National Emissions Standards for Hazardous Air Pollutants: Secondary Lead Smelting

Federal RegisterMay 19, 2011

Ask Donna

What actually matters in this document.

Text

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[EPA-HQ-OAR-2011-0344; FRL-9303-4]

RIN 2060-AQ68

National Emissions Standards for Hazardous Air Pollutants: Secondary Lead Smelting

AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Proposed rule.

SUMMARY:

EPA is proposing amendments to the national emissions standards for hazardous air pollutants for Secondary Lead Smelting to address the results of the residual risk and technology review that EPA is required to conduct by the Clean Air Act. These proposed amendments include revisions to the stack emissions limits for lead; revisions to the fugitive dust emissions control requirements; the addition of total hydrocarbons emissions limits for reverberatory, electric, and rotary furnaces; the addition of emissions limits and work practice requirements for dioxins and furans; and the modification and addition of testing and monitoring and related notification, recordkeeping, and reporting requirements. We are also proposing to revise provisions addressing periods of startup, shutdown, and malfunction to ensure that the rules are consistent with a recent court decision.

DATES:

Comments must be received on or before July 5, 2011. 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 June 20, 2011.

Public Hearing.

If anyone contacts EPA requesting to speak at a public hearing by May 31, 2011, a public hearing will be held on June 3, 2011.

ADDRESSES:

Submit your comments, identified by Docket ID Number EPA-HQ-OAR-2011-0344, 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 Number EPA-HQ-OAR-2011-0344.

•

Fax:

(202) 566-9744, Attention Docket ID Number EPA-HQ-OAR-2011-0344.

•

Mail:

U.S. Postal Service, send comments to: EPA Docket Center, EPA West (Air Docket), Attention Docket ID Number EPA-HQ-OAR-2011-0344, 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 Number EPA-HQ-OAR-2011-0344. 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 Number EPA-HQ-OAR-2011-0344. EPA's policy is that all comments received will be included in the public docket without change and may be made available on-line 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.

EPA has established a docket for this rulemaking under Docket ID Number EPA-HQ-OAR-2011-0344. 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.

If a public hearing is held, it will begin at 10 a.m. on June 3, 2011 and will be held at EPA's campus in Research Triangle Park, North Carolina, or at an alternate facility nearby. Persons interested in presenting oral testimony or inquiring as to whether a public hearing is to be held should contact Ms. Virginia Hunt, Office of Air Quality Planning and Standards, Sector Policies and Programs Division, (D243-02), U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711;

telephone number:

(919) 541-0832.

FOR FURTHER INFORMATION CONTACT:

For questions about this proposed action, contact Mr. Chuck French, Sector Policies and Programs Division (D243-02), Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, telephone (919) 541-7912;

fax number:

(919) 541-5450; and

e-mail address:

french.chuck@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, North Carolina 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 the NESHAP to a particular entity, contact the appropriate person listed in Table 1 of this preamble.

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

NESHAP for:

OECA Contact

OAQPS Contact

Secondary Lead Smelting

Maria Malave, (202) 564-7027

malave.maria@epa.gov

Chuck French, (919) 541-7912,

french.chuck@epa.gov

EPA Office of Enforcement and Compliance Assurance.

EPA Office of Air Quality Planning and Standards.

SUPPLEMENTARY INFORMATION:

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:

ADAF age-dependent adjustment factors

AEGL acute exposure guideline levels

AERMOD air dispersion model used by the HEM-3 model

ANPRM advance notice of proposed rulemaking

ATSDR Agency for Toxic Substances and Disease Registry

BACT best available control technology

BLDS bag leak detection system

CAA Clean Air Act

CBI Confidential Business Information

CEMS continuous emissions monitoring system

CFR Code of Federal Regulations

CTE central tendency exposure

D/F dioxins and furans

EJ environmental justice

EPA Environmental Protection Agency

ERPG Emergency Response Planning Guidelines

ERT Electronic Reporting Tool

HAP hazardous air pollutants

HEM-3 Human Exposure Model, Version 3

HEPA high efficiency particulate air

HHRAP Human Health Risk Assessment Protocols

HI Hazard Index

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 emissions rate

lb/yr pounds per year

MACT maximum achievable control technology

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

MDL method detection level

mg/acm milligrams per actual cubic meter

mg/dscm milligrams per dry standard cubic meter

mg/m

milligrams per cubic meter

MIR maximum individual risk

MRL minimum risk level

NAAQS National Ambient Air Quality Standard

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

NEI National Emissions Inventory

NESHAP National Emissions Standards for Hazardous Air Pollutants

NOAEL no observed adverse effects level

NRC National Research Council

NTTAA National Technology Transfer and Advancement Act

O&M operation and maintenance

OAQPS Office of Air Quality Planning and Standards

ODW Office of Drinking Water

OECA Office of Enforcement and Compliance Assurance

OHEA Office of Health and Environmental Assessment

OMB Office of Management and Budget

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

PM particulate matter

POM polycyclic organic matter

ppmv parts per million volume

RACT reasonably available control technology

RBLC RACT/BACT/LAERClearinghouse

REL reference exposure level

RFA Regulatory Flexibility Act

RfC reference concentration

RfD reference dose

RIA Regulatory Impact Analysis

RME reasonable maximum exposure

RTR residual risk and technology review

SAB Science Advisory Board

SBA Small Business Administration

SCC Source Classification Codes

SF3 2000 Census of Population and Housing Summary

SIP State Implementation Plan

SOP standard operating procedures

SSM startup, shutdown, and malfunction

TEF toxic equivalency factors

TEQ toxic equivalency quotient

THC total hydrocarbons

TOSHI target organ-specific hazard index

TPY tons per year

TRIM Total Risk Integrated Modeling System

TTN Technology Transfer Network

UF uncertainty factor

μ/m

microgram per cubic meter

UL upper limit

UMRA Unfunded Mandates Reform Act

UPL upper predictive limit

URE unit risk estimate

VOC volatile organic compounds

VOHAP volatile organic hazardous air pollutants

WESP wet electrostatic precipitator

WHO World Health Organization

WWW worldwide Web

Organization of this Document. The information in this preamble is organized as follows:

I. General Information

A. What is the statutory authority for this action?

B. Does this action apply to me?

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

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

II. Background

A. Overview of the Source Category and MACT Standards

B. What data collection activities were conducted to support this action?

III. Analyses Performed

A. Addressing Unregulated Emissions Sources

B. How did we estimate risks posed by the source category?

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

D. How did we perform the technology review?

E. What other issues are we addressing in this proposal?

IV. Analyses Results and Proposed Decisions

A. What are the results of our analyses and proposed decisions regarding unregulated emissions sources?

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

C. What are our proposed decisions based on risk acceptability and ample margin of safety?

D. What are the results and proposed decisions based on our technology review?

E. What other actions are we proposing?

F. What is the relationship of the Secondary Lead Smelting standards proposed in today's action and implementation of the lead NAAQS?

G. Compliance Dates

V. Summary of Cost, Environmental, and Economic Impacts

A. What are the affected sources?

B. What are the air quality impacts?

C. What are the cost impacts?

D. What are the economic impacts?

E. What are the benefits?

VI. Request for Comments

VII. Submitting Data Corrections

VIII. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review and Executive Order 13563: Improving Regulation and Regulatory Review

B. Paperwork Reduction Act

C. Regulatory Flexibility Act

D. Unfunded Mandates Reform Act

E. Executive Order 13132: Federalism

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

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

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

I. National Technology Transfer and Advancement Act

J. Executive Order 12898: Federal Actions To Address Environmental Justice in Minority Populations and Low-Income Populations

I. General Information

A. What is the statutory authority for this action?

Section 112 of the CAA establishes a two-stage regulatory process to address emissions of hazardous air pollutants (HAP) from stationary sources. In the first stage, after EPA has identified categories of sources emitting one or more of the HAP listed in CAA section 112(b), CAA section 112(d) calls for us to promulgate NESHAP for those sources. “Major sources” are those that emit or have the potential to emit 10 tons per year (tpy) or more of a single HAP or 25 tpy or more of any combination of HAP. For major sources, these technology-based standards must reflect the maximum degree of emissions 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 must require the maximum degree of emissions reduction through the application of measures, processes, methods, systems, or techniques, including, but not limited to, measures that (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 standards may take the form of design, equipment, work practice, or operational standards where EPA first determines either that, (A) a pollutant cannot be emitted through a conveyance designed and constructed to emit or capture the pollutants, 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 emissions 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 emissions 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 considerations of the cost of achieving the emissions reductions, any non-air quality health and environmental impacts, and energy requirements.

EPA is then required to review these technology-based standards and 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, and, in particular, is not obligated to recalculate the MACT floors.

NRDC

EPA

, 529 F.3d 1077, 1084 (DC Cir., 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 the risks posed (or potentially posed) by sources after implementation of the MACT standards, the public health significance of those risks, and EPA's recommendations as to legislation regarding such remaining risk. EPA prepared and submitted this report (

Residual Risk Report to Congress

, EPA-453/R-99-001) in March 1999. Congress did not act in response to the report, thereby triggering EPA's obligation under CAA section 112(f)(2) to analyze and address residual risk.

Section 112(f)(2) of the CAA requires us to determine, for source categories subject to certain MACT standards, whether those emissions standards provide an ample margin of safety to protect public health. If the MACT standards that apply to a source category emitting a HAP that is “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 one-in-one 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 (CAA section 112(f)(2)(A)). This requirement is procedural. It mandates that EPA establish CAA section 112(f) residual risk standards if certain risk thresholds are not satisfied, but does not determine the level of those standards.

NRDC

EPA

, 529 F. 3d at 1083. The second sentence of CAA section 112(f)(2) sets out the substantive requirements for residual risk standards: protection of public health with an ample margin of safety based on EPA's interpretation of this standard in effect at the time of the Clean Air Act amendments.

Id.

This refers to the Benzene NESHAP, described in the next paragraph. EPA may adopt residual risk standards equal to existing MACT standards if EPA determines that the existing standards are sufficiently protective, even if (for example) excess cancer risks to a most exposed individual are not reduced to less than one-in-one million.

Id.

at 1083, (“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”). Section 112(f)(2) of the CAA further authorizes EPA to adopt more stringent standards, if necessary “to prevent, taking into consideration costs, energy, safety, and other relevant factors, an adverse environmental effect.”

“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.

As just noted, CAA section 112(f)(2) expressly preserves our use of the two-step process for developing standards to address any residual risk and our interpretation of “ample margin of safety” developed in the

National Emissions Standards for Hazardous Air Pollutants: Benzene Emissions From Maleic Anhydride Plants, Ethylbenzene/Styrene Plants, Benzene Storage Vessels,

Benzene Equipment Leaks, and Coke By-Product Recovery Plants

(Benzene NESHAP) (54 FR 38044, September 14, 1989). The 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 necessary 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 EPA's interpretation set out in the Benzene NESHAP, and the court in

NRDC

EPA

concluded that EPA's interpretation of CAA section 112(f)(2) is a reasonable one. See

NRDC

EPA

, 529 F.3d at 1083 (DC Cir. 2008), which says “[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

.” See also,

A Legislative History of the Clean Air Act Amendments of 1990

, volume 1, p. 877 (Senate debate on Conference Report). We also 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 risks 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 rather considers 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 DC Circuit's en banc

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-emissions 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. Does this action apply to me?

