3906 Federal Register / Vol. 86, No. 10 / Friday, January 15, 2021 / Proposed Rules 

(ii) Within 150 yards from all 

shorelines in Florida. 

(3) PWC are allowed to land at any 

point along the shore except as follows: 

(i) PWC are prohibited on any 

shoreline adjacent to the closed areas 

listed in paragraph (c)(1) of this section; 

and 

* * * * * 

George Wallace, 

Assistant Secretary for Fish and Wildlife and 

Parks. 

[FR Doc. 2021–00312 Filed 1–14–21; 8:45 am] 

BILLING CODE 4310–EJ–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 63 

[EPA–HQ–OAR–2020–0532; FRL–10018–49– 

OAR] 

RIN 2060–AU64 

National Emission Standards for 

Hazardous Air Pollutants: Cyanide 

Chemicals Manufacturing Residual 

Risk and Technology Review 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Proposed rule. 

SUMMARY: The U.S. Environmental 

Protection Agency (EPA) is proposing 

the results of the residual risk and 

technology review (RTR) for the 

National Emission Standards for 

Hazardous Air Pollutants (NESHAP) for 

the Cyanide Chemicals Manufacturing 

source category as required under the 

Clean Air Act (CAA). We are proposing 

to find that risk from emissions of air 

toxics from this source category is 

acceptable, and that the current 

standards provide an ample margin of 

safety to protect public health. We are 

also proposing to find that there are no 

developments in practices, processes, 

and control technologies, and, as such, 

we are not proposing any developmentbased changes to the current standards 

pursuant to the technology review. The 

EPA is, however, proposing new 

emissions standards to address 

emissions from process wastewater at 

existing sources. We are proposing to 

amend provisions addressing startup, 

shutdown, and malfunction (SSM), to 

add electronic reporting, and to update 

the reporting and recordkeeping 

requirements. We do not expect these 

proposed amendments to result in 

changes in emissions from the source 

category but anticipate improved 

monitoring, compliance, and 

implementation of the existing 

standards. 

DATES: Comments must be received on 

or before March 1, 2021. Under the 

Paperwork Reduction Act (PRA), 

comments on the information collection 

provisions are best assured of 

consideration if the Office of 

Management and Budget (OMB) 

receives a copy of your comments on or 

before February 16, 2021. 

Public hearing: If anyone contacts us 

requesting a public hearing on or before 

January 21, 2021, we will hold a virtual 

public hearing. See SUPPLEMENTARY

INFORMATION for information on 

requesting and registering for a public 

hearing. 

ADDRESSES: You may send comments, 

identified by Docket ID No. EPA–HQ– 

OAR–2020–0532, by any of the 

following methods: 

• Federal eRulemaking Portal: 

https://www.regulations.gov/ (our 

preferred method). Follow the online 

instructions for submitting comments. 

• Email: a-and-r-docket@epa.gov. 

Include Docket ID No. EPA–HQ–OAR– 

2020–0532 in the subject line of the 

message. 

• Fax: (202) 566–9744. Attention 

Docket ID No. EPA–HQ–OAR–2020– 

0532. 

• Mail: U.S. Environmental 

Protection Agency, EPA Docket Center, 

Docket ID No. EPA–HQ–OAR–2020– 

0532, Mail Code 28221T, 1200 

Pennsylvania Avenue NW, Washington, 

DC 20460. 

• Hand/Courier Delivery: EPA Docket 

Center, WJC West Building, Room 3334, 

1301 Constitution Avenue NW, 

Washington, DC 20004. The Docket 

Center’s hours of operation are 8:30 

a.m.–4:30 p.m., Monday–Friday (except 

federal holidays). 

Instructions: All submissions received 

must include the Docket ID No. for this 

rulemaking. Comments received may be 

posted without change to https://

www.regulations.gov/, including any 

personal information provided. For 

detailed instructions on sending 

comments and additional information 

on the rulemaking process, see the 

SUPPLEMENTARY INFORMATION section of 

this document. Out of an abundance of 

caution for members of the public and 

our staff, the EPA Docket Center and 

Reading Room are closed to the public, 

with limited exceptions, to reduce the 

risk of transmitting COVID–19. Our 

Docket Center staff will continue to 

provide remote customer service via 

email, phone, and webform. We 

encourage the public to submit 

comments via https://

www.regulations.gov/ or email, as there 

may be a delay in processing mail and 

faxes. Hand deliveries and couriers may 

be received by scheduled appointment 

only. For further information on EPA 

Docket Center services and the current 

status, please visit us online at https:// 

www.epa.gov/dockets. 

FOR FURTHER INFORMATION CONTACT: For 

questions about this proposed action, 

contact Nathan Topham, Sector Policies 

and Programs Division (D243–02), 

Office of Air Quality Planning and 

Standards, U.S. Environmental 

Protection Agency, Research Triangle 

Park, North Carolina 27711; telephone 

number: (919) 541–0483; fax number: 

(919) 541–4991; and email address: 

topham.nathan@epa.gov. For specific 

information regarding the risk modeling 

methodology, contact James Hirtz, 

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– 

0881; fax number: (919) 541–0840; and 

email address: Hirtz.James@epa.gov. 

SUPPLEMENTARY INFORMATION: 

Participation in virtual public hearing. 

Please note that the EPA is deviating 

from its typical approach for public 

hearings because the President has 

declared a national emergency. Due to 

the current Centers for Disease Control 

and Prevention (CDC) 

recommendations, as well as state and 

local orders for social distancing to limit 

the spread of COVID–19, the EPA 

cannot hold in-person public meetings 

at this time. 

To request a virtual public hearing, 

contact the public hearing team at (888) 

372–8699 or by email at 

SPPDpublichearing@epa.gov. If 

requested, the virtual hearing will be 

held on February 1, 2021. The hearing 

will convene at 9:00 a.m. Eastern Time 

(ET) and will conclude at 3:00 p.m. ET. 

The EPA may close a session 15 minutes 

after the last pre-registered speaker has 

testified if there are no additional 

speakers. The EPA will announce 

further details at https://www.epa.gov/ 

stationary-sources-air-pollution/acetalresins-acrylic-modacrylic-fibers-carbonblack-hydrogen. 

The EPA will begin pre-registering 

speakers for the hearing upon 

publication of this document in the 

Federal Register, if a hearing is 

requested. To register to speak at the 

virtual hearing, please use the online 

registration form available at https://

www.epa.gov/stationary-sources-airpollution/acetal-resins-acrylicmodacrylic-fibers-carbon-blackhydrogen or contact the public hearing 

team at (888) 372–8699 or by email at 

SPPDpublichearing@epa.gov. The last 

Federal Register / Vol. 86, No. 10 / Friday, January 15, 2021 / Proposed Rules 3907 

day to pre-register to speak at the 

hearing will be January 27, 2021. Prior 

to the hearing, the EPA will post a 

general agenda that will list preregistered speakers in approximate 

order at: https://www.epa.gov/ 

stationary-sources-air-pollution/acetalresins-acrylic-modacrylic-fibers-carbonblack-hydrogen. 

The EPA will make every effort to 

follow the schedule as closely as 

possible on the day of the hearing; 

however, please plan for the hearings to 

run either ahead of schedule or behind 

schedule. 

Each commenter will have 5 minutes 

to provide oral testimony. The EPA 

encourages commenters to provide the 

EPA with a copy of their oral testimony 

electronically (via email) by emailing it 

to topham.nathan@epa.gov. The EPA 

also recommends submitting the text of 

your oral testimony as written 

comments to the rulemaking docket. 

The EPA may ask clarifying questions 

during the oral presentations but will 

not respond to the presentations at that 

time. Written statements and supporting 

information submitted during the 

comment period will be considered 

with the same weight as oral testimony 

and supporting information presented at 

the public hearing. 

Please note that any updates made to 

any aspect of the hearing will be posted 

online at https://www.epa.gov/ 

stationary-sources-air-pollution/acetalresins-acrylic-modacrylic-fibers-carbonblack-hydrogen. While the EPA expects 

the hearing to go forward as set forth 

above, please monitor our website or 

contact the public hearing team at (888) 

372–8699 or by email at 

SPPDpublichearing@epa.gov to 

determine if there are any updates. The 

EPA does not intend to publish a 

document in the Federal Register 

announcing updates. 

If you require the services of a 

translator or a special accommodation 

such as audio description, please preregister for the hearing with the public 

hearing team and describe your needs 

by January 22, 2021. The EPA may not 

be able to arrange accommodations 

without advanced notice. 

Docket. The EPA has established a 

docket for this rulemaking under Docket 

ID No. EPA–HQ–OAR–2020–0532. All 

documents in the docket are listed in 

https://www.regulations.gov. Although 

listed, some information is not publicly 

available, e.g., Confidential Business 

Information (CBI) 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. With the 

exception of such material, publicly 

available docket materials are available 

electronically in Regulations.gov. 

Instructions. Direct your comments to 

Docket ID No. EPA–HQ–OAR–2020– 

0532. The EPA’s policy is that all 

comments received will be included in 

the public docket without change and 

may be made available online at https:// 

www.regulations.gov/, including any 

personal information provided, unless 

the comment includes information 

claimed to be CBI or other information 

whose disclosure is restricted by statute. 

Do not submit electronically any 

information that you consider to be CBI 

or other information whose disclosure is 

restricted by statute. This type of 

information should be submitted by 

mail as discussed below. 

The EPA may publish any comment 

received to its public docket. 

Multimedia submissions (audio, video, 

etc.) must be accompanied by a written 

comment. The written comment is 

considered the official comment and 

should include discussion of all points 

you wish to make. The EPA will 

generally not consider comments or 

comment contents located outside of the 

primary submission (i.e., on the Web, 

cloud, or other file sharing system). For 

additional submission methods, the full 

EPA public comment policy, 

information about CBI or multimedia 

submissions, and general guidance on 

making effective comments, please visit 

https://www.epa.gov/dockets/ 

commenting-epa-dockets. 

The https://www.regulations.gov/ 

website allows you to submit your 

comment anonymously, which means 

the EPA will not know your identity or 

contact information unless you provide 

it in the body of your comment. If you 

send an email comment directly to the 

EPA without going through https://

www.regulations.gov/, your email 

address will be automatically captured 

and included as part of the comment 

that is placed in the public docket and 

made available on the internet. If you 

submit an electronic comment, the EPA 

recommends that you include your 

name and other contact information in 

the body of your comment and with any 

digital storage media you submit. If the 

EPA cannot read your comment due to 

technical difficulties and cannot contact 

you for clarification, the EPA may not 

be able to consider your comment. 

Electronic files should not include 

special characters or any form of 

encryption and be free of any defects or 

viruses. For additional information 

about the EPA’s public docket, visit the 

EPA Docket Center homepage at https:// 

www.epa.gov/dockets. 

The EPA is temporarily suspending 

its Docket Center and Reading Room for 

public visitors, with limited exceptions, 

to reduce the risk of transmitting 

COVID–19. Our Docket Center staff will 

continue to provide remote customer 

service via email, phone, and webform. 

We encourage the public to submit 

comments via https://

www.regulations.gov/ as there may be a 

delay in processing mail and faxes. 

Hand deliveries or couriers will be 

received by scheduled appointment 

only. For further information and 

updates on EPA Docket Center services, 

please visit us online at https://

www.epa.gov/dockets. 

The EPA continues to carefully and 

continuously monitor information from 

the CDC, local area health departments, 

and our Federal partners so that we can 

respond rapidly as conditions change 

regarding COVID–19. 

Submitting CBI. Do not submit 

information containing CBI to the EPA 

through https://www.regulations.gov/ or 

email. Clearly mark the part or all of the 

information that you claim to be CBI. 

For CBI information on any digital 

storage media that you mail to the EPA, 

mark the outside of the digital storage 

media as CBI and then identify 

electronically within the digital storage 

media the specific information that is 

claimed as CBI. In addition to one 

complete version of the comments that 

includes information claimed as CBI, 

you must submit a copy of the 

comments that does not contain the 

information claimed as CBI directly to 

the public docket through the 

procedures outlined in Instructions 

above. If you submit any digital storage 

media that does not contain CBI, mark 

the outside of the digital storage media 

clearly that it does not contain CBI. 

Information not marked as CBI will be 

included in the public docket and the 

EPA’s electronic public docket without 

prior notice. Information marked as CBI 

will not be disclosed except in 

accordance with procedures set forth in 

40 Code of Federal Regulations (CFR) 

part 2. Send or deliver information 

identified as CBI only to the following 

address: OAQPS Document Control 

Officer (C404–02), OAQPS, U.S. 

Environmental Protection Agency, 

Research Triangle Park, North Carolina 

27711, Attention Docket ID No. EPA– 

HQ–OAR–2020–0532. Note that written 

comments containing CBI and 

submitted by mail may be delayed and 

no hand deliveries will be accepted. 

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 

3908 Federal Register / Vol. 86, No. 10 / Friday, January 15, 2021 / Proposed Rules 

reference purposes, the EPA defines the 

following terms and acronyms here: 

AEGL acute exposure guideline level 

AERMOD air dispersion model used by the 

HEM–3 model 

CAA Clean Air Act 

CalEPA California EPA 

CBI Confidential Business Information 

CFR Code of Federal Regulations 

EPA Environmental Protection Agency 

ERPG emergency response planning 

guideline 

ERT Electronic Reporting Tool 

HAP hazardous air pollutant(s) 

HCl hydrochloric acid 

HEM–3 Human Exposure Model, Version 

1.5.5 

HF hydrogen fluoride 

HI hazard index 

HQ hazard quotient 

IRIS Integrated Risk Information System 

km kilometer 

MACT maximum achievable control 

technology 

mg/kg-day milligrams per kilogram per day 

mg/m3 milligrams per cubic meter 

MIR maximum individual risk 

NAAQS National Ambient Air Quality 

Standards 

NAICS North American Industry 

Classification System 

NESHAP national emission standards for 

hazardous air pollutants 

NRC National Research Council 

OAQPS Office of Air Quality Planning and 

Standards 

OMB Office of Management and Budget 

PAH polycyclic aromatic hydrocarbons 

PB–HAP hazardous air pollutants known to 

be persistent and bio-accumulative in the 

environment 

PM particulate matter 

POM polycyclic organic matter 

ppm parts per million 

REL reference exposure level 

RFA Regulatory Flexibility Act 

RfC reference concentration 

RfD reference dose 

RTR residual risk and technology review 

SAB Science Advisory Board 

SBA Small Business Administration 

SSM startup, shutdown, and malfunction 

SV screening value 

TOSHI target organ-specific hazard index 

tpy tons per year 

TRIM.FaTE Total Risk Integrated 

Methodology.Fate, Transport, and 

Ecological Exposure model 

UF uncertainty factor 

mg/m3 microgram per cubic meter 

URE unit risk estimate 

VCS voluntary consensus standards 

Organization of this document. The 

information in this preamble is 

organized as follows: 

I. General Information 

A. Does this action apply to me? 

B. Where can I get a copy of this document 

and other related information? 

II. Background 

A. What is the statutory authority for this 

action? 

B. What is this source category and how 

does the current NESHAP regulate its 

HAP emissions? 

C. What data collection activities were 

conducted to support this action? 

D. What other relevant background 

information and data are available? 

III. Analytical Procedures and DecisionMaking 

A. How do we consider risk in our 

decision-making? 

B. How do we perform the technology 

review? 

C. How do we estimate post-MACT risk 

posed by the source category? 

IV. Analytical Results and Proposed 

Decisions 

A. What actions are we taking pursuant to 

CAA sections 112(d)(2) and 112(d)(3)? 

B. What are the results of the risk 

assessment and analyses? 

C. What are our proposed decisions 

regarding risk acceptability, ample 

margin of safety, and adverse 

environmental effect? 

D. What are the results and proposed 

decisions based on our technology 

review? 

E. What other actions are we proposing? 

F. What compliance dates are we 

proposing? 

V. Summary of Cost, Environmental, and 

Economic Impacts 

A. What are the affected sources? 

B. What are the air quality impacts? 

C. What are the cost impacts? 

D. What are the economic impacts? 

E. What are the benefits? 

VI. Request for Comments 

VII. Submitting Data Corrections 

VIII. Statutory and Executive Order Reviews 

A. Executive Order 12866: Regulatory 

Planning and Review and Executive 

Order 13563: Improving Regulation and 

Regulatory Review 

B. Executive Order 13771: Reducing 

Regulations and Controlling Regulatory 

Costs 

C. Paperwork Reduction Act (PRA) 

D. Regulatory Flexibility Act (RFA) 

E. Unfunded Mandates Reform Act 

(UMRA) 

F. Executive Order 13132: Federalism 

G. Executive Order 13175: Consultation 

and Coordination With Indian Tribal 

Governments 

H. Executive Order 13045: Protection of 

Children From Environmental Health 

Risks and Safety Risks 

I. Executive Order 13211: Actions 

Concerning Regulations That 

Significantly Affect Energy Supply, 

Distribution, or Use 

J. National Technology Transfer and 

Advancement Act (NTTAA) 

K. Executive Order 12898: Federal Actions 

To Address Environmental Justice in 

Minority Populations and Low-Income 

Populations 

I. General Information 

A. Does this action apply to me? 

The source category that is the subject 

of this proposal is cyanide chemicals 

manufacturing major sources regulated 

under 40 CFR 63, subpart YY. The 

North American Industry Classification 

System (NAICS) codes for the cyanide 

chemicals manufacturing industry are 

325188 and 325199. This list of 

categories and NAICS codes is not 

intended to be exhaustive, but rather 

provides a guide for readers regarding 

the entities that this proposed action is 

likely to affect. The proposed standards, 

once promulgated, will be directly 

applicable to the affected sources. 

Federal, state, local, and tribal 

government entities would not be 

affected by this proposed action. As 

defined in the Initial List of Categories 

of Sources Under Section 112(c)(1) of 

the Clean Air Act Amendments of 1990 

(see 57 FR 31576, July 16, 1992) and 

Documentation for Developing the 

Initial Source Category List, Final 

Report (see EPA–450/3–91–030, July 

1992), the Cyanide Chemicals 

Manufacturing source category is any 

facility engaged in the production of 

hydrogen cyanide or sodium cyanide. 

