National Emission Standards for Hazardous Air Pollutant Emissions: Group I Polymers and Resins (Polysulfide Rubber Production, Ethylene Propylene Rubber Production, Butyl Rubber Production, Neoprene Production); National Emission Standards for Hazardous Air Pollutants for Epoxy Resins Production and Non-Nylon Polyamides Production; National Emission Standards for Hazardous Air Pollutants for Source Categories: Generic Maximum Achievable Control Technology Standards (Acetal Resins Production and Hydrogen Fluoride Production), 70543-70558 [E7-24076]
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Federal Register / Vol. 72, No. 238 / Wednesday, December 12, 2007 / Proposed Rules
ENVIRONMENTAL PROTECTION
AGENCY
40 CFR Part 63
[EPA–HQ–OAR–2007–0211; FRL–8505–1]
RIN 2060–AO16
National Emission Standards for
Hazardous Air Pollutant Emissions:
Group I Polymers and Resins
(Polysulfide Rubber Production,
Ethylene Propylene Rubber
Production, Butyl Rubber Production,
Neoprene Production); National
Emission Standards for Hazardous Air
Pollutants for Epoxy Resins
Production and Non-Nylon Polyamides
Production; National Emission
Standards for Hazardous Air Pollutants
for Source Categories: Generic
Maximum Achievable Control
Technology Standards (Acetal Resins
Production and Hydrogen Fluoride
Production)
Environmental Protection
Agency (EPA).
ACTION: Proposed rule.
AGENCY:
SUMMARY: This proposed rule requests
public comment on the residual risk and
technology reviews for eight industrial
source categories regulated by four
national emission standards for
hazardous air pollutants (HAP). The
eight industrial source categories and
the four national emission standards are
listed in Table 3 of this preamble. The
underlying national emission standards
that are under review in this action limit
and control HAP.
We are proposing that no revisions to
the national emission standards
regulating the eight source categories
listed in Table 3 of this preamble are
required at this time under section
112(f)(2) or 112(d)(6) of the Clean Air
Act.
DATES: Comments. Comments must be
received on or before February 11, 2008.
Public Hearing. If anyone contacts
EPA requesting to speak at a public
hearing by December 27, 2007, a public
hearing will be held on January 11,
2008.
Submit your comments,
identified by Docket ID No. EPA–HQ–
OAR–2007–0211, by one of the
following methods:
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ADDRESSES:
• www.regulations.gov. Follow the
on-line instructions for submitting
comments.
• E-mail: a-and-r-Docket@epa.gov.
• Fax: (202) 566–1741.
• Mail: U.S. Postal Service, send
comments to: EPA Docket Center
(2822T), Docket ID No. EPA–HQ–OAR–
2007–0211, 1200 Pennsylvania Avenue,
NW., Washington, DC 20460. Please
include a total of two copies.
• Hand Delivery: In person or by
courier, deliver comments to: EPA
Docket Center (2822T), EPA West
Building, Room 3334, 1301 Constitution
Ave., NW., Washington, DC 20004. Such
deliveries are only accepted during the
Docket’s normal hours of operation, and
special arrangements should be made
for deliveries of boxed information.
Please include a total of two copies.
Instructions: Direct your comments to
Docket ID No. EPA–HQ–OAR–2007–
0211. If commenting on the data in the
Risk and Technology Review (RTR)
database, please format your comments
as described in section III and IV of this
preamble. EPA’s policy is that all
comments received will be included in
the public docket without change and
may be made available online at
www.regulations.gov, including any
personal information provided, unless
the comment includes information
claimed to be confidential business
information (CBI) or other information
whose disclosure is restricted by statute.
Do not submit information that you
consider to be CBI or otherwise
protected through www.regulations.gov
or e-mail. The www.regulations.gov Web
site is an ‘‘anonymous access’’ system,
which means EPA will not know your
identity or contact information unless
you provide it in the body of your
comment. If you send an e-mail
comment directly to EPA without going
through 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, EPA recommends that you
include your name and other contact
information in the body of your
comment and with any disk or CD–ROM
you submit. If EPA cannot read your
comment due to technical difficulties
and cannot contact you for clarification,
70543
EPA may not be able to consider your
comment. Electronic files should avoid
the use of special characters, any form
of encryption, and be free of any defects
or viruses. For additional information
about EPA’s public docket visit the EPA
Docket Center homepage at https://
www.epa.gov/epahome/dockets.htm.
Docket: All documents in the docket
are listed in the www.regulations.gov
index. Although listed in the index,
some information is not publicly
available, e.g., CBI or other information
whose disclosure is restricted by statute.
Certain other material, such as
copyrighted material, will be publicly
available only in hard copy. Publicly
available docket materials are available
either electronically in
www.regulations.gov or in hard copy at
the EPA Docket Center, Docket ID No.
EPA–HQ–OAR–2007–0211, EPA West
Building, Room 3334, 1301 Constitution
Avenue, NW., Washington, DC. The
Public Reading Room is open from 8:30
a.m. to 4:30 p.m., Monday through
Friday, excluding legal holidays. The
telephone number for the Public
Reading Room is (202) 566–1744, and
the telephone number for the EPA
Docket Center is (202) 566–1742.
For
questions about this proposed action,
contact Ms. Mary Tom Kissell, Office of
Air Quality Planning and Standards,
Sector Policies and Programs Division,
Coatings and Chemicals Group (E143–
01), U.S. Environmental Protection
Agency, Research Triangle Park, NC
27711; telephone number: (919) 541–
4516; fax number: (919) 685–3219; and
e-mail address: kissell.mary@epa.gov.
For specific information regarding the
modeling methodology, contact Ms.
Elaine Manning, Office and Air Quality
Planning and Standards, Health and
Environmental Impacts Division, Sector
Based Assessment Group (C539–02),
U.S. Environmental Protection Agency,
Research Triangle Park, NC 27711;
telephone number: (919) 541–5499; fax
number: (919) 541–0840; and e-mail
address: manning.elaine@epa.gov. For
information about the applicability of
these four national emission standards
for hazardous air pollutants (NESHAP)
to a particular entity, contact the
appropriate person listed in Table 1 to
this preamble.
FOR FURTHER INFORMATION CONTACT:
TABLE 1.—LIST OF EPA CONTACTS FOR GROUP I POLYMERS AND RESINS, GROUP II POLYMERS AND RESINS, ACETAL
RESINS PRODUCTION, AND HYDROGEN FLUORIDE PRODUCTION
NESHAP for:
OECA Contact 1
Polymers and Resins, Group I ....
Scott Throwe (202) 564–7013, throwe.scott@epa.gov
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OAQPS Contact 2
Sfmt 4702
David
Markwordt
(919)
markwordt.david@epa.gov.
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TABLE 1.—LIST OF EPA CONTACTS FOR GROUP I POLYMERS AND RESINS, GROUP II POLYMERS AND RESINS, ACETAL
RESINS PRODUCTION, AND HYDROGEN FLUORIDE PRODUCTION—Continued
NESHAP for:
OECA Contact 1
Polymers and Resins, Group II ...
Scott Throwe (202) 564–7013, throwe.scott@epa.gov
Acetal Resins Production ............
Marcia Mia (202) 564–7042, mia.marcia@epa.gov ....
Hydrogen Fluoride Production ....
Marcia Mia (202) 564–7042, mia.marcia@epa.gov ....
1 OECA
OAQPS Contact 2
Randy McDonald (919) 541–5402,
mcdonald.randy@epa.gov.
David Markwordt (919) 541–0837,
markwordt.david@epa.gov.
Bill Neuffer (919) 541–5435, Neuffer.bill@epa.gov.
stands for the EPA’s Office of Enforcement and Compliance Assurance.
stands for EPA’s Office of Air Quality Planning and Standards.
2 OAQPS
Regulated
Entities. The eight regulated industrial
source categories that are the subject of
today’s proposal are listed in Table 2 to
this preamble. Table 2 is not intended
to be exhaustive, but rather provides a
SUPPLEMENTARY INFORMATION:
guide for readers regarding entities
likely to be affected by the proposed
action for the source categories listed.
These standards, and any changes
considered in this rulemaking, would be
directly applicable to sources as a
Federal program. Thus, Federal, State,
local, and tribal government entities are
not affected by this proposed rule. The
regulated categories affected by this
action include:
TABLE 2.—NESHAP FOR EIGHT INDUSTRIAL SOURCE CATEGORIES
NAICS 1 Code
Category
Butyl Rubber Production ..........................................................................................................................................
Ethylene-Propylene Rubber Production ..................................................................................................................
Polysulfide Rubber Production ................................................................................................................................
Neoprene Production ...............................................................................................................................................
Epoxy Resins Production ........................................................................................................................................
Non-nylon Polyamides Production ..........................................................................................................................
Acetal Resins Production ........................................................................................................................................
Hydrogen Fluoride Production .................................................................................................................................
1 North
MACT 2 Code
325212
325212
325212
325212
325211
325211
325211
325120
1307
1313
1332
1320
1312
1322
1301
1409
American Industry Classification System.
Achievable Control Technology.
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2 Maximum
To determine whether your facility
would be affected, you should examine
the applicability criteria in the
appropriate NESHAP. If you have any
questions regarding the applicability of
any of these NESHAP, please contact
the appropriate person listed in Table 1
of this preamble in the preceding FOR
FURTHER INFORMATION CONTACT section.
Submitting Comments/CBI. Direct
your comments to Docket ID No. EPA–
HQ–OAR–2007–0211. If commenting on
changes to the RTR database, please
submit your comments in the format
described in sections III and IV of this
preamble. Do not submit CBI to EPA
through www.regulations.gov or e-mail.
Instead, send or deliver information
identified as CBI only to the following
address: Mr. Roberto Morales, OAQPS
Document Control Officer (C404–02),
U.S. Environmental Protection Agency,
Office of Air Quality Planning and
Standards, Research Triangle Park, NC
27711, Attention Docket ID No. EPA–
HQ–OAR–2007–0211. Clearly mark the
part or all of the information that you
claim to be CBI. For CBI information on
a disk or CD–ROM that you mail to Mr.
Morales, mark the outside of the disk or
CD–ROM as CBI and then identify
electronically within the disk or CD–
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ROM the specific information that is
claimed as CBI.
In addition to one complete version of
the comment that includes information
claimed as CBI, a copy of the comment
that does not contain the information
claimed as CBI must be submitted for
inclusion in the public docket. If you
submit a CD–ROM or disc that does not
contain CBI, mark the outside of the
disk or CD–ROM clearly that it does not
contain CBI. Information not marked as
CBI will be included in the public
docket and EPA’s electronic public
docket without prior notice.
If you have any questions about CBI
or the procedures for claiming CBI,
please consult the person identified in
the FOR FURTHER INFORMATION CONTACT
section. Information marked as CBI will
not be disclosed except in accordance
with procedures set forth in 40 CFR part
2.
Worldwide Web (WWW). In addition
to being available in the docket, an
electronic copy of today’s proposed
action will also be available on the
WWW through the Technology Transfer
Network (TTN). Following signature, a
copy of the proposed action will be
posted on the TTN(s policy and
guidance page for newly proposed or
promulgated rules at the following
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address: https://www.epa.gov/ttn/oarpg/.
The TTN provides information and
technology exchange in various areas of
air pollution control.
As discussed in more detail in
sections III and IV of this preamble,
additional information is available on
the Risk and Technology Review Phase
II webpage at https://www.epa.gov/ttn/
atw/rrisk/rtrpg.html. This information
includes source category descriptions
and detailed emissions and other data
that were used as inputs to the risk
assessments.
Public Hearing. If a public hearing is
held, it will begin at 10 a.m. and will
be held at EPA’s campus in Research
Triangle Park, North Carolina, or at an
alternate facility nearby. Persons
interested in presenting oral testimony
or inquiring as to whether a public
hearing is to be held should contact Ms.
Mary Tom Kissell, Office of Air Quality
Planning and Standards, Sector Policies
and Programs Division, Coatings and
Chemicals Group (E143–01), U.S.
Environmental Protection Agency,
Research Triangle Park, NC 27711;
telephone number: (919) 541–4516.
Outline. The information presented in
this preamble is organized as follows:
I. Background
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A. What is the statutory authority for this
action?
B. Overview of the Four NESHAP
C. How did we estimate risk posed by the
eight source categories?
D. What are the conclusions of the risk
review?
E. What are the conclusions of the
technology review?
II. Proposed Action
III. How do I access and review the facilityspecific data?
IV. How do I submit suggested data
corrections?
V. Statutory and Executive Order Reviews
A. Executive Order 12866, Regulatory
Planning and Review
B. Paperwork Reduction Act
C. Regulatory Flexibility Act
D. Unfunded Mandates Reform Act
E. Executive Order 13132, Federalism
F. Executive Order 13175, Consultation
and Coordination With Indian Tribal
Governments
G. Executive Order 13045, Protection of
Children From Environmental Health
Risks and Safety Risks
H. Executive Order 13211, Actions
Concerning Regulations That
Significantly Affect Energy Supply,
Distribution, or Use
I. National Technology Transfer and
Advancement Act
J. Executive Order 12898, Federal Actions
To Address Environmental Justice in
Minority Populations and Low-Income
Populations
I. Background
A. What is the statutory authority for
this action?
Section 112 of the Clean Air Act
(CAA) establishes a comprehensive
regulatory process to address emissions
of hazardous air pollutants (HAP) from
stationary sources. In accordance with
CAA section 112(c), EPA identifies
categories and subcategories of major
sources that emit one or more of the
HAP listed in CAA section 112(b). CAA
section 112(d) then calls for EPA to
promulgate national technology-based
emission standards for each listed
category or subcategory of sources. For
‘‘major sources’’ that emit or have the
potential to emit any single HAP at a
rate of 10 tons or more per year or any
combination of HAP at a rate of 25 tons
or more per year, these technologybased standards must reflect the
maximum reductions of HAP achievable
(after considering cost, energy
requirements, and non-air health and
environmental impacts) and are
commonly referred to as maximum
achievable control technology (MACT)
standards. The source categories listed
in Table 3 to this preamble are eight
source categories for which we have
promulgated MACT standards.
In what we refer to as the technology
review, CAA section 112(d)(6) then
requires EPA to review the CAA section
112(d) technology-based standards and
to revise them ‘‘as necessary, taking into
account developments in practices,
processes, and control technologies,’’ no
less frequently than every 8 years. If we
conclude a revision is necessary, we
must revise the standards.
The residual risk review is described
in section 112(f) of the CAA. CAA
section 112(f)(2) requires us to
promulgate standards for each category
or subcategory of CAA section 112(d)
70545
sources ‘‘if promulgation of such
standards is required in order to provide
an ample margin of safety to protect
public health * * * or to prevent,
taking into consideration costs, energy,
safety, and other relevant factors, an
adverse environmental effect.1 If
standards promulgated pursuant to CAA
section 112(d) and applicable to a
category or subcategory of source
emitting a pollutant (or pollutants)
classified as a known, probable or
possible human carcinogen do not
reduce lifetime excess cancer risks to
the individual most exposed to
emissions from a source in the category
or subcategory to less than 1-in-1
million, the Administrator shall
promulgate standards under this
subsection’’ for the source category (or
subcategory). EPA’s framework for
making ample margin of safety
determinations under CAA section
112(f)(2) is provided in the Benzene
NESHAP (54 FR 38044, September 14,
1989) and was codified by Congress in
CAA section 112(f)(2)(B).
B. Overview of the Four NESHAP
The eight industrial source categories
and four NESHAP that are the subject of
today’s proposal are listed in Table 3 to
this preamble. NESHAP limit and
control HAP that are known or
suspected to cause cancer or have other
serious human health or environmental
effects. The NESHAP for these eight
source categories generally required
implementation of technologies such as
steam strippers and incineration.
TABLE 3.—LIST OF NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS (NESHAP) AND INDUSTRIAL
SOURCE CATEGORIES AFFECTED BY TODAY’S PROPOSAL
Title of NESHAP
NESHAP for Group I Polymers and Resins1.
NESHAP for Epoxy Resins
Production and Non-nylon
Polyamides Production.
NESHAP for GMACT2 ...........
Source categories affected by
today’s proposal
Promulgated rule reference
Compliance
date
NESHAP as referred to in this
preamble
Polysulfide Rubber Production
Ethylene Propylene Rubber
Production.
Butyl Rubber Production.
Neoprene Production.
Epoxy Resins Production ......
Non-nylon Polyamides Production.
Acetal Resins Production ......
Hydrogen Fluoride Production.
61 FR 46905 (09/05/1996) ....
07/31/1997
Polymers and Resins I.
60 FR 12670 (03/08/1995) ....
03/03/1998
Polymers and Resins II.
64 FR 34853 (06/29/1999) ....
06/29/2002
GMACT.
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1 The Polymers and Resins I NESHAP regulates nine source categories. We are performing the residual risk and technology review for four of
them in this proposal. We will address the remaining five source categories in a separate risk and technology review rulemaking.
2 The source categories subject to the standards in the GMACT NESHAP are Acetal Resins Production and Hydrogen Fluoride Production.
1 Adverse environmental effect is defined in CAA
section 112(a)(7) as any significant and widespread
adverse effect, which may reasonably be
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anticipated, to wildlife, aquatic life, or other natural
resources, including adverse impacts on
populations of endangered or threatened species or
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significant degradation of environmental quality
over broad areas.