The regulated industrial source category that is the subject of this proposal is listed in Table 2 of this preamble. Table 2 of this preamble is not intended to be exhaustive, but rather provides a guide for readers regarding the entities likely to be affected by this proposed action. These standards, once finalized, will be directly applicable to affected sources. Federal, State, local, and Tribal government entities are not affected by this proposed action. As defined in the source category listing report published by EPA in 1992, the Secondary Lead Smelting source category is defined as any facility at which lead-bearing scrap materials (including, but not limited to lead acid batteries) are recycled by smelting into elemental lead or lead alloys.

For clarification purposes, all references to lead emissions in this preamble mean “lead compounds” (which is a listed HAP) and all references to lead

production mean elemental lead (which is not a listed HAP as provided under CAA section 112(b)(7)).

USEPA. Documentation for Developing the Initial Source Category List—Final Report, USEPA/OAQPS, EPA-450/3-91-030, July, 1992.

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

Source category

NESHAP

NAICS code

MACT code

Secondary Lead Smelting

331492

0205

North American Industry Classification System.

Maximum Achievable Control Technology.

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

In addition to being available in the docket, an electronic copy of this proposal will also be available on the World Wide Web (WWW) through the EPA's 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 estimates and other data that were used as inputs to the risk assessments.

D. 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-ROMas CBI and then identify electronically within the disk or CD-ROMthe 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-ROMor disk that does not contain CBI, mark the outside of the disk or CD-ROMclearly 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, North Carolina 27711, Attention Docket ID Number EPA-HQ-OAR-2011-0344.

II. Background

A. Overview of the Source Category and MACT Standards

The NESHAP (or MACT rule) for the Secondary Lead Smelting source category was promulgated on June 13, 1997 (62 FR 32216) and codified at 40 CFR part 63, subpart X. As promulgated in 1997, the NESHAP applies to affected sources of HAP emissions at secondary lead smelters. The 1997 NESHAP (40 CFR 63.542) defines “secondary lead smelters” as “any facility at which lead-bearing scrap material, primarily, but not limited to, lead-acid batteries, is recycled into elemental lead or lead alloys by smelting.” The MACT rule for the Secondary Lead Smelting source category does not apply to primary lead smelters, lead remelters, or lead refiners.

Today, there are 14 secondary lead smelting facilities that are subject to the MACT rule. No new secondary lead smelters have been built in the last 20 years, and we anticipate no new secondary lead smelting facilities in the foreseeable future, although there is one facility currently in the process of expanding operations.

Lead is used to make various construction, medical, industrial and consumer products such as batteries, glass, x-ray protection gear and various fillers. The secondary lead smelting process consists of: (1) Pre-processing of lead bearing materials, (2) melting lead metal and reducing lead compounds to lead metal in the smelting furnace, and (3) refining and alloying the lead to customer specifications.

HAP are emitted from secondary lead smelting as process emissions, process fugitive emissions, and fugitive dust emissions. Process emissions are the exhaust gases from feed dryers and from blast, reverberatory, rotary, and electric furnaces. The HAP in process emissions are primarily composed of metals (mostly lead compounds, but also some arsenic, cadmium, and other metals) and also may include organic compounds that result from incomplete combustion of coke that is charged to the smelting furnaces as a fuel or fluxing agent or from fuel natural gas and/or small amounts of plastics or other materials that get fed into the furnaces along with the lead bearing materials. Process fugitive emissions occur at various points during the smelting process (such as during charging and tapping of furnaces) and are composed primarily of metal HAP. Fugitive dust emissions result from the entrainment of HAP in ambient air due to material handling, vehicle traffic, wind erosion from storage piles, and other various activities. Fugitive dust emissions are composed of metal HAP only.

The MACT rule applies to process emissions from blast, reverberatory, rotary, and electric smelting furnaces, agglomerating furnaces, and dryers; process fugitive emissions from smelting furnace charging points, smelting furnace lead and slag taps, refining kettles, agglomerating furnace product taps, and dryer transition pieces; and fugitive dust emissions sources such as roadways, battery breaking areas, furnace charging and tapping areas, refining and casting areas, and material storage areas. For process sources, the NESHAP specifies numerical emissions limits for lead compounds (as a surrogate for metal HAP) for the following types of smelting furnaces: (1) Collocated reverberatory and blast furnaces (reverberatory/blast), (2) blast furnaces, and (3) reverberatory furnaces not collocated with blast furnaces, rotary furnaces, and electric furnaces. Lead compound emissions from all smelting furnace configurations are limited to an outlet concentration of 2.0 milligrams per dry standard cubic meter (mg/dscm) (0.00087 grains per dry standard cubic foot (gr/dscf)), 40 CFR 63.543(a). Total hydrocarbon (THC) emissions (as a surrogate for organic HAP) from existing and new collocated reverberatory/blast furnace

configurations are limited to an outlet concentration of 20 parts per million volume (ppmv) (expressed as propane) corrected to 4 percent carbon dioxide (CO

) to account for dilution. THC emissions are limited to 360 ppmv (as propane) at 4 percent CO

from existing blast furnaces and 70 ppmv (as propane) at 4 percent CO

from new blast furnaces (40 CFR 63.543(c)). The NESHAP does not specify emissions limits for THC emissions from reverberatory furnaces not collocated with blast furnaces, rotary furnaces, and electric furnaces.

The 1997 NESHAP requires that process fugitive emissions sources be equipped with an enclosure hood meeting minimum face velocity requirements or be located in a total enclosure subject to general ventilation that maintains the building at negative pressure (40 CFR 63.543(b)). Ventilation air from the enclosure hoods and total enclosures is required to be conveyed to a control device. Lead emissions from these control devices are limited to 2.0 mg/dscm (0.00087 gr/dscf) (40 CFR 63.544(c)). Lead emissions for all dryer emissions vents and agglomerating furnace vents are limited to 2.0 mg/dscm (0.00087 gr/dscf) (40 CFR 63.544(d)). The 1997 NESHAP also requires the use of bag leak detection systems (BLDS) for continuous monitoring of baghouses in cases where a high efficiency particulate air (HEPA) filter was not used in series with a baghouse (40 CFR 63.548(c)(9)).

For fugitive dust sources, as defined in 40 CFR 63.545, the 1997 NESHAP requires that the smelting process and all control devices be operated at all times according to a standard operating procedures (SOP) manual developed by the facility. The SOP manual is required to describe, in detail, the measures used to control fugitive dust emissions from plant roadways, battery breaking areas, furnace areas, refining and casting areas, and material storage and handling areas.

B. What data collection activities were conducted to support this action?

In June 2010, EPA issued an information collection request (ICR), pursuant to CAA section 114, to six companies that own and operate the 14 secondary lead smelting facilities. The ICR requested available information regarding process equipment, control devices, point and fugitive emissions, practices used to control fugitive emissions, and other aspects of facility operations. The six companies completed the surveys for their facilities and submitted the responses to us in the fall of 2010. In addition to the ICR survey, each facility was asked to submit reports for any emissions tests conducted in 2003 or later. We received lead emissions test data from all 14 facilities with some facilities submitting data for multiple years. Additionally, EPA requested that eight facilities conduct additional emissions tests in 2010 for certain HAP from specific processes that were considered representative of the industry. Pollutants tested included most HAP metals, dioxins and furans, and certain organic HAP. The results of these tests were submitted to EPA in the fall of 2010 and are available in the docket for this action.

III. Analyses Performed

In this section we describe the analyses performed to support the proposed decisions for the RTR for this source category.

A. Addressing Unregulated Emissions Sources

In the course of evaluating the Secondary Lead Smelting source category, we identified certain HAP for which we failed to establish emission standards in the original MACT. See

National Lime

EPA

, 233 F. 3d 625, 634 (DC Cir. 2000) (EPA has “clear statutory obligation to set emissions standards for each listed HAP”). Specifically, we evaluated emissions standards for three HAP (or groups of HAP), described below, that are not specifically regulated in the existing 1997 MACT standard, or are only regulated for certain emissions points. As described below, for two of these groups of HAP (

i.e.

, organic HAP and dioxins and furans) we are proposing emissions limits pursuant to 112(d)(2) and 112(d)(3). For the other HAP (mercury compounds), we are proposing standards based on work practices pursuant to 112(h). The results and proposed decisions based on the analyses performed pursuant to CAA section 112(d)(2), 112(d)(3), and 112(h) are presented in Section IV.A of this preamble.

1. Organic HAP

EPA did not establish standards for organic HAP emitted from reverberatory furnaces not collocated with blast furnaces, rotary furnaces, and electric furnaces in the 1997 NESHAP. EPA is therefore proposing to set emissions limits for organic HAP emissions from these furnace configurations in today's action based on emissions data received in response to the ICR.

2. Mercury

The 1997 NESHAP specified emissions limits for metal HAP (

e.g.

, arsenic, cadmium, lead) in terms of a lead emissions limit (

i.e.

, lead is used as a surrogate for metal HAP). There is no explicit standard for mercury and we are therefore proposing a standard pursuant to section 112 (as described further in section IV.A of this preamble).

3. Dioxins and Furans

Lastly, with regard to dioxin and furan emissions, because the 1997 NESHAP did not include emissions limits, we are proposing emissions standards for dioxins and furans pursuant to CAA section 112(d)(3). We are also proposing work practices for dioxins and furans.

B. How did we estimate risks posed by the source category?

EPA conducted a risk assessment that provided estimates of the maximum individual cancer risk (MIR) posed by the HAP emissions from the 14 sources in the source category, the distribution of cancer risks within the exposed populations, total cancer incidence, estimates of the maximum target organ-specific hazard index (TOSHI) for chronic exposures to HAP with the potential to cause chronic non-cancer health effects, worst-case screening estimates of hazard quotients (HQ) for acute exposures to HAP with the potential to cause non-cancer health effects, and an evaluation of the potential for adverse environmental effects. In June of 2009, the EPA's Science Advisory Board (SAB) conducted a formal peer review of our risk assessment methodologies in its review of the document entitled, “Risk and Technology Review (RTR) Assessment Methodologies”.

We received the final SAB report on this review in May of 2010.

Where appropriate, we have responded to the key messages from this review in developing the current risk assessment; we will be continuing our efforts to improve our assessments by incorporating updates based on the SAB recommendations as they are developed and become available. The risk assessment consisted of seven primary steps, as discussed below.

U.S. EPA, 2009. Risk and Technology Review (RTR) Risk Assessment Methodologies: For Review by the EPA's Science Advisory Board with Case Studies—MACT I Petroleum Refining Sources and Portland Cement Manufacturing. EPA-452/R-09-006.

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

U.S. EPA, 2010. SAB's Response to EPA's RTR Risk Assessment Methodologies.

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

The docket for this rulemaking contains the following document, which provides more information on the risk

assessment inputs and models: Draft Residual Risk Assessment for the Secondary Lead Smelting Source Category.

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

For each facility in the Secondary Lead Smelting source category, we compiled an emissions profile (including emissions estimates, stack parameters, and location data) based on the information provided by the industry in the ICR, the emissions test data, various calculations, and the NEI. The site-specific emissions profiles include annual estimates of process, process fugitive, and fugitive dust emissions for the 2008-2010 timeframe, as well as emissions release characteristics such as emissions release height, temperature, velocity, and location coordinates.

