Court Opinion

ID: 9410984
Source: CourtListenerOpinion
Date Created: 2023-07-25 15:01:42.786992+00
Date Added: 2024-06-11T17:21:01.991426
License: Public Domain

United States Court of Appeals
         FOR THE DISTRICT OF COLUMBIA CIRCUIT

Argued November 16, 2022                Decided July 25, 2023

                         No. 21-1187

 PUBLIC EMPLOYEES FOR ENVIRONMENTAL RESPONSIBILITY,
                     PETITIONER

                              v.

           ENVIRONMENTAL PROTECTION AGENCY,
                     RESPONDENT

   On Petition for Review of a Final Agency Action of the
             Environmental Protection Agency

     Paula Dinerstein argued the cause and filed the briefs for
petitioner.

     Sarah Izfar, Attorney, U.S. Department of Justice, argued
the cause for respondent. With her on the brief was Todd Kim,
Assistant Attorney General.

    Wayne J. D'Angelo was on the brief for amicus curiae
Corrosivity Coalition in support of respondent.

   Before: HENDERSON and PAN, Circuit Judges, and
EDWARDS, Senior Circuit Judge.
                                 2
    Opinion for the Court filed by Circuit Judge PAN.

      PAN, Circuit Judge: The Resource Conservation and
Recovery Act of 1976 (“RCRA”) governs the treatment,
storage, and disposal of hazardous waste. In implementing the
RCRA, the Environmental Protection Agency (“EPA”)
promulgated a rule under which waste is deemed “hazardous”
if it is “corrosive.” A scientist and a public interest group
unsuccessfully petitioned the EPA to expand the definition of
“corrosive” wastes so that more wastes would be subject to the
RCRA’s most stringent requirements. The question presented
in this case is whether the EPA properly declined to revise its
corrosivity regulation. Because several of the petitioner’s
arguments are time-barred and the EPA otherwise acted within
its broad discretion, we deny the petition for review.

                      I.      BACKGROUND

        A. The 1980 Rulemaking

     The cornerstone of the RCRA is Subtitle C, which imposes
strict “cradle to grave” requirements “for the treatment,
storage, and disposal” of wastes classified as “hazardous.”
Cement Kiln Recycling Coal. v. EPA, 493 F.3d 207, 211 (D.C.
Cir. 2007) (cleaned up); see generally 42 U.S.C. §§ 6921–
6939g. The statute, however, provides “only a broad definition
of ‘hazardous waste’.” Nat. Res. Def. Council, Inc. v. EPA, 25
F.3d 1063, 1065 (D.C. Cir. 1994). Specifically, § 6903(5) of
the RCRA defines “hazardous waste” as:

        [A] solid waste, or combination of solid
        wastes, 1 which because of its quantity,

1
    As used in the RCRA’s definition of hazardous waste, “solid
waste” is a term of art that can include liquid wastes. See 42 U.S.C.
                                 3
        concentration, or physical, chemical,            or
        infectious characteristics may—

            (A) cause, or significantly contribute to an
                increase in mortality or an increase in
                serious irreversible, or incapacitating
                reversible, illness; or

            (B) pose a substantial present or potential
                hazard to human health or the
                environment when improperly treated,
                stored, transported, or disposed of, or
                otherwise managed.

42 U.S.C. § 6903(5). In sum, “hazardous wastes” are
characterized by their potential to damage human health or the
environment, either intrinsically or when mismanaged.

     The EPA bears responsibility for identifying which wastes
are “hazardous” and therefore subject to Subtitle C regulation.
The RCRA directs the agency to “develop and promulgate
[regulations] identifying the characteristics of hazardous waste,
and for listing hazardous waste, . . . taking into account toxicity,
persistence, and degradability in nature, potential for
accumulation in tissue, and other related factors such as
flammability,      corrosiveness,       and     other   hazardous
characteristics.” See 42 U.S.C. § 6921(a)–(b)(1). The EPA
finalized regulations that implement the statute in 1980. See
Hazardous Waste Management System: Identification and
Listing of Hazardous Waste, 45 Fed. Reg. 33,084 (May 19,
1980). Under the EPA’s regulations, the agency can “list”
individual wastes as hazardous, see 40 C.F.R. §§ 261.11,
261.30–.33, or it can specify certain “characteristics” that

§ 6903(27); Ass’n of Battery Recyclers, Inc. v. EPA, 208 F.3d 1047,
1056 n.5 (D.C. Cir. 2000).
                                    4
render a substance hazardous, see 40 C.F.R. §§ 261.10,
261.20–.24. The 1980 rules “identified four characteristics of
hazardous wastes: ignitability, corrosivity, reactivity[,] and
. . . toxicity.” Am. Petrol. Inst. v. EPA, 906 F.2d 729, 733 (D.C.
Cir. 1990) (per curiam); see also 40 C.F.R. §§ 261.21–.24.
“Any solid waste exhibiting one or more of these
characteristics is automatically deemed a ‘hazardous waste’
subject to regulation under Subtitle C of the RCRA even if it is
not a ‘listed’ waste.” Am. Petrol. Inst., 906 F.2d at 733.

     This case concerns the characteristic of corrosivity. See
40 C.F.R. § 261.22. The EPA has construed “corrosive” to
mean “the property that makes a substance capable of
dissolving material with which it comes in contact.” See
Background Doc. to 1980 Corrosivity Characteristic
Regulation (May 2, 1980) (“1980 Background Doc.”) at 1.
Corrosive materials are dangerous because they can “mobilize
toxic metals, corrode waste storage containers, corrode skin
and eyes, and cause damage to aquatic life.” See Hazardous
Waste Management System; Tentative Denial of Petition to
Revise the RCRA Corrosivity Hazardous Characteristic, 81
Fed. Reg. 21,295, 21,300 (Apr. 11, 2016) (“Proposed Denial”).
As relevant here, the 1980 regulations define as “corrosive”
any waste that: (1) “has a pH less than or equal to 2 or greater
than or equal to 12.5”; and (2) “is aqueous.” 40 C.F.R.
§ 261.22(a)(1). 2 pH is a scientific measurement of the acidity

2
        The corrosivity characteristic regulation provides, in relevant
part:

           (a) A solid waste exhibits the characteristic of
               corrosivity if a representative sample of the
               waste has . . . the following properties:
               (1) It is aqueous and has a pH less than or equal
                   to 2 or greater than or equal to 12.5, as
                   determined by a pH meter using Method
                                5
or basicity of a substance. A pH of 7 is neutral, neither acidic
nor basic. A pH below 7 indicates that a substance is acidic,
while a pH above 7 indicates that a substance is basic
(sometimes called alkaline). The pH scale is logarithmic, so a
substance with pH 9 is ten times more basic than a substance
with pH 8. See 81 Fed. Reg. at 21,298. “Aqueous” is not
defined in the regulation. For present purposes, “aqueous”
effectively means liquid or semi-liquid. Cf. 1980 Background
Doc. at 20 (noting that the EPA declined to regulate non-
aqueous wastes as corrosive because “approximately 90% of
all hazardous wastes are in liquid or in semi-liquid form”); see
also Letter from David Bussard, Dir. of Characterization &
Assessment Div., EPA, to David S. Parsons, Wis. Dep’t of Nat.
Res. (Jan. 7, 1993), https://perma.cc/TAC8-QUFG (EPA
guidance defining “aqueous” as “amenable to pH
measurement”).

