# National Emission Standards for Hazardous Air Pollutants: Boat Manufacturing and Reinforced Plastic Composites Production Residual Risk and Technology Review > Briefs, arguments, decisions, and more. URL: https://www.frixlaw.com/law-library/documents/fr%3A2019-09583 ## Record - **Collection:** Federal Register - **Document type:** Proposed Rule - **Published:** May 17, 2019 - **Citation:** 84 FR 22642 ## Text ENVIRONMENTAL PROTECTION AGENCY 40 CFR Part 63 [EPA-HQ-OAR-2016-0447 and EPA-HQ-OAR-2016-0449; FRL-9992-76-OAR] RIN 2060-AT12 National Emission Standards for Hazardous Air Pollutants: Boat Manufacturing and Reinforced Plastic Composites Production Residual Risk and Technology Review AGENCY: Environmental Protection Agency (EPA). ACTION: Proposed rule. SUMMARY: The Environmental Protection Agency (EPA) is proposing amendments to the National Emission Standards for Hazardous Air Pollutants (NESHAP) for Boat Manufacturing and the NESHAP for Reinforced Plastic Composites Production. The proposed amendments address the results of the residual risk and technology review (RTR) conducted as required under the Clean Air Act (CAA) for these source categories. The EPA is proposing to find the risks due to emissions of air toxics from these source categories under the current standards to be acceptable and that the standards provide an ample margin of safety to protect public health. We are proposing no revisions to the numerical emission limits or other aspects of the rules based on these risk analyses or technology reviews. Additionally, the EPA is proposing to amend provisions addressing emissions during periods of startup, shutdown, and malfunction (SSM) and to amend provisions regarding electronic reporting of certain notifications, performance test results, and semiannual reports. DATES: Comments. Comments must be received on or before July 1, 2019. Under the Paperwork Reduction Act (PRA), comments on the information collection provisions are best assured of consideration if the Office of Management and Budget (OMB) receives a copy of your comments on or before June 17, 2019. Public Hearing. If anyone contacts us requesting a public hearing on or before May 22, 2019, we will hold a hearing. Additional information about the hearing, if requested, will be published in a subsequent Federal Register document and posted at https://www.epa.gov/stationary-sources-air-pollution/boat-manufacturing-national-emission-standards-hazardous-air for the Boat Manufacturing NESHAP, and https://www.epa.gov/stationary-sources-air-pollution/reinforced-plastic-composites-production-national-emission for the Reinforced Plastic Composites Production NESHAP. See SUPPLEMENTARY INFORMATION for information on requesting and registering for a public hearing. ADDRESSES: Comments. Submit your comments, identified by Docket ID No. EPA-HQ-OAR-2016-0447 for the Boat Manufacturing NESHAP and Docket ID No. EPA-HQ-OAR-2016-0449 for the Reinforced Plastic Composites Production NESHAP, at https://www.regulations.gov. Follow the online instructions for submitting comments. Once submitted, comments cannot be edited or removed from Regulations.gov . See SUPPLEMENTARY INFORMATION for detail about how the EPA treats submitted comments. Regulations.gov is our preferred method of receiving comments. However, the following other submission methods are also accepted: • Email: a-and-r-docket@epa.gov. Include Docket ID No. EPA-HQ-OAR-2016-0447 for the Boat Manufacturing NESHAP or Docket ID No. EPA-HQ-OAR-2016-0449 for the Reinforced Plastic Composites Production NESHAP in the subject line of the message. • Fax: (202) 566-9744. Attention Docket ID No. EPA-HQ-OAR-2016-0447 for the Boat Manufacturing NESHAP or Docket ID No. EPA-HQ-OAR-2016-0449 for the Reinforced Plastic Composites Production NESHAP. • Mail: To ship or send mail via the United States Postal Service, use the following address: U.S. Environmental Protection Agency, EPA Docket Center, Docket ID No. EPA-HQ-OAR-2016-0447 for the Boat Manufacturing NESHAP or Docket ID No. EPA-HQ-OAR-2016-0449 for the Reinforced Plastic Composites Production NESHAP, Mail Code 28221T, 1200 Pennsylvania Avenue NW, Washington, DC 20460. • Hand/Courier Delivery: Use the following Docket Center address if you are using express mail, commercial delivery, hand delivery, or courier: EPA Docket Center, EPA WJC West Building, Room 3334, 1301 Constitution Avenue NW, Washington, DC 20004. Delivery verification signatures will be available only during regular business hours. FOR FURTHER INFORMATION CONTACT: For questions about this proposed action, contact Mr. Brian Storey, Sector Policies and Programs Division (D243-04), Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711; telephone number: (919) 541-1103; fax number: (919) 541-4991; and email address: storey.brian@epa.gov. For specific information regarding the risk modeling methodology, contact Mr. James Hirtz, Health and Environmental Impacts Division (C539-02), Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711; telephone number: (919) 541-0881; fax number: (919) 541-0840; and email address: hirtz.james@epa.gov. For information about the applicability of the Boat Manufacturing NESHAP or Reinforced Plastic Composites Production NESHAP to a particular entity, contact Mr. John Cox, Office of Enforcement and Compliance Assurance, U.S. Environmental Protection Agency, EPA WJC South Building (Mail Code 2221A), 1200 Pennsylvania Avenue NW, Washington DC 20460; telephone number: (202) 564-1395; and email address: cox.john@epa.gov. SUPPLEMENTARY INFORMATION: Public hearing. Please contact Ms. Nancy Perry at (919) 541-5628 or by email at perry.nancy@epa.gov to request a public hearing, to register to speak at the public hearing, or to inquire as to whether a public hearing will be held. Docket. The EPA has established a docket for this rulemaking under Docket ID No. EPA-HQ-OAR-2016-0447 for the Boat Manufacturing NESHAP or Docket ID No. EPA-HQ-OAR-2016-0449 for the Reinforced Plastic Composites Production NESHAP. All documents in the docket are listed in Regulations.gov . Although listed, some information is not publicly available, e.g., Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Certain other material, such as copyrighted material, is not placed on the internet and will be publicly available only in hard copy. Publicly available docket materials are available either electronically in Regulations.gov or in hard copy at the EPA Docket Center, Room 3334, EPA WJC West Building, 1301 Constitution Avenue NW, Washington, DC. The Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal holidays. The telephone number for the Public Reading Room is (202) 566-1744, and the telephone number for the EPA Docket Center is (202) 566-1742. Instructions. Direct your comments to Docket ID No. EPA-HQ-OAR-2016-0447 for the Boat Manufacturing NESHAP or Docket ID No. EPA-HQ- OAR-2016-0449 for the Reinforced Plastic Composites Production NESHAP. The EPA's policy is that all comments received will be included in the public docket without change and may be made available online at https://www.regulations.gov, including any personal information provided, unless the comment includes information claimed to be CBI or other information whose disclosure is restricted by statute. Do not submit information that you consider to be CBI or otherwise protected through https://www.regulations.gov or email. This type of information should be submitted by mail as discussed below. The EPA may publish any comment received to its public docket. Multimedia submissions (audio, video, etc.) must be accompanied by a written comment. The written comment is considered the official comment and should include discussion of all points you wish to make. The EPA will generally not consider comments or comment contents located outside of the primary submission ( i.e., on the Web, cloud, or other file sharing system). For additional submission methods, the full EPA public comment policy, information about CBI or multimedia submissions, and general guidance on making effective comments, please visit https://www2.epa.gov/dockets/commenting-epa-dockets. The https://www.regulations.gov website allows you to submit your comment anonymously, which means the EPA will not know your identity or contact information unless you provide it in the body of your comment. If you send an email comment directly to the EPA without going through https://www.regulations.gov, your email address will be automatically captured and included as part of the comment that is placed in the public docket and made available on the internet. If you submit an electronic comment, the EPA recommends that you include your name and other contact information in the body of your comment and with any digital storage media you submit. If the EPA cannot read your comment due to technical difficulties and cannot contact you for clarification, the EPA may not be able to consider your comment. Electronic files should not include special characters or any form of encryption and be free of any defects or viruses. For additional information about the EPA's public docket, visit the EPA Docket Center homepage at https://www.epa.gov/dockets. Submitting CBI. Do not submit information containing CBI to the EPA through https://www.regulations.gov or email. Clearly mark the part or all of the information that you claim to be CBI. For CBI information on any digital storage media that you mail to the EPA, mark the outside of the digital storage media as CBI and then identify electronically within the digital storage media the specific information that is claimed as CBI. In addition to one complete version of the comments that includes information claimed as CBI, you must submit a copy of the comments that does not contain the information claimed as CBI directly to the public docket through the procedures outlined in Instructions above. If you submit any digital storage media that does not contain CBI, mark the outside of the digital storage media clearly that it does not contain CBI. Information not marked as CBI will be included in the public docket and the EPA's electronic public docket without prior notice. Information marked as CBI will not be disclosed except in accordance with procedures set forth in 40 Code of Federal Regulations (CFR) part 2. Send or deliver information identified as CBI only to the following address: OAQPS Document Control Officer (C404-02), OAQPS, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, Attention Docket ID No. EPA-HQ-OAR-2016-0447 for the Boat Manufacturing NESHAP or Docket ID No. EPA-HQ-OAR-2016-0449 for the Reinforced Plastic Composites Production NESHAP. Preamble Acronyms and Abbreviations. We use multiple acronyms and terms in this preamble. While this list may not be exhaustive, to ease the reading of this preamble and for reference purposes, the EPA defines the following terms and acronyms here: AEGL acute exposure guideline level AERMOD air dispersion model used by the HEM-3 model ATSDR Agency for Toxic Substances and Disease Registry BMC bulk molding compound CAA Clean Air Act CalEPA California EPA CBI Confidential Business Information CEDRI compliance and emissions data reporting interface CFR Code of Federal Regulations EPA Environmental Protection Agency ERPG Emergency Response Planning Guideline ERT electronic reporting tool GACT generally available control technologies HAP hazardous air pollutant(s) HCl hydrochloric acid HEM-3 Human Exposure Model, Version 1.1.0 HF hydrogen fluoride HI hazard index HQ hazard quotient ICR information collection request IRIS Integrated Risk Information System km kilometer MACT maximum achievable control technology MDI 4,4′-diphenylmethane diisocyanate mg/m 3 milligrams per cubic meter MIR maximum individual risk MMA methyl methacrylate NAAQS National Ambient Air Quality Standards NAICS North American Industry Classification System NEI national emissions inventory NESHAP national emission standards for hazardous air pollutants NSR new source review NTTAA National Technology Transfer and Advancement Act OAQPS Office of Air Quality Planning and Standards OMB Office of Management and Budget PB-HAP hazardous air pollutants known to be persistent and bio-accumulative in the environment POM polycyclic organic matter ppm parts per million PRA Paperwork Reduction Act RBLC Reasonably Available Control Technology, Best Available Control Technology, and Lowest Achievable Emission Rate (RACT/BACT/LAER) Clearinghouse REL reference exposure level RFA Regulatory Flexibility Act RfC reference concentration RTR residual risk and technology review SAB Science Advisory Board SMC sheet molding compound SSM startup, shutdown, and malfunction TOSHI target organ-specific hazard index tpy tons per year TRIM.FaTE Total Risk Integrated Methodology. Fate, Transport, and Ecological Exposure model UF uncertainty factor µg/m 3 microgram per cubic meter UMRA Unfunded Mandates Reform Act URE unit risk estimate Organization of this Document. The information in this preamble is organized as follows: I. General Information A. Does this action apply to me? B. Where can I get a copy of this document and other related information? II. Background A. What is the statutory authority for this action? B. What is this source category and how does the current NESHAP regulate its HAP emissions? C. What data collection activities were conducted to support this action? D. What other relevant background information and data are available? III. Analytical Procedures and Decision Making A. How do we consider risk in our decision-making? B. How do we perform the technology review? C. How do we estimate post-MACT risk posed by the source category? IV. Analytical Results and Proposed Decisions A. What are the results of the risk assessment and analyses for the Boat Manufacturing source category? B. What are our proposed decisions regarding risk acceptability, ample margin of safety, and adverse environmental effect for the Boat Manufacturing source category? C. What are the results and proposed decisions based on our technology review for the Boat Manufacturing source category? D. What other actions are we proposing for the Boat Manufacturing source category? E. What compliance dates are we proposing for the Boat Manufacturing source category? F. What are the results of the risk assessment and analyses for the Reinforced Plastic Composites Production source category? G. What are our proposed decisions regarding risk acceptability, ample margin of safety, and adverse environmental effect for the Reinforced Plastic Composites Production source category? H. What are the results and proposed decisions based on our technology review for the Reinforced Plastic Composites Production source category? I. What other actions are we proposing for the Reinforced Plastic Composites Production