The primary risk assessment is based on estimates of the actual emissions (though we also analyzed allowable emissions and the potential risks due to allowable emissions). We received a substantial amount of emissions test data and other information that enabled us to derive estimates of stack emissions of certain HAP for all of the facilities. However, we did not have test data for all pollutants at all emissions points. Therefore, we estimated emissions of some pollutants from certain emissions points (for which we had no emissions data) using test data from similar source types with similar controls.

With regard to fugitive emissions, because they cannot be readily captured or directly measured, fugitive emissions are a more challenging emissions type to estimate. In 2010, as part of an information collection request (ICR), EPA asked the Secondary Lead industry to provide their best estimate of the emissions from fugitive sources (

e.g.,

building openings, raw material storage piles, roadways, parking areas) at their facilities and to provide a description of the basis for the estimates (

e.g.,

test data, emissions factors, mass balance calculations, engineering judgment). For our analysis of fugitive emissions for the source category, we first reviewed and evaluated the estimates of fugitive lead emissions that were submitted by each of the facilities in response to the 2010 ICR to determine the reliability and appropriateness of those estimates as an input to our risk analyses and other assessments. We concluded that there were significant gaps and incomplete documentation for a number of facilities, a large amount of variability in estimates between the facilities, and various significant uncertainties. For example, five facilities did not provide any estimates of fugitive emissions, while a few other facilities provided emissions estimates that were quite incomplete. Thus, we developed estimates of fugitive emissions for all facilities in the source category based on a methodology described in the emissions development technical document (

Draft Development of the RTR Emissions Dataset for the Secondary Lead Smelting Source Category

) for this rulemaking, which is available in the docket. In this methodology, we began with estimates provided by one facility in the ICR which were well-documented and covered all the various fugitive emissions sources expected at these facilities. Using the ICR responses, other available information on fugitive emissions (including scientific literature), and various assumptions and calculations, we scaled these estimates to derive site-specific fugitive emissions estimates at each of the other 13 facilities. The estimates calculated using this methodology were used as inputs to the risk assessment modeling.

The results of the risk assessment modeling (which are described further in section IV below) indicated that the fugitive dust emissions were the largest contributor to the risks due to lead emissions. The impacts of fugitive emissions were generally considerably greater than the impacts due to stack emissions. Because of these impacts, and because of the difficulties and uncertainties associated with estimating fugitive emissions, we decided to do further analyses and review of the fugitive emissions estimates as a quality assurance check on the initial fugitive emissions estimates. Therefore, we consulted further with industry representatives, gathered additional information from the EPA's Toxics Release Inventory, evaluated the ICR responses further, and performed various other analyses, which led to the development of an alternative set of fugitive emissions estimates based on a slightly different methodology. The total fugitive estimates of lead for the industry calculated based on the alternative approach are within 10 percent of our initial estimates. We did not rerun the model with the alternative estimates because we know that the overall results would be quite similar and would not change our overall conclusions and decisions (described later in this notice). Further details on all the emissions data, calculations, estimates, and uncertainties, are in the emissions technical document (

Draft Development of the RTR Emissions Dataset for the Secondary Lead Smelting Source Category

) which is available in the docket for this action. We are seeking comments on our emissions data and estimates, and the fugitive emissions estimation methodologies and any other potential appropriate methods or data that could be used to estimate fugitive emissions from these facilities.

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

The emissions data in our data set are estimates of actual emissions on an annual basis for stacks and fugitives for the 2008-2010 timeframe. With most source categories, we generally find that “actual” emissions levels are lower than the emissions levels that a facility is allowed to emit under the MACT standards. The emissions levels allowed to be emitted by the MACT standards are referred to as the “MACT-allowable” emissions levels. This represents the highest emissions level that could be emitted by facilities without violating the MACT standards.

As we have discussed in prior residual risk and technology review rules, assessing the risks at the MACT-allowable level is inherently reasonable since these risks reflect the maximum level at which sources could emit while still complying with the MACT standards. However, 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 emissions standards to provide an operational cushion to accommodate the variability in manufacturing processes and control device performance. Facilities' actual emissions may also be significantly lower than MACT-allowable emissions for other reasons such as State requirements, better performance of control devices than required by the MACT standards, or reduced production.

For the Secondary Lead Smelting source category, we evaluated actual and allowable emissions for both stack emissions and fugitive dust emissions. As described earlier in this section, the actual emissions data for this source category were compiled based on the ICR responses, available test data, various calculations, and the NEI. We estimated actual emissions for all HAP that we identified in the dataset. The

analysis of allowable emissions was largely focused on lead compound emissions, which we considered the most important HAP emitted from this source category based on our screening level risk assessment and the HAP for which we had the most data. However, we also considered allowable emissions for other HAP.

With regard to fugitive emissions, because there are no numerical emissions limits, and because all facilities are required to implement identical fugitive emissions control work-practices, we assume that the allowable fugitive emissions from this source category are equal to the actual emissions.

To estimate emissions at the MACT-allowable level from stacks (

e.g.

, process, process fugitive, and building vents), we estimated the emissions that would occur if facilities were continuously emitting lead at the maximum allowed by the existing MACT standard (

i.e.

, 2.0 mg/dscm) from all vents. We then compared these estimated allowable emissions to the estimated emissions using the actual stack test data for each facility. We realize that these estimates of allowable emissions are theoretical high-end estimates as facilities must maintain average emissions levels at some level below the MACT limit to ensure compliance with the standard at all times because of the day-to-day variability in emissions. Nevertheless, these high-end estimates of allowable emissions were adequate for us to estimate the magnitude of allowable emissions and the differences between the estimates of actual emissions and the MACT allowable emissions.

Based on this analysis, we conclude that all facilities are emitting lead at levels lower than allowable; however, the range of differences between actual and allowable is significant. For two facilities, the estimated actual emissions were only moderately lower than allowable (about 2-3 times lower). The majority of other facilities have estimated actual emissions in the range of 10 to 100 times lower than allowable. Finally, one facility, which has highly advanced controls, has estimated actual emissions of about 1,500 times below the MACT allowable emissions level.

We then developed a ratio of MACT-allowable to actual emissions for each facility in the source category. After developing these ratios, we applied them on a facility-by-facility basis to the maximum modeled ambient lead concentrations to estimate the maximum ambient concentrations that would occur if all stacks were emitting at maximum allowable levels. The ratios were applied to stack emissions while leaving fugitive dust emissions at actual levels since, as described above, actual fugitive dust emissions were assumed to be equal to allowable fugitive dust emissions. The estimates of MACT-allowable emissions are described further in the technical document:

Draft Development of the RTR Emissions Dataset for the Secondary Lead Smelting Source Category

. The estimates of risks due to allowable emissions are summarized in Section IV.B of this preamble and described further in the draft risk report:

Draft Residual Risk Assessment for the Secondary Lead Smelting Source Category

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 the source category 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 based on the year 2000 U.S. Census. In addition, for each census block, the census library includes the elevation and controlling hill height, which are also used in dispersion calculations. A third library of pollutant 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 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 concentrations 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 the facilities as the cancer risk associated with a lifetime (70-year period) of exposure to the maximum concentration at the centroid of inhabited census blocks. Individual cancer risks were calculated by multiplying the estimated lifetime exposure to the ambient concentration of each of the HAP (in micrograms per cubic meter) 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. In general, for residual risk assessments, we 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, if appropriate. For this review, URE values and their sources (

e.g.

, IRIS, CalEPA) can be found in Table 2.6-1(a) in the risk assessment document entitled,

Draft Residual Risk Assessment for the Secondary Lead Smelting Source Category

, which is available in the docket for this proposed rulemaking.

Incremental individual lifetime cancer risks associated with emissions from the 14 facilities in 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 the sources 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 models, including AERMOD.

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 Science Advisory Board (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 the 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 value, which is either the EPA RfC, defined as “an estimate (with uncertainty spanning perhaps an order of magnitude) of a continuous inhalation exposure to the human population (including sensitive subgroups) that is likely to be without an appreciable risk of deleterious effects during a lifetime,” or, in cases where an RfC is not available, the Agency for Toxic Substances and Disease Registry (ATSDR) chronic Minimal Risk Level (MRL) or the CalEPA Chronic Reference Exposure Level (REL). Notably, the REL is defined as “the concentration level at or below which no adverse health effects are anticipated for a specified exposure duration.”

Worst-case 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 was located at this spot at a time when both the peak (hourly) emissions rate and worst-case hourly dispersion conditions occurred. In general, acute HQ values were calculated using best available, short-term dose-response values. These acute dose-response values include REL, Acute Exposure Guideline Levels (AEGL), and Emergency Response Planning Guidelines (ERPG) for 1-hour exposure durations. Notably, for HAP emitted from this source category, REL values were the only such dose-response values available. As discussed below, we used conservative assumptions for emissions 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.” 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 does not automatically indicate an adverse health impact.

To develop screening estimates of acute exposures, we first developed estimates of maximum hourly emissions rates by multiplying the average actual annual hourly emissions 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 emissions events, in a heavily-industrialized 4-county area (Harris, Galveston, Chambers, and Brazoria Counties, Texas) were less than twice the annual average hourly emissions rate. The highest peak emissions event was 74 times the annual average hourly emissions rate, and the 99th percentile ratio of peak hourly emissions rate to the annual average hourly emissions rate was 9.

This analysis is provided in Appendix 4 of the

Draft Residual Risk Assessment for Secondary Lead Smelting

that is available in the docket for this action. Considering this analysis, unless specific process knowledge or data are available to provide an alternate value, to account for more than 99 percent of the peak hourly emissions, we generally apply the assumption to most source categories that the maximum one-hour emissions rate from any source other than those resulting in fugitive dust emissions are 10 times the average annual hourly emissions rate for that source. We use a factor other than 10 in some cases if we have information that indicates that a different factor is appropriate for a particular source category. Moreover, the factor of 10 is not applied to fugitive dust sources because these emissions are minimized during the meteorological conditions associated with the worst-case short-term impacts (

i.e.

, during low-wind, stable atmospheric conditions) 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 worst-case 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 any worst-case 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. 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 emissions 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 (

i.e.

, factor of 10) approach in our screening analysis. In the case of this source category, we had no further information on peak-to-mean emissions which could be used to refine the estimates. The only refinement that was made to the acute screening assessments was to ensure that the estimated worst-case HQ was not calculated at a location within the facility boundaries.

4. Conducting Multipathway Exposure and Risk Modeling

EPA evaluated 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 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

Emissions of five PB-HAP were identified in the emissions dataset for the Secondary Lead Smelting source category, as follows: Lead compounds, cadmium compounds, POM, dioxin and furans, and mercury.

The dataset is described in the emissions technical document (

Draft Development of the RTR Emissions Dataset for the Secondary Lead Smelting Source Category

) which is available in the docket for this action. As described in that document, lead emissions estimates are based on multiple emission stack tests conducted over multiple years, cadmium and dioxin and furans are based on emissions tests conducted in 2010. Mercury emissions estimates are based on test results in 2010 which included a large number of non-detects and conservative assumptions about non-detects, and the estimates for POM are based on reported estimates from the NEI or estimates provided by the companies in the ICR responses in 2010.