      The EPA apparently relied on erroneous information when
it set the upper limit of the corrosivity characteristic regulation
at pH 12.5. The agency’s background document to its 1978
notice of proposed rulemaking stated: “It has been suggested
that pH extremes . . . above 11.5 are not tolerated by the body,
and contact will often result in tissue damage.” Background
Doc. to 1978 Proposed Corrosivity Characteristic Regulation
(Dec. 15, 1978) (“1978 Background Doc.”) at 8. It appears that
the EPA mistakenly believed that its only source for the cited
pH 11.5 level, the International Labour Office’s 1972
Encyclopedia of Occupational Health and Safety (“ILO
encyclopedia”), relied on “studies . . . conducted on corneal

                9040C in “Test Methods for Evaluating
                Solid Waste, Physical/Chemical Methods,”
                EPA Publication SW-846, as incorporated
                by reference in § 260.11 of this chapter.

40 C.F.R. § 261.22(a)(1).
                                 6
[i.e., eye] tissue which is more sensitive to injury than skin.”
Id. 3 In fact, the ILO encyclopedia did not make any reference
to studies performed on corneal tissue, nor did it suggest that
skin tissue can tolerate higher pH substances than eye tissue.
The EPA nevertheless reasoned that, because eye tissue is more
sensitive to injury than skin, an upper pH limit of 12.0 would
provide “sufficient protection . . . to those exposed to caustic
wastes.” Id.

     In the final 1980 rulemaking, the agency further raised the
upper threshold to pH 12.5, after receiving comments that “the
proposed pH limits were unduly stringent . . . [and] would
include many otherwise non-hazardous lime-stabilized wastes
and sludges, thereby discouraging use of this valuable
treatment technique.” 45 Fed. Reg. at 33,109. The EPA agreed
that the proposed limit of pH 12.0 was too low because lime-
treated wastewater sludges, “which generally have a pH
between 12.0 and 12.5 . . . can be put to agricultural and other
beneficial uses.”      See 1980 Background Doc. at 11.
“Accordingly, the Agency . . . adjusted the upper limit to pH
12.5 to exclude such wastes from the system.” Id. The
agency’s assessment of the safety of lime-treated sludges,
however, also relied on the erroneous belief that the relevant

3
     The ILO encyclopedia was the only evidence the agency relied
on with respect to the pH levels considered safe for human exposure.
See 1980 Background Doc. at 5, 39. The ILO encyclopedia
explained that “[t]he skin, eyes and digestive system are the most
commonly affected parts of the body. . . . Extremes above pH 11.5
or below 2.5 are not tolerated by the body and will almost always
result in irreversible tissue damage.” J.A. 31.
                                 7
pH studies were performed on eye tissue. 4 Nevertheless, the
upper pH threshold of 12.5 was not challenged at the time of
the 1980 rulemaking, and it remains the standard today. See 40
C.F.R. § 261.22(a)(1).

     Before the EPA limited corrosivity to “aqueous”
substances in the final 1980 rulemaking, it solicited comments
on whether “solid [i.e., non-aqueous] waste which forms
aqueous solutions of high or low pH” should also be deemed
corrosive. See Hazardous Waste Guidelines and Regulations,
43 Fed. Reg. 58,946, 58,952 (Dec. 18, 1978). “A few
comments . . . advocated including solids in the corrosivity
characteristic but none described situations where the improper
disposal of such wastes would be likely to cause damage.” 45
Fed. Reg. at 33,109. Given that “the great majority of wastes
are presumed to be in liquid or semi-liquid form,” the agency
decided that it would not “address corrosive solids at this time,”
but would revisit the issue “if the need for more control
becomes apparent.” Id. The “aqueous” requirement was not
challenged at the time of the 1980 rulemaking, and it remains
part of the corrosivity characteristic regulation today. See 40
C.F.R. § 261.22(a)(1).

        B. The 2011 Petition for Rulemaking

    In 2011, Dr. Cate Jenkins, a since-retired EPA scientist,
and Public Employees for Environmental Responsibility
(“PEER”), an environmental organization, petitioned the EPA

4
     The agency’s 1980 rule explained that “to a significant extent,
EPA based the proposed pH levels on studies demonstrating a
correlation between pH and eye tissue damage. Since eye tissue is
considered to be more sensitive than other human tissue, the
proposed pH levels were unnecessarily conservative and had the
unintended effect of inhibiting the use of such beneficial processes
as the lime stabilization of wastes.” 45 Fed. Reg. at 33,109.
                               8
to amend the corrosivity characteristic regulation. See Pet. for
Rulemaking. Their petition for rulemaking requested that the
agency: (1) “revise the pH level associated with alkaline
corrosivity . . . from a value of 12.5 to 11.5”; and (2) “delete
the specification that only wastes that are ‘aqueous’ are subject
to regulation.” Id. at 5.

