National Emission Standards for Hazardous Air Pollutant Emissions: Hard and Decorative Chromium Electroplating and Chromium Anodizing Tanks; Group I Polymers and Resins; Marine Tank Vessel Loading Operations; Pharmaceuticals Production; The Printing and Publishing Industry; and Steel Pickling-HCl Process Facilities and Hydrochloric Acid Regeneration Plants

Federal RegisterOct 21, 2010

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Text

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[EPA-HQ-OAR-2010-0600; FRL-9203-7]

RIN 2060-AO91

National Emission Standards for Hazardous Air Pollutant Emissions: Hard and Decorative Chromium Electroplating and Chromium Anodizing Tanks; Group I Polymers and Resins; Marine Tank Vessel Loading Operations; Pharmaceuticals Production; The Printing and Publishing Industry; and Steel Pickling—HCl Process Facilities and Hydrochloric Acid Regeneration Plants

AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Proposed rule; and supplemental notice of proposed rulemaking.

SUMMARY:

This action proposes how EPA will address the residual risk and technology reviews conducted for two national emission standards for hazardous air pollutants (NESHAP), and this action is a supplemental notice of proposed rulemaking for an October 2008 action that proposed how EPA would address the residual risk and technology reviews for four NESHAP. The six NESHAP include 16 source categories, 12 of which are the subject of residual risk and technology reviews in this package. This action proposes to modify the existing emissions standards for eight source categories in three of the six NESHAP to address certain emission sources not currently regulated under these standards. It also proposes for all six NESHAP to address provisions related to emissions during periods of startup, shutdown, and malfunction. Finally, this action proposes changes to two of the six NESHAP to correct editorial errors, make clarifications, or address issues with implementation or determining compliance.

DATES:

Comments.

Comments must be received on or before December 6, 2010. Under the Paperwork Reduction Act, comments on the information collection provisions are best assured of having full effect if the Office of Management and Budget (OMB) receives a copy of your comments on or before November 22, 2010.

Public Hearing.

We will hold a public hearing on November 5, 2010. Persons requesting to speak at the public hearing must contact EPA by November 1, 2010.

ADDRESSES:

Comments.

Submit your comments, identified by Docket ID No. EPA-HQ-OAR-2010-0600, by one of the following methods:

•

http://www.regulations.gov:

Follow the on-line instructions for submitting comments.

•

E-mail: a-and-r-docket@epa.gov.

Attention Docket ID No. EPA-HQ-OAR-2010-0600.

•

Fax:

(202) 566-9744. Attention Docket ID No. EPA-HQ-OAR-2010-0600.

•

Mail:

U.S. Postal Service, send comments to: EPA Docket Center, EPA West (Air Docket), Attention Docket ID No. EPA-HQ-OAR-2010-0600, U.S. Environmental Protection Agency, Mailcode: 2822T, 1200 Pennsylvania Ave., NW., Washington, DC 20460. Please include a total of two copies. In addition, please mail a copy of your comments on the information collection provisions to the Office of Information and Regulatory Affairs, Office of Management and Budget (OMB), Attn: Desk Officer for EPA, 725 17th Street, NW., Washington, DC 20503.

•

Hand Delivery:

U.S. Environmental Protection Agency, EPA West (Air Docket), Room 3334, 1301 Constitution Ave., NW., Washington, DC 20004. Attention Docket ID No. EPA-HQ-OAR-2010-0600. Such deliveries are only accepted during the Docket's normal hours of operation, and special arrangements should be made for deliveries of boxed information.

Instructions.

Direct your comments to Docket ID No. EPA-HQ-OAR-2010-0600. EPA's policy is that all comments received will be included in the public docket without change and may be made available online at

http://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

http://www.regulations.gov

or e-mail. The

http://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

http://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

http://www.epa.gov/epahome/dockets.htm.

Docket.

The EPA has established a docket for this rulemaking under Docket ID No. EPA-HQ-OAR-2010-0600. All documents in the docket are listed in the

http://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, is not placed on the Internet and will be publicly available only in hard copy. Publicly available docket materials are available either electronically in

http://www.regulations.gov

or in hard copy at the EPA Docket Center, EPA West, Room 3334, 1301 Constitution Ave., 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.

Public Hearing.

We will hold a public hearing concerning this proposed rule on November 5, 2010, from 9 a.m. to 7 p.m. Persons interested in presenting oral testimony at the hearing should contact Ms. Mary Tom Kissell, Sector Policies and Programs Division (E143-01), Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, telephone number, (919) 541-4516, by November 1, 2010. The public hearing will be held at the U.S. Environmental Protection Agency—Research Triangle Park Campus, 109 T.W. Alexander Drive, Research Triangle Park, NC 27709. If no one requests to speak at the public hearing by November 1, 2010, then the public hearing will be cancelled and a notification of cancellation posted on the following Web site:

http://www.epa.gov/ttn/oarpg/t3main.html.

FOR FURTHER INFORMATION CONTACT:

For questions about this proposed action, contact Ms. Mary Tom Kissell, Sector Policies and Programs Division (E143-01), Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, telephone (919) 541-

4516; fax number: (919) 541-0246; and e-mail address:

kissell.mary@epa.gov.

For specific information regarding the risk modeling methodology, contact Ms. Elaine Manning, Health and Environmental Impacts Division (C539-02), Office of Air Quality Planning and Standards, 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 six NESHAP to a particular entity, contact the appropriate person listed in Table 1 to this preamble.

SUPPLEMENTARY INFORMATION:

Table 1—List of EPA Contacts for the NESHAP Addressed in This Proposed Action

NESHAP for:

OECA contact

OAQPS contact

Hard and Decorative Chromium Electroplating and Chromium Anodizing Tanks

Scott Throwe, (202) 564-7013,

throwe.scott@epa.gov

Phil Mulrine, (919) 541-5289,

mulrine.phil@epa.gov

Group I Polymers and Resins Production

Scott Throwe, (202) 564-7013,

throwe.scott@epa.gov

Randy McDonald, (919) 541-5402,

mcdonald.randy@epa.gov

Marine Vessel Loading Operations

Maria Malave, (202) 564-7027,

malave.maria@epa.gov

Steve Shedd, (919) 541-5397,

shedd.steve@epa.gov

Pharmaceuticals Production

Marcia Mia, (202) 564-7042,

mia.marcia@epa.gov

Randy McDonald, (919) 541-5402,

mcdonald.randy@epa.gov

Printing and Publishing Industry

Len Lazarus, (202) 564-6369,

lazarus.leonard@epa.gov

David Salman, (919) 541-0859,

salman.dave@epa.gov

Steel Pickling—HCl Process Facilities and Hydrochloric Acid Regeneration Plants

Maria Malave, (202) 564-7027,

malave.maria@epa.gov

Phil Mulrine, (919) 541-5289,

mulrine.phil@epa.gov

OECA stands for EPA's Office of Enforcement and Compliance Assurance.

OAQPS stands for EPA's Office of Air Quality Planning and Standards.

I. Preamble Acronyms and Abbreviations

Several acronyms and terms used to describe industrial processes, data inventories, and risk modeling are included in this preamble. While this may not be an exhaustive list, to ease the reading of this preamble and for reference purposes, the following terms and acronyms are defined here:

AERMOD—The air dispersion model used by the HEM-3 model

AEGL—Acute Exposure Guideline Levels

ANPRM—Advance Notice of Proposed Rulemaking

ASTM—An international standards organization that develops and publishes voluntary consensus technical standards

ATCM—Airborne Toxics Control Measure

ATSDR—Agency for Toxic Substances and Disease Registry

BACT—Best Available Control Technology

bbl/yr—Barrels per Year

BID—Background Information Document

CalEPA—California Environmental Protection Agency

CARB—California Air Resources Board

CAA—Clean Air Act

CBI—Confidential Business Information

CEEL—Community Emergency Exposure Levels

CIIT—Chemical Industry Institute of Toxicology

CFR—Code of Federal Regulations

CMP—Composite Mesh Pad

CO—Carbon Monoxide

—Carbon Dioxide

D/F—Dioxin/Furan

EED—Emission Elimination Device

EPA—Environmental Protection Agency

EPS—Eco Pickled Surface

ERPG—Emergency Response Planning Guidelines

HAP—Hazardous Air Pollutants

HCl—Hydrochloric Acid

HI—Hazard Index

HEM-3—Human Exposure Model version 3

HEPA—High Efficiency Particulate Air

HON—Hazardous Organic National Emissions Standards for Hazardous Air Pollutants

HQ—Hazard Quotient

ICR—Information Collection Request

IRIS—Integrated Risk Information System

Km—Kilometer

LAER—Lowest Achievable Emission Rate

MACT—Maximum Achievable Control Technology

MACT Code—A code within the NEI used to identify processes included in a source category

mg/dscm—Milligrams per Dry Standard Cubic Meter

MIR—Maximum Individual Risk

MTVLO—Marine Tank Vessel Loading Operations

NAC/AEGL Committee—National Advisory Committee for Acute Exposure Guideline Levels for Hazardous Substances

NAICS—North American Industry Classification System

NAS—National Academy of Sciences

NATA—National Air Toxics Assessment

NESHAP—National Emissions Standards for Hazardous Air Pollutants

NEI—National Emissions Inventory

—Nitrogen Oxide

NRC—National Research Council

NSR—New Source Review

NTTAA—National Technology Transfer and Advancement Act

OECA—Office of Enforcement and Compliance Assurance

OLD—Organic Liquids Distribution

OMB—Office of Management and Budget

PB-HAP—Hazardous air pollutants known to be persistent and bio-accumulative in the environment

PFC—Perfluorinated Chemical

PFOS—Perfluorooctyl Sulfonate

PM—Particulate Matter

POM—Polycyclic Organic Matter

RACT—Reasonably Available Control Technology

RBLC—RACT/BACT/LAER Clearinghouse

REL—CalEPA Chronic Reference Exposure Level

RFA—Regulatory Flexibility Act

RfC—Reference Concentration

RfD—Reference Dose

RTR—Residual Risk and Technology Review

SAB—Science Advisory Board

SCC—Source Classification Codes

SCS—Smooth Clean Surface

SF3—2000 Census of Population and Housing Summary File 3

—Sulfur Dioxide

SOP—Standard Operating Procedures

SSM—Startup, Shutdown, and Malfunction

TOSHI—Target Organ-Specific Hazard Index

TPY—Tons Per Year

TRIM—Total Risk Integrated Modeling System

TTN—Technology Transfer Network

UF—Uncertainty Factor

UMRA—Unfunded Mandates Reform Act

URE—Unit Risk Estimate

VOC—Volatile Organic Compounds

WAFS—Wetting Agent/Fume Suppressant

WCSC—Waterborne Commerce Statistics Center

WWW—Worldwide Web

II. General Information

A. Does this action apply to me?

The regulated industrial source categories that are the subject of this 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 action. The

regulated categories affected by this proposed action include:

Table 2—NESHAP and Industrial Source Categories Affected by This Proposed Action

NESHAP and source category

NAICS code

MACT code

Chromium Electroplating

Chromium Anodizing Tanks

332813

1607

Decorative Chromium Electroplating

332813

1610

Hard Chromium Electroplating

332813

1615

Group I Polymers and Resins

Butyl Rubber Production

325212

1307

Epichlorohydrin Elastomers Production

325212

1311

Ethylene Propylene Rubber Production

325212

1313

Hypalon

Production

325212

1315

Neoprene Production

325212

1320

Nitrile Butadiene Rubber Production

325212

1321

Polybutadiene Rubber Production

325212

1325

Polysulfide Rubber Production

325212

1332

Styrene Butadiene Rubber and Latex Production

325212

1339

Marine Vessel Loading Operations

4883

0603

Pharmaceuticals Production

3254

1201

Printing and Publishing Industry

32311

0714

Steel Pickling—HCl Process Facilities and Hydrochloric Acid Regeneration Plants

3311, 3312

0310

North American Industry Classification System.

Maximum Achievable Control Technology.

There are no longer any operating facilities in either the Hypalon

or Polysulfide Rubber source categories. Therefore, this proposal does not address these source categories.

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

In addition to being available in the docket, an electronic copy of this proposal will also be available on the World Wide Web (WWW) through the Technology Transfer Network (TTN). Following signature by the EPA Administrator, a copy of this proposed action will be posted on the TTN's policy and guidance page for newly proposed or promulgated rules at the following address:

http://www.epa.gov/ttn/atw/rrisk/rtrpg.html.

The TTN provides information and technology exchange in various areas of air pollution control.

Additional information is available on the residual risk and technology review (RTR) Web page at

http://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.

C. What should I consider as I prepare my comments for EPA?

Submitting CBI.

