Document ID: EPA-HQ-OAR-2007-0211-0023
Agency: epa
Document Type: Rule
Title: 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 Sourc
Posted Date: 2008-12-16T05:00Z

[Federal Register: December 16, 2008 (Volume 73, Number 242)]
[Rules and Regulations]               
[Page 76220-76230]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr16de08-9]                         

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[EPA-HQ-OAR-2007-0211; FRL-8752-5]
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) (Risk and 
Technology Review)

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: This final rule responds to public comments received on the 
proposed rule and announces our decision not to revise four national 
emission standards for hazardous air pollutants that regulate eight 
industrial source categories evaluated in our risk and technology 
review. The four national emission standards and eight industrial 
source categories are: National Emissions Standards for Hazardous Air 
Pollutant Emissions: Group I Polymers and Resins (Polysulfide Rubber 
Production, Ethylene Propylene Rubber Production, Butyl Rubber 
Production, and Neoprene Rubber 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 Acetal Resins Production and National 
Emission Standards for Hazardous Air Pollutants for Hydrogen Fluoride 
Production. The underlying national emission standards that were 
reviewed in this action limit and control hazardous air pollutants.
    On December 12, 2007, we proposed not to revise the national 
emission standards based on our residual risk assessment and technology 
review. After conducting risk and technology reviews, and after 
considering public comments on the proposed rule, we conclude no 
additional control requirements are warranted under section 112(f)(2) 
or 112(d)(6) of the Clean Air Act at this time.

DATES: This final action is effective on December 16, 2008.

ADDRESSES: We have established a docket for this action under Docket ID 
No. EPA-HQ-OAR-2007-0211. All documents in the docket are listed on the 
www.regulations.gov Web site. Although listed in the index, some 
information is not publicly available, e.g., confidential business 
information or other information whose disclosure is restricted by 
statute. Certain other material, such as copyrighted material, is not 
placed on the Internet and will be publicly available only in hard copy 
form. Publicly available docket materials are available either 
electronically through 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 final 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 of 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.

[[Page 76221]]

 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.
                               v.                    david@epa.gov.
Polymers and Resins, Group    Scott Throwe (202)    Randy McDonald (919)
 II.                           564-7013              541-5402 Mcdonald.
                               throwe.scott@epa.go   randy@epa.gov.
                               v.
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 this final action 
are listed in Table 2 to this preamble.

               Table 2--Eight Industrial Source Categories
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                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.

    Table 2 is not intended to be exhaustive, but rather provides a 
guide for readers regarding entities likely to be affected by the final 
action for the source categories listed. 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.
    Worldwide Web (WWW). In addition to being available in the docket, 
an electronic copy of this final action will also be available on the 
WWW through the Technology Transfer Network (TTN). Following signature, 
a copy of the final action will be posted on the TTN's policy and 
guidance page for newly proposed and promulgated rules at the following 
address: http://www.epa.gov/ttn/oarpg/. The TTN provides information 
and technology exchange in various areas of air pollution control.
    Judicial Review. Under section 307(b)(1) of the Clean Air Act 
(CAA), judicial review of this final action is available only by filing 
a petition for review in the United States Court of Appeals for the 
District of Columbia Circuit within 60 days of publication of this 
action in the Federal Register, i.e., by February 17, 2009. Under 
section 307(b)(2) of the CAA, the requirements established by this 
final action may not be challenged separately in any civil or criminal 
proceedings brought by EPA to enforce the requirements.
    Section 307(d)(7)(B) of the CAA further provides that ``[o]nly an 
objection to a rule or procedure which was raised with reasonable 
specificity during the period for public comment (including any public 
hearing) may be raised during judicial review.'' This section also 
provides that EPA shall convene a proceeding for reconsideration, 
``[i]f the person raising an objection can demonstrate to the 
Administrator that it was impracticable to raise such objection within 
[the period for public comment] or if the grounds for such objection 
arose after the period for public comment (but within the time 
specified for judicial review) and if such objection is of central 
relevance to the outcome of the rule.'' Any person seeking to make such 
a demonstration should submit a Petition for Reconsideration to the 
Office of the Administrator, U.S. EPA, Room 3000, Ariel Rios Building, 
1200 Pennsylvania Ave., NW., Washington, DC 20460, with a copy to both 
the person(s) listed in the preceding FOR FURTHER INFORMATION CONTACT 
section, and the Associate General Counsel for the Air and Radiation 
Law Office, Office of General Counsel (Mail Code 2344A), U.S. EPA, 1200 
Pennsylvania Ave., NW., Washington, DC 20460.
    Outline. The information presented in this preamble is organized as 
follows:

I. Background
    A. What is the statutory authority for this action?
    B. Overview of the Four NESHAP
    C. What was the proposed action?
    D. What are the conclusions of the residual risk assessment?
    E. What are the conclusions of the technology review?
II. Summary of Comments and Responses
    A. Emissions Data
    B. Risk Assessment Methodology
III. Risk and Technology Review Final Decision
IV. 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

[[Page 76222]]

