agency (EPA) published the final risk and technology review (RTR) for the Miscellaneous Organic Chemical Manufacturing NESHAP (2020 MON final rule) pursuant to Clean Air Act (CAA). Subsequently, the EPA received and granted petitions for reconsideration on two issues, specifically, on the use of the EPA's IRIS value for ethylene oxide in assessing cancer risk for the source category, and the use of the Texas Commission on Environmental Quality's (TCEQ's) risk value for ethylene oxide as an alternative risk value to the EPA's IRIS value for purposes of evaluating risk as part of the CAA residual risk review. On February 4, 2022, the EPA proposed the Reconsideration of the 2020 National Emission Standards for Hazardous Air Pollutants (NESHAP): Miscellaneous Organic Chemical Manufacturing Residual Risk and Technology Review to address these two issues and request public comment. This action finalizes the EPA's decision to use the IRIS value for ethylene oxide in the risk assessment for the 2020 MON final rule and our decision to reject the use of the TCEQ's risk value for ethylene oxide as an alternative risk value to the EPA's IRIS value. As such, in this final action, EPA is making no changes to the risk assessment or related regulatory text for the miscellaneous organic chemical manufacturing source category.

Full Text

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<title>Federal Register, Volume 87 Issue 244 (Wednesday, December 21, 2022)</title>
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[Federal Register Volume 87, Number 244 (Wednesday, December 21, 2022)]
[Rules and Regulations]
[Pages 77985-77995]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2022-27522]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[EPA-HQ-OAR-2018-0746; FRL-6494.1-02-OAR]
RIN 2060-AV54

Reconsideration of the 2020 National Emission Standards for
Hazardous Air Pollutants: Miscellaneous Organic Chemical Manufacturing
Residual Risk and Technology Review

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final action; reconsideration of the final rule.

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SUMMARY: On August 12, 2020, the U.S. Environmental Protection Agency
(EPA) published the final risk and technology review (RTR) for the
Miscellaneous Organic Chemical Manufacturing NESHAP (2020 MON final
rule) pursuant to Clean Air Act (CAA).

[[Page 77986]]

Subsequently, the EPA received and granted petitions for
reconsideration on two issues, specifically, on the use of the EPA's
IRIS value for ethylene oxide in assessing cancer risk for the source
category, and the use of the Texas Commission on Environmental
Quality's (TCEQ's) risk value for ethylene oxide as an alternative risk
value to the EPA's IRIS value for purposes of evaluating risk as part
of the CAA residual risk review. On February 4, 2022, the EPA proposed
the Reconsideration of the 2020 National Emission Standards for
Hazardous Air Pollutants (NESHAP): Miscellaneous Organic Chemical
Manufacturing Residual Risk and Technology Review to address these two
issues and request public comment. This action finalizes the EPA's
decision to use the IRIS value for ethylene oxide in the risk
assessment for the 2020 MON final rule and our decision to reject the
use of the TCEQ's risk value for ethylene oxide as an alternative risk
value to the EPA's IRIS value. As such, in this final action, EPA is
making no changes to the risk assessment or related regulatory text for
the miscellaneous organic chemical manufacturing source category.

DATES: This final action is effective on December 21, 2022.

ADDRESSES: The U.S. Environmental Protection Agency (EPA) has
established a docket for this action under Docket ID No. EPA-HQ-OAR-
2018-0746. All documents in the docket are listed on the <a href="https://www.regulations.gov/">https://www.regulations.gov/</a> website. Although listed, some information is not
publicly available, e.g., Confidential Business Information or other
information whose disclosure is restricted by statute. Certain other
material, such as copyrighted material, is not placed on the internet
and will be publicly available only in hard copy form. Publicly
available docket materials are available either electronically through
<a href="https://www.regulations.gov/">https://www.regulations.gov/</a>, or in hard copy at the EPA Docket Center,
WJC West Building, Room Number 3334, 1301 Constitution Ave. NW,
Washington, DC. The Public Reading Room hours of operation are 8:30
a.m. to 4:30 p.m. Eastern Standard Time (EST), Monday through Friday.
The telephone number for the Public Reading Room is (202) 566-1744, and
the telephone number for the EPA Docket Center is (202) 566-1742.

FOR FURTHER INFORMATION CONTACT: For questions about this final action,
contact Ms. Susan Paret, Sector Policies and Programs Division (E-120
C), Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina 27711;
telephone number: (919) 541-5516; and email address:
<a href="/cdn-cgi/l/email-protection#2454455641500a575157454a644154450a434b52">[email&#160;protected]</a>. For specific information regarding these
reconsideration decisions, contact Amy Vasu, Health and Environmental
Impacts Division (C539-02), Office of Air Quality Planning and
Standards, U.S. Environmental Protection Agency, Research Triangle
Park, North Carolina 27711; telephone number: (919) 541-0107; and email
address: <a href="/cdn-cgi/l/email-protection#661007151348070b1f2603160748010910">[email&#160;protected]</a>. For information about the applicability of
the NESHAP to a particular entity, contact John Cox, Office of
Enforcement and Compliance Assurance, U.S. Environmental Protection
Agency, WJC South Building, 1200 Pennsylvania Ave. NW, Washington, DC
20460; telephone number: (202) 564-1395; and email address:
<a href="/cdn-cgi/l/email-protection#ef8c8097c185808781af8a9f8ec1888099">[email&#160;protected]</a>.

SUPPLEMENTARY INFORMATION: Preamble acronyms and abbreviations. We use
multiple acronyms and terms in this preamble. While this list may not
be exhaustive, to ease the reading of this preamble and for reference
purposes, the EPA defines the following terms and acronyms here:

CAA Clean Air Act
CRA Congressional Review Act
EtO ethylene oxide
HAP hazardous air pollutants(s)
IRIS Integrated Risk Information System
MACT maximum achievable control technology
MCPU miscellaneous organic chemical manufacturing process unit
MIR maximum individual risk
MON Miscellaneous Organic Chemical Manufacturing NESHAP
NESHAP national emission standards for hazardous air pollutants
NIOSH National Institute for Occupational Safety and Health
NTTAA National Technology Transfer and Advancement Act
PRA Paperwork Reduction Act
RFA Regulatory Flexibility Act
RTR risk and technology review
SAB Science Advisory Board
SSM startup, shutdown, and malfunction
UMRA Unfunded Mandates Reform Act
URE unit risk estimate

Background information. On February 4, 2022, the EPA proposed the
Reconsideration of the 2020 National Emission Standards for Hazardous
Air Pollutants (NESHAP): Miscellaneous Organic Chemical Manufacturing
Residual Risk and Technology Review (87 FR 6466). In this action, we
are finalizing decisions on the two issues for which we granted
reconsideration. We summarize specific comment topics received on our
proposed action and our responses central to our rationale for the
decisions in this action. A summary of all public comments on the
proposal and the EPA's responses to those comments is available in
Summary of Public Comments and Responses for the Reconsideration of the
2020 National Emission Standards for Hazardous Air Pollutants:
Miscellaneous Organic Chemical Manufacturing Residual Risk and
Technology Review, Docket ID No. EPA-HQ-OAR-2018-0746.
Organization of this document. The information in this preamble is
organized as follows:

I. General Information
A. What is the source of authority for this reconsideration
action?
B. Does this action apply to me?
C. Where can I get a copy of this document and other related
information?
D. Judicial Review and Administrative Reconsideration
II. Background Information
III. Final Action
A. Issue 1: Use of the EPA's IRIS Value for Ethylene Oxide in
Assessing Cancer Risk for the Source Category
B. Issue 2: Use of the TCEQ Risk Value for Ethylene Oxide in
Assessing Cancer Risk for the Source Category
IV. Summary of Cost, Environmental, and Economic Impacts and
Additional Analyses Conducted
A. What are the affected facilities?
B. What are the air quality impacts?
C. What are the cost impacts?
D. What are the economic impacts?
E. What are the benefits?
F. What analysis of environmental justice did we conduct?
G. What analysis of children's environmental health did we
conduct?
V. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review and
Executive Order 13563: Improving Regulation and Regulatory Review
B. Paperwork Reduction Act (PRA)
C. Regulatory Flexibility Act (RFA)
D. Unfunded Mandates Reform Act (UMRA)
E. Executive Order 13132: Federalism
F. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
G. Executive Order 13045: Protection of Children From
Environmental Health Risks and Safety Risks
H. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
I. National Technology Transfer and Advancement Act (NTTAA)
J. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations
K. Congressional Review Act (CRA)

I. General Information

A. What is the source of authority for this reconsideration action?

The source of authority for this action is provided by sections 112
and

[[Page 77987]]

307(d)(7)(B) of the Clean Air Act (CAA) (42 U.S.C. 7412 and
7607(d)(7)(B)).