source category? J. What compliance dates are we proposing for the Reinforced Plastic Composites Production source category? V. Summary of Cost, Environmental, and Economic Impacts A. What are the affected sources? B. What are the air quality impacts? C. What are the cost impacts? D. What are the economic impacts? E. What are the benefits? VI. Request for Comments VII. Submitting Data Corrections VIII. Statutory and Executive Order Reviews A. Executive Order 12866: Regulatory Planning and Review and Executive Order 13563: Improving Regulation and Regulatory Review B. Executive Order 13771: Reducing Regulation and Controlling Regulatory Costs C. Paperwork Reduction Act (PRA) D. Regulatory Flexibility Act (RFA) E. Unfunded Mandates Reform Act (UMRA) F. Executive Order 13132: Federalism G. Executive Order 13175: Consultation and Coordination With Indian Tribal Governments H. Executive Order 13045: Protection of Children From Environmental Health Risks and Safety Risks I. Executive Order 13211: Actions Concerning Regulations That Significantly Affect Energy Supply, Distribution, or Use J. National Technology Transfer and Advancement Act (NTTAA) K. Executive Order 12898: Federal Actions to Address Environmental Justice in Minority Populations and Low-Income Populations I. General Information A. Does this action apply to me? Table 1 of this preamble lists the NESHAP and associated regulated industrial source categories that are the subject of this proposal. Table 1 is not intended to be exhaustive, but rather provides a guide for readers regarding the entities that this proposed action is likely to affect. The proposed standards, once promulgated, will be directly applicable to the affected sources. Federal, state, local, and tribal government entities would not be affected by this proposed action. Table 1—NESHAP and Industrial Source Categories Affected by This Proposed Action NESHAP and source category NAICS code 1 Regulated entities Boat Manufacturing 336612 Boat manufacturing facilities that perform fiberglass production operations or aluminum coating operations. Reinforced Plastic Composites Production 326113, 326121, 326122, 326130, 326140, 326191, 327110, 327991, 332321, 332420, 333132, 333415, 333611, 333924, 334310, 335311, 335313, 335932, 336111, 336211, 336213, 336214, 336320, 336413, 336510, 337110, 337125, 337127, 337215, 339920, 339991 Reinforced plastic composites production facilities that manufacture intermediate, and/or final products using styrene containing thermoset resins and gel coats. 1 North American Industry Classification System. B. Where can I get a copy of this document and other related information? In addition to being available in the docket, an electronic copy of this action is available on the internet. Following signature by the EPA Administrator, the EPA will post a copy of this proposed action at https://www.epa.gov/stationary-sources-air-pollution/boat-manufacturing-national-emission-standards-hazardous-air for the Boat Manufacturing NESHAP, and https://www.epa.gov/stationary-sources-air-pollution/reinforced-plastic-composites-production-national-emission for the Reinforced Plastic Composites Production NESHAP. Following publication in the Federal Register , the EPA will post the Federal Register version of the proposal and key technical documents at this same website. Information on the overall RTR program is available at https://www3.epa.gov/ttn/atw/rrisk/rtrpg.html. A redline version of the regulatory language that incorporates the proposed changes in this action is available in the docket for this action (Docket ID No. EPA-HQ-OAR-2016-0447 for the Boat Manufacturing NESHAP or Docket ID No. EPA-HQ-OAR-2016-0449 for the Reinforced Plastic Composites Production NESHAP). II. Background A. What is the statutory authority for this action? The statutory authority for this action is provided by sections 112 and 301 of the CAA, as amended (42 U.S.C. 7401 et seq. ). Section 112 of the CAA establishes a two-stage regulatory process to develop standards for emissions of hazardous air pollutants (HAP) from stationary sources. Generally, the first stage involves establishing technology-based standards and the second stage involves evaluating those standards that are based on maximum achievable control technology (MACT) to determine whether additional standards are needed to address any remaining risk associated with HAP emissions. This second stage is commonly referred to as the “residual risk review.” In addition to the residual risk review, the CAA also requires the EPA to review standards set under CAA section 112 every 8 years to determine if there are “developments in practices, processes, or control technologies” that may be appropriate to incorporate into the standards. This review is commonly referred to as the “technology review.” When the two reviews are combined into a single rulemaking, it is commonly referred to as the “risk and technology review.” The discussion that follows identifies the most relevant statutory sections and briefly explains the contours of the methodology used to implement these statutory requirements. A more comprehensive discussion appears in the document titled CAA Section 112 Risk and Technology Reviews: Statutory Authority and Methodology in the docket for this rulemaking. In the first stage of the CAA section 112 standard setting process, the EPA promulgates technology-based standards under CAA section 112(d) for categories of sources identified as emitting one or more of the HAP listed in CAA section 112(b). Sources of HAP emissions are either major sources or area sources, and CAA section 112 establishes different requirements for major source standards and area source standards. “Major sources” are those that emit or have the potential to emit 10 tons per year (tpy) or more of a single HAP or 25 tpy or more of any combination of HAP. All other sources are “area sources.” For major sources, CAA section 112(d)(2) provides that the technology-based NESHAP must reflect the maximum degree of emission reductions of HAP achievable (after considering cost, energy requirements, and non-air quality health and environmental impacts). These standards are commonly referred to as MACT standards. CAA section 112(d)(3) also establishes a minimum control level for MACT standards, known as the MACT “floor.” The EPA must also consider control options that are more stringent than the floor. Standards more stringent than the floor are commonly referred to as beyond-the-floor standards. In certain instances, as provided in CAA section 112(h), the EPA may set work practice standards where it is not feasible to prescribe or enforce a numerical emission standard. For area sources, CAA section 112(d)(5) gives the EPA discretion to set standards based on generally available control technologies or management practices (GACT standards) in lieu of MACT standards. The second stage in standard-setting focuses on identifying and addressing any remaining ( i.e., “residual”) risk according to CAA section 112(f). For source categories subject to MACT standards, section 112(f)(2) of the CAA requires the EPA to determine whether promulgation of additional standards is needed to provide an ample margin of safety to protect public health or to prevent an adverse environmental effect. Section 112(d)(5) of the CAA provides that this residual risk review is not required for categories of area sources subject to GACT standards. Section 112(f)(2)(B) of the CAA further expressly preserves the EPA's use of the two-step approach for developing standards to address any residual risk and the Agency's interpretation of “ample margin of safety” developed in the National Emissions Standards for Hazardous Air Pollutants: Benzene Emissions from Maleic Anhydride Plants, Ethylbenzene/Styrene Plants, Benzene Storage Vessels, Benzene Equipment Leaks, and Coke By-Product Recovery Plants (Benzene NESHAP) (54 FR 38044, September 14, 1989). The EPA notified Congress in the Risk Report that the Agency intended to use the Benzene NESHAP approach in making CAA section 112(f) residual risk determinations (EPA-453/R-99-001, p. ES-11). The EPA subsequently adopted this approach in its residual risk determinations and the United States Court of Appeals for the District of Columbia Circuit (the Court) upheld the EPA's interpretation that CAA section 112(f)(2) incorporates the approach established in the Benzene NESHAP. See NRDC v. EPA, 529 F.3d 1077, 1083 (D.C. Cir. 2008). The approach incorporated into the CAA and used by the EPA to evaluate residual risk and to develop standards under CAA section 112(f)(2) is a two-step approach. In the first step, the EPA determines whether risks are acceptable. This determination “considers all health information, including risk estimation uncertainty, and includes a presumptive limit on maximum individual lifetime [cancer] risk (MIR) 1 of approximately 1 in 10 thousand.” 54 FR 38045, September 14, 1989. If risks are unacceptable, the EPA must determine the emissions standards necessary to reduce risk to an acceptable level without considering costs. In the second step of the approach, the EPA considers whether the emissions standards provide an ample margin of safety to protect public health “in consideration of all health information, including the number of persons at risk levels higher than approximately 1 in 1 million, as well as other relevant factors, including costs and economic impacts, technological feasibility, and other factors relevant to each particular decision.” Id. The EPA must promulgate emission standards necessary to provide an ample margin of safety to protect public health. After conducting the ample margin of safety analysis, we consider whether a more stringent standard is necessary to prevent, taking into consideration costs, energy, safety, and other relevant factors, an adverse environmental effect. 1 Although defined as “maximum individual risk,” MIR refers only to cancer risk. MIR, one metric for assessing cancer risk, is the estimated risk if an individual were exposed to the maximum level of a pollutant for a lifetime. CAA section 112(d)(6) separately requires the EPA to review standards promulgated under CAA section 112 and revise them “as necessary (taking into account developments in practices, processes, and control technologies)” no less often than every 8 years. In conducting this review, which we call the “technology review,” the EPA is not required to recalculate the MACT floor. Natural Resources Defense Council (NRDC) v. EPA, 529 F.3d 1077, 1084 (D.C. Cir. 2008). Association of Battery Recyclers, Inc. v. EPA, 716 F.3d 667 (D.C. Cir. 2013). The EPA may consider cost in deciding whether to revise the standards pursuant to CAA section 112(d)(6). B. What is this source category and how does the current NESHAP regulate its HAP emissions? 1. What is the Boat Manufacturing source category and how does the current NESHAP regulate its HAP emissions? The Boat Manufacturing NESHAP was promulgated on August 22, 2001 (66 FR 44218), and codified at 40 CFR part 63, subpart VVVV. As promulgated, the Boat Manufacturing NESHAP applies to fiberglass and aluminum boat manufacturing operations located at facilities considered to be major sources of HAP emissions. The HAP emissions from these boat manufacturing operations and processes are fugitive emissions. Fugitive emissions result from HAP evaporating from the resins, gel coats, solvents, adhesives, and surface coatings used in manufacturing processes. The following is a brief description of these processes and operations found at boat manufacturing facilities: Fiberglass boat manufacturing operations; fabric and carpet adhesive operations; and aluminum boat surface coating operations. Fiberglass boat manufacturing operations. Fiberglass boat manufacturing involves using glass fiber reinforcements laid in a mold and saturating the fiberglass with resin. The resin hardens to form a rigid plastic part reinforced with fiberglass. Manufacturing processes are generally considered either “open molding” or “closed molding.” In open molding, the outer parts of the boat are built by first spraying a mold with a layer of gel coat, which is a pigmented polyester resin that hardens and becomes the smooth outside surface of the part. The inside of the hardened gel coat layer is coated with chopped glass fibers and polyester or vinylester resin. Additional layers of fiberglass cloth or chopped glass fibers saturated with resin are added until the part is the final thickness. The same basic process is used to build or repair molds with tooling gel coat and tooling resin. Closed molding processes include resin infusion molding and resin transfer molding. These processes are typically used to produce smaller boat parts and involve packing a mold cavity with fiberglass reinforcement and infusing the fiber with resin either under pressure, where the resin is “pushed” into the mold cavity, or under vacuum, where the air of the mold cavity is removed and replaced by resin. In either process, the mold is sealed, to effectively transfer the resin into the mold cavity and to control the saturation of the fiber reinforcement. The resins that are used in fiberglass boat manufacturing contain styrene as a solvent and a cross-linking agent. Gel coats contain styrene and methyl methacrylate (MMA) which provides resistance to degradation of the gel coat by ultraviolet light. Styrene and MMA are HAP, and, in an open mold process, a fraction evaporates during resin and gel coat application and curing. Resins and gel coats containing styrene and MMA are also used to make the molds used in the manufacturing process. Mixing is done to resins or gel coats to mix the resins and gel coats with promoters, fillers, or other additives before being applied to the mold. Some HAP from the resins and gel coats are emitted during the mixing process. Resin and gel coat application equipment requires solvent cleaning to remove uncured resin or gel coat when not in use. The resin or gel coat can catalyze in the hoses or gun if not flushed with a solvent after each use. For some types of boats, the void spaces between the walls of the boat are filled with a foam to provide additional buoyancy to the boat, once constructed. The foam is formed by pouring a two-part foam product into the void space. The two-part product consists of resin, where the HAP is predominantly styrene and 4,4′-diphenylmethane diisocyanate (MDI), another HAP in the process. The MDI component of the foam is a reactant that reacts with the resin, when combined, to form the hardened polyurethane foam. Fabric and carpet adhesive operations. The interiors of many types of fiberglass boats and aluminum boats are covered with carpeting or fabric to improve the appearance, provide traction, or deaden sound. The material