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1. Polymers and Resins I
The Polymers and Resins I NESHAP
applies to major sources and regulates
HAP emissions from nine source
categories. In today’s proposal, we
address four of the Polymer and Resins
I sources categories—Polysulfide Rubber
Production, Ethylene Propylene Rubber
Production, Butyl Rubber Production,
and Neoprene Production. HAP
emissions from these processes can be
released from storage tanks, process
vents, equipment leaks, and wastewater
operations.
These four source categories involve
the production of elastomers (i.e.,
synthetic rubber). An elastomer is a
synthetic polymeric material that can
stretch at least twice its original length
and then return rapidly to
approximately its original length when
released. Elastomers have long, flexible,
chainlike molecules that are able to
undergo rapid rotation (i.e., flex) as a
result of thermal agitation. Elastomers
are produced via a polymerization
process, in which monomers undergo
intermolecular chemical bonds to form
an insoluble, three-dimensional network
(i.e., a polymer). Generally, the
production of elastomers entails four
processes: (1) Raw material (i.e.,
solvent) storage and refining; (2)
polymer formation in a reactor (either
via the solution process, where
monomers are dissolved in an organic
solvent, or the emulsion process, where
monomers are dispersed in water using
a soap solution); (3) stripping and
material recovery; and (4) finishing (i.e.,
blending, aging, coagulation, washing,
and drying processes).
a. Polysulfide Rubber Production.
Polysulfide rubber is a synthetic rubber
produced by the reaction of sodium
sulfide and p-dichlorobenzene (1,4dichlorobenzene) at an elevated
temperature in a polar solvent.
Polysulfide rubber is resilient, resistant
to solvents, and has low temperature
flexibility, facilitating its use in seals,
caulks, automotive parts, rubber molds
for casting sculpture, and other
products.
During the development of the
NESHAP, we identified one polysulfide
rubber production facility as a major
source and subject to the Polymers and
Resins I NESHAP. This facility
consisted of raw material storage vessels
and was designated as a major source
because it was co-located with another
source. This polysulfide facility has
been dismantled and we are not aware
of any other facilities currently subject
to the NESHAP. (Even though no
polysulfide rubber facilities are
currently in operation, we completed a
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risk analysis based on the available
information on this facility as of 2002.)
The only HAP reported for this category
in the 2002 National Emissions
Inventory (NEI) was methylene
diphenyl diisocyanate.
b. Ethylene Propylene Rubber
Production. Ethylene propylene
elastomer is an elastomer prepared from
ethylene and propylene monomers.
Common uses for these elastomers
include radiator and heater hoses,
weather stripping, door and window
seals for cars, construction plastics
blending, wire and cable insulation and
jackets, and single-ply roofing
membranes.
We believe five ethylene propylene
rubber production facilities are
currently subject to the Polymers and
Resins I NESHAP. Hexane, which is the
HAP used as the solvent at three of the
plants, accounts for the majority of the
HAP emissions from these facilities
(over 95 percent of the total HAP
emissions by mass). These facilities also
reported relatively small emissions of
ethyl chloride, ethylene glycol, and
hydrogen chloride. Two facilities do not
use hexane in their processes. One
facility uses toluene instead of hexane
as a solvent and the other facility uses
a gas-phase process where methanol is
the only HAP emitted.
c. Butyl Rubber Production. The Butyl
Rubber Production source category
includes any facility that manufactures
copolymers of isobutylene and isoprene.
Butyl rubber is very impermeable to
common gases and resists oxidation. A
specialty group of butyl rubbers are
halogenated butyl rubbers, which are
produced commercially by dissolving
butyl rubber in hydrocarbon solvent and
contacting the solution with gaseous or
liquid elemental halogens such as
chlorine or bromine. Halogenated butyl
rubber resists aging to a higher degree
than the nonhalogenated type and is
more compatible with other types of
rubber. Uses for butyl rubber include
tires, tubes, and tire products;
automotive mechanical goods;
adhesives, caulks, and sealants; and
pharmaceutical uses.
We believe two butyl rubber
production facilities are currently
subject to the Polymers and Resins I
NESHAP. The primary HAP emitted
from butyl rubber production facilities
are methyl chloride (53 percent of the
total HAP emissions by mass) and
hydrochloric acid (34 percent). Hexane
is also emitted from the production of
halobutyl rubber, and it makes up
around 13 percent of the total HAP
emissions from the category.
d. Neoprene Production. Neoprene is
a polymer of chloroprene. Neoprene was
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Sfmt 4702
originally developed as an oil-resistant
substitute for natural rubber, and its
properties allow its use in a wide
variety of applications including
wetsuits, gaskets and seals, hoses and
tubing, plumbing fixtures, adhesives,
and other products.
We believe that one neoprene
production facility is currently subject
to the Polymers and Resins I NESHAP.
The primary HAP emitted by
production are chloroprene and toluene,
with chloroprene accounting for over 80
percent of the total emissions.
2. Polymers and Resins II
The Polymers and Resins II NESHAP
applies to major sources and regulates
HAP emissions from two source
categories—epoxy resins production
and non-nylon polyamides production.
HAP emissions from these source
categories can be released from storage
tanks, process vents, equipment leaks,
and wastewater operations.
a. Epoxy Resins Production. The
Epoxy Resins Production source
category generates HAP emissions from
the manufacture of basic liquid epoxy
resins used in the production of glues,
adhesives, plastic parts, and surface
coatings. This source category does not
include specialty or modified epoxy
resins.
We believe three epoxy resins
production facilities are currently
subject to the Polymers and Resins II
NESHAP. The HAP emitted in the
greatest quantity by mass from these
facilities are epichlorohydrin (referred
to by its synonym 1-chloro-2,3epoxypropane in the NEI and in the
accompanying emissions summary
table) and chlorobenzene. The total
emissions for these two HAP account for
approximately 87 percent of the total
HAP mass emitted by the facilities
regulated by the NESHAP.
Epichlorohydrin is emitted in the
greatest quantity and is reported as an
emission of all three facilities. Other
HAP such as phenol, xylenes, ethyl
benzene, propylene dichloride, allyl
chloride, 1,3-dichloropropene, glycol
ethers, methyl chloride, toluene,
acrolein, benzyl chloride, and ethyl
acrylate are emitted in smaller
quantities. All the other HAP are
reported as emissions by only one or
two of the facilities.
b. Non-nylon Polyamides Production.
The Non-nylon Polyamides Production
source category generates HAP
emissions from the manufacture of
epichlorohydrin cross-linked non-nylon
polyamides used primarily by the paper
industry as an additive to paper
products. Natural polymers, such as
those contained in paper products, have
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little cross-linking, which allows their
fibers to change position or separate
completely when in contact with water.
The addition of epichlorohydrin crosslinked non-nylon polyamides to these
polymers causes the formation of a
stable polymeric web among the natural
fibers. Because the polymeric web holds
the fibers in place even in the presence
of water, epichlorohydrin cross-linked
non-nylon polyamides are also referred
to as wet-strength resins.
We believe four non-nylon
polyamides production facilities are
currently subject to the Polymers and
Resins II NESHAP. Epichlorohydrin (64
percent) and hydrochloric acid (36
percent) are the only HAP emitted from
this category.
3. GMACT—Acetal Resins Production
The GMACT set national emission
standards for certain source categories
consisting of five or fewer facilities. The
basic purpose of the GMACT approach
was to use public and private sector
resources efficiently, and to promote
regulatory consistency and
predictability in the MACT standards
development.
Emission sources from acetal resin
production include storage vessels that
hold process feed materials, process
vents, process wastewater treatment
systems, and equipment leaks from
compressors, agitators, pressure relief
devices, sampling connection systems,
valves, connectors, and instrumentation
systems. The storage vessels associated
with acetal resin production are
primarily used for storage of solvents.
Back end process vent emissions occur
from reactor units, mixing vessels,
solvent recovery operations, and other
operations.
Acetal resins are characterized by the
use of formaldehyde in the
polymerization process to manufacture
homopolymers or copolymers of
alternating oxymethylene units. Acetal
resins, also known as
polyoxymethylenes, polyacetals, or
aldehyde resins, are a type of plastic
possessing relatively high strength and
rigidity without being brittle. They have
good frictional properties and are
resistant to moisture, heat, fatigue, and
solvents. Acetal resins are used as parts
in a variety of industrial applications,
e.g., gears, bearings, bushings, and
various other moving parts in
appliances and machines, and in a range
of consumer products, e.g., automotive
door handles, seat belt components,
plumbing fixtures, shaver cartridges,
zippers, and gas tank caps.
We believe three facilities are
currently subject to the acetal resins
production provisions in the GMACT.
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The primary HAP emitted by acetal
resin production are formaldehyde and
methanol, which make up 92 percent of
the total HAP emissions by mass.
4. GMACT—Hydrogen Fluoride
Production
The Hydrogen Fluoride Production
source category includes any facility
engaged in the production and recovery
of hydrogen fluoride by reacting
calcium fluoride with sulfuric acid.
Potential sources of HAP emissions at
hydrogen fluoride production facilities
include: Process vents on hydrogen
fluoride recovery and refining
equipment, storage vessels used to store
hydrogen fluoride, bulk loading of tank
trucks and tank rail cars, leaks from
hydrogen fluoride handling equipment,
and reaction kiln seal leaks. The only
HAP emitted from the processes in this
source category is hydrogen fluoride.
We believe two facilities are currently
subject to the hydrogen fluoride
production provisions in the GMACT.
C. How did we estimate risk posed by
the eight source categories?
To support the proposed decisions
presented in today’s notice, EPA
conducted an inhalation risk
assessment 2 that provided estimates of
maximum individual cancer risk, cancer
risk distribution within the exposed
populations, cancer incidence, hazard
indices for chronic exposures to HAP
with non-cancer health effects, and
hazard quotients (HQ) for acute
exposures to HAP with non-cancer
health effects. The risk assessment
consisted of six primary activities: (1)
Establishing the nature and magnitude
of emissions from the sources of
interest, (2) identifying the emissions
release characteristics (e.g., stack
parameters), (3) conducting dispersion
modeling to estimate the concentrations
of HAP in ambient air, (4) estimating
long-term and short-term inhalation
exposures to individuals residing within
50 km of the modeled sources, (5)
estimating individual and populationlevel risks using the exposure estimates
and quantitative dose-response
information, and (6) characterizing risk.
In general the risk assessment followed
a tiered, iterative approach, beginning
with a conservative screening-level
analysis and, where the screening
analysis indicated the potential for nonnegligible risks, following that with
more refined analyses. The following
2 For more information on the risk assessment
inputs and models, see ‘‘Residual Risk Assessment
for Eight Source Categories,’’ available in the
docket.
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sections summarize the results of these
efforts.
1. Emissions Data
For the Ethylene Propylene Rubber
Production, Butyl Rubber Production,
Neoprene Production, Epoxy Resins
Production, and Non-nylon Polyamides
Production source categories, we relied
primarily on emissions data and
emissions release characteristic data we
collected directly from industry. We
reviewed these data and consider them
to be the best emissions and emissions
release characteristic data available for
these five source categories.
For the remaining three source
categories, Polysulfide Rubber
Production, Acetal Resins Production,
and Hydrogen Fluoride Production, we
relied primarily on data in the 2002 NEI
Final Inventory,3 Version 1 (made
publicly available on February 26,
2006). For the Polysulfide Rubber
source category, the data in the 2002
NEI were used without further
investigation because the only facility in
the source category closed in 2002. For
the Acetal Resins and Hydrogen
Fluoride source categories, the 2002 NEI
data were supplemented with
information from industry and, for one
hydrogen fluoride facility, with
information from the State permitting
agency.
In response to an advanced notice of
proposed rulemaking 4 we published on
March 29, 2007, we received comments
on emissions data and emissions release
characteristics data for an acetal resins
production facility, two ethylene
propylene production facilities, and a
neoprene production facility. We will
include these comments in the docket
for this proposal (docket ID EPA–HQ–
OAR–2007–0211) and will evaluate
them with other comments we receive
in response to today’s proposal. The
data files for the eight source categories,
which are posted on the RTR webpage
and are described in Section III of this
preamble, will include the new data
provided by the commenters.
Emissions data and emissions release
characteristics data for these eight
source categories are documented in the
docket in ‘‘Documentation of Emissions
Data and Emissions Release
3 The National Emission Inventory (NEI) is a
database that contains information about sources
that emit criteria air pollutants and their precursors,
and HAP. The database includes estimates of
annual air pollutant emissions from point,
nonpoint, and mobile sources in the 50 States, the
District of Columbia, Puerto Rico, and the Virgin
Islands. EPA collects this information and releases
an updated version of the NEI database every 3
years.
4 Risk and Technology Review, Phase II, Group 2
at 72 FR 29287.
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Characteristics Data Used for the RTR
Group 1.’’ We specifically request
comment on whether the facilities listed
in our emissions data set accurately
reflect the universe of sources within
the source categories. For example, are
there records remaining in the data set
that are not part of the relevant source
category or any missing emissions data
that should be included for the relevant
source category?
2. Risk Assessment
Both long-term and short-term
inhalation exposure concentrations and
health risk from each of the eight source
categories addressed in today’s proposal
were estimated using the Human
Exposure Model (Community and
Sector HEM–3 version 1.1.0). The HEM–
3 model performs three main
operations: Dispersion modeling,
estimation of population exposure, and
estimation of human health risks. The
dispersion model used by HEM–3 is
AERMOD, which is one of EPA’s
preferred models for assessing pollutant
concentrations from industrial
facilities.5
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 are used for
dispersion calculations. This library
includes 1 year of hourly surface and
upper air observations for 130
meteorological stations, selected to
provide thorough coverage of the U.S.
and Puerto Rico. A second library of
U.S. Census Bureau census block
internal point locations and populations
provides the basis of human exposure
calculations (Census, 2000). In addition,
the census library includes the elevation
and controlling hill height for each
census block, which are also used in
dispersion calculations. A third library
of pollutant unit risk factors and other
health benchmarks is used to estimate
health risks. These risk factors and
health benchmarks are the latest values
recommended by EPA for HAP and
other toxic air pollutants, and are
discussed in more detail below. These
values are available at https://
www.epa.gov/ttn/atw/toxsource/
summary.html.
The risk assessment for chronic
exposures used the estimated annual
average ambient air concentration of
each HAP emitted by each source for
which we have emissions data in the
source category at each nearby census
5 Environmental Protection Agency. 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.
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block 6 centroid as a surrogate for the
chronic inhalation exposure
concentration for all the people who
reside in that census block. We
calculated the maximum individual risk
for each facility as the risk associated
with a lifetime (70-year) exposure to the
maximum concentration at the centroid
of an inhabited census block. Individual
cancer risks were calculated as the
lifetime exposure to the ambient
concentration of each HAP multiplied
by its Unit Risk Estimate (URE); total
cancer risks were the sum of the risks
of each carcinogenic HAP (including
known, probable, and possible
carcinogens) emitted by the modeled
source. Air concentrations of HAP from
sources other than the modeled source
were not estimated. Total cancer
incidence and the distribution of
individual cancer risks across the
population within 50 kilometers of any
source were also estimated as part of
these assessments by summing
individual risks. We are using 50
kilometers to be consistent with both
the analysis supporting the 1989
Benzene NESHAP (54 FR 38044) and
the limitations of Gaussian dispersion
modeling.
To assess risk of noncancer health
effects from chronic exposures, we
summed the HQ for each HAP that
affects a common target organ system to
obtain the hazard index (HI) for that
target organ system (or target organspecific hazard index, TOSHI), where
the HQ is the estimated exposure
divided by the chronic reference level
(e.g., the U.S. EPA Reference
Concentration (RfC) which is provided
through the Integrated Risk Information
System (IRIS)).
Health protective screening estimates
of acute exposures and risks were also
evaluated for each HAP at any location
off-site of each facility (i.e., not just the
census block centroids) assuming the
combination of a peak (hourly) emission
rate and hourly dispersion conditions
for the 1991 calendar year that would
tend to maximize exposure. In each
case, acute HQ were calculated using
best available short-term health indices.
We assumed that 10 times the average
annual hourly emission rate represented
a health protective emissions estimate to
evaluate acute exposures and risks for
these initial screens. The factor of 10 is
intended to cover routinely variable
emissions and startup, shutdown, and
malfunction emissions. We chose to use
a factor of 10 based on: (1) Engineering
judgment, and (2) a review of short-term
emissions data that compared hourly
6A
typical census block is comprised of
approximately 40 people or about 10 households.
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and annual emissions data for volatile
organic compounds for all facilities in a
heavily-industrialized 4-county area
(Harris, Galveston, Chambers, and
Brazoria Counties, TX) over an 11month time period in 2001.7 Most peak
emission events were less than twice the
annual average hourly emission rate and
the highest peak emission event was 8.5
times the annual average hourly
emission rate. We request comment on
the interpretation of these data and the
appropriateness of using a factor of 10
times the average annual hourly
emission rate in these acute exposure
screening assessments.
