24-1193 | Omnilex

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United States Court of Appeals
FOR THE DISTRICT OF COLUMBIA CIRCUIT

Argued January 20, 2026 Decided August 18, 2026

No. 24-1193

C
HAMBER OF COMMERCE OF THE UNITED STATES OF
AMERICA, ET AL.,
PETITIONERS

E
NVIRONMENTAL PROTECTION AGENCY AND LEE M. ZELDIN,
IN HIS OFFICIAL CAPACITY AS
ADMINISTRATOR, UNITED
STATES ENVIRONMENTAL PROTECTION AGENCY,
R
ESPONDENTS

CLEAN CAPE FEAR, ET AL.,
INTERVENORS

Consolidated with Nos. 24-1261, 24-1266, 24-1271, 24-1272

On Petitions for Review of a Final Rule
of the Environmental Protection Agency

Elbert Lin argued the cause for petitioners. With him on
the briefs were Andrew R. Varcoe, Stephanie A. Maloney, Paul
T. Nyffeler, David M. Parker, Matthew Z. Leopold, Christopher

L. Bell, Susan Parker Bodine, Richard S. Moskowitz, and Tyler
Kubik. Brittany M. Pemberton entered an appearance.

Michael B. Kimberly and Michael A. Tilghman II were on
the brief for amici curiae National Association of
Manufacturers and Printing United Alliance in support of
petitioners. Nicole E. Wittstein entered an appearance.

Douglas A. Hastings and Mark Donatiello were on the
brief for amicus curiae Superfund Settlements Project in
support of petitioners.

Erica Spitzig, Aaron M. Herzig, Anne M. McClellan, and
David C. Roper were on the brief for amicus curiae Passive
Receivers in support of remand.

Riley W. Walters, Counsel to the Assistant Attorney
General, U.S. Department of Justice, argued the cause for
respondents. On the brief were Adam R.F. Gustafson, Principal
Deputy Assistant Attorney General, and Jin Hyung Lee,
Attorney, and Elizabeth G. Berg and Noel M. Johnson,
Attorneys, U.S. Environmental Protection Agency.

Jonathan Kalmuss-Katz argued the cause for intervenors
Clean Cape Fear, et al. in support of respondents. With him on
the brief were Lillian Zhou and Alana R. Reynolds.

Letitia James, Attorney General for the State of New York,
Barbara D. Underwood, Solicitor General, Judith Vale,
Deputy Solicitor General, Joshua N. Cohen, Assistant Solicitor
General, Philip M. Bein, Senior Counsel, Kyle Burns, Assistant
Attorney General, Mihir Desai, Assistant Attorney General,
Kristin K. Mayes, Attorney General for the State of Arizona,
Philip J. Weiser, Attorney General for the State of Colorado,
William Tong, Attorney General for the State of Connecticut,

Brian L. Schwalb, Attorney General for the District of
Columbia, Kwame Raoul, Attorney General for the State of
Illinois, Anthony G. Brown, Attorney General for the State of
Maryland, Andrea J. Campbell, Attorney General for the
Commonwealth of Massachusetts, Dana Nessel, Attorney
General for the State of Michigan, Keith Ellison, Attorney
General for the State of Minnesota, Matthew J. Platkin,
Attorney General for the State of New Jersey, Raúl Torrez,
Attorney General for the State of New Mexico, Dan Rayfield,
Attorney General for the State of Oregon, Nicholas W. Brown,
Attorney General for the State of Washington, and Josh Kaul,
Attorney General for the State of Wisconsin, were on the brief
for amici curiae States of New York, et al. in support of
respondents.

Before: M
ILLETT, KATSAS, and RAO, Circuit Judges.

Opinion for the Court filed by Circuit Judge MILLETT.

M
ILLETT, Circuit Judge: Perfluorooctanoic Acid
(“PFOA”) and Perfluorooctanesulfonic Acid (“PFOS”) are two
compounds in a large group of human-made substances
commonly referred to as “forever chemicals.” In 2024, the
Environmental Protection Agency designated PFOA and PFOS
as “hazardous substances” under the Comprehensive
Environmental Response, Compensation, and Liability Act of
1980. EPA based its determination on extensive studies that
link PFOA and PFOS exposure to serious health conditions in
humans, including cancer and developmental delays.

Seven interest groups representing industries that use,
transport, or discharge PFOA and PFOS petitioned this court
to overturn EPA’s decision. We deny those petitions.

Congress enacted the Comprehensive Environmental
Response, Compensation, and Liability Act, Pub. L. No. 96-
510, 94 Stat. 2767, in 1980, and added to that regime in 1986
with the Superfund Amendments and Reauthorization Act of
1986, Pub. L. No. 99-499, 100 Stat. 1613, now codified
together at 42 U.S.C. § 9601 et seq. (“CERCLA”). CERCLA
governs the cleanup of “hazardous substances” and “pollutants
or contaminants” from the environment. 42 U.S.C. §§ 9604,
9606. The Act was Congress’s response to a series of high-
profile toxic chemical releases, including the infamous dump
of thousands of tons of chemicals in Love Canal, New York
that led to birth defects, miscarriages, and a devastated
community. See S.
REP. NO. 848, 96th Cong., 2d Sess. 4–5, 8–
10 (1980); see also Niagara Mohawk Power Corp. v. Chevron
U.S.A., Inc., 596 F.3d 112, 120 & n.5 (2d Cir. 2010).

CERCLA classifies as a “hazardous substance” those
substances listed in or designated under other environmental
laws, like the Clean Water Act. There are currently over 800
such hazardous substances. 42 U.S.C. § 9601(14); 40 C.F.R.
§ 302.4 table (enumerating those substances). CERCLA also
authorizes EPA to designate as additional “hazardous
substances” those “elements, compounds, mixtures, solutions,
and substances” that, “when released into the environment[,]
may present substantial danger to the public health or welfare
or the environment[.]” 42 U.S.C. § 9602(a).

CERCLA both encourages “timely cleanup” of harmful
chemical releases and hazardous waste sites and “ensure[s] that
the costs” of cleanups are “borne by those responsible” for the
pollution. Atlantic Richfield Co. v. Christian, 140 S. Ct. 1335,

1345 (2020) (quoting CTS Corp. v. Waldburger, 573 U.S. 1, 4
(2014)).

CERCLA provides for two kinds of cleanups: (1) removal
actions and (2) remedial actions. 42 U.S.C. § 9601(23), (24),
(25). Removal actions are short-term measures aimed at
promptly preventing or mitigating a release of dangerous
chemicals. J.A. 447–448.

Remedial actions, on the other hand, are longer-term
efforts involving “a complex, multi-phase process” aimed at
“significantly reduc[ing] serious but not immediately life-
threatening risks” from chemical releases. J.A. 447; see 42
U.S.C. § 9601(24). Remedial actions are generally conducted
at locations listed on the “National Priorities List,” a statutorily
mandated list of sites across the country that present the
greatest danger to public health. 42 U.S.C. § 9605(a)(8)(A)–
(B); Linemaster Switch Corp. v. EPA, 938 F.2d 1299, 1301
(D.C. Cir. 1991). They are commonly known as “Superfund
sites[.]” Atlantic Richfield Co., 140 S. Ct. at 1346.

Cleanups can proceed along two statutory pathways. First,
“Section 106” cleanups are triggered only by the release of a
“hazardous substance[.]” 42 U.S.C. § 9606(a). For these
cleanups, EPA may compel responsible parties to undertake the
cleanup in the first instance. Id.

