Summary of Public Comments and Responses for Risk and Technology Review for Surface Coating of Large Appliances; Printing, Coating, and Dyeing of Fabrics and Other Textiles; and Surface Coating of Metal Furniture

December 2018

Summary of Public Comments and Responses for Risk and Technology Review for Surface Coating of Large Appliances; Printing, Coating, and Dyeing of Fabrics and Other Textiles; and Surface Coating of Metal Furniture

                     U. S. Environmental Protection Agency
                 Office of Air Quality Planning and Standards
                Sector Policies and Programs Division (D243-02)
                 Research Triangle Park, North Carolina 27711

The primary contacts regarding questions or comments on this document are:

Surface Coating of Large Appliances:
Kim Teal<PHONE_NUMBER><EMAIL_ADDRESS>Printing, Coating, and Dyeing of Fabrics and Other Textiles:
Paula Hirtz<PHONE_NUMBER><EMAIL_ADDRESS>Surface Coating of Metal Furniture:
Kaye Whitfield<PHONE_NUMBER><EMAIL_ADDRESS>U.S. Environmental Protection Agency
OAQPS/Sector Policies and Programs Division (D243-02)
Research Triangle Park, North Carolina 27711

                               TABLE OF CONTENTS

                                                                           Page
1.0	Introduction	1
2.0	List of Commenters	2
3.0	The Relationship Between the CAA Section 112(d)(6) Technology Review and the CAA Section 112(f) Risk Review	3
4.0	Risk Modeling and Determination	7
5.0	Regulation of Inorganic HAP	42
6.0	Technology Review for Large Appliances	44
7.0	High Efficiency Spray Equipment	44
8.0	Technology Review for Fabric Coating	45
9.0	Startup, Shutdown, Malfunction (SSM) Provisions	46
10.0	Malfunction Provisions for Fabric Coating	46
11.0	Electronic Reporting Provisions	48
12.0	Compliance Demonstrations after Operational Changes	54
13.0	EPA HAP List	55
14.0	Allowable and Acute Multiplier for Metal Furniture	55

List of Acronyms and Abbreviations

AEGL	Acute Exposure Guideline Levels
AERMOD	American Meteorological Society/EPA Regulatory Model
ATSDR	Agency for Toxic Substances and Disease Registry
CAA	Clean Air Act
CalEPA	California Environmental Protection Agency
CD	Central Data Exchange
CEDRI	Compliance and Emissions Data Reporting Interface
CFR	Code of Federal Regulations
CFR	Code of Federal Register
DNA	deoxyribonucleic acid
EPA	U. S. Environmental Protection Agency
ERPG	Emergency Response Planning Guidelines
FQPA	Food Quality Protection Act
FR	Federal Register
HAP	Hazardous Air Pollutant
HEM	Human Exposure Model
HON	Hazardous Organic NESHAP
HQ	hazard quotient
IRIS	Integrated Risk Information System
MACT	Maximum Achievable Control Technology
mg/m[3]	milligrams per cubic meter
MIR	Maximum Individual Risk
ug/m[3] 	micrograms per cubic meter
MOD 	mode of action
NAS	National Academy of Sciences
NEI 	National Emissions Inventory
NESHAP	National Emission Standards for Hazardous Air Pollutants
NRC	National Research Council
OAQPS	Office of Air Quality Planning and Standards
OEHHA	California's Office of Environmental Health Hazard Assessment
OMB	Office of Management and Budget
PB-HAP	persistent and bioaccumulative HAP
REL	CalEPA Reference Exposure Level
RfC	Reference Concentration
RfD	Reference Dose
RTR	Residual Risk and Technology Review
SAB	Science Advisory Board
SCC	Source Category Code
SSM	startup, shutdown, and malfunction
TOSHI	Target Organ-Specific Hazard Index
UF	Uncertainty Factor
U.S.C.	United States Code

Introduction
On September 12, 2018, the Environmental Protection Agency (EPA) proposed revisions to the National Emission Standards for Hazardous Air Pollutants (NESHAP) for three source categories in a single Federal Register (FR) notice:
Surface Coating of Large Appliances (40 Code of Federal Register (CFR) part 63, subpart NNNN);
Printing, Coating, and Dyeing of Fabrics and Other Textiles (40 CFR part 63, subpart OOOO); and
Surface Coating of Metal Furniture (40 CFR part 63, subpart RRRR).
Some significant comments and responses appear in the single preamble to the action for all three final rules. This document contains summaries of all the public comments that the EPA received on the proposed standards (comments that are summarized and addressed in the preamble to the proposed rule are also summarized in this document for completeness). Copies of all comments submitted are available at the EPA docket Center Public Reading Room. Comment letters are also available electronically through http://www.regulations.gov by searching for the following dockets:
Docket ID No. EPA-HQ-OAR-2017-0668 for subpart OOOO;
Docket ID No. EPA-HQ-OAR-2017-0669 for subpart RRRR; and
Docket ID No. EPA-HQ-OAR-2017-0670 for subpart NNNN.
Comments were submitted from the same five commenters to all three dockets, and each commenter submitted the same letter to all three dockets, so a single document is being prepared to summarize and respond to the comments for all three subparts.

List of Commenters
The EPA received five comment letters after September 12, 2018 on the proposed revisions to the NESHAP for the proposed residual risk and technology reviews (RTRs) and proposed amendments. All comment letters are contained in Docket ID No. EPA-HQ-OAR-2017-0668, Docket ID No. EPA-HQ-OAR-2017-0669, and Docket ID No. EPA-HQ-OAR-2017-0670. The commenter, affiliation, and item number in Docket ID No. EPA-HQ-OAR-2017-0668 are listed in Table 2-1. The comment letters are identified by their entry in Docket ID No. EPA-HQ-OAR-2017-0668 for convenience.
Table 2-1. Public Comments Received after the RTRs for Surface Coating of Large Appliances; Printing, Coating, and Dyeing of Fabrics and Other Textiles; and Surface Coating of Metal Furniture

Commenter Identification Code
Commenter and Affiliation
EPA-HQ-OAR-2017-0668-0116
David Darling, Vice President, Health, Safety and Environmental Affairs, American Coatings Association
EPA-HQ-OAR-2017-0668-0117 (letter) and -0118 (attachments)
Earth Justice on behalf of Blue Ridge Environmental Defense League, California Communities Against Toxics, Clean Wisconsin, and Sierra Club
EPA-HQ-OAR-2017-0668-0119
Matthew Todd, Chair, Residual Risk Coalition
EPA-HQ-OAR-2017-0668-0120
Shannon S. Broome, Executive Director, et al., The Air Permitting Forum
EPA-HQ-OAR-2017-0668-0121
Michael Abraczinskas, Director, Division of Air Quality, North Carolina Department of Environmental Quality