is bonded to the interior with contact adhesives. The adhesives can include HAP such as methylene chloride, toluene, xylenes, and methyl chloroform. Aluminum boat surface coatings. Aluminum boat hull topsides and decks are painted with coatings applied with spray guns. These coatings may be high-gloss polyurethane coatings or low-gloss single-part coatings. These surface coatings often contain HAP solvents, such as toluene, xylenes, and isocyanates. The HAP-containing solvents are also used to clean surfaces before finishing (wipe-down solvents) and for cleaning paint and coating spray guns. The Boat Manufacturing NESHAP regulates organic HAP from sources that manufacture non-commercial and non-military aluminum boats or all types of fiberglass boats. Coating operations on vessels used for commercial and military purposes are covered by the Shipbuilding and Repair NESHAP (40 CFR part 63, subpart II). The Boat Manufacturing NESHAP applies to the following operations: All open molding operations, including pigmented gel coat, clear gel coat, production resin, tooling resin, and tooling gel coat, and all closed molding resin operations. The NESHAP regulates HAP emissions by setting a HAP content limit for the resins and gel coats used at each regulated open molding resin and gel coat operation. For each regulated open molding resin operation, the NESHAP establishes separate HAP content limits for atomized and non-atomized resin application methods. For closed molding operations, no limits apply to the resin application operation if it meets the specific definition of closed molding provided in the NESHAP. If a molding operation does not meet the definition of closed molding that is provided in the NESHAP, then it must comply with the applicable emission limits for open molding. Other operations are subject to either work practice requirements or HAP content limits, including the following: • All resin and gel coat application equipment cleaning; • All resin and gel coat mixing operations; and • All carpet and fabric adhesive operations. Resin and gel coat mixing containers with a capacity of 208 liters (55 gallons) or more must be covered with tightly fitted lids. Routine resin and gel coat equipment cleaning operations must use solvents containing no more than 5-percent organic HAP, but solvents used to remove cured resin or gel coat from equipment are exempt from the HAP content limits. However, the containers used to hold the exempt solvent and to clean equipment being used with cured resin and gel coat must be covered, and there is an annual limit on the amount of exempt solvent that can be used. Lastly, the NESHAP includes HAP limits for carpet and fabric adhesives operations, limiting use to those adhesives that contain no more than 5-percent organic HAP by weight. The Boat Manufacturing NESHAP applies to aluminum recreational boat manufacturing facilities performing the following operations: • All aluminum recreational boat surface coating and associated spray gun cleaning and wipe-down solvent operations; and • All carpet and fabric adhesive operations. The NESHAP includes the following requirements for aluminum recreational boat manufacturing: • Aluminum wipe-down solvents are limited to no more than 0.33 kilograms of organic HAP per liter of total coating solids applied (2.75 pounds per gallon) from aluminum primers, clear coats, and top coats combined (no limit applies when cleaning surfaces are receiving decals or adhesive graphics). • Aluminum recreational boat surface coatings (including thinners, activators, primers, topcoats, and clear coats) are limited to no more than 1.22 kilograms of organic HAP per liter of total coating solids applied (10.18 pounds per gallon) from aluminum primers, clear coats, and top coats combined. • Combined aluminum surface coatings and aluminum wipe-down solvents are limited to no more than 1.55 kilograms of organic HAP per liter of total coating solids applied (12.9 pounds per gallon) from aluminum primers, clear coats, and top coats combined. In addition, aluminum recreational boat manufacturing facilities must meet work practice standards to ensure that spray guns are cleaned and the cleaning solvent is stored in an enclosed device, and that the enclosure remains closed when not in use. The applicability of Boat Manufacturing NESHAP requirements is described in greater detail in the 2001 rule (66 FR 44218) and 40 CFR part 63, subpart VVVV. 2. What is the Reinforced Plastic Composites Production source category and how does the current NESHAP regulate its HAP emissions? The Reinforced Plastic Composites Production NESHAP was originally promulgated on April 21, 2003 (68 FR 19375) and was amended on August 25, 2005 (70 FR 50118). The requirements are codified at 40 CFR part 63, subpart WWWW. The Reinforced Plastic Composites Production source category includes the manufacturing of reinforced and non-reinforced plastic composite products and the production of plastic molding compounds used in the production of plastic composite products. As with boat manufacturing, reinforced plastic composite products are manufactured using resins containing styrene. Some processes use gel coats containing styrene and MMA. Operations also include mixing, tooling, and equipment cleaning. Many of the reinforced plastic composites products are manufactured using an open molding process similar to the boat manufacturing industry. As with boat manufacturing, the air emissions resulting from an open mold manufacturing process are fugitive in nature. Additionally, however, the reinforced plastic composites production processes can include pultrusion, sheet molding compound (SMC) and bulk molding compound (BMC) manufacturing, filament winding, casting, and other processes. The following paragraphs provide a brief description of some of the various processes utilized in the Reinforced Plastic Composites Production source category. Open Mold Process. The use of open molds is similar to the boat manufacturing operations, where the mold is sprayed with a layer of gel coat, or chopped glass fibers and polyester or vinylester resin. Additional layers of fiberglass and resin are added until the manufactured part is the final thickness. In addition, woven roving or mats can also be used instead of chopped fiber, in which case a spray gun would apply resin to saturate the fiberglass mat. Once the material has been applied to the mold, brushes or rollers are used to remove any entrapped air and to assure that the laminate is thoroughly “wet.” Pultrusion. Pultrusion is a continuous manufacturing process that produces parts with constant cross-sectional shapes. In a pultrusion operation, the composite is pulled through an extrusion-type die by a gripper/puller system. Reinforcing fibers are pulled through a resin bath where all materials are thoroughly impregnated with liquid resin. The wet fibrous laminate is formed to the desired geometric shape in a pre-forming section and pulled into the heated steel die. As an alternative to using a resin bath, resin can be injected into the pre-forming section (resin injection) or directly into the forming die (die injection). In the die, the resin cure is initiated by elevated temperatures. The laminate solidifies in the exact shape of the die cavity as it is being continuously pulled by the pultrusion machine. The cured product can then be cut to desired lengths. Compression Molding. Compression molding operations involve compressing the composite material under hydraulic pressure in matched metal dies and holding the configured, condensed material in the desired shape until the resin system has cured. The composite materials used in the compression molding process include SMC and BMC. SMC manufacturing includes an integrated composite material which contains all reinforcement, resin, fillers, chemical thickeners, catalyst, mold release agents, and other ingredients in an easily handled sheet. BMC manufacturing includes preparing a putty-like molding compound, which contains resins, catalysts, fillers, and reinforcements in a “ready-to-mold” form. The production output in compression molding is relatively high because the molding compounds cure rapidly in the heated mold. The materials generally yield a good finish without application of gel coat. Both surfaces of the molded product will be as smooth as the mold surface. Filament Winding. Filament winding is a composite production process for manufacturing products that are surfaces of revolution. In this process, fibers are impregnated with resin in a resin bath and wrapped around a rotating mold surface following a machine controlled geometric pattern. The product is then cured in an oven or at room temperature. All types of reinforcing fibers can be utilized in filament winding, but continuous glass fiber is most commonly used due to its high specific strength and relative low cost. Different winding patterns can be applied alone or in combination to achieve the desired strength and shape characteristics. Polymer Casting. In the polymer casting process, polymers, fillers, and additives are combined by pouring or dispensing these materials into open or partially open molds and allowing the materials to cure. Fiberglass reinforcement is generally not used in cast polymer products. In the polymer casting process, the resin matrix is catalyzed and cast onto the mold which is usually vibrated to allow air bubbles to escape. Following vibration, the product enters an exothermic stage in which the matrix's chemical reaction generates heat that causes the product to cure. In some cases, an oven is used to accelerate cure. Centrifugal Casting. In centrifugal casting, resin and fiber reinforcements (if needed) are deposited against the inside surface of a rotating mold. A resin applicator which is often located in the center of the rotating mold supplies the resin to the inside of the cast. Centrifugal force holds the material in place while the part is cured. The outside surface of the part, which is cured against the inside surface of the mold, represents the finished surface. The interior surface of the centrifugally cast part can be improved by adding an additional coat of pure resin. The Reinforced Plastic Composites Production NESHAP applies to owners/operators of reinforced plastic composites production facilities located at major sources of HAP emissions. Applicable production is limited to operations in which reinforced and/or nonreinforced plastic composites or plastic molding compounds are manufactured using thermoset resins and/or gel coats that contain styrene to produce plastic composites. Applicable operations also include cleaning, mixing, HAP-containing materials storage, and repair operations associated with the production of plastic composites. The Reinforced Plastic Composites Production NESHAP does not apply to those facilities who only repair reinforced plastic composites products. These repairs include the non-routine manufacturing of individual components or parts intended to repair a larger item. Additionally, the Reinforced Plastic Composites Production NESHAP does not apply to research and development facilities, as defined in section 112(c)(7) of the CAA. Lastly, the Reinforced Plastic Composites Production NESHAP is limited to those facilities that use greater than 1.2 tpy of thermoset resins and gel coats (combined) that contain styrene. Facilities are required to incorporate pollution-prevention techniques in their production processes. These techniques include the following: • Using raw materials containing low amounts of air toxics; • Non-atomized resin application; and • Covering open resin baths and tanks. In general, the Reinforced Plastic Composites Production NESHAP requirements apply to three groups of operations, which include the following: • Sources required to reduce HAP emissions by 95 percent; • Sources required to comply with work practice standards; and • Sources required to comply with emission limits. The applicability of these requirements is described in greater detail in the 2003 rule (68 FR 19375), and 40 CFR part 63, subpart WWWW. C. What data collection activities were conducted to support this action? For the residual risk assessment, the EPA sent out an information collection request (ICR) to nine parent companies subject to the Boat Manufacturing NESHAP, requesting information regarding the boat manufacturing process and the associated air emissions. The information requested included description of HAP-emitting processes, information on the HAP-containing materials used, estimates of emissions, and descriptions of control technologies, if present. After receiving information, as requested, from the boat manufacturing facilities surveyed, the EPA compiled the data with the intent to use the information as a reference to develop the risk assessment modeling file. The ICR information provided supplemental information regarding processes, the sources of HAP emissions, material usages, and stack information. No ICR was sent to sources in the Reinforced Plastic Composites Production source category. For both the Boat Manufacturing NESHAP RTR and the Reinforced Plastic Composites Production NESHAP RTR, the EPA used data from the 2014 National Emissions Inventory (NEI). The NEI is a database that contains information about sources that emit criteria air pollutants, their precursors, and HAP. The database includes estimates of annual air pollutant emissions from point, nonpoint, and mobile sources in the 50 states, the District of Columbia, Puerto Rico, and the Virgin Islands. The EPA collects this information and releases an updated version of the NEI database every 3 years. The NEI includes data necessary for conducting risk modeling, including annual HAP emissions estimates from individual emission points at facilities and the related emissions release parameters. The EPA used NEI emissions and supporting data as the primary data to develop the model input files for the residual risk assessments for the Boat Manufacturing and Reinforced Plastic Composites Production source categories. Additional information on the development of the modeling file for each source category can be found in Appendix 1 to the Residual Risk Assessment for the Boat Manufacturing Source Category in Support of the 2018 Risk and Technology Review Proposed Rule (Docket ID No. EPA-HQ-OAR-2016-0447) and Appendix 1 to the Residual Risk Assessment for the reinforced Plastic Composites Production Source Category in Support of the 2018 Risk and Technology Review Proposed Rule (Docket ID No. EPA-HQ-OAR-2016-0449). For both the risk modeling and technology review portion of these RTRs, the EPA visited one boat manufacturing facility and six reinforced plastic composites production facilities. During the visits, the EPA discussed