    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 CAA establishes a two-stage regulatory process 
to address emissions of hazardous air pollutants (HAP) from stationary 
sources. In the first stage, after EPA has identified categories of 
sources emitting one or more of the HAP listed in section 112(b) of the 
CAA, section 112(d) of the CAA calls for us to promulgate NESHAP for 
those sources. ``Major sources'' are those that emit or have the 
potential to emit any single HAP at a rate of 10 tons or more per year 
of a single HAP or 25 tons per year of any combination of HAP. For 
major sources, these technology-based standards must reflect the 
maximum degree of emission reductions of HAP achievable (after 
considering cost, energy requirements, and non-air quality health and 
environmental impacts) and are commonly referred to as maximum 
achievable control technology (MACT) standards.
    The MACT ``floor'' is the minimum control level allowed for MACT 
standards promulgated under CAA section 112(d)(3). For new sources, the 
MACT floor cannot be less stringent than the emission control that is 
achieved in practice by the best-controlled similar source. The MACT 
standards for existing sources can be less stringent than standards for 
new sources, but they cannot be less stringent than the average 
emission limitation achieved by the best-performing 12 percent of 
existing sources in the category or subcategory (or the best-performing 
five sources for categories or subcategories with fewer than 30 
sources). In developing MACT standards, we must also consider control 
options that are more stringent than the floor. We may establish 
standards more stringent than the floor based on the consideration of 
the cost of achieving the emissions reductions, any non-air quality 
health and environmental impacts, and energy requirements.
    EPA is then required to review these 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, under CAA section 112(d)(6). In this final rule, we 
are publishing the results of our 8-year technology review for the 
eight industrial source categories listed in Table 3, which we have 
collectively termed ``Group 1.''
    The second stage in standard-setting focuses on reducing any 
remaining ``residual'' risk according to CAA section 112(f). This 
provision requires, first, that EPA prepare a Report to Congress 
discussing (among other things) methods of calculating risk posed (or 
potentially posed) by sources after implementation of the MACT 
standards, the public health significance of those risks, the means and 
costs of controlling them, actual health effects to persons in 
proximity of emitting sources, and recommendations as to legislation 
regarding such remaining risk. EPA prepared and submitted this report 
(Residual Risk Report to Congress, EPA-453/R-99-001) in March 1999. 
Congress did not act in response to the report, thereby triggering 
EPA's obligation under CAA section 112(f)(2) to analyze and address 
residual risk.
    CAA section 112(f)(2) requires us to determine for source 
categories subject to certain CAA section 112(d) standards whether the 
emissions limitations provide an ample margin of safety to protect 
public health. If the MACT standards for HAP ``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,'' EPA must 
promulgate residual risk standards for the source category (or 
subcategory) as necessary to provide an ample margin of safety to 
protect public health. In doing so, EPA may adopt standards equal to 
existing MACT standards (NRDC v. EPA, No. 07-1053, slip op. at 11, 
District of Columbia Circuit, decided June 6, 2008). EPA must also 
adopt more stringent standards, if necessary, to prevent an adverse 
environmental effect,\1\ but must consider cost, energy, safety, and 
other relevant factors in doing so. Section 112(f)(2) of the CAA 
expressly preserves our use of a two-step process for developing 
standards to address any residual risk and our interpretation of 
``ample margin of safety'' developed in the National Emission Standards 
for Hazardous Air Pollutants: Benzene Emissions from Maleic Anhydride 
Plants, Ethylbenzene/Styrene Plants, Benzene Storage Vessels, Benzene 
Equipment Leaks, and Coke By-Product Recovery Plants (Benzene NESHAP) 
(54 FR 38044, September 14, 1989).
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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 anticiipated, to wildlife, aquatic life, or other 
natural resources, including adverse impacts on populations of 
endangered or threatened species or significant degradation of 
environmental quality over broad areas.
---------------------------------------------------------------------------

    The first step in this process is the determination of acceptable 
risk. The second step provides for an ample margin of safety to protect 
public health, which is the level at which the standards are set 
(unless a more stringent standard is required to prevent, taking into 
consideration costs, energy, safety, and other relevant factors, an 
adverse environmental effect).
    The terms ``individual most exposed,'' ``acceptable level,'' and 
``ample margin of safety'' are not specifically defined in the CAA. 
However, CAA section 112(f)(2)(B) directs us to use the interpretation 
set out in the Benzene NESHAP. See also, A Legislative History of the 
Clean Air Act Amendments of 1990, volume 1, p. 877 (Senate debate on 
Conference Report). We notified Congress in the Residual Risk Report to 
Congress that we intended to use the Benzene NESHAP approach in making 
CAA section 112(f) residual risk determinations (EPA-453/R-99-001, p. 
ES-11).
    In the Benzene NESHAP, we stated as an overall objective:

* * * in protecting public health with an ample margin of safety, we 
strive to provide maximum feasible protection against risks to 
health from hazardous air pollutants by (1) protecting the greatest 
number of persons possible to an individual lifetime risk level no 
higher than approximately 1-in-1 million; and (2) limiting to no 
higher than approximately 1-in-10 thousand [i.e. , 100-in-1 million] 
the estimated risk that a person living near a facility would have 
if he or she were exposed to the maximum pollutant concentrations 
for 70 years.

The Agency also stated that, ``The EPA also considers incidence (the 
number of persons estimated to suffer cancer or other serious health 
effects as a result of exposure to a pollutant) to be an important 
measure of the health risk to the exposed population. Incidence 
measures the extent of health risk to the exposed population as a 
whole, by providing an estimate of the occurrence of cancer or other 
serious health effects in the exposed population.'' The Agency went on 
to conclude that ``estimated incidence would be weighed along with 
other health risk information in judging acceptability.'' As explained 
more fully in our Residual Risk Report to Congress, EPA does not define 
``rigid line[s] of acceptability,'' but considers rather broad 
objectives to be weighed with a