Second, “Section 104” cleanups can be triggered by the
release of either (1) a “hazardous substance” or (2) a “pollutant
or contaminant” if it “may present an imminent and substantial
danger to the public health or welfare[.]” 42 U.S.C.
§ 9604(a)(1). A “pollutant or contaminant” is defined as
including:

[A]ny element, substance, compound, or mixture,
including disease-causing agents, which after release
into the environment and upon exposure, ingestion,
inhalation, or assimilation into any organism, either
directly from the environment or indirectly by
ingestion through food chains, will or may reasonably
be anticipated to cause death, disease, behavioral
abnormalities, cancer, genetic mutation, physiological
malfunctions (including malfunctions in
reproduction) or physical deformations, in such
organisms or their offspring[.]

42 U.S.C. § 9601(33).

Within Section 104 cleanups, who foots the bill depends
on what needs cleaning up. When EPA leads the cleanup of
hazardous substances, the responsible polluters can later be
made to cover the costs through cost-recovery actions, so long
as the cleanups were “not inconsistent with the national
contingency plan[.]” 42 U.S.C. § 9607(a); Cooper Indus., Inc.
v. Aviall Servs., Inc., 543 U.S. 157, 161 (2004). The National
Contingency Plan, in turn, is a series of statutorily required
regulations that prescribe the methods and scope of Section 104
cleanups. 42 U.S.C. § 9605; 40 C.F.R. pt. 300.

Such refund actions are not possible for releases of
pollutants or contaminants, however. See 42 U.S.C. § 9607(a).
That means that Section 104 cleanups of pollutants or
contaminants are paid for entirely by public funds, either
(1) through the Superfund, which Congress set up to pay for
major CERCLA cleanup efforts, 42 U.S.C. § 9611(a); Ohio v.
Department of the Interior, 880 F.2d 432, 439 (D.C. Cir. 1989),
or (2) through appropriations by Congress, see G
OVERNMENT
ACCOUNTABILITY OFF., GAO-15-812, SUPERFUND: TRENDS IN

FEDERAL FUNDING AND CLEANUP OF EPA’S NONFEDERAL
NATIONAL PRIORITIES LIST SITES 12 (2015).

Perfluoroalkyl and Polyfluoroalkyl Substances (“PFAS”)
is the scientific name for a broad category of human-made
chemicals. Designation of Perfluorooctanoic Acid (PFOA)
and Perfluorooctanesulfonic Acid (PFOS) as CERCLA
Hazardous Substances, 89 Fed. Reg. 39,124, 39,125 (May 8,
2024) (“Designation”). They have been used in the United
States since the 1940s to create water- and oil-resistant
products like cookware, rain-repellent clothing, and
firefighting foam. Id. at 39,126.

PFAS take hundreds of years to degrade in the
environment and take decades to be eliminated from human
bodies, earning them the title “forever chemicals[.]”
Designation, 89 Fed. Reg. at 39,126 (quotation marks omitted).
PFAS have also been linked to many adverse health effects,
including cancer, developmental effects in children, and
cardiovascular conditions. See id. at 39,145–39,146.

EPA has historically regulated two of the most common
PFAS—PFOA and PFOS—as “pollutants or contaminants”
under CERCLA. Designation, 89 Fed. Reg. at 39,153.

Several years ago, as scientific evidence of the harms
posed by PFOA and PFOS accumulated, EPA began
considering whether to designate the two chemicals as
“hazardous substances” under CERCLA. In studying the issue,
EPA published in August 2022 an Economic Assessment
delving into a quantitative cost-benefit analysis of the direct
impacts of such a designation and a qualitative analysis of the
indirect impacts. J.A. 103–111. The Assessment also

requested public comment on thirteen discreet issues regarding
its initial cost-benefit analyses. J.A. 118.

One month later, EPA published a Notice of Proposed
Rulemaking suggesting the designation of PFOA and PFOS as
“hazardous substances” under CERCLA. See Designation of
[PFOA] and [PFOS] as CERCLA Hazardous Substances, 87
Fed. Reg. 54,415, 54,417 (Sept. 6, 2022).

In doing so, EPA requested comments specifically on:

(1) Whether CERCLA section 102(a) precludes,
allows, or requires consideration of cost in
designation decisions, and, if so, (2) which costs and
benefits of those discussed in the EA [Economic
Assessment] should be considered, (3) whether
additional benefits and costs not identified in the EA
should be considered, (4) if indirect benefits and costs
are considered, how they should be assessed in light
of the discretion and uncertainties described above,
(5) how benefits and costs could be incorporated into
the designation decision, and (6) whether designation
would be justified if costs were to be considered in the
Agency’s designation decision.

87 Fed. Reg. at 54,423.

After receiving comments, including from Petitioners,
EPA issued its final rule in May 2024. Designation, 89 Fed.
Reg. at 39,124; e.g., J.A. 681, 687, 714. EPA used two factors
to determine that PFOA and PFOS qualified as “hazardous
substances.” First, EPA considered “the potential harm to
humans or the environment from exposure to the substance
(i.e., hazard),” and second, “how the substance potentially
moves, persists, and/or changes when in the environment (i.e.,

environmental fate and transport).” Designation, 89 Fed. Reg.
at 39,141. EPA concluded that both weighed in favor of
designation, crediting the significant body of research on
adverse health effects as well as the tendency of PFOA and
PFOS to remain for many years in the environment and to
bioaccumulate in human bodies. See id. at 39,143–39,148.

EPA then assumed without deciding that CERCLA
required a cost-benefit analysis of that designation.
Designation, 89 Fed. Reg. at 39,143. EPA’s evaluation of the
costs and benefits contained both “quantitative and qualitative”
considerations. Id. at 39,149. EPA published the cost-benefit
analysis in a document entitled “Regulatory Impact
Analysis[,]” and attached it to the final rule. Id. at 39,149; J.A.
368–659.

EPA’s designation of PFOA and PFOS as “hazardous
substances” has three direct impacts on regulated parties.

First, parties responsible for a release of more than one
pound of PFOA or PFOS must report that release to national
authorities, 42 U.S.C. §§ 9602(b), 9603; Waterkeeper Alliance
v. EPA, 853 F.3d 527, 531 (D.C. Cir. 2017), and, in some cases,
to local authorities and the public, 42 U.S.C. §§ 9611(g),
11004; 40 C.F.R. § 355.

Second, federal agencies selling land contaminated with
PFOA and PFOS generally must provide notice of the presence
of hazardous substances. 42 U.S.C. § 9620(h).

Third, shippers must identify and mark shipments of
PFOA and PFOS weighing more than one pound, pursuant to
the Hazardous Materials Transportation Act of 1975, 49 U.S.C.
§ 5101 et seq., 42 U.S.C. § 9656(a); 49 C.F.R. § 171.1.

The Designation leads to indirect impacts as well. In some
circumstances, after several more regulatory steps, EPA may
compel polluters to abate and clean up releases of PFOA or
PFOS. 42 U.S.C. § 9606. In other circumstances, the federal
government, States, and adversely affected private parties may
pursue enforcement actions to recover cleanup costs from
responsible polluters. 42 U.S.C. § 9607; see 40 C.F.R.
§§ 300.410, 300.420; 42 U.S.C. § 9606(a).

Seven interest groups for various companies that use,
transport, or discharge PFOA and PFOS in their
manufacturing, transportation, and waste management
(“Petitioners”), petitioned this court to vacate the Designation.
Petitioners challenge EPA’s (1) interpretation of “hazardous
substances” to include PFOA and PFOS as contrary to law, 5
U.S.C. § 706(2)(A); (2) cost-benefit analysis as arbitrary and
capricious, id., and in violation of Administrative Procedure
Act’s notice requirement, id. § 553; and (3) decision to regulate
in the face of uncertainties as arbitrary and capricious, id.
§ 706(2)(A).
1

We have exclusive jurisdiction over these petitions for
review of a “regulation promulgated under” CERCLA. 42
U.S.C. § 9613(a).