Hydrogen cyanide production includes, 

but is not limited to, production of 

hydrogen cyanide using any of the 

following methods: Reaction of methane 

and ammonia over a platinum catalyst, 

reaction of methane and ammonia over 

a platinum-rhodium catalyst, coproduction with acrylonitrile (via Sohio 

process), or pyrolysis of formaldehyde. 

Sodium cyanide production includes, 

but is not limited to, production of 

sodium cyanide via the neutralization 

process, or so-called wet process. In this 

process, hydrogen cyanide reacts with 

sodium hydroxide solution usually in a 

reactor that involves evaporation of 

water and crystallization of the product, 

commonly called white cyanide. 

B. 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 action 

is available on the internet. Following 

signature by the EPA Administrator, the 

EPA will post a copy of this proposed 

action at https://www.epa.gov/ 

stationary-sources-air-pollution/acetalresins-acrylic-modacrylic-fibers-carbonblack-hydrogen. Following publication 

in the Federal Register, the EPA will 

post the Federal Register version of the 

proposal and key technical documents 

at this same website. Information on the 

overall RTR program is available at 

https://www3.epa.gov/ttn/atw/rrisk/ 

rtrpg.html. 

The proposed changes to the CFR that 

would be necessary to incorporate the 

changes proposed in this action are set 

out in an attachment to the 

memorandum titled Proposed 

Regulation Edits for 40 CFR part 63, 

subpart YY, available in the docket for 

this action (Docket ID No. EPA–HQ– 

Federal Register / Vol. 86, No. 10 / Friday, January 15, 2021 / Proposed Rules 3909 

1Although defined as ‘‘maximum individual 

risk,’’ MIR refers only to cancer risk. MIR, one 

metric for assessing cancer risk, is the estimated 

risk if an individual were exposed to the maximum 

level of a pollutant for a lifetime. 

OAR–2020–0532). The document 

includes the specific proposed 

amendatory language for revising the 

CFR and, for the convenience of 

interested parties, a redline version of 

the regulation. Following signature by 

the EPA Administrator, the EPA will 

also post a copy of this memorandum 

and the attachments to https://

www.epa.gov/stationary-sources-airpollution/acetal-resins-acrylicmodacrylic-fibers-carbon-blackhydrogen. 

II. Background 

A. What is the statutory authority for 

this action? 

The statutory authority for this action 

is provided by sections 112 and 301 of 

the CAA, as amended (42 U.S.C. 7401 et 

seq.). Section 112 of the CAA 

establishes a two-stage regulatory 

process to develop standards for 

emissions of hazardous air pollutants 

(HAP) from stationary sources. 

Generally, the first stage involves 

establishing technology-based standards 

and the second stage involves 

evaluating those standards that are 

based on maximum achievable control 

technology (MACT) to determine 

whether additional standards are 

needed to address any remaining risk 

associated with HAP emissions. This 

second stage is commonly referred to as 

the ‘‘residual risk review.’’ In addition 

to the residual risk review, the CAA also 

requires the EPA to review standards set 

under CAA section 112 every 8 years 

and revise the standards as necessary 

taking into account any ‘‘developments 

in practices, processes, or control 

technologies.’’ This review is commonly 

referred to as the ‘‘technology review.’’ 

When the two reviews are combined 

into a single rulemaking, it is commonly 

referred to as the ‘‘risk and technology 

review.’’ The discussion that follows 

identifies the most relevant statutory 

sections and briefly explains the 

contours of the methodology used to 

implement these statutory requirements. 

A more comprehensive discussion 

appears in the document titled CAA 

Section 112 Risk and Technology 

Reviews: Statutory Authority and 

Methodology, in the docket for this 

rulemaking. 

In the first stage of the CAA section 

112 standard setting process, the EPA 

promulgates technology-based standards 

under CAA section 112(d) for categories 

of sources identified as emitting one or 

more of the HAP listed in CAA section 

112(b). Sources of HAP emissions are 

either major sources or area sources, and 

CAA section 112 establishes different 

requirements for major source standards 

and area source standards. ‘‘Major 

sources’’ are those that emit or have the 

potential to emit 10 tons per year (tpy) 

or more of a single HAP or 25 tpy or 

more of any combination of HAP. All 

other sources are ‘‘area sources.’’ For 

major sources, CAA section 112(d)(2) 

provides that the technology-based 

NESHAP must reflect the maximum 

degree of emission reductions of HAP 

achievable (after considering cost, 

energy requirements, and non-air 

quality health and environmental 

impacts). These standards are 

commonly referred to as MACT 

standards. CAA section 112(d)(3) also 

establishes a minimum control level for 

MACT standards, known as the MACT 

‘‘floor.’’ In certain instances, as 

provided in CAA section 112(h), the 

EPA may set work practice standards in 

lieu of numerical emission standards. 

The EPA must also consider control 

options that are more stringent than the 

floor. Standards more stringent than the 

floor are commonly referred to as 

beyond-the-floor standards. For area 

sources, CAA section 112(d)(5) gives the 

EPA discretion to set standards based on 

generally available control technologies 

or management practices (GACT 

standards) in lieu of MACT standards. 

The second stage in standard-setting 

focuses on identifying and addressing 

any remaining (i.e., ‘‘residual’’) risk 

pursuant to CAA section 112(f). For 

source categories subject to MACT 

standards, section 112(f)(2) of the CAA 

requires the EPA to determine whether 

promulgation of additional standards is 

needed to provide an ample margin of 

safety to protect public health or to 

prevent an adverse environmental 

effect. Section 112(d)(5) of the CAA 

provides that this residual risk review is 

not required for categories of area 

sources subject to GACT standards. 

Section 112(f)(2)(B) of the CAA further 

expressly preserves the EPA’s use of the 

two-step approach for developing 

standards to address any residual risk 

and the Agency’s interpretation of 

‘‘ample margin of safety’’ developed in 

the National Emissions Standards for 

Hazardous Air Pollutants: Benzene 

Emissions from Maleic Anhydride 

Plants, Ethylbenzene/Styrene Plants, 

Benzene Storage Vessels, Benzene 

Equipment Leaks, and Coke By-Product 

Recovery Plants (Benzene NESHAP) (54 

FR 38044, September 14, 1989). The 

EPA notified Congress in the Residual 

Risk Report that the Agency intended to 

use the Benzene NESHAP approach in 

making CAA section 112(f) residual risk 

determinations (EPA–453/R–99–001, p. 

ES–11). The EPA subsequently adopted 

this approach in its residual risk 

determinations and the United States 

Court of Appeals for the District of 

Columbia Circuit (the court) upheld the 

EPA’s interpretation that CAA section 

112(f)(2) incorporates the approach 

established in the Benzene NESHAP. 

See NRDC v. EPA, 529 F.3d 1077, 1083 

(D.C. Cir. 2008). 

The approach incorporated into the 

CAA and used by the EPA to evaluate 

residual risk and to develop standards 

under CAA section 112(f)(2) is a twostep approach. In the first step, the EPA 

determines whether risks are acceptable. 

This determination ‘‘considers all health 

information, including risk estimation 

uncertainty, and includes a presumptive 

limit on maximum individual lifetime 

[cancer] risk (MIR) 1 of approximately 1 

in 10 thousand.’’ (54 FR 38045). If risks 

are unacceptable, the EPA must 

determine the emissions standards 

necessary to reduce risk to an acceptable 

level without considering costs. In the 

second step of the approach, the EPA 

considers whether the emissions 

standards provide an ample margin of 

safety to protect public health ‘‘in 

consideration of all health information, 

including the number of persons at risk 

levels higher than approximately 1 in 1 

million, as well as other relevant factors, 

including costs and economic impacts, 

technological feasibility, and other 

factors relevant to each particular 

decision.’’ Id. The EPA must promulgate 

emission standards necessary to provide 

an ample margin of safety to protect 

public health or determine that the 

standards being reviewed provide an 

ample margin of safety without any 

revisions. After conducting the ample 

margin of safety analysis, we consider 

whether a more stringent standard is 

necessary to prevent, taking into 

consideration costs, energy, safety, and 

other relevant factors, an adverse 

environmental effect. 

CAA section 112(d)(6) separately 

requires the EPA to review standards 

promulgated under CAA section 112 

and revise them ‘‘as necessary (taking 

into account developments in practices, 

processes, and control technologies)’’ no 

less often than every 8 years. In 

conducting this review, which we call 

the ‘‘technology review,’’ the EPA is not 

required to recalculate the MACT floor. 

Natural Resources Defense Council 

(NRDC) v. EPA, 529 F.3d 1077, 1084 

(D.C. Cir. 2008). Association of Battery 

Recyclers, Inc. v. EPA, 716 F.3d 667 

(D.C. Cir. 2013). The EPA may consider 

cost in deciding whether to revise the 

3910 Federal Register / Vol. 86, No. 10 / Friday, January 15, 2021 / Proposed Rules 

2 ‘‘Dry end’’ process vents at sodium cyanide 

units must meet a 98 percent reduction 

performance standard for emissions of sodium 

cyanide since this is the form of cyanide 

compounds emitted from these emission points. 

The HAP emitted from other process vents that 

make up the ‘‘total HAP’’ emitted from these 

sources are hydrogen cyanide, acetonitrile, and 

acrylonitrile. 

3Transfer racks emissions limits are expressed in 

terms of hydrogen cyanide as this is the only HAP 

emitted from these sources. 

standards pursuant to CAA section 

112(d)(6). The EPA is required to 

address regulatory gaps, such as missing 

standards for listed air toxics known to 

be emitted from the source category. 

Louisiana Environmental Action 

Network (LEAN) v. EPA, 955 F.3d 1088 

(D.C. Cir. 2020). 

B. What is this source category and how 

does the current NESHAP regulate its 

HAP emissions? 

The MACT standards for the Cyanide 

Chemicals Manufacturing source 

category are contained in the Generic 

Maximum Achievable Control 

Technology (GMACT) NESHAP which 

also includes MACT standards for 

several other source categories. The 

cyanide chemicals manufacturing 

standards were promulgated on July 12, 

2002, (67 FR 46258) and codified at 40 

CFR part 63, subpart YY. As 

promulgated in 2002, the cyanide 

chemicals manufacturing standards 

regulate HAP emissions from cyanide 

chemicals manufacturing units located 

at major sources. The HAP emitted from 

the source category include cyanide 

compounds (hydrogen cyanide and 

sodium cyanide), acetonitrile, and 

acrylonitrile. 

The NESHAP defines the affected 

source as each cyanide chemicals 

manufacturing process unit (CCMPU). 

The rule states that the CCMPU is the 

equipment assembled and connected by 

hard-piping or duct work to process raw 

materials to manufacture, store, and 

transport a cyanide chemicals product. 

A CCMPU shall be limited to any one 

of the following: An Andrussow process 

unit, a Blausaure Methane Anlage 

process unit, a sodium cyanide process 

unit, or a Sohio hydrogen cyanide 

process unit. For the purpose of this 

subpart, a CCMPU includes reactors and 

associated unit operations, associated 

recovery devices, and any feed, 

intermediate and product storage 

vessels, product transfer racks, and 

connected ducts and piping. A CCMPU 

also includes pumps, compressors, 

agitators, pressure relief devices, 

sampling connection systems, openended valves or lines, valves, 

connectors, instrumentation systems, 

and control devices or systems. 

The NESHAP established emissions 

standards for process vents, storage 

vessels, transfer racks, and equipment 

leaks. Cyanide process vents are subject 

to a 98 weight-percent reduction of total 

HAP 2 performance standard or 20 parts 

per million by volume (ppmv) total HAP 

outlet exit concentration limit. For 

storage vessels in the Cyanide 

Chemicals Manufacturing source 

category, sources may either choose to 

comply with a 98 weight-percent 

reduction of hydrogen cyanide 

performance standard, a 20 ppmv 

hydrogen cyanide exit outlet 

concentration limit, or equipment 

standards (e.g., use a flare). Transfer 

racks are subject to equipment standards 

or the same performance standard or 

concentration limit 3 as cyanide process 

vents. Equipment leaks are subject to 

work practice standards required by 

either 40 CFR part 63, subpart TT or 

subpart UU. 

C. What data collection activities were 

conducted to support this action? 

The EPA used a variety of resources 

to obtain data about facilities and their 

emissions for use in our risk assessment. 

We used the EPA’s Enforcement and 

Compliance History Online (ECHO) 

database to develop a list of potentially 

subject facilities. Using this list, we 

searched state environmental agency 

websites and correspondence with 

industry to obtain copies of title V 

permits to confirm whether facilities 

have cyanide chemicals manufacturing 

subject to the NESHAP. Once the 

facility list was finalized, the EPA used 

the 2017 National Emissions Inventory 

(NEI) to get emissions data for each 

facility. We compared the NEI data to 

title V permits to provide additional 

information regarding the applicability 

of the Cyanide Chemicals 

Manufacturing NESHAP. Further 

discussion of the methodology used to 

develop the emissions dataset for the 

risk assessment can be found in the 

memorandum titled Technical Support 

Document for the Cyanide Chemicals 

Manufacturing NESHAP Residual Risk 

and Technology Review Proposal, which 

is available in the docket for this action. 

D. What other relevant background 

information and data are available? 

We searched for information from the 

Reasonably Available Control 

Technology, Best Available Control 

Technology, and Lowest Achievable 

Emission Rate Clearinghouse (RBLC) 

database, reviewed title V permits for 

each cyanide chemicals manufacturing 

facility, and reviewed regulatory actions 

related to emissions controls at similar 

sources that could be applicable to 

cyanide chemicals manufacturing. We 

reviewed the RBLC to identify potential 

additional control technologies. No 

additional control technologies 

applicable to cyanide chemicals 

manufacturing were found using the 

RBLC. Additional information related to 

the promulgation and subsequent 

amendments of the NESHAP is available 

in docket ID: No. EPA–HQ–OAR–2004– 

0041. 

III. Analytical Procedures and 

Decision-Making 

In this section, we describe the 

analyses performed to support the 

proposed decisions for the RTR and 

other issues addressed in this proposal. 

A. How do we consider risk in our 

decision-making? 

As discussed in section II.A of this 

preamble and in the Benzene NESHAP, 

in evaluating and developing standards 

under CAA section 112(f)(2), we apply 

a two-step approach to determine 

whether or not risks are acceptable and 

to determine if the standards provide an 

ample margin of safety to protect public 

health. As explained in the Benzene 

NESHAP, ‘‘the first step judgment on 

acceptability cannot be reduced to any 

single factor’’ and, thus, ‘‘[t]he 

Administrator believes that the 

acceptability of risk under section 112 is 

best judged on the basis of a broad set 

of health risk measures and 

information.’’ (54 FR at 38046). 

Similarly, with regard to the ample 

margin of safety determination, ‘‘the 

Agency again considers all of the health 

risk and other health information 

considered in the first step. Beyond that 

information, additional factors relating 

to the appropriate level of control will 

also be considered, including cost and 

economic impacts of controls, 

technological feasibility, uncertainties, 

and any other relevant factors.’’ Id. 

The Benzene NESHAP approach 

provides flexibility regarding factors the 

EPA may consider in making 

determinations and how the EPA may 

weigh those factors for each source 

category. The EPA conducts a risk 

assessment that provides estimates of 

the MIR posed by emissions of HAP that 

are carcinogens from each source in the 

source category, the hazard index (HI) 

for chronic exposures to HAP with the 

potential to cause noncancer health 

effects, and the hazard quotient (HQ) for 

acute exposures to HAP with the 

potential to cause noncancer health 

Federal Register / Vol. 86, No. 10 / Friday, January 15, 2021 / Proposed Rules 3911 

4The MIR is defined as the cancer risk associated 

with a lifetime of exposure at the highest 

concentration of HAP where people are likely to 

live. The HQ is the ratio of the potential HAP 

exposure concentration to the noncancer doseresponse value; the HI is the sum of HQs for HAP 

that affect the same target organ or organ system. 

5Recommendations of the SAB Risk and 

Technology Review Methods Panel are provided in 

their report, which is available at: https://

yosemite.epa.gov/sab/sabproduct.nsf/4AB3966

E263D943A8525771F00668381/$File/EPA-SAB-10- 

007-unsigned.pdf. 

effects.4 The assessment also provides 

estimates of the distribution of cancer 

risk within the exposed populations, 

cancer incidence, and an evaluation of 

the potential for an adverse 

environmental effect. The scope of the 

EPA’s risk analysis is consistent with 

the explanation in EPA’s response to 

comments on our policy under the 

Benzene NESHAP: 

The policy chosen by the Administrator 

permits consideration of multiple measures 

of health risk. Not only can the MIR figure 

be considered, but also incidence, the 

presence of non-cancer health effects, and the 

uncertainties of the risk estimates. In this 

way, the effect on the most exposed 

individuals can be reviewed as well as the 

impact on the general public. These factors 

can then be weighed in each individual case. 

This approach complies with the Vinyl 

Chloride mandate that the Administrator 

ascertain an acceptable level of risk to the 

public by employing his expertise to assess 

available data. It also complies with the 

Congressional intent behind the CAA, which 

did not exclude the use of any particular 

measure of public health risk from the EPA’s 

consideration with respect to CAA section 

112 regulations, and thereby implicitly 

permits consideration of any and all 

measures of health risk which the 

Administrator, in his judgment, believes are 

appropriate to determining what will 

‘‘protect the public health. 

(54 FR at 38057). Thus, the level of the 

MIR is only one factor to be weighed in 

determining acceptability of risk. The 

Benzene NESHAP explained that ‘‘an 

MIR of approximately one in 10 

thousand should ordinarily be the upper 

end of the range of acceptability. As 

risks increase above this benchmark, 

they become presumptively less 

acceptable under CAA section 112, and 

would be weighed with the other health 

risk measures and information in 

making an overall judgment on 

acceptability. Or, the Agency may find, 

in a particular case, that a risk that 

includes an MIR less than the 

presumptively acceptable level is 

unacceptable in the light of other health 

risk factors.’’ Id. at 38045. In other 

words, risks that include an MIR above 

100-in-1 million may be determined to 

be acceptable, and risks with an MIR 

below that level may be determined to 

be unacceptable, depending on all of the 

available health information. Similarly, 

with regard to the ample margin of 

safety analysis, the EPA stated in the 

Benzene NESHAP that: ‘‘EPA believes 

the relative weight of the many factors 

that can be considered in selecting an 

ample margin of safety can only be 

determined for each specific source 

category. This occurs mainly because 

technological and economic factors 

(along with the health-related factors) 

vary from source category to source 

category.’’ Id. at 38061. We also 

consider the uncertainties associated 

with the various risk analyses, as 

discussed earlier in this preamble, in 

our determinations of acceptability and 

ample margin of safety. 