The Relationship Between the CAA Section 112(d)(6) Technology Review and the CAA Section 112(f) Risk Review
Comment: One commenter (0668-0117) argued that the EPA cannot use a finding of ample margin of safety in the risk assessment required by the Clean Air Act (CAA) section 112(f)(2) as a basis for not completing a technology review under CAA section 112(d)(6) or adopting more stringent standards based on the findings of that review. The commenter argues that the factors to be considered under CAA section 112(d)(6) are clearly technology and emission-based factors, and not health risks. The commenter argued that Congress intended to ensure that limits on toxic pollution are not frozen at the levels achievable by technologies or practices the first time standards were set, and that subsequently become outdated, and that this obligation is in addition to and independent from CAA section 112(f)(2). The commenter also noted that the EPA has recognized that CAA section 112(d)(6) is a continuation of the technology-based section CAA section 112(d) standard setting process, and serves the same goals of CAA section 112(d) overall to assure emission reductions.
The commenter (0668-0117) also argued that EPA must update standards to satisfy 112(d) for reasons other than developments in technology, such as when it is shown by legal precedent that the standards do not comply with the requirements of CAA section 112. The commenters cited several examples of when the EPA has revised standards to set limits for previously unregulated pollutants, unregulated emission points, and corrected other problems. The commenter argued that CAA section 112(d)(6) requires the EPA to make these corrections as part of these technology reviews.
The commenter argued that EPA may not use health risk information to avoid revising standards if otherwise required under CAA section 112(d)(6) because this section does not allow risk-based decision making. The commenter argued that the court record shows consistently that the standards established under CAA section 112(d) are to be technology based, and that EPA must account for technology developments that can achieve greater pollution reductions than when the EPA first set CAA section 112 emission standards.
The commenter (0668-0117) argued that the CAA's structure does not allow EPA to replace CAA section 112(d)(6) technology reviews with risk-based decision making because the CAA directs EPA to complete different CAA section 112(f)(2) and CAA section 112(d)(6) review and rulemaking obligations, without subjugating either one to the other. The commenter noted that the D.C. Circuit explained that these are "two distinct, parallel analyses: a recurring `technology review' under section 112(d)(6) and a one-time `risk review' under section 112(f)(2)." NASF v. EPA, 795 F.3d at 5 (explaining that "separately" from the technology review, in the risk review, "EPA addresses . . . lingering public health risk that the initial standard did not eliminate").
These are separate and independent requirements, as shown by the plain text of the statute, according to the commenter. The commenter notes that because Congress instructed EPA to conduct a separate health-risk based rulemaking in CAA section 112(f)(2), it is evidence that EPA is not to consider this factor under CAA section 112(d)(6), or Congress would have included this also under CAA section 112(d)(6). The commenter also noted that the D.C. Circuit has held that considering risk considerations into technology-based standard-setting under CAA section 112(d) "would collapse the technology-based/risk-based distinction at the heart of the Act, undermining the central purpose of the 1990 Amendments  -  to facilitate the near-term implementation of emission standards through technology-based solutions." Sierra Club, 353 F.3d at 990.
The commenter (0668-0117) also noted that the D.C. Circuit found that the EPA may not create a low risk subcategory that would be exempt from the CAA section 112(d)(6) requirement to establish technology-based standards, and that similar reasoning would mean that EPA cannot also create a risk-based exemption from the CAA section 112(d)(6) technology based review.
The commenter (0668-0117) argued that the ambiguity that EPA would need to rely on to consider risk in making decisions under CAA section 112(d)(6) does not exist when other paragraphs in CAA section 112 are considered. The commenter noted that EPA has earlier stated that CAA section 112(d)(6) is a continuation of the technology-based standard setting process established in CAA section 112(d)(2) and (3), and thus it can only be considered in a way that is consistent with CAA section 112(d)(2) and (3).
The commenter (0668-0117) also noted that the D.C. Circuit has held that the consideration of "non-air quality health and environmental impacts" can only be considered in determining whether or not to further strengthen the standards to promulgate an updated "beyond-the-floor" standard under CAA section 112(d)(2) and that the EPA has long interpreted these impacts to mean "the by-products of the control technology," and not the full impacts of the emissions.
The commenter (0668-0117) argued that the EPA's attempt to avoid amending the rules to account for technology based developments found during the review under CAA section 112(d)(6) based on risk is arbitrary and capricious because it appears, based on the e-mail record in the docket, to have resulted from a request from the Office of Management and Budget (OMB), and not from the EPA's own analysis. The commenter noted that other documents in the docket support EPA's previous interpretation that decisions related to CAA section 112(d)(6) are to be technology-based. The commenter argued that a change by the EPA in its own interpretation of CAA section 112(d)(6) would require EPA to propose and take public comment on the reasoned explanation for that change. The commenter also argued that because the change in interpretation was initiated by OMB and not by the EPA, the courts would offer no judicial deference under Chevron because OMB is not the agency with delegated statutory authority under the CAA.
The commenter (0668-0117) argued that, even if CAA section 112(d)(6) allowed EPA to consider risk, the EPA has failed to use the most current science in the residual risk assessment, and the findings of the EPA's risk assessment still show too much risk to justify avoiding the CAA section 112(d)(6) rulemaking based on the EPA's risk analysis.
Response: The EPA is not taking final action on the proposed interpretation discussed in this comment. Instead, the EPA has determined for the reasons described in the preamble to the final rule not to implement the proposed amendments to 40 CFR part 63, subparts NNNN, OOOO, or RRRR based on our technology review. As we are not relying on the proposed interpretation in our final action, we are not addressing the comments we received regarding the relationship between the technology review conducted under CAA section 112(d)(6) and the risk analysis under CAA section 112(f)(2). We note that the comment characterizes case law and EPA's interpretations of the CAA on issues that are not relevant to the final rules at issue. The EPA does not agree with those interpretations to the extent they are inconsistent with the EPA's interpretation of the statute, case law or prior actions.
Comment: Two commenters (0668-0119, 0668-0120) argued that the EPA has the discretion to consider potential for further risk reduction in determining whether a revision under CAA section 112(d)(6) is necessary.
Two commenters (0668-0119, 0668-0120) argued that to engage in reasoned decision making as required by Motor Vehicle Mfrs. Assn. of United States, Inc. v. State Farm Mut. Automobile Ins. Co., 463 U.S. 29, 43 (1983), EPA must consider all important aspects of the problem, and in a source category that satisfies ample margin of safety under Section 112(f), it would be unreasonable for EPA not to consider the degree of remaining risk posed and the potential for further risk reductions in determining whether revising the standard pursuant to CAA section 112(d)(6) is necessary.
Two commenters (0668-0119, 0668-0120) argued that the decision in Association of Battery Recyclers v. EPA, 716 F.3d 667 (D.C. Cir. 2013) does not compel a contrary result, in which the D.C. Circuit stated:
      Although petitioners contend that EPA failed to consider public health objectives or other controls imposed on emissions sources in determining whether more stringent standards were "necessary," nothing in section 112(d)(6)'s text suggests that EPA must consider such factors. To the contrary, the statute directs EPA to "tak[e] into account developments in practices, processes, and control technologies," 42 United States Code (U.S.C.) § 7412(d)(6), not public health objectives or risk reduction achieved by additional controls.
Id. at 672.
The commenters (0688-0119, 0668-0120) argued that this statement stands for the proposition that EPA was not compelled in that case to consider risk reduction and public health objectives in its necessity determination, but it does not prohibit EPA from considering the fact that a source category is low risk in making an "as necessary" determination, and it does not mean that EPA can ignore that fact in making its determination.
The second commenter (0668-0120) argued that CAA section 112(d)(6) directs EPA to "review and revise as necessary (taking into account developments in practices, processes, and control technologies), emission standards promulgated under this section no less often than every 8 years." 42 U.S.C. § 7412(d)(6) (emphasis added by the commenter). The commenter argued that while the D.C. Circuit may have said EPA is not compelled to consider "public health objectives" or "other controls," the EPA plainly has the discretion and should consider the risk reduction potential of additional controls recognizing that this information may be central to a determination of necessity.
The second commenter (0668-0120) argued that any source category that reduces lifetime risk to the maximum exposed individual in the source category to less than 1-in-1 million should be released from any future CAA section 112(d)(6) review. The commenter argued that CAA section 112(f)(2)(B) expressly preserves the EPA's use of the two-step decision process developed in the 1989 Benzene NESHAP. The commenter noted that in Benzene NESHAP, EPA stated an overall objective of "protecting the greatest number of persons possible to an individual lifetime risk level of no higher than approximately 1-in-1 million." (54CFR38044-45, September 14, 1989)
The second commenter (0668-0120) also noted that CAA section 112(c)(9) provides EPA with the authority to delist a source category from the CAA section 112(c) source category list if EPA makes a determination that "no source in the category (or group of sources in the case of area sources) emits such hazardous air pollutants (HAPs) in quantities which may cause a lifetime risk of cancer greater than one in one million to the individual in the population who is most exposed to emissions of such pollutants from the source." 42 U.S.C. section 7412(c)(9).
The second commenter (0668-0120) stated that based on these two factors, the EPA should make a determination that additional technology reviews are not needed under CAA section 112(d)(6) if the lifetime risks to the maximum exposed individual have been reduced to less than one in a million because the goals of the residual risk program have been achieved and further controls are likely to yield such small incremental reductions in risk as to make any further CAA section 112(d)(6) reviews and revisions unnecessary.
The second commenter (0668-0120) also argued that in light of precedent from the Supreme Court, the EPA should consider whether an existing NESHAP protects public health with an ample margin of safety in determining whether a revision under CAA section 112(d)(6) is "necessary." The commenter argued that whether the current standard protects the public health with an ample margin of safety should be considered as part of the necessity evaluation for revisions under CAA section 112(d)(6).
The two commenters (0688-0119, 0668-0120) also argued that the reading of the statutory language and the D.C. Circuit decision in Association of Battery Recyclers must be informed by Michigan v. EPA, 135 S. Ct. 2699 (2015), in which the Supreme Court was interpreting the language in Section 112(n) regarding whether it is "appropriate and necessary" to regulate utilities under Section 112, and in which Justice Scalia explained:
      Congress instructed EPA to add power plants to the program if (but only if) the Agency finds regulation "appropriate and necessary." § 7412(n)(1)(A). One does not need to open up a dictionary in order to realize the capaciousness of this phrase.
135 S. Ct. at 2707.
The second commenter (0668-0120) argued that although the Supreme Court focused on the term "appropriate" as "the classic broad and all-encompassing term that naturally and traditionally includes consideration of all the relevant factors"' (Id. (quoting White Stallion Energy Center, LLC v. EPA, 748 F.3d 1222, 1266 (Kavanaugh, J. concurring in part and dissenting in part), the use of the word "necessary" also imposes on EPA an obligation to make a determination regarding whether advances warrant a revision and the Michigan decision highlights that flexibility but does not permit EPA to "entirely fai[l] to consider an important aspect of the problem...." Id. (quoting State Farm, 463 U.S. at 43).
The first commenter (0668-0119) argued that EPA needs to consider not only what the cost of revising the standards to reflect a new development in technology would be, but also whether that expenditure would be "wasteful" in light of the risk reduction already achieved through implementation of CAA section 112(d)(3) and 112(f). See id. at 2707-2708.
The second commenter (0668-0120) argued that EPA has recognized that the "ultimate goal" of CAA section 112(d) and (f) emissions standards is protecting public health with an ample margin of safety. 71 FR 76,603, 76,609 (Dec. 21, 2006) (Hazardous Organic NESHAP (HON)). The commenter argued that once EPA establishes residual risk standards, it is within EPA's discretion to find further revisions under CAA section 112(d)(6) are not needed due to the efficacy of the existing CAA section 112(f) standards.
The two commenters (0668-019, 0668-0120) argued that as a general matter, the EPA should avoid making a technology-based change simply because the technology exists and appears cost effective, when making the existing NESHAP more stringent would not provide meaningful public health benefits when an ample margin of safety has been demonstrated.
The second commenter (0668-0120) concluded that the EPA should not finalize the proposal to require high efficiency spray guns because of the low risks presented by the large appliances and metal furniture source categories, and because these requirements would not reduce risk and would impose costs that may be difficult for companies to bear and remain competitive, given the investments already made to comply with the current standards.
Response: The EPA is not taking final action on the proposed interpretation discussed in this comment. Instead, the EPA has determined for the reasons described in the preamble to the final rule not to finalize amendments to 40 CFR part 63, subparts NNNN, OOOO, or RRRR based on our technology review. As we are not relying on the proposed interpretation in our final action, we are not addressing the comments we received regarding the relationship between the technology review conducted under CAA section 112(d)(6) and the risk analysis under CAA section 112(f)(2). We note that the comments characterize case law and the EPA's interpretations of the CAA on issues that are not relevant to the final rules at issue. The EPA does not agree with those interpretations to the extent they are inconsistent with the EPA's interpretation of the statute, case law or prior actions.
Risk Modeling and Determination
Comment: One commenter (0668-0117) stated that EPA must assess the health risk from malfunctions. The commenter stated that EPA has information available on major sources' malfunction and violation history that may be used with statistical methods and probability factors to assess health risk.
Response: We disagree with the commenter that emissions events in violation of the standards, whether or not they are caused by malfunction events, should be considered as part of the risk analysis. The EPA interprets CAA section 112 as not requiring emissions that occur during periods of malfunction to be factored into development of CAA section 112 standards and this reading has been upheld as reasonable by the Court in U.S. Sugar Corp. v. EPA, 830 F.3d 579, 606 - 610 (D. C. Cir. 2016). Moreover, the purpose of the risk review is to evaluate whether the emission limits -- the "standards promulgated pursuant to subsection (d)," not the non-compliance with those standards [CAA section 112(f)(2)(A)] -- should be made more stringent to reduce the risk posed after compliance with the underlying maximum achievable control technology (MACT) standard. To the extent that a source is violating the underlying MACT standard, no tightening of the emission standard under the residual risk review will avoid or mitigate against such violations. In other words, a source that is violating the MACT emissions standard promulgated under CAA section 112(d) would not be any more likely to be able to avoid such violations and comply with a different, presumably more stringent, standard promulgated under CAA section 112(f). These events are violations and subject to enforcement by the EPA, the states or citizens, and an action for injunctive relief is the most effective means to address such violations, whether or not they are caused by malfunctions, if an emissions event poses a significant health or environmental risk.
Comment:  One commenter (0668-0117) contended that the EPA's risk analysis significantly underestimates emissions because the risk analysis is based on an emission inventory that is largely calculated from emission factors and engineering judgment emission factors, which: (1) incorporate the erroneous assumption that equipment is operating as designed under normal conditions, and (2) do not account for environmental variables that significantly impact emissions (e.g., wind speed, which can have a substantial impact on emissions from certain sources).