Most of the emissions test results for mercury emissions for this industry were below detection limit. The emissions estimates used in the risk assessment are based on the assumption that all the non-detect test values were at the level of the detection limit. Therefore, these estimated emissions for mercury are clear overestimates. We conclude that the true amounts of emissions of mercury from this source category are much lower than shown in this assessment, but we are not able to quantify precisely how much lower.

Emissions of cadmium compounds, POM, dioxin and furans and mercury were evaluated for potential non-inhalation risks and adverse environmental impacts using our recently developed screening scenario that was developed for use with the Total Risk Integrated Methodology (TRIM.FaTE) model. This screening scenario uses environmental media outputs from the peer-reviewed TRIM.FaTE to estimate the maximum potential ingestion risks for any specified emissions scenario by using a generic farming/fishing exposure scenario that simulates a subsistence environment. The screening scenario retains many of the ingestion and scenario inputs developed for EPA's Human Health Risk Assessment Protocols (HHRAP) for hazardous waste combustion facilities. In the development of the screening scenario, a sensitivity analysis was conducted to ensure that its key design parameters were established such that environmental media concentrations were not underestimated, and to also minimize the occurrence of false positives for human health endpoints. See Appendix 3 of the risk assessment document for a complete discussion of the development and testing of the screening scenario, as well as for the values of facility-level

de minimis

emissions rates developed for screening potentially significant multipathway impacts. For the purpose of developing

de minimis

emissions rates for our multipathway screening, we derived emissions levels at which the maximum human health risk could be 1-in-1 million for lifetime cancer risk, or exposures could potentially be above the reference dose for non-cancer effects, based on a conservative model plant analysis described in Appendix 3 of the risk assessment document.

For the secondary lead smelting source category, there were exceedances of

de minimis

emissions rates at multiple facilities for multiple PB-HAP, and thus a multipathway analysis was performed. Two facilities were chosen as case study analyses to assess potential multipathway risks for mercury, cadmium, POM, and dioxins and furans. The selection criteria for modeling these two facilities included emissions rates of PB-HAPs, proximity to water bodies, proximity to farmland, average rainfall, average wind speed and direction, smelting furnace type, local change in elevation, and geographic representativeness of sites throughout the U.S. As a result of our selection process, we believe the multipathway risks associated with these two facilities are in the upper end of the potential for multipathway risks from the source category. Since the modeling used in these case study assessments utilize site specific parameters to describe naturally occurring physical, chemical and biological processes, we believe that the multimedia concentrations of PB-HAPs generated in this analysis are unbiased estimates of the true impacts.

In general, results of this assessment were designed to characterize multipathway risks associated with high end consumption of PB-HAP predominantly from contaminated food sources. Thus, multipathway exposure and risk estimates were calculated for two basic scenarios, both of which are expected to give rise to high-end exposures and risks. The farmer scenario involves an individual living on a farm homestead in the vicinity of a PB-HAP source who consumes contaminated produce grown on the farm, as well as contaminated meat and animal products raised on the farm. The farming scenario also accounts for incidental ingestion of contaminated surface soil at the location of the farm homestead. The recreational fisher scenario involves an individual who regularly consumes fish caught in freshwater lakes in the vicinity of a PB-HAP source. In the fishing scenario, in addition to the characterization of exposure and risks across the broad population of recreational anglers, exposures were also calculated for three subpopulations of recreational anglers (Hispanic, Laotian, and Vietnamese descent) who have higher rates of fish consumption.

Furthermore, in order to more fully characterize the modeled potential multipathway risks that may be associated with high-end consumption of PB-HAP contaminated food, we present results based on two ingestion exposure scenarios: (1) A reasonable maximum exposure (RME) scenario that, for example, utilizes 90th percentile ingestion rates for farmers, recreational anglers, and the three subpopulations of recreational anglers (

e.g.,

ingestion rates specific to Laotian recreational anglers); and (2) a central tendency exposure (CTE) scenario that, for example, utilizes mean ingestion rates for the groups just described. We provide results from both scenarios to illustrate the range of potential modeled exposures and risks that may exist in the high-end of the complete distribution of potential multipathway risks for this source category.

In both scenarios, exposure via drinking water was not considered because it is unlikely that humans would use surface waters as a drinking water source. Groundwater, which is a likely source of drinking water, also was not included in the exposure scenarios because contamination of groundwater aquifers by air deposition sources was not expected to be significant. For dioxin, exposure via breast milk was considered in the farming scenario as well as the recreational fishing scenario, but not for the three recreational fishing subpopulations (Hispanic, Laotian, and Vietnamese descent) since subpopulation ingestion rates were only applicable to adult males. The breast milk pathway was not considered with respect to mercury exposure due to a current lack of data regarding this pathway.

In evaluating the potential air-related multipathway risks from the emissions of lead compounds, rather than developing a

de minimis

emissions rate, we compared its maximum modeled 3-month average atmospheric lead concentration at any off-site location with the current primary National Ambient Air Quality Standard (NAAQS) for lead (promulgated in 2008), which is set at a level of 0.15 micrograms per cubic meter (µg/m

) based on rolling 3-month periods with a not-to-be-exceeded level for any 3-month rolling average, and which will require attainment by 2016 (73 FR 66964). Notably, in making these comparisons, we estimated maximum rolling 3-month ambient lead concentrations taking into account all of the elements of the NAAQS for lead. That is, our estimated 3-month lead concentrations are

calculated in a manner that is consistent with the indicator, averaging time, and form of the lead NAAQS, and those estimates are compared to the level of the lead NAAQS (0.15 µg/m

The NAAQS value, a public health policy judgment, incorporated the Agency's most recent health evaluation of air effects of lead exposure for the purposes of setting a national standard. In setting this value, the Administrator promulgated a standard that was requisite to protect public health with an adequate margin of safety. That standard applies everywhere, under all circumstances, regardless of an individual's location, exposure patterns, or health circumstances. We consider values below the level of the primary NAAQS to protect against multipathway risks because, as mentioned above, the primary NAAQS is set so as to protect public health with an adequate margin of safety. However, ambient air lead concentrations above the NAAQS are considered to pose the potential for increased risk to public health. We consider this assessment—comparing modeled concentrations to the level of the NAAQS—to be a refined analysis given: (1) The numerous health studies, detailed risk and exposure analyses, and level of external peer and public review that went into the development of the primary NAAQS for lead, combined with: (2) the site-specific dispersion modeling performed in the risk assessment to develop ambient concentration estimates from the 14 secondary lead smelter facilities addressed in this proposed rule. It should be noted, however, that this comparison to the NAAQS for lead does not account for possible population exposures to lead from sources other than the one being modeled; for example, via consumption of water from contaminated local sources or ingestion of contaminated locally grown food. Nevertheless, the Administrator judged that the primary NAAQS would protect, with an adequate margin of safety, the health of children and other at-risk populations against an array of adverse health effects, most notably including neurological effects, particularly neurobehavioral and neurocognitive effects, in children (73 FR 67007). The Administrator, in setting the standard, also recognized that no evidence of a risk-based bright line indicated a single appropriate level. Instead, a collection of scientific evidence and other information was used to select the standard from a range of reasonable values (73 FR 67006).

We further note that comparing ambient lead concentrations to the NAAQS for lead, considering the level, averaging time, form and indicator of the lead NAAQS, also informs whether there is the potential for adverse environmental effects. This is because the secondary lead NAAQS, which has the same averaging time, form, and level as the primary standard, was set to protect the public welfare which includes among other things soils, water, crops, vegetation and wildlife (CAA section 302(h)). Thus, ambient lead concentrations above the NAAQS for lead also indicate the potential for adverse environmental effects (73 FR 67007 to 67012). For additional information on the multipathway analysis approach, see the residual risk documentation as referenced in Section III.A of this preamble. EPA solicits comment generally on the modeling approach used herein to assess air-related lead risks, and specifically on the use of the lead NAAQS in this analytical construct.

5. Assessing Risks Considering Emissions Control Options

In addition to assessing baseline inhalation risks and screening for potential multipathway risks, we also estimated risks considering the potential emissions reductions that would be achieved by the main control options under consideration. The expected emissions reductions were applied to the specific HAP and emissions points in the source category dataset to develop corresponding estimates of risk reductions. More information regarding the risks after control can be found in the risk assessment document:

Draft Residual Risk Assessment for the Secondary Lead Smelting Source Category,

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, for our residual risk review, we also examine the risks from the entire “facility,” where the facility includes all HAP-emitting operations within a contiguous area and under common control. In other words, we examine the HAP emissions not only from the source category of interest, but also emissions of HAP from all other emissions sources at the facility. In this rulemaking, for the Secondary Lead Smelting source category, there are no other significant HAP emissions sources present. Thus, there was no need to perform a separate facility wide risk assessment.

b. Demographic Analysis

To identify specific groups that may be affected by this rulemaking, EPA conducted demographic analyses. These analyses provide information about the percentages of different social, demographic, and economic groups within the populations subjected to potential HAP-related cancer and non-cancer risks from the facilities in this source category.

For the demographic analyses, we focus on the populations within 50 km of any facility with emissions sources subject to the MACT standard (identical to the risk assessment). Based on the emissions for the source category or the facility, we then identified the populations that are estimated to have exposures to HAP which result in: (1) Cancer risks of 1-in-1 million or greater; (2) non-cancer HI of 1 or greater; and/or (3) ambient lead concentrations above the level of the NAAQS for lead. We compare the percentages of particular demographic groups within the focused populations to the total percentages of those demographic groups nationwide. The results, including other risk metrics, such as average risks for the exposed populations, are documented in a technical report in the docket for the source category covered in this proposal.

Risk and Technology Review—Analysis of Socio-Economic Factors for Populations Living Near Primary Lead Smelting Operations.

The basis for the risk estimates used in the demographic analyses for this source category was the modeling results based on actual emissions levels obtained from the HEM-3 model described above. The risk estimates 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 were 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 census block level, the age and income census data are only available at the census block group 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 census blocks within the block group have the same distribution of ages and incomes as the block group.

As noted above, we focused the analysis on those census blocks where source category risk results show: (1) Estimated lifetime inhalation cancer risks above 1-in-1 million; (2) chronic non-cancer indices above 1; and/or (3) census blocks where estimated ambient lead concentrations were above the level of the lead NAAQS. For each of these cases, we determined the relative percentage of 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 people living below the poverty line within those census blocks.

The specific census population categories included:

• Total population

• White

• African American (or Black)

• Native Americans

• Other races and multiracial

• Hispanic or Latino

• People living below the poverty line

• 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.

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 “Minorities,” a classification that is defined for these purposes as all race population categories except white.