[[Page 76223]]

series of other health measures and factors (EPA-453/R-99-001, p. ES-
11). The determination of what represents an ``acceptable'' risk is 
based on a judgment of ``what risks are acceptable in the world in 
which we live'' (Residual Risk Report to Congress, p. 178, quoting the 
Vinyl Chloride decision at 824 F.2d 1165) recognizing that our world is 
not risk-free.
    In the Benzene NESHAP, we stated that ``EPA will generally presume 
that if the risk to [the maximum exposed] individual is no higher than 
approximately 1-in-10 thousand, that risk level is considered 
acceptable.'' 54 FR at 38045. We discussed the maximum individual 
lifetime cancer risk (MIR) as being ``the estimated risk that a person 
living near a plant would have if he or she were exposed to the maximum 
pollutant concentrations for 70 years.'' Id. We explained that this 
measure of risk ``is an estimate of the upperbound of risk based on 
conservative assumptions, such as continuous exposure for 24 hours per 
day for 70 years.'' Id. We acknowledge that MIR ``does not necessarily 
reflect the true risk, but displays a conservative risk level which is 
an upperbound that is unlikely to be exceeded.'' Id.
    Understanding that there are both benefits and limitations to using 
MIR as a metric for determining acceptability, we acknowledged in the 
1989 Benzene NESHAP that ``consideration of maximum individual risk * * 
* must take into account the strengths and weaknesses of this measure 
of risk.'' Id. Consequently, the presumptive risk level of 100-in-1 
million (1-in-10 thousand) provides a benchmark for judging the 
acceptability of MIR, but does not constitute a rigid line for making 
that determination.
    The Agency also explained in the 1989 Benzene NESHAP the following: 
``In establishing a presumption for MIR, rather than rigid line for 
acceptability, the Agency intends to weigh it with a series of other 
health measures and factors. These include the overall incidence of 
cancer or other serious health effects within the exposed population, 
the numbers of persons exposed within each individual lifetime risk 
range and associated incidence within, typically, a 50 kilometer (km) 
exposure radius around facilities, the science policy assumptions and 
estimation uncertainties associated with the risk measures, weight of 
the scientific evidence for human health effects, other quantified or 
unquantified health effects, effects due to co-location of facilities, 
and co-emission of pollutants.'' Id.
    In some cases, these health measures and factors taken together may 
provide a more realistic description of the magnitude of risk in the 
exposed population than that provided by MIR alone.
    As explained in the Benzene NESHAP, ``[e]ven though the risks 
judged ``acceptable'' by EPA in the first step of the Vinyl Chloride 
inquiry are already low, the second step of the inquiry, determining an 
``ample margin of safety,'' again includes consideration of all of the 
health factors, and whether to reduce the risks even further. In the 
second step, EPA strives to provide protection to the greatest number 
of persons possible to an individual lifetime risk level no higher than 
approximately 1-in-1 million. In the ample margin decision, the Agency 
again considers all of the health risk and other health information 
considered in the first step. Beyond that information, additional 
factors relating to the appropriate level of control will also be 
considered, including costs and economic impacts of controls, 
technological feasibility, uncertainties, and any other relevant 
factors. Considering all of these factors, the Agency will establish 
the standard at a level that provides an ample margin of safety to 
protect the public health, as required by section 112.'' 54 FR 38046.

B. Overview of the Four NESHAP

    The eight industrial source categories and four NESHAP that are the 
subject of this action are listed in Table 3 to this preamble. The 
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 This Final Action
----------------------------------------------------------------------------------------------------------------
                                                          Promulgated rule
                                    Source categories    reference and code
         Title of NESHAP             affected by this        of federal        Compliance     NESHAP as referred
                                       final action         regulations           date       to in this preamble
                                                              citation
----------------------------------------------------------------------------------------------------------------
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   40 CFR part 63,
                                    Rubber Production.   subpart U.
                                   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            40 CFR part 63,
                                    Polyamides           subpart SS.
                                    Production.
NESHAP for GMACT \2\.............  Acetal Resins        64 FR 34853 (06/29/      06/29/2002  GMACT.
                                    Production.          1999).
                                   Hydrogen Fluoride    40 CFR part 63,
                                    Production.          subparts TT, UU,
                                                         WW, and YY .
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\1\ The Polymers and Resins I NESHAP regulates nine source categories. We performed the residual risk and
  technology review (RTR) for four of them for this action. We will address the remaining five source categories
  in a separate RTR rulemaking.
\2\ The source categories subject to the standards in the generic maximum achievable control technology (GMACT)
  NESHAP are Acetal Resins Production and Hydrogen Fluoride Production.

1. Polymers and Resins I
    The Polymers and Resins I NESHAP regulates HAP emissions from major 
sources in nine source categories. In this action, we address four of 
the Polymer and Resins I sources categories--Polysulfide Rubber 
Production, Ethylene Propylene Rubber Production, Butyl Rubber 
Production, and Neoprene Production. The other five source categories 
are addressed in RTR Group 2A (73 FR 60432, October 10, 2008). HAP 
emissions from these processes can be released from storage tanks, 
process vents, equipment leaks, and wastewater operations.
    a. Polysulfide Rubber Production. Polysulfide rubber is a synthetic 
rubber

[[Page 76224]]

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.
    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.
    c. Butyl Rubber Production. Butyl rubber is comprised of copolymers 
of isobutylene and isoprene and 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.
    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.
2. Polymers and Resins II
    The Polymers and Resins II NESHAP regulates HAP emissions from 
major sources in two source categories--epoxy resins and non-nylon 
polyamides production. In this action, we address both of the Polymer 
and Resins II sources 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 involves 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.
    b. Non-Nylon Polyamides Production. The Non-Nylon Polyamides 
Production source category involves 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 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.
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.
    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.
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. Hydrogen fluoride is used 
in the production of other compounds, including pharmaceuticals and 
polymers. In aqueous solution hydrogen fluoride can be a strong acid.

C. What was the proposed action?

    On December 12, 2007 \2\, based on the findings from our RTR, we 
proposed no revisions to the four NESHAP regulating the eight source 
categories listed in Table 3 and requested public comment.
---------------------------------------------------------------------------

    \2\ See 72 FR 70543.
---------------------------------------------------------------------------

D. What are the conclusions of the residual risk assessment?

    As required by section 112(f)(2) of the CAA, we prepared a risk 
assessment for each of the eight source categories addressed in this 
action to determine the residual risk posed after implementation of the 
respective NESHAP. To evaluate the residual risk for each source 
category, EPA conducted an inhalation risk assessment \3\ that provided 
estimates of MIR, cancer risk distribution within the exposed 
populations, cancer incidence, hazard indices (HI) 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 (worst case) screening-level analysis and, where the 
screening analysis indicated the potential for non-negligible risks, 
following that with more refined analyses.
---------------------------------------------------------------------------

    \3\ 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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[[Page 76225]]

    The human health risks estimated for the eight source categories 
are summarized in Table 4.