The EPA notes that it has not 

considered certain health information to 

date in making residual risk 

determinations. At this time, we do not 

attempt to quantify the HAP risk that 

may be associated with emissions from 

other facilities that do not include the 

source category under review, mobile 

source emissions, natural source 

emissions, persistent environmental 

pollution, or atmospheric 

transformation in the vicinity of the 

sources in the category. 

The EPA understands the potential 

importance of considering an 

individual’s total exposure to HAP in 

addition to considering exposure to 

HAP emissions from the source category 

and facility. We recognize that such 

consideration may be particularly 

important when assessing noncancer 

risk, where pollutant-specific exposure 

health reference levels (e.g., reference 

concentrations (RfCs)) are based on the 

assumption that thresholds exist for 

adverse health effects. For example, the 

EPA recognizes that, although exposures 

attributable to emissions from a source 

category or facility alone may not 

indicate the potential for increased risk 

of adverse noncancer health effects in a 

population, the exposures resulting 

from emissions from the facility in 

combination with emissions from all of 

the other sources (e.g., other facilities) to 

which an individual is exposed may be 

sufficient to result in an increased risk 

of adverse noncancer health effects. In 

May 2010, the Science Advisory Board 

(SAB) advised the EPA ‘‘that RTR 

assessments will be most useful to 

decision makers and communities if 

results are presented in the broader 

context of aggregate and cumulative 

risks, including background 

concentrations and contributions from 

other sources in the area.’’ 5

In response to the SAB 

recommendations, the EPA incorporates 

cumulative risk analyses into its RTR 

risk assessments. The Agency (1) 

conducts facility-wide assessments, 

which include source category emission 

points, as well as other emission points 

within the facilities; (2) combines 

exposures from multiple sources in the 

same category that could affect the same 

individuals; and (3) for some persistent 

and bioaccumulative pollutants, 

analyzes the ingestion route of 

exposure. In addition, the RTR risk 

assessments consider aggregate cancer 

risk from all carcinogens and aggregated 

noncancer HQs for all noncarcinogens 

affecting the same target organ or target 

organ system. 

Although we are interested in placing 

source category and facility-wide HAP 

risk in the context of total HAP risk 

from all sources combined in the 

vicinity of each source, we are 

concerned about the uncertainties of 

doing so. Estimates of total HAP risk 

from emission sources other than those 

that we have studied in depth during 

this RTR review would have 

significantly greater associated 

uncertainties than the source category or 

facility-wide estimates. Such aggregate 

or cumulative assessments would 

compound those uncertainties, making 

the assessments too unreliable. 

B. How do we perform the technology 

review? 

Our technology review primarily 

focuses on the identification and 

evaluation of developments in practices, 

processes, and control technologies that 

have occurred since the MACT 

standards were promulgated. Where we 

identify such developments, we analyze 

their technical feasibility, estimated 

costs, energy implications, and non-air 

environmental impacts. We also 

consider the emission reductions 

associated with applying each 

development. This analysis informs our 

decision of whether it is ‘‘necessary’’ to 

revise the emissions standards. In 

addition, we consider the 

appropriateness of applying controls to 

new sources versus retrofitting existing 

sources. For this exercise, we consider 

any of the following to be a 

‘‘development’’: 

• Any add-on control technology or 

other equipment that was not identified 

and considered during development of 

the original MACT standards; 

• Any improvements in add-on 

control technology or other equipment 

(that were identified and considered 

during development of the original 

MACT standards) that could result in 

additional emissions reduction; 

• Any work practice or operational 

procedure that was not identified or 

3912 Federal Register / Vol. 86, No. 10 / Friday, January 15, 2021 / Proposed Rules 

6U.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. 

considered during development of the 

original MACT standards; 

• Any process change or pollution 

prevention alternative that could be 

broadly applied to the industry and that 

was not identified or considered during 

development of the original MACT 

standards; and 

• Any significant changes in the cost 

(including cost effectiveness) of 

applying controls (including controls 

the EPA considered during the 

development of the original MACT 

standards). 

In addition to reviewing the practices, 

processes, and control technologies that 

were considered at the time we 

originally developed (or last updated) 

the NESHAP, we review a variety of 

data sources in our investigation of 

potential practices, processes, or 

controls. We also review the NESHAP 

and the available data to determine if 

there are any unregulated emissions of 

HAP within the source category and 

evaluate this data for use in developing 

new emission standards. See sections 

II.C and II.D of this preamble for 

information on the specific data sources 

that were reviewed as part of the 

technology review. 

C. How do we estimate post-MACT risk 

posed by the source category? 

In this section, we provide a complete 

description of the types of analyses that 

we generally perform during the risk 

assessment process. In some cases, we 

do not perform a specific analysis 

because it is not relevant. For example, 

in the absence of emissions of HAP 

known to be persistent and 

bioaccumulative in the environment 

(PB–HAP), we would not perform a 

multipathway exposure assessment. 

Where we do not perform an analysis, 

we state that we do not and provide the 

reason. While we present all of our risk 

assessment methods, we only present 

risk assessment results for the analyses 

actually conducted (see section IV.B of 

this preamble). 

The EPA conducts a risk assessment 

that provides estimates of the MIR for 

cancer posed by the HAP emissions 

from each source in the source category, 

the HI for chronic exposures to HAP 

with the potential to cause noncancer 

health effects, and the HQ for acute 

exposures to HAP with the potential to 

cause noncancer health effects. The 

assessment also provides estimates of 

the distribution of cancer risk within the 

exposed populations, cancer incidence, 

and an evaluation of the potential for an 

adverse environmental effect. The seven 

sections that follow this paragraph 

describe how we estimated emissions 

and conducted the risk assessment. The 

docket for this rulemaking contains the 

following document which provides 

more information on the risk assessment 

inputs and models: Residual Risk 

Assessment for the Cyanide Chemicals 

Manufacturing Source Category in 

Support of the 2020 Risk and 

Technology Review Proposed Rule. The 

methods used to assess risk (as 

described in the seven primary steps 

below) are consistent with those 

described by the EPA in the document 

reviewed by a panel of the EPA’s SAB 

in 2009; 6 and described in the SAB 

review report issued in 2010. They are 

also consistent with the key 

recommendations contained in that 

report. 

1. How did we estimate actual 

emissions and identify the emissions 

release characteristics? 

The list of facilities subject to the 

NESHAP was created through searching 

the EPA’s ECHO database, the 2017 NEI, 

and state databases of title V permits. 

The list of facilities is available in the 

memorandum titled Technical Support 

Document for the Cyanide Chemicals 

Manufacturing NESHAP Residual Risk 

and Technology Review Proposal. Once 

the facility list was finalized, available 

emissions data were obtained from the 

NEI. Title V permits were used to 

determine which emission points at 

each facility are subject to the Cyanide 

Chemicals Manufacturing NESHAP. 

We compared the NEI data to title V 

permits to confirm that the NEI 

included all emission points listed as 

subject to the NESHAP according to the 

permit. We evaluated latitudes and 

longitudes listed in the NEI to ensure 

their accuracy using satellite imagery. 

All of the latitudes and longitudes used 

in our dispersion modeling are in the 

modeling file used for the proposed 

rule, which is available in Docket ID No. 

EPA–HQ–OAR–2020–0532. Corrections 

were made to emission point 

characteristics for one non-category 

emission point that appeared to have 

erroneous stack velocity entered into the 

NEI. This emission point’s stack 

velocity was corrected to a default 

maximum value. All corrections made 

to emission point parameters are 

documented in the modeling file, 

available in Docket ID No. EPA–HQ– 

OAR–2020–0532. 

2. How did we estimate MACTallowable emissions? 

The available emissions data in the 

RTR emissions dataset include estimates 

of the mass of HAP emitted during a 

specified annual time period. These 

‘‘actual’’ emission levels are often lower 

than the emission levels allowed under 

the requirements of the current MACT 

standards. The emissions allowed under 

the MACT standards are referred to as 

the ‘‘MACT-allowable’’ emissions. We 

discussed the consideration of both 

MACT-allowable and actual emissions 

in the final Coke Oven Batteries RTR (70 

FR 19992, 19998 and 19999, April 15, 

2005) and in the proposed and final 

Hazardous Organic NESHAP RTR (71 

FR 34421, 34428, June 14, 2006, and 71 

FR 76603, 76609, December 21, 2006, 

respectively). In those actions, we noted 

that assessing the risk at the MACTallowable level is inherently reasonable 

since that risk reflects the maximum 

level facilities could emit and still 

comply with national emission 

standards. We also explained that it is 

reasonable to consider actual emissions, 

where such data are available, in both 

steps of the risk analysis, in accordance 

with the Benzene NESHAP approach. 

(54 FR 38044). 

We have determined that the actual 

emissions data are reasonable estimates 

of the MACT-allowable emissions levels 

for the Cyanide Chemicals 

Manufacturing source category. The 

ability to estimate MACT-allowable 

emissions from the actual emissions 

dataset is largely dependent on the 

format of the standard for a given 

emissions source as well as the types of 

controls employed for the source. With 

respect to the various types of controls 

used within the Cyanide Chemicals 

Manufacturing source category, the most 

prevalent is the use of a flare as a 

combustion control device. A flare can 

be used to control emissions for a single 

emissions source, or, as is generally the 

case, to control emissions from multiple 

emission sources/emission source types. 

Flares are designed to handle a wide 

range of flowrates and compositions of 

combustible waste gases. Within the 

Cyanide Chemicals Manufacturing 

source category, flares generally control 

emissions from multiple emission 

source types. Consideration of this, 

along with not having a specific limit on 

how much gas can be combusted in a 

flare (given that in many cases multiple 

emissions sources are being controlled 

by this control device), means that it is 

extremely difficult to determine an 

allowable emission rate for flares. We 

have determined that flares in the 

Cyanide Chemicals Manufacturing 

Federal Register / Vol. 86, No. 10 / Friday, January 15, 2021 / Proposed Rules 3913 

7For more information about HEM–3, go to 

https://www.epa.gov/fera/risk-assessment-andmodeling-human-exposure-model-hem. 

8U.S. EPA. Revision to the Guideline on Air 

Quality Models: Adoption of a Preferred General 

Purpose (Flat and Complex Terrain) Dispersion 

Model and Other Revisions (70 FR 68218, 

November 9, 2005). 

9A census block is the smallest geographic area 

for which census statistics are tabulated. 

source category are currently complying 

with design and operational 

requirements that are generally expected 

to achieve 98 percent destruction 

efficiencies or control, which is the 

level of control required by the 

NESHAP. HAP emissions inventories 

for flares in the Cyanide Chemicals 

Manufacturing source category are 

developed using engineering knowledge 

and, in many instances, presume this 98 

percent level of control. The Agency is 

unaware of any data that suggest that 

flares used as controls in the Cyanide 

Chemicals Manufacturing source 

category are consistently overcontrolling 

HAP emissions beyond 98 percent 

control. Thus, weighing all of these 

factors for flares, we determined that the 

actual emission levels are a reasonable 

estimation of the MACT-allowable 

emissions levels where the performance 

standards allow the use of a flare as an 

air pollution control device (e.g., storage 

vessels, process vents, and transfer 

racks). 

For equipment leaks, which are 

currently subject to work practice 

standards, there would be no difference 

between actual and MACT-allowable 

emissions for facilities in the Cyanide 

Chemicals Manufacturing source 

category, provided the facilities are 

complying with the MACT standards as 

well as not conducting additional work 

practices that would reduce emissions 

beyond those required by the rule. We 

are aware of only one rule in the state 

of Texas, the Texas Commission of 

Environmental Quality (TCEQ) Highly 

Reactive Volatile Organic Compounds 

(HRVOC) Rule (i.e., 30 TAC Chapter 

115, Subchapter H, Division 3), that may 

contain more stringent leak definitions 

and/or monitoring frequencies for 

certain pieces of equipment for the three 

facilities located in Texas that might be 

subject to this rule. However, based on 

our review of the Texas rule, we note 

the following: (1) Specific facilities 

located in the Houston-GalvestonBrazoria area still conduct a leak 

detection and repair (LDAR) program 

using EPA Method 21; (2) the vast 

majority of equipment, including almost 

all pieces of equipment in gas and vapor 

service that would tend to contribute 

considerably to the overall equipment 

leak air emissions, are complying with 

the same leak definition as in the MACT 

standards; and (3) the TCEQ HRVOC 

Rule generally requires quarterly 

monitoring while the MACT standards 

have varying monitoring frequencies 

depending on the percentage of leaking 

equipment that could lead to more 

stringent, the same, or less stringent 

frequencies that would require an EPA 

Method 21 measurement and repair of a 

leaking component (if measured). 

Therefore, considering these factors for 

equipment leaks, we determined that 

the actual emission levels for equipment 

leaks are a reasonable estimation of the 

MACT-allowable emissions levels. 

3. How do we conduct dispersion 

modeling, determine inhalation 

exposures, and estimate individual and 

population inhalation risk? 

Both long-term and short-term 

inhalation exposure concentrations and 

health risk from the source category 

addressed in this proposal were 

estimated using the Human Exposure 

Model (HEM–3).7 The HEM–3 performs 

three primary risk assessment activities: 

(1) Conducting dispersion modeling to 

estimate the concentrations of HAP in 

ambient air, (2) estimating long-term 

and short-term inhalation exposures to 

individuals residing within 50 

kilometers (km) of the modeled sources, 

and (3) estimating individual and 

population-level inhalation risk using 

the exposure estimates and quantitative 

dose-response information. 

a. Dispersion Modeling 

The air dispersion model AERMOD, 

used by the HEM–3 model, is one of the 

EPA’s preferred models for assessing air 

pollutant concentrations from industrial 

facilities.8 To perform the dispersion 

modeling and to develop the 

preliminary risk estimates, HEM–3 

draws on three data libraries. The first 

is a library of meteorological data, 

which is used for dispersion 

calculations. This library includes 1 

year (2016) of hourly surface and upper 

air observations from 826 

meteorological stations, selected to 

provide coverage of the United States 

and Puerto Rico. A second library of 

United States Census Bureau census 

block 9 internal point locations and 

populations provides the basis of 

human exposure calculations (U.S. 

Census, 2010). In addition, for each 

census block, the census library 

includes the elevation and controlling 

hill height, which are also used in 

dispersion calculations. A third library 

of pollutant-specific dose-response 

values is used to estimate health risk. 

These are discussed below. 

b. Risk From Chronic Exposure to HAP 

In developing the risk assessment for 

chronic exposures, we use the estimated 

annual average ambient air 

concentrations of each HAP emitted by 

each source in the source category. The 

HAP air concentrations at each nearby 

census block centroid located within 50 

km of the facility are a surrogate for the 

chronic inhalation exposure 

concentration for all the people who 

reside in that census block. A distance 

of 50 km is consistent with both the 

analysis supporting the 1989 Benzene 

NESHAP (54 FR 38044) and the 

limitations of Gaussian dispersion 

models, including AERMOD. 

For each facility, we calculate the MIR 

as the cancer risk associated with a 

continuous lifetime (24 hours per day, 

7 days per week, 52 weeks per year, 70 

years) exposure to the maximum 

concentration at the centroid of each 

inhabited census block. We calculate 

individual cancer risk by multiplying 

the estimated lifetime exposure to the 

ambient concentration of each HAP (in 

micrograms per cubic meter (mg/m3)) by 

its unit risk estimate (URE). The URE is 

an upper-bound estimate of an 

individual’s incremental risk of 

contracting cancer over a lifetime of 

exposure to a concentration of 1 

microgram of the pollutant per cubic 

meter of air. For residual risk 

assessments, we generally use UREs 

from the EPA’s Integrated Risk 

Information System (IRIS). For 

carcinogenic pollutants without IRIS 

values, we look to other reputable 

sources of cancer dose-response values, 

often using California EPA (CalEPA) 

UREs, where available. In cases where 

new, scientifically credible doseresponse values have been developed in 

a manner consistent with EPA 

guidelines and have undergone a peer 

review process similar to that used by 

the EPA, we may use such doseresponse values in place of, or in 

addition to, other values, if appropriate. 

The pollutant-specific dose-response 

values used to estimate health risk are 

available at https://www.epa.gov/fera/ 

dose-response-assessment-assessinghealth-risks-associated-exposurehazardous-air-pollutants. 

No data are available on the 

carcinogenic effects of cyanide 

compounds in humans via inhalation. 

Under the U.S. EPA (2005a) Guidelines 

for Carcinogen Risk Assessment, there is 

‘‘inadequate information to assess the 

carcinogenic potential’’ of cyanide 

compounds. 

To estimate individual lifetime cancer 

risks associated with exposure to HAP 

emissions from each facility in the 

3914 Federal Register / Vol. 86, No. 10 / Friday, January 15, 2021 / Proposed Rules 

10The EPA’s 2005 Guidelines for Carcinogen Risk 

Assessment classifies carcinogens as: ‘‘carcinogenic 

to humans,’’ ‘‘likely to be carcinogenic to humans,’’ 

and ‘‘suggestive evidence of carcinogenic 

potential.’’ These classifications also coincide with 

the terms ‘‘known carcinogen, probable carcinogen, 

and possible carcinogen,’’ respectively, which are 

the terms advocated in the EPA’s Guidelines for 

Carcinogen Risk Assessment, published in 1986 (51 

FR 33992, September 24, 1986). In August 2000, the 

document, Supplemental Guidance for Conducting 

Health Risk Assessment of Chemical Mixtures 

(EPA/630/R–00/002), was published as a 

supplement to the 1986 document. Copies of both 

documents can be obtained from https:// 

cfpub.epa.gov/ncea/risk/recordisplay.cfm?

deid=20533&CFID=70315376&CFTOKEN=

71597944. Summing the risk of these individual 

compounds to obtain the cumulative cancer risk is 

an approach that was recommended by the EPA’s 

SAB in their 2002 peer review of the EPA’s National 

Air Toxics Assessment (NATA) titled NATA— 

Evaluating the National-scale Air Toxics 

Assessment 1996 Data—an SAB Advisory, available 

at https://yosemite.epa.gov/sab/sabproduct.nsf/ 

214C6E915BB04E14852570CA007A682C/$File/ 

ecadv02001.pdf. 