The methodology and the results of the demographic analyses for this source category are included in the technical report available in the docket for this action (

Risk and Technology Review—Analysis of Socio-Economic Factors for Populations Living near Secondary Lead Smelting Operations

7. Considering Uncertainties in Risk Assessment

Uncertainty and the potential for bias are inherent in all risk assessments, including those performed for the source category addressed in this proposal. Although uncertainty exists, we believe the approach that we took, which used conservative tools and assumptions to bridge data gaps, ensures that our decisions are health-protective. A brief discussion of the uncertainties in the emissions dataset, dispersion modeling, inhalation exposure estimates, dose-response relationships, multipathway and environmental impacts analyses, and demographics analysis follows below. A more thorough discussion of these uncertainties is included in the risk assessment documentation (

Draft Residual Risk Assessment for the Secondary Lead Smelting Category

) available in the docket for this action.

a. Uncertainties in the Emissions Dataset

Although the development of the RTR dataset involved quality assurance/quality control processes, the accuracy of emissions values will vary depending on the source of the data, the degree to which data are incomplete or missing, the degree to which assumptions made to complete the datasets are accurate, whether and to what extent errors were made in estimating emissions values, and other factors. The estimates of stack emissions are largely based on actual emissions test data, and, therefore, we have a relatively high degree of confidence in those estimates. With regard to fugitive emissions, those estimates are largely based on engineering calculations and application of various assumptions, and are therefore considered less certain relative to the stack emissions estimates. Nevertheless, we believe the fugitive estimates we derived for these facilities and used in our analyses are reasonable estimates of the actual fugitive emissions from these facilities partly due to the findings that the available ambient monitoring data (which are described in the document

Draft Summary of the Ambient Lead Monitoring Data near Secondary Lead Smelting Facilities,

available in the docket) indicate that measured levels of lead in ambient air near these facilities are generally similar in magnitude (

e.g.,

generally within a factor of 2) to the modeled estimates (which are shown in the

Draft Residual Risk Assessment for the Secondary Lead Smelting Source Category,

which is available in the docket).

The emissions estimates for stacks considered in this analysis are hourly emissions rates primarily extracted from test reports and extrapolated to an annual total based on the hours of operation of each facility and may not reflect short-term fluctuations during the course of a year or variations from year to year. The estimates of peak hourly emissions rates from stacks for the acute effects screening assessment were based on multiplication factors applied to the hourly emissions rates (the default factor of 10 was used for Secondary Lead Smelting for sources other than fugitive dust) which are intended to account for emissions fluctuations due to normal facility operations.

There is an unquantified level of uncertainty regarding the emissions estimates for acute impacts of fugitive dusts. The current set of assumptions used in deriving the worst-case acute impact estimate for fugitive dusts assumes the average hourly emission level (annual emissions divided by 8760 hours per year) to occur at the default worst-case meteorological conditions (low winds with a stable atmosphere). It is acknowledged that the combination of average emissions during low winds would be an overestimate of the fugitive dust emission rate during those low wind periods. Therefore, for fugitive dusts, the worst case meteorology may not be the same as for other process emissions, and the level of hourly fugitive dust emissions during this alternate worst-case condition is unknown.

We further note that there is additional uncertainty with respect to emissions of mercury. As previously noted, most of the mercury emissions test results for this industry were below detection limit. The emissions estimates utilized in the risk assessment are based on the health-protective assumption that all the non-detect test values were at the level of the detection limit. Therefore, these estimated emissions for mercury are clear overestimates. We conclude that the true amounts of emissions of mercury from this source category are much lower than those provided in the technical documents supporting today's proposed rule, but we are not able to quantify precisely how much lower.

b. Uncertainties in Dispersion Modeling

Although 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. In circumstances where we had to choose between various model options, where possible, we selected model options (

e.g.,

rural/urban, plume depletion, chemistry) that provided an overestimate of ambient concentrations of the HAP rather than an underestimate. However, because of practicality and data limitation reasons, some factors (

e.g.,

building downwash) have the potential in some situations to overestimate or underestimate ambient impacts. 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.

Furthermore, as noted previously, there is a level of uncertainty in the

conditions leading to worst-case emissions for fugitive dusts. However, in the absence of better information regarding actual short-term impacts from fugitive dust sources, the combination of average hourly emission level and worst-case meteorology was assumed to be useful for deriving protective acute impact estimates.

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 farther 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 for any one individual, 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 projected 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 future risks posed by a given source or source category. Depending on the characteristics of the industry, these factors will, in most cases, result in an overestimate both in individual risk levels and in the total estimated number of cancer cases. However, in rare cases, where a facility maintains or increases its emissions levels beyond 70 years, residents live beyond 70 years at the same location, and the residents spend most of their days at that location, then the risks could potentially be underestimated. 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 of the 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 for some HAP.

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 be worst-case 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 dose-response 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 variability in dose-response relationships is given in the residual risk documentation 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 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 a continuous inhalation exposure (RfC) or a daily oral exposure (RfD) 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 considers uncertainty, variability and gaps in the available data. The UF are applied to derive reference values that are intended to protect against appreciable risk of deleterious effects. The 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 observed adverse effect (exposure) level to no observed adverse 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).

As further discussed below, there is no RfD or other comparable chronic health benchmark value for lead compounds. Thus, to address multipathway human health and environmental risks associated with emissions of lead from this facility, ambient lead concentrations were compared to the NAAQS for lead. In developing the NAAQS for lead, EPA considered human health evidence reporting adverse health effects associated with lead exposure, as well as an EPA-conducted multipathway risk assessment that applied models to estimate human exposures to air-related lead and the associated risk (73 FR 66979). EPA also explicitly considered the uncertainties associated with both the human health evidence and the exposure and risk analyses when developing the NAAQS for lead. For example, EPA considered uncertainties in the relationship between ambient air lead and blood lead levels (73 FR 66974), as well as uncertainties between blood lead levels and loss of IQ points in children (73 FR 66981).

In considering the evidence and risk analyses and their associated uncertainties, EPA found that there is no evidence- or risk-based bright line that indicates a single appropriate level. EPA noted there is a collection of scientific evidence and judgments and other information, including information about the uncertainties inherent in many relevant factors, which needs to be considered together in making the public health policy judgment and in selecting a standard level from a range of reasonable values (73 FR 66998). In so doing, EPA decided that a level for the primary lead standard of 0.15 μg/m

, in combination with the specified choice of indicator, averaging time, and form, is requisite to protect public health, including the health of sensitive groups, with an adequate margin of safety (73 FR 67006). A thorough discussion of the health evidence, risk and exposure analyses, and their associated uncertainties can be found in EPA's final rule revising the lead NAAQS (73 FR 66970-66981, November 12, 2008).

We also note the uncertainties associated with the health-based (

i.e.,

primary) NAAQS are likely less than the uncertainties associated with dose-response values developed for many of the other HAP, particularly those HAP for which no human health data exist.

We also note that because of the multipathway, multi-media impacts of lead, the risk assessment supporting the NAAQS considered direct inhalation exposures and indirect air-related multipathway exposures from industrial sources like primary and secondary lead smelting operations. It also considered background lead exposures from other sources (like contaminated drinking water and exposure to lead-based paints). In revising the NAAQS for lead, EPA placed more weight on the evidence-based framework and less weight on the results from the risk assessment, although the risk estimates were found to be roughly consistent with and generally supportive of the evidence-based framework applied in the NAAQS determination (73 FR 67004). Thus, when revising the NAAQS for lead to protect public health with an adequate margin of safety, EPA considered both the health evidence and the risk assessment, albeit to different extents.

In addition to the uncertainties discussed above with respect to chronic, cancer, and the lead NAAQS reference values, there are also uncertainties associated with acute reference values. 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 short-term dose-response 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 hazardous air pollutants continue to 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 (

e.g.,

cadmium and nickel), 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 or overstate human health risk.

e. Uncertainties in the Multipathway and Environmental Impacts Assessment

For the secondary lead smelting source category, two facilities were chosen as case study analyses to assess potential multipathway risks for mercury, cadmium, POM, and dioxins and furans. The selection criteria for modeling these two facilities included emissions rates of PB-HAPs, proximity to water bodies, proximity to farmland, average rainfall, average wind speed and direction, smelting furnace type, local change in elevation, and geographic representativeness of sites throughout the U.S. However, there is uncertainty as to whether these two facilities represent the highest potential for multipathway human health risks from the source category.

Since the modeling used in these case study assessments utilize site specific parameters to describe naturally occurring physical, chemical and biological processes, we believe that the multimedia concentrations of PB-HAPs generated in this analysis are unbiased estimates of the true impacts.

With respect to the risk estimates generated from this analysis, we present results based on two ingestion exposure scenarios: the RME and CTE scenarios. As noted above, we believe that these scenarios illustrate the range of potential modeled exposures and risks that may exist in the high-end of the complete distribution of potential multipathway risks for this source category.

We further note that high-end fisher populations could display considerable variability both in terms of the degree to which they frequent specific water bodies or watersheds and the degree to which they target specific types of fish (or at least sizes of fish). Both of these factors can impact estimates of exposure. If a fisher population distributes their activity across a range of water bodies and harvests a variety of fish species (and sizes) than the distribution of exposure and risk across that population will be smaller compared with a population that focuses activity at individual water bodies and tends to focus on larger fish.

To estimate potential high-end multipathway exposures and risks, in addition to utilizing fish consumption rate data for the general U.S. population of recreational anglers,

we used fish consumption information for distinct fisher subpopulations that are known to have higher fish consumption rates. The data were obtained from Shilling,

et al.

(2010).

In this publication, the authors provide fish consumption information for different ethnic groups including Hispanics, Laotians, and Vietnamese surveyed in California's Central Valley Delta based on sample sizes of 45, 33, and 30, respectively. We note that there is uncertainty based on the limited sample sizes and in the extrapolation of these fish consumption rates to other parts of the United States. Further discussion of these values is provided in the risk assessment supporting documents. We request comment on the use of these data to support the RME analysis.

Data for the general U.S. population of recreational anglers was obtained from: EPA 2002, “Estimated Per Capita Fish Consumption in the United States, Office of Water, Office of Science and Technology, Washington, DC, EPA-821-C-02-003. August 2002.

Shilling,

et al.

2010 is available in the docket for this rulemaking.

A more detailed discussion of the multipathway analysis and its associated uncertainties is presented in section 5.3 of the document Human Health Multipathway Residual Risk Assessment for the Secondary Lead Smelting Source Category, which can be found in the docket for the proposed rule.

f. Uncertainties in the Demographic Analysis

Our analysis of the distribution of risks across various demographic groups is subject to uncertainty associated with the extrapolation of census-block group data (

e.g.,

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

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

In evaluating and developing standards under section 112(f)(2), as discussed in Section I.A of this preamble, we apply a two-step process to address residual risk. In the first step, EPA determines whether risks are acceptable. This determination “considers all health information, including risk estimation uncertainty, and includes a presumptive limit on maximum individual lifetime [cancer] risk (MIR)

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 actions, EPA has presented and considered 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 (72 FR 25138, May 3, 2007; 71 FR 42724, July 27, 2006). In our most recent proposals (75 FR 65068, October 21, 2010 and 75 FR 80220, December 21, 2010), EPA also presented and considered additional measures of health information, such as estimates of the risks associated with the maximum level of emissions which might be allowed by the current MACT standards (see,

e.g.,

75 FR 65068, October 21, 2010 and 75 FR 80220, December 21, 2010). EPA also discussed and considered risk estimation uncertainties. EPA is providing this same type of information in support of the proposed actions described in this

Federal Register

notice.

The Agency is considering all 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 [previous] section 112 is best judged on the basis of a broad set of health risk measures and information” (54 FR 38046). Similarly, with regard to making the ample margin of safety determination, as stated in the Benzene NESHAP “[in the ample margin decision, the Agency again considers all of the health risk and other health information considered in the first step. Beyond that information, additional factors relating to the appropriate level of control will also be considered, including cost and economic impacts of controls, technological feasibility, uncertainties, and any other relevant factors.”