1
Petitioners are the Chamber of Commerce of the United States
of America (“Chamber of Commerce”), American Chemistry
Council, American Fuel & Petrochemical Manufacturers, Associated
General Contractors of America, Inc., National Waste & Recycling
Association, Institute of Scrap Recycling Industries, d/b/a the
Recycled Materials Association, and American Forest & Paper
Association.

Petitioners have the jurisdictionally required Article III
associational standing. See, e.g., Students for Fair Admissions,
Inc. v. President & Fellows of Harvard College, 143 S. Ct.
2141, 2157 (2023). Petitioners have identified member
companies that use PFOA- and PFOS-containing products and
attest that they “are already seeing impacts on their overall
project expenses” in complying with the terms of CERCLA.
See Decl. of Leah Pilconis ¶¶ 19, 23–24, 27–28; Decl. of
Charles Mull ¶¶ 7, 9–12; Decl. of John M. Perkey ¶¶ 18–20;
Decl. of Anne Germain ¶ 10. Those increased expenses are
concrete injuries in fact assertedly caused by the Designation
that could be redressed by court action. In addition, the
associations’ interests in protecting companies from
CERCLA’s liability regime are germane to their missions of
promoting the financial and regulatory interests of private
industry. See Decl. of Martin Durbin ¶ 5; Decl. of Anne
Germain ¶ 3; Decl. of Leah Pilconis ¶¶ 4–5. Petitioners also
have shown that the participation of individual members is not
required to seek the equitable relief of vacatur. See Center for
Biological Diversity v. EPA, 56 F.4th 55, 67 (D.C. Cir. 2022).

In reviewing Petitioners’ contrary to law claims, we must
independently determine the “best” reading of CERCLA’s text
by “applying all relevant interpretive tools.” Loper Bright
Enters. v. Raimondo, 144 S. Ct. 2244, 2266 (2024). Our review
of Petitioners’ arbitrary and capricious claims is “deferential”
to the agency. FCC v. Prometheus Radio Project, 141 S. Ct.
1150, 1158 (2021) (“A court simply ensures that the agency
has acted within a zone of reasonableness and, in particular, has
reasonably considered the relevant issues and reasonably
explained the decision.”); see also Meritor, Inc. v. EPA, 966
F.3d 864, 869 (D.C. Cir. 2020) (“In conducting this review, we

afford the EPA significant deference with respect to the highly
technical issues involved.”) (formatting modified).

Finally, we must set aside a rule if the agency failed to
provide the requisite notice and comment and the petitioner has
shown prejudice. 5 U.S.C. § 553(b); Petaluma FX Partners,
LLC v. Commissioner, 792 F.3d 72, 81 (D.C. Cir. 2015).

III

Petitioners advance three challenges to the Designation.
They contend that: (1) EPA misinterpreted the term “may
present substantial danger” in CERCLA’s definition of a
hazardous substance; (2) EPA’s cost-benefit analysis provided
insufficient notice to the parties; and (3) EPA’s cost-benefit
analysis and decision to regulate in the face of uncertainty were
arbitrary and capricious.

None of those claims succeeds. The plain language of
Section 9602 allows EPA to designate as hazardous substances
chemicals like PFOA and PFOS that repeatedly have been
linked to adverse health effects in myriad peer-reviewed
studies. EPA provided adequate notice of its cost-benefit
analysis underlying the ultimate Designation through its earlier
Economic Assessment and request for comments on it. Finally,
EPA acted reasonably based on the record before it in its
calculation of costs and benefits, and in its decision to take this
regulatory step of designating PFOA and PFOS to be
hazardous substances.

Petitioners argue that, in interpreting the phrase “may
present substantial danger” in CERCLA’s definition of a
hazardous substance, EPA had to find that substantial danger

“will” occur upon release to avoid overinclusion and to comply
with the nondelegation and void-for-vagueness doctrines.
Pet’rs’ Reply Br. 14; Pet’rs’ Opening Br. at 31–32. Petitioners
are wrong as a matter of statutory text and precedent.

The plain statutory text refutes Petitioners’ argument.
CERCLA provides that EPA “shall” “designat[e] as hazardous
substances” those “elements, compounds, mixtures, solutions,
and substances which, when released into the environment may
present substantial danger to the public health or welfare or the
environment[.]” 42 U.S.C. § 9602(a).

In making the Designation, EPA determined that “may”
means “at a minimum, there is a possibility” that the released
substance presents a substantial danger to public health,
welfare or the environment, and that “EPA need not have
certainty” of that danger. Designation, 89 Fed. Reg. at 39,141.

Petitioners challenge EPA’s interpretation of “may[,]”
arguing that reading it to mean a “possibility” of substantial
harm lacks “fix[ed] boundaries” and is “unreasonably broad.”
Pet’rs’ Opening Br. 28–29 (secondly quoting Loper Bright, 144
S. Ct. at 2263). According to Petitioners, “may” in the statute
means that whenever a substance is released, the danger “will
be actually existing or real.” Pet’rs’ Reply Br. 12–13
(quotation marks omitted).

EPA has the best reading of the statute as a matter of text
and context.

To start, the statute straightforwardly uses “may” to refer
to the chance of harm to public health, not its certainty. The
primary meaning of “may” is one of contingency both in

ordinary usage and in dictionaries at the time of CERCLA’s
enactment. See May, BLACK’S LAW DICTIONARY (5th ed.
1979) (“An auxiliary verb qualifying the meaning of another
verb by expressing ability, competency, liberty, permission,
possibility, probability or contingency.”); May, B
ALLENTINE’S
LAW DICTIONARY 785 (3d. ed. 1969) (“Ordinarily a
permissive, rather than a mandatory, term in a statute.”); May,
O
XFORD AMERICAN DICTIONARY 410 (1980) (“expressing
possibility (it may be true)”); May, W
EBSTER’S THIRD NEW
INTERNATIONAL DICTIONARY 1396 (1981) (“be in some degree
likely to” as in “you [may] be right”); May, WEBSTER’S NEW
WORLD DICTIONARY 463 (2d Concise ed. 1982) (“possibility
or likelihood [it may rain]”); May, THE RANDOM HOUSE
DICTIONARY OF THE ENGLISH LANGUAGE 1189 (2d unabr. ed.
1987) (“used to express possibility” as in “[i]t may rain”).

Even more to the point, the statute says when that
contingency should be assessed, which is at the time—
“when”—the substance is “released into the environment[.]”
42 U.S.C. § 9602(a). In that way, the statute directs EPA to
forecast the future risk of harm at the time of a release.

Petitioners’ insistence that the harm must be certain to
occur at the time of release rewrites rather than interprets the
statutory text. If Congress wanted to adopt Petitioners’
preferred approach, it would have said: “substances which,
when released into the environment may will present
substantial danger to the public health or welfare or
the environment[.]” Compare Pet’rs’ Reply Br. 12–13 (“[I]f
the condition of release is satisfied, the result of substantial
danger to the public health or welfare or the environment will
be actually existing or real.”) (quotation marks omitted), with
42 U.S.C. § 9602(a) (using simply “may”).

Also, the dictionaries on which Petitioners rely refute their
argument, providing that the word “may” will not be treated as
a word of command or requirement “unless there is something
in [the] context” of a statute “to indicate that it was used in such
sense.” May, B
LACK’S LAW DICTIONARY (5th ed. 1979); see
also May, BALLENTINE’S LAW DICTIONARY 785 (3d. ed. 1969)
(“Discretionary in its grammatical sense, but subject to
construction as mandatory where the sense of the entire context
impels such construction[.]”) (emphasis added). Missing from
Petitioners’ argument is anything in the context that impels
overriding the ordinary meaning of “may[.]”