11See, e.g., U.S. EPA. Screening Methodologies to 

Support Risk and Technology Reviews (RTR): A 

Case Study Analysis (Draft Report, May 2017. 

https://www3.epa.gov/ttn/atw/rrisk/rtrpg.html). 

12 In the absence of hourly emission data, we 

develop estimates of maximum hourly emission 

rates by multiplying the average actual annual 

emissions rates by a factor (either a categoryspecific factor or a default factor of 10) to account 

for variability. This is documented in Residual Risk 

Assessment for the Cyanide Chemicals 

Manufacturing Source Category in Support of the 

2020 Risk and Technology Review Proposed Rule 

and in Appendix 5 of the report: Technical Support 

Document for Acute Risk Screening Assessment. 

Both are available in the docket for this rulemaking. 

source category, we sum the risks for 

each of the carcinogenic HAP 10 emitted 

by the modeled facility. We estimate 

cancer risk at every census block within 

50 km of every facility in the source 

category. The MIR is the highest 

individual lifetime cancer risk estimated 

for any of those census blocks. In 

addition to calculating the MIR, we 

estimate the distribution of individual 

cancer risks for the source category by 

summing the number of individuals 

within 50 km of the sources whose 

estimated risk falls within a specified 

risk range. We also estimate annual 

cancer incidence by multiplying the 

estimated lifetime cancer risk at each 

census block by the number of people 

residing in that block, summing results 

for all of the census blocks, and then 

dividing this result by a 70-year 

lifetime. 

To assess the risk of noncancer health 

effects from chronic exposure to HAP, 

we calculate either an HQ or a target 

organ-specific hazard index (TOSHI). 

We calculate an HQ when a single 

noncancer HAP is emitted. Where more 

than one noncancer HAP is emitted, we 

sum the HQ for each of the HAP that 

affects a common target organ or target 

organ system to obtain a TOSHI. The 

HQ is the estimated exposure divided 

by the chronic noncancer dose-response 

value, which is a value selected from 

one of several sources. The preferred 

chronic noncancer dose-response value 

is the EPA RfC, defined as ‘‘an estimate 

(with uncertainty spanning perhaps an 

order of magnitude) of a continuous 

inhalation exposure to the human 

population (including sensitive 

subgroups) that is likely to be without 

an appreciable risk of deleterious effects 

during a lifetime’’ (https://

iaspub.epa.gov/sor_internet/registry/ 

termreg/searchandretrieve/ 

glossariesandkeywordlists/ 

search.do?details=&vocabName=

IRIS%20Glossary). In cases where an 

RfC from the EPA’s IRIS is not available 

or where the EPA determines that using 

a value other than the RfC is 

appropriate, the chronic noncancer 

dose-response value can be a value from 

the following prioritized sources, which 

define their dose-response values 

similarly to the EPA: (1) The Agency for 

Toxic Substances and Disease Registry 

(ATSDR) Minimum Risk Level (https:// 

www.atsdr.cdc.gov/mrls/index.asp); (2) 

the CalEPA Chronic Reference Exposure 

Level (REL) (https://oehha.ca.gov/air/ 

crnr/notice-adoption-air-toxics-hotspots-program-guidance-manualpreparation-health-risk-0); or (3) as 

noted above, a scientifically credible 

dose-response value that has been 

developed in a manner consistent with 

the EPA guidelines and has undergone 

a peer review process similar to that 

used by the EPA. The pollutant-specific 

dose-response values used to estimate 

health risks are available at https://

www.epa.gov/fera/dose-responseassessment-assessing-health-risksassociated-exposure-hazardous-airpollutants. 

Cyanide is extremely toxic to humans. 

Acute (10-minute) inhalation exposure 

to 579 milligrams per cubic meter (mg/ 

m3) of hydrogen cyanide will cause 

death in 50 percent of exposed humans. 

Nonlethal exposures to hydrogen 

cyanide gas will cause a variety of 

effects in humans, such as headache, 

dizziness, upper respiratory irritation, 

cough, altered sense of smell, nasal 

congestion, nosebleed, and difficulty 

breathing. Chronic (long-term) 

inhalation exposure of humans to 

cyanide results primarily in effects on 

the central nervous system. Other effects 

in humans include cardiovascular and 

respiratory effects, effects to the 

endocrine system (e.g., thyroid 

enlargement, altered iodine uptake), and 

irritation to the eyes and skin. However, 

short term exposure levels below the 

acute REL and chronic exposures below 

the RfC are not likely to cause adverse 

effects. 

c. Risk From Acute Exposure to HAP 

That May Cause Health Effects Other 

Than Cancer 

For each HAP for which appropriate 

acute inhalation dose-response values 

are available, the EPA also assesses the 

potential health risks due to acute 

exposure. For these assessments, the 

EPA makes conservative assumptions 

about emission rates, meteorology, and 

exposure location. As part of our efforts 

to continually improve our 

methodologies to evaluate the risks that 

HAP emitted from categories of 

industrial sources pose to human health 

and the environment,11 we revised our 

treatment of meteorological data to use 

reasonable worst-case air dispersion 

conditions in our acute risk screening 

assessments instead of worst-case air 

dispersion conditions. This revised 

treatment of meteorological data and the 

supporting rationale are described in 

more detail in Residual Risk Assessment 

for the Cyanide Chemicals 

Manufacturing Source Category in 

Support of the 2020 Risk and 

Technology Review Proposed Rule and 

in Appendix 5 of the report: Technical 

Support Document for Acute Risk 

Screening Assessment. This revised 

approach has been used in this 

proposed rule and in all other RTR 

rulemakings proposed on or after June 3, 

2019. 

To assess the potential acute risk to 

the maximally exposed individual, we 

use the peak hourly emission rate for 

each emission point,12 reasonable 

worst-case air dispersion conditions 

(i.e., 99th percentile), and the point of 

highest off-site exposure. Specifically, 

we assume that peak emissions from the 

source category and reasonable worstcase air dispersion conditions co-occur 

and that a person is present at the point 

of maximum exposure. 

To characterize the potential health 

risks associated with estimated acute 

inhalation exposures to a HAP, we 

generally use multiple acute doseresponse values, including acute RELs, 

acute exposure guideline levels 

(AEGLs), and emergency response 

planning guidelines (ERPG) for 1-hour 

exposure durations, if available, to 

calculate acute HQs. The acute HQ is 

calculated by dividing the estimated 

acute exposure concentration by the 

acute dose-response value. For each 

HAP for which acute dose-response 

values are available, the EPA calculates 

acute HQs. 

An acute REL is defined as ‘‘the 

concentration level at or below which 

no adverse health effects are anticipated 

Federal Register / Vol. 86, No. 10 / Friday, January 15, 2021 / Proposed Rules 3915 

13CalEPA issues acute RELs as part of its Air 

Toxics Hot Spots Program, and the 1-hour and 8- 

hour values are documented in Air Toxics Hot 

Spots Program Risk Assessment Guidelines, Part I, 

The Determination of Acute Reference Exposure 

Levels for Airborne Toxicants, which is available at 

https://oehha.ca.gov/air/general-info/oehha-acute8-hour-and-chronic-reference-exposure-level-relsummary. 

14National Academy of Sciences, 2001. Standing 

Operating Procedures for Developing Acute 

Exposure Levels for Hazardous Chemicals, page 2. 

Available at https://www.epa.gov/sites/production/ 

files/2015-09/documents/sop_final_standing_

operating_procedures_2001.pdf. Note that the 

National Advisory Committee for Acute Exposure 

Guideline Levels for Hazardous Substances ended 

in October 2011, but the AEGL program continues 

to operate at the EPA and works with the National 

Academies to publish final AEGLs (https://

www.epa.gov/aegl). 

15ERPGS Procedures and Responsibilities. March 

2014. American Industrial Hygiene Association. 

Available at: https://www.aiha.org/get-involved/ 

AIHAGuidelineFoundation/EmergencyResponse

PlanningGuidelines/Documents/ERPG%20

Committee%20Standard%20Operating%20

Procedures%20%20-%20March%202014%20

Revision%20%28Updated%2010-2-2014%29.pdf. 

for a specified exposure duration.’’ 13

Acute RELs are based on the most 

sensitive, relevant, adverse health effect 

reported in the peer-reviewed medical 

and toxicological literature. They are 

designed to protect the most sensitive 

individuals in the population through 

the inclusion of margins of safety. 

Because margins of safety are 

incorporated to address data gaps and 

uncertainties, exceeding the REL does 

not automatically indicate an adverse 

health impact. AEGLs represent 

threshold exposure limits for the general 

public and are applicable to emergency 

exposures ranging from 10 minutes to 8 

hours.14 They are guideline levels for 

‘‘once-in-a-lifetime, short-term 

exposures to airborne concentrations of 

acutely toxic, high-priority chemicals.’’ 

Id. at 21. The AEGL–1 is specifically 

defined as ‘‘the airborne concentration 

(expressed as ppm (parts per million) or 

mg/m3 (milligrams per cubic meter)) of 

a substance above which it is predicted 

that the general population, including 

susceptible individuals, could 

experience notable discomfort, 

irritation, or certain asymptomatic 

nonsensory effects. However, the effects 

are not disabling and are transient and 

reversible upon cessation of exposure.’’ 

The document also notes that ‘‘Airborne 

concentrations below AEGL–1 represent 

exposure levels that can produce mild 

and progressively increasing but 

transient and nondisabling odor, taste, 

and sensory irritation or certain 

asymptomatic, nonsensory effects.’’ Id. 

AEGL–2 are defined as ‘‘the airborne 

concentration (expressed as parts per 

million or milligrams per cubic meter) 

of a substance above which it is 

predicted that the general population, 

including susceptible individuals, could 

experience irreversible or other serious, 

long-lasting adverse health effects or an 

impaired ability to escape.’’ Id. 

ERPGs are ‘‘developed for emergency 

planning and are intended as healthbased guideline concentrations for 

single exposures to chemicals.’’ 15 Id. at 

1. The ERPG–1 is defined as ‘‘the 

maximum airborne concentration below 

which it is believed that nearly all 

individuals could be exposed for up to 

1 hour without experiencing other than 

mild transient adverse health effects or 

without perceiving a clearly defined, 

objectionable odor.’’ Id. at 2. Similarly, 

the ERPG–2 is defined as ‘‘the 

maximum airborne concentration below 

which it is believed that nearly all 

individuals could be exposed for up to 

one hour without experiencing or 

developing irreversible or other serious 

health effects or symptoms which could 

impair an individual’s ability to take 

protective action.’’ Id. at 1. 

An acute REL for 1-hour exposure 

durations is typically lower than its 

corresponding AEGL–1 and ERPG–1. 

Even though their definitions are 

slightly different, AEGL–1s are often the 

same as the corresponding ERPG–1s, 

and AEGL–2s are often equal to ERPG– 

2s. The maximum HQs from our acute 

inhalation screening risk assessment 

typically result when we use the acute 

REL for a HAP. In cases where the 

maximum acute HQ exceeds 1, we also 

report the HQ based on the next highest 

acute dose-response value (usually the 

AEGL–1 and/or the ERPG–1). 

For this source category, we used 

acute factors between 2 and 10, 

depending on the type of source, to 

estimate peak hourly emissions from 

annual emissions estimates for input 

into the risk assessment modeling 

analysis. Specifically, we used a factor 

of 2 for process vents and equipment 

leaks, a factor of 4 for storage vessels, 

and a factor of 10 for transfer racks. A 

further discussion of why these factors 

were chosen can be found in the 

memorandum, Technical Support 

Document for the Cyanide Chemicals 

Manufacturing NESHAP Residual Risk 

and Technology Review Proposal, 

available in the docket for this 

rulemaking. 

In our acute inhalation screening risk 

assessment, acute impacts are deemed 

negligible for HAP for which acute HQs 

are less than or equal to 1, and no 

further analysis is performed for these 

HAP. In cases where an acute HQ from 

the screening step is greater than 1, we 

assess the site-specific data to ensure 

that the acute HQ is at an off-site 

location. For this source category, no 

data were conducted. 

4. How do we conduct the 

multipathway exposure and risk 

screening assessment? 

The EPA conducts a tiered screening 

assessment examining the potential for 

significant human health risks due to 

exposures via routes other than 

inhalation (i.e., ingestion). We first 

determine whether any sources in the 

source category emit any HAP known to 

be persistent and bioaccumulative in the 

environment, as identified in the EPA’s 

Air Toxics Risk Assessment Library (see 

Volume 1, Appendix D, at https://

www.epa.gov/fera/risk-assessment-andmodeling-air-toxics-risk-assessmentreference-library). 

For the Cyanide Chemicals 

Manufacturing source category, we 

identified potential PB–HAP emissions 

of arsenic, cadmium, lead, mercury, and 

polycyclic organic matter (POM) based 

on entries in the NEI. We note that for 

the Cyanide Chemicals Manufacturing 

source category, we modeled these 

pollutants to provide a conservative 

assessment of risks because these 

pollutants are included in the NEI. 

However, we do not believe these HAP 

are emitted from the cyanide chemicals 

manufacturing process. Very small 

amounts of these HAP are included in 

the NEI as byproducts of fuel 

combustion and are unrelated to 

cyanide chemicals manufacturing. 

After identifying potential PB–HAP 

emissions, the next step of the 

evaluation is a tiered screening 

assessment. Except for lead, the human 

health risk screening assessment for PB– 

HAP consists of three progressive tiers. 

In a Tier 1 screening assessment, we 

determine whether the magnitude of the 

facility-specific emissions of PB–HAP 

warrants further evaluation to 

characterize human health risk through 

ingestion exposure. To facilitate this 

step, we evaluate emissions against 

previously developed screening 

threshold emission rates for several PB– 

HAP that are based on a hypothetical 

upper-end screening exposure scenario 

developed for use in conjunction with 

the EPA’s Total Risk Integrated 

Methodology.Fate, Transport, and 

Ecological Exposure (TRIM.FaTE) 

model. The PB–HAP with screening 

threshold emission rates are arsenic 

compounds, cadmium compounds, 

chlorinated dibenzodioxins and furans, 

mercury compounds, and POM. Based 

on the EPA estimates of toxicity and 

bioaccumulation potential, these 

pollutants represent a conservative list 

for inclusion in multipathway risk 

assessments for RTR rules. (See Volume 

3916 Federal Register / Vol. 86, No. 10 / Friday, January 15, 2021 / Proposed Rules 

16Burger, J. 2002. Daily consumption of wild fish 

and game: Exposures of high end recreationists. 

International Journal of Environmental Health 

Research, 12:343–354. 

17U.S. EPA. Exposure Factors Handbook 2011 

Edition (Final). U.S. Environmental Protection 

Agency, Washington, DC, EPA/600/R–09/052F, 

2011. 

18 In doing so, the EPA notes that the legal 

standard for a primary NAAQS—that a standard is 

requisite to protect public health and provide an 

adequate margin of safety (CAA section 109(b))— 

differs from the CAA section 112(f) standard 

(requiring, among other things, that the standard 

provide an ‘‘ample margin of safety to protect 

public health’’). However, the primary lead NAAQS 

is a reasonable measure of determining risk 

acceptability (i.e., the first step of the Benzene 

NESHAP analysis) since it is designed to protect the 

most susceptible group in the human population— 

children, including children living near major lead 

emitting sources. 73 FR 67002/3; 73 FR 67000/3; 73 

FR 67005/1. In addition, applying the level of the 

primary lead NAAQS at the risk acceptability step 

is conservative, since that primary lead NAAQS 

reflects an adequate margin of safety. 

1, Appendix D at https://www.epa.gov/ 

sites/production/files/2013-08/ 

documents/volume_1_reflibrary.pdf.) In 

this assessment, we compare the 

facility-specific emission rates of these 

PB–HAP to the screening threshold 

emission rates for each PB–HAP to 

assess the potential for significant 

human health risks via the ingestion 

pathway. We call this application of the 

TRIM.FaTE model the Tier 1 screening 

assessment. The ratio of a facility’s 

actual emission rate to the Tier 1 

screening threshold emission rate is a 

‘‘screening value (SV).’’ 

We derive the Tier 1 screening 

threshold emission rates for these PB– 

HAP (other than lead compounds) to 

correspond to a maximum excess 

lifetime cancer risk of 1-in-1 million 

(i.e., for arsenic compounds, 

polychlorinated dibenzodioxins and 

furans, and POM) or, for HAP that cause 

noncancer health effects (i.e., cadmium 

compounds and mercury compounds), a 

maximum HQ of 1. If the emission rate 

of any one PB–HAP or combination of 

carcinogenic PB–HAP in the Tier 1 

screening assessment exceeds the Tier 1 

screening threshold emission rate for 

any facility (i.e., the SV is greater than 

1), we conduct a second screening 

assessment, which we call the Tier 2 

screening assessment. The Tier 2 

screening assessment separates the Tier 

1 combined fisher and farmer exposure 

scenario into fisher, farmer, and 

gardener scenarios that retain upperbound ingestion rates. 

In the Tier 2 screening assessment, 

the location of each facility that exceeds 

a Tier 1 screening threshold emission 

rate is used to refine the assumptions 

associated with the Tier 1 fisher and 

farmer exposure scenarios at that 

facility. A key assumption in the Tier 1 

screening assessment is that a lake 

and/or farm is located near the facility. 

As part of the Tier 2 screening 

assessment, we use a U.S. Geological 

Survey (USGS) database to identify 

actual waterbodies within 50 km of each 

facility and assume the fisher only 

consumes fish from lakes within that 50 

km zone. We also examine the 

differences between local meteorology 

near the facility and the meteorology 

used in the Tier 1 screening assessment. 

