Document ID: EPA-HQ-OAR-2018-0746-0322
Agency: epa
Document Type: Rule
Title: National Emission Standards for Hazardous Air Pollutants: Miscellaneous Organic Chemical Manufacturing Residual Risk and Technology Review; 2020 Reconsideration
Posted Date: 2022-12-21T05:00Z

[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 [www.gpo.gov]
[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 https://www.regulations.gov/ 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 
https://www.regulations.gov/, 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: 
[email protected]. 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: [email protected]. 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: 
[email protected].

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: https://www.epa.gov/stationary-sources-air-pollution/miscellaneous-organic-chemical-manufacturing-national-emission. 
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 https://www.regulations.gov/ by searching Docket ID No. EPA-HQ-OAR-2018-0746. 
Additional information is available on the RTR website at https://www.epa.gov/stationary-sources-air-pollution/risk-and-technology-review-national-emissions-standards-hazardous. 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: 
https://www.regulations.gov/document/EPA-HQ-OAR-2018-0746-0189.
    \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: https://cfpub.epa.gov/ncea/iris/iris_documents/documents/toxreviews/1025tr.pdf 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. https://www3.epa.gov/airtoxics/rrisk/rtrpg.html.
    \5\ Recommendations of the SAB Risk and Technology Review 
Methods Panel are provided in their report, which is available at: 
https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=P100RODV.txt 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: https://cfpub.epa.gov/ncea/iris/iris_documents/documents/toxreviews/1025tr.pdf 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. 
https://www.epa.gov/sites/production/files/2016-03/documents/epa_peer_review_handbook_4th_edition.pdf
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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. 
https://www.regulations.gov/document/EPA-HQ-OAR-2018-0746-0200.
    \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: https://cfpub.epa.gov/ncea/iris/iris_documents/documents/toxreviews/1025tr.pdf 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: https://www.epa.gov/quality/epa-information-qualityguidelines-requestscorrection-and-requestsreconsideration#18003 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: https://www.epa.gov/quality/epa-information-qualityguidelines-requests-correction-and-requestsreconsideration#18003 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.
---------------------------------------------------------------------------

    \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: 
https://www.regulations.gov/document/EPA-HQOAR-2018-0746-0189.
---------------------------------------------------------------------------

    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.
---------------------------------------------------------------------------

    \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: https://cfpub.epa.gov/ncea/iris/iris_documents/documents/toxreviews/1025tr.pdf and in the docket for 
this rulemaking (see Docket ID No. EPA-HQ-OAR-2018-0746).
---------------------------------------------------------------------------

    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.
---------------------------------------------------------------------------

    \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: https://www.regulations.gov/document/EPA-HQ-OAR-2018-0746-0200.
---------------------------------------------------------------------------

    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.
---------------------------------------------------------------------------

    \15\ U.S. EPA, 2015. Peer Review Handbook, 4th edition. Science 
and Technology Policy Council. October 2015. EPA/100/B-15/001. 
https://www.epa.gov/sites/production/files/2016-03/documents/epa_peer_review_handbook_4th_edition.pdf.
---------------------------------------------------------------------------

    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.
---------------------------------------------------------------------------

    \16\ Id.
---------------------------------------------------------------------------

    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\
---------------------------------------------------------------------------

    \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: https://cfpub.epa.gov/ncea/iris/iris_documents/documents/toxreviews/1025tr.pdf and in the docket for 
this rulemaking (see Docket ID No. EPA-HQ-OAR-2018-0746).
---------------------------------------------------------------------------

    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: https://www.epa.gov/quality/epa-information-qualityguidelines-requests-correction-and-requestsreconsideration#18003 and in the docket for this rulemaking 
(see Docket ID No. EPA-HQ-OAR-2018-0746).
---------------------------------------------------------------------------

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).
---------------------------------------------------------------------------

    \19\ Ethylene Oxide Carcinogenic Dose-Response Assessment: 
Development Support Document, May 15, 2020. Texas Commission on 
Environmental Quality. https://www.tceq.texas.gov/downloads/toxicology/dsd/final/eto.pdf.
---------------------------------------------------------------------------

    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.
---------------------------------------------------------------------------

    \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: https://cfpub.epa.gov/ncea/iris/iris_documents/documents/toxreviews/1025tr.pdf and in the docket for this rulemaking (see Docket ID No. 
EPA-HQ-OAR-2018-0746).
---------------------------------------------------------------------------

    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.
---------------------------------------------------------------------------

    \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.
---------------------------------------------------------------------------

    \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: https://cfpub.epa.gov/ncea/iris/iris_documents/documents/toxreviews/1025tr.pdf 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: https://www.regulations.gov/document/EPA-HQ-OAR-2018-0746-0200.
---------------------------------------------------------------------------

    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\
---------------------------------------------------------------------------

    \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: https://cfpub.epa.gov/ncea/iris/iris_documents/documents/toxreviews/1025tr.pdf 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: https://www.epa.gov/quality/epa-information-qualityguidelines-requests-correction-and-requestsreconsideration#18003 and in the docket for this rulemaking 
(see Docket ID No. EPA-HQ-OAR-2018-0746-0264).
---------------------------------------------------------------------------

    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\
---------------------------------------------------------------------------

    \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: https://yosemite.epa.gov/sab/sabproduct.nsf/fedrgstr_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).
---------------------------------------------------------------------------

    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 https://www.epa.gov/laws-regulations/laws-and-executive-orders.

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