process operations, compliance with the existing NESHAP, description of the emission points, process controls, unregulated emissions, and other aspects of facility operations. We used the information provided by the facilities to understand the various operations, and in our evaluation of existing controls and new developments in practices, processes, and control technologies for both source categories. The site visit reports are included as attachments to the memorandum, Technology Review for Boat Manufacturing and Reinforced Plastic Composites Production Source Category, in the docket for each source category (Docket ID No. EPA-HQ-OAR-2016-0447 for the Boat Manufacturing NESHAP and Docket ID No. EPA-HQ-OAR-2016-0449 for the Reinforced Plastic Composites Production NESHAP). For both the risk modeling and technology review, the EPA also gathered data from facility construction and operating permits regarding emission points, air pollution control devices, and process operations. We collected permits and supporting documentation from state permitting authorities through state-maintained online databases. The facility permits were also used to confirm that the facilities were major sources of HAP and were subject to the NESHAP that are the subject of these risk assessments. In certain cases, we contacted facility owners or operators to confirm and clarify the sources of emissions that were reported in the NEI. D. What other relevant background information and data are available? For the technology review portion of these RTRs, we collected information from the Reasonably Available Control Technology, Best Available Control Technology, and Lowest Achievable Emission Rate Clearinghouse (RBLC). This is a database that contains case-specific information on air pollution technologies that have been required to reduce the emissions of air pollutants from stationary sources. Under the EPA's New Source Review (NSR) program, if a facility is planning new construction or a modification that will increase the air emissions above certain defined thresholds, an NSR permit must be obtained. The RBLC promotes the sharing of information among permitting agencies and aids in case-by-case determinations for NSR permits. We examined information contained in the RBLC to determine what technologies are currently used for these source categories to reduce air emissions. Additional information about these data collection activities for the technology reviews is contained in the technology review memorandum titled Technology Review for Boat Manufacturing and Reinforced Plastic Composites Production Source Category (Docket ID No. EPA-HQ-OAR-2016-0447 for the Boat Manufacturing NESHAP and Docket ID No. EPA-HQ-OAR-2016-0449 for the Reinforced Plastic Composites Production NESHAP). III. Analytical Procedures and Decision-Making In this section, we describe the analyses performed to support the proposed decisions for the RTR and other issues addressed in this proposal. A. How do we consider risk in our decision-making? As discussed in section II.A of this preamble and in the Benzene NESHAP, in evaluating and developing standards under CAA section 112(f)(2), we apply a two-step approach to determine whether or not risks are acceptable and to determine if the standards provide an ample margin of safety to protect public health. As explained in the Benzene NESHAP, “the first step judgment on acceptability cannot be reduced to any single factor” and, thus, “[t]he Administrator believes that the acceptability of risk under section 112 is best judged on the basis of a broad set of health risk measures and information.” 54 FR 38046, September 14, 1989. Similarly, with regard to the ample margin of safety determination, “the Agency again considers all of the health risk and other health information considered in the first step. Beyond that information, additional factors relating to the appropriate level of control will also be considered, including cost and economic impacts of controls, technological feasibility, uncertainties, and any other relevant factors.” Id. The Benzene NESHAP approach provides flexibility regarding factors the EPA may consider in making determinations and how the EPA may weigh those factors for each source category. The EPA conducts a risk assessment that provides estimates of the MIR posed by the HAP emissions from each source in the source category, the hazard index (HI) for chronic exposures to HAP with the potential to cause noncancer health effects, and the hazard quotient (HQ) for acute exposures to HAP with the potential to cause noncancer health effects. 2 The assessment also provides estimates of the distribution of cancer risk within the exposed populations, cancer incidence, and an evaluation of the potential for an adverse environmental effect. The scope of the EPA's risk analysis is consistent with the EPA's response to comments on our policy under the Benzene NESHAP where the EPA explained that: 2 The MIR is defined as the cancer risk associated with a lifetime of exposure at the highest concentration of HAP where people are likely to live. The HQ is the ratio of the potential exposure to the HAP to the level at or below which no adverse chronic noncancer effects are expected; the HI is the sum of HQs for HAP that affect the same target organ or organ system. [t]he policy chosen by the Administrator permits consideration of multiple measures of health risk. Not only can the MIR figure be considered, but also incidence, the presence of non-cancer health effects, and the uncertainties of the risk estimates. In this way, the effect on the most exposed individuals can be reviewed as well as the impact on the general public. These factors can then be weighed in each individual case. This approach complies with the Vinyl Chloride mandate that the Administrator ascertain an acceptable level of risk to the public by employing his expertise to assess available data. It also complies with the Congressional intent behind the CAA, which did not exclude the use of any particular measure of public health risk from the EPA's consideration with respect to CAA section 112 regulations, and thereby implicitly permits consideration of any and all measures of health risk which the Administrator, in his judgment, believes are appropriate to determining what will `protect the public health'. See 54 FR 38057, September 14, 1989. Thus, the level of the MIR is only one factor to be weighed in determining acceptability of risk. The Benzene NESHAP explained that “an MIR of approximately one in 10 thousand should ordinarily be the upper end of the range of acceptability. As risks increase above this benchmark, they become presumptively less acceptable under CAA section 112, and would be weighed with the other health risk measures and information in making an overall judgment on acceptability. Or, the Agency may find, in a particular case, that a risk that includes an MIR less than the presumptively acceptable level is unacceptable in the light of other health risk factors.” Id. at 38045. Similarly, with regard to the ample margin of safety analysis, the EPA stated in the Benzene NESHAP that: “EPA believes the relative weight of the many factors that can be considered in selecting an ample margin of safety can only be determined for each specific source category. This occurs mainly because technological and economic factors (along with the health-related factors) vary from source category to source category.” Id. at 38061. We also consider the uncertainties associated with the various risk analyses, as discussed earlier in this preamble, in our determinations of acceptability and ample margin of safety. The EPA notes that it has not considered certain health information to date in making residual risk determinations. At this time, we do not attempt to quantify the HAP risk that may be associated with emissions from other facilities that do not include the source categories under review, mobile source emissions, natural source emissions, persistent environmental pollution, or atmospheric transformation in the vicinity of the sources in the categories. The EPA understands the potential importance of considering an individual's total exposure to HAP in addition to considering exposure to HAP emissions from the source category and facility. We recognize that such consideration may be particularly important when assessing noncancer risk, where pollutant-specific exposure health reference levels ( e.g., reference concentrations (RfCs)) are based on the assumption that thresholds exist for adverse health effects. For example, the EPA recognizes that, although exposures attributable to emissions from a source category or facility alone may not indicate the potential for increased risk of adverse noncancer health effects in a population, the exposures resulting from emissions from the facility in combination with emissions from all of the other sources ( e.g., other facilities) to which an individual is exposed may be sufficient to result in an increased risk of adverse noncancer health effects. In May 2010, the Science Advisory Board (SAB) advised the EPA “that RTR assessments will be most useful to decision makers and communities if results are presented in the broader context of aggregate and cumulative risks, including background concentrations and contributions from other sources in the area.” 3 3 Recommendations of the SAB Risk and Technology Review (RTR) Panel are provided in their report, which is available at: https://yosemite.epa.gov/sab/sabproduct.nsf/4AB3966E263D943A8525771F00668381/$File/EPA-SAB-10-007-unsigned.pdf. In response to the SAB recommendations, the EPA incorporates cumulative risk analyses into its RTR risk assessments, including those reflected in this proposal. The Agency (1) conducts facility-wide assessments, which include source category emission points, as well as other emission points within the facilities; (2) combines exposures from multiple sources in the same category that could affect the same individuals; and (3) for some persistent and bioaccumulative pollutants, analyzes the ingestion route of exposure. In addition, the RTR risk assessments consider aggregate cancer risk from all carcinogens and aggregated noncancer HQs for all noncarcinogens affecting the same target organ or target organ system. Although we are interested in placing source category and facility-wide HAP risk in the context of total HAP risk from all sources combined in the vicinity of each source, we are concerned about the uncertainties of doing so. Estimates of total HAP risk from emission sources other than those that we have studied in depth during this RTR review would have significantly greater associated uncertainties than the source category or facility-wide estimates. Such aggregate or cumulative assessments would compound those uncertainties, making the assessments too unreliable. B. How do we perform the technology review? Our technology review focuses on the identification and evaluation of developments in practices, processes, and control technologies that have occurred since the MACT standards were promulgated. Where we identify such developments, we analyze their technical feasibility, estimated costs, energy implications, and non-air environmental impacts. We also consider the emission reductions associated with applying each development. This analysis informs our decision of whether it is “necessary” to revise the emissions standards. In addition, we consider the appropriateness of applying controls to new sources versus retrofitting existing sources. For this exercise, we consider any of the following to be a “development”: • Any add-on control technology or other equipment that was not identified and considered during development of the original MACT standards; • Any improvements in add-on control technology or other equipment (that were identified and considered during development of the original MACT standards) that could result in additional emissions reduction; • Any work practice or operational procedure that was not identified or considered during development of the original MACT standards; • Any process change or pollution prevention alternative that could be broadly applied to the industry and that was not identified or considered during development of the original MACT standards; and • Any significant changes in the cost (including cost effectiveness) of applying controls (including controls the EPA considered during the development of the original MACT standards). In addition to reviewing the practices, processes, and control technologies that were considered at the time we originally developed the NESHAP, we review a variety of data sources in our investigation of potential practices, processes, or controls to consider. See sections II.C and II.D of this preamble for information on the specific data sources that were reviewed as part of the technology review. C. How do we estimate post-MACT risk posed by the source category? In this section, we provide a complete description of the types of analyses that we generally perform during the risk assessment process. In some cases, we do not perform a specific analysis because it is not relevant. For example, in the absence of emissions of HAP known to be persistent and bioaccumulative in the environment (PB-HAP), we would not perform a multipathway exposure assessment. Where we do not perform an analysis, we state that we do not and provide the reason. While we present all of our risk assessment methods, we only present risk assessment results for the analyses actually conducted (see sections IV.B and IV.G). The EPA conducts a risk assessment that provides estimates of the MIR for cancer posed by the HAP emissions from each source in the source category, the HI for chronic exposures to HAP with the potential to cause noncancer health effects, and the HQ for acute exposures to HAP with the potential to cause noncancer health effects. The assessment also provides estimates of the distribution of cancer risk within the exposed populations, cancer incidence, and an evaluation of the potential for an adverse environmental effect. The seven sections that follow this paragraph describe how we estimated emissions and conducted the risk assessment. The docket for the Boat Manufacturing NESHAP rulemaking contains the following document which provides more information on the risk assessment inputs and models: Residual Risk Assessment for Boat Manufacturing Source Category in Support of the 2018 Risk and Technology Review Proposed Rule. The docket for the Reinforced Plastic Composites Production NESHAP rulemaking contains the following document which provides more information on the risk assessment inputs and models: Residual Risk Assessment for Reinforced Plastic Composites Production Source Category in Support of the 2018 Risk and Technology Review Proposed Rule. The methods used to assess risk (as described in the seven primary steps below) are consistent with those described by the EPA in the document reviewed by a panel of the EPA's SAB in 2009; 4 and described in the SAB review report issued in 2010. They are also consistent with the key recommendations contained in that report. 