Do not submit information containing CBI to EPA through

http://www.regulations.gov

or e-mail. 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 EPA, 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 disk 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. Information marked as CBI will not be disclosed except in accordance with procedures set forth in 40 CFR part 2. Send or deliver information identified as CBI only to the following address: Roberto Morales, OAQPS Document Control Officer (C404-02), Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, Attention Docket ID No. EPA-HQ-OAR-2010-0600.

D. How is this document organized?

The information in this preamble is organized as follows:

I. Preamble Acronyms and Abbreviations

II. General Information

A. Does this action apply to me?

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

C. What should I consider as I prepare my comments for EPA?

D. How is this document organized?

III. Background

A. What is the statutory authority for this action?

B. How did we consider the risk results in making decisions for this proposal?

C. What other actions are we addressing in this proposal?

D. What specific RTR actions have previously been taken for these source categories?

IV. Analyses Performed

A. How did we estimate risk posed by the source categories?

B. How did we perform the technology review?

C. How did we perform the analyses for the other actions being proposed?

V. Analyses Results and Proposed Decisions

A. What are the results and proposed decisions for the Chromium Electroplating source categories?

B. What are the results and proposed decisions for the Group I Polymers and Resins Production source categories?

C. What are the results and proposed decisions for Marine Tank Vessel Loading Operations source category?

D. What are the results and proposed decisions for the Pharmaceuticals Production source category?

E. What are the results and proposed decisions for the Printing and Publishing Industry source category?

F. What are the results and proposed decisions for Steel Pickling-HCl Process

Facilities and Hydrochloric Acid Regeneration Plants source category?

VI. Summary of Proposed Actions

A. What actions are we proposing as a result of the technology reviews?

B. What actions are we proposing as a result of the residual risk reviews?

C. What other actions are we proposing?

VII. Request for Comments

VIII. Submitting Data Corrections

IX. 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

III. Background

A. What is the statutory authority for this action?

Section 112 of the Clean Air Act (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 per year (TPY) or more of a single HAP or 25 TPY or more 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.

MACT standards are to reflect application of measures, processes, methods, systems, or techniques, including, but not limited to, measures which, (A) reduce the volume of or eliminate pollutants through process changes, substitution of materials or other modifications, (B) enclose systems or processes to eliminate emissions, (C) capture or treat pollutants when released from a process, stack, storage, or fugitive emissions point, (D) are design, equipment, work practice, or operational standards (including requirements for operator training or certification), or (E) are a combination of the above. CAA section 112(d)(2)(A)-(E). The MACT standard may take the form of a design, equipment, work practice, or operational standard where EPA first determines either that (A) a pollutant cannot be emitted through a conveyance designed and constructed to emit or capture the pollutant, or that any requirement for or use of such a conveyance would be inconsistent with law, or (B) the application of measurement methodology to a particular class of sources is not practicable due to technological and economic limitations. CAA sections 112(h)(1)-(2).

The MACT “floor” is the minimum control level allowed for MACT standards promulgated under CAA section 112(d)(3), and may not be based on cost considerations. 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 floors for existing sources can be less stringent than floors 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.

The 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 conducting this review, EPA is not obliged to completely recalculate the prior MACT determination.

NRDC

EPA,

529 F.3d 1077, 1084 (District of Columbia Circuit, 2008).

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, the actual health effects to persons in proximity of emitting sources, and the recommendations regarding legislation of 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 MACT standards, whether the emissions standards 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 if EPA determines that the existing standards are sufficiently protective.

NRDC

EPA,

529 F.3d 1077, 1083 (District of Columbia Circuit, 2008). (“If EPA determines that the existing technology-based standards provide an `ample margin of safety,' then the Agency is free to readopt those standards during the residual risk rulemaking.”) EPA must also adopt more stringent standards, if necessary, to prevent an adverse environmental effect,

but must consider cost, energy, safety, and other relevant factors in doing so.

“Adverse environmental effect” is defined in CAA section 112(a)(7) as any significant and widespread adverse effect, which may be reasonably anticipated to wildlife, aquatic life, or natural resources, including adverse impacts on populations of endangered or threatened species or significant degradation of environmental qualities over broad areas.

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). 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) preserves the interpretation set out in the Benzene NESHAP, and the United States Court of Appeals for the District of Columbia Circuit in

NRDC

EPA,

529 F.3d 1077, concluded that EPA's interpretation of section 112(f)(2) is a reasonable one. See

NRDC

EPA,

529 F.3d at 1083 (District of Columbia Circuit, “[S]ubsection 112(f)(2)(B) expressly incorporates EPA's interpretation of the Clean Air Act from the Benzene standard, complete with a citation to the Federal Register”). (District of Columbia Circuit 2008). 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 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 38045. We discussed the maximum individual lifetime cancer risk 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 upper bound of risk based on conservative assumptions, such as continuous exposure for 24 hours per day for 70 years.”

Id.

We acknowledge that maximum individual lifetime cancer risk “does not necessarily reflect the true risk, but displays a conservative risk level which is an upper-bound that is unlikely to be exceeded.”

Id.

Understanding that there are both benefits and limitations to using maximum individual lifetime cancer risk 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 maximum individual lifetime cancer risk, 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 [maximum individual cancer risk], rather than a 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 maximum individual lifetime cancer risk 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 ample margin of safety decision process, the Agency again considers all of the health risks 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 CAA section 112(f). 54 FR 38046.

B. How did we consider the risk results in making decisions for this proposal?

As discussed in section III.A. of this preamble, we apply a two-step process for developing standards to address residual risk. In the first step, EPA determines if risks are acceptable. This determination “considers all health information, including risk estimation uncertainty, and includes a presumptive limit on maximum individual lifetime [cancer] risk (MIR)

of approximately 1-in-10 thousand [

i.e.,

100-in-1 million].” 54 FR 38045. In the second step of the process, EPA sets the standard at a level that provides an ample margin of safety “in consideration of all health information, including the number of persons at risk levels higher than approximately 1-in-1 million, as well as other relevant factors, including costs and economic impacts, technological

feasibility, and other factors relevant to each particular decision.”

Id.

Although defined as “maximum individual risk,” MIR refers only to cancer risk. MIR, one metric for assessing cancer risk, is the estimated risk were an individual exposed to the maximum level of a pollutant for a lifetime.

In past residual risk determinations, EPA presented a number of human health risk metrics associated with emissions from the category under review, including: The MIR; the numbers of persons in various risk ranges; cancer incidence; the maximum non-cancer hazard index (HI); and the maximum acute non-cancer hazard. In estimating risks, EPA considered source categories under review that are located near each other and that affect the same population. EPA provided estimates of the expected difference in actual emissions from the source category under review and emissions allowed pursuant to the source category MACT standard. EPA also discussed and considered risk estimation uncertainties. EPA is providing this same type of information in support of these actions.

However, in contrast to past determinations, this notice presents and considers additional measures of health information to support our decision-making. These are discussed in more detail in later sections of this notice, and include:

• Estimates of “total facility” cancer and non-cancer risk (risk from all HAP emissions from the facility at which the source category is located).

• Demographic analyses (analyses of the distributions of HAP-related cancer risks and non-cancer risks, across different social, demographic, and economic groups within the populations living near the facilities where these source categories are located).

• Additional estimates of the risks associated with emissions allowed by the MACT standard.

The Agency is considering all of this available health information to inform our determinations of risk acceptability and ample margin of safety under CAA section 112(f). Specifically, as explained in the Benzene NESHAP, “the first step judgment on acceptability cannot be reduced to any single factor,” and, thus, “[t]he Administrator believes that the acceptability of risk under section 112 is best judged on the basis of a broad set of health risk measures and information.” 54 FR 38044 and 38046, September 14, 1989. Similarly, with regard to making the ample margin of safety determination, the Benzene NESHAP state that “[I]n 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 cost and economic impacts of controls, technological feasibility, uncertainties, and any other relevant factors.”

Id.

The Agency acknowledges that the Benzene NESHAP provide flexibility regarding what factors the EPA might consider in making our determinations and how they might be weighed for each source category. In responding to comment on our policy under the Benzene NESHAP, EPA explained that: “The policy chosen by the Administrator permits consideration of multiple measures of health risk. Not only can the MIR figure be considered, but also incidence, the presence of non-cancer health effects, and the uncertainties of the risk estimates. In this way, the effect on the most exposed individuals can be reviewed as well as the impact on the general public. These factors can then be weighed in each individual case. This approach complies with the Vinyl Chloride mandate that the Administrator ascertain an acceptable level of risk to the public by employing [her] expertise to assess available data. It also complies with the Congressional intent behind the CAA, which did not exclude the use of any particular measure of public health risk from the EPA's consideration with respect to CAA section 112 regulations, and, thereby, implicitly permits consideration of any and all measures of health risk which the Administrator, in [her] judgment, believes are appropriate to determining what will `protect the public health.' ” 54 FR 38057.

For example, the level of the MIR is only one factor to be weighed in determining acceptability of risks. The Benzene NESHAP explain “an MIR of approximately 1-in-10 thousand should ordinarily be the upper end of the range of acceptability. As risks increase above this benchmark, they become presumptively less acceptable under CAA section 112, and would be weighed with the other health risk measures and information in making an overall judgment on acceptability. Or, the Agency may find, in a particular case, that a risk that includes MIR less than the presumptively acceptable level is unacceptable in the light of other health risk factors.”

Id.

at 38045. Similarly, with regard to the ample margin of safety analysis, the Benzene NESHAP state that: “* * * EPA believes the relative weight of the many factors that can be considered in selecting an ample margin of safety can only be determined for each specific source category. This occurs mainly because technological and economic factors (along with the health-related factors) vary from source category to source category.”

Id.

at 38061.

EPA wishes to point out that certain health information has not been considered in these decisions. In assessing risks to populations in the vicinity of the facilities in each category, we present estimates of risk associated with HAP emissions from the source category alone (source category risk estimates) and HAP emissions from the entire facilities at which the covered source categories are located (facility-wide risk estimates). We have not presented estimates of total HAP inhalation risks from all sources in the vicinity of the covered sources (

i.e.,

the sum of risks from ambient levels, emissions from the source category, facility-wide emissions, and emissions from other facilities nearby).

The Agency understands the potential importance of considering an individual's total exposure to HAP in addition to considering exposure to HAP emissions from the source category and facility. This is particularly important when assessing non-cancer risks, where pollutant-specific exposure levels (

e.g.,

Reference Concentration (RfC)) are based on the assumption that thresholds exist for adverse health effects. For example, the Agency recognizes that, although exposures attributable to emissions from a source category or facility alone may not indicate the potential for increased risk of adverse non-cancer health effects in a population, the exposures resulting from emissions from the facility in combination with emissions from all of the other sources (

e.g.,

other facilities) to which an individual is exposed may be sufficient to result in increased risk of adverse non-cancer health effects. In May 2010, the EPA Science Advisory Board (SAB) advised us “* * * that RTR assessments will be most useful to decision makers and communities if results are presented in the broader context of aggregate and cumulative risks, including background concentrations and contributions from other sources in the area.”

EPA's responses to this and all other key recommendations of the SAB's advisory on RTR risk assessment methodologies (which is available at:

http://yosemite.epa.gov/sab/sabproduct.nsf/4AB3966E263D943A8525771F00668381/$File/EPA-SAB-10-007-unsigned.pdf

) are outlined in a memo to this rulemaking docket from David Guinnup entitled,

EPA's Actions in Response to the Key Recommendations of the SAB Review of RTR Risk Assessment Methodologies.

While we are interested in placing source category and facility-wide HAP risks in the context of total HAP risks from all sources combined in the vicinity of each source, we are concerned about the uncertainties of doing so. At this point, we believe that such estimates of total HAP risks will

have significantly greater associated uncertainties than for the source category or facility-wide estimates, hence, compounding the uncertainty in any such comparison. This is because we have not conducted a detailed technical review of HAP emissions data for source categories and facilities that have not previously undergone an RTR review or are not currently undergoing such review. We are requesting comment on whether and how best to estimate and evaluate total HAP exposure in our assessments, and, in particular, on whether and how it might be appropriate to use information from EPA's National Air Toxics Assessment (NATA) to support such estimates. We are also seeking comment on how best to consider various types and scales of risk estimates when making our acceptability and ample margin of safety determinations under CAA section 112(f). Additionally, we are seeking recommendations for any other comparative measures that may be useful in the assessment of the distribution of HAP risks across potentially affected demographic groups.

C. What other actions are we addressing in this proposal?

In this proposal, we are addressing three additional types of action for some or all of these six MACT standards. For eight source categories subject to three of the MACT standards, we identified significant emission sources within the categories for which standards were not previously developed. We are proposing MACT standards for these emission sources pursuant to CAA section 112(d)(2) and (3). For four source categories subject to two of the MACT standards, we are also proposing changes to correct editorial errors, to make clarifications, and to address issues with implementation or determining compliance. We are also proposing to revise requirements in each of the six MACT standards related to emissions during periods of startup, shutdown, and malfunction (SSM).