We then adjust the previouslydeveloped Tier 1 screening threshold 

emission rates for each PB–HAP for 

each facility based on an understanding 

of how exposure concentrations 

estimated for the screening scenario 

change with the use of local 

meteorology and the USGS lakes 

database. 

In the Tier 2 farmer scenario, we 

maintain an assumption that the farm is 

located within 0.5 km of the facility and 

that the farmer consumes meat, eggs, 

dairy, vegetables, and fruit produced 

near the facility. We may further refine 

the Tier 2 screening analysis by 

assessing a gardener scenario to 

characterize a range of exposures, with 

the gardener scenario being more 

plausible in RTR evaluations. Under the 

gardener scenario, we assume the 

gardener consumes home-produced 

eggs, vegetables, and fruit products at 

the same ingestion rate as the farmer. 

The Tier 2 screen continues to rely on 

the high-end food intake assumptions 

that were applied in Tier 1 for local fish 

(adult female angler at 99th percentile 

fish consumption 16) and locally grown 

or raised foods (90th percentile 

consumption of locally grown or raised 

foods for the farmer and gardener 

scenarios 17). If PB–HAP emission rates 

do not result in a Tier 2 SV greater than 

1, we consider those PB–HAP emissions 

to pose risks below a level of concern. 

If the PB–HAP emission rates for a 

facility exceed the Tier 2 screening 

threshold emission rates, we may 

conduct a Tier 3 screening assessment. 

There are several analyses that can be 

included in a Tier 3 screening 

assessment, depending upon the extent 

of refinement warranted, including 

validating that the lakes are fishable, 

locating residential/garden locations for 

urban and/or rural settings, considering 

plume-rise to estimate emissions lost 

above the mixing layer, and considering 

hourly effects of meteorology and 

plume-rise on chemical fate and 

transport (a time-series analysis). If 

necessary, the EPA may further refine 

the screening assessment through a sitespecific assessment. 

In evaluating the potential 

multipathway risk from emissions of 

lead compounds, rather than developing 

a screening threshold emission rate, we 

compare maximum estimated chronic 

inhalation exposure concentrations to 

the level of the current National 

Ambient Air Quality Standard (NAAQS) 

for lead.18 Values below the level of the 

primary (health-based) lead NAAQS are 

considered to have a low potential for 

multipathway risk. 

For further information on the 

multipathway assessment approach, see 

the Residual Risk Assessment for the 

Cyanide Chemicals Manufacturing 

Source Category in Support of the Risk 

and Technology Review 2020 Proposed 

Rule, which is available in the docket 

for this action. 

5. How do we conduct the 

environmental risk screening 

assessment? 

a. Adverse Environmental Effect, 

Environmental HAP, and Ecological 

Benchmarks 

The EPA conducts a screening 

assessment to examine the potential for 

an adverse environmental effect as 

required under section 112(f)(2)(A) of 

the CAA. Section 112(a)(7) of the CAA 

defines ‘‘adverse environmental effect’’ 

as ‘‘any significant and widespread 

adverse effect, which may reasonably be 

anticipated, to wildlife, aquatic life, or 

other natural resources, including 

adverse impacts on populations of 

endangered or threatened species or 

significant degradation of 

environmental quality over broad 

areas.’’ 

The EPA focuses on eight HAP, which 

are referred to as ‘‘environmental HAP,’’ 

in its screening assessment: six PB–HAP 

and two acid gases. The PB–HAP 

included in the screening assessment 

are arsenic compounds, cadmium 

compounds, dioxins/furans, POM, 

mercury (both inorganic mercury and 

methyl mercury), and lead compounds. 

The acid gases included in the screening 

assessment are hydrochloric acid (HCl) 

and hydrogen fluoride (HF). 

HAP that persist and bioaccumulate 

are of particular environmental concern 

because they accumulate in the soil, 

sediment, and water. The acid gases, 

HCl and HF, are included due to their 

well-documented potential to cause 

direct damage to terrestrial plants. In the 

environmental risk screening 

assessment, we evaluate the following 

four exposure media: terrestrial soils, 

surface water bodies (includes watercolumn and benthic sediments), fish 

consumed by wildlife, and air. Within 

these four exposure media, we evaluate 

nine ecological assessment endpoints, 

which are defined by the ecological 

Federal Register / Vol. 86, No. 10 / Friday, January 15, 2021 / Proposed Rules 3917 

entity and its attributes. For PB–HAP 

(other than lead), both community-level 

and population-level endpoints are 

included. For acid gases, the ecological 

assessment evaluated is terrestrial plant 

communities. 

An ecological benchmark represents a 

concentration of HAP that has been 

linked to a particular environmental 

effect level. For each environmental 

HAP, we identified the available 

ecological benchmarks for each 

assessment endpoint. We identified, 

where possible, ecological benchmarks 

at the following effect levels: probable 

effect levels, lowest-observed-adverseeffect level, and no-observed-adverseeffect level. In cases where multiple 

effect levels were available for a 

particular PB–HAP and assessment 

endpoint, we use all of the available 

effect levels to help us to determine 

whether ecological risks exist and, if so, 

whether the risks could be considered 

significant and widespread. 

For further information on how the 

environmental risk screening 

assessment was conducted, including a 

discussion of the risk metrics used, how 

the environmental HAP were identified, 

and how the ecological benchmarks 

were selected, see Appendix 9 of the 

Residual Risk Assessment for the 

Cyanide Chemicals Manufacturing 

Source Category in Support of the Risk 

and Technology Review 2020 Proposed 

Rule, which is available in the docket 

for this action. 

b. Environmental Risk Screening 

Methodology 

For the environmental risk screening 

assessment, the EPA first determined 

whether any facilities in the Cyanide 

Chemicals Manufacturing source 

category emitted any of the 

environmental HAP. For the Cyanide 

Chemicals Manufacturing source 

category, we identified potential 

emissions of arsenic, cadmium, lead, 

mercury, POM, and one acid gas, HCl, 

based on entries in the NEI. Because one 

or more of the environmental HAP 

evaluated may be emitted by at least one 

facility in the source category, we 

proceeded to the second step of the 

evaluation. As noted above, we modeled 

these emissions to err on the side of an 

overly conservative analysis because 

they are included in the NEI; however, 

we do not believe these HAP are emitted 

from the Cyanide Chemicals 

Manufacturing source category. The NEI 

entries for these HAP from these sources 

are likely the result of emissions factors 

that are used for fuel combustion and 

are unrelated to cyanide chemicals 

manufacturing. 

c. PB–HAP Methodology 

The environmental screening 

assessment includes six PB–HAP, 

arsenic compounds, cadmium 

compounds, dioxins/furans, POM, 

mercury (both inorganic mercury and 

methyl mercury), and lead compounds. 

With the exception of lead, the 

environmental risk screening 

assessment for PB–HAP consists of three 

tiers. The first tier of the environmental 

risk screening assessment uses the same 

health-protective conceptual model that 

is used for the Tier 1 human health 

screening assessment. TRIM.FaTE 

model simulations were used to backcalculate Tier 1 screening threshold 

emission rates. The screening threshold 

emission rates represent the emission 

rate in tons of pollutant per year that 

results in media concentrations at the 

facility that equal the relevant ecological 

benchmark. To assess emissions from 

each facility in the category, the 

reported emission rate for each PB–HAP 

was compared to the Tier 1 screening 

threshold emission rate for that PB–HAP 

for each assessment endpoint and effect 

level. If emissions from a facility do not 

exceed the Tier 1 screening threshold 

emission rate, the facility ‘‘passes’’ the 

screening assessment, and, therefore, is 

not evaluated further under the 

screening approach. If emissions from a 

facility exceed the Tier 1 screening 

threshold emission rate, we evaluate the 

facility further in Tier 2. 

In Tier 2 of the environmental 

screening assessment, the screening 

threshold emission rates are adjusted to 

account for local meteorology and the 

actual location of lakes in the vicinity of 

facilities that did not pass the Tier 1 

screening assessment. For soils, we 

evaluate the average soil concentration 

for all soil parcels within a 7.5-km 

radius for each facility and PB–HAP. 

For the water, sediment, and fish tissue 

concentrations, the highest value for 

each facility for each pollutant is used. 

If emission concentrations from a 

facility do not exceed the Tier 2 

screening threshold emission rate, the 

facility ‘‘passes’’ the screening 

assessment and typically is not 

evaluated further. If emissions from a 

facility exceed the Tier 2 screening 

threshold emission rate, we evaluate the 

facility further in Tier 3. 

As in the multipathway human health 

risk assessment, in Tier 3 of the 

environmental screening assessment, we 

examine the suitability of the lakes 

around the facilities to support life and 

remove those that are not suitable (e.g., 

lakes that have been filled in or are 

industrial ponds), adjust emissions for 

plume-rise, and conduct hour-by-hour 

time-series assessments. If these Tier 3 

adjustments to the screening threshold 

emission rates still indicate the 

potential for an adverse environmental 

effect (i.e., facility emission rate exceeds 

the screening threshold emission rate), 

we may elect to conduct a more refined 

assessment using more site-specific 

information. If, after additional 

refinement, the facility emission rate 

still exceeds the screening threshold 

emission rate, the facility may have the 

potential to cause an adverse 

environmental effect. 

To evaluate the potential for an 

adverse environmental effect from lead, 

we compared the average modeled air 

concentrations (from HEM–3) of lead 

around each facility in the source 

category to the level of the secondary 

NAAQS for lead. The secondary lead 

NAAQS is a reasonable means of 

evaluating environmental risk because it 

is set to provide substantial protection 

against adverse welfare effects which 

can include ‘‘effects on soils, water, 

crops, vegetation, man-made materials, 

animals, wildlife, weather, visibility and 

climate, damage to and deterioration of 

property, and hazards to transportation, 

as well as effects on economic values 

and on personal comfort and wellbeing.’’ 

d. Acid Gas Environmental Risk 

Methodology 

The environmental screening 

assessment for acid gases evaluates the 

potential phytotoxicity and reduced 

productivity of plants due to chronic 

exposure to HF and HCl. The 

environmental risk screening 

methodology for acid gases is a singletier screening assessment that compares 

modeled ambient air concentrations 

(from AERMOD) to the ecological 

benchmarks for each acid gas. To 

identify a potential adverse 

environmental effect (as defined in 

section 112(a)(7) of the CAA) from 

emissions of HF and HCl, we evaluate 

the following metrics: the size of the 

modeled area around each facility that 

exceeds the ecological benchmark for 

each acid gas, in acres and square 

kilometers; the percentage of the 

modeled area around each facility that 

exceeds the ecological benchmark for 

each acid gas; and the area-weighted 

average SV around each facility 

(calculated by dividing the areaweighted average concentration over the 

50-km modeling domain by the 

ecological benchmark for each acid gas). 

For further information on the 

environmental screening assessment 

approach, see Appendix 9 of the 

Residual Risk Assessment for the 

Cyanide Chemicals Manufacturing 

3918 Federal Register / Vol. 86, No. 10 / Friday, January 15, 2021 / Proposed Rules 

Source Category in Support of the Risk 

and Technology Review 2020 Proposed 

Rule, which is available in the docket 

for this action. 

6. How do we conduct facility-wide 

assessments? 

To put the source category risks in 

context, we typically examine the risks 

from the entire ‘‘facility,’’ where the 

facility includes all HAP-emitting 

operations within a contiguous area and 

under common control. In other words, 

we examine the HAP emissions not only 

from the source category emission 

points of interest, but also emissions of 

HAP from all other emission sources at 

the facility for which we have data. For 

this source category, we conducted the 

facility-wide assessment using a dataset 

compiled from the 2017 NEI. The source 

category records of that NEI dataset 

were removed, evaluated, and updated 

as described in section II.C of this 

preamble: What data collection 

activities were conducted to support 

this action? Once a quality assured 

source category dataset was available, it 

was placed back with the remaining 

records from the NEI for that facility. 

The facility-wide file was then used to 

analyze risks due to the inhalation of 

HAP that are emitted ‘‘facility-wide’’ for 

the populations residing within 50 km 

of each facility, consistent with the 

methods used for the source category 

analysis described above. For these 

facility-wide risk analyses, the modeled 

source category risks were compared to 

the facility-wide risks to determine the 

portion of the facility-wide risks that 

could be attributed to the source 

category addressed in this proposal. We 

also specifically examined the facility 

that was associated with the highest 

estimate of risk and determined the 

percentage of that risk attributable to the 

source category of interest. The Residual 

Risk Assessment for the Cyanide 

Chemicals Manufacturing Source 

Category in Support of the Risk and 

Technology Review 2020 Proposed Rule, 

available through the docket for this 

action, provides the methodology and 

results of the facility-wide analyses, 

including all facility-wide risks and the 

percentage of source category 

contribution to facility-wide risks. 

For this source category, we 

conducted the facility-wide assessment 

using a dataset that the EPA compiled 

from the 2017 NEI. We used the NEI 

data for the facility and did not adjust 

any category or ‘‘non-category’’ data. 

Therefore, there could be differences in 

the dataset from that used for the source 

category assessments described in this 

preamble. We analyzed risks due to the 

inhalation of HAP that are emitted 

‘‘facility-wide’’ for the populations 

residing within 50 km of each facility, 

consistent with the methods used for 

the source category analysis described 

above. For these facility-wide risk 

analyses, we made a reasonable attempt 

to identify the source category risks, and 

these risks were compared to the 

facility-wide risks to determine the 

portion of facility-wide risks that could 

be attributed to the source category 

addressed in this proposal. We also 

specifically examined the facility that 

was associated with the highest estimate 

of risk and determined the percentage of 

that risk attributable to the source 

category of interest. The Residual Risk 

Assessment for the Cyanide Chemicals 

Manufacturing Source Category in 

Support of the Risk and Technology 

Review 2020 Proposed Rule, available 

through the docket for this action, 

provides the methodology and results of 

the facility-wide analyses, including all 

facility-wide risks and the percentage of 

source category contribution to facilitywide risks. 

7. How do we consider uncertainties in 

risk assessment? 

Uncertainty and the potential for bias 

are inherent in all risk assessments, 

including those performed for this 

proposal. Although uncertainty exists, 

we believe that our approach, which 

used conservative tools and 

assumptions, ensures that our decisions 

are health and environmentally 

protective. A brief discussion of the 

uncertainties in the RTR emissions 

dataset, dispersion modeling, inhalation 

exposure estimates, and dose-response 

relationships follows below. Also 

included are those uncertainties specific 

to our acute screening assessments, 

multipathway screening assessments, 

and our environmental risk screening 

assessments. A more thorough 

discussion of these uncertainties is 

included in the Residual Risk 

Assessment for the Cyanide Chemicals 

Manufacturing Source Category in 

Support of the Risk and Technology 

Review 2020 Proposed Rule, which is 

available in the docket for this action. If 

a multipathway site-specific assessment 

was performed for this source category, 

a full discussion of the uncertainties 

associated with that assessment can be 

found in Appendix 11 of that document, 

Site-Specific Human Health 

Multipathway Residual Risk Assessment 

Report. 

a. Uncertainties in the RTR Emissions 

Dataset 

Although the development of the RTR 

emissions dataset involved quality 

assurance/quality control processes, the 

accuracy of emissions values will vary 

depending on the source of the data, the 

degree to which data are incomplete or 

missing, the degree to which 

assumptions made to complete the 

datasets are accurate, errors in emission 

estimates, and other factors. The 

emission estimates considered in this 

analysis generally are annual totals for 

certain years, and they do not reflect 

short-term fluctuations during the 

course of a year or variations from year 

to year. The estimates of peak hourly 

emission rates for the acute effects 

screening assessment were based on an 

emission adjustment factor applied to 

the average annual hourly emission 

rates, which are intended to account for 

emission fluctuations due to normal 

facility operations. 

b. Uncertainties in Dispersion Modeling 

We recognize there is uncertainty in 

ambient concentration estimates 

associated with any model, including 

the EPA’s recommended regulatory 

dispersion model, AERMOD. In using a 

model to estimate ambient pollutant 

concentrations, the user chooses certain 

options to apply. For RTR assessments, 

we select some model options that have 

the potential to overestimate ambient air 

concentrations (e.g., not including 

plume depletion or pollutant 

transformation). We select other model 

options that have the potential to 

underestimate ambient impacts (e.g., not 

including building downwash). Other 

options that we select have the potential 

to either under- or overestimate ambient 

levels (e.g., meteorology and receptor 

locations). On balance, considering the 

directional nature of the uncertainties 

commonly present in ambient 

concentrations estimated by dispersion 

models, the approach we apply in the 

RTR assessments should yield unbiased 

estimates of ambient HAP 

concentrations. We also note that the 

selection of meteorology dataset 

location could have an impact on the 

risk estimates. As we continue to update 

and expand our library of 

meteorological station data used in our 

risk assessments, we expect to reduce 

this variability. 

c. Uncertainties in Inhalation Exposure 

Assessment 

Although every effort is made to 

identify all of the relevant facilities and 

emission points, as well as to develop 

accurate estimates of the annual 

emission rates for all relevant HAP, the 

uncertainties in our emission inventory 

likely dominate the uncertainties in the 

exposure assessment. Some 

uncertainties in our exposure 

assessment include human mobility, 

Federal Register / Vol. 86, No. 10 / Friday, January 15, 2021 / Proposed Rules 3919 

19 IRIS glossary (https://ofmpub.epa.gov/ 

sor_internet/registry/termreg/searchandretrieve/ 

glossariesandkeywordlists/search.do?details=

&glossaryName=IRIS%20Glossary). 

20An exception to this is the URE for benzene, 

which is considered to cover a range of values, each 

end of which is considered to be equally plausible, 

and which is based on maximum likelihood 

estimates. 

21See A Review of the Reference Dose and 

Reference Concentration Processes, U.S. EPA, 

December 2002, and Methods for Derivation of 

Inhalation Reference Concentrations and 

Application of Inhalation Dosimetry, U.S. EPA, 

1994. 

using the centroid of each census block, 

assuming lifetime exposure, and 

assuming only outdoor exposures. For 

most of these factors, there is neither an 

under nor overestimate when looking at 

the maximum individual risk or the 

incidence, but the shape of the 

distribution of risks may be affected. 