     The petition argued that the upper pH threshold should be
lowered to pH 11.5 because the 1980 rulemaking setting the
threshold at pH 12.5 was based on inaccurate information and
is out of step with other measures of corrosivity adopted by
international organizations. The petitioners claimed that “in
the original 1980 regulation, EPA knowingly falsified the pH
level[] known to cause irreversible corrosive damage to human
tissues (chemical burns) for alkaline (caustic) corrosive
materials.” Id. at 3. Specifically, PEER and Dr. Jenkins
asserted that the EPA incorrectly claimed to be “incorporating”
the ILO encyclopedia’s threshold of “a pH greater than 12.5,”
when “[i]n fact, the [ILO] threshold for alkaline corrosivity was
a pH level greater than 11.5.” Id.; see also id. at 25. The
petition for rulemaking also noted that two international
systems for evaluating the dangerousness of waste products,
the Basel Convention and the United Nations Globally
Harmonized System (“GHS”), use pH 11.5 as a safety
threshold. See id. at 8, 14, 24; see also Basel Convention on
the Control of Transboundary Movements of Hazardous
Wastes and Their Disposal, Mar. 22, 1989, 1673 U.N.T.S. 57;
U.N. Econ. Comm’n for Europe, Globally Harmonized System
of Classification and Labelling of Chemicals (GHS) § 3.2.3.1.2
(1st ed. 2003), https://perma.cc/B4YZ-55NF. Moreover, the
petitioners argued that the EPA improperly decided in 1980 to
raise the proposed pH threshold to 12.5 in order to avoid
subjecting the commercial use of lime-treated waste sludges to
regulation under Subtitle C. See id. at 10–11.
                               9
     With respect to the regulation’s requirement that corrosive
wastes be “aqueous,” the petitioners asserted that new evidence
supported regulating non-aqueous corrosive substances as
hazardous wastes. The post-1980 evidence they cited falls into
three categories. First, PEER and Dr. Jenkins relied on
research into the respiratory health effects of the dust created
by the 9/11 terrorist attacks on the World Trade Center. See id.
at 4 (“The corrosivity of [World Trade Center] dust has been
attributed by medical researchers as a major causative factor in
the respiratory symptoms suffered by First Responders and
others after 9/11.”), 15–19, 21–24, 28–34. Second, the
petitioners cited evidence concerning the dangers of cement
kiln dust, a byproduct of cement manufacturing, see id. at 6–7,
35–36, and concrete dust from building demolitions, see id. at
34–35. And third, the petitioners pointed to largely anecdotal
evidence about injuries that have been caused by non-aqueous
high-pH substances. See, e.g., id. at 27.

       C. The EPA’s Denial of the Petition for Rulemaking

     The RCRA grants “[a]ny person” the right to “petition the
[EPA] for the promulgation, amendment, or repeal of any
regulation under” the statute. 42 U.S.C. § 6974(a). The EPA’s
regulations provide that the agency “will make a tentative
decision to grant or deny [such] a petition and will publish
notice of such tentative decision, either in the form of an
advanced notice of proposed rulemaking, a proposed rule, or a
tentative determination to deny the petition, in the Federal
Register for written public comment.” 40 C.F.R. § 260.20(c).
Then, “[a]fter evaluating all public comments the [agency] will
make a final decision by publishing in the Federal Register a
regulatory amendment or a denial of the petition.” Id.
§ 260.20(e).
                                10
     Following that procedure, the EPA first tentatively denied
the instant petition for rulemaking. 5 See 81 Fed. Reg. 21,295.
The agency’s Proposed Denial explained that after reviewing
“the petition and its supporting materials, . . . information
submitted by other stakeholders, and relevant information
compiled by the Agency,” the EPA determined that “the
materials submitted in support of the petition fail[ed] to
demonstrate that the requested regulatory revisions [were]
warranted.” Id. at 21,296, 21,299. As required by regulation,
the EPA solicited public comments on the Proposed Denial.
See 40 C.F.R. § 260.20(c). The agency received comments
from PEER, Dr. Jenkins, “a number of groups representing
different sectors of industry, health research groups studying
persons exposed to the World Trade Center (WTC) collapse,
the state of Michigan Department of Environmental Quality
(DEQ), national and state groups representing municipal
wastewater treatment facility owners/operators[,] . . . and
several private citizens.” See Corrosive Waste Rulemaking
Petition; Denial, 86 Fed. Reg. 31,622, 31,624 (June 15, 2021)
(“Final Denial”).

     After reviewing and responding to the comments, the EPA
again “determined that because changes to the existing RCRA
corrosivity characteristic regulation are not supported by the
available information, such changes are unwarranted.” Id. at
31,637. The agency declined to make any revision based on its
misreading of the ILO encyclopedia in the 1980 rulemaking

5
     Because the EPA did not act on the petition for rulemaking for
three years after receiving it, PEER filed a petition for a writ of
mandamus in this court in September 2014. See In re Jenkins, No.
14-1173 (D.C. Cir.) (docketed Sept. 9, 2014). The parties agreed to
hold the case in abeyance when the EPA committed to issuing a
tentative response by a date certain. After the EPA finalized its
denial of the petition for rulemaking, the parties agreed to dismiss
the mandamus action as moot.
                               11
because, it asserted, that source was not the sole basis for
setting the pH 12.5 standard. The EPA explained that it
“considered the ILO guidance as one factor in establishing the
corrosivity regulation, but also considered waste management
practices as part of its determination.” Id. at 31,636.
According to the EPA, the agency “regulated potentially
corrosive wastes under RCRA [§ 6903(5)(B)]” — the statutory
subsection governing wastes that are dangerous if
mismanaged; the ILO guidance, however, “is intended to
represent the inherent, or intrinsic hazards that may be posed
by direct contact with materials, with no controls on or
mitigation of exposure.” Id. at 31,624–25. Because the
“RCRA directs the Agency to regulate hazards as they occur in
waste (when plausibly mismanaged) in most cases,” and the
ILO encyclopedia did not consider the mitigating impact of
waste-management practices, the EPA determined that the ILO
encyclopedia did not compel an upper pH threshold of 11.5.
Id. at 31,625.

     Moreover, the agency reaffirmed its earlier decision to
raise the upper threshold to pH 12.5 in order to allow the
undisturbed use of lime-treated sludges. See id. The agency
relied on the same reasoning it invoked in 1980: “Lime has
been used for many years as a sludge treatment, particularly for
the inactivation of microbial pathogens in the sludge.” Id.
Because this process requires raising “the pH of the sludge . . .
to pH 12 or higher . . . the proposal to revise the corrosivity
regulatory value to 11.5 could have a significant impact on the
implementation of available treatments and management
options for municipal wastewater treatment sludges.” Id. The
protection of the use of lime-treated sludges was entirely
appropriate, according to the agency, because corrosive wastes
are regulated under the “waste management” framework of
§ 6903(5)(B). Id. at 31,627. Under that paradigm, “hazards
are identified and risk is evaluated in the context of waste
                               12
management conditions and practices,” rather than based
“solely on assessment of the intrinsic hazards potentially
corrosive wastes may pose.” Id. Thus, the EPA concluded,
“considering the corrosive potential of wastes treated to high
pH using materials like lime, with its widespread use for
effective . . . sludge pathogen inactivation and stabilization was
and remains an appropriate balancing of different waste
management risks by the Agency.” Id. at 31,625.