The United States Court of Appeals for the District of Columbia Circuit vacated portions of two provisions in EPA's CAA section 112 regulations governing the emissions of HAP during periods of SSM.

Sierra Club

EPA,

551 F.3d 1019 (District of Columbia Circuit, 2008),

cert. denied, 130 S. Ct. 1735 (U.S. 2010).

Specifically, the Court vacated the SSM exemption contained in 40 CFR 63.6(f)(1) and (h)(1), that is part of a regulation, commonly referred to as the

General Provisions Rule,

that EPA promulgated under section 112 of the CAA. When incorporated into a CAA section 112(d) standard for a specific source category, these two provisions exempt sources within that source category from the requirement to comply with the otherwise applicable emission standard during periods of SSM. We are proposing to eliminate the SSM exemption in each of the six MACT standards addressed in this proposal. Consistent with

Sierra Club

EPA,

we are proposing that the established standards in these rules apply at all times. We are also proposing to revise the

General Provisions

table in each of the six MACT standards in several respects. For example, we are removing the

General Provisions'

requirement that the source develop an SSM plan. We are also removing certain recordkeeping and reporting requirements related to the SSM exemption, but we are retaining the recordkeeping and related requirements for malfunctions and request public comment on the requirements. EPA has attempted to ensure that regulatory language relating to the SSM exemption has been removed. We solicit comment on whether we have overlooked any regulatory provisions that might be inappropriate, unnecessary, or redundant based on our proposal to remove the exemption from compliance with the emission limit during periods of SSM.

Periods of startup, normal operations, and shutdown are all predictable and routine aspects of a source's operations. In contrast, malfunction is defined as a “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 * * *” (40 CFR 63.2). EPA believes that a malfunction should not be viewed as a distinct operating mode, and, therefore, any emissions that occur during malfunctions do not need to be factored into development of CAA section 112(d) standards, which, once promulgated, apply at all times. In Mossville

Environmental Action Now

EPA,

370 F.3d 1232, 1242 (District of Columbia Circuit 2004), the Court upheld as reasonable standards that had factored in variability of emissions under all operating conditions. However, nothing in CAA section 112(d) or in case law requires that EPA anticipate and account for the innumerable types of potential malfunction events in setting emission standards. See,

Weyerhaeuser

Costle,

590 F.2d 1011, 1058 (District of Columbia Circuit 1978) (“In the nature of things, no general limit, individual permit, or even any upset provision can anticipate all upset situations. After a certain point, the transgression of regulatory limits caused by ‘uncontrollable acts of third parties,’ such as strikes, sabotage, operator intoxication, or insanity, and a variety of other eventualities, must be a matter for the administrative exercise of case-by-case enforcement discretion, not for specification in advance by regulation.”) Further, it is reasonable to interpret CAA section 112(d) as not requiring EPA to account for malfunctions in setting emissions standards. For example, we note that CAA section 112 uses the concept of “best performing” sources in defining MACT, the level of stringency that major source standards must meet. Applying the concept of “best performing” to a source that is malfunctioning presents significant difficulties. The goal of best performing sources is to operate in such a way as to avoid malfunctions of their units.

Moreover, even if malfunctions were considered a distinct operating mode, we believe it would be impracticable to take malfunctions into account in setting CAA section 112(d) standards. As noted above, by definition, malfunctions are sudden and unexpected events, and it would be difficult to set a standard that takes into account the myriad different types of malfunctions that can occur across all sources in each source category. Malfunctions can also vary in frequency, degree, and duration, further complicating standard setting.

Under this proposal, in the event that a source fails to comply with the applicable CAA section 112(d) standards as a result of a malfunction event, EPA would determine an appropriate response based on, among other things, the good faith efforts of the source to minimize emissions during malfunction periods, including preventative and corrective actions, as well as root cause analyses to ascertain and rectify excess emissions. EPA would also consider whether the source's failure to comply with the CAA section 112(d) standard was, in fact, “sudden, infrequent, not reasonably preventable” and was not instead “caused in part by poor maintenance or careless operation.” 40 CRF 63.2 (definition of malfunction).

Finally, EPA recognizes that, even equipment that is properly designed and maintained can sometimes fail, and that such failure can sometimes cause or contribute to an exceedance of the relevant emission standard.

(See, e.g.,

State Implementation Plans: Policy Regarding Excessive Emissions During Malfunctions, Startup, and Shutdown

(September 20, 1999);

Policy on Excess

Emissions During Startup, Shutdown, Maintenance, and Malfunctions

(February 15, 1983)). Therefore, consistent with our recently promulgated final amendments to regulations addressing the Portland Cement category (75 FR 54970, September 9, 2010), we are proposing to add regulatory language providing an affirmative defense against civil penalties for exceedances of emission limits that are caused by malfunctions in each of the six MACT standards addressed in this proposal. We are proposing to define “affirmative defense” to mean, in the context of an enforcement proceeding, a response or defense put forward by a defendant, regarding which the defendant has the burden of proof, and the merits of which are independently and objectively evaluated in a judicial or administrative proceeding. We are also proposing regulatory provisions to specify the elements that are necessary to establish this affirmative defense.

(See

40 CFR 22.24). The proposed criteria would ensure that the affirmative defense is available only where the event that causes an exceedance of the emission limit meets the narrow definition of malfunction in 40 CFR 63.2 (sudden, infrequent, not reasonably preventable, and not caused by poor maintenance and/or careless operation). The proposed criteria also are designed to ensure that steps are taken to correct the malfunction, to minimize emissions, and to prevent future malfunctions. In any judicial or administrative proceeding, the Administrator would be able to challenge the assertion of the affirmative defense and, if the respondent has not met its burden of proving all of the requirements in the affirmative defense, appropriate penalties could be assessed in accordance with section 113 of the CAA (see also 40 CFR 22.77).

D. What specific RTR actions have previously been taken for these source categories?

For some of the 16 source categories covered by these six MACT standards, we have previously taken certain actions under the RTR program. Following is a summary of these previous actions and also a summary of additional reviews we have subsequently conducted for each source category.

1. Categories for Which RTR Decisions Have Been Finalized

There are nine source categories regulated under the Group I Polymers and Resins MACT standard. For four of these source categories (Butyl Rubber Production, Ethylene Propylene Rubber Production, Neoprene Production, and Polysulfide Rubber Production), we previously proposed and promulgated a decision not to revise the standards for purposes of the RTR provisions in CAA sections 112(d)(6) and (f)(2).

See 72 FR 70543, December 12, 2007 (proposed rule), and 73 FR 76220, December 16, 2008 (final rule). These four categories were determined to be “low-risk,” as the maximum lifetime individual cancer risks were less than 1-in-1-million, and there were no other health concerns of significance. Therefore, we determined that conducting additional risk analyses for these categories was not warranted. We are not re-opening the RTR in this notice for these four source categories, and do not seek additional comments on that prior RTR.

There are no longer any operating facilities in the United States that produce polysulfide rubber, and we do not anticipate any will begin to operate in the future.

However, for three of these four Group I Polymers and Resins source categories (Butyl Rubber Production, Ethylene Propylene Rubber Production, and Neoprene Production), we have identified significant emission sources for which MACT standards were not previously developed. In this proposal, we are proposing MACT standards for these emission sources, and we are also proposing that the residual risks after implementation of these new MACT standards will not change our previous finding that these source categories present low risks and that our obligation to review the residual risk under CAA section 112(f) has also been satisfied.

2. Categories for Which RTR Decisions Have Been Proposed, but Not Promulgated

For eight source categories covered under four of the MACT standards addressed in this proposal, we previously performed an RTR review and proposed that no revisions of the MACT standards were necessary to address residual risk and that it was not necessary to revise the existing standards under CAA section 112(d)(6). See 73 FR 60423, October 10, 2008. The MACT standards addressed in this proposal included Marine Tank Vessel Loading Operations (MTVLO), Printing and Publishing Industry, Pharmaceuticals Production, and five of the source categories covered under Group I Polymers and Resins (Epichlorohydrin Elastomers, Hypalon

Production, Nitrile Butadiene Rubber Production, Polybutadiene Rubber Production, and Styrene Butadiene Rubber and Latex Production).

Comments were received on that proposal, but no final action has been taken. This proposal presents additional analyses we have performed since the proposal, for each of these source categories with regard to the RTR. In addition, we are proposing revisions to the SSM provisions in the existing standards for these source categories, and, for several of the source categories, we are proposing MACT standards under CAA sections 112(d)(2) and (3) for emission points that were not previously regulated.

The Mineral Wool Production source category was also addressed in that same October 2008 proposal. We are not proposing any additional action for that source category in this proposal, but will do so in a separate future action. We note that there are no longer any operating facilities in the United States that produce Hypalon

, and we do not anticipate that any will begin operation in the future.

3. Categories for Which RTR Decisions Have Not Been Proposed

We have not previously proposed any RTR actions for the four source categories (Hard and Decorative Chromium Electroplating, Chromium Anodizing Tanks, and Steel Pickling—HCl Process Facilities and Hydrochloric Acid Regeneration Plants) covered by the Chromium Electroplating and Steel Pickling MACT standards. Therefore, this is our initial proposed action for these two MACT standards to address the RTR requirement. In addition, we identified significant advances in the housekeeping requirements in the chromium source categories for which we are proposing MACT standards. We are also proposing revisions to the provisions addressing SSM to ensure they are consistent with the Court decision in

Sierra Club

EPA,

551 F.3d 1019, and we are proposing changes to correct editorial errors, make clarifications, or address issues with implementation or determining compliance.

IV. Analyses Performed

As discussed above, in this notice, we are taking the following actions: (1) We are newly proposing action or supplementing our previous proposal to address the RTR requirements of CAA sections 112(d)(6) and (f)(2) for 16 source categories covered by six different MACT standards; (2) for eight of the source categories, we are proposing MACT standards for significant emission sources that are not currently subject to emission standards under the MACT standards; (3) we are proposing to revise the provisions in each of these six MACT standards to address SSM to ensure that the SSM provisions are consistent with the Court

decision in

Sierra Club

EPA,

551 F. 3d 1019; and (4) for two of the MACT standards, we are proposing amendments to correct editorial errors, to make clarifications, and to address issues with implementation or determining compliance.

A. How did we estimate risk posed by the source categories?

To support the proposed decision under the RTR for each source category, EPA conducted risk assessments that provided estimates of the MIR posed by the HAP emissions from each source in a category and by each source category, the distribution of cancer risks within the exposed populations, cancer incidence, HI for chronic exposures to HAP with non-cancer health effects, hazard quotients (HQ) for acute exposures to HAP with non-cancer health effects, and an evaluation of the potential for adverse environmental effects. The risk assessments consisted of seven primary steps, as discussed below.

The docket for this rulemaking contains the following documents which provide more information on the risk assessment inputs and models,

Draft Residual Risk Assessment for 9 Source Categories, Draft Residual Risk Assessment for Steel Pickling,

and

Draft Residual Risk Assessment for Chromium Electroplating,

as well as the memoranda for the Printing and Publishing Industry, MTVLO, Epichlorohydrin Elastomers Production, Polybutadiene Rubber Production, Styrene Butadiene Rubber Production, Nitrile Butadiene Production, and Pharmaceuticals Production source categories.

1. Establishing the Nature and Magnitude of Actual Emissions and Identifying the Emissions Release Characteristics

For the source categories included in the October 10, 2008, proposal, we compiled preliminary data sets using readily-available information, reviewed the data, and made changes where necessary, and shared these data with the public via an Advanced Notice of Proposed Rulemaking (ANPRM). 72 FR 29287, March 29, 2007. The data sets were then updated based on comments received on the ANPRM and, in some cases, with additional information gathered by EPA. For the five Group I Polymers and Resins I Production source categories included in the October 2008 proposal (Epichlorohydrin Elastomers Production, Hypalon

Production, Nitrile Butadiene Rubber Production, Polybutadiene Rubber Production, and Styrene Butadiene Rubber and Latex Production), the preliminary data sets were based on information we collected directly from industry on emissions data and emissions release characteristics. For the MTVLO, Pharmaceuticals Production, and the Printing and Publishing Industry source categories, we created the preliminary data sets using data in the 2002 National Emissions Inventory (NEI) Final Inventory, Version 1 (made publicly available on February 26, 2006), supplemented by data collected directly from industry when available. The 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. The EPA collects this information and releases an updated version of the NEI database every 3 years.