Petitioners also forget that, in CERCLA, Congress wrote a
statute that would operate on the basis of scientific knowledge
and information about health and environmental risks.
Congress presumably knew that “[s]cientists typically speak
not of certainty, but of probability; they are trained to act on
probabilities that statistically constitute ‘certainties.’” Ethyl
Corp. v. EPA, 541 F.2d 1, 25 n.52 (D.C. Cir. 1976) (en banc);
see also id. (“Even scientific ‘facts’ are not certain, but only
theories with high probabilities of validity.”); cf. Center for
Biological Diversity v. EPA, 749 F.3d 1079, 1090 (D.C. Cir.
2014) (“[A statute] may at times require * * * action in the face
of uncertainty, lest ‘the precautionary purpose of the statute’ be
undermined.”) (quoting Ethyl Corp., 541 F.2d at 28). To
require absolute scientific certainty as to what will happen
upon every individual release of a dangerous chemical would
have been to legislatively paralyze CERCLA.

Petitioners worry that such an ordinary and contextual
reading of the text would permit EPA to categorize table salt as
a hazardous substance. Petitioners’ argument overlooks the
required finding that a release may present “substantial danger”
to public health, welfare, or the environment. 42 U.S.C.
§ 9602(a). That criterion has real bite. The risk of harm must

be both serious and real, not hypothesized. See Substantial,
BLACK’S LAW DICTIONARY (5th ed. 1979) (“actually existing;
real; not seeming or imaginary; not illusive; solid; true;
veritable”); Substantial, O
XFORD AMERICAN DICTIONARY 683
(1980) (“of considerable amount or intensity or validity”);
Substantial, W
EBSTER’S THIRD NEW INTERNATIONAL
DICTIONARY 2280 (1981) (“considerable in amount, value, or
worth”); Substantial, XVII T
HE OXFORD ENGLISH DICTIONARY
66 (2d ed. 1989) (“That is, or exists as, a substance; having a
real existence”); Danger, B
LACK’S LAW DICTIONARY (5th ed.
1979) (“Jeopardy; exposure to loss or injury; peril.”); Danger,
OXFORD AMERICAN DICTIONARY 160 (1980) (“liability or
exposure to harm or to death”); Danger, WEBSTER’S THIRD
NEW INTERNATIONAL DICTIONARY 573 (1981) (“Harm, Injury,
Damage”) (capitalization altered); Danger, IV THE OXFORD
ENGLISH DICTIONARY 241 (2d ed. 1989) (“Liability or
exposure to harm or injury; the condition of being exposed to
the chance of evil; risk, peril.”).

More to the point, this case does not require rigidly
defining the precise boundaries of the term “substantial
danger[.]” That is because, for all their verbal debating,
Petitioners tellingly do not dispute that PFOA and PFOS
qualify as substances that may pose a substantial risk to public
health, welfare, and the environment if released. Nor could
they. The Designation cited dozens of studies showing
“[c]ollectively” that “each PFOA and PFOS individually
pose[s] a human health hazard[.]” Designation, 89 Fed. Reg.
at 39,144. The Designation spent three full pages cataloguing
just “some” of the health conditions associated with PFOA and
PFOS exposure: developmental effects including decreased
infant birth weight and effects on fetuses during pregnancy;
cardiovascular impacts like increased cholesterol in
adolescents; increased liver enzymes, which can impact liver
function; immunosuppression in adults and children; impacted

thyroid function; and preeclampsia and gestational
hypertension in pregnant women. Id. at 39,144–39,146.

That is not all. After reviewing toxicity assessments in
drinking water, EPA classified PFOA and PFOS as “likely to
be carcinogenic to humans[.]” Designation, 89 Fed. Reg. at
39,143 (formatting modified). The PFOA determination was
based on “evidence of kidney and testicular cancer in humans
and Leydig cell tumors, pancreatic acinar cell tumors, and
hepatocellular adenomas in rats.” Id. at 39,144. So too was the
PFOS determination based on “evidence of hepatocellular
tumors in humans and rats, pancreatic islet cell carcinomas in
male rats, and mixed but plausible evidence of bladder,
prostate, kidney, and breast cancers in humans[.]” Id.

EPA is not alone in these concerns. As the Designation
noted, the International Agency for Research on Cancer, a
subsidiary of the World Health Organization, has categorized
PFOA as “carcinogenic to humans” and PFOS as “possibly
carcinogenic to humans[.]” Designation, 89 Fed. Reg. at
39,143.

Lastly, Petitioners’ worry overlooks the political
accountability issues that would arise from a misguided
designation. In addition, Petitioners could voice objections to
an unreasonable designation in the ordinary course of notice
and comment rulemaking and, if necessary, bring suit to
challenge the final designation as contrary to law.

For all of these reasons, the phrase “may present a
substantial risk of harm” when released into the environment

carries its plain meaning of a scientifically possible substantial
risk of harm upon release.
2

Petitioners next argue that the definition of “hazardous
substances” must be read more narrowly than “pollutant or
contaminant” because “CERCLA confers significantly more
authority to address ‘hazardous substances’ than ‘pollutants or
contaminants.’” Pet’rs’ Opening Br. 33. Petitioners are
mistaken.

To start, Petitioners’ insistence that courts must enforce
some inflexible hierarchy between these two categories is not
supported by anything in the statutory text. Their definitions
each require a probability of substantial danger to the public or
environmental organisms. Compare 42 U.S.C. § 9601(33)
(defining a “pollutant or contaminant” as a substance which
“will or may reasonably be anticipated to cause death, disease,
behavioral abnormalities, cancer, genetic mutation,
physiological malfunctions (including malfunctions in
reproduction) or physical deformations” in animals and
humans), and id. § 9604(a) (requiring EPA to determine that
pollutants or contaminants “may present an imminent and

2
Petitioners urge us not to afford EPA’s interpretation any
“respect” in our interpretation of Section 9602 because of (1) a 1983
notice of proposed rulemaking, which never materialized into a final
rule, proposing quantitative metrics to operationalize Section 9602,
and (2) regulations with more concrete metrics that implement
Section 9605, a part of CERCLA that does not use the word “may.”
Pet’rs’ Opening Br. 35 & n.12 (citing Loper Bright Enters., 144 S.
Ct. at 2258). Contrary to Petitioners’ contention, non-rules and
definitions in materially different regulations do not show
inconsistency with prior agency positions. More to the point, our
decision is made de novo without deference to EPA’s view.

substantial danger to the public health or welfare” before
initiating cleanup), with id. § 9602(a) (defining “hazardous
substances” as those which “may present substantial danger to
the public health or welfare or the environment”).

So CERCLA does not draw a comparative-harm line
between pollutants or contaminants and hazardous substances.
Instead, it creates two distinctive cleanup regimes with two
different paths for designation. The difference in how
hazardous substances and pollutants or contaminants are
treated in cleanups turns on (1) the imminence of harm and (2)
whether the risk of harm posed is uniform or could vary based
on site-specific conditions.

Pollutants or contaminants are identified for clean up on a
site-by-site basis based both on the risk of harm and—
uniquely—the harm’s “imminen[ce.]” 42 U.S.C. § 9604(a)(1);
Designation, 89 Fed. Reg. at 39,172. In addition, CERCLA
does not require EPA to promulgate any regulations or make
formal certifications to designate substances as pollutants or
contaminants, presumably because the imminence of harm may
not allow for such delays. See 42 U.S.C. § 9604(a)(1).

On the other hand, CERCLA mandates that EPA designate
hazardous substances in a single rulemaking that then applies
to all CERCLA sites. 42 U.S.C. § 9602. While Section 9602
does not explicitly call for notice and comment rulemaking,
EPA opted to do so for the PFOA and PFOS Designation, and
committed itself to further notice-and-comment rulemaking if
it were to update the Designation. Designation, 89 Fed. Reg.
at 39,174.

To the extent the statutory scheme allows substances, like
PFOA and PFOS, to originally qualify as pollutants or
contaminants and then later, be designated hazardous

substances based on advances in scientific knowledge, that is
the “belt and suspenders approach” that CERCLA’s text and
context straightforwardly allow. Atlantic Richfield Co., 140 S.
Ct. at 1350 n.5.