In cases where acute HQ values from
the screening step were less than or
equal to one, acute impacts were
deemed negligible and no further
analysis was performed. In the cases
where an acute HQ from the screening
step was greater than one, site-specific
data were sought to develop a more
refined estimate of the potential for
acute impacts of concern. These data
refinements included using a better
representation of the peak-to-mean
hourly emissions ratio (instead of using
the default factor of 10) and using the
site-specific facility layout to
distinguish facility property from an
area where the public could be exposed.
The screening analysis resulted in an
HQ less than or equal to one for all of
the source categories except Acetal
Resins Production and Hydrogen
Fluoride Production. The specific
refinements used for acetal resins
production and hydrogen fluoride
production are described in the results
section for the two source categories.
We engaged in a consultation with a
panel from the Science Advisory Board
(SAB) on the ‘‘Risk and Technology
Review (RTR) Assessment Plan’’ in
December of 2006. The results of this
consultation were transmitted to us in
June 2007 in a letter from the SAB
which also contained a summary listing
of the key messages from the panel. The
letter is available from the docket and
from https://www.epa.gov/sab/pdf/sab07-003_response_04-20-07.pdf. In
developing the risk assessments for the
eight source categories covered by this
proposal, we followed the RTR
Assessment Plan, addressing the key
recommendations from the panel, where
appropriate and relevant to these
assessments, but not the individual
recommendations from each panel
member. Our responses to each of the
SAB’s key recommendations are
summarized in an appendix to the
7 See https://www.tceq.state.tx.us/compliance/
field_ops/eer/ or docket to access the
source of these data.
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‘‘Residual Risk Assessment for Eight
Source Categories,’’ available in the
docket.
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3. Noncancer Inhalation Reference
Values
The most appropriate noncancer
inhalation reference values for chronic
durations in the Residual Risk Program
are in order of preference: (1) The RfC
which is provided through the IRIS; (2)
the Agency for Toxic Substances and
Disease Registry Chronic Minimal Risk
Levels; or (3) California Office of
Environment and Human Health
Assessment’s chronic Reference
Exposure Level (REL).
No such hierarchy was developed for
acute noncancer reference values.
Instead, we use acute inhalation values
from multiple sources because the
various assessments are based on
methods that are different enough to
render them not directly comparable,
nor does any one set of reference values
provide coverage across the majority of
chemicals. We looked to reference
values developed for other purposes,
such as Reference Exposure Levels
(REL), Acute Exposure Guideline Levels
(AEGLs), and Emergency Response
Planning Guideline (ERPGs).
The acute REL (https://
www.oehha.ca.gov/air/pdf/acuterel.pdf)
is defined as the concentration level at
or below which no adverse health
effects are anticipated for a specified
exposure duration. The REL
incorporates factors to address data
gaps, uncertainty, and to protect the
most sensitive individuals in the
population, and exceeding the REL does
not automatically indicate an adverse
health impact.
The AEGL–1 is ‘‘the airborne
concentration (expressed as ppm or
mg/m3) 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.’’ The AEGL values
are designed to be applicable to the
general population, including sensitive
subgroups; however, as stated in the
AEGL guidelines and the definitions, ‘‘it
is recognized that certain individuals,
subject to unique and idiosyncratic
responses, could experience effects at
concentrations below the corresponding
AEGL.’’ The National Research Council
states that ‘‘[t]he primary purpose of the
AEGL program and the NAC/AEGL
Committee is to develop guideline
levels for once-in-a-lifetime, short-term
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exposures to airborne concentrations of
acutely toxic, high-priority chemicals.’’ 8
The ERPG–1, developed specifically
for emergency response situations, is 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
perceiving a clearly defined,
objectionable odor. The ERPG
documentation also states that ‘‘in all
populations there are hypersensitive
individuals who will show adverse
responses at exposure concentrations far
below levels where most individuals
normally would respond.’’
The AEGL and ERPG values include
three levels of severity generally
referred to as mild, severe, and lethal. In
contrast, the REL represents an exposure
at which no adverse effects are
expected. For many chemicals (e.g.,
ethylene oxide and phosgene) the
available information does not allow
development of a mild effect AEGL or
ERPG. AEGL and ERPG values are
usually established at higher exposure
levels than Acute California REL
reference values. Exceedances of REL,
AEGL, or ERPG values in the context of
a residual risk assessment should be
interpreted on a case-by-case basis.
4. Consideration of Actual and
Allowable Emissions
Generally, the emissions values in our
data set represent actual emission
levels. We discussed the use of both
allowable and actual emissions in the
final Coke Oven Batteries residual risk
rule (70 FR 19998–19999, April 15,
2005) and in the proposed and final
Hazardous Organic NESHAP (HON)
residual risk rules (71 FR 34428, June
14, 2006, and 71 FR 76603, December
21, 2006, respectively). In those
previous actions, we noted that
modeling the allowable levels of
emissions (i.e., the highest emission
levels that could be emitted while still
complying with the MACT
requirements) is inherently reasonable
since they reflect the maximum level
sources could emit and still comply
with national emission standards. But
we also explained that it is reasonable
to consider actual emissions, where
such data are available, in both steps of
the Benzene NESHAP analysis. Doing so
avoids overestimating emissions and
their associated health risks and
8 See Standing Operating Procedures for
Developing Acute Exposure Guideline Levels for
Hazardous Chemicals (2001, National Academies
Press, Washington, DC, page 21, PURPOSE AND
OBJECTIVES OF THE AEGL PROGRAM AND THE
NAC/AEGL COMMITTEE; https://books.nap.edu/
openbook.php?record_id=10122&page=21).
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accounts for how sources typically
strive to perform better than required by
standards to allow for process
variability and to prevent exceeding
standards due to emissions increases on
individual days. Failure to consider
these data in risk assessments, we said,
would unrealistically inflate actual risk
levels. 71 FR at 76609.
For the eight source categories
addressed in this package, we do not
have information regarding allowable
emissions. This is similar to the
circumstance we faced in the HON. In
the preamble to the HON proposed rule,
we acknowledged that there is some
uncertainty regarding the difference
between actual and allowable
emissions. We also explained in the
HON preamble that it was not possible
to estimate allowable emissions for all
emission points from the available
information, but that for equipment
leaks, which represent the most
significant impact on cancer risk at
HON facilities, the actual and allowable
emissions are likely the same. We
further concluded that there was no
evidence of substantial overcontrol,
such that actual emissions would not be
a reasonable approximation of allowable
emissions, and that there was no
evidence that the sources subject to the
HON could make changes that would
result in a substantial increase of
emissions, and thus risk, while still
complying with the MACT. Therefore,
we concluded for the HON final rule
that basing the analysis on actual
emissions provided an acceptable
method for determining the remaining
risks to public health and the
environment after application of the
MACT standards.
The production processes for
polymers and resins use the same
process equipment and air pollution
control equipment as HON processes.
Thus, we believe we can draw the same
conclusions for polysulfide rubber
production, ethylene propylene rubber
production, butyl rubber production,
neoprene rubber production, epoxy
resins production, non-nylon
polyamides production, and acetal
resins as we did for the HON—that
estimating risk using actual emissions
will reasonably reflect the risk after
application of the relevant MACT
standards.
For the Hydrogen Fluoride Production
source category, we expect actual and
allowable emissions to be similar, if not
the same. Hydrogen fluoride facilities
employed stringent controls prior to the
development of the MACT standards
(we based the MACT standards on these
pre-MACT controls) and we have no
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reason to believe control performance
will decline.
We believe the differences between
actual and allowable emissions are
likely insignificant for these eight
source categories and that using the
actual emission levels results in a
reasonable approximation of the
allowable emissions. Therefore, we
conclude that the risk assessment
results using actual emissions closely
approximate those for an assessment
using allowable emissions and that the
difference would not be likely to
substantially affect the estimated risk
associated with exposure to HAP
emitted by any of the eight source
categories. Nevertheless, if commenters
have data that demonstrate that
allowable emissions could be higher or
lower than actual emissions for these
eight source categories we request the
submission of this data.
5. Adverse Environmental Effects
Assessment
None of the eight source categories
emit persistent or bioaccumulative HAP;
therefore, EPA’s assessment of
environmental effects evaluated only
non-persistent and non-bioaccumulative
HAP.9 For animal populations, the
potential for significant direct adverse
environmental effects due to nonpersistent and non-bioaccumulative
HAP was evaluated implicitly by
checking for exceedances of any human
health inhalation dose-response limit
values near the assessed facilities. 10
Because these values generally reflect
the inclusion of uncertainty factors 11
(often 100 or 1,000), the human
threshold values are generally believed
to be significantly lower than any levels
which have been shown to cause an
adverse effect in an exposed animal.
Therefore, if the maximum inhalation
hazard in an ecosystem is below the
level of concern for humans, we have
concluded that, in general,
environmental receptors should be at
little risk of adverse effects due to
airborne exposures.
One possible exception is pollutants
that may directly impact various species
of vegetation. For the seven polymers
and resins production source categories
affected by today’s proposal, we have no
scientific data, informal observations or
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9 Persistent
and bioaccumulative HAP are those
which persist in the environment and which also
may bioaccumulate or biomagnify in food chains.
10 While environmental effects thresholds are
often available for HAP in water and soil, very few
are available for direct airborne exposures.
11 The uncertainty factors account for various data
methodological uncertainties, for example, most
inhalation dose-response limit values are derived
from studies of laboratory animals.
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other information that would indicate
any concern for adverse environmental
effects of HAP on vegetation at the
expected air concentrations.
For the two facilities in the Hydrogen
Fluoride Production source category
(both of which emit hydrogen fluoride),
we have some general information on
the possible effects of hydrogen fluoride
on vegetation at ambient concentrations
well below the California chronic REL
value of 14 microgram per cubic meter
(µg/m3). In separate and unrelated
studies, air concentrations of hydrogen
fluoride greater than about 1 µg/m3 have
been shown to adversely affect specific
sensitive plant species. 12 We note that
responses to hydrogen fluoride are
highly variable among plant species and
responses may be influenced by coexposures to other air pollutants. In this
particular case, the maximum chronic
ambient concentration estimated in the
vicinity of the hydrogen fluoride
production facilities was about 1.5 µg/
m3, meaning that concentrations of
hydrogen fluoride in all areas other than
the maximum point are lower than 1.5
µg/m3, and perhaps substantially lower
as the distance from the point of release
increases. Because the spatiallyaveraged hydrogen fluoride
concentration within several kilometers
of each facility is likely well below 1 µg/
m3, we are led to the conclusion that
any significant and widespread adverse
environmental effects on plants due to
hydrogen fluoride emissions are
unlikely. Further, we have no
information suggesting that there are
currently observed adverse impacts of
hydrogen fluoride emissions on plants
surrounding the two facilities.
6. Uncertainties in Risk Assessments
Uncertainty and the potential for bias
are inherent in all risk assessments,
including those performed for the eight
source categories affected by today’s
proposal. We reduced some of these
uncertainties by developing a new
emissions data set, the RTR database,
that is based on the NEI, but that
includes more accurate replacement or
supplemental data for the specific
facilities in these eight source
categories.
Although uncertainty exists, we
believe the risk assessments performed
for the eight source categories most
likely overestimate the potential for
12 1 µg/m3 was the lowest concentration for which
adverse effects were observed in the most sensitive
flora for which data exists. We note that the studies
were limited to certain species and 1 µg/m3 cannot
be interpreted as an appropriate or definitive
concentration level for all plant species. (See ‘‘List
of References for Effects of Hydrogen Fluoride on
Vegetation’’ in docket.)
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risks due to the conservative (i.e.,
health-protective) assessment approach.
Because these health protective risk
assessments indicate little, if any,
potential for significant risk, we believe
they support our proposed decision not
to issue residual risk standards for these
eight source categories. A brief
discussion of the uncertainties in the
emissions data set, dispersion modeling,
inhalation exposure estimates, and
dose-response relationships is presented
in this section of the preamble. A fuller
discussion of these uncertainties is
discussed in both the ‘‘Residual Risk
Assessment for Eight Source Categories’’
(July 2007) and the ‘‘Risk and
Technology Review (RTR) Assessment
Plan’’ (November 2006), both of which
are available in the docket.
a. Uncertainties in the RTR Emissions
Database. Although the development of
the RTR database involved quality
assurance/quality control processes, the
accuracy of emissions values will vary
depending on the source of the data
present, incomplete or missing data,
errors in estimating emissions values,
and other factors. The emission values
considered in this analysis are annual
totals that do not reflect actual
fluctuations during the course of a year
(2002) or variations from year to year.
These annual emissions estimates do
not consider operations such as startup/
shutdown and malfunctions. The
estimates of health protective short-term
emission rates for the screening
assessment were based on a healthprotective default assumption
applicable to these source categories (10
times the annual rate). More refined
estimates were used for source
categories where the screening estimates
did not ‘‘screen out’’ all sources and
more specific information was available.
Facilities in some of the seven
polymers and resins source categories
emit chlorinated compounds and use
incineration devices, creating the
possibility for the formation of
polychlorinated dioxins. However, we
have no test reports or measurements,
conducted by manufacturers or anyone
else, indicating the presence of dioxins
in the emissions from any of these
source categories and EPA’s dioxins
inventory 13 does not specifically link
13 An Inventory of Sources and Environmental
Releases of Dioxin-Like Compounds in the United
States for the Years 1987, 1995, and 2000. (EPA/
600/P–03/002f, Final Report, November 2006). The
dioxins inventory (https://cfpub.epa.gov/ncea/cfm/
recordisplay.cfm?deid=159286) classifies ‘‘rubber
manufacturing’’ as an unquantifiable dioxins
emission source. A source was defined as
unquantifiable if dioxins releases were possible, but
the data were inadequate to support even
rudimentary calculations of emissions.
Furthermore, the process could be very different
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dioxins emissions to any of these source
categories. Furthermore, in our
judgment, it is improbable that dioxins
are emitted in measurable amounts from
the seven polymers and resins source
categories, especially given the low
quantity of particulate matter present.
Therefore, we did not consider dioxins
in our assessment of the seven polymers
and resins production source categories.
Because no chlorinated compounds are
emitted from the hydrogen fluoride
production source category, we believe
there is no possibility for dioxins to be
emitted and we did not consider dioxins
in our assessment of the source
category.
Overall we believe that the emissions
data considered in this assessment are
the most accurate available
representation of the eight source
categories for the stated purpose.
Nevertheless, we request comment on
our emissions data set in general, and
specifically on our approach to shortterm emissions estimates and on the
potential for dioxins emissions from the
facilities in the seven polymers and
resins production source categories
affected by today’s proposal.
b. Uncertainties in Dispersion
Modeling. While the analysis employed
EPA’s suggested regulatory dispersion
model, AERMOD, there is uncertainty in
ambient concentration estimates
associated with EPA’s choice and
application of the model. Where
possible, model options (e.g., rural/
urban, plume depletion, chemistry)
were selected as to provide an
overestimate of ambient air
concentrations. However, because of
practicality and data limitation reasons,
some factors (e.g., meteorology, building
downwash) have the potential in some
situations to overestimate or
underestimate ambient impacts. For
example, meteorological data were
taken from a single year (1991), and
facility locations can be a significant
distance from the site where these data
were taken. Despite these uncertainties,
we believe that at off-site locations and
census block centroids, the approach
considered in the dispersion modeling
analysis should generally yield
overestimates of ambient
concentrations.
c. Uncertainties in Inhalation
Exposure. The effects of human mobility
on exposures were not included in the
assessment. Specifically, short-term
mobility and long-term mobility14
from the polymers and resins processes of concern
in this proposal.
14 Short-term mobility is movement from one
microenvironment to another over the course of
hours or days. Long-term mobility is movement
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between census blocks in the modeling
domain was not considered. As a result,
this simplification will likely bias the
assessment toward overestimating the
highest exposures. In addition, the
assessment predicted the chronic
exposures at the centroid of each
populated census block as surrogates for
the exposure concentrations for all
people living in that block. (On average
census blocks are populated by
approximately 40 people.) Using the
census block centroid to predict chronic
exposures tends to overpredict
exposures for people in the census block
who live further from the facility and
underpredict exposures for people in
the census block who live closer to the
facility. Thus, in general, using the
census block centroid to predict chronic
exposures leads to a potential
understatement or overstatement of
maximum impact and an unbiased
estimate of average risk and incidence.
The assessments evaluate the cancer
inhalation risks associated with
pollutant exposures over a 70-year
period, the assumed lifetime of
individuals. In reality, both the length of
time that modeled emissions sources at
facilities actually operate (i.e., more or
less than 70 years), and the domestic
growth or decline of the modeled
industry (i.e., the increase or decrease in
the number or size of U.S. facilities),
will influence the risks posed by a given
source category. Depending on the
characteristics of the industry, these
factors may result in an overestimate (or
possibly an underestimate in the
extreme case where a facility maintains
or increases its emission levels beyond
70 years and residents live beyond 70
years at the same location) both in
individual risk levels and in the total
estimated number of cancer cases.
Annual cancer incidence estimates from
exposures to emissions from these
sources would not be affected by
uncertainty in the length of time
emissions sources operate.
The exposure estimates used in these
analyses assume chronic exposures to
ambient levels of pollutants. Because
most people spend the majority of their
time indoors, actual exposures may not
be the same, depending on
characteristics of the pollutants
modeled. For many HAP, indoor levels
are roughly equivalent to ambient
levels, but for very reactive pollutants or
larger particles, these levels are
typically lower. This factor has the
potential to result in an overstatement of
25 to 30 percent of exposures.15
In addition to the uncertainties
highlighted above, there are several
factors specific to the acute exposure
assessment that need to be highlighted.