The commenter stated that it is well-documented that emission factors underestimate emissions for a variety of reasons including inherent bias in the factors themselves and the inability to account for equipment malfunctions and environmental conditions. The commenter argued that the agency must adjust the emissions inventory using these same conclusions from the technology review and the large body of scientific evidence, which show that emissions factors underestimate emissions, in order to ensure that the inventory better represents reality and reflects actual emissions. The commenter provided the example of the EPA's Office of the Inspector General, which has stated that "[t]he heavy use of emission factors in the [national emissions inventory] makes the reliability of the data highly uncertain. Emission factors can result in emissions data of questionable reliability...."
The commenter stated that the tests used to develop emission factors are intentionally conducted on new equipment operating under normal conditions because emission factors are formulas that attempt to estimate long-term average emissions, quoting an EPA document: "[s]ources often are tested more frequently when they are new and when they are believed to be operating properly, and either situation may bias the results." The commenter further pointed out that the EPA itself notes that "[p]arameters that can cause short-term fluctuations in emissions are generally avoided in testing and not taken into account in test evaluation."
The commenter stated that the emissions from startup, shutdown, and malfunction (SSM) events can be significant, as EPA has acknowledged, and because emission factors incorporate the assumption that equipment is functioning as designed under normal conditions, emissions produced during SSM events are not accurately represented in reported emissions, which does not account for: (1) the emissions that are generated during upset and SSM events, nor the increased emissions that result from poor maintenance of equipment are accounted for in a facility's reported emissions and emissions inventories; nor (2) the increased emissions that result from poor maintenance of equipment. The commenter argued that, in this way, the EPA has failed to account for the significant emissions produced during SSM upset events or increased emissions that result from poor equipment maintenance, which results in grossly inaccurate, unreliable, and biased emissions data for these sources.
Response: The EPA disagrees with the commenter that the HAP emission inventories used in the risk analyses underestimate emissions because the inventories were not based on emission factors and engineering judgement as the commenter suggest. Instead the NESHAPs require the estimation of organic HAP emissions from surface coating operations by using mass balance methods. In the mass balance method, the reporter assumes that all organic HAP contained as solvents in the coatings evaporate and are emitted to the atmosphere unless the facility is using an add-on control device. If a facility is using an add-on control device, the facility is required to measure the organic HAP destruction efficiency of the device and apply that to the uncontrolled emissions to estimate emissions as part of the compliance demonstration process. The facility is then required to monitor the device and comply with operating limits to ensure it maintains the same efficiency as during the performance test.
These mass balance methods of estimating HAP emissions are not influenced by meteorology and are not influenced by the age of the equipment because they are based simply on the amount of HAP solvent consumed in the coatings. If different amounts of solvent were used, for example, to adjust coating viscosity to account for different coating application and drying conditions, then this would still be reflected in the mass balance calculations.
We also disagree with the commenter's assertions regarding emissions during SSM events as they apply to the emission inventories for these source categories. Because these inventories are based on mass balance accounting of the organic HAP consumed as solvents, those consumption data should include any excess HAP that were consumed as a result of a malfunction event. However, as we discussed in the preamble to the proposed rule (83 FR 46285), emissions are not likely to increase during malfunction events for these source categories because a malfunction would not, for example, increase the HAP content of the coatings being applied. In the event of a control device malfunction, a facility would see a deviation from the operating limits and would be required to take corrective action to minimize emissions which may include ceasing the coating operation until the control device can be repaired to normal operation.
Because the emission inventories used for the risk analysis for these surface coating categories are not based on emission factors and engineering judgement, the comments regarding whether the development of emission factors is based on representative data are not relevant to these source categories.
Comment: One commenter (0668-0117) stated that the EPA must assess the health risk from malfunctions because if EPA has knowledge that a certain amount of excess pollution per year routinely escapes facilities despite existing requirements, it must determine how these reasonably foreseeable "upset emissions" impact public health. The commenter also stated that the EPA must consider whether changes in the existing standards could mitigate the problem and better protect the public with an ample margin of safety, stating that it is not enough simply to point to the availability of enforcement suits by citizens or government entities.
Response: We disagree with the commenter that emissions events in violation of the standards, whether or not they are caused by malfunction events, should be considered as part of risk analyses. The EPA interprets CAA section 112 as not requiring emissions that occur during periods of malfunction to be factored into development of CAA section 112 standards and this reading has been upheld as reasonable by the Court in U.S. Sugar Corp. v. EPA, 830 F.3d 579, 606 - 610 (D. C. Cir. 2016). Moreover, the purpose of the risk review is to evaluate whether the emission limits -- the "standards promulgated pursuant to subsection (d)," not the non-compliance with those standards [CAA section 112(f)(2)(A)] -- should be made more stringent to reduce the risk posed after compliance with the underlying MACT standard. To the extent that a source is violating the underlying MACT standard, no tightening of the emission standard under the residual risk review will avoid or mitigate against such violations. In other words, a source that is violating the MACT emissions standard promulgated under CAA section 112(d) would not be any more likely to be able to avoid such violations and comply with a different, presumably more stringent, standard promulgated under CAA section 112(f). These events are violations and subject to enforcement by the EPA, the states or citizens, and an action for injunctive relief is the most effective means to address such violations, whether or not they are caused by malfunctions if an emissions event poses a significant health or environmental risk.
Comment: One commenter (0668-0117) argued that the EPA's analysis of all risks ignores the additional risk from short-term emission spikes associated with upsets because, for acute risk, the EPA used a low default emission adjustment factors of 1.2, 1.7, or 1.8 for the three source categories. The commenter argued that these values are low and that the EPA's own analyses show that EPA continues to ignore all emissions that occur through upsets, underestimating maximum short-term emissions and risk. In particular, as the Palma-Smith analysis states, EPA engaged in "data filtering," such that: "Accidental releases were dropped."[47] The commenter continued that the dropping of  "[a]ccidental releases" removes most of the maximum short-term emissions numbers that EPA must consider if it indeed wishes to fulfill the Act's requirement and its own interpretation of its responsibility. The commenter also stated that EPA gives no explanation for ignoring "[a]ccidental releases," and it could give no lawful or rational basis for ignoring these emissions.
Response: The EPA disagrees with the commenter that the acute risk multipliers are too low and notes that the commenter has not provided any data or rationale to support using higher multipliers, and has not commented on the EPA's methodology or data used in these rulemakings to develop the multipliers. The EPA did not use the Palma-Smith analysis to estimate acute emissions multipliers for the source categories in this action. The EPA believes that the multipliers chosen are accurate for these source categories. Each of these source categories perform surface coating generally using continuous processes. In two of the source categories (Large Appliances and Metal Furniture), add-on controls are only rarely used to maintain compliance with the NESHAP, so emissions are not likely to be affected by the malfunction of a control device. In the Printing, Coating, and Dyeing of Fabrics and Other Textiles source category compliant materials or add-on controls are used in the fabric coating processes. For those processes using compliant materials, a control device is not needed. However, for fabric coating processes employing the use of control devices, in the event of a control device malfunction, the coating application processes can be quickly stopped (e.g., the coating heads can be retracted from the web substrate and no additional coating applied) and excess emissions would be minimized. This is different from other industries (e.g., chemical manufacturing processes, primary and secondary smelting processes, petroleum refining processes) which may take more time to completely shut down a process and cease air emissions. In conclusion, the EPA is unaware of any upset or malfunction situation that would cause a significant increase in HAP emissions, due to the use of compliant materials by the three source categories, the continuous versus batch nature of the coating application process for each of the three source categories, and the immediate need to correct a malfunction to preserve the quality of the products produced by these three source categories. Therefore, the EPA believes that the factors used in the acute health risk analysis were appropriate for each of the source categories.
Comment: One commenter (0668-0117) argued that, under its own interpretation of § 7412(f)(2), the EPA must assess and reduce any remaining `residual' risk according to CAA § 112(f). 83 FR at 46,266. The commenter stated that it is necessary to assess "allowable" emissions because they reflect the maximum level facilities could emit without violating national emission standards, and doing so is consistent with the Science Advisory Board's (SAB's) recommendations. The commenter argued that post-idling startup emissions "remain" under EPA's existing standards, and are part of the "allowable" emissions because sources may produce them without violating the standards and therefore EPA cannot ignore them. The commenter argued that the EPA's risk assessments currently ignore these risks completely, treating them as zero, when in fact they may well push the cancer risk higher, potentially above EPA's benchmark of 100-in-1 million, or may well make the most-exposed person face a high chronic or other risk during and as a result of a malfunction.
The commenter stated that malfunction, upset, or "accidental" events increase emissions and thereby pose increased health risks that EPA must consider. The commenter further stated that although EPA has used the term "accidental," many such emission spikes occur as a result of events that can be prevented, disagreeing that they are actually "accidental." The commenter contended that where control equipment fails for any reason, emissions could be at least 100 times greater than usual (e.g., in the circumstance where a control device has 99% efficiency, such that an uncontrolled release would cause 100 times the usual amount of emissions), and that ignoring such emissions is an unlawful and arbitrary example of the problem of ignoring health risk in the agency's assessment. The commenter stated that the higher emissions caused by malfunction or upset emissions can accumulate and combine to increase public health impacts and lead to much higher risks for community members than those they face on a daily basis.
The commenter stated that failing to look at the true potential for spikes in emissions over a person's lifetime may underestimate acute risk, cancer risk and the amount of chronic non-cancer risk based on pollutants that persist in the environment, such as nickel and antimony (for the two source categories EPA recognizes emit one or both of those pollutants). The commenter argued that ignoring these emission spikes is equivalent to treating additional health risk caused by exceedances as zero. The commenter pointed out that SAB has criticized EPA's underestimation of maximum short-term emissions, and that this rulemaking continues to suffer from the same flaws that SAB identified. The commenter opined that the EPA knows that there is additional risk from malfunctions and violations, and it has no lawful or scientific basis to ignore this additional risk.
In referring to EPA's method of calculating acute risk, which the commenter stated that EPA considers a "worst-case" scenario approach, the commenter argued that this method does not attempt to account for some variability in assessing health risks as shown by the use of a factor and does not come close to modeling the actual "worst case" scenario because each such factor is too low, as it ignores malfunctions that exceed the standards. The commenter further opined that EPA's recognition that it is appropriate to use factors to assess higher emissions shows that the agency could simply use a more accurate factor to account for malfunctions for acute and other types of health risk in order to close the gap and respond appropriately to SAB's criticism of its current method. The commenter pointed out that the EPA regularly uses statistical methods and probability factors, which are readily available tools that EPA can also use to assess health risk due to malfunctions in order to set clean air standards.
The commenter stated that, to create representative factors to assess the health risk from malfunctions, EPA has information available, or can collect information, on major sources' malfunction and violation histories from the reports required under the prior rule. The commenter further stated that, if EPA needs more refined data regarding these emissions to fulfill its legal obligation, EPA should simply request additional data from sources.
Response: Consistent with previous risk assessments, the EPA considered both allowable and actual emissions in assessing chronic inhalation exposure and risk under section 112(f)(2) for these source categories (see e.g., the National Emission Standards for Coke Oven Batteries (70 FR 19998-19999, April 15, 2005) and in the proposed and final National Emission Standard for Organic Hazardous Air Pollutants from the Synthetic Organic Chemical Manufacturing Industry, or HON (71 FR 34428, June 14, 2006, and 71 FR 76603, December 21, 2006)). We disagree with the commenter that emissions that exceed standards should be part of the risk analysis. We further disagree with the commenter that we have ignored the risk associated with malfunctions. The final rule is designed to require sources to comply during all periods of operation. As explained in the preamble to the proposed rule, it is not possible to model malfunctions in the risk assessment, because by nature they are infrequent and unpredictable. The main purpose of the risk reviews for these three source categories is to evaluate whether the emission limits  -  the "standards promulgated pursuant to subsection (d)" not the non-compliance with those standards  - should be made more stringent to reduce the risk posed after compliance with the underlying MACT standard. To the extent that a source is violating the underlying MACT standard, no tightening of the emission standard as a result of the residual risk review will avoid or mitigate such violations. In other words, a source that is violating the MACT emissions standard promulgated under section 112(d) would not be any more likely to be able to avoid such violations and comply with a different presumably more stringent standard promulgated under section 112(f). Such events are violations and subject to enforcement by the EPA, the States, or citizens, and an action for injunctive relief is the most effective means to address violations whether or not they are caused by malfunctions if an emissions event poses a significant health or environmental risk.
We also disagree with the commenter that the EPA's emissions inventory and risk analysis ignores post idling startup emissions and treats them as zero. As explained in other responses to the same commenter, the emission inventories for surface coating sources using compliant materials are based on mass balance methods in which all the organic HAP in coatings are assumed to be emitted. If a source is using an add-on control device, the emissions are still based on a mass balance, but also take into account the efficiency of the control device.
We disagree with the commenters assertion that emissions from these surface coating source categories to be higher during periods of startup. Nothing during the startup period for these source categories would indicate the emissions should be higher than at any other time because the HAP content of coatings should be the same at all times. If a facility is using an add-on control device, the control device must be complying with the operating limits established for that device (e.g., the thermal oxidizer temperature must be brought up to the minimum allowable operating temperature) before the facility can begin surface coating. In addition, all exemptions from the emission limits associated with periods of startup, shutdown and malfunction were removed from the NESHAP, and the emission limits now apply at all times. For these reasons, we are not revising our approach to evaluating risk in this final action.
Comment: One commenter (0668-0117) argued that, as part of the residual risk assessment for each source category, the EPA unlawfully and arbitrarily failed to assess the health risks for "the individual most exposed to emissions" from each of the three source categories, as § 7412(f)(2) requires. The commenter stated that the EPA has chosen an arbitrary point, a census-block centroid, without demonstrating that this is equivalent to the person "most placement of new receptors." The commenter expressed concern that the EPA's method is not scientific or lawful, would not be reproducible, and that application would vary should a different risk assessor conduct modeling on an individual facility. The commenter argued that the EPA must have verification metrics in place to ensure that it assesses health risks based on the actual or likely locations of specific receptors representative of those living near the facility and/or who are the people most exposed to a source or source category.