B. Does this action apply to me?

Regulated entities. Categories and entities potentially regulated
by this action are shown in Table 1 of this preamble.

Table 1--NESHAP and Industrial Source Categories Affected by This Final
Action
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NESHAP and source category NAICS \1\ code
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40 CFR part 63, subpart FFFF, 3251, 3252, 3253, 3254, 3255,
Miscellaneous Organic Chemical 3256, and 3259, with several
Manufacturing. exceptions.
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\1\ North American Industry Classification System.

Table 1 of this preamble is not intended to be exhaustive, but
rather to provide a guide for readers regarding entities likely to be
affected by the final action for the source category listed. To
determine whether your facility is affected, you should examine the
applicability criteria in the appropriate NESHAP. If you have any
questions regarding the applicability of any aspect of this NESHAP,
please contact the appropriate person listed in the preceding FOR
FURTHER INFORMATION CONTACT section of this preamble.

C. Where can I get a copy of this document and other related
information?

In addition to being available in the docket, an electronic copy of
this final action will also be available on the internet. Following
signature by the EPA Administrator, the EPA will post a copy of this
final action at: <a href="https://www.epa.gov/stationary-sources-air-pollution/miscellaneous-organic-chemical-manufacturing-national-emission">https://www.epa.gov/stationary-sources-air-pollution/miscellaneous-organic-chemical-manufacturing-national-emission</a>.
Following publication in the Federal Register, the EPA will post the
Federal Register version and key technical documents at this same
website.
Copies of all oral and written comments received on the proposed
rulemaking (Reconsideration of the 2020 National Emission Standards for
Hazardous Air Pollutants (NESHAP): Miscellaneous Organic Chemical
Manufacturing Residual Risk and Technology Review (87 FR 6466; February
4, 2022) are available at the EPA Docket Center Public Reading Room.
Comments are also available electronically through <a href="https://www.regulations.gov/">https://www.regulations.gov/</a> by searching Docket ID No. EPA-HQ-OAR-2018-0746.
Additional information is available on the RTR website at <a href="https://www.epa.gov/stationary-sources-air-pollution/risk-and-technology-review-national-emissions-standards-hazardous">https://www.epa.gov/stationary-sources-air-pollution/risk-and-technology-review-national-emissions-standards-hazardous</a>. This information
includes an overview of the RTR program and links to project websites
for the RTR Source categories.

D. Judicial Review and Administrative Reconsideration

Under Clean Air Act (CAA) section 307(b)(1), judicial review of
this final action is available only by filing a petition for review in
the United States Court of Appeals for the District of Columbia Circuit
by February 21, 2023. Under CAA section 307(b)(2), the requirements
established by this final action may not be challenged separately in
any civil or criminal proceedings brought by the EPA to enforce the
requirements.
Section 307(d)(7)(B) of the CAA further provides that only an
objection to a rule or procedure which was raised with reasonable
specificity during the period for public comment (including any public
hearing) may be raised during judicial review. This section also
provides a mechanism for the EPA to reconsider the rule if the person
raising an objection can demonstrate to the Administrator that it was
impracticable to raise such objection within the period for public
comment or if the grounds for such objection arose after the period for
public comment (but within the time specified for judicial review) and
if such objection is of central relevance to the outcome of the rule.
Any person seeking to make such a demonstration should submit a
Petition for Reconsideration to the Office of the Administrator, U.S.
EPA, Room 3000, WJC South Building, 1200 Pennsylvania Ave. NW,
Washington, DC 20460, with a copy to both the person(s) listed in the
preceding FOR FURTHER INFORMATION CONTACT section, and the Associate
General Counsel for the Air and Radiation Law Office, Office of General
Counsel (Mail Code 2344A), U.S. EPA, 1200 Pennsylvania Ave. NW,
Washington, DC 20460.

II. Background Information

The EPA promulgated the Miscellaneous Organic Chemical
Manufacturing NESHAP (MON) on November 10, 2003 (68 FR 63852), and
further amended the MON on July 1, 2005 (70 FR 38562), and July 14,
2006 (71 FR 40316). The standards are codified at 40 CFR part 63,
subpart FFFF. The MON regulates HAP emissions from miscellaneous
organic chemical manufacturing process units (MCPUs) located at major
sources. An MCPU includes equipment necessary to operate a
miscellaneous organic chemical manufacturing process, as defined in 40
CFR 63.2550(i), and must meet the following criteria: (1) it
manufactures any material or family of materials described in 40 CFR
63.2435(b)(1); (2) it processes, uses, or generates any of the organic
HAP described in 40 CFR 63.2435(b)(2); and, (3) except for certain
process vents that are part of a chemical manufacturing process unit,
as identified in 40 CFR 63.100(j)(4), the MCPU is not an affected
source or part of an affected source under another subpart of 40 CFR
part 63. An MCPU also includes any assigned storage tanks and transfer
racks; equipment in open systems that is used to convey or store water
having the same concentration and flow characteristics as wastewater;
and components such as pumps, compressors, agitators, pressure relief
devices (PRDs), sampling connection systems, open-ended valves or
lines, valves, connectors, and instrumentation systems that are used to
manufacture any material or family of materials described in 40 CFR
63.2435(b)(1). Sources of HAP emissions regulated by the MON include
the following: process vents, storage tanks, transfer racks, equipment
leaks, wastewater streams, and heat exchange systems.
The EPA conducted an RTR for the MON, pursuant to CAA sections
112(d)(6) and (f)(2), publishing proposed amendments on December 17,
2019 (84 FR 69182). As of November 6, 2018, the Source category covered
by this MACT standard included 201 facilities, herein referred to as
``MON facilities.'' This facility population count was developed using
methods described in section II.C of the RTR proposal preamble (84 FR
69182, 69186-87). A complete list of known MON facilities is available
in Appendix 1 of the document, Residual Risk

[[Page 77988]]