In the March 29, 2007, ANPRM, we specifically requested comment on, and updates to, these preliminary data sets. We received comments on emissions data and emissions release characteristics data for facilities in these source categories. These comments were reviewed, considered, and the emissions information was adjusted where we concluded the comments supported such adjustment. After incorporation of changes to the data sets from this public data review process, data sets were created that were used to conduct the risk assessments and other analyses that formed the basis for the proposed actions included in the October 10, 2008, proposal.

Since the proposal, we have continued to scrutinize the data sets for these source categories and to review additional data that has become available since the October 10, 2008, proposal. For the Printing and Publishing Industry source category, we became aware that some facilities had closed. We also reviewed the emissions data and had questions about the emissions of certain HAP. After contact with industry, it was determined that those emissions did not occur from those facilities. We updated the Printing and Publishing Industry data set to reflect these changes in operating facilities and emissions. For the MTVLO data set, we had concerns that several emission points in our existing data set were mislabeled, and, thus, we extracted more recent data from the NEI. For this source category, the data set is based on the 2005 NEI. For the Pharmaceuticals Production source category data set, no changes are necessary to the data set used for the proposal. For the Polymers and Resins I MACT standard source categories included in the October 10, 2008, proposal, updates have been made based on information received in response to an industry information collection survey. Documentation for industry contacts, surveys, and other information gathered to support these changes is available in the docket for this action.

For the four source categories not included in the December 10, 2008, proposal, we compiled preliminary data sets using the best available information, reviewed the data, and made changes where necessary. For the three Chromium Electroplating MACT standard source categories (Chromium Anodizing Tanks, Decorative Chromium Electroplating, and Hard Chromium Electroplating) and the Steel Pickling source category, we compiled the preliminary data sets using data in the 2005 NEI. Then, for the Steel Pickling source category, seven facilities were contacted to verify their emissions and emissions release characteristic data, and we updated the data set based on the information collected. This updated data set was used to conduct the risk assessments and other analyses that form the bases for the proposed actions.

For the Chromium Electroplating source categories, a review of the 2005 NEI data indicated that not all chromium electroplating facilities were included in the data set. To develop an emissions inventory for the entire industry that could be used for modeling, an additional data set was developed based on facilities with known addresses—a total of 1,629 facilities compared to 122 facilities in the NEI. Emissions for each type of plant were estimated based on the model plants developed for the original Chromium Electroplating MACT standard,

with hard chromium model plants having the highest emissions, followed by decorative chromium electroplating, and then chromium anodizing. If the type of electroplating performed at a specific plant was unknown, we assumed these facilities were hard chrome electroplating when we estimated emissions and risks for those facilities. Although we knew that, by doing so, we would be overestimating emissions of chromium, and, therefore, also of risk, we made this conservative assumption because we did not have complete information, and we chose to overestimate to preserve an

ample margin of safety in the risk assessment upon which our risk modeling would be based. This analysis and a supplemental assessment are fully described in section V.A.

See

EPA-HQ-OAR-2010-0600,

Model Plant Data Used to Estimate Risk from Chromium Electroplating Sources.

2. Establishing the Relationship Between Actual Emissions and MACT-Allowable Emissions Levels

The available emissions data in the NEI and from other sources typically represent the mass of emissions actually emitted during the specified annual time period. These “actual” emission levels are often lower than the level of emissions that a facility might be allowed to emit and still comply with the MACT standard. The emissions level allowed to be emitted by the MACT standard is referred to as the “MACT-allowable” emissions level. This represents the highest emission level that could be emitted by the facility without violating the MACT standard.

We discussed the use of both MACT-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 76609, December 21, 2006, respectively). In those previous actions, we noted that assessing the risks at the MACT-allowable level is inherently reasonable since these risks 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. (54 FR 38044, September 14, 1989.) It is reasonable to consider actual emissions because sources typically seek to perform better than required by emission standards to provide an operational cushion to accommodate the variability in manufacturing processes and control device performance.

As described above, the actual emissions data were compiled based on the NEI, information gathered from facilities and States, and information received in response to the ANPRM for several of the source categories. To estimate emissions at the MACT-allowable level, we developed a ratio of MACT-allowable to actual emissions for each emissions source type in each source category, based on the level of control required by the MACT standard compared to the level of reported actual emissions and available information on the level of control achieved by the emissions controls in use. For example, if there was information to suggest several facilities in a source category were controlling storage tank emissions by 98 percent while the MACT standards required only 92-percent control, we would estimate that MACT-allowable emissions from these emission points could be as much as four times higher (8-percent allowable emissions compared with 2-percent actually emitted), and the ratio of MACT-allowable to actual would be 4:1 for this emission point type at the facilities in this source category. After developing these ratios for each emission point type in each source category, we next applied these ratios on a facility-by-facility basis to the maximum chronic risk values from the inhalation risk assessment to obtain facility-specific maximum risk values based on MACT-allowable emissions.

3. Conducting Dispersion Modeling, Determining Inhalation Exposures, and Estimating Individual and Population Inhalation Risks

Both long-term and short-term inhalation exposure concentrations and health risks from each of the source categories addressed in this proposal were estimated using the Human Exposure Model (Community and Sector HEM-3 version 1.1.0). The HEM-3 performs three of the primary risk assessment activities listed above: (1) Conducting dispersion modeling to estimate the concentrations of HAP in ambient air, (2) estimating long-term and short-term inhalation exposures to individuals residing within 50 km of the modeled sources, and (3) estimating individual and population-level inhalation risks using the exposure estimates and quantitative dose-response information.

The dispersion model used by HEM-3 is AERMOD, which is one of EPA's preferred models for assessing pollutant concentrations from industrial facilities.

To perform the dispersion modeling and to develop the preliminary risk estimates, HEM-3 draws on three data libraries. The first is a library of meteorological data, which is used for dispersion calculations. This library includes 1 year of hourly surface and upper air observations for 130 meteorological stations, selected to provide coverage of the United States and Puerto Rico. A second library of United States 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. These values are available at

http://www.epa.gov/ttn/atw/toxsource/summary.html

and are discussed in more detail later in this section.

U.S. EPA. Revision to the

Guideline on Air Quality Models: Adoption of a Preferred General Purpose (Flat and Complex Terrain) Dispersion Model and Other Revisions

(70 FR 68218, November 9, 2005).

A census block is generally the smallest geographic area for which census statistics are tabulated.

In developing the risk assessment for chronic exposures, we used the estimated annual average ambient air concentration of each of the HAP emitted by each source for which we have emissions data in the source category. The air concentrations at each nearby census block centroid were used as a surrogate for the chronic inhalation exposure concentration for all the people who reside in that census block. We calculated the MIR for each facility as the cancer risk associated with a lifetime (70-year period) of 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 of the HAP multiplied by its Unit Risk Estimate (URE), which is an upper bound estimate of an individual's probability of contracting cancer over a lifetime of exposure to a concentration of 1 microgram of the pollutant per cubic meter of air. For residual risk assessments, we generally use URE values from EPA's Integrated Risk Information System (IRIS).

For carcinogenic pollutants without EPA IRIS values, we look to other reputable sources of cancer dose-response values, often using California Environmental Protection Agency (CalEPA) URE values, where available. In cases where new, scientifically credible dose response values have been developed in a manner consistent with EPA guidelines and have undergone a peer review process similar to that used by EPA, we may use such dose-response values in place of, or in addition to, other values.

The IRIS information is available at

http://www.epa.gov/IRIS.

We note here that several carcinogens have a mutagenic mode of action.

For these compounds, the age-dependent adjustment factors described in EPA's

Supplemental Guidance for Assessing Susceptibility from Early-Life Exposure to Carcinogens

were applied. This adjustment has the effect of increasing the estimated lifetime risks for these pollutants by a factor of 1.6.

In addition, although only a small fraction of the total polycyclic organic matter (POM) emissions were reported as individual compounds, EPA expresses carcinogenic potency for compounds in this group in terms of benzo[a]pyrene equivalence, based on evidence that carcinogenic POM have the same mutagenic mechanism of action as does benzo[a]pyrene. For this reason, EPA's Science Policy Council

recommends applying the

Supplemental Guidance

to all carcinogenic polycyclic aromatic hydrocarbons for which risk estimates are based on relative potency. Accordingly, we have applied the

Supplemental Guidance

to all unspeciated POM mixtures.

U.S. EPA, 2006. Performing risk assessments that include carcinogens described in the

Supplemental Guidance

as having a mutagenic mode of action.

Science Policy Council Cancer Guidelines Implementation Workgroup Communication II:

Memo from W.H. Farland dated June 14, 2006.

http://epa.gov/osa/spc/pdfs/CGIWGCommunication_II.pdf.

U.S. EPA, 2005.

Supplemental Guidance for Assessing Early-Life Exposure to Carcinogens.

EPA/630/R-03/003F.

http://www.epa.gov/ttn/atw/childrens_supplement_final.pdf.

Only one of these mutagenic compounds, benzo[a]pyrene, is emitted by any of the sources covered by this proposal.

U.S. EPA, 2005.

Science Policy Council Cancer Guidelines Implementation Workgroup Communication I:

Memo from W.H. Farland dated October 4, 2005, to Science Policy Council.

http://www.epa.gov/osa/spc/pdfs/canguid1.pdf.

Incremental individual lifetime cancer risks associated with emissions from the source category were estimated as the sum of the risks for each of the carcinogenic HAP (including those classified as carcinogenic to humans, likely to be carcinogenic to humans, and suggestive evidence of carcinogenic potential

) emitted by the modeled source. Cancer incidence and the distribution of individual cancer risks for the population within 50 km of any source were also estimated for the source category as part of these assessments by summing individual risks. A distance of 50 km is consistent with both the analysis supporting the 1989 Benzene NESHAP (54 FR 38044) and the limitations of Gaussian dispersion modeling.

These classifications also coincide with the terms “known carcinogen, probable carcinogen, and possible carcinogen,” respectively, which are the terms advocated in the EPA's previous

Guidelines for Carcinogen Risk Assessment,

published in 1986 (51 FR 33992, September 24, 1986). Summing the risks of these individual compounds to obtain the cumulative cancer risks is an approach that was recommended by the EPA's SAB in their 2002 peer review of EPA's NATA entitled,

NATA—Evaluating the National-scale Air Toxics Assessment 1996 Data—an SAB Advisory,

available at:

http://yosemite.epa.gov/sab/sabproduct.nsf/214C6E915BB04E14852570CA007A682C/$File/ecadv02001.pdf.

To assess risk of non-cancer health effects from chronic exposures, we summed the HQ for each of the HAP that affects a common target organ system to obtain the HI for that target organ system (or target organ-specific HI, TOSHI). The HQ is the estimated exposure divided by the chronic reference level, which is either the U.S. EPA RfC, defined as “an estimate (with uncertainty spanning perhaps an order of magnitude) of a continuous inhalation exposure to the human population (including sensitive subgroups) that is likely to be without an appreciable risk of deleterious effects during a lifetime,” or, in cases where an RfC is not available, the CalEPA Chronic Reference Exposure Level (REL), defined as “the concentration level at or below which no adverse health effects are anticipated for a specified exposure duration.” As noted above, in cases where new, scientifically credible dose-response values have been developed in a manner consistent with EPA guidelines and have undergone a peer review process similar to that used by EPA, we may use those dose-response values in place of, or in addition to, other values.

Screening estimates of acute exposures and risks were also evaluated for each of the HAP at the point of highest off-site exposure for each facility (

i.e.,

not just the census block centroids) assuming that a person is located at this spot at a time when both the peak (hourly) emission rate and hourly dispersion conditions (1991 calendar year data) occur. In each case, acute HQ values were calculated using best available, short-term health threshold values. These acute threshold values include REL, Acute Exposure Guideline Levels (AEGL), and Emergency Response Planning Guidelines (ERPG) for 1-hour exposure durations. As discussed below, we used conservative assumptions for emission rates, meteorology, and exposure location for our acute analysis.

As described in the CalEPA's

Air Toxics Hot Spots Program Risk Assessment Guidelines, Part I, The Determination of Acute Reference Exposure Levels for Airborne Toxicants,

an acute REL value (

http://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 is termed the REL. REL values are based on the most sensitive, relevant, adverse health effect reported in the medical and toxicological literature. REL values 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 value does not automatically indicate an adverse health impact.”