The accuracy of an acute inhalation
exposure assessment depends on the
joint occurrence of independent factors
that may vary greatly, such as hourly
emissions rates, meteorology, and
human activity patterns. In this
assessment, we assume that individuals
remain for one hour at the point of
maximum ambient concentration as
determined by the co-occurrence of
peak emissions and worst-case
meteorological conditions. These
assumptions would tend to overestimate
actual exposures since it is unlikely that
a person would be located at the point
of maximum exposure during the time
of worst-case impact.
d. Uncertainties in Dose-Response
Relationships. These assessments use
toxicological dose-response values
typically extrapolated from high-dose
animal exposure or occupational
exposures, to estimate risk. Consistent
with EPA guidance, RfCs are developed
by using order-of-magnitude factors to
account for uncertainties in developing
values protective of sensitive
subpopulations. Most of the URE in this
assessment were developed using linear
low-dose extrapolation. Risks could be
overestimated if the true dose-response
relationship (which is usually
unknown) is sublinear and
underestimated when the dose-response
curve is actually superlinear. Impacts
have been extrapolated from shortduration, high-dose animal or
occupational exposures to longer
durations and lower doses, using
uncertain interspecies scaling methods.
In general, EPA considers these URE’s to
be upper bound estimates based on the
method of extrapolation, meaning they
represent a plausible upper limit to the
true value. (Note that this is usually not
a true statistical confidence limit.) The
true risk is therefore likely to be less,
could be as low as zero, but also could
be greater. As previously noted, benzene
cancer risks were estimated from the
reported URE range, which is
considered to be based on maximum
likelihood exposure and risk estimates.
Some HAP have no dose-response
values for cancer, chronic non-cancer,
and/or acute effects. Therefore, an
understatement of risk for certain HAP
at environmental exposure levels is
possible if there are no health effects
reference values available on which to
from one residence to another over the course of a
lifetime.
15 National-Scale Air Toxics Assessment for 1996.
(EPA 453/R–01–003; January 2001; page 85.)
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base an assessment of health risk.
Additionally, some chronic doseresponse values used in the assessments
for these 8 source categories are
currently under EPA IRIS review (e.g.,
formaldehyde and methanol) and
revised assessments may determine that
these HAP are more or less potent than
currently thought. We will consider the
outcome of new assessments and
reevaluate residual risk if application of
new dose-response values indicates the
potential for unacceptable risks to
human health and/or the environment.
e. Uncertainties in the Adverse
Environmental Effects Assessment. As
previously discussed, we generally
believe that when exposure levels are
not anticipated to adversely affect
human health, they also are not
anticipated to adversely affect the
environment. However, we recognize
that this may not be the case for all
HAP. Hydrogen fluoride in the air has
the potential to adversely affect plant
effects as defined in CAA section
112(a)(7).16
tissues, having been associated with
necrosis (lesions) in plants and reduced
plant growth and productivity.
Determining the effects of hydrogen
fluoride on vegetation is complicated by
the high degree of variability among
plant species in the extent of uptake and
response to atmospheric hydrogen
fluoride, and by co-exposure to other
atmospheric pollutants, such as sulfur
dioxide, that influences the impacts of
hydrogen fluoride. (For references
concerning the effects of hydrogen
fluoride on plants, see docket item ‘‘List
of References for Effects of Hydrogen
Fluoride on Vegetation’’.)
EPA requests comment on this issue,
including: Submissions of any data that
should be considered; observations, if
any, of impacts on vegetation near the
two facilities in the hydrogen fluoride
production source category; and
suggestions of how EPA should assess
the potential for adverse environmental
D. What are the conclusions of the risk
review?
The human health risks estimated for
the eight source categories are
summarized in this section of the
preamble. Details of the assessment are
located in the docket, especially see
‘‘How to Reproduce Modeling of Group
1 Source Categories’’ (May 2007). We
believe that our assessment covers all
potential health risks associated with
HAP emissions from the eight source
categories affected by today’s proposal.
We further believe that the reported
emissions are consistent with the
expected constituents and amounts for
these source categories. The sections
below provide more detailed
discussions about the human health risk
assessment results for each of the eight
source categories.
TABLE 4.—SUMMARY OF ESTIMATED INHALATION RISKS FOR THE EIGHT SOURCE CATEGORIES
Number of facilities1
Maximum individual
cancer risk (in a million) 2 and HAP of most
concern
Estimated annual cancer incidence and HAP
of most concern
Max. HI 3 and HAP of
most concern
Polysulfide Rubber Production.
Ethylene Propylene
Rubber Production.
Butyl Rubber Production
1
0 6 ................................
0 6 ................................
<0.01 (MDI 5) ...............
0.0004AEGL– 1 (MDI4).
5
0 6 ................................
0 6 ................................
0.5 (hexane) ................
0.3REL (toluene).
2
0 6 ................................
0 6 ................................
0.2 (methyl chloride) ...
Neoprene Production ....
Epoxy Resins Production.
Non-nylon Polyamides
Production.
Acetal Resins Production.
Hydrogen Fluoride Production.
1
3
0 6 ................................
0.1 (epichlorohydrin) ...
0.8 (chloroprene) .........
0.1 (epichlorohydrin) ...
4
0.4 (epichlorohydrin) ...
3
0.3 (allyl chloride) ........
0 6 ................................
0.00002
(epichlorohydrin).
0.00003
(epichlorohydrin).
0.00004 (allyl chloride)
0.2 (chlorine) ...............
0.1AEGL–2(methyl chloride 7).
0.4REL (toluene).
0.6REL
(epichlorohydrin).
0.2REL
(epichlorohydrin).
1.7REL (formaldehyde).
2
0 6 ................................
0 6 ................................
<0.01 (hydrofluoric
acid).
0.3REL (hydrofluoric
acid).
Source category
0.3 (epichlorohydrin) ...
Maximum off-site acute
HQ and HAP of most 4
concern
1 Number
of facilities believed to be in the source category and used in the risk analysis.
individual excess lifetime cancer risk.
3 Maximum hazard index (HI) is maximum respiratory HI for all except two source categories. Maximum HI for butyl rubber production is based
on neurological effects. Maximum HI for hydrogen fluoride production is based on skeletal effects.
4 The maximum estimated acute exposure concentration was divided by available short-term threshold values to develop an array of hazard
quotient (HQ) values. These include RELs and AEGL–1 and AEGL–2 values. The acute REL is an exposure that is not likely to cause adverse
effects in a human population, including sensitive subgroups, exposed to that concentration for one hour on an intermittent basis. AEGL–1 is the
airborne concentration (expressed as ppm or mg/m3) 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. AEGL–2 is the airborne concentration (expressed as ppm or mg/m3) 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.
5 MDI is methylene diphenyl diisocyanate.
6 No HAP which are known, probable, or possible human carcinogens.
7 For methyl chloride, REL and AEGL–1 were not available.
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2 Maximum
As shown in Table 4, we estimate that
the residual risk remaining from HAP
emissions from these eight source
categories affected by today’s proposal
do not pose cancer risks equal to or
greater than 1-in-1 million to the
individual most exposed, do not result
in meaningful rates of cancer incidence,
and do not result in a concern regarding
either chronic or acute noncancer health
effects for the individual most exposed.
No chronic inhalation human health
thresholds were exceeded at ecological
receptors for any of the eight source
16 CAA section 112(a)(7) defines ‘‘adverse
environmental effect’’ as meaning ‘‘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.
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categories; therefore, we believe there is
low potential for adverse environmental
effects due to direct airborne exposures.
We also believe that there is no
potential for an adverse effect on
threatened or endangered species or on
their critical habitat within the meaning
of 50 CFR 402.13(a) because our
screening analyses indicate no potential
for any adverse ecological impacts.
Thus, we conclude that a consultation
with the Fish and Wildlife Service is not
necessary for any of the eight source
categories.
Human health multipathway risks
were determined not to be a concern for
the eight source categories addressed in
today’s proposal due to the absence of
persistent and bioaccumulative (PB) 17
HAP emissions at all of these sources.
The lack of PB HAP emissions also
provides assurance that there will be no
potential for adverse ecological effects
due to indirect ecological exposures
(i.e., exposures resulting from the
deposition of PB HAP from the
atmosphere).
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1. Polymers and Resins I—Polysulfide
Rubber Production
The only HAP emitted by the
Polysulfide Rubber Production source
category in 2002 was 4,4’-methylene
diphenyl diisocyanate (MDI), whose
carcinogenic potential was evaluated in
EPA’s IRIS in 1998, and characterized as
‘‘cannot be determined, but for which
there is suggestive evidence that raises
concern for carcinogenic effects.’’
The maximum chronic noncancer
TOSHI associated with emissions from
polysulfide rubber production is less
than 0.01, indicating that chronic
noncancer risks are negligible. Further,
our analysis, based on available
information, indicates this source
category poses no potential for adverse
environmental impacts. Combining
these results with the lack of
information on potential cancer risks
and the additional fact that no sources
in this category are currently in
operation, we conclude that there is no
reason to modify the existing standard.
2. Polymers and Resins I—Ethylene
Propylene Rubber Production
Because none of the HAP emitted are
known, probable, or possible human
carcinogens, we currently believe there
are no cancer risks associated with
exposures to the HAP emissions from
this source category. The maximum
17 Persistent
and bioaccumulative (PB) HAP are
the list of 14 HAP that have the ability to persist
in the environment for long periods of time and
may also have the ability to build up in the food
chain to levels that are harmful to human health
and the environment.
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chronic noncancer TOSHI value
associated with emissions from ethylene
propylene rubber production is 0.5. No
adverse noncancer health effects
associated with the modeled acute or
chronic inhalation exposures are
expected from the Ethylene Propylene
Rubber Production source category. Our
analysis, based on available
information, indicates this source
category poses no potential for adverse
environmental impacts.
3. Polymers and Resins I—Butyl Rubber
Production
Because none of the HAP emitted are
known, probable, or possible human
carcinogens, we currently believe there
are no cancer risks associated with
exposures to the HAP emissions from
this source category. The maximum
chronic noncancer TOSHI value
associated with emissions from butyl
rubber production is 0.2. We saw no
exceedances of any available acute
thresholds. Our analysis, based on
available information, indicates this
source category poses no potential for
adverse environmental impacts.
A source of uncertainty unique to this
source category is the lack of certain
acute dose-response values (REL and
AEGL) for methyl chloride. Since the
only acute dose-response value
available is for methyl chloride is the
ERPG2 18 value which doesn’t account
for possible mild transient effects, there
is some uncertainty regarding the
conclusion that there are no possible
acute impacts of concern.
4. Polymers and Resins I—Neoprene
Production
Because none of the HAP emitted are
known, probable, or possible human
carcinogens, we currently believe there
are no cancer risks associated with
exposures to the HAP emissions from
this source category. The maximum
chronic noncancer TOSHI value
associated with emissions from
neoprene production is 0.8. There are
no expected adverse noncancer health
effects associated with the modeled
acute or chronic inhalation exposures
from the Neoprene Production source
category. Our analysis, based on
available information, indicates this
source category poses no potential for
adverse environmental impacts.
18 ERPG–2 is the maximum airborne
concentration below which it is believed that nearly
all individuals could be exposed for up to 1 hour
without experiencing or developing irreversible or
other serious health effects or symptoms which
could impair an individual’s ability to take
protective action.
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5. Polymers and Resins II—Epoxy
Resins Production
All lifetime cancer risks associated
with emissions from the three epoxy
resins production facilities are
estimated to be less than 1-in-1 million.
The highest maximum lifetime
individual cancer risk was estimated at
0.1-in-1 million. The total estimated
cancer incidence from these facilities is
0.00002 excess cancer cases per year.
The maximum chronic noncancer
TOSHI value associated with emissions
from epoxy resins production is 0.1. We
saw no exceedances of any available
acute thresholds. Our analysis, based on
available information, indicates this
source category poses no potential for
adverse environmental impacts.
6. Polymers and Resins II—Non-Nylon
Polyamides Production
All lifetime cancer risks associated
with emissions from the four non-nylon
polyamides production facilities are
estimated to be less than 1-in-1 million.
The highest maximum lifetime
individual cancer risk was estimated at
0.4-in-1 million. The total estimated
cancer incidence from these facilities is
0.00003 excess cancer cases per year.
The maximum chronic noncancer
TOSHI value associated with emissions
from non-nylon polyamides production
is 0.3. There are no expected adverse
noncancer health effects associated with
the modeled acute or chronic exposures
from the neoprene production source
category. Our analysis, based on
available information, indicates this
source category poses no potential for
adverse environmental impacts.
7. GMACT—Acetal Resins Production
All lifetime cancer risks associated
with emissions from the three acetal
resins production facilities are
estimated to be less than 1-in-1 million.
The highest maximum lifetime
individual cancer risk was estimated at
0.3-in-1 million. The total estimated
cancer incidence from these facilities is
0.00004 excess cancer cases per year.
The maximum chronic noncancer
TOSHI value associated with emissions
from acetal resins production is 0.2. Our
analysis, based on available
information, indicates this source
category poses no potential for adverse
environmental impacts.
The initial screening assessment for
acute impacts suggested that short-term
formaldehyde concentrations at the
three modeled facilities could exceed
acute thresholds if worst-case
meteorological conditions are present
and if maximum hourly emissions of
formaldehyde exceed the average hourly
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emission rate by a factor of 10. One of
the facilities showed potential
exceedances of the REL only, and two
facilities showed potential exceedances
of both the REL and the AEGL–1.
Therefore, we performed further sitespecific analysis and mapped the
screening results as a series of
concentration isopleths overlaid against
the aerial photograph of the facility in
question. The results of this exercise for
the first facility were that the isopleths
that exceeded the REL did not extend
off the facility site. Therefore, acute
exposures to HAP emitted by this
facility are not expected to pose any
public health concerns. We further
refined the assessments using better
site-specific data for the other two
facilities. Discussions with a plant
engineer for one facility revealed that
the acetal resins processes operate
continuously and that a reasonable
worst-case emissions multiplier would
be 1.5 instead of our default multiplier
of 10. We performed more refined
modeling (AERMOD) for these two
facilities using the emissions multiplier
of 1.5. The results for the second facility
indicated no potential for exceeding the
AEGL–1 and showed that the potential
for exceedances of the REL did not
extend off-site, except for a small
extension over a river to the north of the
facility. The maximum off-site REL HQ
corresponding to these locations is 1.7
(HQ = 0.14 using the AEGL–1). The
analysis showed that meteorological
conditions resulting in exceedances of
the REL may occur up to 2 hours per
year along the river. We believe the
potential for adverse acute health effects
surrounding this facility is low. The
results for the third facility showed
potential for exceeding the REL in an
area immediately adjacent to the facility
along a roadway. The maximum off-site
HQ for this facility is 1.6 for the REL
(HQ = 0.13 using the AEGL–1). The
analysis showed that meteorological
conditions resulting in exceedances of
the REL may occur up to 46 hours per
year along the roadway. Additionally,
the third facility reports that current
actual emissions for this facility are
significantly less than those used for
this assessment because one of the
higher emission sources listed for this
facility in the 2002 NEI data has been
shut down. Based on this new
information, we believe that the actual
projected maximum off-site HQ for this
facility is less than 1.0. We request
interpretation and comment on this as
well as any additional data regarding
the potential acute impacts of these
facilities.
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A source of uncertainty that is unique
to this source category is associated
with annual emissions of HAP and the
relationship between annual emissions
and maximum hourly emissions. One
facility reports emissions of benzene
and allyl chloride, which are two
relatively toxic HAP not expected to be
emitted from this source category. Since
the risk assessment shows allyl chloride
to be the cancer risk driver for the
source category, this indicates a
potential overestimate of the cancer
risks
8. GMACT—Hydrogen Fluoride
Production
Because hydrogen fluoride, the only
HAP emitted from the source category,
is not a known, probable, or possible
human carcinogen, we currently believe
there are no cancer risks associated with
exposures to the HAP emissions from
this source category. The maximum
chronic noncancer TOSHI value
associated with emissions from
hydrogen fluoride production is less
than 0.01.
The initial screening assessment for
acute impacts suggests that short-term
hydrofluoric acid concentrations at the
two modeled facilities could exceed
acute thresholds if worst-case
meteorological conditions are present
and if maximum hourly emissions of
hydrofluoric acid exceed the average
hourly emission rate by a factor of 10.
Since one of the facilities showed
potential exceedances of the REL only,
and one facility showed potential
exceedances of both the REL and the
AEGL–1, we performed additional site
specific assessments. We contacted the
permitting agency and a process
engineer at one of the facilities to gather
additional source specific information.
Based on discussions with the
permitting agency and the process
engineer, we determined that these
facilities operate continuously and that
the peak hourly emissions are not
expected to exceed twice the hourly
average. By adjusting the short-term
emission rate to more accurately
represent the true facility operating
conditions (from 10 to 2), no offsite
impacts above the REL were predicted
from the first facility. For the second
facility that exceeded both the REL and
AEGL–1, we remodeled using the
AERMOD model to more accurately
predict the worst case acute impacts. By
adjusting the short-term emission rate to
more accurately represent facility
operating conditions (from 10 to 2),
exceedances of the REL and AEGL–1
were predicted to occur within the
facility property boundary, but not
offsite.