Finally, Petitioners contend that EPA’s reading of Section
9602 runs afoul of the nondelegation and void-for-vagueness
doctrines, and that we should reject EPA’s reading to avoid
those constitutional questions. Pet’rs’ Opening Br. 31–32.
There are no such constitutional concerns in this case.

Allowing agencies to make discretionary judgments
informed by evidence fully comports with the nondelegation
doctrine as long as “Congress has set out an ‘intelligible
principle’ to guide what it has given the agency to do.” FCC
v. Consumers’ Rsch., 145 S. Ct. 2482, 2497 (2025) (quoting
J.W. Hampton, Jr., & Co. v. United States, 276 U.S. 394, 409
(1928)). Under the “intelligible principle” test, courts require
Congress to “ma[ke] clear both the general policy that the
agency must pursue and the boundaries of its delegated
authority.” Id. (formatting modified).

Congress has laid out the “general policy” for EPA to
pursue—regulating substances that are particularly harmful to
humans and the environment by creating a cleanup and cost-
allocation scheme that puts the onus on polluters rather than
taxpayers. See 42 U.S.C. §§ 9602, 9606, 9607; cf. United
States v. E.I. Dupont De Nemours & Co., 432 F.3d 161, 169
(3d Cir. 2005) (“Congress’s decision to hold responsible
parties strictly liable for the government’s costs of responding
to hazardous waste contamination [in CERCLA] is both a
reasonable exercise of legislative authority and different in

kind from the unbounded delegation” found in cases that run
afoul of the nondelegation doctrine.).

Congress also has set fixed “boundaries” for the agency’s
authority and “provided sufficient standards” for courts to
police agency compliance. Consumers’ Rsch., 145 S. Ct. at
2497. For example, to categorize substances as “hazardous,”
EPA must determine that they are harmful enough to risk
“substantial danger” to human welfare or the environment. 42
U.S.C. § 9602(a).

Tying EPA’s decisions to scientific findings based on a
public health standard easily satisfies the requirement that there
be an intelligible principle to limit agency action. See, e.g.,
Consumers’ Rsch., 145 S. Ct. at 2501–2503 (finding an
intelligible principle in the Telecommunications Act’s
requirement that subsidies paid by telecommunications carriers
be enough to “contribute” to “sufficient mechanisms * * * to
preserve and advance universal service[,]” 47 U.S.C. § 254(d));
Whitman v. American Trucking Ass’ns, 531 U.S. 457, 465
(2001) (same for Clean Air Act’s delegation to EPA to set
ambient air quality standards “‘the attainment and maintenance
of which * * * are requisite to protect the public health’ with
‘an adequate margin of safety’”) (quoting 42 U.S.C.
§ 7409(b)(1)); Touby v. United States, 500 U.S. 160, 163, 165
(1991) (same for Controlled Substances Act’s authorization of
the Attorney General to temporarily add a substance to a
controlled drug schedule if doing so is “necessary to avoid an
imminent hazard to the public safety”) (quoting 21 U.S.C.
§ 811(h)(1)); see also Sessions v. Dimaya, 584 U.S. 148, 159
(2018) (“Many perfectly constitutional statutes use imprecise
terms like ‘serious potential risk’ * * * or ‘substantial risk[.]’”).

Section 9602’s plain meaning also fully comports with the
Fifth Amendment’s Due Process Clause by affording “the

person of ordinary intelligence a reasonable opportunity” to
predict whether a substance could be designated hazardous.
Grayned v. City of Rockford, 408 U.S. 104, 108–109 (1972).
Notice is particularly easy to find here given that PFOA and
PFOS previously have been designated under CERCLA as
“pollutant[s] or contaminant[s]” that “will or may reasonably
be anticipated to cause death, disease, behavioral
abnormalities, cancer, genetic mutation, physiological
malfunctions (including malfunctions in reproduction) or
physical deformations[.]” 42 U.S.C. § 9601(33); Designation,
89 Fed. Reg. at 39,173. That alone provided fair notice that
PFOA and PFOS might also qualify as “hazardous
substances[.]”

Beyond that, Petitioners’ members are seasoned
participants in the highly regulated area of chemical
substances’ commercial uses. They were provided ample
notice and opportunity to be heard through the notice and
comment rulemaking process that designated PFOA and PFOS
as hazardous substances, followed by judicial review. See
Village of Hoffman Ests. v. The Flipside, Hoffman Ests., Inc.,
455 U.S. 489, 498 (1982) (“[E]conomic regulation is subject to
a less strict vagueness test because * * * the regulated
enterprise may have the ability to clarify the meaning of the
regulation by its own inquiry, or by resort to an administrative
process.”).

For all those reasons, affording Section 9602’s “may
present substantial danger to the public health or welfare or the
environment” language its ordinary meaning comports fully
with the nondelegation doctrine and due process. Petitioners’
contrary to law claim fails.

The second chapter in Petitioners’ challenge focuses on
EPA’s cost-benefit analysis. Petitioners argue that EPA
(1) violated the APA’s notice requirement by failing to disclose
its Regulatory Impact Analysis until publication of the final
rule, and (2) conducted its cost-benefit analysis in an arbitrary
and capricious manner. Pet’rs’ Opening Br. 41–49.

Petitioners’ arguments do not hold up. The Regulatory
Impact Analysis was a logical outgrowth of the Economic
Assessment’s cost-benefit analysis, which was then
supplemented with data to address comments made by
Petitioners and others. EPA also reasonably explained its
quantitative analyses.
3

First, Petitioners contend that EPA failed to provide
adequate notice of its cost-benefit analysis. While they
acknowledge that the Economic Assessment provided with the
notice of proposed rulemaking contained a cost-benefit
analysis, Petitioners argue that the final Regulatory Impact
Analysis differed such that they were no longer provided
sufficient notice. Pet’rs’ Opening Br. 43.

The APA requires that a notice of proposed rulemaking
include “either the terms or substance of the proposed rule or a
description of the subjects and issues involved,” 5 U.S.C.
§ 553(b)(3), and “give interested persons an opportunity to

3
Because we reject Petitioners’ challenges to EPA’s cost-
benefit analysis, we need not decide whether EPA was required to
consider such costs in the first instance. EPA assumed without
deciding that it had to do so, 89 Fed. Reg. at 39,143, and we do the
same.

participate in the rule making through submission of written
data, views, or arguments,” id. § 553(c). Notice “ensure[s] that
agency regulations are tested via exposure to diverse public
comment,” promotes fairness to impacted parties, and gives
them “an opportunity to develop evidence in the record to
support their objections[.]” International Union, United Mine
Workers v. Mine Safety & Health Admin., 626 F.3d 84, 95
(D.C. Cir. 2010) (formatting modified). This notice
requirement extends to “critical information” on which the rule
is based. GPA Midstream Ass’n v. Department of
Transportation, 67 F.4th 1188, 1197 (D.C. Cir. 2023).

Our test for whether an agency has met the APA’s notice
requirement is whether “affected parties should have
anticipated the final rule in light of the notice.” Brennan v.
Dickson, 45 F.4th 48, 69 (D.C. Cir. 2022) (quotation marks
omitted). The key question is whether the final rule is a
“logical outgrowth” of the proposal. National Ass’n of
Broadcasters v. FCC, 147 F.4th 978, 992 (D.C. Cir. 2025)
(quotation marks omitted).

The Regulatory Impact Analysis was a logical outgrowth
of the Economic Assessment and notice and comment process.
First, its cost-benefit analysis reasonably followed from the
notice of proposed rulemaking and related Economic
Assessment. Second, the additional cost data was not
information “critical” to the final decision.