4 U.S. EPA. Risk and Technology Review (RTR) Risk Assessment Methodologies: For Review by the EPA's Science Advisory Board with Case Studies—MACT I Petroleum Refining Sources and Portland Cement Manufacturing, June 2009. EPA-452/R-09-006. https://www3.epa.gov/airtoxics/rrisk/rtrpg.html. 1. How did we estimate actual emissions and identify the emissions release characteristics? The actual emissions and the emission release characteristics for each facility in each of the two source categories were obtained from the 2014 NEI. In addition, the EPA provided draft actual emissions data and stack parameters to facilities in the two source categories for review and confirmation. In some cases, facilities were contacted to confirm emissions that appeared to be outliers, that were otherwise inconsistent with our understanding of the industry, or that were associated with high risk values in our initial risk screening analyses. Where appropriate, emission values and release characteristics were corrected, based on revised stack parameter information provided by the facilities. These revisions were documented and are included in the docket for each source category. Additional information on the development of the modeling file for each source category, including the development of the actual emissions and emissions release characteristics, can be found in Appendix 1 to the Residual Risk Assessment for Boat Manufacturing Source Category in Support of the 2018 Risk and Technology Review Proposed Rule document and Appendix 1 to the Residual Risk Assessment for Reinforced Plastic Composites Production Source Category in Support of the 2018 Risk and Technology Review Proposed Rule document, located in the docket for each source category (Docket ID No. EPA-HQ-OAR-2016-0447 for the Boat Manufacturing NESHAP and Docket ID No. EPA-HQ-OAR-2016-0449 for the Reinforced Plastic Composites Production NESHAP). 2. How did we estimate MACT-allowable emissions? The available emissions data in the RTR emissions dataset include estimates of the mass of HAP emitted during a specified annual time period. These “actual” emission levels are often lower than the emission levels allowed under the requirements of the current MACT standards. The emissions allowed under the MACT standards are referred to as the “MACT-allowable” emissions. We discussed the consideration of both MACT-allowable and actual emissions in the final Coke Oven Batteries RTR (70 FR 19998-19999, April 15, 2005) and in the proposed and final Hazardous Organic NESHAP RTR (71 FR 34428, June 14, 2006, and 71 FR 76609, December 21, 2006, respectively). In those actions, we noted that assessing the risk at the MACT-allowable level is inherently reasonable since that risk reflects the maximum level facilities could emit and still comply with national emission standards. We also explained that it is reasonable to consider actual emissions, where such data are available, in both steps of the risk analysis, in accordance with the Benzene NESHAP approach. (54 FR 38044, September 14, 1989.) The MACT for each of the two source categories includes HAP limits for materials ( i.e., resin and gel coats) used during open molding operations. A majority of the facilities in both source categories use compliant materials to demonstrate compliance. The EPA's actual emissions estimates were based on the category information reported in the 2014 NEI. Since the majority of facilities use compliant materials, it is reasonable to assume that the actual emissions and the allowable emissions are equal. This is because the allowable limits of the MACT represent the HAP content of the materials being used. Further, this compliance approach is referenced in, and, therefore, required by facility permits. However, to supplement this information, and to estimate a more conservative allowable emissions multiplier, the EPA gathered current and historical publicly available category-specific data from the U.S. Census Bureau over a 5-year period (2010 to 2014). Based an analysis of the source categories, and the utilization information indicated by the U.S. Census Bureau data for both source categories, the EPA calculated allowable emissions by developing a multiplier applied to the current actual emission rates. The multiplier is based on historical data and utilization rates for each category for the years 2010 to 2014. The multiplier developed for both source categories is the ratio of the peak utilization rate to the average utilization rate for the years 2005 to 2014. Details regarding the development of the allowable multiplier are presented in the memorandum, Emissions Data for the National Emission Standards for Hazardous Air Pollutants for Boat Manufacturing and the National Emission Standards for Hazardous Air Pollutants for Reinforced Plastic Composites Production, located in the docket for each source category (Docket ID No. EPA-HQ-OAR-2016-0447 for the Boat Manufacturing NESHAP and Docket ID No. EPA-HQ-OAR-2016-0449 for the Reinforced Plastic Composites Production NESHAP). 3. How do we conduct dispersion modeling, determine inhalation exposures, and estimate individual and population inhalation risk? Both long-term and short-term inhalation exposure concentrations and health risk from the source category addressed in this proposal were estimated using the Human Exposure Model (HEM-3). 5 The HEM-3 performs three primary risk assessment activities: (1) Conducting dispersion modeling to estimate the concentrations of HAP in ambient air, (2) estimating long-term and short-term inhalation exposures to individuals residing within 50 kilometer (km) of the modeled sources, and (3) estimating individual and population-level inhalation risk using the exposure estimates and quantitative dose-response information. 5 For more information about HEM-3, go to https://www.epa.gov/fera/risk-assessment-and-modeling-human-exposure-model-hem. a. Dispersion Modeling The air dispersion model AERMOD, used by the HEM-3 model, is one of the EPA's preferred models for assessing air pollutant concentrations from industrial facilities. 6 To perform the dispersion modeling and to develop the preliminary risk estimates, HEM-3 draws on three data libraries. The first is a library of meteorological data, which is used for dispersion calculations. This library includes 1 year (2016) of hourly surface and upper air observations from 824 meteorological stations selected to provide coverage of the United States and Puerto Rico. A second library of United States Census Bureau census block 7 internal point locations and populations provides the basis of human exposure calculations (U.S. Census, 2010). In addition, for each census block, the census library includes the elevation and controlling hill height, which are also used in dispersion calculations. A third library of pollutant-specific dose-response values is used to estimate health risk. These are discussed below. 6 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). 7 A census block is the smallest geographic area for which census statistics are tabulated. b. Risk From Chronic Exposure to HAP In developing the risk assessment for chronic exposures, we use the estimated annual average ambient air concentrations of each HAP emitted by each source in the source category. The HAP air concentrations at each nearby census block centroid located within 50 km of the facility are a surrogate for the chronic inhalation exposure concentration for all the people who reside in that census block. A distance of 50 km is consistent with both the analysis supporting the 1989 Benzene NESHAP (54 FR 38044, September 14, 1989) and the limitations of Gaussian dispersion models, including AERMOD. For each facility, we calculate the MIR as the cancer risk associated with a continuous lifetime (24 hours per day, 7 days per week, 52 weeks per year, 70 years) exposure to the maximum concentration at the centroid of each inhabited census block. We calculate individual cancer risk by multiplying the estimated lifetime exposure to the ambient concentration of each HAP (in micrograms per cubic meter (μg/m 3 )) by its unit risk estimate (URE). The URE is an upper-bound estimate of an individual's incremental risk of contracting cancer over a lifetime of exposure to a concentration of 1 microgram of the pollutant per cubic meter of air. For residual risk assessments, we generally use UREs from the EPA's Integrated Risk Information System (IRIS). For carcinogenic pollutants without IRIS values, we look to other reputable sources of cancer dose-response values, often using California EPA (CalEPA) UREs, where available. In cases where new, scientifically credible 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 the EPA, we may use such dose-response values in place of, or in addition to, other values, if appropriate. The pollutant-specific dose-response values used to estimate health risk are available at https://www.epa.gov/fera/dose-response-assessment-assessing-health-risks-associated-exposure-hazardous-air-pollutants. In March 2018, the International Agency for Research on Cancer (IARC) revised the weight of evidence classification of styrene to Group 2A—“probably carcinogenic to humans.” Presently, the EPA's IRIS database and other reputable peer-reviewed sources of cancer dose-response values are not available to assess cancer risks for this pollutant. 8 8 https://monographs.iarc.fr/list-of-classifications-volumes/. To estimate individual lifetime cancer risks associated with exposure to HAP emissions from each facility in the source category, we sum the risks for each of the carcinogenic HAP 9 emitted by the modeled facility. We estimate cancer risk at every census block within 50 km of every facility in the source category. The MIR is the highest individual lifetime cancer risk estimated for any of those census blocks. In addition to calculating the MIR, we estimate the distribution of individual cancer risks for the source category by summing the number of individuals within 50 km of the sources whose estimated risk falls within a specified risk range. We also estimate annual cancer incidence by multiplying the estimated lifetime cancer risk at each census block by the number of people residing in that block, summing results for all of the census blocks, and then dividing this result by a 70-year lifetime. 9 The EPA's 2005 Guidelines for Carcinogen Risk Assessment classifies carcinogens as: “carcinogenic to humans,” “likely to be carcinogenic to humans,” and “suggestive evidence of carcinogenic potential.” These classifications also coincide with the terms “known carcinogen, probable carcinogen, and possible carcinogen,” respectively, which are the terms advocated in the EPA's Guidelines for Carcinogen Risk Assessment, published in 1986 (51 FR 33992, September 24, 1986). In August 2000, the document, Supplemental Guidance for Conducting Health Risk Assessment of Chemical Mixtures (EPA/630/R-00/002), was published as a supplement to the 1986 document. Copies of both documents can be obtained from https://cfpub.epa.gov/ncea/risk/recordisplay.cfm?deid=20533&CFID=70315376&CFTOKEN=71597944. Summing the risk of these individual compounds to obtain the cumulative cancer risk is an approach that was recommended by the EPA's SAB in their 2002 peer review of the EPA's National Air Toxics Assessment (NATA) titled NATA—Evaluating the National-scale Air Toxics Assessment 1996 Data—an SAB Advisory, available at https://yosemite.epa.gov/sab/sabproduct.nsf/214C6E915BB04E14852570CA007A682C/$File/ecadv02001.pdf. To assess the risk of noncancer health effects from chronic exposure to HAP, we calculate either an HQ or a target organ-specific hazard index (TOSHI). We calculate an HQ when a single noncancer HAP is emitted. Where more than one noncancer HAP is emitted, we sum the HQ for each of the HAP that affects a common target organ or target organ system to obtain a TOSHI. The HQ is the estimated exposure divided by the chronic noncancer dose-response value, which is a value selected from one of several sources. The preferred chronic noncancer dose-response value is the EPA RfC, defined as “an estimate (with uncertainty spanning perhaps an order of magnitude) of a continuous inhalation exposure to the human population (including sensitive subgroups) that is likely to be without an appreciable risk of deleterious effects during a lifetime” ( https://iaspub.epa.gov/sor_internet/registry/termreg/searchandretrieve/glossariesandkeywordlists/search.do?details=&vocabName=IRIS%20Glossary ). In cases where an RfC from the EPA's IRIS is not available or where the EPA determines that using a value other than the RfC is appropriate, the chronic noncancer dose-response value can be a value from the following prioritized sources, which define their dose-response values similarly to the EPA: (1) The Agency for Toxic Substances and Disease Registry (ATSDR) Minimum Risk Level ( https://www.atsdr.cdc.gov/mrls/index.asp ); (2) the CalEPA Chronic Reference Exposure Level (REL) ( https://oehha.ca.gov/air/crnr/notice-adoption-air-toxics-hot-spots-program-guidance-manual-preparation-health-risk-0 ); or (3), as noted above, a scientifically credible dose-response value that has been developed in a manner consistent with the EPA guidelines and has undergone a peer review process similar to that used by the EPA. The pollutant-specific dose-response values used to estimate health risks are available at https://www.epa.gov/fera/dose-response-assessment-assessing-health-risks-associated-exposure-hazardous-air-pollutants. c. Risk From Acute Exposure to HAP That May Cause Health Effects Other Than Cancer For each HAP for which appropriate acute inhalation dose-response values are available, the EPA also assesses the potential health risks due to acute exposure. For these assessments, the EPA makes conservative assumptions about emission rates, meteorology, and exposure location. We use the peak hourly emission rate, 10 worst-case dispersion conditions, and, in accordance with our mandate under section 112 of the CAA, the point of highest off-site exposure to assess the potential risk to the maximally exposed individual. 