       Furthermore, the EPA rejected the proposal to adopt the
lower pH threshold used in the Basel Convention and the GHS.
The agency explained that “[t]he Basel Convention . . . relies
on a narrative definition for identifying corrosive wastes, rather
than directly relying on pH, as the petitioners suggest the U.S[.]
should do.” Id. at 31,627. Moreover, “the United States is not
a party to the Basel Convention.” Id. As for the GHS, the EPA
noted that an above-threshold substance under that system is
only presumptively hazardous, whereas under the RCRA, such
a substance is conclusively hazardous. Id. Moreover, the EPA
emphasized the distinction between “intrinsic[ally]” hazardous
waste under § 6903(5)(A) and waste that is only hazardous if
mismanaged under § 6903(5)(B): “The basis for GHS criteria
is identified as ‘the intrinsic hazard’ of chemicals, and implies
direct exposure. . . . However, EPA’s approach is in most cases
to regulate wastes posing risks when plausibly mismanaged
. . . .” Id.

     The EPA also decided not to revise its requirement that
“corrosive” waste be “aqueous.” The agency rejected the
petitioners’ contention that research on the effects of World
Trade Center dust compelled revisions to the corrosivity
characteristic rule. Although the agency agreed that substantial
research indicates that people exposed to World Trade Center
dust developed respiratory health problems, the variety of
potentially dangerous materials in that dust made it
                               13
“[im]possible to establish a causal connection between the
potential corrosive properties of the dust and the resultant
injuries to those exposed.” Id. at 31,629; see also id. at 31,636.
Additionally, the agency stressed the respiratory nature of the
health problems caused by the World Trade Center dust; such
“injuries, while serious, are not consistent with the gross [skin]
tissue injuries the Agency sought to prevent in regulating some
wastes as hazardous due to their corrosive properties.” Id. at
31,631.

     In addition, the EPA refused to revise the corrosivity
characteristic standard based on the purported dangers of
cement kiln dust or concrete dust. The agency found that
neither type of dust caused “corrosive injury” to people
exposed to them. See id. at 31,633–34. Nor was the agency
persuaded by anecdotal evidence of incidents involving high-
pH and/or non-aqueous materials. The EPA noted that it had
hired a contractor to research potential corrosive injuries that
occurred since the RCRA’s enactment, and of “21 possible
damage incidents” involving corrosive materials identified by
the contractor, “[n]one of the incidents reported worker or other
injuries.” Id. at 31,634. Thus, the scattered anecdotes offered
by the petitioners did not indicate that the existing corrosivity
characteristic regulation — with its pH 12.5 upper threshold
and “aqueous” requirement — was failing to protect health and
the environment. Id.

     PEER (but not Dr. Jenkins) filed the instant petition for
direct review in this court. See 42 U.S.C. § 6976(a)(1).

                  II.     LEGAL STANDARDS

       A. Timeliness

     PEER’s petition for judicial review of agency action
arrives four decades after the EPA promulgated the corrosivity
                                  14
characteristic regulation. Thus, the 90-day time limit for
mounting a direct challenge to that regulation has long since
passed. See 42 U.S.C. § 6976(a)(1). 6 “[O]nce the limitations
period has run,” however, a party might be able to obtain
indirect review of a regulation by “petition[ing] the agency for
amendment or rescission of the regulation[] and then . . .
appeal[ing] the agency’s decision.” NLRB Union v. Fed. Labor
Rels. Auth., 834 F.2d 191, 196 (D.C. Cir. 1987); see also Alon
Refin. Krotz Springs, Inc. v. EPA, 936 F.3d 628, 643 (D.C. Cir.
2019) (per curiam); Pub. Citizen v. NRC, 901 F.2d 147, 152–
53 (D.C. Cir. 1990); Geller v. FCC, 610 F.2d 973, 977–78
(D.C. Cir. 1979) (per curiam); Functional Music, Inc. v. FCC,
274 F.2d 543, 546–47 (D.C. Cir. 1958). Under the NLRB
Union line of cases, a petitioner can sometimes use this
procedure to bring a “claim that a regulation suffers from some
substantive deficiency” after a statutory time limit on direct
challenges to that regulation has elapsed. NLRB Union, 834
F.2d at 196 (emphasis deleted). That is what PEER attempts to
do here.

     But PEER’s ability to circumvent the statutory time limit
for challenging the corrosivity regulation is limited by the
RCRA’s judicial review provision, which mandates that any
petition for review brought after the 90-day deadline must be

6
      “[A] petition for review of action of the [EPA] Administrator in
promulgating any regulation, or requirement under this chapter or
denying any petition for the promulgation, amendment or repeal of
any regulation under this chapter may be filed only in the United
States Court of Appeals for the District of Columbia, and such
petition shall be filed within ninety days from the date of such
promulgation or denial, or after such date if such petition for review
is based solely on grounds arising after such ninetieth day . . . .” 42
U.S.C. § 6976(a)(1) (emphasis added). The 90-day time limit is
jurisdictional. See Edison Elec. Inst. v. EPA, 996 F.2d 326, 331
(D.C. Cir. 1993).
                                15
based “solely on grounds arising after” that deadline. See 42
U.S.C. § 6976(a)(1) (“[A] petition for review . . . shall be filed
within ninety days from the date of such . . . denial, or after
such date if such petition for review is based solely on grounds
arising after such ninetieth day . . . .”). Where Congress has
thus “specifically addressed the consequences of failure to
bring a challenge within the statutory period . . . judicial review
of a petition to repeal or revise rules is time-barred, except to
the extent that the statute allows review based on later-arising
grounds.” Am. Rd. & Transp. Builders Ass’n v. EPA, 588 F.3d
1109, 1113 (D.C. Cir. 2009) (“ARTBA I”) (cleaned up); see
also Nat’l Mining Ass’n v. Dep’t of Interior, 70 F.3d 1345,
1350–51 (D.C. Cir. 1995). Accordingly, once the 90-day
deadline expires, “a substantive attack on a regulation as
originally promulgated” must be based on grounds that arose
after that ninetieth day. See Alon Refin., 936 F.3d at 644.

     By contrast, a petitioner may “seek [a] rule revision based
on post-rulemaking events” that “have fatally undermined the
original justification for the rule.” Id. at 645. Such a challenge,
however, does not permit review of “defects extant at the time
of the [original] rulemaking.” Id.