Assessment for the Miscellaneous Organic Chemical Manufacturing Source
Category in Support of the 2019 Risk and Technology Review Proposed
Rule, which is available in the docket for this rulemaking (see Docket
Item No. EPA-HQ-OAR-2018-0746-0011). After soliciting and considering
public comments, the EPA took final action in 2020 (85 FR 49084; August
12, 2020). The 2020 MON final rule included revisions to the NESHAP
pursuant to the technology review for equipment leaks and heat exchange
systems, and revisions pursuant to the risk review to specifically
address ethylene oxide emissions from storage tanks, process vents, and
equipment leaks. In addition, the 2020 MON final rule corrected and
clarified regulatory provisions related to emissions during periods of
startup, shutdown, and malfunction (SSM), including removing general
exemptions for periods of SSM, adding work practice standards for
periods of SSM where appropriate, and clarifying regulatory provisions
for certain vent control bypasses. The final action also added
monitoring and operational requirements for flares that control
ethylene oxide emissions and flares used to control emissions from
processes that produce olefins and polyolefins, added provisions for
electronic reporting of performance test results and other reports, and
included other technical corrections to improve consistency and
clarity.
In the 2020 MON final rule's risk assessment,\1\ the Agency
calculated cancer risks associated with emissions of ethylene oxide
using the EPA's IRIS value for that pollutant,2 3 and the
risk review included a determination that the risks for this source
category under the current Maximum Achievable Control Technology (MACT)
provisions were unacceptable due to ethylene oxide emissions. When
risks are unacceptable, the EPA must determine the emissions standards
necessary to reduce risk to an acceptable level. As such, the EPA
promulgated final amendments to the MON pursuant to CAA section
112(f)(2) that require control of ethylene oxide emissions for process
vents, storage tanks, and equipment in ethylene oxide service. The 2020
MON final rule reduced risks to an acceptable level that also provides
an ample margin of safety to protect public health.
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\1\ Residual Risk Assessment for the Miscellaneous Organic
Chemical Manufacturing Source Category in Support of the 2020 Risk
and Technology Review: Final Rule, August 2020. Available at:
<a href="https://www.regulations.gov/document/EPA-HQ-OAR-2018-0746-0189">https://www.regulations.gov/document/EPA-HQ-OAR-2018-0746-0189</a>.
\2\ The IRIS value is, specifically, the inhalation unit risk
estimate (URE) for ethylene oxide. The URE is the upper bound
additional lifetime cancer risk estimated to result from continuous
(24 hours/day) lifetime (70 years) exposure to ethylene oxide at a
concentration of 1 [mu]g/m\3\ in air. Because ethylene oxide is
mutagenic (i.e., damages DNA), an age-dependent adjustment factor
was applied to the URE to account for childhood exposures.
Therefore, the IRIS value used in the risk assessment is the age-
adjusted inhalation URE for ethylene oxide, which is 0.005 per
[mu]g/m\3\.
\3\ U.S. EPA. Evaluation of the Inhalation Carcinogenicity of
Ethylene Oxide (CASRN 75-21-8) In Support of Summary Information on
the Integrated Risk Information System (IRIS). December 2016. EPA/
635/R-16/350Fa. Available at: <a href="https://cfpub.epa.gov/ncea/iris/iris_documents/documents/toxreviews/1025tr.pdf">https://cfpub.epa.gov/ncea/iris/iris_documents/documents/toxreviews/1025tr.pdf</a> and in the docket for
this rulemaking (see Docket ID No. EPA-HQ-OAR-2018-0746).
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The EPA received comments from TCEQ during the public comment
period that included their draft cancer dose-response assessment for
ethylene oxide. The final rule preamble stated that ``the EPA remains
open to new and updated scientific information'' and new dose-response
values, such as the dose-response value then being developed by the
TCEQ (85 FR at 49098). However, by the close of the public comment
period for the proposed rulemaking, on March 19, 2020, the TCEQ dose-
response value had not yet been finalized and could not be considered
in the final action.
Following promulgation of the 2020 MON final rule, the EPA received
five separate petitions for reconsideration from four unique
petitioners. The EPA received two petitions from the American Chemistry
Council (ACC) (one petition dated October 2020, one dated December
2020), one from the TCEQ (dated October 2020), one from Squire Patton
Boggs (US) LLP (submitted on behalf of Huntsman Petrochemical, LLC)
(dated October 2020), and one from Earthjustice (submitted on behalf of
RISE St. James, Louisiana Bucket Brigade, Louisiana Environmental
Action Network, Texas Environmental Justice Advocacy Services
(t.e.j.a.s.), Air Alliance Houston, Ohio Valley Environmental
Coalition, Blue Ridge Environmental Defense League, Inc., Environmental
Justice Health Alliance for Chemical Policy Reform, Sierra Club,
Environmental Integrity Project, and Union of Concerned Scientists)
(dated October 2020). Copies of the petitions are available in the
docket for this rulemaking (see Docket ID Nos. EPA-HQ-OAR-2018-0746-
0259, EPA-HQ-OAR-2018-0746-0260, EPA-HQ-OAR-2018-0746-0261, EPA-HQ-OAR-
2018-0746-0262, and EPA-HQ-OAR-2018-0746-0263).
Three petitioners (ACC, TCEQ, and Huntsman Petrochemical, LLC)
requested that EPA reconsider the rule to reassess the risk assessment
for the 2020 MON final rule using the TCEQ's alternative risk value for
ethylene oxide instead of the EPA's IRIS value for ethylene oxide.
These three petitioners further argued that the EPA's IRIS value for
ethylene oxide is flawed, citing their disagreement with the EPA Office
of Research and Development's model selection and inclusion of breast
cancer data in the IRIS assessment. In their petitions, ACC and
Earthjustice also raised other issues unrelated to the use of the IRIS
value or the TCEQ value for assessing risk from ethylene oxide
emissions.
On June 22, 2021, the EPA sent letters to all of the petitioners
informing them that: (1) the EPA was granting reconsideration requests
on two specific issues (described in the next paragraph), (2) the EPA
intended to issue a Federal Register document initiating a document and
comment rulemaking on the issues for which the Agency granted
reconsideration, and (3) the EPA was continuing to review the other
issues in the petitions for reconsideration and may choose to initiate
reconsideration of additional issues in the future. Copies of the
letters to petitioners are available in the docket for this rulemaking
(see Docket ID Nos. EPA-HQ-OAR-2018-0746-0249, EPA-HQ-OAR-2018-0746-
0250, EPA-HQ-OAR-2018-0746-0251, and EPA-HQ-OAR-2018-0746-0252).
On February 4, 2022 (87 FR 6466), pursuant to CAA section
307(d)(7)(B), the EPA proposed to take comment on the issues for which
reconsideration was granted in the June 22, 2021 letters. In the
proposal, the EPA solicited public comment on the following aspects of
the 2020 MON final rule: (1) the use of the EPA's IRIS value for
ethylene oxide in assessing cancer risk for the Source category, and
(2) the use of the TCEQ risk value for ethylene oxide as an alternative
risk value to the EPA's IRIS value for purposes of evaluating risk
under CAA section 112(f)(2). Reconsideration was granted on these two
topics on the following bases: the TCEQ risk value for ethylene oxide
was finalized after the comment period for the proposed MON rulemaking
closed, and the 2020 MON final rule preamble stated that the EPA
remains open to new and updated scientific information, such as the
TCEQ value; and because the risk posed by ethylene oxide is of central
relevance to the EPA's determination that the risks from sources in the
Miscellaneous Organic Chemical Manufacturing Source category remaining
after imposition of the then-current CAA section 112(d)(2) MACT
standards were unacceptable and that more stringent standards are
required.

[[Page 77989]]

Note that, for this reconsideration action, the EPA sought comment
only on the two issues subject to mandatory reconsideration described
in the proposal preamble for this reconsideration (87 FR 6466; February
4, 2022). Because the criteria for mandatory reconsideration under CAA
section 307(d)(7)(B) have been satisfied, the Agency is publishing this
final reconsideration action in the Federal Register.

III. Final Action

In this section of the preamble, the EPA sets forth its final
decisions on the two issues for which reconsideration was granted and
on which the EPA solicited comment in the proposed document of
reconsideration. We also present the Agency's rationale for the
decisions.