10 In the absence of hourly emission data, we develop estimates of maximum hourly emission rates by multiplying the average actual annual emissions rates by a factor to account for variability. This is documented in Residual Risk Assessment for Boat Manufacturing Source Category in Support of the 2018 Risk and Technology Review Proposed Rule document and the Residual Risk Assessment for Reinforced Plastic Composites Production Source Category in Support of the 2018 Risk and Technology Review Proposed Rule, and in Appendix 5 of the report: Analysis of Data on Short-term Emission Rates Relative to Long-term Emission Rates. Both are available in the docket for this rulemaking. To characterize the potential health risks associated with estimated acute inhalation exposures to a HAP, we generally use multiple acute dose-response values, including acute RELs, acute exposure guideline levels (AEGLs), and emergency response planning guidelines (ERPG) for 1-hour exposure durations), if available, to calculate acute HQs. The acute HQ is calculated by dividing the estimated acute exposure by the acute dose-response value. For each HAP for which acute dose-response values are available, the EPA calculates acute HQs. An acute REL is defined as “the concentration level at or below which no adverse health effects are anticipated for a specified exposure duration.” 11 Acute RELs are based on the most sensitive, relevant, adverse health effect reported in the peer-reviewed medical and toxicological literature. They are designed to protect the most sensitive individuals in the population through the inclusion of margins of safety. Because margins of safety are incorporated to address data gaps and uncertainties, exceeding the REL does not automatically indicate an adverse health impact. AEGLs represent threshold exposure limits for the general public and are applicable to emergency exposures ranging from 10 minutes to 8 hours. 12 They are guideline levels for “once-in-a-lifetime, short-term exposures to airborne concentrations of acutely toxic, high-priority chemicals.” Id. at 21. The AEGL-1 is specifically defined as “the airborne concentration (expressed as parts per million (ppm) or milligrams per cubic meter (mg/m 3 )) of a substance above which it is predicted that the general population, including susceptible individuals, could experience notable discomfort, irritation, or certain asymptomatic nonsensory effects. However, the effects are not disabling and are transient and reversible upon cessation of exposure.” The document also notes that “Airborne concentrations below AEGL-1 represent exposure levels that can produce mild and progressively increasing but transient and nondisabling odor, taste, and sensory irritation or certain asymptomatic, nonsensory effects.” Id. AEGL-2 are defined as “the airborne concentration (expressed as parts per million or milligrams per cubic meter) of a substance above which it is predicted that the general population, including susceptible individuals, could experience irreversible or other serious, long-lasting adverse health effects or an impaired ability to escape.” Id. 11 CalEPA issues acute RELs as part of its Air Toxics Hot Spots Program, and the 1-hour and 8-hour values are documented in Air Toxics Hot Spots Program Risk Assessment Guidelines, Part I, The Determination of Acute Reference Exposure Levels for Airborne Toxicants, which is available at https://oehha.ca.gov/air/general-info/oehha-acute-8-hour-and-chronic-reference-exposure-level-rel-summary. 12 National Academy of Sciences, 2001. Standing Operating Procedures for Developing Acute Exposure Levels for Hazardous Chemicals, page 2. Available at https://www.epa.gov/sites/production/files/2015-09/documents/sop_final_standing_operating_procedures_2001.pdf. Note that the National Advisory Committee for Acute Exposure Guideline Levels for Hazardous Substances ended in October 2011, but the AEGL program continues to operate at the EPA and works with the National Academies to publish final AEGLs ( https://www.epa.gov/aegl ). ERPGs are “developed for emergency planning and are intended as health-based guideline concentrations for single exposures to chemicals.” 13 Id. at 1. The ERPG-1 is defined as “the maximum airborne concentration below which it is believed that nearly all individuals could be exposed for up to 1 hour without experiencing other than mild transient adverse health effects or without perceiving a clearly defined, objectionable odor.” Id. at 2. Similarly, the ERPG-2 is defined as “the maximum airborne concentration below which it is believed that nearly all individuals could be exposed for up to one hour without experiencing or developing irreversible or other serious health effects or symptoms which could impair an individual's ability to take protective action.” Id. at 1. 13 ERPGS Procedures and Responsibilities. March 2014. American Industrial Hygiene Association. Available at: https://www.aiha.org/get-involved/AIHAGuidelineFoundation/EmergencyResponsePlanningGuidelines/Documents/ERPG%20Committee%20Standard%20Operating%20Procedures%20%20-%20March%202014%20Revision%20%28Updated%2010-2-2014%29.pdf. An acute REL for 1-hour exposure durations is typically lower than its corresponding AEGL-1 and ERPG-1. Even though their definitions are slightly different, AEGL-1s are often the same as the corresponding ERPG-1s, and AEGL-2s are often equal to ERPG-2s. The maximum HQs from our acute inhalation screening risk assessment typically result when we use the acute REL for a HAP. In cases where the maximum acute HQ exceeds 1, we also report the HQ based on the next highest acute dose-response value (usually the AEGL-1 and/or the ERPG-1). For the Boat Manufacturing and Reinforced Plastic Composites Production source categories, the hourly emission rates of the various HAP will not have high variability during the manufacturing processes and, therefore, are expected to remain constant over the time the process is operating. This is because the application of resins and gel coats, adhesives, foam, and other regulated sources of HAP in the source categories are most efficient when applied at a constant pressure, with maximum coverage, with the most efficient spray patterns and number of passes made by the operator. Based on this information, the default acute emission factor of 10 times the annual hourly emission rate is not reasonable for the Boat Manufacturing and Reinforced Plastic Composites Production source categories. However, many facilities do not operate three shifts a day. Therefore, a days worth of emissions may occur over a time period of as little as 8 hours. With this understanding of the processes, we, therefore, assumed the maximum rate of emissions would occur in this 8-hour period each day. Based on this information, an acute emission factor of 3 was calculated to be applied to actual annual hourly emission rates, derived from the ratio of an 8-hour shift in a 24-hour day. A further discussion of why this factor was chosen can be found in the memorandum, Emissions Data for the National Emission Standards for Hazardous Air Pollutants for Boat Manufacturing and the National Emission Standards for Hazardous Air Pollutants for Reinforced Plastic Composites Production, available in the dockets for this rulemaking (Docket ID No. EPA-HQ-OAR-2016-0447 for the Boat Manufacturing NESHAP and Docket ID No. EPA-HQ-OAR-2016-0449 for the Reinforced Plastic Composites Production NESHAP). In our acute inhalation screening risk assessment, acute impacts are deemed negligible for HAP for which acute HQs are less than or equal to 1 (even under the conservative assumptions of the screening assessment), and no further analysis is performed for these HAP. In cases where an acute HQ from the screening step is greater than 1, we consider additional site-specific data to develop a more refined estimate of the potential for acute exposures of concern. These refinements are discussed more fully in the Residual Risk Assessment for Boat Manufacturing Source Category in Support of the 2018 Risk and Technology Review Proposed Rule document and the Residual Risk Assessment for Reinforced Plastic Composites Production Source Category in Support of the 2018 Risk and Technology Review Proposed Rule document, which are available in the docket for each of the respective source categories. 4. How do we conduct the multipathway exposure and risk screening assessment? The EPA conducts a tiered screening assessment examining the potential for significant human health risks due to exposures via routes other than inhalation ( i.e., ingestion). We first determine whether any sources in the source categories emit any HAP known to be PB-HAP, as identified in the EPA's Air Toxics Risk Assessment Library (See Volume 1, Appendix D, at https://www2.epa.gov/fera/risk-assessment-and-modeling-air-toxics-risk-assessment-reference-library ). For the Boat Manufacturing source category, we identified PB-HAP emissions of arsenic, polycyclic organic matter (POM), and cadmium, and for the Reinforced Plastic Composites Production source category, we identified PB-HAP emissions of arsenic, POM, cadmium, and mercury, so we proceeded to the next step of the evaluation. In this step, we determine whether the facility-specific emission rates of the emitted PB-HAP are large enough to create the potential for significant human health risk through ingestion exposure under reasonable worst-case conditions. To facilitate this step, we use previously developed screening threshold emission rates for several PB-HAP that are based on a hypothetical upper-end screening exposure scenario developed for use in conjunction with the EPA's Total Risk Integrated Methodology.Fate, Transport, and Ecological Exposure (TRIM.FaTE) model. The PB-HAP with screening threshold emission rates are arsenic compounds, cadmium compounds, chlorinated dibenzodioxins and furans, mercury compounds, and POM. Based on the EPA estimates of toxicity and bioaccumulation potential, the pollutants above represent a conservative list for inclusion in multipathway risk assessments for RTR rules. (See Volume 1, Appendix D at https://www.epa.gov/sites/production/files/201308/documents/volume_1_reflibrary.pdf ). In the assessments for the Boat Manufacturing source category, and for the Reinforced Plastic Composites Production source category, we compare the facility-specific emission rates of these PB-HAP to the screening threshold emission rates for each PB-HAP to assess the potential for significant human health risks via the ingestion pathway. We call this application of the TRIM.FaTE model the Tier 1 screening assessment. The ratio of a facility's actual emission rate to the Tier 1 screening threshold emission rate is a “screening value.” We derive the Tier 1 screening threshold emission rates for these PB-HAP (other than lead compounds) to correspond to a maximum excess lifetime cancer risk of 1-in-1 million ( i.e., for arsenic compounds, polychlorinated dibenzodioxins and furans and POM) or, for HAP that cause noncancer health effects ( i.e., cadmium compounds and mercury compounds), a maximum HQ of 1. If the emission rate of any one PB-HAP or combination of carcinogenic PB-HAP in the Tier 1 screening assessment exceeds the Tier 1 screening threshold emission rate for any facility ( i.e., the screening value is greater than 1), we conduct a second screening assessment, which we call the Tier 2 screening assessment. In the Tier 2 screening assessment, the location of each facility that exceeds a Tier 1 screening threshold emission rate is used to refine the assumptions associated with the Tier 1 fisher and farmer exposure scenarios at that facility. A key assumption in the Tier 1 screening assessment is that a lake and/or farm is located near the facility. As part of the Tier 2 screening assessment, we use a United States Geological Survey (USGS) database to identify actual waterbodies within 50 km of each facility. We also examine the differences between local meteorology near the facility and the meteorology used in the Tier 1 screening assessment. We then adjust the previously-developed Tier 1 screening threshold emission rates for each PB-HAP for each facility based on an understanding of how exposure concentrations estimated for the screening scenario change with the use of local meteorology and USGS waterbody data. If the PB-HAP emission rates for a facility exceed the Tier 2 screening threshold emission rates and data are available, we may conduct a Tier 3 screening assessment. If PB-HAP emission rates do not exceed a Tier 2 screening value of 1, we consider those PB-HAP emissions to pose risks below a level of concern. There are several analyses that can be included in a Tier 3 screening assessment, depending upon the extent of refinement warranted, including validating that the lakes are fishable, considering plume-rise to estimate emissions lost above the mixing layer, and considering hourly effects of meteorology and plume rise on chemical fate and transport. If the Tier 3 screening assessment indicates that risks above levels of concern cannot be ruled out, the EPA may further refine the screening assessment through a site-specific assessment. In evaluating the potential multipathway risk from emissions of lead compounds reported by both source categories, rather than developing a screening threshold emission rate, we compare maximum estimated chronic inhalation exposure concentrations to the level of the current National Ambient Air Quality Standard (NAAQS) for lead. 14 Values below the level of the primary (health-based) lead NAAQS are considered to have a low potential for multipathway risk. 14 In doing so, the EPA notes that the legal standard for a primary NAAQS—that a standard is requisite to protect public health and provide an adequate margin of safety (CAA section 109(b))—differs from the CAA section 112(f) standard (requiring, among other things, that the standard provide an “ample margin of safety to protect public health”). However, the primary lead NAAQS is a reasonable measure of determining risk acceptability ( i.e., the first step of the Benzene NESHAP analysis) since it is designed to protect the most susceptible group in the human population—children, including children living near major lead emitting sources. 73 FR 67002/3; 73 FR 67000/3; 73 FR 67005/1. In addition, applying the level of the primary lead NAAQS at the risk acceptability step is conservative, since that primary lead NAAQS reflects an adequate margin of safety. For further information on the multipathway assessment approach, see the Residual Risk Assessment for Boat Manufacturing Source Category in Support of the 2018 Risk and Technology Review Proposed Rule document and the Residual Risk Assessment for Reinforced Plastic Composites Production Source Category in Support of the 2018 Risk and Technology Review Proposed Rule document, which are available in the respective dockets for the source categories in this action. 