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A source of uncertainty unique to this
source category involves the adequacy
of our screening for potential adverse
environmental effects for the pollutant
hydrogen fluoride, as discussed in
section I.C.6.e of this preamble. Indeed,
there is a significant lack of scientific
understanding and assessment
methodologies for such potential
adverse environmental effects. However,
we believe acute and chronic noncancer
assessment results (maximum chronic
TOSHI less than 0.01 and maximum
acute HQ of 0.3 for REL and 0.09 for
AGEL–1) support our conclusion that no
adverse environmental impacts are
expected for this source category.
E. What are the conclusions of the
technology review?
For seven of the source categories
affected by today’s proposal (all except
the Hydrogen Fluoride Production
source category), we relied on the
technology review conducted for the
HON, which did not identify any
significant developments in practices,
processes, or control technologies since
promulgation of the original HON
standards in 1994.19 These seven source
categories are similar to those under the
HON because they use the same kinds
of process and pollution control
equipment and are subject to similar
control requirements.20 For the seven
HON-like source categories affected by
today’s proposal, we conclude that
imposing additional controls under any
control option would achieve, at best,
minimal emission and risk reductions.
Furthermore, elimination of all HAP, if
it were possible, from all seven of these
source categories combined would
reduce estimated cancer incidence by
less than 0.0002 cases per year. For HAP
with available dose-response values, the
maximum HI for these facilities are all
below one and the cancer risks are all
below 1-in-1 million.
Elimination of all HAP 21 emissions
from the Hydrogen Fluoride source
category, if it were possible, would
reduce HAP emissions by 8 tons per
year and would not affect cancer
incidence, which is 0 (hydrogen
fluoride is not a known, probable, or
possible human carcinogens). The
noncancer risk is low (the maximum HI
is less than 0.01 with the current level
of emissions achieved by the GMACT)
19 Discussed in the proposed and final HON
residual risk preambles (71 FR 34428, June 14,
2006, and 71 FR 76603, December 21, 2006,
respectively).
20 Process equipment, pollution control
equipment, and control requirements are
summarized in the proposal BID.
21 Hydrogen fluoride is the only HAP emitted
from the Hydrogen Fluoride source category.
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and further emissions reductions would
provide insignificant, if any, health
benefits. In addition, all hydrogen
fluoride emissions are from control
device vents equipped with control
devices that achieve 99 percent
reductions. Improvements in hydrogen
fluoride controls are not feasible.
We conclude that the existing MACT
standards effectively address HAP
emissions for all eight source categories:
Cancer risks and incidence to humans,
chronic and acute exposure noncancer
risks to humans, and adverse
environmental effects from these
facilities are insignificant based on
available health benchmarks, and no
advancements in practices, processes, or
control technology that make additional
controls cost-effective are known.
II. Proposed Action
Section 112(f) of the CAA requires
that EPA promulgate standards for a
category if promulgation of such
standards is required to provide an
ample margin of safety to protect public
health or to prevent, taking into
consideration costs, energy, safety, and
other relevant factors, an adverse
environmental effect. The approach we
use is that set forth in the preamble to
the Benzene NESHAP. First we
exclusively evaluate health risk
measures and information in
determining whether risks are
acceptable. Second, we may consider
costs and other factors in deciding
whether further emission reductions are
necessary to protect public health with
an ample margin of safety. The Benzene
NESHAP preamble explained that in
protecting public health with an ample
margin of safety under CAA section 112,
EPA strives to provide maximum
feasible protection against risks to
health from HAP by protecting the
greatest number of persons possible to
an individual lifetime risk level no
higher than approximately 1-in-1
million.
EPA is not required to promulgate
standards for a source category under
section 112(f) if public health is
protected with an ample margin of
safety and adverse environmental effects
are prevented. For the eight source
categories that are the subject of today’s
notice, we have concluded (based on the
results of risk assessments) that the
existing MACT standards protect public
health with an ample margin of safety
and prevent an adverse environmental
effect. In making this conclusion, we
determined that the source categories
addressed in today’s proposal that emit
one or more HAP which are known or
potential carcinogens pose cancer risks
less than or equal to 1-in-1 million to
the individual most exposed. In
addition, we also determined that
emissions from these source categories
result in chronic noncancer target organspecific HI less than or equal to 1 for the
individual most exposed, are unlikely to
result in health effects under acute
scenarios and are not anticipated to
pose any significant and widespread
adverse environmental effects. In
reaching this conclusion, we did not
consider costs.
Furthermore, as explained in section
I.E. of this preamble, there have been no
significant developments in practices,
processes, or control technologies since
promulgation of the MACT standards.
Because there have been no such
significant developments and because
public health is protected with an ample
margin of safety, we conclude that no
further revisions to the standards
affected by today’s proposal are needed
under section 112(d)(6) of the CAA.
Therefore, we propose no revisions to
the standards for the eight source
categories: Butyl Rubber Production,
Ethylene-Propylene Rubber Production,
Polysulfide Rubber Production,
Neoprene Production, Epoxy Resins
Production, Ethylene-Propylene Rubber
Production, Acetal Resins Production,
and Hydrogen Fluoride Production.
III. How do I access and review the
facility-specific data?
The facility-specific data for each
source category are available for
download on the RTR webpage at
https://www.epa.gov/ttn/atw/rrisk/
rtrpg.html. The eight source categories
affected by today’s proposal are referred
to as Group 1 of RTR Phase 2. These
data files include detailed information
for each emissions release point at each
facility in the source category. For large
integrated facilities with multiple
processes representing multiple source
categories, it is often difficult to clearly
distinguish the source category to which
each emission point belongs. For this
reason, the data available for download
for each source category include all
emission points for each facility in the
source category, though only the
emission points marked as belonging to
the specific source category in question
were included in the analysis for that
source category.
The data files for each source category
must be downloaded from the RTR Web
page to be viewed (https://www.epa.gov/
ttn/atw/rrisk/rtrpg.html). These are
Microsoft Access files, which require
Microsoft Access to be viewed (if you
do not have Microsoft Access, contact
us by e-mail at RTR@epa.gov). Each file
contains the following information from
the NEI for each facility in the source
category:
mstockstill on PROD1PC66 with PROPOSALS
Facility data
Emissions data
EPA Region .....................................................................................................................................
Tribal Code ......................................................................................................................................
Tribe Name .....................................................................................................................................
State Abbreviation ...........................................................................................................................
County Name ..................................................................................................................................
State County FIPS ..........................................................................................................................
NEI Site ID ......................................................................................................................................
Facility Name ..................................................................................................................................
Location Address ............................................................................................................................
City Name .......................................................................................................................................
State Name .....................................................................................................................................
Zip Code ..........................................................................................................................................
Facility Registry ...............................................................................................................................
State Facility Identifier .....................................................................................................................
SIC Code .........................................................................................................................................
SIC Code Description .....................................................................................................................
NAICS Code ....................................................................................................................................
Facility Category Code ....................................................................................................................
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Pollutant Code.
Pollutant Code Description.
HAP Category Name.
Emissions (TPY).
MACT Code.
MACT Source Category Name.
MACT Flag.
MACT Compliance Status Code.
SCC Code.
SCC Code Description.
Emission Unit ID.
Process ID.
Emission Release Point ID.
Emission Release Point Type Code.
Emission Release Point Type.
Stack Default Flag.
Stack Default Flag Description.
Stack height.
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Facility data
Emissions data
Facility Category .............................................................................................................................
Exit Gas Temperature.
Stack Diameter.
Exit Gas Velocity.
Exit Gas Flow Rate.
Fugitive Length.
Fugitive Width.
Fugitive Angle.
Longitude.
Latitude.
Location Default Flag.
Data Source Code.
Data Source Description.
HAP Emissions Performance Level Code.
HAP Emissions Performance Level Description.
Start Date.
End Date.
More information on these NEI data
fields can be found in the NEI
documentation at https://www.epa.gov/
ttn/chief/net/
2002inventory.html#documentation.
To submit comments on the data
downloaded from the RTR Web page,
complete the following steps:
1. Within this downloaded file, enter
suggested revisions in the data fields
appropriate for that information. The
data fields that may be revised include
the following:
IV. How do I submit suggested data
corrections?
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
improved data if available. When
submitting data, we ask that you
provide documentation of the basis for
the revised values to support any
suggested changes.
Facility data
mstockstill on PROD1PC66 with PROPOSALS
REVISED
REVISED
REVISED
REVISED
REVISED
REVISED
REVISED
REVISED
REVISED
Emissions data
Tribal Code .....................................................................................................................
County Name .................................................................................................................
Facility Name ..................................................................................................................
Location Address ...........................................................................................................
City Name ......................................................................................................................
State Name ....................................................................................................................
Zip Code .........................................................................................................................
Facility Registry Identifier ...............................................................................................
Facility Category Code ...................................................................................................
2. Fill in the following commenter
information fields for each suggested
revision:
• Commenter Name.
• Commenter Organization.
• Commenter E-Mail Address.
• Commenter Phone Number.
• Revision Comments.
3. Gather documentation for any
suggested emissions revisions (e.g.,
performance test reports, material
balance calculations, etc.).
4. Send the entire downloaded file
with suggested revisions in Microsoft()
Access format and all accompanying
documentation to Docket ID No. EPA–
HQ–OAR–2007–0211 (through one of
the methods described in the ADDRESSES
section of this preamble). To answer
questions on navigating through the
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data and to help expedite review of the
revisions, it would also be helpful to
submit revisions to EPA directly at
RTR@epa.gov in addition to submitting
them to the docket.
5. If you are providing comments on
a facility with multiple source
categories, you need only submit one
file for that facility, which should
contain all suggested changes for all
source categories at that facility.
We strongly urge that all data revision
comments be submitted in the form of
updated Microsoft() Access files,
which are provided on the https://
www.epa.gov/ttn/atw/rrisk/rtrpg.html
webpage. Data in the form of written
descriptions or other electronic file
formats will be difficult for EPA to
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REVISED Emissions (TPY).
Emissions Calculation Method Code.
REVISED MACT Code.
REVISED SCC Code.
REVISED Emission Release Point Type.
REVISED Start Date.
REVISED End Date.
Revised Pollutant Code.
REVISED Stack height.
REVISED Exit Gas Temperature.
REVISED Stack Diameter.
REVISED Exit Gas Velocity.
REVISED Exit Gas Flow Rate.
REVISED Longitude.
REVISED Latitude.
REVISED HAP Emissions Performance Level.
translate into the necessary format in a
timely manner.
V. Statutory and Executive Order
Reviews
A. Executive Order 12866, Regulatory
Planning and Review
Under Executive Order 12866 (58 FR
51735, October 4, 1993), this action is a
‘‘significant regulatory action.’’ This
action is a significant regulatory action
because it raises novel legal and policy
issues. Accordingly, EPA submitted this
action to the Office of Management and
Budget (OMB) for review under
Executive Order 12866 and any changes
made in response to OMB
recommendations have been
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documented in the docket for this
action.
B. Paperwork Reduction Act
This action does not impose any new
information collection burden. This
action is proposing no changes to the
existing regulations affecting the eight
source categories affected by today’s
proposal and will impose no additional
information collection burden.
Burden means the total time, effort, or
financial resources expended by persons
to generate, maintain, retain, or disclose
or provide information to or for a
Federal agency. This includes the time
needed to review instructions; develop,
acquire, install, and utilize technology
and systems for the purposes of
collecting, validating, and verifying
information, processing and
maintaining information, and disclosing
and providing information; adjust the
existing ways to comply with any
previously applicable instructions and
requirements; train personnel to be able
to respond to a collection of
information; search data sources;
complete and review the collection of
information; and transmit or otherwise
disclose the information.
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 EPA’s regulations in 40
CFR are listed in 40 CFR part 9.
mstockstill on PROD1PC66 with PROPOSALS
C. Regulatory Flexibility Act
The Regulatory Flexibility Act (RFA)
generally requires an agency to prepare
a regulatory flexibility analysis of any
rule subject to notice and comment
rulemaking requirements under the
Administrative Procedure Act or any
other statute unless the agency certifies
that the rule will not have a significant
economic impact on a substantial
number of small entities. Small entities
include small businesses, small
organizations, and small governmental
jurisdictions.
For purposes of assessing the impact
of today’s proposed action on small
entities, small entity is defined as: (1) A
small business whose parent company
has fewer than 750 to 1,000 employees,
depending on the size definition for the
affected NAICS code (as defined by
Small Business Administration size
standards); (2) a small governmental
jurisdiction that is a government of a
city, county, town, school district, or
special district with a population of less
than 50,000; and (3) a small
organization that is any not-for-profit
enterprise which is independently
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owned and operated and is not
dominant in its field.
After considering the economic
impact of today’s proposed action on
small entities, we certify that this action
will not have a significant economic
impact on a substantial number of small
entities. The proposed action will not
impose any requirements on small
entities. We are proposing no further
action at this time to revise the
NESHAP. Today’s proposed action
requests public comments on the
residual risk and technology review.
We continue to be interested in the
potential impacts of the proposed action
on small entities and welcome
comments on issues related to such
impacts.
D. Unfunded Mandates Reform Act
Title II of the Unfunded Mandates
Reform Act of 1995 (UMRA), Public
Law 104–4, establishes requirements for
Federal agencies to assess the effect of
their regulatory actions on State, local,
and tribal governments and the private
sector. Under section 202 of the UMRA,
EPA generally must prepare a written
statement, including a cost-benefit
analysis, for proposed and final rules
with ‘‘Federal mandates’’ that may
result in expenditures to State, local,
and tribal governments, in the aggregate,
or to the private sector, of $100 million
or more in any one year. Before
promulgating an EPA rule for which a
written statement is needed, section 205
of the UMRA generally requires EPA to
identify and consider a reasonable
number of regulatory alternatives and
adopt the least costly, most costeffective, or least burdensome
alternative that achieves the objectives
of the rule. The provisions of section
205 do not apply when they are
inconsistent with applicable law.
Moreover, section 205 allows EPA to
adopt an alternative other than the least
costly, most cost-effective, or least
burdensome alternative if the
Administrator publishes with the final
rule an explanation why that alternative
was not adopted. Before EPA establishes
any regulatory requirements that may
significantly or uniquely affect small
governments, including tribal
governments, it must have developed
under section 203 of the UMRA a small
government agency plan. The plan must
provide for notifying potentially
affected small governments, enabling
officials of affected small governments
to have meaningful and timely input in
the development of EPA regulatory
proposals with significant Federal
intergovernmental mandates, and
informing, educating, and advising
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70557
small governments on compliance with
the regulatory requirements.
EPA has determined that the
proposed action does not contain a
Federal mandate that may result in
expenditures of $100 million or more
for State, local, and tribal governments
in the aggregate, or to the private sector
in any one year. The rule imposes no
enforceable duty on State, local, or tribal
governments, or the private sector.
Thus, today’s proposed action is not
subject to the requirements of sections
202 and 205 of the UMRA.
In addition, EPA has determined that
the proposed action contains no
regulatory requirements that might
significantly or uniquely affect small
governments, because it contains no
requirements that apply to such
governments or impose obligations
upon them.
E. Executive Order 13132, Federalism
Executive Order 13132, entitled
‘‘Federalism’’ (64 FR 43255, August 10,
1999), requires EPA to develop an
accountable process to ensure
‘‘meaningful and timely input by State
and local officials in the development of
regulatory policies that have federalism
implications.’’ ‘‘Policies that have
federalism implications’’ is defined in
the Executive Order to include
regulations that 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.’’
This proposed 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, as specified in
Executive Order 13132. Thus, Executive
Order 13132 does not apply to this
proposed action.
In the spirit of Executive Order 13132,
and consistent with EPA policy to
promote communications between EPA
and State and local governments, EPA
specifically solicits comment on this
proposed action from State and local
officials.
F. Executive Order 13175, Consultation
and Coordination with Indian Tribal
Governments
Executive Order 13175, entitled
‘‘Consultation and Coordination with
Indian Tribal Governments’’ (65 FR
67249, November 9, 2000), requires EPA
to develop an accountable process to
ensure ‘‘meaningful and timely input by
tribal officials in the development of
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regulatory policies that have tribal
implications.’’ This proposed action
does not have tribal implications as
specified in Executive Order 13175. It
will not have substantial direct effect on
tribal governments, on the relationship
between the Federal government and
Indian tribes, or on the distribution of
power and responsibilities between the
Federal government and Indian tribes,
as specified in Executive Order 13175.
Thus, Executive Order 13175 does not
apply to this proposed action.
EPA specifically solicits additional
comment on this proposed rule from
tribal officials.
mstockstill on PROD1PC66 with PROPOSALS
G. Executive Order 13045, Protection of
Children From Environmental Health
Risks and Safety Risks
Executive Order 13045, ‘‘Protection of
Children from Environmental Health
Risks and Safety Risks’’ (62 FR 19885,
April 23, 1997) applies to any rule that:
(1) Is determined to be ‘‘economically
significant’’ as defined under Executive
Order 12866, and (2) concerns an
environmental health or safety risk that
EPA has reason to believe may have a
disproportionate effect on children. If
the regulatory action meets both criteria,
the Agency must evaluate the
environmental health or safety effects of
the planned rule on children, and
explain why the planned regulation is
preferable to other potentially effective
and reasonably feasible alternatives
considered by the Agency.