A. Issue 1: Use of the EPA's IRIS Value for Ethylene Oxide in Assessing
Cancer Risk for the Source Category

1. EPA's Final Decision on the Use of the IRIS Value for Ethylene Oxide
In Assessing Cancer Risk For The Source Category
After careful consideration of the comments and information
submitted through the public comment process for this rulemaking, the
Agency has decided that use of the EPA IRIS value for ethylene oxide
for the risk assessment performed for the 2020 MON final rule was
appropriate. As described in the reconsideration proposal (87 FR 6466,
6471; February 4, 2022), EPA has an established approach supported by
the Science Advisory Board for selecting dose-response values for the
CAA section 112(f)(2) risk reviews.4 5 Application of this
approach generally results in an EPA IRIS value being given preference
over values from other organizations or agencies. Neither the
petitioners nor commenters identified a basis for the EPA to deviate
from this documented approach for selecting dose-response values for
use in the risk assessment for the 2020 MON final rule. Further, the
EPA IRIS assessment of ethylene oxide is scientifically sound, as
evidenced by the toxicological assessment itself,\6\ as well as the
supporting technical documentation. As described in section III.A.2
below and in greater detail in sections 4.1.1 and 4.1.2 of the response
to comment document for this rulemaking, the IRIS assessment underwent
an extensive peer and public review process that adhered to the
guidelines in EPA's Peer Review Handbook \7\ for peer review of highly
influential scientific assessments. The IRIS assessment and supporting
documentation provide evidence of full consideration of the array of
scientific questions and comments presented to the EPA and addressed by
the EPA prior to issuing the final assessment in December 2016. In
addition, since the issuance of the final assessment, there is no new
scientific information that would alter EPA's derivation of the IRIS
value or other aspects of the EPA IRIS assessment for ethylene oxide.
The IRIS assessment continues to provide sound scientific conclusions
that are consistent with the latest scientific knowledge. For these
reasons, which are addressed in section III.A.2 below, and in greater
detail in the response to comment document for this rulemaking, the EPA
IRIS value for ethylene oxide is the most appropriate risk value to use
in assessing cancer risk for the MON Source category.
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\4\ U.S. EPA. Risk and Technology Review (RTR) Risk Assessment
Methodologies: For Review by the EPA's Science Advisory Board with
Case Studies--MACT I Petroleum Refining Sources and Portland Cement
Manufacturing, June 2009. EPA-452/R-09-006. <a href="https://www3.epa.gov/airtoxics/rrisk/rtrpg.html">https://www3.epa.gov/airtoxics/rrisk/rtrpg.html</a>.
\5\ Recommendations of the SAB Risk and Technology Review
Methods Panel are provided in their report, which is available at:
<a href="https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=P100RODV.txt">https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=P100RODV.txt</a> and in the
docket for this rulemaking (see Docket ID No. EPA-HQ-OAR-2018-0746).
\6\ U.S. EPA. Evaluation of the Inhalation Carcinogenicity of
Ethylene Oxide (CASRN 75-21-8) In Support of Summary Information on
the Integrated Risk Information System (IRIS). December 2016. EPA/
635/R-16/350Fa. Available at: <a href="https://cfpub.epa.gov/ncea/iris/iris_documents/documents/toxreviews/1025tr.pdf">https://cfpub.epa.gov/ncea/iris/iris_documents/documents/toxreviews/1025tr.pdf</a> and in the docket for
this rulemaking (see Docket ID No. EPA-HQ-OAR-2018-0746).
\7\ U.S. EPA, 2015. Peer Review Handbook, 4th edition. Science
and Technology Policy Council. October 2015. EPA/100/B-15/001.
<a href="https://www.epa.gov/sites/production/files/2016-03/documents/epa_peer_review_handbook_4th_edition.pdf">https://www.epa.gov/sites/production/files/2016-03/documents/epa_peer_review_handbook_4th_edition.pdf</a>
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2. Comments Received on the Use of the EPA's IRIS Value for Ethylene
Oxide In Assessing Cancer Risk for the Source Category
The Agency received a range of comments on the proposed rule. While
many commenters agreed with the use of EPA's IRIS value for ethylene
oxide, several commenters disagreed with EPA's choice to rely on the
Agency's IRIS assessment, as opposed to TCEQ's assessment, as the
source of the value used to calculate cancer risk from ethylene oxide
exposure.
Many of the comments submitted regarding the EPA IRIS assessment of
ethylene oxide have been addressed previously by the EPA as part of the
extensive peer review and public review process of the draft IRIS
assessment of ethylene oxide. For those comments challenging the IRIS
assessment, documented in detail in the response to comment document
for this rulemaking, we cite to our previous responses. For example, we
again received comments claiming that potential background levels of
ethylene oxide (ethylene oxide present in ambient air or produced
through metabolism in a person's body (i.e., endogenously)) contribute
to cancer risk but were not accounted for in the calculation of the
cancer risk value. We have addressed these comments previously in the
2020 MON final rule \8\ and in the IRIS Assessment for ethylene
oxide,\9\ in addition to the EPA's December 13, 2021, response \10\ to
the Request for Correction (RFC) \11\ of the IRIS value that was
submitted to the EPA by petitioner ACC under the Information Quality
Act, Public Law 106-554 (IQA). We cite these responses in the response
to comment document for this rulemaking, where we explain:
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\8\ Summary of Public Comments and Responses for the Risk and
Technology Review for Miscellaneous Organic Chemical Manufacturing.
<a href="https://www.regulations.gov/document/EPA-HQ-OAR-2018-0746-0200">https://www.regulations.gov/document/EPA-HQ-OAR-2018-0746-0200</a>.
\9\ U.S. EPA. Evaluation of the Inhalation Carcinogenicity of
Ethylene Oxide (CASRN 75-21-8) In Support of Summary Information on
the Integrated Risk Information System (IRIS). December 2016. EPA/
635/R-16/350Fa. See Appendix K, p. K-9. Available at: <a href="https://cfpub.epa.gov/ncea/iris/iris_documents/documents/toxreviews/1025tr.pdf">https://cfpub.epa.gov/ncea/iris/iris_documents/documents/toxreviews/1025tr.pdf</a> and in the docket for this rulemaking (see Docket ID No.
EPA-HQ-OAR-2018-0746).
\10\ U.S. EPA. EPA's Response to American Chemistry Council
(ACC)'s Request for Correction to the IRIS Value for Ethylene Oxide
(EtO) used in the National Air Toxics Assessment (NATA) in 2018.
December 13, 2021. Available at: <a href="https://www.epa.gov/quality/epa-information-qualityguidelines-requestscorrection-and-requestsreconsideration#18003">https://www.epa.gov/quality/epa-information-qualityguidelines-requestscorrection-and-requestsreconsideration#18003</a> and in the docket for this rulemaking
(see Docket ID No. EPA-HQ-OAR-2018-0746).
\11\ American Chemistry Council. Request for Correction under
the Information Quality Act: 2014 National Air Toxics Assessment
(NATA). September 20, 2018. Available at: <a href="https://www.epa.gov/quality/epa-information-qualityguidelines-requests-correction-and-requestsreconsideration#18003">https://www.epa.gov/quality/epa-information-qualityguidelines-requests-correction-and-requestsreconsideration#18003</a> and in the docket for this rulemaking
(see Docket ID No. EPA-HQ-OAR-2018-0746).
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It is important to recognize that the IRIS [unit] risk estimate for
EtO represents the increased cancer risk due to exposure to ethylene
oxide emissions--above any potential existing risks from endogenous or
ambient background levels of EtO exposure. The occupational exposures
in the NIOSH study represent workplace EtO levels these workers
experienced--and are in addition to any endogenous or broad population
background exposures to which the workers may also have been exposed.

[[Page 77990]]