                 Table 4--Summary of Estimated Inhalation Risks for the Eight Source Categories
----------------------------------------------------------------------------------------------------------------
                                                  Maximum
                                                 individual       Estimated
                                              cancer risk (in   annual cancer   Maximum chronic    Maximum off-
                                 Number of     1 million) \2\   incidence (and  HI \3\ (and HAP   site acute HQ
       Source category        facilities \1\      (and HAP           HAP          contributing     and HAP for
                                                contributing     contributing       most to        which HQ was
                                                  most to          most to         estimate)      calculated \4\
                                                 estimate)        estimate)
----------------------------------------------------------------------------------------------------------------
Polysulfide Rubber                         1  0 \6\..........  0 \6\..........  <0.01 (MDI \5\)  HQERPG-1=0.0004
 Production.                                                                                      (MDI \4\).
Ethylene Propylene Rubber                  5  0 \6\..........  0 \6\..........  0.5 (hexane)...  HQREL=0.3
 Production.                                                                                      (toluene).
Butyl Rubber Production.....               2  0 \6\..........  0 \6\..........  0.2 (methyl      HQERPG-2=0.1
                                                                                 chloride).       (methyl
                                                                                                  chloride \7\).
Neoprene Production.........               1  0 \6\..........  0 \6\..........  0.8              HQREL=0.4
                                                                                 (chloroprene).   (toluene).
Epoxy Resins Production.....               3  0.1              0.00002          0.08             HQREL=0.6
                                               (epichlorohydr   (epichlorohydr   (epichlorohydr   (epichlorohydr
                                               in).             in).             in).             in).
Non-nylon Polyamides                       4  0.4              0.00003          0.3              HQREL=0.2
 Production.                                   (epichlorohydr   (epichlorohydr   (epichlorohydr   (epichlorohydr
                                               in).             in).             in).             in).
Acetal Resins Production....               3  0.3 (allyl       0.00004 (allyl   0.2 (chlorine).  HQREL=2 HQAEGL-
                                               chloride).       chloride).                        1=0.1
                                                                                                  (formaldehyde)
                                                                                                  .
Hydrogen Fluoride Production               2  0 \6\..........  0 \6\..........  <0.01            HQREL=0.3
                                                                                 (hydrofluoric    (hydrofluoric
                                                                                 acid).           acid).
----------------------------------------------------------------------------------------------------------------
\1\ Number of facilities believed to be in the source category and used in the risk analysis.
\2\ Maximum 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 reference exposure level (REL) and ERPG-1 and
  ERPG-2 values. The superscript indicates the value to which the acute exposure estimate was compared. The
  acute REL is defined by CalEPA as ``the concentration level at or below which no adverse health effects are
  anticipated for a specified exposure duration is termed the reference exposure level (REL). REL are based on
  the most sensitive, relevant, adverse health effect reported in the medical and toxicological literature. REL
  are designed to protect the most sensitive individuals in the population by the inclusion of margins of
  safety. Since margins of safety are incorporated to address data gaps and uncertainties, exceeding the REL
  does not automatically indicate an adverse health impact.'' The American Industrial Hygiene Association
  defines the ERPG-1 as ``the maximum airborne concentration below which it is believed that nearly all
  individuals could be exposed for up to 1 hour without experiencing other than mild transient adverse health
  effects or without perceiving a clearly defined, objectionable odor'', and the ERPG-2 as ``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.'' The National Advisory Committee for Acute Exposure
  Guidelines defines AEGL-1 as ``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.''
\5\ MDI is methylene diphenyl diisocyanate.
\6\ No HAP that are known, probable, or possible human carcinogens are emitted from sources in the category.
\7\ For methyl chloride, REL, and AEGL-1 were not available.

    As shown in Table 4, we estimate that the HAP emissions from the 
eight source categories affected by this final action 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.
    In addition, no chronic inhalation human health thresholds were 
exceeded at environmental receptors for any of the eight source 
categories. As we stated in the preamble to the proposal, 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. Only hydrogen fluoride among those emitted by these 
facilities has a potential concern for adverse environmental effects, 
based on a consideration of studies in the literature. Accordingly, we 
posed the question in the preamble to the proposal whether hydrogen 
fluoride emissions impacted vegetation in the vicinity of the two 
facilities in the hydrogen fluoride category. No comments were 
received. We have concluded that for all facilities in categories 
addressed in this rulemaking, 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.
    Human health multipathway risks were determined not to be a concern 
for the eight source categories addressed in this action due to the 
absence of persistent and bioaccumulative (PB) \4\ 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).
---------------------------------------------------------------------------

    \4\ 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.
---------------------------------------------------------------------------

    As a result of these findings, we proposed no additional controls 
under the residual risk review requirements of CAA section 112(f)(2). 
As EPA has not received evidence which would alter our proposed 
decision, we conclude in this rulemaking, as proposed, that no 
additional control is required because

[[Page 76226]]

the four NESHAP regulating the eight source categories addressed in 
this action provide an ample margin of safety to protect public health 
and to prevent an adverse environmental effect.