AEGL values were derived in response to recommendations from the National Research Council (NRC). As described in “Standing Operating Procedures (SOP) of the National Advisory Committee on Acute Exposure Guideline Levels for Hazardous Substances” (

http://www.epa.gov/opptintr/aegl/pubs/sop.pdf

“the NRC's previous name for acute exposure levels—community emergency exposure levels (CEEL)— was replaced by the term AEGL to reflect the broad application of these values to planning, response, and prevention in the community, the workplace, transportation, the military, and the remediation of Superfund sites.” This document also states that AEGL values “represent threshold exposure limits for the general public and are applicable to emergency exposures ranging from 10 minutes to 8 hours.” The document lays out the purpose and objectives of AEGL by stating (page 21) that “the 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.” In detailing the intended application of AEGL values, the document states (page 31) that ”[i]t is anticipated that the AEGL values will be used for regulatory and nonregulatory purposes by United States Federal and State agencies, and possibly the international community in conjunction with chemical emergency response, planning, and prevention programs. More specifically, the AEGL values will be used for conducting various risk assessments to aid in the development of emergency preparedness and prevention plans, as well as real-time emergency response actions, for accidental chemical releases at fixed facilities and from transport carriers.”

NAS, 2001.

Standing Operating Procedures for Developing Acute Exposure Levels for Hazardous Chemicals,

page 2.

The AEGL-1 value is then specifically defined as “the airborne concentration of a substance above which it is predicted that the general population, including susceptible individuals, could experience notable discomfort, irritation, or certain asymptomatic nonsensory effects. However, the effects are not disabling and are transient and reversible upon cessation of exposure.” The document also notes (page 3) that, “Airborne concentrations below AEGL-1 represent exposure levels that can produce mild and progressively increasing but transient and nondisabling odor, taste, and sensory irritation or certain asymptomatic, nonsensory effects.” Similarly, the document defines AEGL-2 values as “the airborne concentration (expressed as ppm or mg/m

) 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.”

ERPG values are derived for use in emergency response, as described in the American Industrial Hygiene Association's document entitled,

Emergency Response Planning Guidelines (ERPG) Procedures and Responsibilities

(

http://www.aiha.org/1documents/committees/ERPSOPs2006.pdf

), which states that, “Emergency Response Planning Guidelines were developed for emergency planning and are intended as health-based guideline concentrations for single exposures to chemicals.”

The ERPG-1 value is defined as “the maximum airborne concentration below which it is believed that nearly all individuals could be exposed for up to 1 hour without experiencing other than mild transient adverse health effects or without perceiving a clearly defined, objectionable odor.” Similarly, the ERPG-2 value is defined as “the maximum airborne concentration below which it is believed that nearly all individuals could be exposed for up to 1 hour without experiencing or developing irreversible or other serious health effects or symptoms which could impair an individual's ability to take protective action.”

ERP Committee Procedures and Responsibilities.

1 November 2006. American Industrial Hygiene Association.

As can be seen from the definitions above, the AEGL and ERPG values include the similarly-defined severity levels 1 and 2. For many chemicals, a severity level 1 value AEGL or ERPG has not been developed; in these instances, higher severity level AEGL-2 or ERPG-2 values are compared to our modeled exposure levels to screen for potential acute concerns.

Acute REL values for 1-hour exposure durations are typically lower than their corresponding AEGL-1 and ERPG-1 values. Even though their definitions are slightly different, AEGL-1 values are often the same as the corresponding ERPG-1 values, and AEGL-2 values are often equal to ERPG-2 values. Maximum HQ values from our acute screening risk assessments typically result when basing them on the acute REL value for a particular pollutant. In cases where our maximum acute HQ value exceeds 1, we also report the HQ value based on the next highest acute threshold (usually the AEGL-1 and/or the ERPG-1 value).

To develop screening estimates of acute exposures, we developed estimates of maximum hourly emission rates by multiplying the average actual annual hourly emission rates by a factor to cover routinely variable emissions. We chose the factor to use based on process knowledge and engineering judgment and with awareness of a Texas study of short-term emissions variability, which showed that most peak emission events, in a heavily-industrialized 4-county area (Harris, Galveston, Chambers, and Brazoria Counties, Texas), 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.

This analysis is provided in Appendix 4 of the

Draft Residual Risk Assessment for Source Categories Report

and is available in the docket for this action. Considering this analysis, unless specific process knowledge provided an alternate value, a conservative screening multiplication factor of 10 was applied to the average annual hourly emission rate in these acute exposure screening assessments.

See http://www.tceq.state.tx.us/compliance/field_ops/eer/index.html

or docket to access the source of these data.

In cases where all acute HQ values from the screening step were less than or equal to 1, 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 1, additional site-specific data were considered to develop a more refined estimate of the potential for acute impacts of concern. The data refinements considered included using a peak-to-mean hourly emissions ratio based on source category-specific knowledge or data (rather than 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. Ideally, we would prefer to have continuous measurements over time to see how the emissions vary by each hour over an entire year. Having a frequency distribution of hourly emission rates over a year would allow us to perform a probabilistic analysis to estimate potential threshold exceedances and their frequency of occurrence. Such an evaluation could include a more complete statistical treatment of the key parameters and elements adopted in this screening analysis. However, we recognize that having this level of data is rare, hence our use of the multiplier approach.

4. Conducting Multipathway Exposure and Risk Modeling

The potential for significant human health risks due to exposures via routes other than inhalation (

i.e.,

multipathway exposures) and the potential for adverse environmental impacts were evaluated in a three-step process. In the first step, we determined whether any facilities emitted any HAP known to be persistent and bio-accumulative in the environment (PB-HAP). There are 14 PB-HAP compounds or compound classes identified for this screening in EPA's Air Toxics Risk Assessment Library (available at

http://www.epa.gov/ttn/fera/risk_atra_vol1.html

). They are cadmium compounds, chlordane, chlorinated dibenzodioxins and furans, dichlorodiphenyldichloroethylene, heptachlor, hexachlorobenzene, hexachlorocyclohexane, lead compounds, mercury compounds, methoxychlor, polychlorinated biphenyls, POM, toxaphene, and trifluralin.

In the second step of the screening process, we determined whether the facility-specific emission rates of each of the emitted PB-HAP were large enough to create the potential for significant non-inhalation risks. To facilitate this step, we have developed emission rate thresholds for each PB-HAP using a hypothetical screening exposure scenario developed for use in conjunction with the TRIM.FaTE model. The hypothetical screening scenario was subjected to a sensitivity analysis to ensure that its key design parameters were established such that environmental media concentrations were not underestimated (

i.e.,

to minimize the occurrence of false negatives, or results that suggest that risks might be acceptable when, in fact, actual risks are high), and to also minimize the occurrence of false positives for human health endpoints.

We call this application of the TRIM.FaTE model TRIM-Screen. The facility-specific emission rates of each of the PB-HAP in each source category were compared to the emission threshold values for each of the PB-HAP identified in the source category data sets.

For all of the facilities in the source categories addressed in this proposal, all of the PB-HAP emission rates were less than the emission threshold values. As a result of this, multi-pathway exposures and environmental risks were deemed negligible and no further analysis was performed. If the emission rates of the PB-HAP had been above the emission threshold values, the source categories would have been further evaluated for potential non-inhalation risks and adverse environmental effects in a third step through site-specific refined assessments using EPA's TRIM.FaTE model.

For further information on the multi-pathway analysis approach, see the residual risk documentation as referenced in section IV.A of this preamble.

5. Assessing Risks Considering Emissions Control Options

In addition to assessing baseline inhalation risks and screening for potential multi-pathway risks, for some source categories, where appropriate, we also estimated risks considering the potential emission reductions that would be achieved by the particular control options under consideration. The inhalation and multi-pathway risks estimated, as described above, at the actual and MACT-allowable levels represent the actual and maximum allowable operating conditions of the facilities in the source categories analyzed. For source categories where emission reduction options were available, we estimated risk based on the expected emissions reductions that would be realized with those additional emissions controls. In these cases, the expected emissions reductions were applied to the specific HAP and emissions sources in the source category data set. The results of the risk analyses considering the application of emissions controls are included in the residual risk documentation as referenced in section IV.A of this preamble, which is available in the docket for this action.

6. Conducting Other Risk-Related Analyses, Including Facility-Wide Assessments and Demographic Analyses

a. Facility-Wide Risk

To put the source category risks in context, we also examined the risks from the entire “facility,” where the facility includes all HAP-emitting operations within a contiguous area and under common control. In other words, for each facility that includes one or more sources from one of the source categories under review, we examined the HAP emissions not only from the source category of interest, but also emissions of HAP from all other emission sources at the facility. The emissions data for generating these “facility-wide” risks were obtained from the 2005 NEI (available at

http://www.epa.gov/chief/net/2005inventory.html

). We analyzed risks due to the inhalation of HAP that are emitted “facility-wide” for the populations residing within 50 km of each facility, consistent with the methods used for the source category analysis described above. For these facility-wide risk analyses, the modeled source category risks were compared to the facility-wide risks to determine the portion of facility-wide risks that could be attributed to each of the six source categories being addressed in this proposal, we specifically examined the facility that was associated with the highest estimate of risk and determined the percentage of that risk attributable to the source category of interest. The risk documentation available through the docket for this action provides all the facility-wide risks and the percentage of source category contribution for all source categories assessed.

The methodology and the results of the facility-wide analyses for each source category are included in the residual risk documentation as referenced in section IV.A of this preamble, which is available in the docket for this action.

b. Demographic Analysis

To examine the potential for any environmental justice issues that might be associated with each source category, we evaluated the distributions of HAP-related cancer and non-cancer risks across different social, demographic, and economic groups within the populations living near the facilities where these source categories are located. The development of demographic analyses to inform the consideration of environmental justice issues in EPA rulemakings is an evolving science. The EPA offers the demographic analyses in this rulemaking as examples of how such analyses might be developed to inform such consideration, and invites public comment on the approaches used and the interpretations made from the results, with the hope that this will support the refinement and improve utility of such analyses for future rulemakings.

For this analysis, we analyzed risks due to the inhalation of HAP in two separate ways. In the first approach, we focus the analysis on the total populations residing within 5 km of each facility (source category and facility-wide), regardless of their estimated risks, and examine the distributions of estimated risk across the various demographic groups within those 5 km circles. The distance of 5 km was chosen for the first approach to be consistent with previous demographic analyses performed at EPA, such as the one which was performed in support of the recent proposal for the Boilers NESHAP. In the second approach, we focus the analysis only on the populations within 5 km

of any facility estimated to have exposures to HAP which result in cancer risks of 1-in-1 million or greater or non-cancer hazard indices of 1 or greater (based on the emissions of the source category or the facility, respectively). Once again, we examine the distributions of those risks across various demographic groups. In each approach, we compare the percentages of particular demographic groups to the total number of people in those demographic groups nationwide. In this preamble, we only present the results of the second approach since it focuses on the significant risks from either the source category or the facility-wide emissions. The results of both approaches including other risk metrics such as average risks for the exposed populations are documented in source category-specific technical reports in the docket for each of the source categories covered in this proposal.

Generally, we have found that using a 5 km radius in the analysis will capture more than 90 percent of all the individuals with cancer risks above 1-in-1 million. In the future, we plan to extend these analyses to cover the entire modeled domain for a facility (50 km radius) to capture all individuals with risks above 1-in-1 million from the affected facilities.

For example, the report pertaining to the Hard Chromium Electroplating source category is entitled

Risk and Technology Review—Analysis of Socio-Economic Factors for Populations Living Near Hard Chromium Electroplating Facilities.

The basis for the risk values used in these analyses were the modeling results obtained from the HEM-3 model described above. The risk values for each census block were linked to a database of information from the 2000 Decennial census that includes data on race and ethnicity, age distributions, poverty status, household incomes, and education level. The Census Department Landview ® database was the source of the data on race and ethnicity, and the

data on age distributions, poverty status, household incomes, and education level was obtained from the 2000 Census of Population and Housing Summary File 3 (SF3) Long Form. While race and ethnicity census data are available at the block group level, the age and income census data are only available at the census block level (which includes an average of 26 blocks or an average of 1,350 people). Where census data are available at the block group level but not the block level, we assumed that all blocks within the block group have the same distribution of ages and incomes as the block group.

For each source category, the analysis results include the distribution of estimated lifetime inhalation cancer and chronic non-cancer risks for different racial and ethnic groups, different age groups, adults with and without a high school diploma, people living in households below the national median income, and for people living below the poverty line among the population living near these facilities. The specific census population categories studied include:

• Total population.

• White.

• African American (or Black).

• Native Americans.

• Other races and multiracial.

• Hispanic or Latino.

• Children 18 years of age and under.

• Adults 19 to 64 years of age.

• Adults 65 years of age and over.

• Adults without a high school diploma.

• Households earning under the national median income.

• People living below the poverty line.

It should be noted that these categories overlap in some instances, resulting in some populations being counted in more than one category (

e.g.,

other races and multiracial and Hispanic). In addition, while not a specific census population category, we also examined risks to the category “Minorities,” which is defined as all race population categories except white. Since these demographic analysis methods are still evolving, EPA specifically solicits comment on the inclusion of other demographic categories (

e.g.,

“Hispanic and Non-white”) in our future analyses.