With respect to outdoor exposures, 

actual exposures may not be as high if 

people spend time indoors, especially 

for very reactive pollutants or larger 

particles. For all factors, we reduce 

uncertainty when possible. For 

example, with respect to census-block 

centroids, we analyze large blocks using 

aerial imagery and adjust locations of 

the block centroids to better represent 

the population in the blocks. We also 

add additional receptor locations where 

the population of a block is not well 

represented by a single location. 

d. Uncertainties in Dose-Response 

Relationships 

There are uncertainties inherent in 

the development of the dose-response 

values used in our risk assessments for 

cancer effects from chronic exposures 

and noncancer effects from both chronic 

and acute exposures. Some 

uncertainties are generally expressed 

quantitatively, and others are generally 

expressed in qualitative terms. We note, 

as a preface to this discussion, a point 

on dose-response uncertainty that is 

stated in the EPA’s 2005 Guidelines for 

Carcinogen Risk Assessment; namely, 

that ‘‘the primary goal of EPA actions is 

protection of human health; 

accordingly, as an Agency policy, risk 

assessment procedures, including 

default options that are used in the 

absence of scientific data to the 

contrary, should be health protective’’ 

(the EPA’s 2005 Guidelines for 

Carcinogen Risk Assessment, pages 1 

through 7). This is the approach 

followed here as summarized in the 

next paragraphs. 

Cancer UREs used in our risk 

assessments are those that have been 

developed to generally provide an upper 

bound estimate of risk.19 That is, they 

represent a ‘‘plausible upper limit to the 

true value of a quantity’’ (although this 

is usually not a true statistical 

confidence limit). In some 

circumstances, the true risk could be as 

low as zero; however, in other 

circumstances the risk could be 

greater.20 Chronic noncancer RfC and 

reference dose (RfD) values represent 

chronic exposure levels that are 

intended to be health-protective levels. 

To derive dose-response values that are 

intended to be ‘‘without appreciable 

risk,’’ the methodology relies upon an 

uncertainty factor (UF) approach,21

which considers uncertainty, variability, 

and gaps in the available data. The UFs 

are applied to derive dose-response 

values that are intended to protect 

against appreciable risk of deleterious 

effects. 

Many of the UFs used to account for 

variability and uncertainty in the 

development of acute dose-response 

values are quite similar to those 

developed for chronic durations. 

Additional adjustments are often 

applied to account for uncertainty in 

extrapolation from observations at one 

exposure duration (e.g., 4 hours) to 

derive an acute dose-response value at 

another exposure duration (e.g., 1 hour). 

Not all acute dose-response values are 

developed for the same purpose, and 

care must be taken when interpreting 

the results of an acute assessment of 

human health effects relative to the 

dose-response value or values being 

exceeded. Where relevant to the 

estimated exposures, the lack of acute 

dose-response values at different levels 

of severity should be factored into the 

risk characterization as potential 

uncertainties. 

Uncertainty also exists in the 

selection of ecological benchmarks for 

the environmental risk screening 

assessment. We established a hierarchy 

of preferred benchmark sources to allow 

selection of benchmarks for each 

environmental HAP at each ecological 

assessment endpoint. We searched for 

benchmarks for three effect levels (i.e., 

no-effects level, threshold-effect level, 

and probable effect level), but not all 

combinations of ecological assessment/ 

environmental HAP had benchmarks for 

all three effect levels. Where multiple 

effect levels were available for a 

particular HAP and assessment 

endpoint, we used all of the available 

effect levels to help us determine 

whether risk exists and whether the risk 

could be considered significant and 

widespread. 

For a group of compounds that are 

unspeciated (e.g., glycol ethers), we 

conservatively use the most protective 

dose-response value of an individual 

compound in that group to estimate 

risk. Similarly, for an individual 

compound in a group (e.g., ethylene 

glycol diethyl ether) that does not have 

a specified dose-response value, we also 

apply the most protective dose-response 

value from the other compounds in the 

group to estimate risk. 

e. Uncertainties in Acute Inhalation 

Screening Assessments 

In addition to the uncertainties 

highlighted above, there are several 

factors specific to the acute exposure 

assessment that the EPA conducts as 

part of the risk review under section 112 

of the CAA. The accuracy of an acute 

inhalation exposure assessment 

depends on the simultaneous 

occurrence of independent factors that 

may vary greatly, such as hourly 

emissions rates, meteorology, and the 

presence of a person. In the acute 

screening assessment that we conduct 

under the RTR program, we assume that 

peak emissions from the source category 

and reasonable worst-case air dispersion 

conditions (i.e., 99th percentile) cooccur. We then include the additional 

assumption that a person is located at 

this point at the same time. Together, 

these assumptions represent a 

reasonable worst-case actual exposure 

scenario. In most cases, it is unlikely 

that a person would be located at the 

point of maximum exposure during the 

time when peak emissions and 

reasonable worst-case air dispersion 

conditions occur simultaneously. 

f. Uncertainties in the Multipathway 

and Environmental Risk Screening 

Assessments 

For each source category, we 

generally rely on site-specific levels of 

PB–HAP or environmental HAP 

emissions to determine whether a 

refined assessment of the impacts from 

multipathway exposures is necessary or 

whether it is necessary to perform an 

environmental screening assessment. 

This determination is based on the 

results of a three-tiered screening 

assessment that relies on the outputs 

from models—TRIM.FaTE and 

AERMOD—that estimate environmental 

pollutant concentrations and human 

exposures for five PB–HAP (dioxins, 

POM, mercury, cadmium, and arsenic) 

and two acid gases (HF and HCl). For 

lead, we use AERMOD to determine 

ambient air concentrations, which are 

then compared to the secondary 

NAAQS standard for lead. Two 

important types of uncertainty 

associated with the use of these models 

in RTR risk assessments and inherent to 

any assessment that relies on 

3920 Federal Register / Vol. 86, No. 10 / Friday, January 15, 2021 / Proposed Rules 

22 In the context of this discussion, the term 

‘‘uncertainty’’ as it pertains to exposure and risk 

encompasses both variability in the range of 

expected inputs and screening results due to 

existing spatial, temporal, and other factors, as well 

as uncertainty in being able to accurately estimate 

the true result. 

23The EPA not only has authority under CAA 

section 112(d)(2) and (3) to set MACT standards for 

previously unregulated HAP emissions at any time, 

but is required to address any previously 

unregulated HAP emissions as part of its periodic 

review of MACT standards under CAA section 

112(d)(6). LEAN v. EPA, 955 F3d at 1091–1099. 

environmental modeling are model 

uncertainty and input uncertainty.22

Model uncertainty concerns whether 

the model adequately represents the 

actual processes (e.g., movement and 

accumulation) that might occur in the 

environment. For example, does the 

model adequately describe the 

movement of a pollutant through the 

soil? This type of uncertainty is difficult 

to quantify. However, based on feedback 

received from previous EPA SAB 

reviews and other reviews, we are 

confident that the models used in the 

screening assessments are appropriate 

and state-of-the-art for the multipathway 

and environmental screening risk 

assessments conducted in support of 

RTRs. 

Input uncertainty is concerned with 

how accurately the models have been 

configured and parameterized for the 

assessment at hand. For Tier 1 of the 

multipathway and environmental 

screening assessments, we configured 

the models to avoid underestimating 

exposure and risk. This was 

accomplished by selecting upper-end 

values from nationally representative 

datasets for the more influential 

parameters in the environmental model, 

including selection and spatial 

configuration of the area of interest, lake 

location and size, meteorology, surface 

water, soil characteristics, and structure 

of the aquatic food web. We also assume 

an ingestion exposure scenario and 

values for human exposure factors that 

represent reasonable maximum 

exposures. 

In Tier 2 of the multipathway and 

environmental screening assessments, 

we refine the model inputs to account 

for meteorological patterns in the 

vicinity of the facility versus using 

upper-end national values, and we 

identify the actual location of lakes near 

the facility rather than the default lake 

location that we apply in Tier 1. By 

refining the screening approach in Tier 

2 to account for local geographical and 

meteorological data, we decrease the 

likelihood that concentrations in 

environmental media are overestimated, 

thereby increasing the usefulness of the 

screening assessment. In Tier 3 of the 

screening assessments, we refine the 

model inputs again to account for hourby-hour plume-rise and the height of the 

mixing layer. We can also use those 

hour-by-hour meteorological data in a 

TRIM.FaTE run using the screening 

configuration corresponding to the lake 

location. These refinements produce a 

more accurate estimate of chemical 

concentrations in the media of interest, 

thereby reducing the uncertainty with 

those estimates. The assumptions and 

the associated uncertainties regarding 

the selected ingestion exposure scenario 

are the same for all three tiers. 

For the environmental screening 

assessment for acid gases, we employ a 

single-tiered approach. We use the 

modeled air concentrations and 

compare those with ecological 

benchmarks. 

For all tiers of the multipathway and 

environmental screening assessments, 

our approach to addressing model input 

uncertainty is generally cautious. We 

choose model inputs from the upper 

end of the range of possible values for 

the influential parameters used in the 

models, and we assume that the 

exposed individual exhibits ingestion 

behavior that would lead to a high total 

exposure. This approach reduces the 

likelihood of not identifying high risks 

for adverse impacts. 

Despite the uncertainties, when 

individual pollutants or facilities do not 

exceed screening threshold emission 

rates (i.e., screen out), we are confident 

that the potential for adverse 

multipathway impacts on human health 

is very low. On the other hand, when 

individual pollutants or facilities do 

exceed screening threshold emission 

rates, it does not mean that impacts are 

significant, only that we cannot rule out 

that possibility and that a refined 

assessment for the site might be 

necessary to obtain a more accurate risk 

characterization for the source category. 

The EPA evaluates the following HAP 

in the multipathway and/or 

environmental risk screening 

assessments, where applicable: Arsenic, 

cadmium, dioxins/furans, lead, mercury 

(both inorganic and methyl mercury), 

POM, HCl, and HF. These HAP 

represent pollutants that can cause 

adverse impacts either through direct 

exposure to HAP in the air or through 

exposure to HAP that are deposited 

from the air onto soils and surface 

waters and then through the 

environment into the food web. These 

HAP represent those HAP for which we 

can conduct a meaningful multipathway 

or environmental screening risk 

assessment. For other HAP not included 

in our screening assessments, the model 

has not been parameterized such that it 

can be used for that purpose. In some 

cases, depending on the HAP, we may 

not have appropriate multipathway 

models that allow us to predict the 

concentration of that pollutant. The EPA 

acknowledges that other HAP beyond 

these that we are evaluating may have 

the potential to cause adverse effects 

and, therefore, the EPA may evaluate 

other relevant HAP in the future, as 

modeling science and resources allow. 

IV. Analytical Results and Proposed 

Decisions 

A. What actions are we taking pursuant 

to CAA sections 112(d)(2) and 

112(d)(3)? 

We are proposing standards pursuant 

to CAA section 112(d)(2) for process 

wastewater from existing cyanide 

chemical manufacturing process units, 

which was previously unregulated.23

During development of the initial 

MACT standards, we identified process 

wastewater at existing sources as a 

potential source of emissions of 

hydrogen cyanide, acetonitrile, and 

acrylonitrile. See 65 FR 76408, 76411, 

and 76413, December 6, 2000, for a 

discussion of the HAP emitted from 

cyanide chemicals manufacturing. At 

that time, we identified measures 

undertaken at cyanide chemicals 

manufacturing facilities to comply with 

other NESHAP as the ‘‘MACT floor,’’ 

but we did not include these measures 

in 40 CFR part 63, subpart YY for 

existing cyanide chemical 

manufacturing process units. Based on 

our review, we are proposing to find 

that these measures reflect the best 

performing sources in the source 

category. The results and proposed 

decisions based on the analyses 

performed pursuant to CAA section 

112(d)(2) and (3) are presented below. 

For this proposal, we reviewed title V 

permits for facilities subject to the 

Cyanide Chemicals Manufacturing 

NESHAP and determined that all 

cyanide chemicals manufacturing 

facilities are co-located with processes 

subject to the Hazardous Organic 

NESHAP (HON) or substantively similar 

requirements. In the 2000 NESHAP 

proposal, we stated that wastewater 

treatment units at cyanide chemicals 

manufacturing facilities are typical of 

synthetic organic chemicals 

manufacturing facilities subject to the 

HON. The wastewater requirements of 

the HON are already an approved means 

of compliance for wastewater emission 

sources subject to 40 CFR part 63, 

subpart YY as stated in 40 CFR 

63.1100(g)(5). We are proposing to 

require compliance with HON 

wastewater requirements for process 

Federal Register / Vol. 86, No. 10 / Friday, January 15, 2021 / Proposed Rules 3921 

wastewater at existing sources, which 

will ensure all affected sources at 

cyanide chemicals manufacturing 

facilities are subject to MACT standards. 

We are proposing these requirements for 

cyanide chemicals manufacturing 

existing sources because such 

requirements represent: (1) The 

measures employed by the best 

performing sources in the category; and 

(2) an already acceptable means of 

compliance for wastewater emissions at 

sources subject to subpart YY. We 

believe that these requirements will not 

require additional controls or emissions 

reductions since existing sources we 

have identified as subject to the Cyanide 

Chemicals Manufacturing NESHAP are 

already subject to the HON or 

substantively identical wastewater 

requirements in another NESHAP. 

We are also adding the HON 

requirements for waste management 

units upstream of an open or closed 

biological treatment process to the new 

source standard to ensure demonstrable 

compliance measures are in place for 

these sources; however, we believe 

these measures would already be 

employed by any new sources to 

achieve the combined 93 percent 

capture and control of HAP emissions 

from wastewater required for process 

wastewater emissions at new sources 

subject to the Cyanide Chemicals 

Manufacturing NESHAP. 

We have identified three HAP that 

may be present in process wastewater 

streams at cyanide chemicals 

manufacturing facilities: Hydrogen 

cyanide, acetonitrile, and acrylonitrile. 

We are proposing to include hydrogen 

cyanide in the calculations required to 

determine compliance with the 

wastewater standard for the Cyanide 

Chemicals Manufacturing source 

category to ensure all HAP potentially 

present in process wastewater are 

subject to MACT standards. The other 

two HAP that may be present in cyanide 

chemicals manufacturing wastewater 

(acetonitrile and acrylonitrile) are 

already included in the list of 

compounds subject to the HON 

wastewater provisions. We do not 

expect significant amounts of hydrogen 

cyanide to be present in these process 

wastewater streams. When developing 

the 2002 NESHAP, facilities that were 

surveyed reported very low levels of 

hydrogen cyanide in their wastewaters 

with one exception. The only facility 

that had high levels of hydrogen 

cyanide in its wastewater used add-on 

controls to remove the hydrogen 

cyanide prior to discharge. That facility 

was the basis for the ‘‘new source’’ 

MACT floor. We expect any facilities 

with high levels of hydrogen cyanide in 

their wastewater would already possess 

add-on controls similar to those present 

at the single existing source with high 

levels of hydrogen cyanide in order to 

meet effluent discharge limits and 

protect the biological wastewater 

treatment systems used at these 

facilities. We are including hydrogen 

cyanide in these calculations to ensure 

that all HAP emitted by the source 

category are subject to MACT standards. 

Nevertheless, we are seeking 

comment on whether facilities would 

need to install additional controls, 

achieve additional emissions 

reductions, or incur significant costs as 

a result of the proposed standards for 

process wastewater. For this proposed 

rule, we did not identify any new 

control technologies or developments in 

existing technologies to evaluate as 

‘‘beyond-the-floor’’ controls other than 

the controls evaluated during the initial 

MACT standards. We did not find any 

data to support changing the conclusion 

that application of the new source 

MACT limit for process wastewater 

emissions to existing sources is 

unreasonable (See 65 FR 76419 and 

Docket Item No. EPA–HQ–OAR–2004– 

0041–0003). 

B. What are the results of the risk 

assessment and analyses? 

1. Chronic Inhalation Risk Assessment 

Results 

The EPA estimated inhalation risk 

based on actual and allowable 

emissions, which we determined are the 

same for this category. The estimated 

baseline inhalation MIR posed by the 

source category is 5-in-1 million based 

on actual emissions and MACTallowable emissions. The total estimated 

cancer incidence based on actual or 

allowable emission levels is 0.004 

excess cancer cases per year, or one case 

every 250 years. Emissions of 

acrylonitrile from process vents account 

for 95 percent of the cancer incidence. 

Approximately 61,653 people are 

exposed to cancer risk greater than or 

equal to 1-in-1 million based upon 

actual and allowable emissions (see 

Table 1 of this preamble). 

The maximum chronic noncancer 

TOSHI values for the source category 

were estimated to be 1 for neurological 

effects based on actual and allowable 

emissions. For both actual and 

allowable emissions, risk was driven by 

hydrogen cyanide emissions from 

process vents, wastewater, and 

equipment leaks. 

TABLE 1—INHALATION RISK ASSESSMENT SUMMARY FOR CYANIDE CHEMICALS MANUFACTURING 1 SOURCE CATEGORY

(40 CFR PART 63, SUBPART YY) 

Risk assessment Number of 

facilities 2

Maximum 

individual 

cancer risk 

(1-in-1 

million) 3

Estimated 

population at 

increased risk 

of cancer ≥ 

1-in-1 

million 

Estimated 

annual cancer 

incidence 

(cases per 

year) 

Maximum chronic 

noncancer 

TOSHI 4

Maximum screening acute noncancer HQ 5

Baseline Actual Emissions 

Source Category ............................ 13 5 61,653 0.004 1 (neurological) ... 1 (REL) 

Facility-Wide .................................. 13 200 266,532 0.04 1 (neurological) ...

Baseline Allowable Emissions 

Source Category ............................ 13 5 61,653 0.004 1 (neurological) ...

1Based on actual and allowable emissions. 

2 Number of facilities evaluated in the risk assessment. Includes 13 operating facilities subject to 40 CFR part 63, subpart YY. 

3 Maximum individual excess lifetime cancer risk due to HAP emissions from the source category. 

4 Maximum TOSHI. The target organ with the highest TOSHI for the Cyanide Chemicals Manufacturing source category is the neurological 

system. 5The maximum estimated acute exposure concentration was divided by available short-term threshold values to develop an array of HQ values. The acute HQ shown was based upon the lowest acute 1-hour dose-response value, the REL for hydrogen cyanide. When an HQ exceeds 

1, we also show the HQ using the next lowest available acute dose-response value. 