In this section, we describe specific comment topics central to our
rationale for EPA's decision to continue to use the EPA IRIS value;
detailed comment summaries and responses are presented in the response
to comment document for this rulemaking.
a. Comments Concerning Selection of Dose-Response Values for CAA
Section 112(f)(2) Risk Reviews
EPA received a number of comments in support of and against the use
of the EPA IRIS value for ethylene oxide. As described in the
reconsideration proposal (87 FR 6466, 6471; February 4, 2022), EPA has
a documented approach for selecting dose-response values for the CAA
section 112(f)(2) risk reviews. For these risk reviews, the EPA
performs health risk assessments for the hazardous air pollutants (HAP)
that are emitted from the source category after imposition of MACT
standards under CAA section 112(d)(2). Consistent with the purpose of
the IRIS database and the advice from the EPA SAB, and as described in
the risk assessment documentation for the 2020 MON final rule,\12\ the
IRIS database is the preferred source of chronic dose-response data.
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\12\ Residual Risk Assessment for the Miscellaneous Organic
Chemical Manufacturing Source Category in Support of the 2020 Risk
and Technology Review: Final Rule, August 2020. Available at:
<a href="https://www.regulations.gov/document/EPA-HQOAR-2018-0746-0189">https://www.regulations.gov/document/EPA-HQOAR-2018-0746-0189</a>.
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Based on EPA's careful review, the Agency has determined that
neither the petitioners requesting that EPA reconsider the 2020 MON
final rule nor commenters on the proposed reconsideration identified a
basis for EPA to change our approach generally, nor our approach to the
risk assessment specifically in the 2020 MON final rule. Where
commenters identified specific topics, such as new analyses or
information related to the cancer risk value for ethylene oxide, we
address those comments either in the preamble to this final action or
in sections 3 and 4 of the response to comment document for this
action.
b. Comments About the EPA IRIS Assessment of Ethylene Oxide Being
Scientifically Sound and Robust
Some commenters oppose the use of the ethylene oxide IRIS value,
for the most part reiterating previously provided comments (e.g., on
model selection) and citing information that the Agency has already
considered, including in the development of the IRIS assessment or the
2020 MON final rule. Where new comments or information have been
provided, we address those in this preamble or in the response to
comment document for this rulemaking.
Many commenters supporting the use of the EPA IRIS value reiterated
that the IRIS value must be applied because it reflects the latest
scientific knowledge and is the result of an extensive review process.
The EPA agrees that the EPA IRIS assessment is scientifically sound and
robust and represents the best estimate of the increased cancer risk
posed by inhalation exposure to ethylene oxide for use in a risk
assessment. This is evidenced by the toxicological assessment itself
\13\ and its supporting technical documentation, as well as the
extensive peer and public review process that was an integral part of
the development of the final assessment.
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\13\ U.S. EPA. Evaluation of the Inhalation Carcinogenicity of
Ethylene Oxide (CASRN 75-21-8) In Support of Summary Information on
the Integrated Risk Information System (IRIS). December 2016. EPA/
635/R-16/350Fa. Available at: <a href="https://cfpub.epa.gov/ncea/iris/iris_documents/documents/toxreviews/1025tr.pdf">https://cfpub.epa.gov/ncea/iris/iris_documents/documents/toxreviews/1025tr.pdf</a> and in the docket for
this rulemaking (see Docket ID No. EPA-HQ-OAR-2018-0746).
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Many of the comments received on the peer and public review of the
EPA IRIS ethylene oxide assessment have been addressed previously by
the EPA. Specifically, as stated in the response to comments received
on the 2020 MON final rule,\14\ the EPA followed its standard review
process in the ethylene oxide IRIS assessment, which included multiple
rounds of review and comment by experts and the public. This included
internal agency review, interagency review, public external peer
review, and public review. The ethylene oxide IRIS assessment underwent
two peer and public review processes over a 10-year period. After the
second peer and public review, the Agency followed its normal process
to finalize the assessment by considering the peer and public review
comments received, making final revisions to the assessment in response
to those comments, and then issuing the final ethylene oxide IRIS
assessment.
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\14\ Summary of Public Comments and Responses for the Risk and
Technology Review for Miscellaneous Organic Chemical Manufacturing,
August 2020. See section 4.1.3, response to Comment 29. Available
at: <a href="https://www.regulations.gov/document/EPA-HQ-OAR-2018-0746-0200">https://www.regulations.gov/document/EPA-HQ-OAR-2018-0746-0200</a>.
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Given this process, the EPA stated that it disagreed with comments
suggesting that scientific information and comments were not fully
addressed during the IRIS assessment development and review process. In
responding to these comments, the EPA further noted the Agency's
adherence to the guidelines in the EPA's Peer Review Handbook \15\ for
highly influential scientific assessments. The IRIS assessment itself
and supporting documentation provide evidence of full consideration of
the array of scientific questions and comments presented to the EPA.
Responses to new comments received regarding statistical support for
the IRIS dose-response model are included in the response to comments
document.
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\15\ U.S. EPA, 2015. Peer Review Handbook, 4th edition. Science
and Technology Policy Council. October 2015. EPA/100/B-15/001.
<a href="https://www.epa.gov/sites/production/files/2016-03/documents/epa_peer_review_handbook_4th_edition.pdf">https://www.epa.gov/sites/production/files/2016-03/documents/epa_peer_review_handbook_4th_edition.pdf</a>.
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As described in the EPA's Peer Review Handbook,\16\ there are a
range of types of peer review. For the ethylene oxide IRIS assessment,
the Agency requested review by the EPA SAB. The EPA's SAB is a
statutorily established committee with a broad mandate to provide
advice and recommendations to the Agency on scientific and technical
matters. The SAB considers requests for advice and peer review from
across the Agency as part of an annual process, initiated by a request
from the Deputy Administrator to the EPA's senior leadership to
identify requests for review by the EPA. Highly influential scientific
assessments, such as IRIS assessments, or other scientific work
products associated with highly visible or controversial environmental
issues are most suited to review by the SAB. Much of the SAB's peer
review work is done using ad hoc panels formed to review specific EPA
draft technical products. All SAB panels provide advice through the
chartered SAB, which is composed of approximately 50 nationally
renowned scientists, engineers and economists who are screened for
conflicts of interest. The chartered SAB further reviews reports
prepared by project-specific panels, accepts further public comment,
and reports final conclusions directly to the EPA Administrator.
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\16\ Id.
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In addition, to address concerns raised about opportunities for
review of the draft IRIS assessment, it is important to note that the
assessment review and revision process took place over a 10-year
period, from 2006 to 2016. Stakeholders, including the American
Chemistry Council, had an awareness of the Agency's IRIS assessment
early in the process, as evidenced by their review of the 2006 and 2013
draft IRIS assessments and the extensive comments that the ACC and
other stakeholders provided on those drafts.
After completion of an initial draft of the assessment, the EPA
undertook an

[[Page 77991]]

extensive, transparent review process. We agree with commenters who
stated that the ethylene oxide assessment underwent extensive internal
EPA review, as well as external review by other federal agencies.
Drafts of the assessment were available for public comment at three
different times and were twice submitted for external peer review by
the SAB, which is an additional round of external review than is
typically received by IRIS assessments. It is correct that at least
four drafts of the IRIS ethylene oxide cancer evaluation were reviewed
by a wide range of ``EPA scientists, interagency reviewers from other
federal agencies and the Executive Office of the President, the public,
and independent scientists external to the EPA.'' \17\
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\17\ U.S. EPA. Evaluation of the Inhalation Carcinogenicity of
Ethylene Oxide (CASRN 75-21-8) In Support of Summary Information on
the Integrated Risk Information System (IRIS). December 2016. EPA/
635/R-16/350Fa. Available at: <a href="https://cfpub.epa.gov/ncea/iris/iris_documents/documents/toxreviews/1025tr.pdf">https://cfpub.epa.gov/ncea/iris/iris_documents/documents/toxreviews/1025tr.pdf</a> and in the docket for
this rulemaking (see Docket ID No. EPA-HQ-OAR-2018-0746).
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Not only did the SAB reviews involve large panels of experts with
diverse expertise; they also provided opportunity for public comment
and SAB consideration of that comment. EPA's IRIS assessment methods
and conclusions directly relied on detailed recommendations presented
by the SAB (e.g., SAB, 2015, page 9 presents specific recommendations
on preferred dose-response models). The EPA has determined that the
IRIS assessment is scientifically sound and robust and represents the
best inhalation cancer risk value for ethylene oxide.
c. Comments Suggesting That There Is New Scientific Information That
Would Alter Aspects of the EPA IRIS Assessment
Regarding comments questioning EPA's use of the best available and
most recent scientific knowledge, EPA has carefully considered the
range of information submitted to EPA on the IRIS assessment since its
issuance in 2016. This includes, for example, the EPA's response to the
ACC's Request for Correction of the use of the IRIS value for ethylene
oxide.\18\ The Agency's response documents further evidence of
consideration of scientific information submitted to the EPA on the
assessment of ethylene oxide since the IRIS assessment was issued in
2016. While there have been several new publications since issuance of
the final ethylene oxide IRIS assessment in December 2016, those
publications most pertinent to developing an inhalation cancer risk
value for ethylene oxide have focused on re-analyses of published
studies previously considered in the 2016 IRIS assessment and,
therefore, yield no new scientific information. EPA is not aware of new
epidemiological, toxicological, or basic scientific studies that
suggest the current cancer risk value is no longer appropriate or that
could fundamentally alter the basis for the current ethylene oxide IRIS
assessment. Specifically, there is no new scientific information that
would alter aspects of the EPA IRIS assessment or call into question
the scientific judgements reflected in that assessment. The IRIS value
for ethylene oxide continues to reflect the latest scientific
knowledge.
---------------------------------------------------------------------------

\18\ U.S. EPA. EPA's Response to American Chemistry Council
(ACC)'s Request for Correction to the IRIS Value for Ethylene Oxide
(EtO) used in the National Air Toxics Assessment (NATA) in 2018.
December 13, 2021. Available at: <a href="https://www.epa.gov/quality/epa-information-qualityguidelines-requests-correction-and-requestsreconsideration#18003">https://www.epa.gov/quality/epa-information-qualityguidelines-requests-correction-and-requestsreconsideration#18003</a> and in the docket for this rulemaking
(see Docket ID No. EPA-HQ-OAR-2018-0746).
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B. Issue 2: Use of the TCEQ Risk Value for Ethylene Oxide in Assessing
Cancer Risk for the Source Category