Id.

The Agency acknowledges that the Benzene NESHAP provides flexibility regarding what factors EPA might consider in making determinations and how these factors 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 at 38057).

Thus, the level of the MIR is only one factor to be weighed in determining acceptability of risks. The Benzene NESHAP explained that “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, EPA stated in the Benzene NESHAP that: “* * * EPA believes the relative weight of the many factors that can be considered in selecting an ample margin of safety can only be determined for each specific source category. This occurs mainly because technological and economic factors (along with the health-related factors) vary from source category to source category” (

Id.

at 38061).

EPA wishes to point out that certain health information has not been considered to date in making residual risk determinations. 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 generally we have also assessed risks due to HAP emissions from the entire facility at which the covered source category is located (facility-wide risk estimates). We have not attempted to characterize the risks associated with all HAP emissions impacting the populations living near the sources in these categories. That is, at this time, we do not attempt to quantify those HAP risks that may be associated with emissions from other facilities that do not include the source categories in question, mobile source emissions, natural source emissions, persistent environmental pollution, or atmospheric transformation in the vicinity of the sources in these categories.

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 health reference levels (

e.g.,

Reference Concentrations (RfCs)) 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 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.

Although 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, and hence would compound 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 comments and recommendations for any other comparative measures that may be useful in the assessment of the distribution of HAP risks across potentially affected demographic groups.

D. How did we perform the technology review?

Our technology review focused on the identification and evaluation of developments in practices, processes, and control technologies that have occurred since the 1997 NESHAP was promulgated. In cases where the technology review identified such developments, we conducted an analysis of the technical feasibility of applying these developments, along with the estimated impacts (costs, emissions reductions, risk reductions,

etc.

) of applying these developments. We then made decisions on whether it is necessary to propose amendments to the regulation to require any of the identified developments.

Based on our analyses of the data and information collected by the ICR and our general understanding of the industry and other available information on potential controls for this industry, we identified several potential 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 development of the 1997 NESHAP.

• Any improvements in add-on control technology or other equipment (that were identified and considered during development of the 1997

NESHAP) that could result in significant additional emissions reduction.

• Any work practice or operational procedure that was not identified or considered during development of the 1997 NESHAP.

• Any process change or pollution prevention alternative that could be broadly applied to the industry and that was not identified or considered during development of the 1997 NESHAP.

In addition to reviewing the practices, processes, or control technologies that were not considered at the time we developed the 1997 NESHAP, we reviewed a variety of data sources in our evaluation of whether there were additional practices, processes, or controls to consider for the secondary lead smelting industry. Among the data sources we reviewed were the NESHAP for various industries that were promulgated after the 1997 NESHAP. We reviewed the regulatory requirements and/or technical analyses associated with these regulatory actions to identify any practices, processes, and control technologies considered in these efforts that could possibly be applied to emissions sources in the Secondary Lead Smelting source category, as well as the costs, non-air impacts, and energy implications associated with the use of these technologies.

We also consulted EPA's RACT/BACT/LAER Clearinghouse (RBLC) to identify potential technology advances. Control technologies, classified as RACT (Reasonably Available Control Technology), BACT (Best Available Control Technology), or LAER (Lowest Achievable Emissions 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 database 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 emissions streams. We searched this database to determine whether it contained any practices, processes, or control technologies for the types of processes covered by the Secondary Lead Smelting MACT.

Additionally, we requested information from facilities 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.

E. What other issues are we addressing in this proposal?

In addition to the analyses described above, we also reviewed other aspects of the MACT standards for possible revision as appropriate and necessary. Based on this review we have identified aspects of the MACT standards that we believe need revision.

This includes proposing revisions to the startup, shutdown, and malfunction (SSM) provisions of the MACT rule in order to ensure that they are consistent with a recent court decision in

Sierra Club

EPA

, 551 F.3d 1019 (DC Cir. 2008). In addition, we are proposing other various minor changes with regards to editorial errors and other revisions to promote the use of plain language. The analyses and proposed decisions for these actions are presented in Section IV.E of this preamble.

IV. Analyses Results and Proposed Decisions

This section of the preamble provides the results of our RTR for the Secondary Lead Smelting source category and our proposed decisions concerning changes to the 1997 NESHAP.

A. What are the results of our analyses and proposed decisions regarding unregulated emissions sources?

1. Organic HAP

As discussed in Section III.A of this preamble, we evaluated emissions limits for organic HAP for reverberatory furnaces not collocated with blast furnaces, rotary furnaces, and electric furnaces. Section 112(d)(3)(B) of the CAA requires that the MACT standards for existing sources be at least as stringent as the average emissions limitation achieved by the best performing five sources (for which the Administrator has or could reasonably obtain emissions information) in a category with fewer than 30 sources. The Secondary Lead Smelting source category consists of fewer than 30 sources. Where, as here, there are less than 30 sources, we base the MACT floor limit on the average emissions limitation achieved by those sources for which we have data.

EPA must exercise its judgment, based on an evaluation of the relevant factors and available data, to determine the level of emissions control that has been achieved by the best performing sources under variable conditions. It is recognized in the case law that EPA may consider variability in estimating the degree of emissions reduction achieved by best-performing sources and in setting MACT floors. See

Mossville Envt'l Action Now

EPA

, 370 F.3d 1232, 1241-42 (DC Cir 2004) (holding EPA may consider emissions variability in estimating performance achieved by best-performing sources and may set the floor at a level that a best-performing source can expect to meet “every day and under all operating conditions”). More details on how we calculate MACT floors and how we account for variability are described in the

Draft MACT Floor Analysis for the Secondary Lead Smelting Source Category

which is available in the docket for this proposed action.

With regard to the evaluation of potential MACT limits for organic HAP from this source category, consistent with the explanation presented in the proposal of the 1997 NESHAP (NESHAP for Secondary Lead Smelting, Proposed Rule, June 9, 1994, 59 FR 63941) for this source category describing the appropriateness of THC as a surrogate for organic HAP, we continue to consider THC as an appropriate surrogate for non-dioxin organic HAP in the proposed amendments to the NESHAP in today's action. Based on our data, there are currently only two reverberatory furnaces not collocated with a blast furnace, one rotary furnace, and two reverberatory furnaces mixed with electric furnaces (

i.e.

, two reverberatory furnaces whose exhaust are mixed with the exhaust of an electric furnace prior to atmospheric release) operating in this source category. Based on analysis of emissions data and furnace operating characteristics (as discussed further below), we believe it is appropriate to set one THC limit that will apply to reverberatory furnaces not collocated with a blast furnace and reverberatory furnaces mixed with electric furnaces, because of generally similar (and low) potential for organic HAP emissions from both furnace types. We are proposing a separate THC emissions limit for rotary furnaces.

We received THC emissions data for one reverberatory furnace not collocated with a blast furnace and one reverberatory furnace mixed with an electric furnace, and one rotary furnace. Therefore, for each of these furnace configurations, we have emissions data from at least half the units. We are soliciting emissions data for the

operating affected sources for which we don't have data. Based on the data that we have, we conducted a MACT Floor analysis.

As discussed above, the MACT floor limit is calculated based on the average performance of the units plus an amount to account for these units' variability. To account for variability in the operation and emissions, the stack test data were used to calculate the 99 percent upper predictive limit (UPL) for reverberatory furnaces not collocated with a blast furnace and reverberatory furnaces mixed with electric furnaces. For rotary furnaces, because we have only one test with two successful test runs, we considered both the 99 percent UPL and the 99 percent upper limit (UL) to account for variability in the emissions data. Our consideration of variability is explained in more detail in the technical document for this action:

Draft MACT Floor Analysis for the Secondary Lead Smelting Source Category, which is available in the docket for this action.

The 99 percent UPL for exhaust THC concentrations from existing reverberatory furnaces not collocated with a blast furnace and reverberatory furnaces mixed with electric furnaces is 12 ppmv (expressed as propane) corrected to 4 percent CO

to account for dilution. Consistent with CAA section 112(d)(3), the MACT floor for new sources cannot be less stringent than the emissions control that is achieved in practice by the best-controlled similar source. The 99 percent UPL for exhaust THC concentrations from the best-performing affected source was calculated as 12 ppmv (expressed as propane) corrected to 4 percent CO

We are also proposing a THC MACT limit for rotary furnaces. As mentioned previously, there is only one operating rotary furnace in the U.S. We received test data for this unit; however, it included only two successful test runs. The average of the two emissions test runs was 257 ppmv (expressed as propane and adjusted to 4 percent CO

), and the highest of the two test runs was 292 ppmv (expressed as propane and adjusted to 4 percent CO

). Using the 99 percent UPL approach, we calculated a MACT floor of 1700 ppmv, which is 6.6 times higher than the average. By using the 99 percent UL approach, we calculated a MACT floor of 610 ppmv (expressed as propane and adjusted to 4 percent CO

) applicable to new and existing affected sources, which is 2.4 times higher than the average. Because of very limited emissions data, our statistical analysis does not clearly indicate whether the UPL or UL is a better measure of the typical variability in performance of the unit. However, because the 99 percent UL approach resulted in a MACT floor that is more within the range of typical variability we expect when calculating MACT floors for various source categories and emissions points, the emissions limit calculated using the 99 percent UL was chosen as the proposed THC MACT floor for rotary furnaces in this action. However, we seek comments on this issue.

We considered beyond-the-floor options for THC standards for all of these furnace configurations, as required by section 112(d)(2) of the Act. However, we decided not to propose any limits based on the beyond the floor analyses for THC because of the costs, potential disadvantages of these additional controls (including increases in CO

and NO

emissions), and non-air environmental impacts and adverse energy implications associated with use of these additional controls. The beyond-the-floor analysis is presented in the technical documentation for this action (

Draft MACT Floor Analysis for the Secondary Lead Smelting Source Category

). In summary, we are proposing that new and existing reverberatory furnaces not collocated with a blast furnace and reverberatory furnaces mixed with electric furnaces be subject to a THC concentration limit of 12 ppmv (expressed as propane) corrected to 4 percent CO

. Additionally, we are proposing that both new and existing rotary furnaces be subject to a THC concentration limit of 610 ppmv (expressed as propane) corrected to 4 percent CO

We propose that compliance with all the proposed THC limits will be demonstrated by annual performance tests, and that continuous monitoring of temperatures of control devices (

e.g.

, afterburners) and/or furnaces (

e.g.

, reverberatory furnaces) will be required as parametric monitoring to ensure continuous compliance with the THC limits.

No changes are being considered in this action for the THC limits for blast and collocated blast and reverberatory furnaces established in the 1997 NESHAP.

2. Dioxin and Furans

As mentioned previously, the 1997 NESHAP does not include emissions limits for dioxins and furans. Therefore, pursuant to CAA section 112(d)(3), we are proposing to revise the 1997 NESHAP to include emission limits for dioxins and furans. The form of these proposed standards are in the form of toxic equivalency quotient (TEQ) concentration limits (

i.e.

, prorating the amount of total dioxins and furans allowed to the most toxic species of dioxin). For more information on the TEQ approach to calculating dioxin and furan emissions see the dioxin emissions guidance available at:

http://www.epa.gov/raf/hhtefguidance/.