E. What are the conclusions of the technology review?

    Section 112(d)(6) of the CAA requires EPA to review and revise, as 
necessary (taking into account developments in practices, processes, 
and control technologies), emissions standards promulgated under CAA 
section 112 no less often than every 8 years. As we explained in our 
CAA section 112(d)(6) determination for the HON (71 FR 34437 and 
affirmed at 71 FR 76606),

    [a]lthough the language of section 112(d)(6) is nondiscretionary 
regarding periodic review, it grants EPA much discretion to revise 
the standards ``as necessary.'' Thus, although the specifically 
enumerated factors that EPA should consider all relate to technology 
(e.g., developments in practices, processes and control 
technologies), the instruction to revise ``as necessary'' indicates 
that EPA is to exercise its judgment in this regulatory decision, 
and is not precluded from considering additional relevant factors, 
such as costs and risk. EPA has substantial discretion in weighing 
all of the relevant factors in arriving at the best balance of costs 
and emissions reduction and determining what further controls, if 
any, are necessary. This interpretation is consistent with numerous 
rulings by the U.S. Court of Appeals for the DC Circuit regarding 
EPA's approach to weighing similar enumerated factors under 
statutory provisions directing the Agency to issue technology-based 
standards. See, e.g., Husqvarna AB v. EPA, 254 F.3d 195 (DC Cir. 
2001). For example, when a section 112(d)(2) MACT standard alone 
obtains protection of public health with an ample margin of safety 
and prevents adverse environmental effects, it is unlikely that it 
would be ``necessary'' to revise the standard further, regardless of 
possible developments in control options.\5\ Thus, the section 
112(d)(6) review would not need to entail a robust technology 
assessment.
---------------------------------------------------------------------------

    \5\ Although EPA might still consider developments that could 
substantially reduce or eliminate risk in a cost-effective manner.

    We completed the CAA section 112(d)(6) review for the eight RTR 
Group 1 source categories, and, as in our proposal, we concluded that 
there have been no significant developments in practices, processes, or 
control technologies since promulgation of the MACT standards for the 
eight RTR Group 1 source categories. Thus, we proposed no additional 
controls were required under the technology review requirements of CAA 
section 112(d)(6).
    We have not received information that controverts that conclusion. 
Therefore, we conclude, as we did in the proposed rule, that no 
revisions are required per the provisions of CAA section 112(d)(6).

II. Summary of Comments and Responses

    In the proposed action, we requested public comment on our residual 
risk reviews and our technology reviews for the eight source categories 
listed in Table 3. We received comments from four commenters. The 
commenters included one state and local agency association, two 
industry trade associations, and representatives of one individual 
company. The comments are summarized and our responses to adverse 
comments are provided below.\6\ After considering the public comments, 
we concluded it was unnecessary to change our risk or technology 
reviews or analyses or our determination that the existing MACT 
standards for these eight source categories are sufficient under 
sections 112(d)(6) and (f)(2) of the CAA.
---------------------------------------------------------------------------

    \6\ See ``Summary of Public Comments and Responses for RTR Group 
1'' for other comment summaries and responses.
---------------------------------------------------------------------------

A. Emissions Data

    Comment: One commenter expressed concern over the emissions and 
emissions release characteristic data the Agency used in its analyses, 
noting that the proposal did not explain why state and local air agency 
data were not included for source categories where EPA primarily relied 
upon industry-supplied data. The commenter recommends that EPA consider 
expanding the data set to include state and local information. The 
other three commenters believe the data are representative for the RTR 
Group 1 source categories, although one of them suggested EPA should 
discount the value of emissions inventory data that have not undergone 
a quality assurance review.
    Response: For the residual risk assessments, we use the best 
information available to perform our analyses. The EPA collects 
facility-specific emissions and emissions release characteristic 
information from state and local agencies periodically, which is then 
put into a database called the National Emissions Inventory (NEI). This 
information is reviewed by EPA engineers. The information contained in 
this database is often the best source of information available to us 
and it typically provides the essential parameters for our residual 
risk analyses. However, there are limitations to this database, in that 
the quality of the data submitted by state and local air agencies 
varies. Some parameters in the NEI are not provided by all state and 
local air agencies, which means that these parameters are sometimes 
blank or are filled in with default values. In addition, if process or 
other changes occur at facilities that do not affect their permits, 
state or local air agencies may not be aware of these changes, and 
subsequently do not submit changes or updates to the emissions for 
those facilities.
    To analyze risk for these eight source categories, we were able to 
use emissions and emissions release characteristic data obtained 
directly from industry except for the hydrogen fluoride source category 
for which the data were obtained directly from industry and from the 
State of Louisiana. Based on our own technical review of these data, we 
believe these data are the most accurate data available, and where 
available, we used them for our analyses. All of the emissions and 
emissions release characteristic data were made available for public 
review at the time of the proposal. State and local air agencies, as 
well as other members of the public, were invited to provide comments 
on the data. We would have considered any substantive comments 
regarding the accuracy of the data before promulgating today's decision 
not to require new or additional standards; however, other than the 
data from Louisiana and one minor comment, addressed below, no such 
comments were received from any of the state or local air agencies, or 
from any other commenter. Therefore, no significant changes to the data 
have been made.
    On June 6, 2008, the United States Court of Appeals for the 
District of Columbia (the Court) upheld as reasonable EPA's use of 
industry data, in that case, where EPA demonstrated that such data 
enabled the Agency to assess risk remaining after application of the 
National Emission Standards for Organic Hazardous Air Pollutants From 
the Synthetic Organic Chemical Manufacturing Industry (HON) \7\, and 
noted that ``EPA has wide latitude in determining the extent of data-
gathering necessary to solve a problem.'' \8\
---------------------------------------------------------------------------

    \7\ Proposed and final National Emission Standards for Organic 
Hazardous Air Pollutants from the Synthetic Organic Chemical 
Manufacturing Industry (HON) residual risk rules (71 FR 34421, June 
14, 2006, and 71 FR 76603, December 21, 2006, respectively).
    \8\ See page 17 of the Court Opinion. The Court's opinion was 
issued in response to petition received on the final HON RTR. The 
Court's opinion, the proposal and final HON RTR rules, and EPA's 
Brief for the Respondent are in the RTR Group 1 docket (Docket ID 
No. EPA-HQ-OAR-2007-0211).
---------------------------------------------------------------------------