     There is another way to avoid the restrictions posed by the
90-day deadline to challenge a regulation under the RCRA: A
petitioner can establish that the agency reopened the
administrative proceedings. Reopening is an “exception to
statutory limits on the time for seeking review of an agency
decision.” Nat’l Ass’n of Reversionary Prop. Owners v.
Surface Transp. Bd., 158 F.3d 135, 141 (D.C. Cir. 1998)
(cleaned up). “The general principle is that if the agency has
opened the issue up anew, even though not explicitly, its
renewed adherence is substantively reviewable.” Pub. Citizen,
901 F.2d at 150 (cleaned up). In determining whether a
reopening has occurred, the ultimate question is whether the
                                16
“entire context” of the proceeding, “includ[ing] all relevant
proposals and reactions of the agency,” indicates “that the
agency has undertaken a serious, substantive reconsideration of
the existing rule.” Growth Energy v. EPA, 5 F.4th 1, 21 (D.C.
Cir. 2021) (per curiam) (cleaned up). If the agency reopens an
issue, but ultimately decides to retain the prior rule, the
reopening causes the period for judicial review “to run anew.”
Ohio v. EPA, 838 F.2d 1325, 1328 (D.C. Cir. 1988). As the
petitioner, PEER bears the burden of demonstrating that the
EPA’s “intention to initiate a reopening [is] . . . clear from the
administrative record.” Biggerstaff v. FCC, 511 F.3d 178, 185
(D.C. Cir. 2007); cf. Sendra Corp. v. Magaw, 111 F.3d 162,
167 (D.C. Cir. 1997) (“[U]nless the agency clearly states or
indicates that it has reopened the matter, its refusal of a request
for reconsideration will be treated as simply that.”).

     To summarize, a petitioner like PEER that seeks review of
a RCRA regulation must do so within ninety days of the
regulation’s promulgation, unless that petitioner instead
petitions to repeal or amend the regulation, in which case it may
seek review of a denial of that petition — provided that the
petition relies on grounds “arising after” the original 90-day
time limit elapsed. Alternatively, the petitioner may achieve
review of a regulation after the 90-day limit expires by
establishing that the agency reopened the administrative
proceedings, in which case the petitioner’s claims need not rely
on grounds “arising after” the 90-day period. Such procedures
are distinct from those that govern petitions to repeal or amend
a regulation based on post-rulemaking events that have since
undermined the rule, but do not indicate that the regulation was
wrong when it was promulgated.

    This thicket of timeliness rules and exceptions serves “the
important purpose of imparting finality into the administrative
process, thereby conserving administrative resources.” Eagle-
                              17
Picher Indus., Inc. v. EPA, 759 F.2d 905, 911 (D.C. Cir. 1985)
(cleaned up). Furthermore, statutory time limits “protect[] the
reliance interests of regulatees who conform their conduct to
the regulations.” Nat. Res. Def. Council v. NRC, 666 F.2d 595,
602 (D.C. Cir. 1981). Although judicial review often serves a
crucial role in ensuring the rationality of agency
decisionmaking, jurisdictional time limits on such review
“reflect a deliberate congressional choice to impose statutory
finality on agency orders, a choice we may not second-guess.”
Eagle-Picher Indus., 759 F.2d at 911 (cleaned up).

       B. Review of Merits

     If PEER demonstrates that its challenge is timely, we may
review the EPA’s decision not to revise the corrosivity
characteristic regulation. See Massachusetts v. EPA, 549 U.S.
497, 527–28 (2007) (holding that denials of petitions for
rulemaking are judicially reviewable). But our review of a
denial of a petition for rulemaking is “‘extremely limited’ and
‘highly deferential’.” Id. (quoting Nat’l Customs Brokers &
Forwarders Ass’n of Am., Inc. v. United States, 883 F.2d 93,
96 (D.C. Cir. 1989)); accord McAfee v. FDA, 36 F.4th 272, 274
(D.C. Cir. 2022); Flyers Rights Educ. Fund, Inc. v. FAA, 864
F.3d 738, 743 (D.C. Cir. 2017); WildEarth Guardians v. EPA,
751 F.3d 649, 653 (D.C. Cir. 2014). Indeed, we have stated
that “review of an agency’s denial of a rulemaking ‘is evaluated
with a deference so broad as to make the process akin to
nonreviewability.’” Verizon v. FCC, 770 F.3d 961, 966 (D.C.
Cir. 2014) (quoting Cellnet Commc’n, Inc. v. FCC, 965 F.2d
1106, 1111 (D.C. Cir. 1992)). Accordingly, “we may reverse
the agency’s choice ‘only for compelling cause, such as plain
error of law or a fundamental change in the factual premises
previously considered by the agency.’” McAfee, 36 F.4th at
274 (quoting Nat’l Customs Brokers, 883 F.2d at 97).
                              18
                      III.    ANALYSIS

       A. Standing

     The EPA does not challenge PEER’s Article III standing.
But “we have an independent obligation to assure ourselves
that standing exists.” Belmont Mun. Light Dep’t v. FERC, 38
F.4th 173, 185 (D.C. Cir. 2022) (cleaned up). PEER brings this
suit on behalf of its members. It therefore must demonstrate
that “its members would otherwise have standing to sue in their
own right, the interests at stake are germane to the
organization’s purpose, and neither the claim asserted nor the
relief requested requires the participation of individual
members in the lawsuit.” Friends of the Earth, Inc. v. Laidlaw
Env’t Servs. (TOC), Inc., 528 U.S. 167, 181 (2000) (citing Hunt
v. Wash. State Apple Advert. Comm’n, 432 U.S. 333, 343
(1977)). Declarations from PEER members establish that they
have standing to sue in their own right because they live near
or work with wastes that would be regulated as “corrosive” if
the petition for rulemaking were granted. Compare PEER
Addendum at 42–50 (members’ declarations), with Nat. Res.
Def. Council v. EPA, 755 F.3d 1010, 1016–18 (D.C. Cir. 2014)
(holding comparable declarations sufficient to establish
representational standing). Next, “the interests at stake” are
plainly “germane,” Laidlaw, 528 U.S. at 181, to PEER’s
purpose of “protect[ing] the environment, public health, and
the health of its members from environmental hazards
including from improper disposal of dangerous wastes.” PEER
Br. 10. Moreover, “there is no question . . . that the relief
requested — a rulemaking — does not require participation by
individual members” of PEER. Flyers Rights Educ. Fund, Inc.
v. Dep’t of Transp., 957 F.3d 1359, 1362 (D.C. Cir. 2020). We
are thus satisfied that PEER has standing to bring this appeal.
                                 19
        B. Time-Barred Claims

      PEER asserts that when the EPA promulgated the
corrosivity regulation in 1980, the agency acted arbitrarily,
capriciously, and not in accordance with law by misreading the
ILO encyclopedia and improperly seeking to accommodate the
commercial use of lime-treated waste sludges. Before we can
reach the merits of these claims, we must address their timing.
PEER has missed — by more than four decades — the 90-day
deadline to file a direct challenge to the regulation. See 42
U.S.C. § 6976(a)(1). Although PEER more recently filed a
petition to amend the regulation and seeks review of the denial
of that petition, the claims related to the ILO encyclopedia and
lime-treated sludges did not “arise after” the 90-day deadline
expired – i.e., they could have been brought when the rule was
first promulgated. See supra Part II.A. Therefore, the only
way that PEER can establish the timeliness of these claims —
and thus our jurisdiction, see Edison Elec. Inst., 996 F.2d at 331
— is to demonstrate that the EPA reopened the administrative
proceedings on corrosivity when it responded to PEER’s
petition for rulemaking. 7