The commenter stated that taking geographic variation out of the equation fails to properly account for exposure to the "individual most exposed to emissions" as required by section 7412(f)(2)(A), and fails to provide an accurate accounting of risks. The commenter continued that estimating the annual average concentrations at the area-weighted centers of census blocks blatantly and artificially underestimates the risk estimated for people at the fence-line since the center of a census block is almost always further away from the facility than the fence-line. The commenter continued that census blocks vary greatly in size, especially outside of large urban areas, yet EPA provides no evidence that it reviewed census block size or configuration to consider how concentrations of pollutants might vary within these blocks. The commenter concluded that area-weighted centers of census blocks likely significantly underestimate exposure in some cases, and by failing to assess health risks for the most-exposed person (rather than just by the middle of a census block), the EPA violates this provision.
The commenter argued that the EPA's failure to adjust receptor points for residents living on the fence-line is particularly inexcusable given that the HEM-AERMOD model allows for such an adjustment, and that such an adjustment was appropriately made for the estimation of acute health risks. The commenter continued that having recognized that the maximum exposed individual for acute risks is likely present at the fence-line, EPA cannot justify failing to analyze cancer and other chronic health effects in a similar manner.
Response: The EPA disagrees with the comment. In a national-scale assessment of lifetime inhalation exposures and health risks from facilities in a source category, it is appropriate to identify exposure locations where it may be reasonably expected that an individual will spend a majority of his or her lifetime. In determining chronic risks, it is appropriate to use census block information on where people actually reside, rather than points at the property line, to locate the estimation of exposures and risks to individuals living near such facilities. Census blocks are the finest resolution available as part of the nationwide population data (as developed by the U.S. Census Bureau); on average, a census block is comprised of approximately 40 people and about 10 households. In the EPA risk assessments, the geographic centroid of each census block containing at least one person is used to represent the location where all the people in that census block live. The census block centroid with the highest estimated exposure then becomes the location of maximum exposure, and the entire population of that census block is assumed to experience the maximum individual risk (MIR). In some cases, because actual residence locations may be closer to or farther from facility emission points, this may result in an overestimate or underestimate of the actual annual concentrations (although there is no systematic bias for average levels). Given the relatively small dimensions of census block in densely-populated areas, there is little uncertainty introduced by using the census block centroids in lieu of actual residence locations. There is the potential for more uncertainty when the census blocks are larger, although there is still no systematic bias. The EPA concludes that the most appropriate locations at which to estimate chronic exposures and risks are the census block centroids because: 1) census blocks are the finest resolution available in the national census data; 2) facility fence-lines do not typically represent locations where chronic exposures are likely (i.e., people do not typically live at the fence-line of facilities); and 3) there is no bias introduced into the estimate of MIR by using census block centroid locations. In its peer review of the methodologies used to estimate risks as part of the RTR rulemaking efforts, the EPA's SAB endorsed this approach.
In addition to the approach described above, the EPA recognizes that where a census block centroid is located on industrial property or is large and the centroid is less likely to be representative of the block's residential locations, the block centroid may not be the appropriate surrogate. For these source categories (as described in Residual Risk Assessment for the Surface Coating of Large Appliances Source Category (Docket ID No. EPA - HQ - OAR - 2017 - 0670), Residual Risk Assessment for the Surface Coating of Metal Furniture Source Category (Docket ID No. EPA - HQ - OAR - 2017 -  0669), and Residual Risk Assessment for the Printing, Coating, and Dyeing of Fabrics and Other Textiles Source Category (Docket ID No. EPA - HQ - OAR - 2017 -  0668)), in cases where a census block centroid was within 300 meters of any emission source (and therefore possibly on facility property), we viewed aerial images of the facility to determine whether the block centroid was likely located on facility property. Likewise, we examined aerial images of all large census blocks within one kilometer of any emission source. If the block centroid did not represent the residential locations within that block, we relocated it to better represent them and/or we added receptors for residences nearer to the facility than the centroid. For these source categories, we added several receptors for census blocks where the centroid location was not representative of the residential locations. Appendix 7 of the risk assessment documents cited above provides additional information on these changes for each source category.
Thus, despite the commenter's assertions, the EPA's approach to identifying the most exposed individual is reasonable.
Comment: One commenter (0668-0117) contended that the EPA is legally required to assess the health risks to the "individual most exposed" to these sources' emissions. 42 U.S.C. § 7412(f)(2). The commenter stated that the EPA must account for the increased susceptibility of children and developing fetuses to HAP emissions from this source category in the risk assessment. The commenter is concerned that the EPA's failure to include an adequate evaluation of increased early life susceptibility to HAP emissions systematically underestimates risk from the Coatings source categories. The commenter stated that the EPA's failure to account for vulnerability and variability based on the current science, particularly the science addressing early-life and socioeconomic factors in the risk related to exposure, has led EPA to underestimate the health risks that these sources cause to the most-exposed individuals. The commenter referred to the National Academy of Sciences (NAS) report and other new scientific and policy developments, stating that it directs EPA to better account for vulnerability and variability. The commenter noted that the science is clear that "children are not `little adults'" when it comes to toxic chemicals, stating that they are susceptible to greater harm from exposure to toxic chemicals because they are still growing and developing, and they are exposed to such chemicals at a greater rate than adults because of age-specific behaviors and physiological characteristics.
The commenter (0668-0117) contended that EPA must also better account for other types of human variability because some people exposed to the same amount of a pollutant experience greater health risk due to other factors, such as genetics and baseline health status. The commenter stated that socioeconomic status has been shown to act as a proxy for other types of human variability to chemical risk that EPA has not adequately addressed in its draft risk assessments for this proposal. The commenter opined that EPA's demographic analysis acknowledges that disparities exist and shows the need for EPA to evaluate the impact of disproportionate exposure and health risks for certain demographic groups in the context of the risk assessment.
The commenter (0668-0117) argued that the EPA must:
Consistent with the Office of Environmental Health Hazard Assessment (OEHHA) Cancer Guidelines,[,] apply age-dependent adjustment factors for all carcinogens, not just known mutagens, to account for increased early life susceptibility and pre-natal adjustment factors for all carcinogens of at least a factor of 10X (similar to the 10X Age Specific Factor applied to the prenatal life stage by California EPA scientists), to account for pre-natal susceptibility and exposures. The commenter noted that NAS has recognized this as a "missing" default in EPA's approach that it should address. The commenter quoted NAS: "EPA needs methods for explicitly considering in cancer risk assessment ... chemicals that do not meet the threshold of evidence that the agency is considering for judging whether a chemical has a mutagenic mode of action (MOA) .... Special attention should be given to hormonally active compounds and genotoxic chemicals that do not meet the threshold of evidence requirements."
          For chronic non-cancer risk, apply child-specific reference values (such as those created by California EPA scientists), where available. Most of EPA's Integrated Risk Information System (IRIS) toxicity threshold values (reference concentrations (RfCs) and reference doses (RfDs)) used for chronic non-cancer risk assessment do not incorporate the latest science on increased susceptibility of children. The commenter noted that EPA, in its risk assessment, has recognized that compounds such as nickel and antimony are emitted, and the commenter stated that the EPA needs to account for early exposure and the greater risk to and susceptibility of children to such compounds.
          For chronic non-cancer risk, apply an additional default or uncertainty factor (UF) to account for early-life exposure (i.e., a children's default safety factor such as those created by California EPA scientists) of at least 10 (for non-cancer chronic & acute impacts), where specific information on children's vulnerability is unavailable (consistent with NAS recommendations, the science developed and considered by OEHHA, and the 10X factor enacted by Congress in the Food Quality Protection Act). The commenter opined that most of EPA's IRIS toxicity threshold values (RfCs and RfDs) used for chronic non-cancer risk assessment do not incorporate the latest science on increased susceptibility of children. The commenter noted that EPA, in its risk assessment, has recognized that compounds such as nickel and antimony are emitted, and the commenter stated that the EPA needs to account for early exposure and the greater risk to and susceptibility of children to such compounds.
The commenter (0668-0117) contended that, under § 7412(f)(2), it would be both unlawful for EPA to ignore the health risks that it knows that the 1000 tons per year of HAPs emitted by these source categories can cause and it would be arbitrary and capricious for EPA to avoid applying the best available science here. The commenter continued that it also would be unacceptable and unjust for EPA to ignore the current scientific and regulatory tools available for communities affected by toxic air pollution from the current source categories and many others. The commenter argued that, if EPA wishes to act on its stated commitment to environmental justice, it should finally start to use the science available now to address these impacts and risks, while also working to continue to update its risk assessment approaches.
The commenter (0668-0117) attached the health impact and risk documents cited in these comments as part of an accompanying Appendix, unless available to EPA for other rulemaking or in the EPA Office of Science Advisor docket on the Request for Information on Cumulative Risk Assessment, EPA-HQ-ORD-2013-0292. The commenter stated that these comments incorporate all of the previously submitted scientific documents on these issues by reference.
Response: We disagree with the commenter's claim that the risk assessment for this source category does not consider the groups that may be most at-risk (e.g., children and developing fetuses). See Response above for a discussion of EPA's approach to identifying the most exposed individuals. In addition, when the EPA derives exposure RFCs and unit risk estimates for HAPs, it also considers the most sensitive populations identified in the available literature, and importantly, these are the values used in our risk assessments. The EPA has an approach for selecting appropriate health benchmark values and, in general, this approach places greater weight on the EPA-derived health benchmarks than those from other agencies. Additionally, the approach of favoring EPA benchmarks (when they exist) has been endorsed by the SAB and ensures the use of values most consistent with well-established and scientifically-based EPA science policy. The EPA is continuing to evaluate the most appropriate use for the OEHHA's child-specific RfDs. We note that there are currently no such values for HAP inhalation; therefore, their current utility would be limited to persistent and bioaccumulative HAP (PB-HAP), which may be associated with non-negligible ingestion exposures. The evaluation of the appropriateness of these values in the context of the RTR Program and EPA science policy is necessary prior to using these child-specific RfDs.
With respect to exposure, we use a health-protective assumption of a 70-year exposure duration, in which populations are conservatively presumed to be exposed to airborne concentrations at their residence continuously, 24 hours per day for a full lifetime, including childhood.
With respect to cancer, the EPA uses the age-dependent adjustment factor approach referred to by the commenter, but limits the application of age-dependent adjustment factors to carcinogenic pollutants that are known to act via mutagenic MOA; in contrast, the OEHHA approach is to apply them across the board for all carcinogens, regardless of MOA. In lieu of chemical-specific data on which age or life-stage specific risk estimates or potencies can be determined, default age-dependent adjustment factors can be applied when assessing cancer risk for early-life exposures to chemicals which cause cancer through a mutagenic MOA. With regard to other carcinogenic pollutants for which early-life susceptibility data are lacking, it is the Agency's long-standing science policy position that use of the linear low-dose extrapolation approach (without further adjustment) provides adequate public health conservatism in the absence of chemical-specific data indicating differential early-life susceptibility or when the MOA is not mutagenicity. The basis for this methodology is provided in the 2005 Supplemental Guidance.
The EPA also disagrees with the commenter that a children's default safety factor of 10 or more should be added to EPA's reference values. In response to the 10X factor enacted by Congress in the Food Quality Protection Act (FQPA) (1996)[,] to the EPA non-cancer reference value derivation, the EPA evaluated their methods for considering children's risk in the development of reference values. As part of their response, the EPA (i.e., the Science Policy Council and Risk Assessment Forum) established the RfD/RfC Technical Panel to develop a strategy for implementing the FQPA and examine the issues relative to protecting children's health and application of the 10X safety factor. One of the outcomes of the Technical Panel's efforts was an in-depth review of a number of issues related to the RfD/RfC process (EPA 2002). The most critical aspect in the derivation of a reference value pertaining to the FQPA has to do with variation between individual humans and is accounted for by a default UF when no chemical-specific data are available. EPA reviewed the default UF for inter-human variability and found the EPA's default value of 10 adequate for all susceptible populations, including children and infants. The EPA also recommended the use of chemical-specific data in preference to default UFs when available (EPA, 1994, 2011), and is developing Agency guidance to facilitate consistency in the development and use of data-derived extrapolation factors for RfCs and RfDs (EPA, 2011).  Additionally, the EPA also applies a database UF which is intended to account for the potential for deriving an under protective RfD/RfC as a result of an incomplete characterization of the chemical's toxicity. In addition to the identification of toxicity information that is lacking, review of existing data may also suggest that a lower reference value might result if additional data were available.
In conclusion, the estimated risks must also be considered in the context of the full set of assumptions used for this risk assessment. Our unit risk estimates for HAP are considered a plausible upper-bound estimate with an appropriate age-dependent adjustment factor; actual potency is likely to be lower and some of which could be as low as zero. Our chronic noncancer reference values have been derived considering the potential susceptibility of different subgroups, with specific consideration of children. In addition, an extra 10X UF is not needed in the RfC/RfD methodology because the currently available factors are considered sufficient to account for uncertainties in the database from which the reference values are derived. After considering these and other factors, we continue to consider the risks from emissions after application of the revisions to the NESHAP for this source category to provide an ample margin of safety (consistent with the Benzene NESHAP framework).
Comment: One commenter (0668-0117) argued that the EPA is using outdated reference values for benzene and other emitted HAPs. The commenter provided a comparison of cancer potency values utilized by EPA and provided the cancer potency values recommended by California Environmental Protection Agency (CalEPA) based on the latest science (Table A), noting that although cancer potency values used by EPA are higher in some instances, an emissions-weighted analysis of the different potency values used by EPA versus those recommended by CalEPA shows that cancer risk may have been two times higher had EPA utilized up to date factors. In the commenter's opinion, EPA must use the latest reference values, as summarized by CalEPA in updated guidance in 2015.
   Table A: Comparison of Cancer Potency Factors Utilized by EPA vs. CalEPA
                                     HAPs:
    CalEPA Cancer Potency Unit Risk (1/microgram per cubic meter (ug/m[3]))
                   EPA Cancer Potency Unit Risk (1/ug/m[3])
                                 Percent Lower
                              Potency of EPA value
 1,3-
 butadiene
 0.00017
 0.00003
 82%
 Benzene
 0.000029
 7.8E-06
 73%