    Comment: One commenter recommended that EPA include emissions from 
startup/shutdown and

[[Page 76227]]

malfunctions (SSM) in its analysis, as they are the cause of 
significant HAP emissions and not including them underestimates true 
risks.
    Response: Emission releases from SSM events are typically 
infrequent and of short duration compared to annual emissions. Startup 
and shutdown events \9\ usually coincide with routine equipment 
maintenance or upset conditions, or with an initial startup of a 
process. Malfunction events are sudden and infrequent and must be 
corrected as soon as practicable after their occurrence. 40 CFR 
63.6(e), which generally applies to all MACT rules in part 63, requires 
the owner or operator of a facility to reduce emissions from the 
affected source during periods of SSM to the greatest extent which is 
consistent with safety and good air pollution control practices.
---------------------------------------------------------------------------

    \9\ All three terms are defined in 40 CFR 63.2. ``Malfunction'' 
means any sudden, infrequent, and not reasonably preventable failure 
of air pollution control and monitoring equipment, process 
equipment, or a process to operate in a normal or usual manner which 
causes, or has the potential to cause, the emission limitations in 
an applicable standard to be exceeded. Failures that are caused, in 
part, by poor maintenance or careless operation are not 
malfunctions. ``Shutdown'' means the cessation of operation of an 
affected source or portion of an affected source for any purpose. 
``Startup'' means the setting in operation of an affected source or 
portion of an affected source for any purpose. And from the 2002 
General Provisions for 40 CFR Part 63 BID for Promulgated Amendments 
[EPA-453/R-02-002], ``shutdown'' specifically means only the process 
of shutting off equipment or a process, and does not refer to the 
period of non-operation. Thus, during this period when a process is 
offline or between production runs, the source must meet the 
standard, including emission limits, as well as monitoring, 
recordkeeping, and reporting requirements.
---------------------------------------------------------------------------

    We believe SSM events do not contribute significantly to cancer or 
chronic noncancer risks for the RTR Group 1 source categories because 
SSM events are inherently short-term and infrequent relative to annual 
operations and emissions. The commenter did not supply data. In 
addition, cancer and chronic noncancer risk for the RTR Group 1 source 
categories are low. All the RTR Group 1 source categories have a MIR 
less than 1-in-1 million and an HI less than 1: emissions from SSM 
events would have to be greater than double the annual emission levels 
to result in MIR greater than 1-in-1 million or HI greater than 1, and 
this is improbable.
    To better assess SSM emissions, we analyzed SSM emissions of HAP 
from all major industries (primarily petroleum refineries and chemical 
manufacturers) in five counties in southeast Texas.\10\ Our analysis of 
these data indicates that multiplying the annual average hourly 
emission rate by a factor of 10 to estimate the worst-case hourly 
emission rate would account for 99 percent of the reported SSM emission 
rates. As a result, we apply this default factor of 10 to screen for 
potential acute impacts of concern for all RTR source categories. In 
this case, use of this factor screened out potential acute impacts from 
all RTR Group 1 source categories except for a few facilities from the 
Acetal Resins Production and Hydrogen Fluoride Production source 
categories.
---------------------------------------------------------------------------

    \10\ Our analysis of the SSM data on upset emissions (reported 
over an 11 month period in 2001) from the Houston, Texas area showed 
that SSM emissions for facilities in this area typically total 
significantly less than 15 percent of annual routine emissions, 
thereby minimizing their potential to increase chronic health risks 
to any significant degree. See Appendix 4 to ``Residual Risk 
Assessment for Eight Source Categories: Polysulfide Rubber 
Production, Ethylene Propylene Rubber Production, Butyl Rubber 
Production, Neoprene Production, Epoxy Resins Production, Non-nylon 
Polyamides Production, Hydrogen Fluoride Production, Acetal Resins 
Production'' (July 2008), which is available in the RTR Group 1 
docket.
---------------------------------------------------------------------------

    For acetal resins production and hydrogen fluoride production, we 
applied a source category-specific factor of 2 times the average hourly 
rate for hydrogen fluoride production and 1.5 times the average hourly 
rate for acetal resins production to estimate the worst-case hourly 
emission rate. These factors are derived from industry data and one 
state that show the peak hourly emissions that have been recorded. 
Applying these multipliers to our screening scenario eliminated concern 
for the Hydrogen Fluoride Production source category and reduced the 
estimated maximum projected acute impact of 1-hour formaldehyde 
concentrations at any acetal resins production facility to 
approximately twice the reference exposure level (HQREL=2), 
and approximately one-tenth the Acute Exposure Guideline Level 
(HQAEGL-1=0.1). The REL is a ``concentration level at or 
below which no adverse health effects are anticipated for a specified 
exposure duration,'' and ``exceeding the REL does not automatically 
indicate an adverse health impact.'' Furthermore, we believe that the 
likelihood of worst-case meteorological conditions occurring at the 
same time as a significant upset event and at the location where human 
exposure is the greatest is improbable. Therefore, considering the 
value of the maximum HQ along with the improbability of the convergence 
of worst-case SSM emissions (which we believe to be infrequent events), 
worst-case meteorological conditions and worst-case human exposure, we 
determined that this outcome did not warrant cause for concern.
    Comment: One commenter noted that they had provided minor updates 
to emissions and modeling parameters for three facilities on November 
19, 2004, and again in the fall of 2007, but noticed that these updates 
were not included in the documentation. The commenter noted that the 
updates will have no effect on the cancer MIR modeling and only a minor 
impact on the HI, and requested that EPA use the updated information if 
it determines additional modeling runs are necessary.
    Response: We regret this error and have incorporated these changes 
into the datasets for these source categories. As these changes were 
very minor, we did not re-model with the updated versions of the data, 
as a review of the updated data showed that the risk results would not 
be affected to any appreciable degree.
    Comment: We received comment both in favor of and objecting to the 
use of reported ``actual'' emissions in our analyses. The commenters in 
favor of this approach felt actual emissions provide more realistic 
estimates of risk. In contrast, one commenter thought actual emissions 
and associated impacts could increase over time, and analyses based on 
these emissions underestimate residual risk and are inconsistent with 
the applicability sections of the MACT standards.
    Response: We have discussed the use of both MACT allowable 
emissions and actual emissions in previous actions, including the final 
National Emission Standards for Coke Oven Batteries residual risk rule 
and the proposed and final HON residual risk rules.\11\ In those 
previous actions, we noted that modeling the MACT allowable levels of 
emissions (i.e., the highest emission levels that could be emitted 
while still complying with the NESHAP 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 risk analysis, in accordance with the 
Benzene NESHAP. We recognize that facilities strive to achieve greater 
emissions reductions than required by MACT to allow for process 
variability and to prevent exceedances of standards due to emissions 
increases on individual days. Thus, failure to consider actual 
emissions estimates in