7
      PEER arguably forfeited its argument that the EPA reopened
the proceedings by raising that claim only in “an oblique footnote”
in its opening brief. CTS Corp. v. EPA, 759 F.3d 52, 60 (D.C. Cir.
2014); see also PEER Br. 16–17 n.1 (“Questions about the original
decision’s consistency with congressional intent are not time-barred
where the agency has in effect re-adopted the earlier decision in the
new decision.”); Scenic Am., Inc. v. Dep’t of Transp., 836 F.3d 42,
53 n.4 (D.C. Cir. 2016) (“Although a party cannot forfeit a claim that
we lack jurisdiction, it can forfeit a claim that we possess
jurisdiction.”). The EPA, however, does not argue that PEER
forfeited the issue. See EPA Br. 22–26 (addressing merits of
reopening issue). Thus, “[b]y failing to argue forfeiture . . . the
[EPA] has — in a word — forfeited [its] forfeiture argument here.”
Solomon v. Vilsack, 763 F.3d 1, 13 (D.C. Cir. 2014); see also Me.
                               20
     PEER asserts that the EPA did reopen the matter. See
PEER Reply Br. 9–14. According to PEER, the agency
undertook “a serious, substantive reconsideration of the
existing rule,” Growth Energy, 5 F.4th at 21 (cleaned up), by
responding to comments about the petition for rulemaking,
reviewing the evidence submitted by the petitioners, and
conducting its own research on the issues raised. But PEER
overlooks that the agency was required to analyze and respond
to PEER’s petition and any attendant comments. See 42 U.S.C.
§ 6974(a)–(b)(1); 40 C.F.R. § 260.20(c), (e). PEER cites no
cases, and we are aware of none, in which an agency reopened
an issue by merely responding to a petition for rulemaking
submitted by a third party. See Am. Rd. & Transp. Builders
Ass’n v. EPA, 705 F.3d 453, 457 (D.C. Cir. 2013) (“ARTBA
II”) (“[A]n agency’s response to a petitioner’s comments
cannot provide the sole basis for reopening.”); ARTBA I, 588
F.3d at 1114 (“We rarely if ever find such a response [to a
petition for rulemaking] sufficient [to find reopening].”); Nat’l
Mining Ass’n, 70 F.3d at 1352 (“Of course, that a statement
accompanies the denial of a petition for rulemaking is not,
without much more, sufficient to trigger the reopener
doctrine.”); cf. Kennecott Utah Copper Corp. v. Dep’t of
Interior, 88 F.3d 1191, 1213 (D.C. Cir. 1996) (“[W]hen the
agency merely responds to an unsolicited comment by
reaffirming its prior position, that response does not create a
new opportunity for review.”); see generally Ronald M. Levin,
Statutory Time Limits on Judicial Review of Rules: Verkuil
Revisited, 32 Cardozo L. Rev. 2203, 2224–25 (2011) (“One
can, of course, ask the agency to reexamine its [time-barred]
rule; if it voluntarily does so, a new rulemaking proceeding will
commence, with its own judicial review deadlines. But the
courts have not allowed litigants to use this device as a

Lobstermen’s Ass’n v. Nat’l Marine Fisheries Serv., 70 F.4th 582,
594 (D.C. Cir. 2023).
                              21
disguised method of circumventing the time limitation on
review of the extant rule.”). Indeed, we have emphasized that
a petitioner may not “goad an agency into a reply, and then sue
on the grounds that the agency ha[s] re-opened the issue,”
noting that such a rule “would undermine congressional efforts
to secure prompt and final review of agency decisions.” Am.
Iron & Steel Inst. v. EPA, 886 F.2d 390, 398 (D.C. Cir. 1989).

     Our decisions that have found a reopening of the
administrative process further illustrate the point. They
generally fall into three categories (which are not necessarily
exclusive and in some cases may overlap). The first and most
prominent category involves cases where an agency decides on
its own initiative to invite public comment on a prior decision,
generally by issuing a notice of proposed rulemaking or a
similar invitation for public feedback. See, e.g., Appalachian
Power Co. v. EPA, 251 F.3d 1026, 1032–33 (D.C. Cir. 2001);
PanAmSat Corp. v. FCC, 198 F.3d 890, 897 (D.C. Cir. 1999);
Edison Elec. Inst., 996 F.2d at 331–32; Ass’n of Am. R.Rs. v.
ICC, 846 F.2d 1465, 1473 (D.C. Cir. 1988); Ohio, 838 F.2d at
1328–29; Montana v. Clark, 749 F.2d 740, 743–44 (D.C. Cir.
1984). Second, we have noted that an agency indicates a
reopening by constructing a new rationale for an old policy.
See, e.g., CTIA-Wireless Ass’n v. FCC, 466 F.3d 105, 110–12
(D.C. Cir. 2006); Bluewater Network v. EPA, 370 F.3d 1, 16–
17 (D.C. Cir. 2004). Third, we have held that an agency may
reopen an existing policy by deciding to make it permanent,
such as by reevaluating and readopting on a prospective basis
a previously interim decision, see, e.g., Pub. Citizen, 901 F.2d
at 151, or by withdrawing proposed changes to the agency’s
approach, see, e.g., Env’t Def. Fund v. EPA, 852 F.2d 1316,
1324–25 (D.C. Cir. 1988). All three categories illustrate that a
voluntary and affirmative agency action — rather than a
required or reactive one — is the hallmark of a reopening. See
Ohio, 838 F.2d at 1328 (“[T]he period for seeking judicial
                               22
review may be made to run anew when the agency in question
by some new promulgation creates the opportunity for renewed
comment and objection.” (emphasis added)); see also Gen.
Motors Corp. v. EPA, 363 F.3d 442, 450 (“A ‘promulgation’
[in the reopening context] involves more formal agency action
. . . .”).