Petitioners first contend that they lacked notice that EPA
would pursue a cost-benefit analysis in the final rule. Because
they had been put on notice by the Economic Assessment, and

the Regulatory Impact Analysis was the logical outgrowth of
that initial cost-benefit analysis, Petitioners’ argument fails.

The content of a final rule is the logical outgrowth of an
agency’s earlier proposal if “a party c[ould] reasonably
anticipate” the outcome “in light of the initial notice as a
guidepost.” National Ass’n of Broadcasters, 147 F.4th at 992
(quotation marks omitted).

Petitioners do not and cannot dispute that they were on
notice that EPA was considering a full cost-benefit analysis
that would build on the initial cost-benefit analysis already
provided in the Economic Assessment, which was incorporated
into the notice of proposed rulemaking. 87 Fed. Reg. at 54,418
n.4. The notice, after all, included the following “Request for
Comment”:

EPA is taking comment on its approach to the
consideration of costs, including: (1) Whether
CERCLA section 102(a) precludes, allows, or
requires consideration of cost in designation
decisions, and, if so, (2) which costs and benefits of
those discussed in the EA [Economic Assessment]
should be considered, (3) whether additional benefits
and costs not identified in the EA should be
considered, [and] (4) if indirect benefits and costs are
considered, how they should be assessed in light of
the discretion and uncertainties described above[.]

Id. at 54,423.

Petitioners next contend that even if they did have notice
that EPA would conduct a cost-benefit analysis, the Economic
Assessment “bore no resemblance” to the Regulatory Impact
Analysis because the latter included estimates of indirect costs

that EPA had previously assessed qualitatively. Pet’rs’
Opening Br. 43. That argument misunderstands the logical
outgrowth standard.

Because “the very premise of agencies’ duty to solicit,
consider, and respond appropriately to comments is that rules
evolve from conception to completion[,]” this court does not
require that a final rule avoid any material change from the
notice of proposed rulemaking. Brennan, 45 F.4th at 69; see
id. (“[T]he APA does not require that rules be subjected to
multiple cycles of notice and comment until the version
adopted as final is identical to the last notice of proposed
rulemaking[.]”); Connecticut Light & Power Co. v. Nuclear
Regul. Comm’n, 673 F.2d 525, 533 (D.C. Cir. 1982) (“The
agency need not renotice changes that follow logically from or
that reasonably develop the rules it proposed originally.
Otherwise, the comment period would be a perpetual exercise
rather than a genuine interchange resulting in improved
rules.”).

As with any final rule that has adapted in response to
critical public comments, then, there were changes between the
Economic Assessment and the Regulatory Impact Analysis.
As Petitioners point out, the Economic Assessment performed
a qualitative assessment that included more high-level cost-
benefit considerations such as whether “harness[ing] the
efficiency and expertise of the private sector” in shifting the
costs of cleanup to polluters rather than the government would
result in lower costs than the current baseline, given that PFOA
and PFOS had been designated as pollutants or contaminants
at select Superfund sites. J.A. 144.

That does not mean that Petitioners lacked notice that EPA
might perform a quantitative analysis in the final rule. Notably,
the Economic Assessment’s qualitative analysis included

quantitative cost estimates as well. EPA cited a 2019 study on
the “historical average” cost of remedial actions at sites on the
National Priorities List, estimating that range to be “between
$35.2 and $48.2 million per site.” J.A. 149. And further,
recognizing the “lack of information and systemic analysis of
remediation of PFOS and PFOA” specifically, EPA explicitly
sought “information and comment that may allow EPA to
estimate incremental indirect costs associated with this rule.”
J.A. 148.

That EPA made changes between the quantitative
estimates in the Economic Assessment and the Regulatory
Impact Analysis is proof that notice and comment rulemaking
is working as it should. The whole point of this kind of
rulemaking is for the agency to learn, adapt, and change its
proposed action in response to public input if warranted.
Brennan, 45 F.4th at 69.

Further, so long as an agency has “expressly asked for
comments on a particular issue or otherwise made clear that the
agency was contemplating a particular change[,]” the APA
notice requirement has been met. Brennan, 45 F.4th at 69.
That is the case here. Petitioner the Chamber of Commerce
and others submitted comments calling on EPA to conduct a
Regulatory Impact Analysis. J.A. 212, 326, 339. The Chamber
of Commerce also submitted a detailed cost-benefit analysis,
including its own models for a quantitative cost calculation of
impacts on private parties, to be included in that Regulatory
Impact Analysis. See J.A. 212–220.

Other commentators similarly propounded direct and
indirect costs not identified in the Economic Assessment for
EPA to address in formulating a final rule. See, e.g., J.A. 242–
243 (identifying categories of costs “left unaddressed in the
economic assessment” relating to possible “over-adjustment”

in PFAS treatment by companies seeking to avoid CERCLA
liability); J.A. 285 (estimating increased annual costs of “PFAS
management” for municipal solid waste landfills); J.A. 340
(estimating increased costs to the solid waste sector); J.A. 364–
365 (urging EPA to increase its upper-bound estimate of direct
costs).

EPA heeded those demands and included additional cost
estimations and a more detailed cost-benefit analysis in the
Regulatory Impact Analysis. See J.A. 525–595. In response to
the Chamber of Commerce’s Coalition of Companies and
Trade Associations’ comments that the Economic
Assessment’s $370,000 estimate for an upper-bound cost of
annual notifications was “simply not representative” of the true
cost, J.A. 365, EPA increased its upper-bound estimation of
those costs to $1,630,000, J.A. 528–529. In response to that
same party’s comments that EPA’s qualitative approach to
indirect costs was insufficient, see J.A. 363, 365, the agency
added a quantitative analysis to its consideration of indirect
costs, J.A. 534–571.

In this way, the Designation’s cost-benefit analysis
evolved logically from the notice of proposed rulemaking and
Economic Assessment in light of comments submitted by
Petitioners and others such that Petitioners “should have
anticipated the final rule in light of the notice[.]” Brennan, 45
F.4th at 69 (quotation marks omitted). In addition, as long as
the agency provides “notice” in its proposed rulemaking that it
may elect to proceed with a qualitative rather than quantitative
analysis, the agency’s “way of proceeding” qualifies as a
“‘logical outgrowth’ of the notice[.]” Mozilla Corp. v. FCC,
940 F.3d 1, 70 (D.C. Cir. 2019) (per curiam). The same is true
for the reverse situation here, where EPA sought comment on
whether it should proceed with a quantitative analysis in the

final rule, 87 Fed. Reg. at 54,423, and Petitioners proposed that
it do just that, see J.A. 212–220.

Because the cost-benefit analysis in the Designation and
its accompanying Regulatory Impact Analysis logically
followed from the notice of proposed rulemaking and
incorporated Economic Assessment, the changes made to the
final rule and its cost-benefit analysis satisfy the APA’s notice
requirement.

Petitioners next contend that EPA withheld critical
information in the form of the “specific methodology, data, and
assumptions that EPA used to evaluate cost in the Final Rule.”
Pet’rs’ Opening Br. 46–47.

Petitioners are correct that an agency must share “critical
information” upon which a final rule is based and subject it to
public comment. GPA Midstream Ass’n, 67 F.4th at 1197;
Owner-Operator Indep. Drivers Ass’n v. Federal Motor
Carrier Safety Admin., 494 F.3d 188, 199 (D.C. Cir. 2007). At
the same time, we do not require repeated rounds of notice and
comment “when additional fact gathering merely supplements
information in the rulemaking record[.]” Chamber of
Commerce of the U.S. v. SEC, 443 F.3d 890, 900 (D.C. Cir.
2006). Supplementary information “expands on and confirms
information” in the notice of proposed rulemaking, “and
addresses alleged deficiencies in the pre-existing data[.]” Id.
(quotation marks omitted).