The commenter further argued that the EPA has used some out-of-date and less health-protective reference inhalation factors for chronic exposure to benzene and several other important high-exposure HAPs. The commenter provided a comparison of RfC values utilized by EPA and the RfC values recommended by CalEPA to assess chronic exposure based on the latest science (Table B), stating that although certain RfC values used by EPA are slightly lower (e.g., more health protective) in some instances, the higher, less protective RfC values remain in use for selecting HAPs that have a high exposure impact based on emissions and toxicity. In the commenter's opinion, EPA must use the latest reference values, as summarized by CalEPA in updated guidance in June 2015.
Table B: Comparison of Chronic Inhalation Reference Concentrations (RfC) Utilized by EPA vs. CalEPA
                                     HAPs:
                             Cal EPA RfC (ug/m[3])
                               EPA RfC (ug/m[3])
                        EPA RfC, Factor less protective
 Benzene
 3
 30
 10
 Toluene
 300
 5,000
 17
 Nickel
 0.014
 0.09
 6

Response: The EPA does not agree that its approach to evaluating risk is flawed as the commenter states. The EPA has a tiered prioritized list of appropriate chronic health benchmark values and, in general, this hierarchy places greater weight on the EPA-derived health benchmarks than those from other agencies. We have a prioritization process aimed at incorporating into our assessments the best available science with respect to dose-response information. This information is obtained from various sources and prioritized according to 1) conceptual consistency with the EPA risk assessment guidelines and 2) level of peer review received. Where we are lacking dose-response information with higher priority (e.g., IRIS), we use other information sources, such as the Agency for Toxic Substances and Disease Registry (ATSDR) and CalEPA. Notably, this priority list favoring the EPA benchmarks (when they exist) over all others has been endorsed by the SAB. "The Panel found the EPA's approach to selecting dose-response chronic toxicity values to be generally sound... The Panel supports the use of IRIS as the preferred database for chronic dose-response data. The Panel also strongly recommends that the EPA develop toxicity values for all HAP insofar as the data permit, and that it updates IRIS in a timelier manner." The preferred database for chronic dose-response data is and should be the IRIS database.
Comment: One commenter (0668-0117) contended that the acute reference value used to evaluate benzene exposure is two orders of magnitude too high, leading to a "very significant" underestimate of the acute non-cancer health hazards of benzene emissions. The commenter continued that the EPA used an acute reference exposure value of 1.3 milligrams per cubic meter (mg/m[3][)], while California EPA uses a value of 0.027 mg/m[3] based on the latest science. The commenter argued that, given that the EPA is evaluating this value, EPA recognizes CalEPA reference exposure levels (RELs) as authoritative, and regularly uses them in risk assessments. The commenter contended that the EPA must use this more up-to-date benzene value in its risk assessments and update the assessments accordingly.
The commenter noted that the D.C. Circuit recently held in reviewing an EPA risk assessment pursuant to § 7412(d)(4) that the EPA had not sufficiently justified refusing to use the most up-to-date OEHHA reference values. See, e.g., Sierra Club v. EPA, 895 F.3d 1, 11-12 (D.C. Cir. 2018). The commenter also noted that the EPA similarly has failed to justify its refusal to use such values for benzene, 1-3 butadiene, toluene, and nickel, here.
Response: After proposal, we stopped using California EPA's previous acute (1-hour) REL for benzene of 1.3 mg/m[3] since California EPA (CalEPA) no longer supports this value. CalEPA replaced this value with an updated acute REL of 0.027 mg/m[3]. However, based on an examination of CalEPA's new acute (1-hour) REL for benzene and taking into account aspects of the methodology used in the derivation of the value and how this assessment compares to the ATSDR toxicological assessment, we have decided not to use this new value to support EPA's risk and technology review rules. Therefore, we currently do not determine an acute REL for benzene. It should be noted that, even if we had used the new CalEPA acute REL for benzene in our risk assessment, the HQ would have been well below 1; 0.16 for the Printing, Coating, and Dyeing of Fabrics and Other Textiles source category and 0.01 for Large Appliance Coatings (Benzene was not emitted from the Metal Furniture Coatings source category). Those levels of risk are acceptable and provide an ample margin of safety as explained in the preamble to the proposed rule and the risk review documents.
Comment: One commenter (0668-0117) noted that for the three coatings source categories, it is unclear whether there are HAP missing from the EPA's risk assessment and that the EPA should confirm that it has assessed the health risk for all emitted HAP. The commenter stated that the EPA must assess health risk from all pollutants, even where it has no current reference value, or must use an UF to make up for the lack of a reference value. The commenter stated that in the absence of an available RfD, the EPA must, at minimum, add an UF to account for the additional risk that a HAP likely causes, until such time as the EPA does have a reference value to use. The commenter noted that the EPA stated that "an understatement of risk for these pollutants at estimated exposure levels is possible," due to the lack of reference values for a chemical and/or for a particular type of health risk.
The commenter (0668-0117) contended that the EPA may not lawfully or rationally treat risk as zero when the science shows risk is present, and that just because the EPA has not yet developed a reference value for a pollutant, type of exposure, or type of risk, does not mean risk does not exist and can be ignored. The commenter noted that the EPA's risk assessment acknowledges other HAP emissions for which it has no reference values, but stated that the EPA has failed to assess risk at all for these pollutants. The commenter added that the EPA states that it performed no risk assessment for some HAPs emitted by these source categories. The commenter expressed concern that the EPA appears to have failed to account in any way for the acute health risks posed by these HAP because of the lack of a reference values. The commenter stated that the EPA did not even carry out a qualitative assessment of these HAPs, in effect assuming that risk from the HAPs is zero, which is not justified. The commenter noted that the EPA recognizes that its approach creates a potential understatement of health risk, but the EPA has not adequately explained how it has attempted to remove that understatement.
The commenter (0668-0117) disagreed with the EPA's policy of looking at Acute Exposure Guideline Levels (AEGL) and Emergency Response Planning Guidelines (ERPG) values in the absence of reference values or RELs, because AEGL and ERPG values are designed only for emergency exposure response and cannot be considered health-protective for community members facing potentially repeat exposures over a lifetime to acute risks from emission spikes.
The commenter (0668-0117) contended that, under § 7412(f)(2), it is unlawful, arbitrary, and capricious for EPA not to assess risk at all from a HAP, because in failing to do so EPA is ignoring scientific evidence before the agency and ignoring the risks it well knows exists since these risks are what led Congress to list that pollutant under § 7412(b)(1). The commenter stated that, just as National Lime Association, 233 F.3d at 642, requires EPA to set emission limits for all HAPs, EPA must assess the health risk for all listed HAPs. The commenter contended that EPA may not, as it stated here, just write off the risks of HAPs emitted by these source categories that the CAA requires EPA to regulate. The commenter argued that, to meet the requirements of § 7412(f)(2) and follow the best available current science, if there is no reference value for a pollutant, EPA may not ignore health risks associated with these pollutants completely in its analysis.
The commenter (0668-0117) stated that it is also arbitrary and capricious for EPA to treat all health risks from these pollutants as zero or non-existent due to the lack of a reference value quantifying a specific risk. The commenter quoted NAS as stating that it is a problem that "agents that have not been examined sufficiently in epidemiologic or toxicologic studies are insufficiently included in or even excluded from risk assessments" by EPA.[62] The commenter continued that the NAS has made clear that it is not appropriate as a scientific matter to treat such compounds "as though they pose no risk that should be subject to regulation."[63] The commenter stated that the NAS has recommended that EPA develop "explicit defaults to use in place of missing defaults," including for its "untested-chemical assumption," i.e., that a chemical with no reference value poses no risk.[64]
The commenter (0668-0117) opined that EPA has recognized that many pollutants creating acute risks are pollutants for which it has no reference value, as shown by each of the draft Risk Assessment Tables 3.1-1, listing reference values for other kinds of health risks for some pollutants and many for which no acute health reference value or REL is included (blank or no REL listed, only an emergency value listed). The commenter stated that, for that reason, EPA looks at inappropriate values (i.e., the AEGLs and ERPGs), which are designed only for emergency exposure response and cannot be considered health-protective for community members facing potentially repeat exposures over a lifetime to acute risks from emission spikes.[60] The commenter contended that EPA is underestimating acute risks by using those values.
The commenter (0668-0117) also contended that the EPA provides no information regarding which HAPs for which it is not accounting for any health risk, or certain health risks, stating that this is a violation of notice-and-comment as well as a failure to assess and address the risks based on information it does have.
Response: The EPA does not agree with these comments and the EPA's SAB considered these issues in their May 10, 2010 response to the EPA Administrator (EPA-SAB-10-007). In that response, the SAB Panel recommended that, for HAP that do not have dose-response values from the EPA's list, the EPA should consider and utilize, as appropriate, additional sources for such values that have undergone adequate and rigorous scientific peer review. The SAB panel further recommended that the inclusion of additional sources of dose-response values into the EPA's list should be adequately documented in a transparent manner in any residual risk assessment case study. We agree with this approach and have considered other sources of dose-response data when conducting our risk determinations under RTR. However, in some instances no sources of information beyond those included in the EPA's list are available. For a tabular summary of HAPs that have dose response values for which an exposure assessment was conducted, refer to Table 3.1-1 of Residual Risk Assessment for the Surface Coating of Large Appliances Source Category (Docket ID No. EPA - HQ - OAR - 2017 - 0670), Residual Risk Assessment for the Surface Coating of Metal Furniture Source Category (Docket ID No. EPA - HQ - OAR - 2017 -  0669), and Residual Risk Assessment for the Printing, Coating, and Dyeing of Fabrics and Other Textiles Source Category (Docket ID No. EPA - HQ - OAR - 2017 - 0668).
The EPA agrees that we should ultimately develop toxicity values for all HAP utilizing all credible and relevant toxicity information. The need to update assessments with newly available data as well as the need to complete toxicological assessments for all HAP lacking dose-response assessments further increases the importance of Agency activities to streamline and fully utilize the EPA's already overloaded IRIS program. To that end, the EPA has always prioritized for future IRIS assessments those HAP without dose-response values but with the greatest potential for public exposure. As a result of this prioritization, while not all HAP have scientifically accepted dose-response values that can be used in residual risk assessments, it is clear that the vast majority of HAP that carry the potential to significantly impact the results of residual risk assessments do, in fact, have credible dose-response values. Thus, while we are not yet at the point where all HAP have dose-response values, we are generally capable of deriving reasonable risk estimates for those HAP that dominate the risks from any one source category. In the course of each residual risk assessment, should we encounter HAP without dose-response values which carry the potential to create significant risks, we clearly point those out as uncertainties and target them for future IRIS assessments. In general, we strive to strike a balance in our assessments, meaning that while some factors likely lead to underestimates of risk, others likely lead to overestimates of risk. We conclude that the risk assessment for these source categories are sufficient to support a decision on the acceptability of the risk and ample margin of safety.
The EPA does not rely exclusively upon AEGL values for assessment of acute exposures. Rather, the EPA's approach is to consider various acute health effect reference values, including the California REL, in assessing the potential for risks from acute exposures. To better characterize the potential health risks associated with estimated acute exposures to HAP, and in response to a key recommendation from the SAB's peer review of the EPA's RTR risk assessment methodologies, we generally examine a wider range of available acute health metrics (e.g., RELs, AEGLs) than we do for our chronic risk assessments. This is in response to the SAB's acknowledgement that there are generally more data gaps and inconsistencies in acute reference values than there are in chronic reference values. In some cases, when Reference Value Arrays for HAP have been developed, we consider additional acute values (i.e., occupational and international values) to provide a more complete risk characterization. As discussed in the preamble to the proposed rule, the exposure guidelines EPA considers depend on which exposure guidelines are available for the various HAP emitted. The EPA uses AEGL and ERPG values (when available) in conjunction with REL values (again, when available) to characterize potential acute health risks. However, it is often the case that HAP do not have all of these acute reference benchmark values. In these instances, the EPA can only describe the potential acute health risk in relation to the acute health values that are available. Importantly, when interpreting the results, we are careful to identify the benchmark being used and the health implications associated with any specific benchmark being exceeded.
Appendix 1 to the health risk assessments for each source category contain full discussions of how the modeling file (which is the basis for the risk assessment) was populated with the emissions estimates. Finally, the EPA includes and considers all reported HAP in the risk assessment, but the precision of the evaluation ultimately depends on the quality and amount of health risk information about the HAP at issue. Because the EPA considers all HAP based on the available information, we do not agree with the commenter that the risk analysis is flawed.