     While an agency could conceivably reopen an
administrative proceeding in response to a petition for
rulemaking, the party challenging the denial of such a petition
must show that the agency’s “intention to initiate a reopening”
is “clear from the administrative record.” Biggerstaff, 511 F.3d
at 185. That requires showing that the agency did “much more”
than merely take legally required steps to respond to the
petition for rulemaking. Nat’l Mining Ass’n, 70 F.3d at 1352
(“Of course, that a statement accompanies the denial of a
petition for rulemaking is not, without much more, sufficient to
trigger the reopener doctrine.”). The agency’s intent to reopen
must be crystal clear in this context because we are reluctant to
create conflicting incentives for the agency, which is duty-
bound to provide a careful response to a petition for
rulemaking, yet might be reluctant to do so if a detailed review
would be interpreted as a reopening of the administrative
process. See ARTBA I, 588 F.3d at 1114 (declining to hold that
an “agency’s thorough answer would put it at risk of
‘reopening,’ while a taciturn response would put it at risk of
being faulted for acting without reasoned decisionmaking”).
We also are mindful that statutory time limits reflect
Congress’s express preference for regulatory finality. See
Eagle-Picher Indus., 759 F.2d at 911; Nat. Res. Def. Council,
666 F.2d at 602. That congressional goal would be frustrated
by applying a lenient standard for revisiting decisions that
already have undergone a full rulemaking procedure.
                              23
      Here, we conclude that PEER has not met its burden to
prove that the EPA reopened the process for regulating
corrosivity. This is not a case in which the agency itself, “by
some new promulgation[,] create[d] the opportunity for
renewed comment and objection.” Ohio, 838 F.2d at 1328.
Rather, PEER and Dr. Jenkins petitioned the agency to change
its rule. We discern no evidence from the administrative record
that the EPA intended to initiate a reopening of the
administrative process in response to the petition. Rather, the
EPA merely followed the legally prescribed process for
responding to the petition. The agency (1) examined the
petition and the evidence submitted by the petitioners, see 42
U.S.C. § 6974(a); 40 C.F.R. § 260.20(c); (2) published its
Proposed Denial and solicited public comment, see 42 U.S.C.
§ 6974(b)(1); 40 C.F.R. § 260.20(c); 81 Fed. Reg. 21,295;
(3) reviewed and responded to comments on the Proposed
Denial, see 40 C.F.R. § 260.20(e); 86 Fed. Reg. at 31,624
(noting that the EPA responded to “29 comments on the
tentative denial” before finalizing its decision); RTC Doc.; and
(4) published its final denial of the petition, see 42 U.S.C.
§ 6974(a); 40 C.F.R. § 260.20(e); 86 Fed. Reg. 31,622. The
agency did not do “much more” than what was required by law
and did not betray any intent to reopen the 1980 rulemaking.
Nat’l Mining Ass’n, 70 F.3d at 1352. To the contrary, the EPA
specifically stated that it was too late to revisit the original
rulemaking, and thereby indicated that the agency was not
going down that road. See 86 Fed. Reg. at 31,625 (“[N]o
challenge to the 1980 regulation was filed, and the time period
to challenge that rule has long passed . . . .”).

     Nevertheless, PEER argues that the EPA reopened the
corrosivity characteristic rulemaking by offering a new
rationale for the upper pH level when it denied the petition to
amend the regulation. According to PEER, the agency stated,
for the first time, that it relied on waste-management
                                  24
considerations under § 6903(5)(B) in setting the upper
corrosivity threshold at pH 12.5. See PEER Reply Br. 3–5.
Offering new reasons to support a pre-existing policy is a factor
that weighs in favor of finding reopening. 8 See CTIA-Wireless
Ass’n, 466 F.3d at 112. But on closer inspection, this
purportedly “new” rationale is anything but. The first page of
the 1980 background document on the corrosivity
characteristic regulation plainly refers to waste-management
considerations, in words drawn from the § 6903(5)(B)
standard, when discussing the agency’s determination of how
to define “corrosiveness.” Compare 42 U.S.C. § 6903(5)
(defining “hazardous waste” to mean “a solid waste” that may
“(B) pose a substantial present or potential hazard to human
health or the environment when improperly treated, stored,
transported, or disposed of, or otherwise managed”), with 1980
Background Doc. at 1 (“The Agency has determined that
corrosiveness . . . is a hazardous characteristic because
improperly managed corrosive wastes pose a substantial
present or potential danger to human health and the
environment.”). 9

8
      PEER also points out that in the Final Denial, the EPA made no
mention of its former position that the ILO encyclopedia’s pH 11.5
standard is based on eye tissue. See PEER Reply Br. 13. True, but
it is a new rationale that weighs in favor of finding reopening, not
merely a failure to reiterate an old reason. See CTIA-Wireless Ass’n,
466 F.3d at 112.
9
      To be sure, the EPA explained the connection between
§ 6903(5)(B) and the corrosivity characteristic rule more clearly in
2021 than it did in 1980. But “[a]s long as ‘the agency’s path may
reasonably be discerned,’ we will uphold the decision even if it is ‘of
less than ideal clarity.’” Casino Airlines, Inc. v. NTSB, 439 F.3d 715,
717 (D.C. Cir. 2006) (quoting Bowman Transp., Inc. v. Ark.-Best
Freight Sys., Inc., 419 U.S. 281, 285–86 (1974)).
                               25
     PEER also notes that the agency “hired a consultant to
develop a report on environmental damage cases or incidents
potentially caused by corrosive waste mismanagement ‘that
have occurred since the corrosivity regulation was
established.’” PEER Reply Br. 12 (quoting 86 Fed. Reg. at
31,634) (emphasis deleted).         In some cases, investing
significant resources in determining whether existing standards
adequately protect human health and the environment might
indicate an agency’s “serious, substantive reconsideration of
the existing rule.” Growth Energy, 5 F.4th at 21 (cleaned up).
But here, the EPA “appears merely to have” hired a consultant
to identify any post-rulemaking incidents “on the premise that
they might have persuaded [the agency] to actually reopen the
matter.” ARTBA I, 588 F.3d at 1115. When the consultant
failed to uncover evidence to justify reopening the 1980
rulemaking, the agency decided not to embark on such an
effort. Where, as here, the “entire context” of the proceeding,
“includ[ing] all relevant proposals and reactions of the
agency,” Growth Energy, 5 F.4th at 21 (cleaned up), reveals no
serious agency hesitation about the continued propriety of the
regulation in question, we decline to find “that the EPA
reopened the[] standards in spite of the agency’s explicit efforts
not to do so.” Safe Food & Fertilizer v. EPA, 350 F.3d 1263,
1267 (D.C. Cir. 2003).

     In sum, PEER fails to meet its burden to show the agency’s
“clear” intent to reopen the administrative proceeding.
Biggerstaff, 511 F.3d at 185. The agency did not do “much
more” than comply with legal directives to consider and
respond to PEER’s petition for rulemaking. Nat’l Mining
Ass’n, 70 F.3d at 1352. Accordingly, PEER’s claims regarding
the ILO encyclopedia and lime-treated sludge are untimely and
we lack jurisdiction to consider them.
                                 26
        C. Other Claims

     PEER’s remaining claims “seek [a] rule revision based on
post-rulemaking events” that it asserts “have fatally
undermined the original justification for the rule.” Alon Refin.,
936 F.3d at 645; see also supra Part II.A. PEER contends that
new evidence supports amending the corrosivity characteristic
regulation by lowering the upper pH threshold and removing
the requirement of “aqueousness.”              PEER cites the
international pH standards adopted by the Basel Convention
and the GHS, which did not exist in 1980. See PEER Br. 35–
37. Moreover, PEER bases its argument that the “aqueous”
requirement should be amended on evidence from the World
Trade Center attack of September 11, 2001, and a handful of
other incidents, the earliest of which appears to date from 1982.
See PEER Br. 46–50 (discussing dust from the World Trade
Center attack); id. at 52 (discussing 1982 incident at the
Kearsarge Metallurgical Corporation site in New Hampshire).