Because the formation of dioxins and furans is highly temperature dependent, and because the potential for dioxin and furan emissions varies considerably among different furnace types and configurations, EPA is proposing separate limits for each of the following furnace configurations: (1) Reverberatory furnaces not collocated with blast furnaces and reverberatory furnaces where the exhaust gases are mixed with the exhaust from electric furnaces; (2) blast furnaces; (3) collocated blast and reverberatory furnaces; and (4) rotary furnaces. A detailed analysis and documentation of the MACT floor calculations can be found in the technical document for this action:

Draft MACT Floor Analysis for the Secondary Lead Smelting Source Category.

Based on the emissions data and furnace operating temperatures reported in ICR surveys, EPA is proposing a single TEQ emissions limit that will apply to reverberatory furnaces not collocated with a blast furnace and to reverberatory furnaces where the exhaust gases are mixed with electric furnaces. There are seven sources of this type in the industry. We received emissions data for two such affected sources. We are soliciting data for the affected sources of this type for which we don't have emissions data. The MACT floor emissions limit for this affected source was calculated based on the average of the two emissions tests plus variability (based on the 99 percent UPL). The 99 percent UPL for exhaust TEQ concentrations from the affected sources is 0.20 nanograms per dry standard cubic meter (ng/dscm) of TEQ corrected to 7 percent oxygen (O

) to account for dilution. The 99 percent UPL calculated for new affected sources is 0.10 ng/dscm corrected to 7 percent O

With regard to blast furnaces, there are nine sources of this type in the industry. We received dioxin and furan emissions data for two affected sources. Using the data from these two sources, we calculated that the 99 percent UPL for exhaust TEQ concentrations from blast furnaces is 170 ng/dscm at 7 percent O

. For new blast furnaces, the 99 percent UPL is 10 ng/dscm at 7 percent O

. We acknowledge the large difference between the performance of the two affected sources for which we

have data but have not identified a technical basis for the difference. We are soliciting information that may explain these differences and other comments on this topic, including comments regarding the calculation of MACT floor limits for these sources. Additionally, we are soliciting data for the seven affected sources of this type for which we don't have emissions test data.

There are five collocated blast and reverberatory furnaces in the industry. We received emissions test data for one of the affected sources. The calculated 99 percent UPL is 0.5 ng/dscm at 7 percent O

and would apply to both new and existing collocated blast and reverberatory furnaces. We are soliciting data for the remaining four affected sources for which we don't have emissions data.

As previously noted, there is only one rotary furnace currently in operation and we received emissions data for this source. Similar to THC emissions, we have only two emissions test runs for this unit. For the same reasons explained above for THC, we developed a MACT floor limit of 1.0 ng/dscm of TEQ corrected to 7 percent O

based on the 99 percent UL, as opposed to the UPL. Thus, an emissions limit based on the MACT floor for existing and new rotary furnaces would be 1.0 ng/dscm of TEQ corrected to 7 percent O

We then considered beyond-the-floor options to further reduce emissions of dioxins and furans, especially from blast furnaces since blast furnaces have higher emissions compared to the other furnace types. The options considered, included an option based on setting a MACT limit for existing sources based on the performance of the best performing source (

i.e.

, based upon the test data used to calculate the MACT floor for new sources) such that the MACT limit for existing sources would be the same as the MACT limit for new sources (

i.e.

, 10 ng/dscm). However, since we are uncertain about the performance of the other blast furnaces and whether it would be feasible for them to meet a limit of 10 ng/dscm and what the costs would be, we are not proposing MACT limits for existing blast furnaces based on this one set of data in today's action. We do have data for two other blast furnaces that are not controlled with reverberatory furnaces, but because of the configuration of the stacks (blast furnace off-gas is mixed with reverberatory furnace off-gas), we were unable to determine the amount of dioxin that originated from the blast furnace alone compared to the dioxin that was due to the reverberatory furnace. Therefore, these data were not used in the calculation of the blast furnace MACT limits. However, we note that the dioxin concentrations emitted from these sources was in the range of the better performing of the two blast furnaces that were used in the calculations of the MACT Floor. Nevertheless, we are seeking comments as to whether it would be appropriate to establish a MACT limit based upon the data from the one better performing blast furnace or if it would be appropriate to use the data from the mixed sources to determine a MACT limit for Blast furnaces. A MACT limit based upon the data from the one better performing blast furnace (using the 3 test results and applying the 99 percent UPL) would be 10 ng/dscm. We are seeking comments on whether this limit, or some other limit, would be appropriate for Blast Furnaces.

The key conditions typically associated with determining the extent of dioxin and furan formation are combustion efficiency, complex organic fuels, particulate concentration in the flue gas, time in a critical temperature window of approximately 250 to 450 degrees C, and the amount of chlorine present. Increased chlorine concentrations in the furnace feed can increase the dioxin formation. The blast furnaces tested have higher emissions of dioxins and furans than other furnace types. We believe this is because these furnaces are designed to operate at lower temperatures, and these operating temperatures can lead to dioxin formation. Controls for dioxins and furans once they have formed include a high temperature oxidation with quick quenching of the off-gases, or activated carbon injection followed by fabric filtration. Fabric filtration alone has also been demonstrated to provide significant control of dioxins and furans, and because improvements are expected in the performance of fabric filters as a result of standards being proposed for lead in today's action, it is anticipated that some additional reduction in dioxin emissions may occur as a co-benefit of the proposed lower limits for lead. Nevertheless, we are seeking data and information on dioxin emissions from blast furnaces, possible control options, factors that affect dioxin formation and other related information to inform the development of appropriate standards for dioxin and furan emissions from these sources.

As described below, we are also proposing a work practice standard to prevent plastics (which are complex organics and may contain chlorine) from entering furnaces as a beyond-the-floor option. We also considered an option that involves installation of additional afterburner capacity at the facilities operating blast furnaces. This option would include operating the currently installed afterburners at high temperatures and with sufficient residence time to destroy dioxins, or installation of new or additional afterburner capacity with this capability. Based on the current level of performance identified in the ICR surveys, we believe that this option would require four facilities to install afterburner capacity at their facility in order to operate the units at these conditions. The estimated total capital cost for the additional controls is $5.9 million, with a total annualized cost of $2.9 million. We estimate that TEQ emissions would be reduced by roughly 28 grams per year (and organic HAP emissions by 200 tons per year) resulting in a total estimated cost effectiveness of $103,600 per gram of dioxin TEQ and $14,500 per ton organic HAP (see:

Draft MACT Floor Analysis for the Secondary Lead Smelting Source Category

for more details).

In light of the costs of these additional controls and since these controls would have some disadvantages, including causing increases in CO

and NO

(oxides of nitrogen) emissions and increased fuel use, and given the uncertainties regarding how effective these controls would be, we are not proposing more stringent numerical emissions limits based on this beyond-the-floor analysis. Nevertheless, we are seeking data and information on dioxin and furan emissions from blast furnaces and the costs and feasibility of additional controls and emissions reductions, including the beyond-the-floor options described above.

Based on all the analyses described above, under CAA section 112(d)(3), we are proposing to revise the 1997 NESHAP for this source category to include the following emissions limits for dioxins and furans:

• For reverberatory furnaces not collocated with blast furnaces and reverberatory furnaces where the exhaust gases are mixed with electric furnaces, we are proposing emissions limits of 0.20 ng/dscm at 7 percent O

and 0.1 ng/dscm at 7 percent O

for existing and new affected sources, respectively.

• For blast furnaces, we are proposing emissions limits of 170 ng/dscm at 7 percent O

and 10 ng/dscm at 7 percent O

for existing and new sources, respectively.

• For collocated blast and reverberatory furnaces, we are proposing an emissions limit of 0.5 ng/dscm at 7 percent O

for both new and existing sources.

• For rotary furnaces, we are proposing an emissions limit of 1.0 ng/dscm at 7 percent O

for both new and existing sources.

Compliance with the TEQ limits will be demonstrated through an initial

compliance test followed by a compliance test at least once every 5 years. The TEQ emissions will be calculated using the toxic equivalency factors (TEF) outlined by the World Health Organization (WHO) in 2005 (available at Web site:

http://www.epa.gov/raf/hhtefguidance/

). Additionally, we are proposing that facilities must establish limits for the furnace exhaust temperature or afterburner operating temperature during the initial performance test. These temperatures must be maintained and monitored continuously between compliance tests to ensure that the controls are working properly to limit dioxin and furan emissions.

In addition to the emissions limits described above, we are proposing that each facility must operate a process to separate plastic battery casing material prior to introducing feed into a blast furnace. Separation of plastic materials prior to the furnace will limit the organic component in the feed material, minimizing the formation of organic HAP, including dioxins and furans. It is our understanding that all facilities currently have a plastics separation process (that they implement on a voluntary basis) so this proposed requirement results in very minimal additional costs to the industry, if any. We are proposing this as a requirement (

i.e.

, propose to convert this from a voluntary activity to a regulatory requirement) to ensure that facilities continue to implement the separation process to help minimize formation of dioxins and furans. Moreover, we considered proposing a minimum percent of plastics separation requirement (such as ensuring that a minimum of 95 percent of total plastics are separated from the scrap materials before being fed to furnaces). However, we did not have sufficient data to determine an appropriate specific percent. Nevertheless, we are seeking data and comments regarding the percent separation that can be achieved by the available processes and the potential to establish such a minimum percent separation requirement. Moreover, we are seeking information and comments on the various types of plastics separation processes and equipment used, and the relative feasibility and effectiveness of those processes and equipment. We are also seeking comments and information on potential methods to improve overall plastics separation, or methods to improve separation of certain types of plastics that may have higher potential for dioxin formation (

e.g.

, chlorinated plastics). Finally, we are seeking information on appropriate recordkeeping and reporting requirements for these proposed work practices.

3. Mercury Emissions

Based on the emissions test data received under the ICR, we considered proposing an emissions limit for mercury under CAA section 112(d)(3). However, after careful review of the data from the ICR, we have decided not to propose a numerical limit for mercury. We found that the measured stack concentrations of mercury were consistently below the detection levels of the EPA test methods (52 out of 76 total test runs for mercury contained data below the detection limit, or 68 percent of the entire data set). Consequently, EPA considers it impracticable to reliably measure mercury emissions from these units.

We instead considered work practice standards under 112(h) for mercury emissions from this category. The difficulties with accurate measurements at the levels encountered from secondary lead smelters makes a measured standard technologically impracticable, and possibly economically impracticable as well (there appears to be no reliable way to measure compliance at such low levels even with the most carefully conducted tests). Given the factors described above, we conclude it is appropriate to consider work practice standards under 112(h) for mercury rather than numerical emissions limits under Section 112(d)(3).

Therefore, we considered establishing work practice standards under CAA section 112(h) to minimize the potential for mercury emissions. Based on information submitted under the ICR, all facilities have baghouses to control lead and other particulate matter (PM) emissions. These control devices are very effective at controlling non-volatile HAP metals (

e.g.