For further information about risks to the populations local to the facilities in these source categories, we also evaluated the estimated distribution of inhalation cancer and chronic non-cancer risks associated with the HAP emissions from all the emissions sources at the facility (

i.e.,

facility-wide). This analysis used the facility-wide RTR modeling results and the census data described above.

The methodology and the results of the demographic analyses for each source category are included in the residual risk documentation as referenced in section IV.A of this preamble, which is available in the docket for this action.

7. Considering Uncertainties in Risk Assessment

Uncertainty and the potential for bias are inherent in all risk assessments, including those performed for the source categories addressed in this proposal. Although uncertainty exists, we believe the approach that we took, which used conservative tools and assumptions, ensures that our decisions are health-protective. A brief discussion of the uncertainties in the emissions data sets, dispersion modeling, inhalation exposure estimates, and dose-response relationships follows below. A more thorough discussion of these uncertainties is included in the

Draft Residual Risk Assessment for the Steel Pickling Source Category

(July 2010),

Draft Residual Risk Assessment for the Chromium Electroplating Source Category

(July 2010),

Draft Residual Risk Assessment for 9 Source Categories

(August 2008), and the

Risk and Technology Review (RTR) Assessment Plan

(November 2006), each of which are available in the docket for this action.

a. Uncertainties in the Emissions Data Sets

Although the development of the RTR data sets involved quality assurance/quality control processes, the accuracy of emissions values will vary depending on the source of the data, the degree to which data is incomplete or missing, the degree to which assumptions made to complete the data sets are inaccurate, errors in estimating emissions values, and other factors. The emission values considered in this analysis generally are annual totals that do not reflect short-term fluctuations during the course of a year or variations from year to year. In contrast, the estimates of peak hourly emission rates for the acute effects screening assessment were based on multiplication factors applied to the average annual hourly emission rates (the default factor is 10), which are intended to account for emission fluctuations due to normal facility operations. In some cases, more refined estimates were used for source categories where the screening estimates did not “screen out” all sources and more specific information was available. Additionally, for some source categories our estimate of the number of facilities may not represent the number of facilities that we have in our notice of proposed rulemaking data set. There is also significant uncertainty for some source categories in the identification of sources as major or area in the NEI.

b. Uncertainties in Dispersion Modeling

While the analysis employed EPA's recommended regulatory dispersion model, AERMOD, we recognize that there is uncertainty in ambient concentration estimates associated with any model, including AERMOD. Where possible, model options (

e.g.,

rural/urban, plume depletion, chemistry) were selected to provide an overestimate of ambient air concentrations of the HAP. 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 HAP 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 between census blocks in the modeling domain were 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. Using the census block centroid to predict chronic exposures tends to over-predict exposures for people in the census block who live further from the facility and under-predict exposures for people in the census block who live closer to the facility. Thus, using the census block centroid to predict chronic exposures may lead to a potential understatement or overstatement of the true maximum

impact, but is an unbiased estimate of average risk and incidence.

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.

The assessments evaluate the cancer inhalation risks associated with pollutant exposures over a 70-year period, which is the assumed lifetime of an individual. 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 United States facilities), will influence the risks posed by a given source category. Depending on the characteristics of the industry, these factors will likely 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 as high, depending on the 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.

U.S. EPA.

National-Scale Air Toxics Assessment for 1996.

(EPA 453/R-01-003; January 2001; page 85.)

In addition to the uncertainties highlighted above, there are several factors specific to the acute exposure assessment that should be highlighted. The accuracy of an acute inhalation exposure assessment depends on the simultaneous occurrence of independent factors that may vary greatly, such as hourly emissions rates, meteorology, and human activity patterns. In this assessment, we assume that individuals remain for 1 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

There are uncertainties inherent in the development of the reference values used in our risk assessments for cancer effects from chronic exposures and non-cancer effects from both chronic and acute exposures. Some uncertainties may be considered quantitatively, and others generally are expressed in qualitative terms. We note as a preface to this discussion a point on dose-response uncertainty that is brought out in EPA's

2005 Cancer Guidelines;

namely, that “the primary goal of EPA actions is protection of human health; accordingly, as an Agency policy, risk assessment procedures, including default options that are used in the absence of scientific data to the contrary, should be health protective.” (

EPA 2005 Cancer Guidelines,

pages 1-7.) This is the approach followed here as summarized in the next several paragraphs. A complete detailed discussion of uncertainties and variabilities in dose-response relationships is given in the residual risk documentation as referenced in section IV.A of this preamble, which is available in the docket for this action.

Cancer URE values used in our risk assessments are those that have been developed to generally provide an upper bound estimate of risk. That is, they represent a “plausible upper limit to the true value of a quantity” (although this is usually not a true statistical confidence limit).

In some circumstances, the true risk could be as low as zero; however, in other circumstances the risk could also be greater.

When developing an upper bound estimate of risk and to provide risk values that do not underestimate risk, health-protective default approaches are generally used. To err on the side of ensuring adequate health-protection, EPA typically uses the upper bound estimates rather than lower bound or central tendency estimates in our risk assessments, an approach that may have limitations for other uses (

e.g.,

priority-setting or expected benefits analysis).

IRIS glossary (

http://www.epa.gov/NCEA/iris/help_gloss.htm

An exception to this is the URE for benzene, which is considered to cover a range of values, each end of which is considered to be equally plausible, and which is based on maximum likelihood estimates.

Chronic non-cancer reference (RfC and RfD) values represent chronic exposure levels that are intended to be health-protective levels. Specifically, these values provide an estimate (with uncertainty spanning perhaps an order of magnitude) of daily oral exposure (RfD) or of a continuous inhalation exposure (RfC) to the human population (including sensitive subgroups) that is likely to be without an appreciable risk of deleterious effects during a lifetime. To derive values that are intended to be “without appreciable risk,” the methodology relies upon an uncertainty factor (UF) approach (U.S. EPA, 1993, 1994) which includes consideration of both uncertainty and variability. When there are gaps in the available information, UF are applied to derive reference values that are intended to protect against appreciable risk of deleterious effects. UF are commonly default values,

e.g.,

factors of 10 or 3, used in the absence of compound-specific data; where data are available, UF may also be developed using compound-specific information. When data are limited, more assumptions are needed and more UF are used. Thus, there may be a greater tendency to overestimate risk in the sense that further study might support development of reference values that are higher (

i.e.,

less potent) because fewer default assumptions are needed. However, for some pollutants it is possible that risks may be underestimated.

According to the NRC report,

Science and Judgment in Risk Assessment

(NRC, 1994) “[Default] options are generic approaches, based on general scientific knowledge and policy judgment, that are applied to various elements of the risk assessment process when the correct scientific model is unknown or uncertain.” The 1983 NRC report,

Risk Assessment in the Federal Government: Managing the Process,

defined default option as “the option chosen on the basis of risk assessment policy that appears to be the best choice in the absence of data to the contrary” (NRC, 1983a, p. 63). Therefore, default options are not rules that bind the Agency; rather, the Agency may depart from them in evaluating the risks posed by a specific substance when it believes this to be appropriate. In keeping with EPA's goal of protecting public health and the environment, default assumptions are used to ensure that risk to chemicals is not underestimated (although defaults are not intended to overtly overestimate risk). See EPA 2004,

An examination of EPA Risk Assessment Principles and Practices,

EPA/100/B-04/001 available at:

http://www.epa.gov/osa/pdfs/ratf-final.pdf.

While collectively termed “UF,” these factors account for a number of different quantitative considerations when using observed animal (usually rodent) or human toxicity data in the development of the RfC. The UF are intended to account for: (1) Variation in susceptibility among the members of the human population (

i.e.,

inter-individual variability); (2) uncertainty in extrapolating from experimental animal data to humans (

i.e.,

interspecies differences); (3) uncertainty in extrapolating from data obtained in a study with less-than-lifetime exposure

(

i.e.,

extrapolating from sub-chronic to chronic exposure); (4) uncertainty in extrapolating the observed data to obtain an estimate of the exposure associated with no adverse effects; and (5) uncertainty when the database is incomplete or there are problems with the applicability of available studies. Many of the UF used to account for variability and uncertainty in the development of acute reference values are quite similar to those developed for chronic durations, but they more often use individual UF values that may be less than 10. UF are applied based on chemical-specific or health effect-specific information (

e.g.,

simple irritation effects do not vary appreciably between human individuals, hence a value of 3 is typically used), or based on the purpose for the reference value (see the following paragraph). The UF applied in acute reference value derivation include: (1) Heterogeneity among humans; (2) uncertainty in extrapolating from animals to humans; (3) uncertainty in lowest observable adverse effect (exposure) level to no observable effect (exposure) level adjustments; and (4) uncertainty in accounting for an incomplete database on toxic effects of potential concern. Additional adjustments are often applied to account for uncertainty in extrapolation from observations at one exposure duration (

e.g.,

4 hours) to derive an acute reference value at another exposure duration (

e.g.,

1 hour).

Not all acute reference values are developed for the same purpose and care must be taken when interpreting the results of an acute assessment of human health effects relative to the reference value or values being exceeded. Where relevant to the estimated exposures, the lack of threshold values at different levels of severity should be factored into the risk characterization as potential uncertainties.

Although every effort is made to identify peer-reviewed reference values for cancer and non-cancer effects for all pollutants emitted by the sources included in this assessment, some pollutants have no peer-reviewed reference values for cancer or chronic non-cancer or acute effects. Since exposures to these pollutants cannot be included in a quantitative risk estimate, an understatement of risk for these pollutants at environmental exposure levels is possible.

Additionally, chronic reference values for several of the compounds included in this assessment are currently under EPA IRIS review and revised assessments may determine that these pollutants are more or less potent than the current value. We may re-evaluate residual risks for the final rulemaking if, as a result of these reviews, a dose-response metric changes enough to indicate that the risk assessment supporting this notice may significantly understate human health risk.

e. Uncertainties in the Multipathway and Environmental Effects Assessment

We generally assume that when exposure levels are not anticipated to adversely affect human health, they also are not anticipated to adversely affect the environment. We generally rely on the facility-specific levels of PB-HAP emissions to determine whether a full assessment of the multi-pathway and environmental effects is necessary. Because facility-specific PB-HAP emission levels were so far below levels which would trigger a refined assessment of multi-pathway impacts, we are confident that these types of impacts are insignificant for these source categories.

f. Uncertainties in the Facility-Wide Risk Assessment

The same uncertainties discussed above exist with regard to the facility-wide risk assessments. Additionally, the degree of uncertainty associated with facility-wide emissions and risks is generally greater because we have not completed our review of emissions data for source categories not currently undergoing an RTR review.

g. Uncertainties in the Demographic Analysis

Our analysis of the distribution of risks across various demographic groups is subject to the typical uncertainties associated with census data (

e.g.,

errors in filling out and transcribing census forms), as well as the additional uncertainties associated with the extrapolation of census-block group data (

e.g.,

income level and education level) down to the census block level.

B. How did we perform the technology review?

Our technology review is focused on the identification and evaluation of “developments in practices, processes, and control technologies.” If a review of available information identifies such developments, then we conduct an analysis of the technical feasibility of requiring the implementation of these developments, along with the impacts (costs, emission reductions, risk reductions,

etc.

). We then make a decision on whether it is necessary to amend the regulation to require these developments.

Based on specific knowledge of each source category, we began by identifying known developments in practices, processes, and control technologies. For the purpose of this exercise, we considered any of the following to be a “development”:

• Any add-on control technology or other equipment that was not identified and considered during MACT development;

• Any improvements in add-on control technology or other equipment (that was identified and considered during MACT development) that could result in significant additional emission reduction;

• Any work practice or operational procedure that was not identified and considered during MACT development; and

• Any process change or pollution prevention alternative that could be broadly applied that was not identified and considered during MACT development.

In addition to looking back at practices, processes, or control technologies reviewed at the time we developed the MACT standard, we reviewed a variety of sources of data to aid in our evaluation of whether there were additional practices, processes, or controls to consider. One of these sources of data was subsequent air toxics rules. Since the promulgation of the MACT standards for the source categories addressed in this proposal, EPA has developed air toxics regulations for a number of additional source categories. In these subsequent air toxic regulatory actions, we consistently evaluated any new practices, processes, and control technologies. We reviewed the regulatory requirements and/or technical analyses associated with these subsequent regulatory actions to identify any practices, processes, and control technologies considered in these efforts that could possibly be applied to emission sources in the source categories under this current RTR review.