Comment: One commenter (0668-0117) stated that the EPA did not provide public notice of all HAPs for which it did not evaluate any quantitative risk, arguing that this is a violation of notice and comment because it prevents commenters from having a meaningful opportunity to present data to EPA that may be useful in EPA's evaluation of the risk from pollutants for which EPA is currently treating a risk as zero. In the commenter's opinion, in the response to comments, EPA must state for public comment and review the set of pollutants or health risks for which it did not assess any quantitative value, or whether there are additional pollutants that fall into this category.
Response: The EPA does not agree with the comment. The proposed residual risk assessment document was available in the docket for each of the three rules at proposal. Table 3.1-1 of each residual risk document clearly indicates which emitted HAP have dose-response values that were used in the residual risk assessment and those for which dose-response values were not available. The source of each dose-response value that was used can be found in Appendix 8 of each residual risk document.
Comment: One commenter (0668-0117) asserted that the EPA must recognize that chronic (non-cancer) risk-causing pollutants have no safe level of exposure, noting that the NAS recommends that cancer and chronic non-cancer risk assessment use the same approach in order to address the fact that very low levels of non-carcinogen exposures can pose health risks. The commenter noted that the use of RfDs for dose-response risk assessments of chronic non-cancer health effects may significantly underestimate risk, because the NAS defines the RfD or RfC as a dose "likely to be without an appreciable risk of deleterious effects" over a lifetime of exposure.
The commenter identified what they see as the problems with traditional toxicology as the basis for risk assessments, including the presumption that health effects are related to dose, and that a dose can be found for virtually all chemicals where no effect is found. The commenter claimed that the greatest public health threat of chemicals is for fetal exposure, meaning that the dose may be less important than the timing, and furthermore that for some toxic chemicals, the clinical effect can actually increase as the chemical concentration decreases, meaning that there is no safe level of exposure. For example, the commenter noted that a 2009 statement by the Endocrine Society stated that "[e]ven infinitesimally low levels of exposure, indeed, any level of exposure at all, may cause endocrine or reproductive abnormalities, particularly if exposure occurs during a critical developmental window. Surprisingly, low doses may even exert more potent effects than higher doses." The commenter also identified a report published in The New England Journal of Medicine, regarding the toxicity of volatilized compounds from oil made these important statements illustrating the risk from small exposures to toxic agents: "Mutagenic effects theoretically can result from a single molecular DNA alteration. Regulatory prudence has led to the use of `one-hit models' for mutagenic end points, particularly cancer, in which every molecule of a carcinogen is presumed to pose a risk."; and "Pregnant women should particularly avoid dermal contact with oil and should avoid areas with visible oil contamination or odors." The commenter also noted that a recent panel of twelve national endocrine disruptor specialists recently stated that "[for] every chemical that we looked at that we could find a low-dose cutoff, if it had been studied at low doses it had an effect at low doses." The commenter further noted that a recent joint public statement by the American College of Obstetricians and Gynecologists and the American Society for Reproductive Medicine addressed the extraordinary vulnerability of in utero development.
Response: The EPA does not agree with the comment and maintains that our chronic dose-response values are reasonable. The chronic noncancer dose-response values used in the RTR program, including those derived by the EPA and similar authoritative agencies (e.g., ATSDR and CalEPA) represent chronic exposure levels that are intended to be health-protective. Those values are derived using an approach that is intended to not underestimate risk in the face of uncertainty and variability. When there are gaps in the available information, UFs are applied to derive reference values that are protective against appreciable risk of deleterious effects. UFs are commonly default values (e.g., factors of 10 or 3) used in the absence of compound-specific data; where data are available, data-derived extrapolation factors may also be developed using compound-specific information. When data are limited, more assumptions are needed and more default factors are used. Thus, there may be a greater tendency to overestimate risk -- in the sense that further study might support development of reference values that are higher (i.e., less potent) because fewer default assumptions are needed. For some pollutants, however, there is a slight possibility that risks could be underestimated. Where data indicate a potential vulnerability of a specific life stage, the EPA includes this information in its derivation of cancer and noncancer dose-response values. In some instances, data are not available for a robust characterization of risk during a specific life stage and, in that case, potential susceptibilities are accounted for by applying the appropriate UFs.
The EPA agrees with the NAS that the recommendations on harmonization of cancer and non-cancer approaches are important issues in risk assessment and the EPA incorporates NAS recommendations as feasible. The NAS has agreed with the EPA, specifically on the derivation methodology of RfCs and RfDs, that the available scientific information does not always allow for assessment derivation issues to be fully considered, and it has reviewed and supported the approaches currently used in the derivation of the RfCs and RfDs. The NAS has also recognized that many of the recommended changes for the IRIS Program will need to be incorporated over a number of years and further recommend continuation of the development of assessments as the recommendations are implemented (i.e., the process should not be halted until all recommendations can be enacted). As such, improvements will be made over time and existing assessments will need to be used in the interim. Further, the EPA has a legal obligation to proceed with regulatory action based on the best available data and tools. Because we use the best available data and tools, apply conservative assumptions, and take into account uncertainties, we tend to err on the side of overestimating risk in determining whether risk is acceptable. The commenter stated that there are problems associated with traditional toxicology presumption that health effects are related to dose; however, the commenter does not provide any information to consider an alternative paradigm to risk assessment that would not include an analysis of dose response relationships in the risk assessment process.
The commenter provided a reference to support the statement that there is no safe level of exposure and that, for fetal exposure, the dose may be less important than the timing, and furthermore that for some toxic chemicals, the clinical effect can actually increase as the chemical concentration decreases. The review article on hormones and endocrine-disrupting chemicals focuses on a broad category of chemicals that appear to act at low concentrations. We disagree with the interpretation of the commenter on the referenced review. First, the authors of the review article do not conclude that there is no safe level of exposure for chemicals in general, not even for endocrine disruptors. We disagree with the comment that clinical effect increases as dose of the chemical decreases; rather, the authors of the review conclude that the effect of low doses of this group of chemicals cannot be predicted by effects observed at high doses, and they encourage investigators to make changes in chemical testing approaches to identify potential endocrine disruptors. We conclude that none of the information or conclusions in the review article conflicts with the EPA's determinations in this regulatory action.
We agree with the comment that the regulatory community, including the EPA, should use conservative approaches to evaluate cancer risks, especially when considering cancer risks to early life stages. When chemical-specific data are available on which age or life-stage specific risk estimates or potencies can be determined, default age-dependent adjustment factors can be applied when assessing cancer risk for early-life exposures to chemicals which cause cancer through a mutagenic MOA. With regard to other carcinogenic pollutants for which early-life susceptibility data are lacking, it is the Agency's long-standing science policy position that use of the linear low-dose extrapolation approach (without further adjustment) provides adequate public health conservatism in the absence of chemical-specific data indicating differential early-life susceptibility or when the MOA is not mutagenicity. The basis for this methodology is provided in the 2005 Supplemental Guidance.
Comment: One commenter (0668-0117) recommended that, as part of the risk assessment, the EPA account for community level vulnerability by including factors to account for increased vulnerability based on demographic differences. The commenter recommended that the EPA revisit or update its presumed acceptable level of cancer risk considering information learned about overburdened community's vulnerability, biomonitoring and other data on adult body burdens of chemicals, and new information on ways to analyze and control the impacts of pollutants on human health. The commenter stated that EPA's failure to account for vulnerability and variability based on the current science, particularly the science addressing early-life and socioeconomic factors in the risk related to exposure, has led EPA to underestimate the health risks to the most-exposed individuals. The commenter suggested that EPA look at, consider, and use the data available from the Center for Disease Control's Environmental Public Health Tracking Program, the ATSDR, and state and local health agencies in its risk assessment.
The commenter (0668-0117) also suggested that the EPA incorporate a more robust analysis of childhood and pre-natal exposure to environmental contaminants into its risk assessment method, citing related recommendations from the EPA's Children's Health Protection Advisory Committee and the EPA's SAB. The commenter also cited methodology changes from OEHHA that may affect the estimation of children's risks.
The commenter (0668-0117) claimed that the EPA underestimates risks to children and from pre-natal and early-life exposures and suggested that the EPA account for increased early-life susceptibility by using age-dependent adjustment factors for all carcinogens emitted by a source category, not just HAP included in the EPA's list of carcinogens that act by a mutagenic MOA.
The commenter (0668-0117) stated that most of EPA's IRIS toxicity threshold values (RfCs and RfDs) used for chronic noncancer risk assessment do not incorporate the latest science on increased susceptibility of children and that EPA needs to account for early exposure and the greater risk to and susceptibility of children to compounds that EPA has recognized are emitted by these source categories in its risk assessment.
The commenter (0668-0117) added that, until the IRIS values fully account for the increased risk caused by early-life exposure to an emitted pollutant, EPA should use the OEHHA child-specific RfDs or benchmarks available to assess chronic non-cancer health risk from ingestion for certain pollutants. EPA should also assess such risk from inhalation by using standard methods to translate these values into child-specific RfCs.
The commenter (0668-0117) suggested that, where child-specific reference values are unavailable, the EPA use a default or UF to account for increased risk from early-life exposures for non-cancer risk, such as the 10X factor enacted by Congress in the FQPA of 1996, to fulfill the CAA's "margin of safety" requirement.
The commenter (0668-0117) stated that the EPA must also assess the starting point or baseline overall health status of the affected individuals and communities using the best available data at a local and national level, including the baseline cancer levels, respiratory problems, and health problems associated with the toxic chemicals emitted by a source category. Doing so would be consistent with the 1999 Residual Risk Report. It would also follow EPA's own statements in the 2014 Second Integrated Urban Air Toxics Report that more work is needed to reduce excess cancer risks in urban areas that continue to face elevated risks.
Response: We disagree with the comment that the risk assessment for these source categories do not consider the groups that may be most at-risk (e.g., children). When the EPA derives exposure RfCs and unit risk estimates for HAP, it also considers the most sensitive populations identified in the available literature and, importantly, these are the values used in our risk assessments. With respect to prenatal exposure in utero specifically, we are unaware of literature that would allow for a robust characterization of risk during this stage of development.
We acknowledge that population subgroups, including children, may have a potential for risk that is greater than the general population due to greater relative exposure and/or greater susceptibility to the toxicant. The assessments we undertake to estimate risk account for this potential vulnerability. With respect to exposure, the risk assessments we perform implicitly account for this greater potential for exposure by assuming lifetime exposure, in which populations are conservatively presumed to be exposed to airborne concentrations at their residence continuously, 24 hours per day for a full lifetime, including childhood. With regard to children's potentially greater susceptibility to non-cancer toxicants, the assessments rely on the EPA's (or comparable) hazard identification and dose-response values that have been developed to be protective for all subgroups of the general population, including children.
For example, a review of the chronic reference value process concluded that the EPA's RfC derivation processes adequately considered potential susceptibility of different subgroups with specific consideration of children, such that the resultant RfC values pertain to the full human population "including sensitive subgroups," a phrase which is inclusive of childhood.[ADD CITATION] With respect to cancer, the EPA uses the age-dependent adjustment factor approach referred to by the commenter, but limits the use of those factors only to carcinogenic pollutants that are known to act via mutagenic MOA, in contrast to the OEHHA approach, which uses them across the board for all carcinogens regardless of MOA. In lieu of chemical-specific data on which age or life-stage specific risk estimates or potencies can be determined, default age dependent adjustment factors can be applied when assessing cancer risk for early-life exposures to chemicals that cause cancer through a mutagenic MOA. With regard to other carcinogenic pollutants for which early-life susceptibility data are lacking, it is the EPA's long-standing science policy position that use of the linear low-dose extrapolation approach (without further adjustment) provides adequate public health conservatism in the absence of chemical-specific data indicating differential early-life susceptibility or when the MOA is not mutagenicity. The basis for this methodology is provided in the 2005 Supplemental Guidance.