3922 Federal Register / Vol. 86, No. 10 / Friday, January 15, 2021 / Proposed Rules 

2. Screening Level Acute Risk 

Assessment Results 

Based on our screening analysis of 

reasonable worst-case acute exposure to 

actual emissions from the category, no 

HAP exposures result in an HQ greater 

than 1 based upon the 1-hour REL. As 

discussed in section III.C.3.c of this 

preamble, for this source category, we 

used acute factors between 2 and 10, 

depending on the type of source. 

Specifically, we used a factor of 2 for 

process vents and equipment leaks, a 

factor of 4 for storage vessels, and a 

factor of 10 for transfer racks. A further 

discussion of why these factors were 

chosen can be found in the 

memorandum, Technical Support 

Document for the Cyanide Chemicals 

Manufacturing NESHAP Residual Risk 

and Technology Review Proposal, 

available in the docket for this 

rulemaking. 

3. Multipathway Risk Screening Results 

Three of the 13 facilities in this source 

category reported emissions of PB–HAP 

in the NEI which include POM (of 

which polycyclic aromatic 

hydrocarbons is a subset), lead 

compounds, arsenic compounds, 

cadmium compounds, and mercury 

compounds. We note that for the 

Cyanide Chemicals Manufacturing 

source category, while we modeled 

these emissions, none of these HAP are 

expected to be emitted from the source 

category and they were only modeled to 

provide a conservative estimate of risk 

because they were included in the NEI. 

To identify potential multipathway 

health risks from PB–HAP other than 

lead, we first performed a tiered 

screening assessment (Tiers 1, 2, and 3) 

based on emissions of PB–HAP emitted 

from each facility in the source category. 

Arsenic emissions from a single facility 

exceeded the Tier 1 cancer screening 

threshold emission rate with a 

maximum SV of 2. No facilities had 

POM emissions exceeding the Tier 1 

cancer screening threshold emission 

rate. Mercury emissions from a single 

facility exceeded the Tier 1 noncancer 

screening threshold emission rate with 

a maximum SV of 2. No facilities had 

cadmium emissions exceeding the Tier 

1 noncancer screening threshold 

emission rate. For the facilities and HAP 

for which the Tier 1 threshold emissions 

rates were exceeded (i.e., SV greater 

than 1), we conducted a Tier 2 screening 

analysis. In the Tier 2 screening 

analysis, no facilities had an SV greater 

than 1. Specifically, the maximum Tier 

2 cancer SV was less than 1 for both the 

farmer scenario for arsenic (0.4) and the 

fisher scenario for mercury (0.3). 

Further facility details on the 

multipathway screening analysis can be 

found in Appendix 10 of the Residual 

Risk Assessment for the Cyanide 

Chemical Manufacturing Source 

Category in Support of the Risk and 

Technology Review 2020 Proposed Rule. 

An SV in any of the tiers is not an 

estimate of the cancer risk or a 

noncancer HQ. Rather, an SV represents 

a high-end estimate of what the risk or 

HQ may be. For example, facility 

emissions resulting in an SV of 2 for a 

non-carcinogen can be interpreted to 

mean that we are confident that the HQ 

would be lower than 2. Similarly, 

facility emissions resulting in a cancer 

SV of 20 for a carcinogen means that we 

are confident that the cancer risk is 

lower than 20-in-1 million. Our 

confidence comes from the healthprotective assumptions that are 

incorporated into the screens: We 

choose inputs from the upper end of the 

range of possible values for the 

influential parameters used in the 

screens and we assume food 

consumption behaviors that would lead 

to high total exposure. This risk 

assessment estimates the maximum 

hazard for mercury and cadmium 

through fish consumption based on 

upper bound screens and the maximum 

excess cancer risks from POM and 

arsenic through ingestion of fish and 

farm produce. 

In evaluating the potential for adverse 

health effects from emissions of lead, 

the EPA compared modeled annual lead 

concentrations to the secondary NAAQS 

level for lead (0.15 mg/m3, arithmetic 

mean concentration over a 3-month 

period). The highest annual average lead 

concentration, 0.00000065 mg/m3, is 

orders of magnitude below the NAAQS 

level for lead, indicating a low potential 

for adverse health impacts. 

4. Environmental Risk Screening Results 

As described in section III.A of this 

preamble, we conducted an 

environmental risk screening 

assessment for the Cyanide Chemical 

Manufacturing source category for the 

following pollutants: arsenic, cadmium, 

HCl, lead, mercury (methyl mercury and 

mercuric chloride), and POM. As noted 

in our discussion of the multipathway 

risk assessment results, these HAP are 

not associated with cyanide chemicals 

manufacturing and are not emitted from 

the source category. There were NEI 

entries for small amounts of these 

pollutants and we chose to model these 

emissions to err on the side of an overly 

conservative assessment. 

In the Tier 1 screening analysis for the 

above PB–HAP (other than lead, which 

was evaluated differently), the 

maximum Tier 1 SV was less than or 

equal to 1 for all PB–HAP. 

For lead, we did not estimate any 

exceedances of the secondary lead 

NAAQS. For HCl, the average modeled 

concentration around each facility (i.e., 

the average concentration of all off-site 

data points in the modeling domain) did 

not exceed any ecological benchmark. In 

addition, for the one facility that 

reported HCl emissions, each individual 

modeled concentration of HCl (i.e., each 

off-site data point in the modeling 

domain) was below the ecological 

benchmarks for HCl. 

Based on the results of the 

environmental risk screening analysis, 

we do not expect an adverse 

environmental effect as a result of HAP 

emissions from this source category. 

5. Facility-Wide Risk Results 

The EPA estimated inhalation risk 

based on facility-wide emissions. The 

estimated maximum individual excess 

lifetime cancer risk based on facilitywide emissions was 200-in-1 million, 

with 0.04 excess cancer cases per year, 

or one case every 25 years. This cancer 

risk is driven by emissions sources that 

are not in the Cyanide Chemicals 

Manufacturing source category; 

specifically, emissions of ethylene oxide 

and coke oven emissions from noncategory sources account for 95 percent 

of the cancer incidence. Approximately 

150 people are exposed to an excess 

cancer risk greater than or equal to 100- 

in-1 million, with 266,532 people 

exposed to an excess cancer risk above 

1-in-1 million (see Table 1 of this 

preamble). The estimated maximum 

chronic noncancer TOSHI values for the 

facility-wide assessment was the same 

as estimated based on actual and 

allowable emissions from the source 

category—a TOSHI equal to 1 for 

neurological effects driven by hydrogen 

cyanide emissions from process vents, 

wastewater, and equipment leaks. 

Regarding the facility-wide risks due 

to ethylene oxide, which are emitted by 

sources that are not part of the Cyanide 

Chemicals Manufacturing source 

category, we intend to continue to 

evaluate those facility-wide estimated 

emissions and risks further and may 

address these in separate actions, as 

appropriate. In particular, the EPA is 

addressing ethylene oxide in response 

to the results of the latest NATA 

released in August 2018, which 

identified the chemical as a potential 

concern in several areas across the 

country (NATA is the Agency’s 

nationwide air toxics screening tool, 

designed to help the EPA and state, 

local, and tribal air agencies identify 

areas, pollutants, or types of sources for 

Federal Register / Vol. 86, No. 10 / Friday, January 15, 2021 / Proposed Rules 3923 

24 Demographic groups included in the analysis 

are: White, African American, Native American, 

other races and multiracial, Hispanic or Latino, 

children 17 years of age and under, adults 18 to 64 

years of age, adults 65 years of age and over, adults 

without a high school diploma, people living below 

the poverty level, people living two times the 

poverty level, and linguistically isolated people. 

further examination). The latest NATA 

estimates that ethylene oxide 

significantly contributes to potential 

elevated cancer risks in some census 

tracts across the U.S. (less than 1 

percent of the total number of tracts). 

These elevated risks are largely driven 

by an EPA risk value that was updated 

in late 2016. The EPA will work with 

industry and state, local, and tribal air 

agencies as the EPA takes a two-pronged 

approach to address ethylene oxide 

emissions by: (1) Reviewing and, as 

appropriate, revising CAA regulations 

for facilities that emit ethylene oxide— 

starting with air toxics emissions 

standards for miscellaneous organic 

chemical manufacturing facilities (85 FR 

49084, August 12, 2020) and 

commercial sterilizers; and (2) 

conducting site-specific risk 

assessments and, as necessary, 

implementing emission control 

strategies for targeted high-risk facilities. 

The EPA will post updates on its work 

to address ethylene oxide on its website 

at: https://www.epa.gov/ethylene-oxide. 

6. What demographic groups might 

benefit from this regulation? 

To examine the potential for any 

environmental justice issues that might 

be associated with the source category, 

we performed a demographic analysis, 

which is an assessment of risk to 

individual demographic groups of the 

populations living within 5 km and 

within 50 km of the facilities. In the 

analysis, we evaluated the distribution 

of HAP-related cancer and noncancer 

risk from the Cyanide Chemicals 

Manufacturing source category across 

different demographic groups within the 

populations living near facilities.24

The results of the demographic 

analysis are summarized in Table 2 

below. These results, for various 

demographic groups, are based on the 

estimated risk from actual emissions 

levels for the population living within 

50 km of the facilities. 

TABLE 2—CYANIDE CHEMICALS MANUFACTURING DEMOGRAPHIC RISK ANALYSIS RESULTS

Nationwide 

Population 

with cancer 

risk at or 

above 1-in-1 

million due to 

cyanide 

chemicals 

manufacturing 

Population 

with chronic HI 

above 1 due 

to cyanide 

chemicals 

manufacturing 

Total Population ........................................................................................................................... 317,746,049 61,653 0 

Race by Percent 

White ............................................................................................................................................ 62 73 ........................

All Other Races ........................................................................................................................... 38 27 ........................

Race by Percent 

White ............................................................................................................................................ 62 73 ........................

African American ......................................................................................................................... 12 19 ........................

Native American .......................................................................................................................... 0.8 0.4 ........................

Other and Multiracial ................................................................................................................... 7 4 ........................

Ethnicity by Percent 

Hispanic ....................................................................................................................................... 18 3 ........................

Non-Hispanic ............................................................................................................................... 82 97 ........................

Income by Percent 

Below Poverty Level .................................................................................................................... 14 16 ........................

Above Poverty Level .................................................................................................................... 86 84 ........................

Education by Percent 

Over 25 and without High School Diploma ................................................................................. 14 16 ........................

Over 25 and with a High School Diploma ................................................................................... 86 84 ........................

The results of the Cyanide Chemicals 

Manufacturing source category 

demographic analysis indicate that 

emissions from the source category 

expose approximately 61,653 people to 

a cancer risk at or above 1-in-1 million 

and nobody to a chronic noncancer 

TOSHI greater than 1. The percentages 

of the at-risk population in the White, 

African American, Below Poverty, and 

Over 25 without High School Diploma 

demographic groups are greater than 

their respective nationwide percentages. 

The methodology and the results of 

the demographic analysis are presented 

in a technical report, Risk and 

Technology Review—Analysis of 

Demographic Factors for Populations 

Living Near Cyanide Chemicals 

Manufacturing, available in the docket 

for this action. 

C. What are our proposed decisions 

regarding risk acceptability, ample 

margin of safety, and adverse 

environmental effect? 

1. Risk Acceptability 

As explained in section II.A of this 

preamble, the EPA sets standards under 

3924 Federal Register / Vol. 86, No. 10 / Friday, January 15, 2021 / Proposed Rules 

25https://www.epa.gov/electronic-reporting-airemissions/electronic-reporting-tool-ert. 

26See Draft Form_5900–485_Subpart_YY_

Cyanide_Draft_Periodic_Report_Template_

Proposal.xlsm, available at Docket ID No. EPA–HQ– 

OAR–2020–0532. 

CAA section 112(f)(2) using ‘‘a two-step 

standard-setting approach, with an 

analytical first step to determine an 

’acceptable risk’ that considers all 

health information, including risk 

estimation uncertainty, and includes a 

presumptive limit on maximum 

individual risk (MIR) of approximately 

1-in-10 thousand.’’ (54 FR 38045, 

September 14, 1989). The EPA weighed 

all health risk measures and 

information, including science policy 

assumptions and estimation 

uncertainties, in determining whether 

risk posed by emissions from the source 

category is acceptable. 

The estimated maximum cancer risk 

for inhalation exposure to actual and 

allowable emissions from the Cyanide 

Chemicals Manufacturing source 

category was 5-in-1 million, 20 times 

below 100-in-1 million, which is the 

presumptive upper limit of acceptable 

risk. The EPA estimates emissions from 

the category would result in a cancer 

incidence of 0.004 excess cancer cases 

per year, or one case every 250 years. 

Inhalation exposures to HAP associated 

with chronic noncancer health effects 

result in a TOSHI of 1 based on actual 

and allowable emissions, an exposure 

level that the EPA has determined is 

without appreciable risk of adverse 

health effects. Exposures to HAP 

associated with acute noncancer health 

effects also are below levels of health 

concern with no HAP exposures 

resulting in an HQ greater than 1 based 

upon the 1-hour REL. 

Maximum cancer risk due to ingestion 

exposures, estimated using healthprotective risk screening assumptions, is 

below 1-in-1 million for the Tier 2 

farmer exposure scenario. Tier 2 

screening analyses of mercury exposure 

due to fish ingestion determined that 

the maximum HQ for mercury would be 

less than 1 as explained in section 

III.C.4 of this preamble. 

Considering all of the health risk 

information and factors discussed 

above, as well as the uncertainties 

discussed in section III of this preamble, 

we propose that the risks posed by 

emissions from the Cyanide Chemicals 

Manufacturing source category are 

acceptable. 

2. Ample Margin of Safety Analysis 

As directed by CAA section 112(f)(2), 

we conducted an analysis to determine 

whether the current emissions standards 

provide an ample margin of safety to 

protect public health. Under the ample 

margin of safety analysis, we evaluated 

the cost and feasibility of available 

control technologies and other measures 

(including the controls, measures, and 

costs reviewed under the technology 

review) that could be applied to this 

source category to further reduce the 

risks (or potential risks) due to 

emissions of HAP from the source 

category. In light of the low cancer and 

noncancer risk posed to individuals 

exposed to HAP emitted from this 

source category and lack of additional 

control technologies, we are proposing 

to conclude that the existing standards 

under the NESHAP provide an ample 

margin of safety to protect public health. 

3. Adverse Environmental Effect 

Based on the results of our 

environmental risk screening analysis, 

we do not anticipate an adverse 

environmental effect as a result of HAP 

emissions from this source category. 

Therefore, the EPA is proposing that it 

is not necessary to set a more stringent 

standard to prevent, taking into 

consideration costs, energy, safety, and 

other relevant factors, an adverse 

environmental effect. 

D. What are the results and proposed 

decisions based on our technology 

review? 

As part of the technology review, we 

identified a previously unregulated 

process, and are proposing a MACT 

standard for the process under CAA 

section 112(d)(2) and (3), as described in 

Section IV.A of this preamble, above. 

We did not identify any developments 

in processes, practices, or control 

technologies for cyanide chemicals 

manufacturing facilities during our 

analysis for this proposal. Facilities 

subject to this NESHAP use flares to 

control emissions from point sources 

and LDAR programs to address 

emissions from equipment leaks. As 

discussed in the memorandum titled 

Technical Support Document for the 

Cyanide Chemicals Manufacturing 

NESHAP Residual Risk and Technology 

Review Proposal, we did not identify 

any developments in these technologies 

during our technology review. 

E. What other actions are we proposing? 

In addition to the proposed actions 

described above, we are proposing 

additional revisions to the NESHAP. We 

are proposing revisions to the SSM 

provisions of the MACT rule in order to 

ensure that they are consistent with the 

decision in Sierra Club v. EPA, 551 F. 

3d 1019 (DC Cir. 2008), in which the 

court vacated two provisions that 

exempted sources from the requirement 

to comply with otherwise applicable 

CAA section 112(d) emission standards 

during periods of SSM. We note that for 

the Cyanide Chemicals Manufacturing 

source category, the NESHAP currently 

does not include an exemption for SSM 

events, and already includes standards 

that apply at all times, including 

periods of SSM. Therefore, we have 

determined that the NESHAP is already 

consistent with the court decision 

mentioned above. However, we are 

making revisions to the MACT rule at 40 

CFR 63.1108 through 40 CFR 63.1112 to 

ensure this is clearly and consistently 

communicated throughout and no 

confusion results from referenced 

subparts associated with the GMACT 

that may contain SSM exemptions for 

other source categories. We also are 

proposing other changes to add 

electronic reporting. Our analyses and 

proposed changes related to these issues 

are discussed below. 

Electronic Reporting. The EPA is 

proposing that owners and operators of 

cyanide chemicals manufacturing 

facilities submit electronic copies of 

required notifications of compliance, 

performance test reports, and periodic 

reports through the EPA’s Central Data 

Exchange (CDX) using the Compliance 

and Emissions Data Reporting Interface 

(CEDRI). A description of the electronic 

data submission process is provided in 

the memorandum, Electronic Reporting 

Requirements for New Source 

Performance Standards (NSPS) and 

National Emission Standards for 

Hazardous Air Pollutants (NESHAP) 

Rules, available in the docket for this 

action. The proposed rule requires that 

performance test results collected using 

test methods that are supported by the 

EPA’s Electronic Reporting Tool (ERT) 

as listed on the ERT website 25 at the 

time of the test be submitted in the 

format generated through the use of the 

ERT or an electronic file consistent with 

the xml schema on the ERT website, and 

other performance test results be 

submitted in portable document format 

(PDF) using the attachment module of 

the ERT. The proposed rule requires 

that Notification of Compliance Status 

(NOCS) be submitted as a PDF upload 

in CEDRI. 

For periodic reports, the proposed 

rule requires that owners and operators 

use the appropriate spreadsheet 

template to submit information to 

CEDRI. A draft version of the proposed 

template for these reports is included in 

the docket for this action.26 The EPA 

specifically requests comment on the 

content, layout, and overall design of 

the template. 