5. How do we conduct the environmental risk screening assessment? a. Adverse Environmental Effect, Environmental HAP, and Ecological Benchmarks The EPA conducts a screening assessment to examine the potential for an adverse environmental effect as required under section 112(f)(2)(A) of the CAA. Section 112(a)(7) of the CAA defines “adverse environmental effect” as “any significant and widespread adverse effect, which may reasonably be anticipated, to wildlife, aquatic life, or other natural resources, including adverse impacts on populations of endangered or threatened species or significant degradation of environmental quality over broad areas.” The EPA focuses on eight HAP, which are referred to as “environmental HAP,” in its screening assessment: Six PB-HAP and two acid gases. The PB-HAP included in the screening assessment are arsenic compounds, cadmium compounds, dioxins/furans, POM, mercury (both inorganic mercury and methyl mercury), and lead compounds. The acid gases included in the screening assessment are hydrochloric acid (HCl) and hydrogen fluoride (HF). HAP that persist and bioaccumulate are of particular environmental concern because they accumulate in the soil, sediment, and water. The acid gases, HCl and HF, are included due to their well-documented potential to cause direct damage to terrestrial plants. In the environmental risk screening assessment, we evaluate the following four exposure media: Terrestrial soils, surface water bodies (includes water-column and benthic sediments), fish consumed by wildlife, and air. Within these four exposure media, we evaluate nine ecological assessment endpoints, which are defined by the ecological entity and its attributes. For PB-HAP (other than lead), both community-level and population-level endpoints are included. For acid gases, the ecological assessment evaluated is terrestrial plant communities. An ecological benchmark represents a concentration of HAP that has been linked to a particular environmental effect level. For each environmental HAP, we identified the available ecological benchmarks for each assessment endpoint. We identified, where possible, ecological benchmarks at the following effect levels: Probable effect levels, lowest-observed-adverse-effect level, and no-observed-adverse-effect level. In cases where multiple effect levels were available for a particular PB-HAP and assessment endpoint, we use all of the available effect levels to help us to determine whether ecological risks exist and, if so, whether the risks could be considered significant and widespread. For further information on how the environmental risk screening assessment was conducted, including a discussion of the risk metrics used, how the environmental HAP were identified, and how the ecological benchmarks were selected, see Appendix 9 of the Residual Risk Assessment for Boat Manufacturing Source Category in Support of the 2018 Risk and Technology Review Proposed Rule document and the Residual Risk Assessment for Reinforced Plastic Composites Production Source Category in Support of the 2018 Risk and Technology Review Proposed Rule document, which are available in the docket for the source categories in this action. b. Environmental Risk Screening Methodology For the environmental risk screening assessment, the EPA first determined whether any facilities in the Boat Manufacturing or Reinforced Plastic Composites Production source categories emitted any of the environmental HAP. For the Boat Manufacturing source category, we identified emissions of arsenic, POM, cadmium, and HCl. For the Reinforced Plastic Composites Production source category, we identified emissions of arsenic, POM, cadmium, mercury, and HCl. Because one or more of the environmental HAP evaluated above are emitted by at least one facility in the source categories, we proceeded to the second step of the evaluation. c. PB-HAP Methodology The environmental screening assessment includes six PB-HAP, arsenic compounds, cadmium compounds, dioxins/furans, POM, mercury (both inorganic mercury and methyl mercury), and lead compounds. With the exception of lead, the environmental risk screening assessment for PB-HAP consists of three tiers. The first tier of the environmental risk screening assessment uses the same health-protective conceptual model that is used for the Tier 1 human health screening assessment. TRIM.FaTE model simulations were used to back-calculate Tier 1 screening threshold emission rates. The screening threshold emission rates represent the emission rate in tpy that results in media concentrations at the facility that equal the relevant ecological benchmark. To assess emissions from each facility in the category, the reported emission rate for each PB-HAP was compared to the Tier 1 screening threshold emission rate for that PB-HAP for each assessment endpoint and effect level. If emissions from a facility do not exceed the Tier 1 screening threshold emission rate, the facility “passes” the screening assessment, and, therefore, is not evaluated further under the screening approach. If emissions from a facility exceed the Tier 1 screening threshold emission rate, we evaluate the facility further in Tier 2. In Tier 2 of the environmental screening assessment, the screening threshold emission rates are adjusted to account for local meteorology and the actual location of lakes in the vicinity of facilities that did not pass the Tier 1 screening assessment. For soils, we evaluate the average soil concentration for all soil parcels within a 7.5-km radius for each facility and PB-HAP. For the water, sediment, and fish tissue concentrations, the highest value for each facility for each pollutant is used. If emission concentrations from a facility do not exceed the Tier 2 screening threshold emission rate, the facility “passes” the screening assessment and typically is not evaluated further. If emissions from a facility exceed the Tier 2 screening threshold emission rate, we evaluate the facility further in Tier 3. As in the multipathway human health risk assessment, in Tier 3 of the environmental screening assessment, we examine the suitability of the lakes around the facilities to support life and remove those that are not suitable ( e.g., lakes that have been filled in or are industrial ponds), adjust emissions for plume-rise, and conduct hour-by-hour time-series assessments. If these Tier 3 adjustments to the screening threshold emission rates still indicate the potential for an adverse environmental effect ( i.e., facility emission rate exceeds the screening threshold emission rate), we may elect to conduct a more refined assessment using more site-specific information. If, after additional refinement, the facility emission rate still exceeds the screening threshold emission rate, the facility may have the potential to cause an adverse environmental effect. To evaluate the potential for an adverse environmental effect from lead, we compared the average modeled air concentrations (from HEM-3) of lead around each facility in the source category to the level of the secondary NAAQS for lead. The secondary lead NAAQS is a reasonable means of evaluating environmental risk because it is set to provide substantial protection against adverse welfare effects which can include “effects on soils, water, crops, vegetation, man-made materials, animals, wildlife, weather, visibility and climate, damage to and deterioration of property, and hazards to transportation, as well as effects on economic values and on personal comfort and well-being.” d. Acid Gas Environmental Risk Methodology The environmental screening assessment for acid gases evaluates the potential phytotoxicity and reduced productivity of plants due to chronic exposure to HF and HCl. The environmental risk screening methodology for acid gases is a single-tier screening assessment that compares modeled ambient air concentrations (from AERMOD) to the ecological benchmarks for each acid gas. To identify a potential adverse environmental effect (as defined in section 112(a)(7) of the CAA) from emissions of HF and HCl, we evaluate the following metrics: The size of the modeled area around each facility that exceeds the ecological benchmark for each acid gas, in acres and km 2 ; the percentage of the modeled area around each facility that exceeds the ecological benchmark for each acid gas; and the area-weighted average screening value around each facility (calculated by dividing the area-weighted average concentration over the 50-km modeling domain by the ecological benchmark for each acid gas). For further information on the environmental screening assessment approach, see Appendix 9 of the Residual Risk Assessment for Boat Manufacturing Source Category in Support of the 2018 Risk and Technology Review Proposed Rule document and the Residual Risk Assessment for Reinforced Plastic Composites Production Source Category in Support of the 2018 Risk and Technology Review Proposed Rule document, which are available in the docket for the source categories in this action. 6. How do we conduct facility-wide assessments? To put the source category risks in context, we typically examine the risks from the entire “facility,” where the facility includes all HAP-emitting operations within a contiguous area and under common control. In other words, we examine the HAP emissions not only from the source category emission points of interest, but also emissions of HAP from all other emission sources at the facility for which we have data. For the source categories in this action, we conducted the facility-wide assessment using datasets compiled from the 2014 NEI. The source category records of that NEI dataset were removed, evaluated, and updated as described in section II.C of this preamble: What data collection activities were conducted to support this action? Once a quality assured source category dataset was available, it was placed back with the remaining records from the NEI for that facility. The facility-wide file was then used to analyze risks due to the inhalation of HAP that are emitted “facility-wide” for the populations residing within 50 km of each facility, consistent with the methods used for the source category analysis described above. For these facility-wide risk analyses, the modeled source category risks were compared to the facility-wide risks to determine the portion of the facility-wide risks that could be attributed to the source category addressed in this proposal. We also specifically examined the facility that was associated with the highest estimate of risk and determined the percentage of that risk attributable to the source category of interest. The Residual Risk Assessment for Boat Manufacturing Source Category in Support of the 2018 Risk and Technology Review Proposed Rule document and the Residual Risk Assessment for Reinforced Plastic Composites Production Source Category in Support of the 2018 Risk and Technology Review Proposed Rule document, available through the docket for the source categories in this action, provides the methodology and results of the facility-wide analyses, including all facility-wide risks and the percentage of source category contribution to facility-wide risks. 7. How do we consider uncertainties in risk assessment? Uncertainty and the potential for bias are inherent in all risk assessments, including those performed for this proposal. Although uncertainty exists, we believe that our approach, which used conservative tools and assumptions, ensures that our decisions are health and environmentally protective. A brief discussion of the uncertainties in the RTR emissions datasets, dispersion modeling, inhalation exposure estimates, and dose-response relationships follows below. Also included are those uncertainties specific to our acute screening assessments, multipathway screening assessments, and our environmental risk screening assessments. A more thorough discussion of these uncertainties is included in the Residual Risk Assessment for Boat Manufacturing Source Category in Support of the 2018 Risk and Technology Review Proposed Rule document and the Residual Risk Assessment for Reinforced Plastic Composites Production Source Category in Support of the 2018 Risk and Technology Review Proposed Rule document, which are available in the source category dockets for this action. a. Uncertainties in the RTR Emissions Dataset Although the development of the RTR emissions datasets involved quality assurance/quality control processes, the accuracy of emissions values will vary depending on the source of the data, the degree to which data are incomplete or missing, the degree to which assumptions made to complete the datasets are accurate, errors in emission estimates, and other factors. The emission estimates considered in the analysis for each source category generally are annual totals for 2014, and they do not reflect short-term fluctuations during the course of a year or variations from year to year. The estimates of peak hourly emission rates for the acute effects screening assessment were based on an emission adjustment factor applied to the average annual hourly emission rates, which are intended to account for emission fluctuations due to normal facility operations. b. Uncertainties in Dispersion Modeling We recognize there is uncertainty in ambient concentration estimates associated with any model, including the EPA's recommended regulatory dispersion model, AERMOD. In using a model to estimate ambient pollutant concentrations, the user chooses certain options to apply. For RTR assessments, we select some model options that have the potential to overestimate ambient air concentrations ( e.g., not including plume depletion or pollutant transformation). We select other model options that have the potential to underestimate ambient impacts ( e.g., not including building downwash). Other options that we select have the potential to either under- or overestimate ambient levels ( e.g., meteorology and receptor locations). On balance, considering the directional nature of the uncertainties commonly present in ambient concentrations estimated by dispersion models, the approach we apply in the RTR assessments should yield unbiased estimates of ambient HAP concentrations. We also note that the selection of meteorology dataset location could have an impact on the risk estimates. As we continue to update and expand our library of meteorological station data used in our risk assessments, we expect to reduce this variability. c. Uncertainties in Inhalation Exposure Assessment Although every effort is made to identify all of the relevant facilities and emission points, as well as to develop accurate estimates of the annual emission rates for all relevant HAP, the uncertainties in our emission inventory likely dominate the uncertainties in the exposure assessment. Some uncertainties in our exposure assessment include human mobility, using the centroid of each census block, assuming lifetime exposure, and assuming only outdoor exposures. For most of these factors, there is neither an under nor overestimate when looking at the maximum individual risk or the incidence, but the shape of the distribution of risks may be affected. With respect to outdoor exposures, actual exposures may not be as high if people spend time indoors, especially for very reactive pollutants or larger particles. For all factors, we reduce uncertainty when possible. For example, with respect to census-block centroids, we analyze large blocks using aerial imagery and adjust locations of the block centroids to better represent the population in the blocks. We also add additional receptor locations where the population of a block is not well represented by a single location. d. Uncertainties in Dose-Response Relationships There are uncertainties inherent in the development of the dose-response values used in our risk assessments for cancer effects from chronic exposures and noncancer effects from both chronic and acute exposures. Some uncertainties are generally expressed quantitatively, and others are generally expressed in qualitative terms. We note, as a preface to this discussion, a point on dose-response uncertainty that is stated in the EPA's 2005 Guidelines for Carcinogen Risk Assessment; namely, that “the primary goal of EPA actions is protection of human health; accordingly, as an Agency policy, risk assessment procedures, including default options that are used in the absence of scientific data to the contrary, should be health protective” (the EPA's 2005 Guidelines for Carcinogen Risk Assessment, page 1-7). This is the approach followed here as summarized in the next paragraphs. Cancer UREs used in our risk assessments are those that have been developed to generally provide an upper bound estimate of risk. 15 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. 