, a well performing baghouse captures more than 99 percent of lead emissions). These devices do not capture mercury as efficiently as the non-volatile metals. However, available data from other industries (such as coal-fired power plants) indicate that baghouses do provide some level of mercury control. For example, emissions data from coal-fired power plants suggest that baghouses can capture approximately 50 to 90 percent of mercury emissions depending on the speciation of the mercury compounds and other factors. (Reference: “Control of Mercury Emissions from Coal Fired Electric Utility Boilers: An Update.” National Risk Management Research Laboratory, Office of Research and Development, U.S. EPA. February 18, 2005, available at:

http://www.epa.gov/ttn/atw/utility/utiltoxpg.html

Therefore, we are proposing that facilities must have continuous operation of a BLDS with a detection level of 1.0 mg/dscm for PM to ensure their baghouses are working properly as a work practice to limit mercury emissions. This is the same requirement proposed for lead emissions monitoring in this rulemaking under CAA sections 112(f)(2) and 112(d)(6), and will therefore pose no additional burden to the industry. Further, the proposed stack standards for lead will also adequately control mercury such that no further standard is necessary. The standard would be implemented continuously for all metals by the BLDS measurement.

Nevertheless, we also investigated the feasibility of additional work practices to determine if there were other cost-effective pollution prevention measures that could be applied to this industry to further minimize mercury emissions such as source separation approaches. Based on available information, analyses, and discussion with industry, we understand that the vast majority of input materials have very low mercury content (

e.g.

, lead acid batteries). However, we also understand that other types of scrap such as industrial batteries, various construction materials, and other scrap materials are occasionally processed in these furnaces materials. To ensure that mercury-bearing materials are not included in such scrap, we considered proposing that facilities inspect their input scrap materials daily to ensure that mercury-bearing materials are not fed to the furnaces. However, we are not aware of any identifiable or recoverable sources of mercury in the scrap fed to secondary lead smelters and we are also concerned that such work practices could be infeasible. Therefore, we are not proposing such a standard in today's action. However, we are soliciting comments on the appropriateness and feasibility of implementing such a work practice standard for mercury. We are also interested in information regarding any other pollution prevention practices for mercury that may be feasible or appropriate for this source category.

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

As described above, for the Secondary Lead Smelting source category, we conducted an inhalation risk assessment for all HAP emitted. We also conducted multipathway analyses for cadmium, dioxins and furans, mercury, and POM, as well as air-related multipathway

analyses for lead. With respect to lead, we used the recently promulgated lead NAAQS to evaluate the potential for air-related multipathway and environmental effects. Furthermore, we conducted a demographic analysis of population risks. Details of the risk assessments and additional analyses can be found in the residual risk documentation referenced in Section III.B of this preamble, which is available in the docket for this action. The Agency considered the available health information—the MIR; the numbers of persons in various risk ranges; cancer incidence; the maximum non-cancer hazard index (HI); the maximum acute non-cancer hazard; the extent of non-cancer risks; the potential for adverse environmental effects; and distribution of risks in the exposed population (54 FR 38044, September 14, 1989)—in developing the proposed CAA section 112(f)(2) standards for the Secondary Lead source category.

1. Inhalation Risk Assessment Results

Table 3 of this preamble provides an overall summary of the results of the inhalation risk assessment.

Table 3—Secondary Lead Smelting Inhalation Risk Assessment Results

Maximum individual cancer risk

(in 1 million)

Based on actual emissions level

Based on allowable emissions level

Estimated population at increased risk of

cancer ≥1-in-1 million

Estimated annual

cancer

incidence

(cases per year)

Maximum chronic

non-cancer TOSHI

Based on actual

emissions

level

Based on allowable emissions level

Maximum screening acute

non-cancer HQ

200

128,000

0.02

0.6

Estimated maximum individual excess lifetime cancer risk due to HAP emissions from the source category.

Maximum TOSHI. The target organ with the highest TOSHI for the Secondary Lead Smelting source category is the kidney.

The maximum HQ acute value of 30, driven by emissions of arsenic, is based on the only available acute dose-response value available for arsenic, which is the REL. See Section III.B of this preamble for explanation of acute dose-response values.

The results of the chronic inhalation cancer risk assessment indicate that, based on estimates of current actual emissions, the maximum individual lifetime cancer risk (MIR) could be up to 50-in-1 million, with fugitive dust emissions of arsenic, and to a lesser extent fugitive dust emissions of cadmium (see below), driving these risks. The total estimated cancer incidence from this source category based on actual emission levels is 0.02 excess cancer cases per year or one case in every 50 years, with emissions of arsenic and cadmium contributing 73 percent and 15 percent respectively, to this cancer incidence. In addition, we note that approximately 1,500 people are estimated to have cancer risks greater than 10-in-1 million, and approximately 128,000 people are estimated to have risks greater than 1-in-1 million. When considering the risks associated with MACT-allowable emissions, the MIR could be up to 200-in-1 million.

The maximum modeled chronic non-cancer TOSHI value is 0.6 based on actual emissions, driven primarily by fugitive dust emissions of arsenic. When considering MACT allowable emissions, the maximum chronic non-cancer TOSHI value could be up to 3.

Based on using the acute REL to assess possible acute non-cancer effects due to emissions of arsenic, our screening analysis estimates that the maximum acute HQ value for a facility in this source category could be up to 30. Moreover, this analysis estimates that acute HQ values could exceed a value of 1 at nine facilities.

These exceedances are mainly due to fugitive emissions at most of these nine facilities. However, stack emissions, while generally not the principle driver of maximum acute HQ values greater than 1, contribute about 90 percent of the risk at the facility which has the maximum acute HQ screening value of 30. We note that the California REL is the only acute value available, and we request comments on the use of this value as well as comments on the existence of other peer reviewed values that may be used to inform acute risks.

Individual facility acute HQ values for all facilities can be found in Appendix 5, Table 3, of the risk assessment document that is included in the docket for this proposed rulemaking. Acute HQ values exceeding a value of 1 were as follows: 2, 2, 2, 3, 4, 5, 6, 20 and 30.

In summary, the analysis indicates that arsenic and cadmium emissions pose risks to public health due to inhalation exposures resulting from both fugitive and stack emissions (see above). Lead and dioxin and furan emissions also pose risks to public health, but these HAP are assessed separately as part of multipathway assessments described below. Based on our risk assessment, no other HAP were identified as contributing significant risks.

With respect to the potential for adverse environmental effects from non PB-HAP, we note that that there is a lack of information about specific adverse environmental effects occurring at a given concentration of HAP for this source category. However, given that all chronic non-cancer HQ values considering actual emissions are less than 1 using human health reference values, we believe that it is unlikely that adverse environmental effects would occur at the actual HAP concentrations estimated in our human health risk assessment.

2. Multipathway Risk Assessments and Results

As noted above, in evaluating the potential for multipathway effects from emissions of lead, we compared modeled maximum 3-month rolling average lead concentrations (based on estimates of actual emissions) with the lead NAAQS. Results of this analysis indicate that, if current emission levels continue, the lead NAAQS could be exceeded at 12 of the 14 facilities and that nine facilities could have ambient levels that are at least 2-3 times above the NAAQS, largely due to actual fugitive dust emissions. Moreover, available ambient monitoring data for lead confirms that ambient air concentrations of lead are well above the lead NAAQS near seven of these facilities. As described in the technical document

Draft Summary of Ambient Lead Monitoring Data near Secondary Lead Smelting Facilities,

which is available the docket, the measured ambient levels (for 3-month maximum rolling concentrations) for year 2010 range from 1.00 to 0.26 μg/m

for the seven facilities, and for year 2008, the measured values were up to 2.49 μg/m

When considering actual stack emissions only (

i.e.

, in the theoretical absence of fugitive dust emissions), we estimate that one facility would be about 3 times above the NAAQS. Moreover, we estimate that the risks

associated with MACT-allowable stack emissions would be significantly higher. For example, we estimate that based on MACT-allowable emissions from stacks alone (not including fugitive dust emissions), the ambient lead concentrations could be about 10 times above the NAAQS at two facilities.

Considering the results presented above, fugitive dust emissions, and to a lesser extent emissions from stacks, resulted in modeled lead concentrations above the NAAQS. We also note when considering all emissions (

i.e.,

stack and fugitive dust emissions), our analysis indicates that maximum off-site 3-month rolling average lead concentrations could be up to 20 times the lead NAAQS near one facility's fenceline.

Secondary lead smelting modeled ambient lead concentrations for all facilities can be found in Table 3.2-3 of the risk assessment document that is included in the docket for this proposed rulemaking. Facilities with modeled ambient lead concentrations exceeding the NAAQS did so by 23, 19, 10, 6, 5, 4, 4, 3, 3, 1.5, 1.4 and 1.3 fold.

To evaluate the potential for adverse environmental effects from lead, we compared modeled maximum 3-month rolling average lead ambient air concentrations with the current secondary lead NAAQS, which is identical to the primary, public health-based standard (see Section III.B.3 of this preamble). Thus, our analyses discussed above also indicate the potential for adverse environmental effects from emissions of lead.

As noted above (section III.B.4), based on a multipathway screening analysis for emissions of non-lead PB-HAP from this source category, emissions of cadmium, dioxins and furans, and POM were all above the

de minimis

emissions rates that suggest the potential for non-negligible (

i.e.,

greater than 1-in-1 million cancer risk or greater than a noncancer hazard quotient of 1) risk of adverse health effects from multipathway exposures.

With regard to mercury, emissions are quite low for this category. In fact, most emissions tests for mercury for this source category were below MDL. Nevertheless, using conservative worst-case assumptions (

e.g.,

assuming all non-detects for mercury were equal to the detection limit, as described in Sections IV.A and IV.B of this preamble), we estimated that mercury emissions could be above the

de minimis

emissions rates described above (see Section III.B of this preamble).

For facilities in this source category: Cadmium, BaP, dioxins and furans, and mercury estimated emission rates were up to about 8, 24, 23,000, and 4 times above their respective

de minimis

emissions rates.

As a result of this conservative screening analysis, we performed two detailed case study multipathway analyses for these four PB-HAP in areas near the Frisco Recycling (Frisco, TX) and Revere Smelting & Refining (Middletown, NY) facilities.

Moreover, as previously mentioned above (section III.B.4), in order to more fully characterize the potential multipathway risks associated with high end consumption of PB-HAP contaminated food, we present results based on RME and CTE scenarios. The RME scenario utilizes 90th percentile ingestion rates for farmers, recreational anglers, and for three subpopulations of recreational anglers) who have higher rates of fish consumption (Hispanic, Laotian, and Vietnamese descent), while the CTE scenario utilizes mean ingestion rates for each of these groups. We provide results from both scenarios to illustrate the range of potential modeled exposures and risks that may exist in the high-end of the complete distribution of potential multipathway risks for this source category.

24 As previously noted above, the reasons that EPA selected these two facilities for analysis are described in detail in section 2.5.1 of the document Human Health Multipathway Residual Risk Assessment for the Secondary Lead Smelting Source Category, which can be found in the docket for the proposed rule. The selection criteria for modeling these two facilities included emissions rates of PB-HAPs, proximity to water bodies, proximity to farmland, average rainfall, average wind speed and direction, smelting furnace type, local change in elevation, and geographic representativeness of sites throughout the U.S.

Considering the RME scenario, results of this analysis estimate the MIR for dioxin to be 30 in a million (based on Laotian

This text is long and has been trimmed here. Open the source document for the complete record.

This is a copy of a public record, reproduced as it was published. It is not legal advice, and it may not be the version a court would rely on. Check the official source before you cite it.