[[Page 76228]]

risk assessments could unrealistically inflate estimated risk levels 
because actual emissions estimates represent the typical practices of a 
facility.
---------------------------------------------------------------------------

    \11\ See final National Emission Standards for Coke Oven 
Batteries residual risk rule (70 FR 19998-19999, April 15, 2005) and 
the proposed and final HON residual risk rules (71 FR 34428, June 
14, 2006, and 71 FR 76603, December 21, 2006, respectively.
---------------------------------------------------------------------------

    We followed this approach for our analysis for the eight source 
categories. As explained in the preamble to the proposed rule, we 
evaluated whether allowable emissions would significantly vary from 
actual emissions. We concluded that actual emissions approximated 
allowable levels for all eight source categories and, thus, were 
sufficient for our review. 72 FR 70549-50. We received no comments that 
suggested or provided data indicating that actual emissions do not 
approximate the allowable levels for these eight source categories.

B. Risk Assessment Methodology

    Comment: Comments were received arguing that the Agency's proposed 
quantified risks are over-estimated due to the conservative approach 
used in predicting risks, which included the use of upper bound unit 
risk estimates (URE) for cancer and a 70-year exposure assumption.
    Response: We acknowledge that the use of upper bound URE and 70-
year exposure duration are sources of uncertainty in our analyses that 
tend to overestimate risk. In general, EPA considers the URE to be an 
upper bound estimate based on the method of extrapolation, meaning it 
represents a plausible upper limit to the true value. The true risk is, 
therefore, likely to be less, though it could be greater, and could be 
as low as zero. With regard to exposure duration, we acknowledge that 
we did not address long-term population mobility (residence time or 
exposure duration) in this assessment or population growth or decline 
over 70 years, instead basing our assessment on the assumption that 
each person's predicted exposure is constant over the course of a 70-
year lifetime.
    As explained in our risk assessment, three metrics are generally 
estimated in assessing cancer risk: the MIR, the population risk 
distribution, and the cancer incidence. Our failure to consider short- 
or long-term population mobility does not bias our estimate of the 
theoretical MIR. (Note that the Benzene NESHAP states that the MIR 
``does not necessarily reflect the true risk, but displays a 
conservative risk level which is an upperbound that is unlikely to be 
exceeded.'' \12\) Our estimates of cancer incidence also are not 
influenced by our population mobility assumptions, although 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 United States facilities), will influence the cancer 
incidence associated with a given source category.
---------------------------------------------------------------------------

    \12\ National Emission Standards for Hazardous Air Pollutants: 
Benzene Emissions from Maleic Anhydride Plants, Ethylbenzene/Styrene 
Plants, Benzene Storage Vessels, Benzene Equipment Leaks, and Coke 
By-Product Recovery Plants (Benzene NESHAP) (54 FR 38045, September 
14, 1989).
---------------------------------------------------------------------------

    Our population mobility (residence time or exposure duration) 
assumption does, however, affect the shape of the distribution of 
individual risks across the affected population, shifting it toward 
higher estimated individual risks at the upper end and reducing the 
number of people estimated to be at lower risks, thereby biasing the 
risk estimates high.
    While the approach we use for our screening analysis is 
conservative, we note that where our screening analysis indicates a 
potential for risk, we then perform additional, more refined analyses 
that more closely approximate the true risk from sources that do not 
``screen-out.''
    Comment: We received comments both in favor of and objecting to the 
use of census block centroids in the analysis of chronic exposure and 
risk. One commenter argued that the use of the census block centroid 
dilutes the effect of sources' emissions, as the maximum point of 
impact can be far from the centroid and may be at or near a facility's 
property line, and suggested that the risks for a source category be 
based on concentrations at the fenceline and beyond and include risks 
to the maximally exposed individual. In contrast, other commenters felt 
the use of the census block centroids was appropriate for these source 
categories, and one commenter added that using the fenceline as a 
location to estimate risk is inappropriate in risk assessment because 
people do not generally live at the fenceline, and this approach would 
overstate risk.
    Response: As we have noted in the development of previous residual 
risk rulemakings, such as the HON, EPA contends that, in a national-
scale assessment of lifetime (chronic) inhalation exposures and health 
risks from facilities in a source category, it is appropriate to 
identify exposure locations where it may be reasonably expected that an 
individual will spend a majority of his or her lifetime, such as a 
census block centroid. Thus, EPA asserts that it is appropriate to use 
census block information where people actually reside rather than 
points on a fence-line, to estimate exposure and risk to individuals 
living near such facilities when assessing chronic risks. Census blocks 
are the finest resolution available in the nationwide population data 
(as developed by the United States Census Bureau); each is typically 
comprised of approximately 40 people or about 10 households. In EPA 
risk assessments, the geographic centroid of each census block 
containing at least one person is used to represent the location where 
all the people in that census block live. The census block centroid 
with the highest estimated exposure then becomes the location of 
maximum exposure, and the entire population of that census block 
experiences the maximum individual risk. In some cases, because actual 
residence locations may be closer to or farther from facility emission 
points than is the census block centroid, this may result in an 
overestimate or underestimate of the actual annual exposure. Given the 
relatively small dimensions of census blocks in densely-populated 
areas, there is little uncertainty introduced by using the census block 
centroids. There is more uncertainty when census blocks are larger. 
Recently, EPA used aerial photographs of several facilities to examine 
the locations of census block centroids and actual residences, and to 
assess the impact on maximum individual risk of using the census block 
centroid.\13\ In cases where census blocks were small, there was no 
significant difference in estimated risk. In cases where the census 
blocks were relatively large, the centroid generally was found to be 
nearer the facility than the residential locations. Consequently, the 
risks at the census block centroid typically were higher than the risks 
at any actual residence. In most of these cases, the census block 
contained a portion of the facility property, thereby almost 
necessitating that actual residences be more distant than the block 
centroid. This result indicates that, if anything, using census block 
centroids is more likely to overestimate actual maximum individual 
risks than to underestimate them, although the differences are 
generally small. EPA believes it is appropriate to estimate chronic 
exposures and risks based on census block centroids because: (1) Census 
blocks are the finest resolution available in the national census data, 
(2) facility fencelines do not typically