1. EPA's Final Decision on the Use of the TCEQ Risk Value for Ethylene
Oxide in Assessing Cancer Risk for the Source Category
After careful consideration of the final TCEQ assessment \19\ and
comments and information submitted through the public comment process
for this rulemaking, the Agency finds that the TCEQ risk value is
unsuitable for use as an alternative to the IRIS value for ethylene
oxide in assessing cancer risk under CAA section 112(f).
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\19\ Ethylene Oxide Carcinogenic Dose-Response Assessment:
Development Support Document, May 15, 2020. Texas Commission on
Environmental Quality. <a href="https://www.tceq.texas.gov/downloads/toxicology/dsd/final/eto.pdf">https://www.tceq.texas.gov/downloads/toxicology/dsd/final/eto.pdf</a>.
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The EPA disagrees with several foundational aspects of the final
TCEQ assessment. First, EPA disagrees with TCEQ's decision to exclude
breast cancer in women as an endpoint for ethylene oxide dose response
assessment. EPA finds that TCEQ's decision to exclude breast cancer in
women in their derivation of the ethylene oxide risk value is not
scientifically sound; this decision reduces the accuracy of, and
confidence in, the TCEQ risk value as an appropriate metric of
increased cancer risk from inhalation exposure to ethylene oxide.
Second, with regard to TCEQ's dose-response modeling, the EPA finds
that: (1) the dose-response model selected by TCEQ is unsupported by
the underlying epidemiological data, and (2) TCEQ's analyses to justify
their model choice were erroneous and relied on flawed assumptions. For
the reasons listed here and described in detail in section III.B.2
below, as well as in the response to comment document for this
rulemaking, the TCEQ risk value for ethylene oxide is not appropriate
to use in assessing cancer risk for the MON Source category.
2. Comments Received on the Use of the TCEQ Risk Value for Ethylene
Oxide in Assessing Cancer Risk for the Source Category
While many commenters were opposed to EPA's use of the TCEQ risk
value for ethylene oxide, several commenters were in favor of the use
of the TCEQ value. In this section, we describe specific comment topics
key to explaining the rationale for EPA's decision to reject the use of
the TCEQ risk value for assessing cancer risk for the source category;
detailed comment summaries and responses are presented in the response
to comment document for this rulemaking.
a. Comments on Inclusion and Exclusion of Breast Cancer as an Endpoint
While many commenters agree with the inclusion of breast cancer as
an endpoint in the dose-response assessment of ethylene oxide, as was
done in the EPA IRIS assessment, several commenters, including TCEQ and
ACC, support exclusion of breast cancer as an endpoint, as was done in
the final TCEQ assessment of ethylene oxide.
EPA disagrees with TCEQ and other commenters who support exclusion
of breast cancer in women as an endpoint when assessing the cancer risk
from exposure to ethylene oxide. In the IRIS assessment of ethylene
oxide, the EPA determined that the available epidemiological evidence
for a causal relationship between ethylene oxide exposure and breast
cancer in women was strong, and there were sufficient data to include
breast cancer in the derivation of the IRIS value for ethylene oxide.
The SAB supported this determination. Comments on the evidence for
breast cancer as an endpoint following ethylene oxide exposure were
also addressed during the review process for the IRIS ethylene oxide
assessment. For example, in response to a public comment on the IRIS
2013 draft claiming that the evidence for breast cancer is too weak to
rely on in setting the URE, the EPA responded: ``Although the
epidemiological database for breast

[[Page 77992]]

cancer is more limited (i.e., few studies with sufficient numbers of
female breast cancer cases) than that for lymphohematopoietic cancers,
the EPA determined that the available evidence is sufficient to
consider breast cancer a potential hazard from ethylene oxide exposure
. . . The 2007 SAB panel did not object to the derivation of unit risk
estimates based on the available breast cancer evidence.'' \20\ The
IRIS cancer risk value is representative of potential health risks to
the general population because it reflects the combined cancer risk of
developing lymphoid cancers in all people, and breast cancer in women.
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\20\ U.S. EPA. Evaluation of the Inhalation Carcinogenicity of
Ethylene Oxide (CASRN 75-21-8) In Support of Summary Information on
the Integrated Risk Information System (IRIS). December 2016. EPA/
635/R-16/350Fa. Appendix K, p. K-3. Available at: <a href="https://cfpub.epa.gov/ncea/iris/iris_documents/documents/toxreviews/1025tr.pdf">https://cfpub.epa.gov/ncea/iris/iris_documents/documents/toxreviews/1025tr.pdf</a> and in the docket for this rulemaking (see Docket ID No.
EPA-HQ-OAR-2018-0746).
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EPA examined what TCEQ describes as new scientific information and
found it to primarily consist of publications providing further reviews
covering the same epidemiological data on breast cancer that had
already been comprehensively reviewed in the EPA's ethylene oxide IRIS
assessment. EPA's examination of these review articles finds that the
authors of these journal article reviews have mostly dismissed the
strongest data on ethylene oxide and breast cancer, and EPA finds these
decisions to be unwarranted. Comments against the inclusion of breast
cancer cite two meta-analyses addressing ethylene oxide breast cancer
studies that were published after the completion of the 2016 IRIS
assessment (Marsh et al. (2019). Both reviews included five breast
cancer studies, all of which were examined in the IRIS assessment
(Coggon, 2004; Mikoczy, 2011; Norman, 1995; Steenland, 2003; and
Steenland, 2004). The conclusions of these meta-analyses are flawed for
two major reasons: (1) the authors did not consider findings of
increased cancer incidence or mortality in highly exposed study
subgroups, and (2) the authors excluded published findings using
internal comparison groups within the worker populations, which goes
against best practice in epidemiology.\21\ Consequently, the meta-
analyses inappropriately omitted all positive findings from the
Steenland et al. (2003 and 2004) and Mikoczy et al. (2011) studies for
breast cancer mortality and incidence and treated these studies as
providing negative evidence of an effect of ethylene oxide on breast
cancer. These flawed re-analyses of data (data that had been previously
reviewed in the IRIS assessment and found to provide positive evidence)
led the authors to conclude that the weight of evidence does not
support breast cancer as an endpoint.
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\21\ Internal comparisons are particularly valuable, as they
provide a basis for examining compound-related increases in cancer
rates without relying on an assumption that cancer rates in the
studied workers would be identical to general population average
cancer rates in the absence of exposure to the compound.
---------------------------------------------------------------------------