Supplementation of the cost-benefit analysis is exactly
what happened here. Though EPA added some additional data
and basic calculations of indirect cost predictions, those
additions merely supplemented what had been put forward in

the Economic Assessment, which was incorporated as part of
the notice of proposed rulemaking.

True, EPA added some additional data and basic
calculations of cost probability distributions to its calculations
of indirect costs, but that just built on the data and qualitative
analyses that EPA had put out for notice and comment. The
additional data of which Petitioners complain was added in
response to comments and simply “expand[ed] on and
confirm[ed]” the data and analysis provided in the Economic
Assessment. Chamber of Commerce, 443 F.3d at 900 (quoting
Solite Corp. v. EPA, 952 F.2d 473, 484 (D.C. Cir. 1991) (per
curiam)).

Take the estimated cleanup costs for sites listed on the
National Priorities List, on which Petitioners say they had no
opportunity to comment. Pet’rs’ Opening Br. 46. The
Economic Assessment provided estimates of these costs “for
reference[,]” pointing to a 2019 study that calculated the
historic average cost of cleanups at these sites to be between
$35.2 and $48.2 million per site. J.A. 148–149. That number
was not perfect, EPA noted, because those were cleanups of all
hazardous substances at a site, and it is possible that cleanup of
PFOA and PFOS would not add significantly to the existing
cleanup costs of other preexisting hazardous substances at
these sites. J.A. 149. The Regulatory Impact Analysis then
calculated the estimated increase in cleanup costs after the
designation of PFOA and PFOS as hazardous substances to be
between $10.3 million and $51.7 million. J.A. 567. That lower
end is significantly lower than that in the 2019 study, but that
follows from EPA’s explanation in the Economic Assessment
that, where cleanup efforts are already ongoing, the marginal
increase in cost to add two additional hazardous substances
would often not significantly add to the cleanup costs. See J.A.
149. And the Regulatory Impact Analysis’s upper-bound

estimation of $51.7 million is just a hair’s breadth away from
the 2019 study’s upper-bound of $48.2 million, after
accounting for inflation over the intervening five years.

Nor could it have been a surprise to Petitioners that the
cleanup costs at sites not on the National Priorities List were
estimated to be significantly lower than the cleanup costs at
sites on the List. Compare J.A. 546, with J.A. 567. As EPA
explained in the notice of proposed rulemaking, the sites on the
National Priorities List are considered “among the worst
hazardous substance sites” in the country, 87 Fed. Reg. at
54,420, which almost always renders cleanups at those sites
larger undertakings with higher price tags.

Petitioners also take issue with the Regulatory Impact
Analysis’s “calculation of quantified benefits” at sites on the
National Priorities List, complaining that they “had no chance
to address” this calculation. Pet’rs’ Opening Br. 46. But
because of difficulties in estimating the exact monetary value
of benefits to human health and the environment, EPA did not
tally up a total “benefit” amount, relying instead on
“illustrative” examples of some benefits, including cleaner well
water and higher property values near impacted sites. See J.A.
579–584. These new data points are just case studies and
illustrations of the benefits previewed in the Economic
Assessment. See J.A. 144–147. The data, drawn in part from
studies put forward by commenters, see J.A. 242 & n.7; J.A.
584 & n.301, serve simply to “confirm” the qualitative
assessment of these benefits previously put forward. J.A. 694,
696 (emphasis omitted). A new round of notice and comment
for confirmatory material is not required. See Owner-
Operator, 494 F.3d at 201 (“[A]n agency does not violate the
APA if its methodology remains constant and new data is
merely used to check or confirm prior assessments.”)
(formatting modified). That is especially appropriate here,

where Petitioners are challenging a cost-benefit analysis that
responded to their own comments that EPA should have used
a more quantitative approach. See J.A. 212–213, 361, 363.
They cannot be prejudiced by getting what they asked for.

Petitioners rely on Owner-Operator Independent Drivers
Association v. Federal Motor Carrier Safety Administration,
494 F.3d 188 (D.C. Cir. 2007), to argue that even when an
agency makes only one change to its cost-benefit analysis, it
must go through another round of notice and comment, id. at
200–201; Pet’rs’ Opening Br. 44, 46.

Owner-Operator imposed no such categorical rule. In that
case, the Federal Motor Carrier Safety Administration
promulgated a final rule regulating the hours a commercial
vehicle driver could work without resting. 494 F.3d at 195–
196. That rule relied on a novel cubic curve that was first
presented in the Regulatory Impact Analysis. Id. at 200. This
“entirely new” methodology of graphing, which “derived
[from] a regression equation,” was “a central component of the
justification” for the final rule. Id. at 199–201. Notably, the
new cubic curve was how the agency had justified increasing
the daily driving hours from ten hours to eleven hours. See id.
at 200–202. While prior studies in the record based on a
national database of crash statistics supported a ten-hour
driving limit, the new cubic curve “substantially” shrunk the
estimated crashes related to fatigue between hours ten to
eleven. Id. at 200. Because of the new methodology’s
centrality to the change in regulation, we held that it was “not
a minor modification used to check or confirm prior analyses”
or to supplement data, but instead was “central” to the agency’s
decision. Id. at 201.

Nothing so novel or unforeseeable happened in the
Designation’s Regulatory Impact Analysis. EPA employed no

novel methodology to reach a materially new or different
conclusion. Instead, the final rule simply used corroborating
data to confirm quantitatively its prior qualitative analysis after
receiving comments from Petitioners and others urging it to
perform just such a quantitative analysis. See Owner-
Operator, 494 F.3d at 201 (“[A]n agency does not violate the
APA if its methodology remains constant and new data is
merely used to check or confirm prior assessments.”)
(formatting modified).

Petitioners separately argue that EPA’s cost-benefit
analysis was arbitrary and capricious because, in their view,
EPA (1) miscalculated cleanup costs at sites on the National
Priorities List, (2) miscalculated costs at sites off of the
National Priorities List, (3) ignored cleanup costs at federal
sites, (4) disregarded the impact on certain industries, (5)
incorrectly assessed benefits, and (6) failed to consider the
impact of the Designation on small businesses. See Pet’rs’
Opening Br. 50–65. Petitioners are mistaken on all six fronts.

Petitioners voice a number of complaints with EPA’s
estimation of cleanup costs at National Priorities List sites.

To start, they object to EPA assuming that it was already
expending costs to clean up PFOA and PFOS at these sites as
pollutants or contaminants. Pet’rs’ Opening Br. 50. According
to Petitioners, EPA failed to show that it was cleaning up PFOA
and PFOS at these sites or that it even had the statutory power
to clean up these substances as pollutants or contaminants.

Petitioners have their facts wrong. EPA noted in the final
rule: “EPA has already identified and treated PFOA and PFOS
as pollutants and contaminants at multiple Superfund sites,
including the Saint-Gobain Performance Plastics facility in
Hoosick Falls, New York, and the Blades Groundwater site in
Blades, Delaware.” Designation, 89 Fed. Reg. at 39,173. So
it was reasonable for EPA, given its on-point experience, to
consider only the marginal costs beyond what was already
incurred for cleanup of PFOA and PFOS as pollutants or
contaminants.

Next, Petitioners assert that the Designation “warps EPA’s
incentives” because it “encourages EPA to clean up sites it
might deem too expensive to clean up itself by allowing EPA
to recover those costs from others.” Pet’rs’ Opening Br. 51.

The Designation does not create an incentive problem—it
solves one. The Designation shifts the burden to the very
private parties that deposit hazardous substances at the site,
rather than allowing those parties to spread these two forever
chemicals and expect taxpayers to clean up after them. That is
the core purpose of CERCLA: “to promote the timely cleanup
of hazardous waste sites and to ensure that the costs of such
cleanup efforts [are] borne by those responsible for the
contamination.” Atlantic Richfield Co., 140 S. Ct. at 1345
(quoting CTS Corp., 573 U.S. at 4) (alteration in original).