[[Page 76229]]

represent locations where chronic exposures are likely, and (3) any 
bias introduced by using census block centroids may overestimate 
maximum individual risks.
---------------------------------------------------------------------------

    \13\ See ``Sensitivity analysis of uncertainty in risk estimates 
resulting from estimating exposures at census block centroids near 
industrial facilities'' in RTR Group 1 docket.
---------------------------------------------------------------------------

III. Risk and Technology Review Final Decision

    This final rule responds to public comments received on the 
proposed rule and announces our final decision not to revise the 
standards of the four NESHAP as they apply to the eight RTR Group 1 
source categories. We conclude that the NESHAP applicable to each of 
the eight source categories evaluated in RTR Group 1-- Polysulfide 
Rubber Production, Ethylene Propylene Rubber Production, Butyl Rubber 
Production, Neoprene Production, Epoxy Resins Production, Non-Nylon 
Polyamides Production, Acetal Resins Production, and Hydrogen Fluoride 
Production--provides an ample margin of safety to protect public health 
and prevents adverse environmental effects. Therefore, we are re-
adopting each of the four RTR Group 1 MACT standards for purposes of 
meeting the requirements of CAA section 112(f)(2). In addition, we 
conclude that there have been no developments in practices, processes, 
or control technologies that support revision of the four MACT 
standards pursuant to CAA section 112(d)(6) for the eight source 
categories.

IV. 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 
documented in the docket for this action.

B. Paperwork Reduction Act

    This action does not impose any new information collection burden. 
This action makes no changes to the existing regulations affecting the 
eight source categories included in this final action and will impose 
no additional information collection burden.

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 this 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 (SBA) regulations at 13 CFR 121.201); (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 owned and operated and is not 
dominant in its field.
    After considering the economic impacts of this action on small 
entities, I certify that this action will not have a significant 
economic impact on a substantial number of small entities. This final 
decision does not impose any requirements on small entities.

D. Unfunded Mandates Reform Act

    This action contains no Federal mandates under the provisions of 
Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), 2 U.S.C. 
1531-1538 for state, local, and tribal governments or the private 
sector. The action imposes no enforceable duty on any state, local, or 
tribal governments or the private sector. Therefore, this action is not 
subject to the requirements of sections 202 or 205 of the UMRA.
    This action is also not subject to the requirements of section 203 
of UMRA because it contains no regulatory requirements that might 
significantly or uniquely affect small governments. This action makes 
no changes to the existing regulations affecting the eight source 
categories included in this final action; and, therefore, 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 final decision 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 action.

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

    This action does not have tribal implications, as specified in 
Executive Order 13175 (65 FR 67249, November 9, 2000). 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 action.

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

    This action is not subject to Executive Order 13045 (62 FR 19885, 
April 23, 1997) because it is not economically significant as defined 
in Executive Order 12866, and because the Agency does not believe the 
environmental health or safety risks addressed by this action present a 
disproportionate risk to children. Discussion of this action's health 
and risk assessments are contained in Section I of this preamble.

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

    This final decision 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 
final decision 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.

[[Page 76230]]

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. NTTAA directs EPA to provide Congress, through 
OMB, explanations when the Agency decides not to use available and 
applicable VCS.
    This action does not involve technical standards. Therefore, EPA 
did not consider the use of any VCS.

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 final 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 rule would not relax the control measures on sources 
regulated by the rule and, therefore, would not cause emissions 
increases from these sources.

K. Congressional Review Act

    The Congressional Review Act, 5 U.S.C. 801, et seq., as added by 
the Small Business Regulatory Enforcement Fairness Act of 1996, 
generally provides that before a rule may take effect, the agency 
promulgating the rule must submit a rule report, which includes a copy 
of the rule, to each House of the Congress and to the Comptroller 
General of the United States. EPA will submit a report containing these 
final rules and other required information to the United States Senate, 
the United States House of Representatives, and the Comptroller General 
of the United States prior to publication of the final rules in the 
Federal Register. A major rule cannot take effect until 60 days after 
it is published in the Federal Register . This action is not a ``major 
rule'' as defined by 5 U.S.C. 804(2). This final rule will be effective 
on December 16, 2008.

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 10, 2008.
Stephen L. Johnson,
Administrator.
[FR Doc. E8-29789 Filed 12-15-08; 8:45 am]

BILLING CODE 6560-50-P