The estimated risks must be considered in the context of the full set of assumptions used for this risk assessment. Our unit risk estimates for HAP are considered a plausible upper-bound estimate with an appropriate age dependent adjustment; actual potency is likely to be lower and some of which could be as low as zero. Our chronic non-cancer reference values have been derived considering the potential susceptibility of different subgroups, with specific consideration of children.
We disagree with the general comment that the EPA should adopt the OEHHA child-protective scientific approach on deriving health benchmarks. The EPA has an approach for selecting appropriate health benchmark values and in general, this approach places greater weight on the EPA-derived health benchmarks than those from other agencies. The approach favoring the EPA benchmarks (when they exist) has been endorsed by the SAB and ensures use of values most consistent with well-established and scientifically-based EPA science policy. The EPA is currently evaluating the most appropriate use for the OEHHA child-specific RfDs. We note that there are currently no such values for HAP inhalation, therefore, the current utility may be limited to PB-HAP, which may be associated with non-negligible ingestion exposures. This evaluation on the appropriateness of these values in the context of the RTR Program and EPA science policy is necessary prior to using these child-specific RfDs.
The EPA also disagrees with the commenter in that a children's default safety factor of 10 or more should be added to the EPA's reference values. In response to the 10X factor enacted by Congress in the FQPA (1996) to the EPA non-cancer reference value derivation, the EPA evaluated their methods for considering children's risk in the development of reference values. As part of their response, the U.S. EPA (i.e., the Science Policy Council and Risk Assessment Forum) established the RfD/RfC Technical Panel to develop a strategy for implementing the FQPA and examine the issues relative to protecting children's health and application of the 10X safety factor. One of the outcomes of the Technical Panel's efforts was an in-depth review of a number of issues related to the RfD/RfC process (U.S. EPA 2002). The most critical aspect in the derivation of a reference value pertaining to the FQPA has to do with variation between individual humans and is accounted for by a default UF when no chemical-specific data are available. The EPA reviewed the default UF for inter-human variability and found the EPA's default value of 10 adequate for all susceptible populations, including children and infants. The EPA also recommended the use of chemical-specific data in preference to default UFs when available and is developing EPA guidance to facilitate consistency in the development and use of data-derived extrapolation factors for RfCs and RfDs. Additionally, the EPA also applies a database UF, which is intended to account for the potential for deriving an under-protective RfD/RfC as a result of an incomplete characterization of the chemical's toxicity. In addition to the identification of toxicity information that is lacking, review of existing data may also suggest that a lower reference value might result if additional data were available.
In conclusion, our chronic non-cancer reference values have been derived considering the potential susceptibility of different subgroups, with specific consideration of children. In addition, an extra 10X UF is not needed in the RfC/RfD methodology because the currently available factors are considered sufficient to account for uncertainties in the database from which the reference values are derived. After considering these and other factors, we continue to consider the current NESHAP for these source categories to provide an ample margin of safety (consistent with the Benzene NESHAP framework).
Comment: According to one commenter (0668-0117), the EPA's multipathway risk assessment falls short because the EPA did not complete this analysis for all persistent or bioaccumulative pollutants, it did not use "allowable" emissions for this assessment, and it did not assess all exposure routes  -  particularly for children. The commenter states that it is also problematic that the EPA failed to use the information it found from the multipathway analysis in its overall risk analysis, because it did not add the multipathway risk found to the inhalation risk.
The commenter (0668-0117) stated that the multipathway risk screening assessment was restricted to only those contaminants identified in the 2003 Risk Assessment Guidance as being both persistent and bioaccumulative in the environment (i.e., PB-HAPs). They state that this list of 14 PB-HAPs is incomplete as it ignores other HAPs which present a multipathway risk.
The commenter (0668-0117) described why they believe the 2003 Guidance is deficient and conclude that the EPA must perform a full multipathway risk assessment for all HAP (including antimony and nickel) emitted by these source categories. The commenter noted that OEHHA has recommended multipathway assessment based on scientific research and developed a method to conduct this assessment, and the EPA should follow its lead. The commenter provided additional information for each of the pollutants for the EPA's consideration, including information from recent studies showing the impacts of ingestion. The commenter concluded that the EPA simply may not assume that the ingestion and other multipathway risks are zero for these pollutants because doing so when science shows otherwise is arbitrary and capricious. The commenter added that the failure to assess multipathway risk from exposure to these HAPs, both individually and cumulatively, results in an underestimate of the health risks of HAP emissions from these source categories. The commenter added that this provides further support for the finding of unacceptability and the need for strong health risk-based standards that assure an "ample margin of safety to protect public health" under section 7412(f)(2).
The commenter (0668-0117) further argued that the EPA must use the multipathway assessment appropriately, by adding the risk found there to the inhalation risks found, and then proceeding with the required section 112(f)(2) analysis to determine whether or not that total level of risk is acceptable, and what standards are needed to reach an acceptable level and also to provide an ample margin of safety. The commenter added that because the EPA treated multipathway risk separately from inhalation risk in its analysis, listing each of them, but not adding them together in an appropriate manner to recognize their combined impact on the most exposed people, the EPA thus failed to adequately assess or address the full risk to the most-exposed person from the combined impact of both inhalation and other routes of exposure, such as ingestion, breast-milk exposure, and other pathways.
Response: The EPA does not agree that the approach to conducting multipathway risk assessments is flawed or that EPA must expand the pollutants subject to such assessments at this time. As stated in the preamble to the proposed rule (83 FR 46262, p. 46275), for the Surface Coating of Large Appliances; the Printing, Coating, and Dyeing of Fabrics and Other Textiles; and Surface Coating of Metal Furniture source categories, we did not identify emissions of any PB- - HAP. Because we did not identify PB-HAP emissions, no further evaluation of multipathway risk was conducted for these source categories.
The HAP listed by the commenter (naphthalene, antimony and, nickel) have not been identified by the EPA as persistent bioaccumulative HAP. We disagree that the risk assessment was inadequate because it did not include multipathway risk assessments for these HAP. In the Air Toxics Assessment Library, we developed the current PB-HAP list considering all of the available information on persistence and bioaccumulation (see http://www.epa.gov/ttn/fera/risk_atra_main.html). This list reviewed HAP identified as PB-HAP by other EPA Program Offices (e.g., the Great Waters Program), as well as information from the PBT profiler (see http://www.pbtprofiler.net/). This list was peer-reviewed by the SAB and found to be acceptable and, therefore, we consider it to be reasonable for use in the RTR program. Based on these sources and the limited available information on the persistence and bioaccumulation of other HAP, we do not think that the potential for multipathway risk from the other HAP cited by the commenter warrants a multipathway assessment.
Because these categories do not emit any PB-HAP currently on the list and the EPA is not expanding the list at this time, the Agency disagrees with the comment that multipathway risk assessments are necessary for these source categories.
Comment: One commenter (0668-0117) argued that, in the course of determining acute risk, the EPA did not adequately document the development of the acute risk emission multipliers and that the multipliers the EPA used would underestimate acute health risks. The commenter noted that the EPA chose to base its assumption of peak emissions on estimates, assuming only a slightly higher amount during acute emissions periods than other times (e.g., a multiplier of 1.2, 1.7, 1.8 for each source category). The commenter argued that, among other things, the ratio of mean to peak emissions will vary depending on whether the emissions from the sources are controlled by a pollution control device and whether the processes involved are continuous or batch processes. The commenter argued that the EPA provided no detailed evaluation of the data or any explanation of how its multiplier is the most accurate estimate, or how likely it is that emissions are not much higher during certain periods.
Response: The EPA disagrees with the commenter that the development of the acute risk multipliers was not adequately documented because the development of the emissions multipliers was documented in Appendix 1 of the risk assessment report for each source category. The EPA believes that the multipliers chosen are accurate for these source categories. Each of these source categories perform surface coating generally using continuous processes. In two of the source categories (Large Appliances and Metal Furniture), add-on controls are only rarely used to maintain compliance with the NESHAP, so emissions are not likely to be affected by the malfunction of a control device. In the Printing, Coating, and Dyeing of Fabrics and Other Textiles source category, add-on controls are used in the fabric coating processes. However, in the event of a control device malfunction, these coating processes can be quickly stopped (e.g., the coating heads and can be retracted from the web substrate and no additional coating applied) and excess emissions would be minimized. This is different from other industries in which it may take several hours to completely shut down a process and cease air emissions. Thus, for all three source categories, the multiplier does not need to be nearly as high as it would be for other industries. For these reasons, the EPA believes that the factors used in the acute health risk analyses were appropriate for each of the source categories.
Comment: One commenter (0668-0117) noted that the EPA recognizes that it must assess the combined impact of cancer risks from different carcinogens to create a combined cancer risk from inhalation and that it must assess the combined chronic non-cancer risk for different chemicals that affect the same target organ. The commenter argued that the EPA should apply the same scientific principles to recognize that it also must combine and look at the whole picture of all other kinds of risk from multiple pollutants.
The commenter (0668-0117) stated that EPA fails to reach a combined cancer risk value that includes inhalation and multipathway risks of cancer, and that this is unlawful and arbitrary. The commenter argued the EPA must account for the aggregate impact of inhalation and multipathway cancer and chronic non-cancer risk by adding each type of similar risk together for all pollutants.
The commenter (0668-0117) stated that, to look overall at a person's exposure, the EPA must add inhalation and multipathway risk. Failing to add up each type of risk in order to come up with a total cancer risk number and a total non-cancer number, and then a cumulative burden metric, makes EPA's overall risk assessment incomplete. The commenter stated that EPA must assess the total and synergistic chronic non-cancer risk for different pollutants that may work in different ways than EPA has acknowledged here.
The commenter (0668-0117) added that EPA should apply these same principles to create a mechanism for assessing the total acute risk to chemical mixtures, such as the target organ-specific hazard index (TOSHI) for chronic risk, that aggregates the acute impacts on the same organ systems for all pollutants. EPA's decision to assess acute risks solely chemical by chemical, when it knows the collection of HAPs is being released together, is unlawful and arbitrary. The result is an underestimation of the full acute health risks to which the most-exposed individual and nearby community members are exposed.
Response: We have combined risk assessment results to the extent that it is appropriate to do so and disagree with the comment that we failed to consider or account for cumulative risk. The EPA conducted an assessment of the cumulative cancer risks from all emitted carcinogens and the cumulative noncancer hazard indices from all emitted non-carcinogens that are HAPs affecting the same target organ system for both the source category emissions and the facility-wide emissions. To address the effect of mixtures of carcinogens, the individual cancer risks for the source category were aggregated for all carcinogens. In assessing the noncancer hazard from chronic exposures for pollutants that have similar modes of action or that affect the same target organ, we aggregated the HQs to provide a TOSHI. We do not use a TOSHI approach for our acute analyses nor do we combine the results of our inhalation and multipathway assessments. We further modeled whole-facility risks for both chronic cancer and non-cancer impacts to understand the risk contribution of the co-located sources within each of the three source categories.
For each source category, the EPA conducted an assessment of the cumulative cancer risks from all emitted carcinogens and the cumulative noncancer hazard indices from all emitted non-carcinogens that are HAPs affecting the same target organ system for both the source category emissions and the facility-wide emissions.
The EPA modeled whole-facility risks for both chronic cancer and non-cancer impacts to understand the risk contribution of the sources within each source category. The individual cancer risks for the source categories were aggregated for all carcinogens. In assessing noncancer hazard from chronic exposures for pollutants that have similar modes of action or (where this information is absent) that affect the same target organ, we aggregated the HQs. This process creates, for each target organ, a TOSHI, defined as the sum of HQs for individual HAP that affect the same organ or organ system. All TOSHI calculations presented here were based exclusively on effects occurring at the "critical dose" (i.e., the lowest dose that produces adverse health effects).