EPA also examined a new study by Jain (2020) using NHANES data to
investigate associations between exposure to ethylene oxide in tobacco
smoke and self-reported diagnosis of cancers. The author concluded that
levels of ethylene oxide in the general population in the U.S. were not
found to be associated with cancers, including breast cancer. There are
three major issues that call into question the interpretation of the
results from this study. First, it appears that Jain misleadingly
interpreted a biomarker of exposure as ``[ethylene oxide] levels in the
blood''. Importantly, since NHANES did not measure ethylene oxide
levels in the blood, this suggests a misunderstanding of the NHANES
data consistent with Jain's overinterpretation of the results. Second,
Jain failed to note the large number of unaccounted-for variables that
may contribute to one's lifetime breast cancer risk, such as lifestyle,
a history of breast cancer in relatives, co-exposures, and cumulative
exposure to ethylene oxide and other chemicals. NHANES provides cross-
sectional data representing a snapshot in time of exposure and health
outcome and is not designed to establish temporal causality between
chemical exposure and cancer outcomes. For this reason, NHANES data
cannot be used to reliably rule out causation between chemical exposure
and breast cancer. Third, biomarker measurements that offer a snapshot
in time of one's exposure to chemicals are not necessarily
representative of continuous, lifetime exposure leading to the
development of breast cancer. Taken together, the Jain study results do
not support the author's conclusion.
EPA disagrees with commenters that dismiss the breast cancer
findings in the National Institute for Occupational Safety and Health
(NIOSH) studies of sterilizer workers. Available epidemiologic data
provide strong evidence of an elevated breast cancer risk in female
workers exposed to ethylene oxide. Results from the NIOSH studies of
sterilizer workers (Steenland et al., 2003, and Steenland et al., 2004)
demonstrate excess breast cancer risk, substantiated through several
different epidemiological analysis approaches. Other smaller studies
also indicate an elevated breast cancer risk. No substantial studies
challenge this conclusion. The breast cancer findings from the studies
of Steenland et al. (2003, 2004) are broadly regarded as the largest
and most detailed studies of this endpoint. These studies presented
cancer findings for the NIOSH cohort of workers at U.S. sterilization
facilities with Steenland et al. (2004) examining cancer mortality
rates for breast and other cancers and Steenland et al. (2003)
specifically studying incidence (occurrence of disease) of breast
cancer. Particularly for breast cancer in women (who are not adequately
represented in some industrial cohorts), the NIOSH study is generally
regarded as preeminent. These cancer mortality and incidence studies
include multiple statistical comparisons that provide evidence of the
effect of ethylene oxide exposure increasing breast cancer rates. EPA
reaffirms that it is sound and reasonable to include breast cancer as a
major endpoint in the IRIS ethylene oxide assessment. Detailed comment
summaries and responses on this subject are provided in the response to
comment document for this rulemaking.
For these reasons, the EPA finds TCEQ's decision to exclude breast
cancer as an endpoint in the derivation of their ethylene oxide risk
value to be without adequate scientific basis.
b. Comments on Dose-Response Model Selection
EPA received a range of comments regarding the dose-response model
selection for the final TCEQ assessment and for the EPA IRIS
assessment. A number of the comments submitted on the reconsideration
proposal were on aspects of the dose-response model that EPA had
previously addressed either in the peer review of the EPA IRIS ethylene
oxide assessment \22\ or in the response to comment document for the
2020 MON final rule.\23\ New comments regarding TCEQ's assessment
focused primarily on support for, and opposition to, the model itself
and TCEQ's analyses to support the model selected.
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\22\ U.S. EPA. Evaluation of the Inhalation Carcinogenicity of
Ethylene Oxide (CASRN 75-21-8) In Support of Summary Information on
the Integrated Risk Information System (IRIS). December 2016. EPA/
635/R-16/350Fa. Available at: <a href="https://cfpub.epa.gov/ncea/iris/iris_documents/documents/toxreviews/1025tr.pdf">https://cfpub.epa.gov/ncea/iris/iris_documents/documents/toxreviews/1025tr.pdf</a> and in the docket for
this rulemaking (see Docket ID No. EPA-HQ-OAR-2018-0746-0202).
\23\ Summary of Public Comments and Responses for the Risk and
Technology Review for Miscellaneous Organic Chemical Manufacturing,
August 2020. Available at: <a href="https://www.regulations.gov/document/EPA-HQ-OAR-2018-0746-0200">https://www.regulations.gov/document/EPA-HQ-OAR-2018-0746-0200</a>.
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After examining the final TCEQ assessment, as well as analyses and

[[Page 77993]]

arguments submitted as part of the public comment process for the MON
reconsideration proposed rulemaking, the EPA disagrees with TCEQ's
model selection, including TCEQ's claim that the biological evidence
supports a model with a single, gradual slope through the full range of
both general population and occupational exposures. For their model
selection, TCEQ chose a model that is inconsistent with the underlying
epidemiological data, particularly for ethylene oxide levels in the
range of general population exposure (where the general population
would include children and other potentially vulnerable groups), which
is of most relevance for the CAA section 112 risk assessments.
The epidemiological data indicate that cancer risk rises more
rapidly with increasing exposure in the lower exposure range and more
gradually in the higher exposure range. TCEQ selected a model that is
unable to fit the shape of the data throughout the exposure range. The
slope of TCEQ's model is more representative of higher, occupational
exposures. By using a single slope (a line) to project risks, TCEQ's
model predicts risks at lower exposure ranges that are inconsistent
with the underlying epidemiological dose-response data. EPA rejects
TCEQ's model because it is inconsistent with the underlying
epidemiological dose-response data and mischaracterizes risk at the
lower exposure range (i.e., the range representing potential general
population exposures).
It is important to note that, as part of the ethylene oxide IRIS
assessment, EPA considered and evaluated 12 dose-response models for
lymphoid cancer mortality and 9 dose-response models for breast cancer
incidence. The dose-response model selected by TCEQ (a Cox proportional
hazards model) is one of the models that was considered by the EPA as
part of the IRIS assessment. EPA found that the linear curve selected
by TCEQ was highly influenced by the uppermost 5% of the exposure range
and did not fit the full range of epidemiological data points, leading
to an underestimation of risk for points below the highest exposure
levels. After considering all models, EPA found that the two-piece
spline model best captured the initial increase in risk at lower doses
followed by an attenuation at higher doses. Spline models are generally
useful for exposure-response data in which risk increases with exposure
at low doses but attenuates at higher exposures, as observed in the
ethylene oxide lymphoid cancer data. The plateauing exposure-response
relationship has been observed for other occupational carcinogens and
may be explained by the depletion of susceptible subpopulations at high
exposures, mismeasurement of high exposures, or a healthy worker
survivor effect (Stayner et al., 2003). The EPA subsequently rejected
the model selected by TCEQ, as well as other similar models, and
selected a two-piece linear spline model. In its response to the SAB's
recommendations,\24\ the EPA noted: ``The EPA has followed the SAB's
recommendations for model selection. Model selection for both the
breast cancer incidence (see section 4.1.2.3) and lymphoid cancer (see
section 4.1.1.2) data prioritizes functional forms that allow more
local fits in the low exposure range (e.g., spline models), relies less
on AIC,\25\ and includes consideration of biological plausibility . .
.'' As such, in the ethylene oxide IRIS assessment, the EPA selected a
model that best represented potential general population exposures,
making it align well with the purpose of the risk assessment in the
2020 MON final rule, which sought to assess general risk exposure to
the public. Importantly, EPA found TCEQ's chosen model to be a poor fit
of the data in the low exposure range (i.e., the range representing
potential general population exposures).\26\
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\24\ U.S. EPA. Evaluation of the Inhalation Carcinogenicity of
Ethylene Oxide (CASRN 75-21-8) In Support of Summary Information on
the Integrated Risk Information System (IRIS). December 2016. EPA/
635/R-16/350Fa. See Appendix I, p. I-3. Available at: <a href="https://cfpub.epa.gov/ncea/iris/iris_documents/documents/toxreviews/1025tr.pdf">https://cfpub.epa.gov/ncea/iris/iris_documents/documents/toxreviews/1025tr.pdf</a> and in the docket for this rulemaking (see Docket ID No.
EPA-HQ-OAR-2018-0746-0202).
\25\ The Akaike information criterion (AIC) is a mathematical
model for evaluating how well a model fits the underlying dataset
from which it was generated.
\26\ U.S. EPA. EPA's Response to American Chemistry Council
(ACC)'s Request for Correction to the IRIS Value for Ethylene Oxide
(EtO) used in the National Air Toxics Assessment (NATA) in 2018.
December 13, 2021. Available at: <a href="https://www.epa.gov/quality/epa-information-qualityguidelines-requests-correction-and-requestsreconsideration#18003">https://www.epa.gov/quality/epa-information-qualityguidelines-requests-correction-and-requestsreconsideration#18003</a> and in the docket for this rulemaking
(see Docket ID No. EPA-HQ-OAR-2018-0746-0264).
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Unlike model selection for the TCEQ assessment of ethylene oxide,
for the ethylene oxide IRIS assessment, EPA selected the model that
best represented potential general population exposures, as well as
higher, occupational exposures. EPA's statistical model selection was
based on model fit with the observed results in the NIOSH study and was
consistent with peer review advice received from the SAB. In the
terminology of cancer risk assessment and EPA's Carcinogen Guidelines,
the EPA two-piece linear spline model predicts a linear association
between environmentally relevant ethylene oxide exposures and cancer
risk.\27\ SAB (2015) peer review comments noted consistency in model
fit and categorical results.\28\
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\27\ Ibid.
\28\ SAB. (2015). Science Advisory Board Review of the EPA's
Evaluation of the Inhalation Carcinogenicity of Ethylene Oxide:
Revised external review draft--August 2014 [EPA Report]. (EPA-SAB-
15-012). Washington, DC: U.S. EPA, SAB.Available at: <a href="https://yosemite.epa.gov/sab/sabproduct.nsf/fedrgstr">https://yosemite.epa.gov/sab/sabproduct.nsf/fedrgstr</a>_activites/
BD2B2DB4F84146A585257E9A0070E655/$File/EPA-SAB-15-012+unsigned.pdf
and in the docket for this rulemaking (see Docket ID No. EPA-HQ-OAR-
2018-0746).
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In addition to disagreeing with the dose-response model selected by
TCEQ, EPA also disagrees with TCEQ's analytical approach to justifying
its model selection. TCEQ supported their model choice using flawed
calculations and inappropriate assumptions. TCEQ takes an approach that
they claim allows for statistical testing of model predictions. EPA has
examined TCEQ's inferences and calculations and has identified problems
with: (1) TCEQ's assumption that national lymphoid cancer mortality
rates equal rates of cancer mortality for members of the NIOSH cohort
in the absence of ethylene oxide exposures; (2) TCEQ's calculation of
projected cancer rates; and (3) the statistical confidence intervals
TCEQ developed for the ``predicted'' numbers of cancers. These are
summarized below and described in greater detail in the response to
comment document for this rulemaking.
TCEQ made errors in their calculation of projected cancer rates and
in the ``reality check'' calculations they used to justify their model
choice. TCEQ's ``reality check'' calculations are not statistically
appropriate and do not support TCEQ's claims. Further, TCEQ relied on
flawed assumptions. For example, in making a claim that TCEQ's model
more accurately predicts cancers attributable to ethylene oxide
exposure, TCEQ incorrectly assumes that, in the absence of ethylene
oxide exposure, cancer incidence rates in the worker cohort (the basis
of the URE calculation in EPA's IRIS assessment) would be the same as
national cancer mortality rates for the general population. This is, at
best, a rough approximation and is subject to considerable error.
Importantly, the development of Cox model ``internal'' risk estimates
instead of a national mortality rate-based analysis by Steenland et al.
(2004) reflects that comparisons to national mortality rates are not
appropriate for this worker cohort. Use of an ``internal'' statistical
analysis rather than an