16 Chronic noncancer RfC and reference dose values represent chronic exposure levels that are intended to be health-protective levels. To derive dose-response values that are intended to be “without appreciable risk,” the methodology relies upon an uncertainty factor (UF) approach, 17 which considers uncertainty, variability, and gaps in the available data. The UFs are applied to derive dose-response values that are intended to protect against appreciable risk of deleterious effects. 15 IRIS glossary ( https://ofmpub.epa.gov/sor_internet/registry/termreg/searchandretrieve/glossariesandkeywordlists/search.do?details=&glossaryName=IRIS%20Glossary ). 16 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. 17 See A Review of the Reference Dose and Reference Concentration Processes, U.S. EPA, December 2002, and Methods for Derivation of Inhalation Reference Concentrations and Application of Inhalation Dosimetry, U.S. EPA, 1994. Many of the UFs used to account for variability and uncertainty in the development of acute dose-response values are quite similar to those developed for chronic durations. Additional adjustments are often applied to account for uncertainty in extrapolation from observations at one exposure duration ( e.g., 4 hours) to derive an acute dose-response value at another exposure duration ( e.g., 1 hour). Not all acute dose-response values are developed for the same purpose, and care must be taken when interpreting the results of an acute assessment of human health effects relative to the dose-response value or values being exceeded. Where relevant to the estimated exposures, the lack of acute dose-response values at different levels of severity should be factored into the risk characterization as potential uncertainties. Uncertainty also exists in the selection of ecological benchmarks for the environmental risk screening assessment. We established a hierarchy of preferred benchmark sources to allow selection of benchmarks for each environmental HAP at each ecological assessment endpoint. We searched for benchmarks for three effect levels ( i.e., no-effects level, threshold-effect level, and probable effect level), but not all combinations of ecological assessment/environmental HAP had benchmarks for all three effect levels. Where multiple effect levels were available for a particular HAP and assessment endpoint, we used all of the available effect levels to help us determine whether risk exists and whether the risk could be considered significant and widespread. Although we make every effort to identify appropriate human health effect dose-response values for all pollutants emitted by the sources in this risk assessment, some HAP emitted by these source categories are lacking dose-response assessments. Accordingly, these pollutants cannot be included in the quantitative risk assessment, which could result in quantitative estimates understating HAP risk. To help to alleviate this potential underestimate, where we conclude similarity with a HAP for which a dose-response value is available, we use that value as a surrogate for the assessment of the HAP for which no value is available. To the extent use of surrogates indicates appreciable risk, we may identify a need to increase priority for an IRIS assessment for that substance. We additionally note that, generally speaking, HAP of greatest concern due to environmental exposures and hazard are those for which dose-response assessments have been performed, reducing the likelihood of understating risk. Further, HAP not included in the quantitative assessment are assessed qualitatively and considered in the risk characterization that informs the risk management decisions, including consideration of HAP reductions achieved by various control options. For a group of compounds that are unspeciated ( e.g., glycol ethers), we conservatively use the most protective dose-response value of an individual compound in that group to estimate risk. Similarly, for an individual compound in a group ( e.g., ethylene glycol diethyl ether) that does not have a specified dose-response value, we also apply the most protective dose-response value from the other compounds in the group to estimate risk. e. Uncertainties in Acute Inhalation Screening Assessments In addition to the uncertainties highlighted above, there are several factors specific to the acute exposure assessment that the EPA conducts as part of the risk review under section 112 of the CAA. The accuracy of an acute inhalation exposure assessment depends on the simultaneous occurrence of independent factors that may vary greatly, such as hourly emissions rates, meteorology, and the presence of humans at the location of the maximum concentration. In the acute screening assessment that we conduct under the RTR program, we assume that peak emissions from the source category and worst-case meteorological conditions co-occur, thus, resulting in maximum ambient concentrations. These two events are unlikely to occur at the same time, making these assumptions conservative. We then include the additional assumption that a person is located at this point during this same time period. For this source category, these assumptions would tend to be worst-case actual exposures, as it is unlikely that a person would be located at the point of maximum exposure during the time when peak emissions and worst-case meteorological conditions occur simultaneously. f. Uncertainties in the Multipathway and Environmental Risk Screening Assessments For each source category, we generally rely on site-specific levels of PB-HAP or environmental HAP emissions to determine whether a refined assessment of the impacts from multipathway exposures is necessary or whether it is necessary to perform an environmental screening assessment. This determination is based on the results of a three-tiered screening assessment that relies on the outputs from models—TRIM.FaTE and AERMOD—that estimate environmental pollutant concentrations and human exposures for five PB-HAP (dioxins, POM, mercury, cadmium, and arsenic) and two acid gases (HF and HCl). For lead, we use AERMOD to determine ambient air concentrations, which are then compared to the secondary NAAQS standard for lead. Two important types of uncertainty associated with the use of these models in RTR risk assessments and inherent to any assessment that relies on environmental modeling are model uncertainty and input uncertainty. 18 18 In the context of this discussion, the term “uncertainty” as it pertains to exposure and risk encompasses both variability in the range of expected inputs and screening results due to existing spatial, temporal, and other factors, as well as uncertainty in being able to accurately estimate the true result. Model uncertainty concerns whether the model adequately represents the actual processes ( e.g., movement and accumulation) that might occur in the environment. For example, does the model adequately describe the movement of a pollutant through the soil? This type of uncertainty is difficult to quantify. However, based on feedback received from previous EPA SAB reviews and other reviews, we are confident that the models used in the screening assessments are appropriate and state-of-the-art for the multipathway and environmental screening risk assessments conducted in support of RTR. Input uncertainty is concerned with how accurately the models have been configured and parameterized for the assessment at hand. For Tier 1 of the multipathway and environmental screening assessments, we configured the models to avoid underestimating exposure and risk. This was accomplished by selecting upper-end values from nationally representative datasets for the more influential parameters in the environmental model, including selection and spatial configuration of the area of interest, lake location and size, meteorology, surface water, soil characteristics, and structure of the aquatic food web. We also assume an ingestion exposure scenario and values for human exposure factors that represent reasonable maximum exposures. In Tier 2 of the multipathway and environmental screening assessments, we refine the model inputs to account for meteorological patterns in the vicinity of the facility versus using upper-end national values, and we identify the actual location of lakes near the facility rather than the default lake location that we apply in Tier 1. By refining the screening approach in Tier 2 to account for local geographical and meteorological data, we decrease the likelihood that concentrations in environmental media are overestimated, thereby increasing the usefulness of the screening assessment. In Tier 3 of the screening assessments, we refine the model inputs again to account for hour-by-hour plume rise and the height of the mixing layer. We can also use those hour-by-hour meteorological data in a TRIM.FaTE run using the screening configuration corresponding to the lake location. These refinements produce a more accurate estimate of chemical concentrations in the media of interest, thereby reducing the uncertainty with those estimates. The assumptions and the associated uncertainties regarding the selected ingestion exposure scenario are the same for all three tiers. For the environmental screening assessment for acid gases, we employ a single-tiered approach. We use the modeled air concentrations and compare those with ecological benchmarks. For all tiers of the multipathway and environmental screening assessments, our approach to addressing model input uncertainty is generally cautious. We choose model inputs from the upper end of the range of possible values for the influential parameters used in the models, and we assume that the exposed individual exhibits ingestion behavior that would lead to a high total exposure. This approach reduces the likelihood of not identifying high risks for adverse impacts. Despite the uncertainties, when individual pollutants or facilities do not exceed screening threshold emission rates ( i.e., screen out), we are confident that the potential for adverse multipathway impacts on human health is very low. On the other hand, when individual pollutants or facilities do exceed screening threshold emission rates, it does not mean that impacts are significant, only that we cannot rule out that possibility and that a refined assessment for the site might be necessary to obtain a more accurate risk characterization for the source category. The EPA evaluates the following HAP in the multipathway and/or environmental risk screening assessments, where applicable: Arsenic, cadmium, dioxins/furans, lead, mercury (both inorganic and methyl mercury), POM, HCl, and HF. These HAP represent pollutants that can cause adverse impacts either through direct exposure to HAP in the air or through exposure to HAP that are deposited from the air onto soils and surface waters and then through the environment into the food web. These HAP represent those HAP for which we can conduct a meaningful multipathway or environmental screening risk assessment. For other HAP not included in our screening assessments, the model has not been parameterized such that it can be used for that purpose. In some cases, depending on the HAP, we may not have appropriate multipathway models that allow us to predict the concentration of that pollutant. The EPA acknowledges that other HAP beyond these that we are evaluating may have the potential to cause adverse effects and, therefore, the EPA may evaluate other relevant HAP in the future, as modeling science and resources allow. IV. Analytical Results and Proposed Decisions A. What are the results of the risk assessment and analyses for the Boat Manufacturing source category? 1. Inhalation Risk Assessment Results Table 2 of this preamble provides an overall summary of the inhalation risk results. The results of the chronic baseline inhalation cancer risk assessment indicate that, based on estimates of current actual and allowable emissions, the MIR posed by the Boat Manufacturing source category was estimated to be 0.2-in-1 million and 0.3-in-1 million, respectively, from HAP being emitted from the open molding (resin/gelcoat) manufacturing process. The total estimated cancer incidence from the Boat Manufacturing source category based on actual emission levels is 0.00001 excess cancer cases per year, or one case in every 100,000 years. The total estimated cancer incidence from boat manufacturing industry emission sources based on allowable emission levels is 0.00002 excess cancer cases per year, or one case in every 50,000 years. Emissions of nickel compounds, ethyl benzene, and tetrachloroethene contributed 95 percent to this cancer incidence. Based upon actual or allowable emissions, no people were e [Text truncated at 120,000 characters. The full text is on the page linked above.] --- Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A2019-09583. Public record. Not legal advice.