     Although these claims are timely and properly before us,
our review of them is “highly deferential.” Massachusetts, 549
U.S. at 528 (cleaned up). To prevail, PEER must demonstrate
a “compelling cause” to disturb the agency’s decision, “such as
[a] plain error of law or a fundamental change in the factual
premises previously considered by the agency.” McAfee, 36
F.4th at 274 (cleaned up). 10

10
     PEER also argues that the EPA impermissibly considered the
economic costs of its proposed revisions, based on industry cost
estimates submitted in response to the Proposed Denial. See PEER
Br. 26–27; see also Util. Solid Waste Activities Grp. v. EPA, 901 F.3d
414, 448–49 (D.C. Cir. 2018) (per curiam). But we defer to the
agency’s contrary statement in the Final Denial that its decision to
maintain the corrosivity characteristic regulation was “not based on
                               27
           1. International Standards for Corrosivity

     PEER argues that the EPA should have revised the
corrosivity characteristic regulation to match the Basel
Convention and the GHS, international standards that use pH
11.5 as a threshold. See PEER Br. 35–37. The EPA declined
to align the corrosivity characteristic regulation with those
international standards essentially because the pH thresholds
are used differently in the Basel Convention and the GHS than
in the corrosivity characteristic regulation.       Under the
international standards, substances with an above-threshold pH
are not necessarily deemed hazardous, as wastes with a pH
greater than 12.5 are under the corrosivity characteristic. See
86 Fed. Reg. at 31,627. Moreover, the United States is bound
by neither the Basel Convention, to which it is not a party, nor
the GHS, which is voluntary. Id. Under our “extremely limited
and highly deferential” standard of review, Massachusetts, 549
U.S. at 527–28 (cleaned up), we cannot say that this reasoning
is so wrong as to constitute “compelling cause” to reverse the
agency’s decision, McAfee, 36 F.4th at 274 (cleaned up).

           2.   Non-Aqueous Wastes

     Petitioners claim that non-aqueous high-pH substances
can cause serious health effects and therefore should be
considered corrosive. They cite as examples dust generated by
the World Trade Center attack and cement kiln dust, which
they claim have caused injuries to the respiratory systems of
those affected. They also rely on anecdotal evidence of
incidents where non-aqueous high-pH substances were
mismanaged.

the potential economic impacts of the petitioners’ proposals.” 86
Fed. Reg. at 31,633.
                                 28
     We defer to the EPA’s conclusion that the World Trade
Center evidence does not support reconsideration of the
“aqueous” requirement because, given the variety of
potentially harmful substances present in the aftermath of the
9/11 attacks, “it is not possible to establish a causal connection
between the potential corrosive properties of the dust and the
resultant injuries to those exposed.” 86 Fed. Reg. at 31,629.11
The EPA also permissibly found that the respiratory effects of
the World Trade Center dust, “while serious, are not consistent
with the gross tissue injuries the Agency sought to prevent”
when it established the corrosivity characteristic regulation. Id.
at 31,631. Even if there are grounds to disagree with that
reasoning, the agency’s decision does not reflect the kind of
“plain error of law” that would justify remanding the issue.
McAfee, 36 F.4th at 274 (cleaned up).

     We also uphold the agency’s rejection of PEER’s
proffered evidence “that cement kiln dust, with a pH of 10–13,
causes severe burns and is harmful by inhalation.” PEER Br.
39–40 (cleaned up). The EPA noted that it “has separately
assessed the hazards of [cement kiln dust], and despite its high
pH (pH 10–13), did not find corrosive injury to potentially
exposed workers.” 86 Fed. Reg. at 31,633. The agency also
cited studies postdating the agency’s prior assessment of
cement kiln dust, which similarly did not find “corrosive
injuries in [the] exposed worker populations.”                Id.
“[B]alancing conflicting evidence is the agency’s job, not ours,
as long as the agency reasonably weighs evidence both

11
      To the extent that PEER also relies on its World Trade Center
evidence to advocate lowering the pH threshold, see PEER Br. 39–
40 (describing various studies of World Trade Center dust as
“extensive evidence of harm from pH 11.5 to 12.5 alkaline wastes”),
the EPA’s reasoning that the effects of the dust cannot necessarily be
attributed to the dust’s “corrosive” nature also supports the agency’s
decision not to adopt the pH 11.5 threshold.
                               29
supporting and undermining its final conclusion.” Advocs. for
Highway & Auto Safety v. Fed. Motor Carrier Safety Admin.,
41 F.4th 586, 607 (D.C. Cir. 2022). Applying our “highly
deferential” standard of review, Massachusetts, 549 U.S. at 528
(cleaned up), we decline to upset the EPA’s weighing of this
evidence.

     Finally, the EPA acted within its discretion when it
declined to regulate based on anecdotal evidence, after
articulating reasonable grounds for discounting that evidence.
See 86 Fed. Reg. at 31,627 (“The Agency did in fact review
and consider the supporting material submitted with the
petition as well as the petition itself and the relevant documents
cited in petition footnotes . . . [and] concluded that aspects of
the supporting material submitted were not relevant . . . while
other material was anecdotal or focused on illustrating the
intrinsic hazards of some alkaline materials.”); id. at 31,634
(rejecting evidence of cases of mismanagement of purportedly
corrosive materials because they did not involve “reported
worker or other injuries either before or during remediation”);
81 Fed. Reg. at 21,307 (determining that incident involving a
dangerous substance that did not meet technical standards for
“aqueous” waste supported “clarifying the Agency’s approach
to determining what wastes are aqueous,” rather than changing
the corrosivity characteristic regulation).

                     IV.     CONCLUSION

     For the foregoing reasons, we deny the petition for review.
PEER’s arguments concerning the EPA’s erroneous
understanding of the ILO encyclopedia analysis and its
allegedly improper protection of the commercial use of lime-
treated sludge are untimely; we therefore lack jurisdiction to
consider them. Moreover, we are required to apply a highly
deferential standard of review with respect to PEER’s
                           30
remaining claims and find no basis to disturb the agency’s
decisions.

                                               So ordered.