[[Page 77994]]

external (national mortality rate-based) analysis is broadly accepted
as best practice in occupational epidemiology and was endorsed by the
EPA SAB for the EtO IRIS assessment. The EPA disagrees with TCEQ's
approach and these assumptions, as described in detail in the response
to comment document for this rulemaking.
For the reasons stated above, the EPA finds that the dose-response
model selected by TCEQ is unsupported by the data, and the analyses
fail to justify the selection of the model. The TCEQ assessment,
petitions, and the comments submitted as part of this rulemaking
process do not provide a scientifically supportable basis for relying
on the TCEQ risk value to assess the residual risk for sources in the
2020 MON final rule. No new studies or other information have been
identified by TCEQ, the petitioners requesting reconsideration, or the
commenters that would call into question the conclusions in the IRIS
ethylene oxide assessment. The EPA reaffirms its use of the EPA IRIS
value for ethylene oxide for the risk assessment performed for the 2020
MON final rule.

IV. Summary of Cost, Environmental, and Economic Impacts and Additional
Analyses Conducted

A. What are the affected facilities?

We estimate that, as of November 6, 2018, there were 201 MON
facilities, nine of which reported ethylene oxide emissions to the 2014
National Emissions Inventory. However, as the EPA is not finalizing any
changes to the regulatory text or regulatory requirements in this
action, we do not anticipate that any sources will be affected by this
reconsideration. A complete list of known MON facilities is available
in Appendix 1 of the document, Residual Risk Assessment for the
Miscellaneous Organic Chemical Manufacturing Source Category in Support
of the 2019 Risk and Technology Review Proposed Rule, which is
available in the docket for this rulemaking (see Docket Item No. EPA-
HQ-OAR-2018-0746-0011).

B. What are the air quality impacts?

The EPA does not project any air quality impacts associated with
this action because this action does not finalize any changes to the
standards or other requirements on affected sources.

C. What are the cost impacts?

The EPA does not project any incremental costs associated with this
action because it does not finalize any changes to the standards or
other requirements on affected sources.

D. What are the economic impacts?

The EPA does not project any economic impacts because there are no
incremental costs associated with this action.

E. What are the benefits?

The EPA does not project any incremental benefits associated with
this action because it does not finalize any changes to the standards
or other requirements on affected sources.

F. What analysis of environmental justice did we conduct?

The EPA believes that this action is not subject to Executive Order
12898 (59 FR 7629, February 16, 1994) because it does not establish an
environmental health or safety standard. This regulatory action acts to
reaffirm decisions made in a previously promulgated regulatory action
and does not have any impact on human health or the environment.

G. What analysis of children's environmental health did we conduct?

This action is not subject to Executive Order 13045 because it is
not economically significant, as defined in Executive Order 12866, and
because this action does not present any changes to the rule that would
affect environmental health or safety risks, including those that would
present a disproportionate risk to children.

V. Statutory and Executive Order Reviews

Additional information about these statutes and Executive Orders
can be found at <a href="https://www.epa.gov/laws-regulations/laws-and-executive-orders">https://www.epa.gov/laws-regulations/laws-and-executive-orders</a>.

A. Executive Order 12866: Regulatory Planning and Review and Executive
Order 13563: Improving Regulation and Regulatory Review

This action is not a significant regulatory action and was
therefore not submitted to the Office of Management and Budget (OMB)
for review.

B. Paperwork Reduction Act (PRA)

This action does not impose an information collection burden under
the PRA.

C. Regulatory Flexibility Act (RFA)

I certify that this action will not have a significant economic
impact on a substantial number of small entities under the RFA. In
making this determination, the EPA concludes that the impact of concern
for this rule is any significant adverse economic impact on small
entities and that the Agency is certifying that this rule will not have
a significant economic impact on a substantial number of small entities
if the rule has no net burden on the small entities subject to the
rule. As we are not finalizing any changes to the regulatory text or
regulatory requirements, we do not anticipate any economic impacts
resulting from this action. We have therefore concluded that this
action will have no net regulatory burden for all directly regulated
small entities.

D. Unfunded Mandates Reform Act (UMRA)

This action does not contain any unfunded mandate as described in
UMRA, 2 U.S.C. 1531-1538, and does not significantly or uniquely affect
small governments. The action finalizes no enforceable duty on any
state, local or tribal governments or the private sector.

E. Executive Order 13132: Federalism

This action does not have federalism implications. It will not have
substantial direct effects on the states, on the relationship between
the national government and the states, or on the distribution of power
and responsibilities among the various levels of government.

F. Executive Order 13175: Consultation and Coordination With Indian
Tribal Governments

This action does not have tribal implications as specified in
Executive Order 13175. None of the MON facilities that have been
identified as being affected by this action are owned or operated by
tribal governments or located within tribal lands within a 10 mile
radius. Thus, Executive Order 13175 does not apply to this action.

G. Executive Order 13045: Protection of Children From Environmental
Health Risks and Safety Risks

This action is not subject to Executive Order 13045 because it is
not economically significant as defined in Executive Order 12866, and
because this action does not present any changes to the rule that would
affect environmental health or safety risks, including those that would
present a disproportionate risk to children.

H. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use

This action is not subject to Executive Order 13211, because it is
not a

[[Page 77995]]

significant regulatory action under Executive Order 12866.

I. National Technology Transfer and Advancement Act (NTTAA)

This rulemaking does not involve technical standards.

J. Executive Order 12898: Federal Actions To Address Environmental
Justice in Minority Populations and Low-Income Populations

The EPA believes that this action is not subject to Executive Order
12898 (59 FR 7629, February 16, 1994) because it does not establish an
environmental health or safety standard. This regulatory action acts to
clarify the language in the preamble of a previously promulgated
regulatory action and does not have any impact on human health or the
environment.

K. Congressional Review Act (CRA)

This action is subject to the CRA, and the EPA will submit a rule
report to each House of the Congress and to the Comptroller General of
the United States. This action is not a ``major rule'' as defined by 5
U.S.C. 804(2).

List of Subjects in 40 CFR Part 63

Environmental protection, Administrative practice and procedures,
Air pollution control, Hazardous substances, Intergovernmental
relations.

Michael S. Regan,
Administrator.
[FR Doc. 2022-27522 Filed 12-20-22; 8:45 am]
BILLING CODE 6560-50-P

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