This proposed rule is not subject to
the Executive Order because it is not
economically significant as defined in
Executive Order 12866, and because the
Agency does not have reason to believe
the environmental health or safety risks
addressed by this action present a
disproportionate risk to children
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21:02 Dec 11, 2007
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because EPA’s risk assessment
demonstrates that the existing
regulations are health protective.
H. Executive Order 13211, Actions
Concerning Regulations That
Significantly Affect Energy Supply,
Distribution, or Use
This proposed rule is not a
‘‘significant energy action’’ as defined in
Executive Order 13211 (66 FR 28355,
May 22, 2001) because it is not likely to
have a significant adverse effect on the
supply, distribution, or use of energy.
Further, we have concluded that this
proposed rule is not likely to have any
adverse energy effects.
I. National Technology Transfer and
Advancement Act
Section 12(d) of the National
Technology Transfer and Advancement
Act of 1995 (NTTAA), Public Law No.
104–113, 12(d) (15 U.S.C. 272 note)
directs EPA to use voluntary consensus
standards (VCS) in its regulatory
activities, unless to do so would be
inconsistent with applicable law or
otherwise impractical. VCS are
technical standards (e.g., materials
specifications, test methods, sampling
procedures, and business practices) that
are developed or adopted by VCS
bodies. The NTTAA directs EPA to
provide Congress, through OMB,
explanations when the Agency decides
not to use available and applicable VCS.
The proposed action does not involve
technical standards. Therefore, EPA is
not considering the use of any VCS. EPA
welcomes comments on this aspect of
the proposed rulemaking and,
specifically, invites the public to
identify potentially applicable VCS and
to explain why such standards should
be used in this proposed action.
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J. Executive Order 12898: Federal
Actions To Address Environmental
Justice in Minority Populations and
Low-Income Populations
Executive Order 12898 (59 FR 7629,
February 16, 1994) establishes Federal
executive policy on environmental
justice. Its main provision directs
Federal agencies, to the greatest extent
practicable and permitted by law, to
make environmental justice part of their
mission by identifying and addressing,
as appropriate, disproportionately high
and adverse human health or
environmental effects of their programs,
policies, and activities on minority
populations and low-income
populations in the United States.
EPA has determined that this
proposed rule will not have
disproportionately high and adverse
human health or environmental effects
on minority or low-income populations
because it does not affect the level of
protection provided to human health or
the environment. This proposed rule
would not relax the control measures on
sources regulated by the rule and,
therefore, would not cause emissions
increases from these sources.
List of Subjects for 40 CFR Part 63
Environmental protection,
Administrative practice and procedures,
Air pollution control, Hazardous
substances, Intergovernmental relations,
Reporting and recordkeeping
requirements.
Dated: December 6, 2007.
Stephen L. Johnson,
Administrator.
[FR Doc. E7–24076 Filed 12–11–07; 8:45 am]
BILLING CODE 6560–50–P
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Agencies
[Federal Register Volume 72, Number 238 (Wednesday, December 12, 2007)]
[Proposed Rules]
[Pages 70543-70558]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E7-24076]
[[Page 70543]]
ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 63
[EPA-HQ-OAR-2007-0211; FRL-8505-1]
RIN 2060-AO16
National Emission Standards for Hazardous Air Pollutant
Emissions: Group I Polymers and Resins (Polysulfide Rubber Production,
Ethylene Propylene Rubber Production, Butyl Rubber Production, Neoprene
Production); National Emission Standards for Hazardous Air Pollutants
for Epoxy Resins Production and Non-Nylon Polyamides Production;
National Emission Standards for Hazardous Air Pollutants for Source
Categories: Generic Maximum Achievable Control Technology Standards
(Acetal Resins Production and Hydrogen Fluoride Production)
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
-----------------------------------------------------------------------
SUMMARY: This proposed rule requests public comment on the residual
risk and technology reviews for eight industrial source categories
regulated by four national emission standards for hazardous air
pollutants (HAP). The eight industrial source categories and the four
national emission standards are listed in Table 3 of this preamble. The
underlying national emission standards that are under review in this
action limit and control HAP.
We are proposing that no revisions to the national emission
standards regulating the eight source categories listed in Table 3 of
this preamble are required at this time under section 112(f)(2) or
112(d)(6) of the Clean Air Act.
DATES: Comments. Comments must be received on or before February 11,
2008.
Public Hearing. If anyone contacts EPA requesting to speak at a
public hearing by December 27, 2007, a public hearing will be held on
January 11, 2008.
ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2007-0211, by one of the following methods:
www.regulations.gov. Follow the on-line instructions for
submitting comments.
E-mail: a-and-r-Docket@epa.gov.
Fax: (202) 566-1741.
Mail: U.S. Postal Service, send comments to: EPA Docket
Center (2822T), Docket ID No. EPA-HQ-OAR-2007-0211, 1200 Pennsylvania
Avenue, NW., Washington, DC 20460. Please include a total of two
copies.
Hand Delivery: In person or by courier, deliver comments
to: EPA Docket Center (2822T), EPA West Building, Room 3334, 1301
Constitution Ave., NW., Washington, DC 20004. Such deliveries are only
accepted during the Docket's normal hours of operation, and special
arrangements should be made for deliveries of boxed information. Please
include a total of two copies.
Instructions: Direct your comments to Docket ID No. EPA-HQ-OAR-
2007-0211. If commenting on the data in the Risk and Technology Review
(RTR) database, please format your comments as described in section III
and IV of this preamble. EPA's policy is that all comments received
will be included in the public docket without change and may be made
available online at www.regulations.gov, including any personal
information provided, unless the comment includes information claimed
to be confidential business information (CBI) or other information
whose disclosure is restricted by statute. Do not submit information
that you consider to be CBI or otherwise protected through
www.regulations.gov or e-mail. The www.regulations.gov Web site is an
``anonymous access'' system, which means EPA will not know your
identity or contact information unless you provide it in the body of
your comment. If you send an e-mail comment directly to EPA without
going through www.regulations.gov, your e-mail 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, EPA recommends that you include your name
and other contact information in the body of your comment and with any
disk or CD-ROM you submit. If EPA cannot read your comment due to
technical difficulties and cannot contact you for clarification, EPA
may not be able to consider your comment. Electronic files should avoid
the use of special characters, any form of encryption, and be free of
any defects or viruses. For additional information about EPA's public
docket visit the EPA Docket Center homepage at https://www.epa.gov/
epahome/dockets.htm.
Docket: All documents in the docket are listed in the
www.regulations.gov index. Although listed in the index, some
information is not publicly available, e.g., CBI or other information
whose disclosure is restricted by statute. Certain other material, such
as copyrighted material, will be publicly available only in hard copy.
Publicly available docket materials are available either electronically
in www.regulations.gov or in hard copy at the EPA Docket Center, Docket
ID No. EPA-HQ-OAR-2007-0211, EPA West Building, Room 3334, 1301
Constitution Avenue, NW., Washington, DC. The Public Reading Room is
open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding
legal holidays. The telephone number for the Public Reading Room is
(202) 566-1744, and the telephone number for the EPA Docket Center is
(202) 566-1742.
FOR FURTHER INFORMATION CONTACT: For questions about this proposed
action, contact Ms. Mary Tom Kissell, Office of Air Quality Planning
and Standards, Sector Policies and Programs Division, Coatings and
Chemicals Group (E143-01), U.S. Environmental Protection Agency,
Research Triangle Park, NC 27711; telephone number: (919) 541-4516; fax
number: (919) 685-3219; and e-mail address: kissell.mary@epa.gov. For
specific information regarding the modeling methodology, contact Ms.
Elaine Manning, Office and Air Quality Planning and Standards, Health
and Environmental Impacts Division, Sector Based Assessment Group
(C539-02), U.S. Environmental Protection Agency, Research Triangle
Park, NC 27711; telephone number: (919) 541-5499; fax number: (919)
541-0840; and e-mail address: manning.elaine@epa.gov. For information
about the applicability of these four national emission standards for
hazardous air pollutants (NESHAP) to a particular entity, contact the
appropriate person listed in Table 1 to this preamble.
Table 1.--List of EPA Contacts for Group I Polymers and Resins, Group II
Polymers and Resins, Acetal Resins Production, and Hydrogen Fluoride
Production
------------------------------------------------------------------------
NESHAP for: OECA Contact \1\ OAQPS Contact \2\
------------------------------------------------------------------------
Polymers and Resins, Group I Scott Throwe (202) David Markwordt
564-7013, (919) 541-0837,
throwe.scott@epa.go markwordt.david@epa
v. .gov.
[[Page 70544]]
Polymers and Resins, Group Scott Throwe (202) Randy McDonald (919)
II. 564-7013, 541-5402,
throwe.scott@epa.go mcdonald.randy@epa.g
v. ov.
Acetal Resins Production.... Marcia Mia (202) 564- David Markwordt
7042, (919) 541-0837,
mia.marcia@epa.gov. markwordt.david@epa.
gov.
Hydrogen Fluoride Production Marcia Mia (202) 564- Bill Neuffer (919)
7042, 541-5435,
mia.marcia@epa.gov. Neuffer.bill@epa.go
v.
------------------------------------------------------------------------
\1\ OECA stands for the EPA's Office of Enforcement and Compliance
Assurance.
\2\ OAQPS stands for EPA's Office of Air Quality Planning and Standards.
SUPPLEMENTARY INFORMATION: Regulated Entities. The eight regulated
industrial source categories that are the subject of today's proposal
are listed in Table 2 to this preamble. Table 2 is not intended to be
exhaustive, but rather provides a guide for readers regarding entities
likely to be affected by the proposed action for the source categories
listed. These standards, and any changes considered in this rulemaking,
would be directly applicable to sources as a Federal program. Thus,
Federal, State, local, and tribal government entities are not affected
by this proposed rule. The regulated categories affected by this action
include:
Table 2.--NESHAP for Eight Industrial Source Categories
------------------------------------------------------------------------
Category NAICS \1\ Code MACT \2\ Code
------------------------------------------------------------------------
Butyl Rubber Production................. 325212 1307
Ethylene-Propylene Rubber Production.... 325212 1313
Polysulfide Rubber Production........... 325212 1332
Neoprene Production..................... 325212 1320
Epoxy Resins Production................. 325211 1312
Non-nylon Polyamides Production......... 325211 1322
Acetal Resins Production................ 325211 1301
Hydrogen Fluoride Production............ 325120 1409
------------------------------------------------------------------------
\1\ North American Industry Classification System.
\2\ Maximum Achievable Control Technology.
To determine whether your facility would be affected, you should
examine the applicability criteria in the appropriate NESHAP. If you
have any questions regarding the applicability of any of these NESHAP,
please contact the appropriate person listed in Table 1 of this
preamble in the preceding FOR FURTHER INFORMATION CONTACT section.
Submitting Comments/CBI. Direct your comments to Docket ID No. EPA-
HQ-OAR-2007-0211. If commenting on changes to the RTR database, please
submit your comments in the format described in sections III and IV of
this preamble. Do not submit CBI to EPA through www.regulations.gov or
e-mail. Instead, send or deliver information identified as CBI only to
the following address: Mr. Roberto Morales, OAQPS Document Control
Officer (C404-02), U.S. Environmental Protection Agency, Office of Air
Quality Planning and Standards, Research Triangle Park, NC 27711,
Attention Docket ID No. EPA-HQ-OAR-2007-0211. Clearly mark the part or
all of the information that you claim to be CBI. For CBI information on
a disk or CD-ROM that you mail to Mr. Morales, mark the outside of the
disk or CD-ROM as CBI and then identify electronically within the disk
or CD-ROM the specific information that is claimed as CBI.
In addition to one complete version of the comment that includes
information claimed as CBI, a copy of the comment that does not contain
the information claimed as CBI must be submitted for inclusion in the
public docket. If you submit a CD-ROM or disc that does not contain
CBI, mark the outside of the disk or CD-ROM clearly that it does not
contain CBI. Information not marked as CBI will be included in the
public docket and EPA's electronic public docket without prior notice.
If you have any questions about CBI or the procedures for claiming
CBI, please consult the person identified in the FOR FURTHER
INFORMATION CONTACT section. Information marked as CBI will not be
disclosed except in accordance with procedures set forth in 40 CFR part
2.
Worldwide Web (WWW). In addition to being available in the docket,
an electronic copy of today's proposed action will also be available on
the WWW through the Technology Transfer Network (TTN). Following
signature, a copy of the proposed action will be posted on the TTN(s
policy and guidance page for newly proposed or promulgated rules at the
following address: https://www.epa.gov/ttn/oarpg/. The TTN provides
information and technology exchange in various areas of air pollution
control.
As discussed in more detail in sections III and IV of this
preamble, additional information is available on the Risk and
Technology Review Phase II webpage at https://www.epa.gov/ttn/atw/rrisk/
rtrpg.html. This information includes source category descriptions and
detailed emissions and other data that were used as inputs to the risk
assessments.
Public Hearing. If a public hearing is held, it will begin at 10
a.m. and will be held at EPA's campus in Research Triangle Park, North
Carolina, or at an alternate facility nearby. Persons interested in
presenting oral testimony or inquiring as to whether a public hearing
is to be held should contact Ms. Mary Tom Kissell, Office of Air
Quality Planning and Standards, Sector Policies and Programs Division,
Coatings and Chemicals Group (E143-01), U.S. Environmental Protection
Agency, Research Triangle Park, NC 27711; telephone number: (919) 541-
4516.
Outline. The information presented in this preamble is organized as
follows:
I. Background
[[Page 70545]]
A. What is the statutory authority for this action?
B. Overview of the Four NESHAP
C. How did we estimate risk posed by the eight source
categories?
D. What are the conclusions of the risk review?
E. What are the conclusions of the technology review?
II. Proposed Action
III. How do I access and review the facility-specific data?
IV. How do I submit suggested data corrections?
V. Statutory and Executive Order Reviews
A. Executive Order 12866, Regulatory Planning and Review
B. Paperwork Reduction Act
C. Regulatory Flexibility Act
D. Unfunded Mandates Reform Act
E. Executive Order 13132, Federalism
F. Executive Order 13175, Consultation and Coordination With
Indian Tribal Governments
G. Executive Order 13045, Protection of Children From
Environmental Health Risks and Safety Risks
H. Executive Order 13211, Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
I. National Technology Transfer and Advancement Act
J. Executive Order 12898, Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations
I. Background
A. What is the statutory authority for this action?
Section 112 of the Clean Air Act (CAA) establishes a comprehensive
regulatory process to address emissions of hazardous air pollutants
(HAP) from stationary sources. In accordance with CAA section 112(c),
EPA identifies categories and subcategories of major sources that emit
one or more of the HAP listed in CAA section 112(b). CAA section 112(d)
then calls for EPA to promulgate national technology-based emission
standards for each listed category or subcategory of sources. For
``major sources'' that emit or have the potential to emit any single
HAP at a rate of 10 tons or more per year or any combination of HAP at
a rate of 25 tons or more per year, these technology-based standards
must reflect the maximum reductions of HAP achievable (after
considering cost, energy requirements, and non-air health and
environmental impacts) and are commonly referred to as maximum
achievable control technology (MACT) standards. The source categories
listed in Table 3 to this preamble are eight source categories for
which we have promulgated MACT standards.
In what we refer to as the technology review, CAA section 112(d)(6)
then requires EPA to review the CAA section 112(d) technology-based
standards and to revise them ``as necessary, taking into account
developments in practices, processes, and control technologies,'' no
less frequently than every 8 years. If we conclude a revision is
necessary, we must revise the standards.
The residual risk review is described in section 112(f) of the CAA.
CAA section 112(f)(2) requires us to promulgate standards for each
category or subcategory of CAA section 112(d) sources ``if promulgation
of such standards is required in order to provide an ample margin of
safety to protect public health * * * or to prevent, taking into
consideration costs, energy, safety, and other relevant factors, an
adverse environmental effect.\1\ If standards promulgated pursuant to
CAA section 112(d) and applicable to a category or subcategory of
source emitting a pollutant (or pollutants) classified as a known,
probable or possible human carcinogen do not reduce lifetime excess
cancer risks to the individual most exposed to emissions from a source
in the category or subcategory to less than 1-in-1 million, the
Administrator shall promulgate standards under this subsection'' for
the source category (or subcategory). EPA's framework for making ample
margin of safety determinations under CAA section 112(f)(2) is provided
in the Benzene NESHAP (54 FR 38044, September 14, 1989) and was
codified by Congress in CAA section 112(f)(2)(B).
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\1\ Adverse environmental effect is defined in CAA section
112(a)(7) 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.
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B. Overview of the Four NESHAP
The eight industrial source categories and four NESHAP that are the
subject of today's proposal are listed in Table 3 to this preamble.
NESHAP limit and control HAP that are known or suspected to cause
cancer or have other serious human health or environmental effects. The
NESHAP for these eight source categories generally required
implementation of technologies such as steam strippers and
incineration.