As described in the risk assessment document available in the docket, we do not sum results of the acute noncancer inhalation assessment to create a combined acute risk number that would represent the total acute risk for all pollutants that act in a similar way on the same organ system or systems (similar to the chronic TOSHI). The worst-case acute screen is a conservative scenario. That is, the acute screening scenario assumes worst-case meteorology, peak emissions for all emission points occurring concurrently and an individual being located at the site of maximum concentration for an hour. Thus, as noted in the residual risk assessment document for each source category, because of the conservative nature of the acute inhalation screening and the variable nature of emissions and potential exposures, acute impacts were screened on an individual pollutant basis, not using the TOSHI approach.
Comment: One commenter (0668-0117) argued that the EPA must create a metric to assess the total and cumulative risk burden, rather than only looking at each type of risk in a discrete, separate way. The commenter argued that EPA should be integrating its assessments and performing a "comprehensive risk assessment" as the NAS has emphasized. The commenter stated that after first assessing the total cancer, chronic non-cancer, and acute risks, for both inhalation and multipathway exposure, EPA also must create a metric to assess the total bundle of risks, and EPA must aggregate health risk for each pollutant, and each type of health risk, to create a cumulative risk determination for the individual "most exposed" to emissions as the CAA requires.
The commenter (0668-0117) stated that unless and until EPA creates a combined health risk metric, it is unclear how it can make an ample margin of safety determination that is based on the full picture of health risk for a source category and that can be compared to other source categories. The commenter argued that EPA must assess the full cumulative burden for public health, and by failing to perform a full, cumulative risk assessment, EPA fails to gather the information needed to assess whether the risk to public health is acceptable under CAA § 7412(f)(2).
Response: We disagree that this type of comprehensive assessment, which the commenter believes is mandated by the CAA, is required. The CAA requires that EPA regulate the risks from the source category, and incorporates the approach outlined in the Benzene NESHAP, which is based on risk acceptability and ample margin of safety decisions. The EPA's current approach is consistent with the approach in the Benzene NESHAP and that action does not require the analysis suggested by the comment.
Comment: One commenter (0668-0117) argued that the EPA's risk assessment must account for the cumulative impact from exposure to multiple source categories' air emissions. The commenter stated that this is in keeping with a SAB May 2010 recommendation to incorporate cumulative risk into the residual risk analysis. The commenter stated that EPA should combine current baseline emissions, exposures, and health impacts in addition to those of the specific source category, as well as evaluate background exposures and vulnerability factors such as inequality. The commenter recommended that EPA draw on the OEHHA cumulative assessment approach for its risk assessment or incorporate an explicit default or UF to adjust the degree to which each source category is contributing to the total risk experienced by the most-exposed individuals. For a source category in an area with up to 10 other HAP-emitting facilities, the commenter stated that this default or UF should equal at least 10.
Response: We disagree with the claim that additional quantitative assessment of risks from sources outside the source category is required for this rulemaking. Section 112(f) requires the EPA to perform a review of whether there is risk remaining from emissions from a source category after promulgation of the technology-based MACT standards for that source category. To this end, the EPA conducts a comprehensive assessment of the risks associated with exposure to the HAP emitted by the source category and supplements that with additional information that is available about other possible concurrent and relevant risks. The incorporation of additional background concentrations from the environment in our risk assessments (including those from mobile sources and other industrial and area sources) would be technically challenging, and such analyses are neither mandated nor barred from our overall risk analysis approach. In developing the decision framework in the Benzene NESHAP currently used for making residual risk decisions, the EPA rejected approaches that would have mandated consideration of background levels of pollution in assessing the acceptability of risk, concluding that comparison of acceptable risk should not be associated with levels in polluted urban air (54 FR 38044, 38061, September 14, 1989). Background levels (including natural background) are not barred from the EPA's ample margin of safety analysis, and the EPA may consider them, as appropriate and as available, along with other factors, such as cost and technical feasibility, in the second step of its section 112(f) analysis. This assessment excludes background contributions because the available data are of insufficient quality upon which to base a meaningful analysis. Further, as explained at proposal, our approach here is also consistent with the approach we took regarding this issue in the HON RTR (71 FR 76603, December 21, 2006), which the court upheld in the face of claims that the EPA had not adequately considered background concentrations. (NRDC v. EPA, 529 F.3d 1077 (D.C. Cir. 2008)).
Comment: One commenter (0668-0117) argued that EPA should consider reforming its risk assessments to support reducing risks to the lowest possible level to protect public health. The commenter believed that the 100-in-1 million lifetime cancer risk cannot be considered safe or "acceptable." The commenter disagreed with EPA basing various types of health risks on the Survey of Societal Risk (July 1988) and stated that these should be based on scientific information about cancer risk.
The commenter recommended that the EPA revisit or update its presumed acceptable level of cancer risk considering information learned about children's and overburdened community's vulnerability, biomonitoring and other data on adult body burdens of chemicals, and new information on ways to analyze and control the impacts of pollutants on human health.
Response: We disagree with the commenter that 100-in-1 million lifetime cancer risk cannot be considered acceptable. In 1990, Congress codified in section 112(f)(2)(B) of the CAA the Benzene NESHAP approach we use for our residual risk analyses and that action included a finding that risks at (and above) 100-in-1 million lifetime cancer risk were acceptable. We note that the 100-in-1 million cancer risk is not a bright line indicating that risk is "acceptable"; rather, this health metric is considered in conjunction with a variety of health factors and their associated uncertainties to determine the acceptable risk for a source category. Where we conclude that the risk is not acceptable, we cannot and do not consider costs in requiring controls to bring risks down to an acceptable level. However, the analysis of whether risk is acceptable is not the endpoint. Once we determine that controls are sufficient to ensure that risk is acceptable, we again review the health metrics (e.g., cancer and chronic non-cancer risks) and their associated uncertainties in conjunction with the costs of controls, technical feasibility, and other relevant factors, to determine whether additional controls should be required to provide an ample margin of safety.
We further note that we generally draw no bright lines of acceptability regarding cancer or non-cancer risks from source category HAP emissions, and that it is always important to consider the specific uncertainties of the emissions and health effects information regarding the source category in question when deciding exactly what level of cancer and non-cancer risk should be considered acceptable. In addition, the source category-specific decision of what constitutes an acceptable level of risk should be a holistic one; that is, it should simultaneously consider all potential health impacts  -  chronic and acute, cancer and non-cancer, and multipathway  -  along with all their uncertainties, when determining the acceptable level of source category risk. Experience with source category rulemakings in the past tells us that this means drawing bright lines for such decision-making is impossible. The Benzene NESHAP decision framework of 1989 acknowledged this; in today's world, such flexibility is even more imperative, because new information relevant to the question of risk acceptability is being developed all the time, and the accuracy and uncertainty of each piece of information must be considered in a weight-of-evidence approach for each decision. This relevant body of information is growing fast (and its growth will accelerate), necessitating a flexible weight-of-evidence approach that acknowledges both complexity and uncertainty in the simplest and most transparent way possible. While this challenge is formidable, it is nonetheless the goal of the EPA's RTR decision-making, and it is the goal of the risk assessment to provide the information to support the decision-making process.
The estimated risks must be considered in the context of the full set of assumptions used for this risk assessment. Our unit risk estimates for HAP are considered a plausible upper-bound estimate with an appropriate age dependent adjustment; actual potency is likely to be lower and some of which could be as low as zero. Our chronic noncancer reference values have been derived considering the potential susceptibility of different subgroups, with specific consideration of children. In addition, an extra UF is not needed in the RfC/RfD methodology because the currently available factors are considered sufficient to account for uncertainties in the database from which the reference values are derived. After considering these and other factors, we continue to consider the risks from HAP emissions for these source categories to provide an ample margin of safety (consistent with the Benzene NESHAP framework).
Comment: One commenter (0668-0117) argued that the EPA has not justified the proposal that the risk assessment results found by the EPA are acceptable, even though for two source categories (Textiles, MIR of 9-in-1-million; Metal Furniture (7-in-1 million), they are 7-9 times the "aspirational goal" of 1-in-1 million from any given single source category, stated by the statute in § 7412(f)(2), and for two source categories (Metal Furniture and Large Appliances), EPA finds acute risk is an HQ of 2, two times EPA's threshold for acute health risks. EPA has failed to show why these risks should be considered "acceptable."
Response: As indicated in the proposal preamble, 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) of approximately [1-in-10 thousand] [i.e., 100-in-1 million]." 54 FR 38045, September 14, 1989. The level of the MIR is only one factor to be weighed in determining acceptability of risks. The Benzene NESHAP explained that "an MIR of approximately 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 MIR less than the presumptively acceptable level is unacceptable in the light of other health risk factors." Id. at 38045. These "other health risk factors" include, the hazard index for chronic exposures to HAP with the potential to cause noncancer health effects, the HQ for acute exposures to HAP with the potential to cause noncancer health effects, estimates of the distribution of cancer risks within the exposed populations, and cancer incidence.
For the Surface Coating of Large Appliances source category, the risk analysis indicates that the cancer risks to the individual most exposed could be up to 0.9-in-1 million due to actual emissions and up to 1-in-1 million based on allowable emissions. These risks are considerably less than 100-in-1 million, which is the presumptive upper limit of acceptable risk. The risk analysis also shows very low cancer incidence (0.0001 cases per year for actual emissions and 0.0002 cases per year for allowable emissions), and we did not identify potential for adverse chronic noncancer health effects.
For the Printing, Coating, and Dyeing of Fabrics and Other Textiles source category, the risk analysis indicates that the cancer risks to the individual most exposed could be up to 9-in-1 million due to actual emissions and up to 10-in-1 million based on allowable emissions. These risks are considerably less than 100-in-1 million, which is the presumptive upper limit of acceptable risk. The risk analysis also shows very low cancer incidence (0.002 cases per year for actual emissions and allowable emissions), and we did not identify potential for adverse chronic noncancer health effects. The acute noncancer risks based on actual emissions is below an HQ of 1 for all facilities (maximum of 0.6 for formaldehyde). In addition, the risk assessment indicates no significant potential for multipathway health effects.
For the Surface Coating of Metal Furniture source category, the risk analysis indicates that the cancer risks to the individual most exposed could be up to 7-in-1 million due to actual emissions and up to 10-in-1 million based on allowable emissions. These risks are considerably less than 100-in-1 million, which is the presumptive upper limit of acceptable risk. The risk analysis also shows very low cancer incidence (0.0004 cases per year for actual emissions or 1 case in every 2,500 years, and 0.0008 cases per year for allowable emissions or 1 case in every 1,250 years), as well as no potential for adverse chronic noncancer health effects.
For the Surface Coating of Large Appliances and the Surface Coating of Metal Furniture Source Categories, the acute screening analysis resulted in a maximum acute noncancer HQ of 2 based on the acute REL for ethylene glycol monomethyl ether. For acute screening-level assessments, to better characterize the potential health risks associated with estimated worst-case acute exposures to HAP, we typically examine a wider range of available acute health metrics than we do for our chronic risk assessments. This is in acknowledgement that there are generally more data gaps and uncertainties in acute reference values than there are in chronic reference values. By definition, the acute REL represents a health-protective level of exposure, with effects not anticipated below those levels, even for repeated exposures; however, the level of exposure that would cause health effects is not specifically known. As the exposure concentration increases above the acute REL, the potential for effects increases. Therefore, when an REL is exceeded and an AEGL-1 or ERPG-1 is available (i.e., levels at which mild, reversible effects are anticipated in the general population for a single exposure), we typically use them as additional comparative measures. However, neither of these is available for ethylene glycol monomethyl ether. Taking into account the conservatism included in the acute screening-level assessment, including use of an acute REL for a highly toxic glycol ether, we would not expect acute exposures at levels that would cause adverse effects.