We also consulted EPA's RACT/BACT/LAER Clearinghouse (RBLC). The terms “RACT,” “BACT,” and “LAER” are acronyms for different program requirements under the CAA provisions addressing the national ambient air quality standards. Control technologies, classified as RACT (Reasonably Available Control Technology), BACT (Best Available Control Technology), or LAER (Lowest Achievable Emission Rate) apply to stationary sources depending on whether the sources are existing or new, and on the size, age, and location of the facility. BACT and

LAER (and sometimes RACT) are determined on a case-by-case basis, usually by State or local permitting agencies. EPA established the RBLC to provide a central data base of air pollution technology information (including technologies required in source-specific permits) to promote the sharing of information among permitting agencies and to aid in identifying future possible control technology options that might apply broadly to numerous sources within a category or apply only on a source-by-source basis. The RBLC contains over 5,000 air pollution control permit determinations that can help identify appropriate technologies to mitigate many air pollutant emission streams. We searched this database to determine whether any practices, processes, or control technologies are included for the types of processes used for emission sources (

e.g.,

tanks or vents) in the source categories under consideration in this proposal.

We also requested information from industry regarding developments in practices, processes, or control technology. Finally, we reviewed other information sources, such as State or local permitting agency databases and industry-supported databases.

C. How did we perform the analyses for the other actions being proposed?

For several of the source categories considered in this proposal, we identified significant emission points that were not previously regulated under MACT. For these emission points, consistent with the requirements of CAA sections 112(d)(2) and (3), we identified the MACT floor for existing and new sources and considered beyond-the-floor options.

We also reviewed the SSM provisions of each of the six MACT standards in light of

Sierra Club

EPA,

551 F.3d 1019. As part of this review, we evaluated available information and engaged industry concerning the type of activities and emissions that occur during periods of startup or shutdown.

Finally, we identified potential revisions to these MACT standards to correct or clarify regulatory requirements. In the years since promulgation and compliance with the MACT standards, EPA has received comments and suggestions for improving the clarity of the MACT standards in general, as well as rule-specific comments for some individual MACT standards. These comments include such things as identification of editorial errors in the rule, clarification of existing rule text, regulatory obstacles to effective implementation of or compliance with the rule provisions. EPA has also independently identified these types of issues. We are proposing rule changes where appropriate.

V. Analyses Results and Proposed Decisions

This section of the preamble provides background information on the MACT standards and source categories, the results of our RTR for each source category, our proposed actions to address significant unregulated emission points for a number of source categories, our proposed decisions concerning the SSM provisions in each of the six MACT standards, and the specific clarifications we are proposing for selected MACT standards.

A. What are the results and proposed decisions for the Chromium Electroplating source categories?

1. Overview of the Source Categories and MACT Standard

National Emission Standards for Chromium Emissions from Hard and Decorative Chromium Electroplating and Chromium Anodizing Tanks (Chromium Electroplating MACT standards) were promulgated on January 25, 1995 (60 FR 4963), and codified at 40 CFR part 63, subpart N. The Chromium Electroplating MACT standards regulate emissions of chromium compounds from three related source categories: Hard Chromium Electroplating, Decorative Chromium Electroplating, and Chromium Anodizing. Within these source categories, the MACT standards apply to all plants, both major and area sources, regardless of size.

The Hard Chromium Electroplating source category consists of facilities that plate base metals with a relatively thick layer of chromium using an electrolytic process. Hard chromium electroplating provides a finish that is resistant to wear, abrasion, heat, and corrosion. These facilities plate large cylinders and industrial rolls used in construction equipment and printing presses, hydraulic cylinders and rods, zinc die castings, plastic molds, engine components, and marine hardware.

The Decorative Chromium Electroplating source category consists of facilities that plate base materials such as brass, steel, aluminum, or plastic with layers of copper and nickel, followed by a relatively thin layer of chromium to provide a bright, tarnish- and wear-resistant surface. Decorative chromium electroplating is used for items such as automotive trim, metal furniture, bicycles, hand tools, and plumbing fixtures.

The Chromium Anodizing source category consists of facilities that use chromic acid to form an oxide layer on aluminum to provide resistance to corrosion. The chromium anodizing process is used to coat aircraft parts (such as wings and landing gears), as well as architectural structures that are subject to high stress and corrosive conditions.

The HAP emission sources subject to the Chromium Electroplating NESHAP are the tanks in which the chromium deposition takes place. For hard chromium and decorative chromium electroplating facilities, the emission sources are electroplating tanks. For the Chromium Anodizing source category, the emission sources are anodizing tanks.

The primary emission controls used by the facilities in these source categories include packed bed scrubbers, mesh pad mist eliminators, composite mesh pad (CMP) systems, high efficiency particulate air (HEPA) filters, and wetting agent/fume suppressants (WAFS). Most decorative chromium electroplating plants comply with the MACT standards by using WAFS in the tank bath to control surface tension, which in turn reduces emissions. Some plants use a combination of WAFS and add-on control to meet the MACT emission limits. If a facility controls emissions using an add-on control device, the tank is generally equipped with a hood and duct work to exhaust emissions through the control device and out the stack. However, when WAFS are used as the only means of emission control, the tanks often are not equipped with exhaust hoods. In such cases, emissions from the tank are fugitive and are exhausted to the outside using wall-mounted exhaust fans.

We estimate that there are approximately 1,770 plants that are currently subject to the Chromium Electroplating MACT standards. Of these, we estimate that there are 790 hard chromium electroplating plants, 740 decorative chromium electroplating plants, and 240 chromium anodizing plants. A detailed description of how the number of each type of plant was estimated can be found in the

Estimated Number of Chromium Electroplating Plants

document available in the docket for this action. Some facilities perform more than one type of chromium electroplating or anodizing. For purposes of our estimates, we classified facilities as hard chromium, decorative chromium, or chromium anodizing based on the primary type of electroplating operation performed at the facility. Some chromium

electroplating facilities electroplate items that are used internally in the manufacturing process at the same facility or within the same company. For example, some large printing facilities electroplate their printing rollers in house, and the chromium electroplating processes are located at the same site as the printing and publishing processes.

2. What data were used in our risk analyses?

For the Chromium Electroplating source categories, we compiled a preliminary data set using data in the 2005 NEI. A review of the NEI resulted in the identification of data for 122 chromium electroplating facilities. These data were reviewed and the data for eight hard chromium and six decorative chromium electroplating plants were revised based on information in the facilities' permits or permit applications. Additional data were available for 44 facilities through responses to a CAA section 114 information request that was sent to facilities for the Plating and Polishing Area Source rule. The data for these facilities were added to the NEI data set, and, as with the original data, represent actual emission levels for these electroplating and anodizing facilities. Most of these facilities have low emissions, which are generally less than 2 pounds per year (lbs/yr). These 166 facilities now included in the 2005 NEI comprise approximately 9 percent of the estimated 1,770 facilities covered by the MACT standards, and include 63 hard chromium electroplating, 96 decorative chromium electroplating, and 7 chromium anodizing facilities.

This data set of 166 facilities was modeled to determine the maximum individual cancer risk, the population cancer risk, the cancer incidence, and the maximum chronic non-cancer risk for the three source categories based on actual emissions. The maximum individual cancer risk and the maximum chronic non-cancer risk estimated from this data set were also compared to the maximum individual cancer risk and the maximum chronic non-cancer risk estimated from MACT-allowable emissions for the three source categories.

The National Association of Surface Finishers provided OMB with data for 15 plants. We have placed this information in the docket for this rulemaking.

The Occupational Safety and Health Administration adopted a lower permissible exposure limit for hexavalent chromium in 2006.

To address the possibility that the small number of facilities included in the 166-facility data set might not be fully representative of the source categories and their risks, we developed an additional data set. In the development of this data set, we used “model plants” developed for the original MACT standard to represent the individual facilities. For hard and decorative chromium electroplating, we used three model plants (large, medium, and small) that represent average characteristics for each of these groups. For each of these plant sizes, there is an annual emissions rate (lbs/yr) that is derived from the design and operating parameters, and is specific to the size and type of model plant. For chromium anodizing, we have two model plants (large and small). The model plants were based on data collected during development of the original MACT standards from 1988 to 1993 from more than 100 facilities that responded to an Information Collection Request (ICR) for the chromium electroplating and anodizing industry. Data from site visits and other information also were used in developing the model plants. A complete description of the model plants developed for the MACT standard is provided in the Background Information Document (BID) for the original MACT standard (Chromium Electroplating BID).

The basis for this additional data set is 1,629 chromium electroplating facilities with known addresses.

For about half of these facilities, the type of electroplating performed is known, but the size of the facility is not known. For the remaining facilities, neither the type of chromium electroplating process or processes, nor the facility size is known.

There is some overlap between the 1,629 facilities with known addresses and the 166 facilities for which we have emissions data based on the NEI and the data collection request.

For use in the risk analysis, the limited available data were used to divide these facilities into six groups. Facilities in three of the six groups were assigned to be hard chromium electroplating facilities. Those groups include: hard chromium facilities; facilities with combined hard chromium operations and other electroplating or anodizing; and facilities with unknown processes. Together, these three groups yielded a total of 1,219 plants, all of which we modeled as hard chromium electroplating facilities. This total, in addition to the 63 hard chromium electroplating facilities in the 2005 NEI data set, yields a total of 1,282 facilities, which is substantially higher than the 790 hard chromium facilities that we estimate exist in the United States. However, because hard chromium facilities have the highest emissions among the three source categories, we made these selections as a conservative or health-protective assumption.

To represent the decorative chromium electroplating facilities, we combined two of the six groups of facilities; decorative chromium facilities and facilities that perform both decorative chromium and chromium anodizing. This results in 319 decorative chromium facilities in this data set, which, even when combined with the 96 decorative chromium electroplating facilities in the 2005 NEI data set, is less than the 740 facilities that we believe exist in the industry. Because we modeled all of the unknown electroplating type facilities as the highest-emitting hard chromium electroplating facilities, we consider this assessment to be conservative, even though it appears to under-represent decorative chromium facilities.

Similarly, the last of the six groups are all known chromium anodizing facilities. This group includes 73 facilities, and, when combined with the 7 chromium anodizing facilities in the 2005 NEI data set, still represents only about a third of the 240 facilities chromium anodizing facilities. Again, we believe this is conservative because those facilities not modeled as chromium anodizing plants were modeled as the higher emitting hard chromium facilities in the analysis.

To estimate the risks for this assessment, we needed to establish estimated emissions for each of the electroplating and anodizing types. To ensure that we did not underestimate cancer risk to the most exposed individual, we originally planned to use the large plant emission factors that we had developed for the original MACT standard to represent all model plants for each type of chromium electroplating processing. In reviewing available emissions data, we found that, while the large plant emission factors adequately represent the average chromium emissions from known large decorative chromium electroplating and large chromium anodizing facilities, they are not representative of the average chromium emissions from large hard chromium electroplating facilities.

The emission factor for large hard chromium electroplating developed for the original MACT standard was 35.3 lbs/yr. However, in comparing this emission factor to available emissions data for individual facilities, we find that this emissions factor is unrealistically high and does not represent the average level of emissions for large facilities as we would expect to see under the current MACT standard. As explained more fully in the

Model Plant Data Used to Estimate Risk from

Chromium Electroplating Sources

document available in the docket for this action, based on the large model plant design flow rate and operating hours, a large hard chromium model plant operating at the MACT emission limit of 0.015 milligrams per dry standard cubic meter (mg/dscm) would emit a maximum of only 23.6 lbs/yr of chromium compounds. Moreover, the available data on actual emissions for hard chromium electroplating plants indicate there are only 4 plants with annual emissions greater than 10 lbs/yr. As a result, we determined that the large size model plant emissions factor, as defined for the original MACT standard, is not representative of existing large hard chromium electroplating facilities on a nationwide basis. On the other hand, the emission factor associated with a medium size hard chromium electroplating model plant (9.26 lbs/yr) falls between the 90th percentile (8.04 lbs/yr) and the 95th percentile (11.6 lbs/yr) of the available emissions data for hard chromium electroplating facilities. Because this emission factor, which was originally developed for medium sized facilities at the time the MACT standard was developed, is representative of the emissions from large facilities, the emissions factor of 9.26 lbs/yr was used to represent current large hard chromium electroplating facilities. Thus, for purposes of this residual risk review, we refer to 9.26 lbs/yr as the emissions factor for a “large” hard chromium electroplating facility.

We believe the approach of using the “large” facility emissions factor to represent all facility sizes is reasonable to ensure that we did not underestimate maximum individual cancer risk. Although we believe that only a small percentage of the facilities are large, we recognize that we do not have emissions data for approximately 90 percent of the sources. Thus, by assuming all sources are large, we have ensured that we will not underestimate the maximum individual risk.