Additionally, the EPA has identified 

two broad circumstances in which 

Federal Register / Vol. 86, No. 10 / Friday, January 15, 2021 / Proposed Rules 3925 

27EPA’s Final Plan for Periodic Retrospective 

Reviews, August 2011. Available at: https://

www.regulations.gov/document?D=EPA-HQ-OA2011-0156-0154. 

28E-Reporting Policy Statement for EPA 

Regulations, September 2013. Available at: https:// 

www.epa.gov/sites/production/files/2016-03/ 

documents/epa-ereporting-policy-statement-2013- 

09-30.pdf. 

29 Digital Government: Building a 21st Century 

Platform to Better Serve the American People, May 

2012. Available at: https://

obamawhitehouse.archives.gov/sites/default/files/ 

omb/egov/digital-government/digitalgovernment.html. 

electronic reporting extensions may be 

provided. These circumstances are (1) 

outages of the EPA’s CDX or CEDRI 

which preclude an owner or operator 

from accessing the system and 

submitting required reports and (2) force 

majeure events, which are defined as 

events that will be or have been caused 

by circumstances beyond the control of 

the affected facility, its contractors, or 

any entity controlled by the affected 

facility that prevent an owner or 

operator from complying with the 

requirement to submit a report 

electronically. Examples of force 

majeure events are acts of nature, acts 

of war or terrorism, or equipment failure 

or safety hazards beyond the control of 

the facility. The EPA is providing these 

potential extensions to protect owners 

and operators from noncompliance in 

cases where they cannot successfully 

submit a report by the reporting 

deadline for reasons outside of their 

control. In both circumstances, the 

decision to accept the claim of needing 

additional time to report is within the 

discretion of the Administrator, and 

reporting should occur as soon as 

possible. 

The electronic submittal of the reports 

addressed in this proposed rulemaking 

will increase the usefulness of the data 

contained in those reports, is in keeping 

with current trends in data availability 

and transparency, will further assist in 

the protection of public health and the 

environment, will improve compliance 

by facilitating the ability of regulated 

facilities to demonstrate compliance 

with requirements and by facilitating 

the ability of delegated state, local, 

tribal, and territorial air agencies and 

the EPA to assess and determine 

compliance, and will ultimately reduce 

burden on regulated facilities, delegated 

air agencies, and the EPA. Electronic 

reporting also eliminates paper-based, 

manual processes, thereby saving time 

and resources, simplifying data entry, 

eliminating redundancies, minimizing 

data reporting errors, and providing data 

quickly and accurately to the affected 

facilities, air agencies, the EPA, and the 

public. Moreover, electronic reporting is 

consistent with the EPA’s plan 27 to 

implement Executive Order 13563 and 

is in keeping with the EPA’s Agencywide policy 28 developed in response to 

the White House’s Digital Government 

Strategy.29 For more information on the 

benefits of electronic reporting, see the 

memorandum, Electronic Reporting 

Requirements for New Source 

Performance Standards (NSPS) and 

National Emission Standards for 

Hazardous Air Pollutants (NESHAP) 

Rules, referenced earlier in this section. 

F. What compliance dates are we 

proposing? 

The EPA is proposing that existing 

affected sources and affected sources 

that commenced construction or 

reconstruction on or before January 15, 

2021, must comply with the proposed 

process wastewater standards no later 

than 365 days after the effective date of 

the final rule and all of the other 

amendments no later than 180 days after 

the effective date of the final rule. The 

final action is not expected to be a 

‘‘major rule’’ as defined by 5 U.S.C. 

804(2), so the effective date of the final 

rule will be the promulgation date as 

specified in CAA section 112(d)(10). For 

existing sources, we are proposing a 

change that would impact ongoing 

compliance requirements for 40 CFR 

part 63, subpart YY. As discussed 

elsewhere in this preamble, we are 

proposing to change the requirements 

for SSM by removing references to 

exemptions in other subparts. Our 

experience with similar industries 

shows that this sort of regulated facility 

generally requires a time period of 180 

days to read and understand the 

amended rule requirements; to evaluate 

their operations to ensure that they can 

meet the standards during periods of 

startup and shutdown as defined in the 

rule and make any necessary 

adjustments; and to update their 

operations to reflect the revised 

requirements. 

From our assessment of the timeframe 

needed for compliance with the revised 

requirements, the EPA considers a 

period of 180 days to be the most 

expeditious compliance period 

practicable, and, thus, is proposing that 

existing affected sources be in 

compliance with this regulation’s 

revised requirements within 180 days of 

the regulation’s effective date. We solicit 

comment on this proposed compliance 

period, and we specifically request 

submission of information from sources 

in this source category regarding 

specific actions that would need to be 

undertaken to comply with the 

proposed amended requirements, 

including the proposed amendments 

related to recordkeeping and reporting 

and the time needed to make the 

adjustments for compliance with them. 

We note that information provided may 

result in changes to the proposed 

compliance date; however, we expect 

the proposed compliance time to be 

sufficient given that cyanide chemicals 

manufacturing facilities are already 

subject to standards during these 

periods. We are proposing that facilities 

will have 1 year to comply with the 

proposed process wastewater standards 

for existing sources. We note that we do 

not expect the proposed wastewater 

standards for existing sources to require 

installation of any additional controls. 

We believe that all affected sources are 

already complying with the proposed 

wastewater requirements or 

requirements that are substantively 

identical. We are proposing that 

facilities must comply within 365 days 

in order to provide time to evaluate 

wastewater operations, perform 

compliance calculations, and adjust 

plans and reports as necessary. We are 

seeking comment on the assumption 

that facilities will not need to install 

additional add-on controls and whether 

facilities would require more or less 

time to comply with the proposed 

process wastewater requirements. 

Affected sources that commence 

construction or reconstruction after 

January 15, 2021, must comply with all 

requirements of the subpart, including 

the amendments being proposed, no 

later than the effective date of the final 

rule or upon startup, whichever is later. 

All affected facilities would have to 

continue to meet the current 

requirements of 40 CFR part 63, subpart 

YY, until the applicable compliance 

date of the amended rule. 

V. Summary of Cost, Environmental, 

and Economic Impacts 

A. What are the affected sources? 

There are 13 cyanide chemicals 

manufacturing facilities currently 

operating as major sources of HAP 

subject to the proposed amendments. A 

list of facilities that are currently subject 

to the MACT standards is available in 

the memorandum titled Technical 

Support Document for the Cyanide 

Chemicals Manufacturing NESHAP 

Residual Risk and Technology Review 

Proposal, available in Docket ID No. 

EPA–HQ–OAR–2020–0532. 

B. What are the air quality impacts? 

We do not anticipate that the 

proposed amendments to this subpart 

will impact air quality. We are not 

proposing changes to the standard that 

3926 Federal Register / Vol. 86, No. 10 / Friday, January 15, 2021 / Proposed Rules 

will result in additional emission 

reductions beyond the levels already 

achieved by the NESHAP. 

C. What are the cost impacts? 

The proposed amendments will have 

a limited cost impact on affected 

facilities. Total estimated costs are 

$47,527 based on a $3,656 per facility 

cost for all 13 facilities. The costs result 

from reading and understanding rule 

requirements and adjusting compliance 

plans based on the rule proposal. All 

costs are one-time expenses expected to 

occur in the first year after the rule is 

finalized. Costs are based on Agency 

knowledge and experience with the 

NESHAP program, related ICRs, and 

Bureau of Labor Statistics data. 

D. What are the economic impacts? 

Economic impact analyses focus on 

changes in market prices and output 

levels. If changes in market prices and 

output levels in the primary markets are 

significant enough, impacts on other 

markets may also be examined. Both the 

magnitude of costs associated with the 

proposed requirements and the 

distribution of these costs among 

affected facilities can have a role in 

determining how the market will change 

in response to a proposed rule. 

Economic costs to owners of cyanide 

chemicals manufacturing facilities were 

measured in present value (PV) total 

costs and equivalent annual value (EAV) 

costs. All cyanide chemicals 

manufacturing facilities were estimated 

to have similar costs. All costs are 

presented in 2019 dollars. See section 

V.C of this preamble for additional 

information on costs. 

PV total costs and EAV costs were 

measured at the 3 percent and 7 percent 

discount rates. The duration of analysis 

was 8 years. Per facility PV total cost 

estimate is $3,656 at the 3 percent and 

7 percent discount rates. The similarity 

in both discount rates is due to the costs 

all occuring in the first year after the 

rule is finalized. EAV costs per facility 

are measured to be $521 and $612 at the 

3 percent and 7 percent discount rates, 

respectively. Combined total PV cost of 

the proposed requirements for all 

facilities is measured to be $47,527 at 

the 3 percent and 7 percent discount 

rates. The similarity in both discount 

rates is due to the costs all coming in 

the first year that the rule will be 

finalized. Combined EAV costs of the 

proposed requirements for all facilities 

are measured to be $6,771 and $7,959 at 

the 3 percent and 7 percent discount 

rates, respectively. 

As required by the Regulatory 

Flexibility Act (RFA), we performed an 

analysis to determine if any small 

entities would be unduly burdened by 

the proposed amendments. We 

determined that all facilities subject to 

the NESHAP are owned by large parent 

entities based on Small Business 

Administration standards. No 

significant economic impacts from the 

proposed amendments are anticipated 

because the PV and EAV costs 

associated with the proposed revisions 

are minimal. 

E. What are the benefits? 

As discussed in section V.B of this 

preamble, we do not anticipate the 

proposed amendments to this subpart to 

impact air quality. The electronic 

submittal of the reports addressed in 

this proposed rulemaking will increase 

the usefulness of the data contained in 

those reports, is in keeping with current 

trends in data availability and 

transparency, will further assist in the 

protection of public health and the 

environment, will improve compliance 

by facilitating the ability of regulated 

facilities to demonstrate compliance 

with requirements, and by facilitating 

the ability of delegated state, local, 

tribal, and territorial air agencies and 

the EPA to assess and determine 

compliance, and will ultimately reduce 

burden on regulated facilities, delegated 

air agencies, and the EPA. Electronic 

reporting also eliminates paper-based, 

manual processes, thereby saving time 

and resources, simplifying data entry, 

eliminating redundancies, minimizing 

data reporting errors, and providing data 

quickly and accurately to the affected 

facilities, air agencies, the EPA, and the 

public. 

VI. Request for Comments 

We solicit comments on this proposed 

action. In addition to general comments 

on this proposed action, we are also 

interested in additional data that may 

improve the risk assessments and other 

analyses. We are specifically interested 

in receiving any improvements to the 

data used in the site-specific emissions 

profiles used for risk modeling. Such 

data should include supporting 

documentation in sufficient detail to 

allow characterization of the quality and 

representativeness of the data or 

information. Section VII of this 

preamble provides more information on 

submitting data. 

VII. Submitting Data Corrections 

The site-specific emissions profiles 

used in the source category risk and 

demographic analyses and instructions 

are available for download on the RTR 

website at https://www.epa.gov/ 

stationary-sources-air-pollution/acetalresins-acrylic-modacrylic-fibers-carbonblack-hydrogen. The data files include 

detailed information for each HAP 

emissions release point for the facilities 

in the source category. 

If you believe that the data are not 

representative or are inaccurate, please 

identify the data in question, provide 

your reason for concern, and provide 

any ‘‘improved’’ data that you have, if 

available. When you submit data, we 

request that you provide documentation 

of the basis for the revised values to 

support your suggested changes. To 

submit comments on the data 

downloaded from the RTR website, 

complete the following steps: 

1. Within this downloaded file, enter 

suggested revisions to the data fields 

appropriate for that information. 

2. Fill in the commenter information 

fields for each suggested revision (i.e., 

commenter name, commenter 

organization, commenter email address, 

commenter phone number, and revision 

comments). 

3. Gather documentation for any 

suggested emissions revisions (e.g., 

performance test reports, material 

balance calculations). 

4. Send the entire downloaded file 

with suggested revisions in Microsoft®

Access format and all accompanying 

documentation to Docket ID No. EPA– 

HQ–OAR–2020–0532 (through the 

method described in the ADDRESSES

section of this preamble). 

5. If you are providing comments on 

a single facility or multiple facilities, 

you need only submit one file for all 

facilities. The file should contain all 

suggested changes for all sources at that 

facility (or facilities). We request that all 

data revision comments be submitted in 

the form of updated Microsoft® Excel 

files that are generated by the 

Microsoft® Access file. These files are 

provided on the project website at 

https://www.epa.gov/stationary-sourcesair-pollution/acetal-resins-acrylicmodacrylic-fibers-carbon-blackhydrogen. 

VIII. Statutory and Executive Order 

Reviews 

Additional information about these 

statutes and Executive Orders can be 

found at https://www.epa.gov/lawsregulations/laws-and-executive-orders. 

A. Executive Orders 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 OMB for review. 

Federal Register / Vol. 86, No. 10 / Friday, January 15, 2021 / Proposed Rules 3927 

B. Executive Order 13771: Reducing 

Regulations and Controlling Regulatory 

Costs 

This action is not expected to be an 

Executive Order 13771 regulatory action 

because this action is not significant 

under Executive Order 12866. 

C. Paperwork Reduction Act (PRA) 

The information collection activities 

in this proposed rule have been 

submitted to the OMB under the PRA. 

The Information Collection Request 

(ICR) document that the EPA prepared 

has been assigned EPA ICR number 

2678.01. You can find a copy of the ICR 

in the docket for this rule, and it is 

briefly summarized here. 

The EPA is proposing amendments 

that revise provisions pertaining to 

emissions during periods of SSM, add 

requirements for electronic reporting of 

NOCS, periodic reports, and 

performance test results, and make other 

minor clarifications and corrections. 

This information will be collected to 

assure compliance with the Cyanide 

Chemicals Manufacturing NESHAP. 

Respondents/affected entities: 

Owners or operators of cyanide 

chemicals manufacturing facilities. 

Respondent’s obligation to respond: 

Mandatory (40 CFR part 63, subpart 

YY). 

Estimated number of respondents: 13 

(assumes no new respondents over the 

next 3 years). 

Frequency of response: Initially, 

occasionally, and annually. 

Total estimated burden: 160 hours 

(per year) to comply with all of the 

requirements in the NESHAP. Burden is 

defined at 5 CFR 1320.3(b). 

Total estimated cost: $15,800 (per 

year), including no annualized capital 

or operation and maintenance costs, to 

comply with all of the requirements in 

the NESHAP. 

An agency may not conduct or 

sponsor, and a person is not required to 

respond to, a collection of information 

unless it displays a currently valid OMB 

control number. The OMB control 

numbers for the EPA’s regulations in 40 

CFR are listed in 40 CFR part 9. 

Submit your comments on the 

Agency’s need for this information, the 

accuracy of the provided burden 

estimates, and any suggested methods 

for minimizing respondent burden to 

the EPA using the docket identified at 

the beginning of this rule. You may also 

send your ICR-related comments to 

OMB’s Office of Information and 

Regulatory Affairs via email to OIRA_

submission@omb.eop.gov, Attention: 

Desk Officer for the EPA. Since OMB is 

required to make a decision concerning 

the ICR between 30 and 60 days after 

receipt, OMB must receive comments no 

later than February 16, 2021. The EPA 

will respond to any ICR-related 

comments in the final rule. 

D. 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. This action will not 

impose any requirements on small 

entities. There are no small entities 

among the eight ultimate parent 

companies impacted by this proposed 

action given the Small Business 

Administration small business size 

definition for this industry (1,000 

employees or greater for NAICS 

325180—Other Basic Inorganic 

Chemical Manufacturing), and no 

significant economic impact on any of 

these entities. 

E. Unfunded Mandates Reform Act 

(UMRA) 

This action does not contain an 

unfunded mandate of $100 million or 

more as described in UMRA, 2 U.S.C. 

1531–1538, and does not significantly or 

uniquely affect small governments. The 

action imposes no enforceable duty on 

any state, local, or tribal governments or 

the private sector. 

F. 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. 

G. 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 cyanide 

chemicals manufacturing production 

facilities that have been identified as 

being affected by this proposed action 

are owned or operated by tribal 

governments or located within tribal 

lands. Thus, Executive Order 13175 

does not apply to this action. 

H. Executive Order 13045: Protection of 

Children From Environmental Health 

Risks and Safety Risks 

This action is not subject to Executive 

Order 13045 because the EPA does not 

believe the environmental health risks 

or safety risks addressed by this action 

present a disproportionate risk to 

children. This action’s health and risk 

assessments are contained in section 

IV.B of this preamble and the document, 

Residual Risk Assessment for the 

Cyanide Chemicals Manufacturing 

Source Category in Support of the Risk 

and Technology Review 2020 Proposed 

Rule, which is available in the docket 

for this rulemaking. 

I. 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 

significant regulatory action under 

Executive Order 12866. 

J. National Technology Transfer and 

Advancement Act (NTTAA) 

This action involves technical 

standards. Therefore, the EPA 

conducted a search to identify 

potentially applicable voluntary 

consensus standards. However, the 

Agency identified no such standards. A 

thorough summary of the search and 

results are included in the 

memorandum titled Voluntary 

Consensus Standard Results for Cyanide 

Chemicals Manufacturing Residual Risk 

and Technology Review, which is 

available in the docket for this action. 

K. Executive Order 12898: Federal 

Actions To Address Environmental 

Justice in Minority Populations and 

Low-Income Populations 

The EPA believes that this action does 

not have disproportionately high and 

adverse human health or environmental 

effects on minority populations, lowincome populations, and/or indigenous 

peoples, as specified in Executive Order 

12898 (59 FR 7629, February 16, 1994). 

The documentation for this decision 

is contained in section IV.B of this 

preamble and in the technical report, 

Risk and Technology Review—Analysis 

of Demographic Factors for Populations 

Living Near Cyanide Chemicals 

Manufacturing Facilities, available in 

the docket for this action. 

List of Subjects in 40 CFR Part 63 

Environmental protection, Air 

pollution control, Hazardous 

substances, Reporting and 

recordkeeping requirements. 

Andrew Wheeler, 

Administrator. 

[FR Doc. 2021–00374 Filed 1–14–21; 8:45 am] 

BILLING CODE 6560–50–P