Table 3.--List of National Emission Standards for Hazardous Air Pollutants (NESHAP) and Industrial Source
Categories Affected by Today's Proposal
----------------------------------------------------------------------------------------------------------------
Source categories
Title of NESHAP affected by today's Promulgated rule Compliance NESHAP as referred
proposal reference date to in this preamble
----------------------------------------------------------------------------------------------------------------
NESHAP for Group I Polymers and Polysulfide Rubber 61 FR 46905 (09/05/ 07/31/1997 Polymers and Resins
Resins\1\. Production. 1996). I.
Ethylene Propylene
Rubber Production.
Butyl Rubber
Production.
Neoprene Production
NESHAP for Epoxy Resins Epoxy Resins 60 FR 12670 (03/08/ 03/03/1998 Polymers and Resins
Production and Non-nylon Production. 1995). II.
Polyamides Production. Non-nylon
Polyamides
Production..
NESHAP for GMACT\2\.............. Acetal Resins 64 FR 34853 (06/29/ 06/29/2002 GMACT.
Production. 1999).
Hydrogen Fluoride
Production..
----------------------------------------------------------------------------------------------------------------
\1\ The Polymers and Resins I NESHAP regulates nine source categories. We are performing the residual risk and
technology review for four of them in this proposal. We will address the remaining five source categories in a
separate risk and technology review rulemaking.
\2\ The source categories subject to the standards in the GMACT NESHAP are Acetal Resins Production and Hydrogen
Fluoride Production.
[[Page 70546]]
1. Polymers and Resins I
The Polymers and Resins I NESHAP applies to major sources and
regulates HAP emissions from nine source categories. In today's
proposal, we address four of the Polymer and Resins I sources
categories--Polysulfide Rubber Production, Ethylene Propylene Rubber
Production, Butyl Rubber Production, and Neoprene Production. HAP
emissions from these processes can be released from storage tanks,
process vents, equipment leaks, and wastewater operations.
These four source categories involve the production of elastomers
(i.e., synthetic rubber). An elastomer is a synthetic polymeric
material that can stretch at least twice its original length and then
return rapidly to approximately its original length when released.
Elastomers have long, flexible, chainlike molecules that are able to
undergo rapid rotation (i.e., flex) as a result of thermal agitation.
Elastomers are produced via a polymerization process, in which monomers
undergo intermolecular chemical bonds to form an insoluble, three-
dimensional network (i.e., a polymer). Generally, the production of
elastomers entails four processes: (1) Raw material (i.e., solvent)
storage and refining; (2) polymer formation in a reactor (either via
the solution process, where monomers are dissolved in an organic
solvent, or the emulsion process, where monomers are dispersed in water
using a soap solution); (3) stripping and material recovery; and (4)
finishing (i.e., blending, aging, coagulation, washing, and drying
processes).
a. Polysulfide Rubber Production. Polysulfide rubber is a synthetic
rubber produced by the reaction of sodium sulfide and p-dichlorobenzene
(1,4-dichlorobenzene) at an elevated temperature in a polar solvent.
Polysulfide rubber is resilient, resistant to solvents, and has low
temperature flexibility, facilitating its use in seals, caulks,
automotive parts, rubber molds for casting sculpture, and other
products.
During the development of the NESHAP, we identified one polysulfide
rubber production facility as a major source and subject to the
Polymers and Resins I NESHAP. This facility consisted of raw material
storage vessels and was designated as a major source because it was co-
located with another source. This polysulfide facility has been
dismantled and we are not aware of any other facilities currently
subject to the NESHAP. (Even though no polysulfide rubber facilities
are currently in operation, we completed a risk analysis based on the
available information on this facility as of 2002.) The only HAP
reported for this category in the 2002 National Emissions Inventory
(NEI) was methylene diphenyl diisocyanate.
b. Ethylene Propylene Rubber Production. Ethylene propylene
elastomer is an elastomer prepared from ethylene and propylene
monomers. Common uses for these elastomers include radiator and heater
hoses, weather stripping, door and window seals for cars, construction
plastics blending, wire and cable insulation and jackets, and single-
ply roofing membranes.
We believe five ethylene propylene rubber production facilities are
currently subject to the Polymers and Resins I NESHAP. Hexane, which is
the HAP used as the solvent at three of the plants, accounts for the
majority of the HAP emissions from these facilities (over 95 percent of
the total HAP emissions by mass). These facilities also reported
relatively small emissions of ethyl chloride, ethylene glycol, and
hydrogen chloride. Two facilities do not use hexane in their processes.
One facility uses toluene instead of hexane as a solvent and the other
facility uses a gas-phase process where methanol is the only HAP
emitted.
c. Butyl Rubber Production. The Butyl Rubber Production source
category includes any facility that manufactures copolymers of
isobutylene and isoprene. Butyl rubber is very impermeable to common
gases and resists oxidation. A specialty group of butyl rubbers are
halogenated butyl rubbers, which are produced commercially by
dissolving butyl rubber in hydrocarbon solvent and contacting the
solution with gaseous or liquid elemental halogens such as chlorine or
bromine. Halogenated butyl rubber resists aging to a higher degree than
the nonhalogenated type and is more compatible with other types of
rubber. Uses for butyl rubber include tires, tubes, and tire products;
automotive mechanical goods; adhesives, caulks, and sealants; and
pharmaceutical uses.
We believe two butyl rubber production facilities are currently
subject to the Polymers and Resins I NESHAP. The primary HAP emitted
from butyl rubber production facilities are methyl chloride (53 percent
of the total HAP emissions by mass) and hydrochloric acid (34 percent).
Hexane is also emitted from the production of halobutyl rubber, and it
makes up around 13 percent of the total HAP emissions from the
category.
d. Neoprene Production. Neoprene is a polymer of chloroprene.
Neoprene was originally developed as an oil-resistant substitute for
natural rubber, and its properties allow its use in a wide variety of
applications including wetsuits, gaskets and seals, hoses and tubing,
plumbing fixtures, adhesives, and other products.
We believe that one neoprene production facility is currently
subject to the Polymers and Resins I NESHAP. The primary HAP emitted by
production are chloroprene and toluene, with chloroprene accounting for
over 80 percent of the total emissions.
2. Polymers and Resins II
The Polymers and Resins II NESHAP applies to major sources and
regulates HAP emissions from two source categories--epoxy resins
production and non-nylon polyamides production. HAP emissions from
these source categories can be released from storage tanks, process
vents, equipment leaks, and wastewater operations.
a. Epoxy Resins Production. The Epoxy Resins Production source
category generates HAP emissions from the manufacture of basic liquid
epoxy resins used in the production of glues, adhesives, plastic parts,
and surface coatings. This source category does not include specialty
or modified epoxy resins.
We believe three epoxy resins production facilities are currently
subject to the Polymers and Resins II NESHAP. The HAP emitted in the
greatest quantity by mass from these facilities are epichlorohydrin
(referred to by its synonym 1-chloro-2,3-epoxypropane in the NEI and in
the accompanying emissions summary table) and chlorobenzene. The total
emissions for these two HAP account for approximately 87 percent of the
total HAP mass emitted by the facilities regulated by the NESHAP.
Epichlorohydrin is emitted in the greatest quantity and is reported as
an emission of all three facilities. Other HAP such as phenol, xylenes,
ethyl benzene, propylene dichloride, allyl chloride, 1,3-
dichloropropene, glycol ethers, methyl chloride, toluene, acrolein,
benzyl chloride, and ethyl acrylate are emitted in smaller quantities.
All the other HAP are reported as emissions by only one or two of the
facilities.
b. Non-nylon Polyamides Production. The Non-nylon Polyamides
Production source category generates HAP emissions from the manufacture
of epichlorohydrin cross-linked non-nylon polyamides used primarily by
the paper industry as an additive to paper products. Natural polymers,
such as those contained in paper products, have
[[Page 70547]]
little cross-linking, which allows their fibers to change position or
separate completely when in contact with water. The addition of
epichlorohydrin cross-linked non-nylon polyamides to these polymers
causes the formation of a stable polymeric web among the natural
fibers. Because the polymeric web holds the fibers in place even in the
presence of water, epichlorohydrin cross-linked non-nylon polyamides
are also referred to as wet-strength resins.
We believe four non-nylon polyamides production facilities are
currently subject to the Polymers and Resins II NESHAP. Epichlorohydrin
(64 percent) and hydrochloric acid (36 percent) are the only HAP
emitted from this category.
3. GMACT--Acetal Resins Production
The GMACT set national emission standards for certain source
categories consisting of five or fewer facilities. The basic purpose of
the GMACT approach was to use public and private sector resources
efficiently, and to promote regulatory consistency and predictability
in the MACT standards development.
Emission sources from acetal resin production include storage
vessels that hold process feed materials, process vents, process
wastewater treatment systems, and equipment leaks from compressors,
agitators, pressure relief devices, sampling connection systems,
valves, connectors, and instrumentation systems. The storage vessels
associated with acetal resin production are primarily used for storage
of solvents. Back end process vent emissions occur from reactor units,
mixing vessels, solvent recovery operations, and other operations.
Acetal resins are characterized by the use of formaldehyde in the
polymerization process to manufacture homopolymers or copolymers of
alternating oxymethylene units. Acetal resins, also known as
polyoxymethylenes, polyacetals, or aldehyde resins, are a type of
plastic possessing relatively high strength and rigidity without being
brittle. They have good frictional properties and are resistant to
moisture, heat, fatigue, and solvents. Acetal resins are used as parts
in a variety of industrial applications, e.g., gears, bearings,
bushings, and various other moving parts in appliances and machines,
and in a range of consumer products, e.g., automotive door handles,
seat belt components, plumbing fixtures, shaver cartridges, zippers,
and gas tank caps.
We believe three facilities are currently subject to the acetal
resins production provisions in the GMACT. The primary HAP emitted by
acetal resin production are formaldehyde and methanol, which make up 92
percent of the total HAP emissions by mass.
4. GMACT--Hydrogen Fluoride Production
The Hydrogen Fluoride Production source category includes any
facility engaged in the production and recovery of hydrogen fluoride by
reacting calcium fluoride with sulfuric acid. Potential sources of HAP
emissions at hydrogen fluoride production facilities include: Process
vents on hydrogen fluoride recovery and refining equipment, storage
vessels used to store hydrogen fluoride, bulk loading of tank trucks
and tank rail cars, leaks from hydrogen fluoride handling equipment,
and reaction kiln seal leaks. The only HAP emitted from the processes
in this source category is hydrogen fluoride. We believe two facilities
are currently subject to the hydrogen fluoride production provisions in
the GMACT.
C. How did we estimate risk posed by the eight source categories?
To support the proposed decisions presented in today's notice, EPA
conducted an inhalation risk assessment \2\ that provided estimates of
maximum individual cancer risk, cancer risk distribution within the
exposed populations, cancer incidence, hazard indices for chronic
exposures to HAP with non-cancer health effects, and hazard quotients
(HQ) for acute exposures to HAP with non-cancer health effects. The
risk assessment consisted of six primary activities: (1) Establishing
the nature and magnitude of emissions from the sources of interest, (2)
identifying the emissions release characteristics (e.g., stack
parameters), (3) conducting dispersion modeling to estimate the
concentrations of HAP in ambient air, (4) estimating long-term and
short-term inhalation exposures to individuals residing within 50 km of
the modeled sources, (5) estimating individual and population-level
risks using the exposure estimates and quantitative dose-response
information, and (6) characterizing risk. In general the risk
assessment followed a tiered, iterative approach, beginning with a
conservative screening-level analysis and, where the screening analysis
indicated the potential for non-negligible risks, following that with
more refined analyses. The following sections summarize the results of
these efforts.
---------------------------------------------------------------------------
\2\ For more information on the risk assessment inputs and
models, see ``Residual Risk Assessment for Eight Source
Categories,'' available in the docket.
---------------------------------------------------------------------------
1. Emissions Data
For the Ethylene Propylene Rubber Production, Butyl Rubber
Production, Neoprene Production, Epoxy Resins Production, and Non-nylon
Polyamides Production source categories, we relied primarily on
emissions data and emissions release characteristic data we collected
directly from industry. We reviewed these data and consider them to be
the best emissions and emissions release characteristic data available
for these five source categories.
For the remaining three source categories, Polysulfide Rubber
Production, Acetal Resins Production, and Hydrogen Fluoride Production,
we relied primarily on data in the 2002 NEI Final Inventory,\3\ Version
1 (made publicly available on February 26, 2006). For the Polysulfide
Rubber source category, the data in the 2002 NEI were used without
further investigation because the only facility in the source category
closed in 2002. For the Acetal Resins and Hydrogen Fluoride source
categories, the 2002 NEI data were supplemented with information from
industry and, for one hydrogen fluoride facility, with information from
the State permitting agency.
---------------------------------------------------------------------------
\3\ The National Emission Inventory (NEI) is a database that
contains information about sources that emit criteria air pollutants
and their precursors, and HAP. The database includes estimates of
annual air pollutant emissions from point, nonpoint, and mobile
sources in the 50 States, the District of Columbia, Puerto Rico, and
the Virgin Islands. EPA collects this information and releases an
updated version of the NEI database every 3 years.
---------------------------------------------------------------------------
In response to an advanced notice of proposed rulemaking \4\ we
published on March 29, 2007, we received comments on emissions data and
emissions release characteristics data for an acetal resins production
facility, two ethylene propylene production facilities, and a neoprene
production facility. We will include these comments in the docket for
this proposal (docket ID EPA-HQ-OAR-2007-0211) and will evaluate them
with other comments we receive in response to today's proposal. The
data files for the eight source categories, which are posted on the RTR
webpage and are described in Section III of this preamble, will include
the new data provided by the commenters.
---------------------------------------------------------------------------
\4\ Risk and Technology Review, Phase II, Group 2 at 72 FR
29287.
---------------------------------------------------------------------------
Emissions data and emissions release characteristics data for these
eight source categories are documented in the docket in ``Documentation
of Emissions Data and Emissions Release
[[Page 70548]]
Characteristics Data Used for the RTR Group 1.'' We specifically
request comment on whether the facilities listed in our emissions data
set accurately reflect the universe of sources within the source
categories. For example, are there records remaining in the data set
that are not part of the relevant source category or any missing
emissions data that should be included for the relevant source
category?
2. Risk Assessment
Both long-term and short-term inhalation exposure concentrations
and health risk from each of the eight source categories addressed in
today's proposal were estimated using the Human Exposure Model
(Community and Sector HEM-3 version 1.1.0). The HEM-3 model performs
three main operations: Dispersion modeling, estimation of population
exposure, and estimation of human health risks. The dispersion model
used by HEM-3 is AERMOD, which is one of EPA's preferred models for
assessing pollutant concentrations from industrial facilities.\5\
---------------------------------------------------------------------------
\5\ Environmental Protection Agency. 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.
---------------------------------------------------------------------------
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 are used for dispersion
calculations. This library includes 1 year of hourly surface and upper
air observations for 130 meteorological stations, selected to provide
thorough coverage of the U.S. and Puerto Rico. A second library of U.S.
Census Bureau census block internal point locations and populations
provides the basis of human exposure calculations (Census, 2000). In
addition, the census library includes the elevation and controlling
hill height for each census block, which are also used in dispersion
calculations. A third library of pollutant unit risk factors and other
health benchmarks is used to estimate health risks. These risk factors
and health benchmarks are the latest values recommended by EPA for HAP
and other toxic air pollutants, and are discussed in more detail below.
These values are available at https://www.epa.gov/ttn/atw/toxsource/
summary.html.
The risk assessment for chronic exposures used the estimated annual
average ambient air concentration of each HAP emitted by each source
for which we have emissions data in the source category at each nearby
census block \6\ centroid as a surrogate for the chronic inhalation
exposure concentration for all the people who reside in that census
block. We calculated the maximum individual risk for each facility as
the risk associated with a lifetime (70-year) exposure to the maximum
concentration at the centroid of an inhabited census block. Individual
cancer risks were calculated as the lifetime exposure to the ambient
concentration of each HAP multiplied by its Unit Risk Estimate (URE);
total cancer risks were the sum of the risks of each carcinogenic HAP
(including known, probable, and possible carcinogens) emitted by the
modeled source. Air concentrations of HAP from sources other than the
modeled source were not estimated. Total cancer incidence and the
distribution of individual cancer risks across the population within 50
kilometers of any source were also estimated as part of these
assessments by summing individual risks. We are using 50 kilometers to
be consistent with both the analysis supporting the 1989 Benzene NESHAP
(54 FR 38044) and the limitations of Gaussian dispersion modeling.
---------------------------------------------------------------------------
\6\ A typical census block is comprised of approximately 40
people or about 10 households.
---------------------------------------------------------------------------
To assess risk of noncancer health effects from chronic exposures,
we summed the HQ for each HAP that affects a common target organ system
to obtain the hazard index (HI) for that target organ system (or target
organ-specific hazard index, TOSHI), where the HQ is the estimated
exposure divided by the chronic reference level (e.g., the U.S. EPA
Reference Concentration (RfC) which is provided through the Integrated
Risk Information System (IRIS)).