For hard chromium electroplating, the model plant emission factors for small, medium, and large facilities range from 0.55 to 9.26 lbs/yr. While we expect only 10 percent of the facilities to be large, based on the distribution of model plant sizes developed for the MACT standard, we used the emissions factor for a large facility (9.26 lbs/yr) for all of the 1,219 facilities that we considered as hard chromium electroplating facilities. Similarly, for decorative chromium electroplating, the emission factors for small, medium, and large facilities are 0.065, 0.27, and 2.65 lbs/yr, respectively, and the large facility emissions factor was used in the risk assessment for decorative chromium. For the Decorative Chromium category, we estimate that only 5 percent of the facilities are large, based upon the distribution of decorative chromium plants nationwide when the original NESHAP were developed. Finally, for chromium anodizing, the emission factor for small facilities is 0.036 lb/yr, and for large facilities, is 0.44 lb/yr. The large facility emissions factor (0.44 lb/yr) was used in the conservative analysis for all of the anodizing facilities even though we estimate that only 25 percent are large.

Population risk indicators can be greatly overstated when highly conservative emission estimates are applied to every facility in the source category. Recognizing this fact, we performed a supplemental analysis to better address nationwide average emission levels and assess the sensitivity of our population risk estimates. Thus, as described further below, the supplemental analysis was performed to understand the degree to which the risk might be overstated, and, thus, how much weight to attach to the conservative analysis. The conservatism of this risk assessment is one factor that we consider in determining whether the risk is acceptable within the meaning of the Benzene NESHAP.

For the supplemental analysis, we assigned unique emission factors to each of the 6 groups of facilities in our 1,629 facility data set. These emission factors were developed to better estimate the average emissions for all of the sources within each group. The new emission factors are:

• 2.24 lbs/yr for known hard chromium electroplating facilities,

• 0.225 lb/yr for known decorative chromium electroplating facilities,

• 0.137 lb/yr for known chromium anodizing facilities,

• 1.23 lbs/yr for facilities with combinations of hard chromium electroplating and either decorative electroplating or anodizing,

• 0.181 lb/yr for facilities with combinations of decorative electroplating and anodizing, and

• 1.11 lbs/yr for facilities where the type of process (electroplating or anodizing) is unknown.

A detailed explanation for how these emission factors were derived can be found in the

Model Plant Data Used to Estimate Risk from Chromium Electroplating Sources

available in the docket for this action. These weighted average emission factors account for the plant type (hard chromium electroplating, decorative chromium electroplating, or chromium anodizing) and the distribution of plant sizes (large, medium, or small). For example, the average emissions factor for hard chromium electroplating (2.24 lbs/yr) is the weighted average of the model plant emission factors for large plants (10 percent of plants at 9.26 lbs/yr per plant), medium plants (20 percent of plants at 4.63 lbs/yr per plant, and small plants (70 percent of plants at 0.55 lb/yr per plant). This distribution of plant sizes is based on actual data collected during development of the original MACT rule. We have no reason to believe the distribution of facility sizes has changed significantly since then.

The uncertainties associated with both the conservative analysis and the supplemental analysis include the estimated distribution of plant types and sizes as well as the facility emissions factors. Although the type of plants used in the NEI analysis is based on a variety of reliable sources, including ICR responses for the Plating and Polishing NESHAP, trade association data, data from State agencies, and information from Web sites, we were unable to identify the plant type for nearly half of the data set. For those plants of unknown type, we used the highest emissions factor, which corresponds to a large hard chromium plant, in the conservative analysis. For the supplemental analysis, we developed an emissions factor using a weighted average across all plant types and sizes. For all plants that were modeled, we are soliciting additional information on actual and MACT-allowable emissions, plant type, and plant size. More information about the development of the model plants can be found in the

Model Plant Data Used to Estimate Risk from Chromium Electroplating Sources

document available in the docket for this action.

In all the data sets, chromium compounds account for all the HAP emissions from the Chromium Electroplating and Chromium Anodizing source categories. For the Hard Chromium Electroplating source category, in the NEI-based data set, chromium VI compounds account for 98 percent of the emissions, with chromium III and chromium trioxide compounds comprising the remaining HAP. In both the NEI and model plant emission estimates, we made the conservative assumption that 100 percent of the emissions are chromium VI compounds. For the Decorative Chromium Electroplating source category, in the NEI-based data set, chromium VI compounds account for 94 percent of the emissions, with chromium III and chromium trioxide compounds comprising the remaining HAP. In both emission estimates, we

made the conservative assumption that 100 percent of the emissions are chromium VI compounds. For the Chromium Anodizing source category, in the NEI-based data set, chromium VI compounds account for 99 percent of the emissions with chromium III compounds comprising the remaining HAP. In both emission estimates, we made the conservative assumption that 100 percent of the emissions are chromium VI compounds.

3. What are the results of the risk assessments and analyses?

We conducted an inhalation risk assessment for each of the three source categories: Hard Chromium Electroplating, Decorative Chromium Electroplating, and Chromium Anodizing. Also, for each source category, we conducted an assessment of facility-wide risk, and performed a demographic analysis of population risks. As noted above, we developed two data sets for these source categories, one based primarily on NEI data for 166 sources, and one based on model plant data for 1,629 sources.

The following tables present the combined results from the data sets. Table A.1 provides an overall summary of the maximum individual inhalation risk assessment results, and Table A.2 provides population risk assessment results for the Hard Chromium Electroplating, Decorative Chromium Electroplating, and Chromium Anodizing source categories.

Table A.1—Chromium Electroplating and Anodizing Maximum Individual Inhalation Risk Assessment Results*

Source category

Number of facilities

(NEI/model plant)

Maximum individual

cancer risk

(in 1 million)

Actual

emissions

level

Allowable emissions level

Maximum

chronic non-cancer

TOSHI

Actual

emissions

level

Allowable emissions level

Maximum off-site acute non-cancer HQ

Hard Chromium Electroplating

63/1,219

0.06

0.09

Not applicable

Decorative Chromium Electroplating

96/337

0.06

Not applicable

Chromium Anodizing

7/73

0.004

Not applicable

* All results are for impacts out to 50 km from each source in the categories.

Number of facilities evaluated in the risk analysis: the first number refers to the NEI data set, and the second number applies to the conservative emission estimate.

Maximum individual excess lifetime cancer risk.

Maximum TOSHI. The target organ with the highest TOSHI for the Hard Chromium Electroplating, Decorative Chromium Electroplating, and Chromium Anodizing source categories is the respiratory system.

The maximum estimated acute exposure concentration was divided by available short-term threshold values to develop an array of HQ values. HQ values shown use the lowest available acute threshold value, which, in most cases, is the REL. When HQ values exceed 1, we also show HQ values using the next lowest available acute threshold. See section IV.A. of this preamble for explanation of acute threshold values.

NA = not applicable. There are no HAP with acute dose-response benchmark values, so no acute HQ were calculated for these source categories. See section IV.A of this preamble for an explanation of acute threshold values.

Table A.2—Chromium Electroplating and Anodizing Population Risk Inhalation Risk Assessment Results

Source category

Number of

facilities

(NEI/model plant)

Conservative assessment

population at risk

≥ 1-in-1 million

≥ 10-in-1

million

Conservative annual

cancer

incidence

(cases per year)

Supplemental assessment

population at risk

≥ 1-in-1 million

≥ 10-in-1

million

Supplemental annual

cancer

incidence

(case per year)

Hard Chromium Electroplating

63/1,219

14,200,000

71,000

0.8

360,000

5,100

0.1

Decorative Chromium Electroplating

96/337

390,000

4,000

0.08

30,000

1,300

0.01

Chromium Anodizing

7/73

2,700

0.003

540

0.001

As shown in Table A.1, the results of the inhalation risk assessment for the Hard Chromium Electroplating source category indicate the maximum lifetime individual cancer risk could be as high as 70-in-1 million, based on actual emissions, and as high as 90-in-1 million based on allowable emissions. This maximum individual cancer risk is based on the highest risk facility out of the 63 actual facilities and the 1,219 model plants. The highest risk facility is one for which we have design and operating data, and we believe it is also both the largest and highest emitting hard chromium electroplating facility in the United States. Thus, we believe this level accurately reflects the maximum individual exposure. The maximum chronic non-cancer TOSHI value could be 0.06, based on the actual emissions level, and up to 0.09 based on allowables. This value is also based on known emission levels from the largest facility in the nation. A non-cancer TOSHI of one or less is not of human health concern.

The total estimated national cancer incidence from hard chromium electroplating facilities based on actual emission levels is 0.8 excess cancer cases per year, or one case in every 1.25 years for the conservative assessment. Our risk assessment shows 14.2 million people exposed to a cancer risk greater than 1-in-1 million and 71,000 people exposed to a cancer risk of at least 10-in-1 million.

As noted above, we conducted a supplemental analysis to determine the weight to give to the conservative risk analysis. That supplemental analysis estimates 0.1 excess cancer cases per year, or one case in every 10 years. Additionally, it estimates a population exposure of 360,000 people at 1-in-1 million cancer risk. For a cancer risk of at least 10-in-1 million, the population exposed decreases to 5,100.

Based on the 2005 NEI data set for the Decorative Chromium Electroplating

source category, the maximum lifetime individual cancer risk could be as high as 70-in-1 million, and the maximum chronic non-cancer TOSHI value could be up to 0.06, based on the actual emissions level.

We do not believe the maximum lifetime individual cancer risk and the maximum chronic non-cancer TOSHI value would be any higher than this based on allowable emissions. The total estimated population risks from the conservative risk assessment of the decorative chromium electroplating facilities based on actual emission levels is 390,000 people exposed to a cancer risk greater than 1-in-1 million and 0.08 excess cancer cases per year, or one case in every 12 years.

There is uncertainty regarding the operating status of the facility (reported to be closed) associated with the maximum lifetime individual cancer risk. Prior to any final rulemaking action, we will investigate this situation and revise the risk analysis and results accordingly.

Based on our conservative risk assessment, we believe the risks are low, and, as explained further below, are proposing that the risks are acceptable for the Decorative Chromium source category. Although we did not need to consider the supplemental analysis that we conducted for Decorative Chromium to help guide our conclusion about the uncertainty of the risk assessment results, we note that the supplemental assessment shows 30,000 people exposed to a cancer risk greater than 1-in-1 million and 0.01 excess cancer case per year, or one case in every 100 years.

Based on the 2005 NEI data set for the Chromium Anodizing source category, the maximum lifetime individual cancer risk could be as high as 5-in-1 million and the maximum chronic non-cancer TOSHI value could be up to 0.004, based on the actual emissions level. The total estimated population risks from the conservative assessment of the chromium anodizing facilities based on actual emission levels is 2,700 people exposed to a cancer risk greater than 1-in-1 million and 0.003 excess cancer cases per year, or one case in every 333 years.

Based on our conservative risk assessment, we believe the risks are low, and, as explained further below, are proposing that the risks are acceptable for the Chromium Anodizing source category. Although we did not need to consider the supplemental analysis that we conducted for Chromium Anodizing to help guide our conclusion about the uncertainty of the risk assessment results, we note that the supplemental assessment shows 540 people exposed to a cancer risk greater than 1-in-1 million and 0.001 excess cancer case per year, or one case in every 1,000 years.

Also, as there were no reported emissions of PB-HAP for these three source categories, we do not expect the potential for human health multipathway risks or adverse environmental impacts.

Our analyses of potential differences between actual emission levels and emissions allowable under the MACT standards are based on emissions test data from specific facilities. A comparison of these test results to allowable emissions at these facilities indicates that the ratio of MACT-allowable to actual emissions varies considerably from facility to facility. As a result, a uniform factor was not available to apply to all facilities. However, for the Hard Chromium Electroplating source category, we did evaluate the facility that was modeled as having the highest maximum individual lifetime cancer risk (70-in-1 million) based on actual emissions. Our analysis indicates that this facility, if operated at the allowable emissions limit, could have a maximum individual lifetime cancer risk as high as 90-in-1 million. Furthermore, the available data indicate that no other hard chromium electroplating facility would have a cancer risk that high if operated at the allowable emissions limit.

For the Decorative Chromium Electroplating source category, we performed a similar analysis of the available data and concluded that the maximum individual lifetime cancer risk would not exceed 70-in-1 million for any facility that operated at the allowable emissions limit. As stated earlier, because most chromium anodizing facilities use WAFS, we believe actual emissions are essentially the same as allowable emissions. Thus, we believe that the MIR based on allowable emissions would be the same as that based on actual emissions,

i.e.,

5-in-1 million.

Table A.3 displays the results of the facility-wide risk assessment for actual emissions of all sources at the facility as reported in the NEI. We did not perform a facility-wide risk assessment based on allowable emissions, as explained in the documentation referenced in section IV.A of this preamble, which is available in the docket for this action.

Table A.3—Chromium Electroplating and Anodizing Facility-Wide Risk Assessment Results

Source category

Maximum

facility-wide

individual

cancer risk

(in 1 million)

Source