Health protective screening estimates of acute exposures and risks
were also evaluated for each HAP at any location off-site of each
facility (i.e., not just the census block centroids) assuming the
combination of a peak (hourly) emission rate and hourly dispersion
conditions for the 1991 calendar year that would tend to maximize
exposure. In each case, acute HQ were calculated using best available
short-term health indices. We assumed that 10 times the average annual
hourly emission rate represented a health protective emissions estimate
to evaluate acute exposures and risks for these initial screens. The
factor of 10 is intended to cover routinely variable emissions and
startup, shutdown, and malfunction emissions. We chose to use a factor
of 10 based on: (1) Engineering judgment, and (2) a review of short-
term emissions data that compared hourly and annual emissions data for
volatile organic compounds for all facilities in a heavily-
industrialized 4-county area (Harris, Galveston, Chambers, and Brazoria
Counties, TX) over an 11-month time period in 2001.\7\ Most peak
emission events were less than twice the annual average hourly emission
rate and the highest peak emission event was 8.5 times the annual
average hourly emission rate. We request comment on the interpretation
of these data and the appropriateness of using a factor of 10 times the
average annual hourly emission rate in these acute exposure screening
assessments.
---------------------------------------------------------------------------
\7\ See https://www.tceq.state.tx.us/compliance/field_ops/eer/
index.html or docket to access the source of these data.
---------------------------------------------------------------------------
In cases where acute HQ values from the screening step were less
than or equal to one, acute impacts were deemed negligible and no
further analysis was performed. In the cases where an acute HQ from the
screening step was greater than one, site-specific data were sought to
develop a more refined estimate of the potential for acute impacts of
concern. These data refinements included using a better representation
of the peak-to-mean hourly emissions ratio (instead of using the
default factor of 10) and using the site-specific facility layout to
distinguish facility property from an area where the public could be
exposed. The screening analysis resulted in an HQ less than or equal to
one for all of the source categories except Acetal Resins Production
and Hydrogen Fluoride Production. The specific refinements used for
acetal resins production and hydrogen fluoride production are described
in the results section for the two source categories.
We engaged in a consultation with a panel from the Science Advisory
Board (SAB) on the ``Risk and Technology Review (RTR) Assessment Plan''
in December of 2006. The results of this consultation were transmitted
to us in June 2007 in a letter from the SAB which also contained a
summary listing of the key messages from the panel. The letter is
available from the docket and from https://www.epa.gov/sab/pdf/sab-07-
003_response_04-20-07.pdf. In developing the risk assessments for the
eight source categories covered by this proposal, we followed the RTR
Assessment Plan, addressing the key recommendations from the panel,
where appropriate and relevant to these assessments, but not the
individual recommendations from each panel member. Our responses to
each of the SAB's key recommendations are summarized in an appendix to
the
[[Page 70549]]
``Residual Risk Assessment for Eight Source Categories,'' available in
the docket.
3. Noncancer Inhalation Reference Values
The most appropriate noncancer inhalation reference values for
chronic durations in the Residual Risk Program are in order of
preference: (1) The RfC which is provided through the IRIS; (2) the
Agency for Toxic Substances and Disease Registry Chronic Minimal Risk
Levels; or (3) California Office of Environment and Human Health
Assessment's chronic Reference Exposure Level (REL).
No such hierarchy was developed for acute noncancer reference
values. Instead, we use acute inhalation values from multiple sources
because the various assessments are based on methods that are different
enough to render them not directly comparable, nor does any one set of
reference values provide coverage across the majority of chemicals. We
looked to reference values developed for other purposes, such as
Reference Exposure Levels (REL), Acute Exposure Guideline Levels
(AEGLs), and Emergency Response Planning Guideline (ERPGs).
The acute REL (https://www.oehha.ca.gov/air/pdf/acuterel.pdf) is
defined as the concentration level at or below which no adverse health
effects are anticipated for a specified exposure duration. The REL
incorporates factors to address data gaps, uncertainty, and to protect
the most sensitive individuals in the population, and exceeding the REL
does not automatically indicate an adverse health impact.
The AEGL-1 is ``the airborne concentration (expressed as ppm or mg/
m\3\) 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.''
The AEGL values are designed to be applicable to the general
population, including sensitive subgroups; however, as stated in the
AEGL guidelines and the definitions, ``it is recognized that certain
individuals, subject to unique and idiosyncratic responses, could
experience effects at concentrations below the corresponding AEGL.''
The National Research Council states that ``[t]he primary purpose of
the AEGL program and the NAC/AEGL Committee is to develop guideline
levels for once-in-a-lifetime, short-term exposures to airborne
concentrations of acutely toxic, high-priority chemicals.'' \8\
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\8\ See Standing Operating Procedures for Developing Acute
Exposure Guideline Levels for Hazardous Chemicals (2001, National
Academies Press, Washington, DC, page 21, PURPOSE AND OBJECTIVES OF
THE AEGL PROGRAM AND THE NAC/AEGL COMMITTEE; https://books.nap.edu/
openbook.php?record_id=10122&page=21).
---------------------------------------------------------------------------
The ERPG-1, developed specifically for emergency response
situations, is 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 perceiving a clearly defined, objectionable odor. The ERPG
documentation also states that ``in all populations there are
hypersensitive individuals who will show adverse responses at exposure
concentrations far below levels where most individuals normally would
respond.''
The AEGL and ERPG values include three levels of severity generally
referred to as mild, severe, and lethal. In contrast, the REL
represents an exposure at which no adverse effects are expected. For
many chemicals (e.g., ethylene oxide and phosgene) the available
information does not allow development of a mild effect AEGL or ERPG.
AEGL and ERPG values are usually established at higher exposure levels
than Acute California REL reference values. Exceedances of REL, AEGL,
or ERPG values in the context of a residual risk assessment should be
interpreted on a case-by-case basis.
4. Consideration of Actual and Allowable Emissions
Generally, the emissions values in our data set represent actual
emission levels. We discussed the use of both allowable and actual
emissions in the final Coke Oven Batteries residual risk rule (70 FR
19998-19999, April 15, 2005) and in the proposed and final Hazardous
Organic NESHAP (HON) residual risk rules (71 FR 34428, June 14, 2006,
and 71 FR 76603, December 21, 2006, respectively). In those previous
actions, we noted that modeling the allowable levels of emissions
(i.e., the highest emission levels that could be emitted while still
complying with the MACT requirements) is inherently reasonable since
they reflect the maximum level sources could emit and still comply with
national emission standards. But we also explained that it is
reasonable to consider actual emissions, where such data are available,
in both steps of the Benzene NESHAP analysis. Doing so avoids
overestimating emissions and their associated health risks and accounts
for how sources typically strive to perform better than required by
standards to allow for process variability and to prevent exceeding
standards due to emissions increases on individual days. Failure to
consider these data in risk assessments, we said, would unrealistically
inflate actual risk levels. 71 FR at 76609.
For the eight source categories addressed in this package, we do
not have information regarding allowable emissions. This is similar to
the circumstance we faced in the HON. In the preamble to the HON
proposed rule, we acknowledged that there is some uncertainty regarding
the difference between actual and allowable emissions. We also
explained in the HON preamble that it was not possible to estimate
allowable emissions for all emission points from the available
information, but that for equipment leaks, which represent the most
significant impact on cancer risk at HON facilities, the actual and
allowable emissions are likely the same. We further concluded that
there was no evidence of substantial overcontrol, such that actual
emissions would not be a reasonable approximation of allowable
emissions, and that there was no evidence that the sources subject to
the HON could make changes that would result in a substantial increase
of emissions, and thus risk, while still complying with the MACT.
Therefore, we concluded for the HON final rule that basing the analysis
on actual emissions provided an acceptable method for determining the
remaining risks to public health and the environment after application
of the MACT standards.
The production processes for polymers and resins use the same
process equipment and air pollution control equipment as HON processes.
Thus, we believe we can draw the same conclusions for polysulfide
rubber production, ethylene propylene rubber production, butyl rubber
production, neoprene rubber production, epoxy resins production, non-
nylon polyamides production, and acetal resins as we did for the HON--
that estimating risk using actual emissions will reasonably reflect the
risk after application of the relevant MACT standards.
For the Hydrogen Fluoride Production source category, we expect
actual and allowable emissions to be similar, if not the same. Hydrogen
fluoride facilities employed stringent controls prior to the
development of the MACT standards (we based the MACT standards on these
pre-MACT controls) and we have no
[[Page 70550]]
reason to believe control performance will decline.
We believe the differences between actual and allowable emissions
are likely insignificant for these eight source categories and that
using the actual emission levels results in a reasonable approximation
of the allowable emissions. Therefore, we conclude that the risk
assessment results using actual emissions closely approximate those for
an assessment using allowable emissions and that the difference would
not be likely to substantially affect the estimated risk associated
with exposure to HAP emitted by any of the eight source categories.
Nevertheless, if commenters have data that demonstrate that allowable
emissions could be higher or lower than actual emissions for these
eight source categories we request the submission of this data.
5. Adverse Environmental Effects Assessment
None of the eight source categories emit persistent or
bioaccumulative HAP; therefore, EPA's assessment of environmental
effects evaluated only non-persistent and non-bioaccumulative HAP.\9\
For animal populations, the potential for significant direct adverse
environmental effects due to non-persistent and non-bioaccumulative HAP
was evaluated implicitly by checking for exceedances of any human
health inhalation dose-response limit values near the assessed
facilities. \10\ Because these values generally reflect the inclusion
of uncertainty factors \11\ (often 100 or 1,000), the human threshold
values are generally believed to be significantly lower than any levels
which have been shown to cause an adverse effect in an exposed animal.
Therefore, if the maximum inhalation hazard in an ecosystem is below
the level of concern for humans, we have concluded that, in general,
environmental receptors should be at little risk of adverse effects due
to airborne exposures.
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\9\ Persistent and bioaccumulative HAP are those which persist
in the environment and which also may bioaccumulate or biomagnify in
food chains.
\10\ While environmental effects thresholds are often available
for HAP in water and soil, very few are available for direct
airborne exposures.
\11\ The uncertainty factors account for various data
methodological uncertainties, for example, most inhalation dose-
response limit values are derived from studies of laboratory
animals.
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One possible exception is pollutants that may directly impact
various species of vegetation. For the seven polymers and resins
production source categories affected by today's proposal, we have no
scientific data, informal observations or other information that would
indicate any concern for adverse environmental effects of HAP on
vegetation at the expected air concentrations.
For the two facilities in the Hydrogen Fluoride Production source
category (both of which emit hydrogen fluoride), we have some general
information on the possible effects of hydrogen fluoride on vegetation
at ambient concentrations well below the California chronic REL value
of 14 microgram per cubic meter ([mu]g/m\3\). In separate and unrelated
studies, air concentrations of hydrogen fluoride greater than about 1
[mu]g/m\3\ have been shown to adversely affect specific sensitive plant
species. \12\ We note that responses to hydrogen fluoride are highly
variable among plant species and responses may be influenced by co-
exposures to other air pollutants. In this particular case, the maximum
chronic ambient concentration estimated in the vicinity of the hydrogen
fluoride production facilities was about 1.5 [mu]g/m\3\, meaning that
concentrations of hydrogen fluoride in all areas other than the maximum
point are lower than 1.5 [mu]g/m\3\, and perhaps substantially lower as
the distance from the point of release increases. Because the
spatially-averaged hydrogen fluoride concentration within several
kilometers of each facility is likely well below 1 [mu]g/m\3\, we are
led to the conclusion that any significant and widespread adverse
environmental effects on plants due to hydrogen fluoride emissions are
unlikely. Further, we have no information suggesting that there are
currently observed adverse impacts of hydrogen fluoride emissions on
plants surrounding the two facilities.
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\12\ 1 [mu]g/m\3\ was the lowest concentration for which adverse
effects were observed in the most sensitive flora for which data
exists. We note that the studies were limited to certain species and
1 [mu]g/m\3\ cannot be interpreted as an appropriate or definitive
concentration level for all plant species. (See ``List of References
for Effects of Hydrogen Fluoride on Vegetation'' in docket.)
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6. Uncertainties in Risk Assessments
Uncertainty and the potential for bias are inherent in all risk
assessments, including those performed for the eight source categories
affected by today's proposal. We reduced some of these uncertainties by
developing a new emissions data set, the RTR database, that is based on
the NEI, but that includes more accurate replacement or supplemental
data for the specific facilities in these eight source categories.
Although uncertainty exists, we believe the risk assessments
performed for the eight source categories most likely overestimate the
potential for risks due to the conservative (i.e., health-protective)
assessment approach. Because these health protective risk assessments
indicate little, if any, potential for significant risk, we believe
they support our proposed decision not to issue residual risk standards
for these eight source categories. A brief discussion of the
uncertainties in the emissions data set, dispersion modeling,
inhalation exposure estimates, and dose-response relationships is
presented in this section of the preamble. A fuller discussion of these
uncertainties is discussed in both the ``Residual Risk Assessment for
Eight Source Categories'' (July 2007) and the ``Risk and Technology
Review (RTR) Assessment Plan'' (November 2006), both of which are
available in the docket.
a. Uncertainties in the RTR Emissions Database. Although the
development of the RTR database involved quality assurance/quality
control processes, the accuracy of emissions values will vary depending
on the source of the data present, incomplete or missing data, errors
in estimating emissions values, and other factors. The emission values
considered in this analysis are annual totals that do not reflect
actual fluctuations during the course of a year (2002) or variations
from year to year. These annual emissions estimates do not consider
operations such as startup/shutdown and malfunctions. The estimates of
health protective short-term emission rates for the screening
assessment were based on a health-protective default assumption
applicable to these source categories (10 times the annual rate). More
refined estimates were used for source categories where the screening
estimates did not ``screen out'' all sources and more specific
information was available.
Facilities in some of the seven polymers and resins source
categories emit chlorinated compounds and use incineration devices,
creating the possibility for the formation of polychlorinated dioxins.
However, we have no test reports or measurements, conducted by
manufacturers or anyone else, indicating the presence of dioxins in the
emissions from any of these source categories and EPA's dioxins
inventory \13\ does not specifically link
[[Page 70551]]
dioxins emissions to any of these source categories. Furthermore, in
our judgment, it is improbable that dioxins are emitted in measurable
amounts from the seven polymers and resins source categories,
especially given the low quantity of particulate matter present.
Therefore, we did not consider dioxins in our assessment of the seven
polymers and resins production source categories. Because no
chlorinated compounds are emitted from the hydrogen fluoride production
source category, we believe there is no possibility for dioxins to be
emitted and we did not consider dioxins in our assessment of the source
category.
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\13\ An Inventory of Sources and Environmental Releases of
Dioxin-Like Compounds in the United States for the Years 1987, 1995,
and 2000. (EPA/600/P-03/002f, Final Report, November 2006). The
dioxins inventory (https://cfpub.epa.gov/ncea/cfm/
recordisplay.cfm?deid=159286) classifies ``rubber manufacturing'' as
an unquantifiable dioxins emission source. A source was defined as
unquantifiable if dioxins releases were possible, but the data were
inadequate to support even rudimentary calculations of emissions.
Furthermore, the process could be very different from the polymers
and resins processes of concern in this proposal.
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Overall we believe that the emissions data considered in this
assessment are the most accurate available representation of the eight
source categories for the stated purpose. Nevertheless, we request
comment on our emissions data set in general, and specifically on our
approach to short-term emissions estimates and on the potential for
dioxins emissions from the facilities in the seven polymers and resins
production source categories affected by today's proposal.
b. Uncertainties in Dispersion Modeling. While the analysis
employed EPA's suggested regulatory dispersion model, AERMOD, there is
uncertainty in ambient concentration estimates associated with EPA's
choice and application of the model. Where possible, model options
(e.g., rural/urban, plume depletion, chemistry) were selected as to
provide an overestimate of ambient air concentrations. However, because
of practicality and data limitation reasons, some factors (e.g.,
meteorology, building downwash) have the potential in some situations
to overestimate or underestimate ambient impacts. For example,
meteorological data were taken from a single year (1991), and facility
locations can be a significant distance from the site where these data
were taken. Despite these uncertainties, we believe that at off-site
locations and census block centroids, the approach considered in the
dispersion modeling analysis should generally yield overestimates of
ambient concentrations.
c. Uncertainties in Inhalation Exposure. The effects of human
mobility on exposures were not included in the assessment.
Specifically, short-term mobility and long-term mobility\14\ between
census blocks in the modeling domain was not considered. As a result,
this simplification will likely bias the assessment toward
overestimating the highest exposures. In addition, the assessment
predicted the chronic exposures at the centroid of each populated
census block as surrogates for the exposure concentrations for all
people living in that block. (On average census blocks are populated by
approximately 40 people.) Using the census block centroid to predict
chronic exposures tends to overpredict exposures for people in the
census block who live further from the facility and underpredict
exposures for people in the census block who live closer to the
facility. Thus, in general, using the census block centroid to predict
chronic exposures leads to a potential understatement or overstatement
of maximum impact and an unbiased estimate of average risk and
incidence.
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\14\ Short-term mobility is movement from one microenvironment
to another over the course of hours or days. Long-term mobility is
movement from one residence to another over the course of a
lifetime.
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The assessments evaluate the cancer inhalation risks associated
with pollutant exposures over a 70-year period, the assumed lifetime of
individuals. In reality, both the length of time that modeled emissions
sources at facilities actually operate (i.e., more or less than 70
years), and the domestic growth or decline of the modeled industry
(i.e., the increase or decrease in the number or size of U.S.
facilities), will influence the risks posed by a given source category.
Depending on the characteristics of the industry, these factors may
result in an overestimate (or possibly an underestimate in the extreme
case where a facility maintains or increases its