Petitioners also challenge the reasonableness of EPA’s
estimation of increased cleanup costs at sites that contain other
hazardous substances in addition to PFOA and PFOS. Pet’rs’
Opening Br. 52–53. In estimating those costs, EPA “ma[de]
the conservative assumption that there [would be] a cost
premium”—that is, a marginal increase in costs for PFOA and
PFOS cleanups beyond the ongoing efforts. J.A. 553–554.
Rather than assuming a single premium, EPA analyzed a range

of scenarios, with the cost premium varying from 2% to 10%.
J.A. 553–554, 563–565. Petitioner Chamber of Commerce also
baked a cost premium into its estimates, but assumed, based in
part on “its own research,” that the premium could range from
5% to 100%. J.A. 215–216. EPA rejected the high end of those
estimates, see J.A. 563–565.

This court “do[es] not review EPA’s cost figuring de novo,
but accord[s] EPA discretion to arrive at a cost figure within a
broad zone of reasonable estimat[ion.]” National Wildlife
Fed’n v. EPA, 286 F.3d 554, 563 (D.C. Cir. 2002) (per curiam)
(quoting Weyerhaeuser Co. v. Costle, 590 F.2d 1011, 1049
(D.C. Cir. 1978)). Given “the complex nature of economic
analysis typical in the regulation promulgation process,
[Petitioners’] burden to show error is high.” Id.

Petitioners have not met that burden. EPA reasonably
explained why it modeled marginal costs as it did. The agency
pointed out that, “in many cases[,]” the necessary infrastructure
to treat PFOA and PFOS would already be in place at
hazardous-waste sites because it is also required to remove and
redress other hazardous substances. J.A. 554. In addition,
“some of the same treatment technologies for PFOA and PFOS
contamination” would “likely be[] applied for other hazardous
substances in many cases.” J.A. 554. Because of EPA’s
factfinding that “infrastructure may already be in place” to
address PFOA and PFOS at most sites already on the National
Priorities List, EPA reasonably concluded that the marginal
cost increase of addressing PFOA and PFOS beyond what
would already be cleaned up from the list of over 800 existing
hazardous substances would be tempered. See J.A. 554.

Further, EPA considered and rejected the Chamber of
Commerce’s data on this point, stating that the study
commissioned by the Chamber of Commerce had relied on

“discussions with industry rather than empirical data” for
developing its probability distributions and had relied on “30-
year-old data” for the basis of its cost estimates. J.A. 688, 213.
In addition, the study “conflate[d] costs to address PFOA and
PFOS contamination” at sites on the National Priorities List
“with costs attributable to designating PFOA and PFOS as
hazardous substances[,]” overlooking that the PFOA and PFOS
often have to be cleaned up anyhow as pollutants or
contaminants. J.A. 688. Plus even if EPA adds a site to the
National Priorities List, that “does not mean that any remedial
or removal action will be taken.” J.A. 688.

In short, EPA fairly considered the Chamber of
Commerce’s proposals and reasonably rejected them based in
part on its factfinding and experienced judgment. There is
nothing arbitrary or capricious about that. See National
Wildlife Fed’n, 286 F.3d at 563 (“The court should not
undertake its own economic study, but must uphold the
regulations if EPA has established in the record a reasonable
basis for its decision.”) (quotation marks omitted); Mississippi
Comm’n on Env’t Quality v. EPA, 790 F.3d 138, 150 (D.C. Cir.
2015) (per curiam) (deferring “to the EPA’s evaluation of
scientific data within its technical expertise”) (quotation marks
omitted).

Finally, Petitioners argue that EPA failed to account for
the addition of sites to the National Priorities List due to the
presence of only PFOA and PFOS and no other hazardous
substances. Pet’rs’ Opening Br. 52.

EPA considered that argument and drew a different
conclusion based on the record before it. It estimated that an
average of 10.9 new sites would be investigated for addition to
the National Priorities List each year. J.A. 561. EPA then
noted that at non-federally owned sites on the National

Priorities List, only 5.5% contained a single hazardous
substance, which reduces materially Petitioners’ concern about
independent costs stemming from PFOA/PFOS-only sites.
J.A. 509. EPA’s cost analysis also explained that “the
establishment of new NPL sites with PFOA/PFOS
contamination” would be “limit[ed]” because the national
production of these chemicals has “largely been phased out[.]”
J.A. 564 n.258. That reasoned review of record evidence and
the agency’s real-world experience adequately explain why
EPA concluded that listing PFOA and PFOS would not
dramatically increase its estimate of cleanup costs for the sites
(if any) with only PFOA and PFOS contamination. Petitioners’
disagreement and desire for a different approach does not
render EPA’s conclusions arbitrary or capricious.

Petitioners next argue that EPA made an arbitrarily low
estimate of the cleanup costs at sites not listed on the National
Priorities List. Pet’rs’ Opening Br. 54. They argue those costs
should have been higher because there are so many more
contaminated sites than are currently listed and because there
may be enforcement actions by entities other than the federal
government. Id. at 54–55.

The record supports EPA’s judgment.

First, EPA reasonably estimated the number of sites not on
the National Priorities List where it anticipated pursuing
enforcement actions and adequately explained its reasoning.
EPA estimated the number of PFOA and PFOS contamination
sites based on data tracked by companies that participated in a
voluntary Stewardship Program to phase out the manufacture
of PFAS more generally. J.A. 541. It then filtered for “sites
where the likelihood of PFOA/PFOS contamination is the

highest.” J.A. 541. That process identified 133 sites that would
qualify under EPA’s standards for higher levels of
contamination. J.A. 541. The agency then assumed that it
would pursue enforcement actions at only half of these sites,
and those actions would be spread out over time “[d]ue to
resource constraints[.]” J.A. 541–542. As a result, EPA
calculated costs for enforcement actions at 67 non-National
Priorities List sites over a four-year period. J.A. 542.

Petitioners see things differently. They cite a study that
EPA had relied on in another part of the Regulatory Impact
Analysis that estimated 57,412 sites that likely were
contaminated with PFOA and PFOS, making EPA’s estimates
“far too low[.]” Pet’rs’ Opening Br. 55 (citing J.A. 314).

EPA reasonably rejected Petitioners’ count of
contaminated sites. Their estimate was for sites contaminated
with any PFAS, which sweeps in “over 9,000 chemicals[,]”
J.A. 592, rather than just the two at issue here—PFOA and
PFOS.

Given that glaring flaw in Petitioners’ numbers, EPA
reasonably relied instead on the remedial site investigations of
other hazardous substances to reach its estimated 133
qualifying sites. J.A. 542–543. Contrast Pet’rs’ Opening Br.
56. EPA explained that it selected a low-end and high-end
estimate based on that historical data. J.A. 543. That was
reasonable given that there is no indication in the record that
PFOA and PFOS exposures would be outliers as to frequency
compared to the more than 800 already-existing hazardous
substances.

Further, Petitioners’ argument incorrectly assumes that all
contaminated sites are going to face cleanup actions and
resulting enforcement actions against responsible parties.

Instead, EPA assumed that it would pursue investigations “at
approximately half” of the estimated 133 qualifying sites. J.A.
541. There is little question that funding constraints limit
EPA’s ability to take enforcement actions. See J.A. 542. EPA
estimated that “[d]ue to resource constraints,” and based on
“historical patterns of PFOA/PFOS production and use in the
U.S.[,]” it planned to begin enforcement actions at only sixteen
to seventeen sites not on the National Priorities List per year.
J.A. 541–542.

Petitioners briefly argue that EPA acted arbitrarily and
capriciously in “assum[ing]” cleanup would only be initiated
by the federal government. Pet’rs’ Opening Br. 56. To the
contrary, EPA acknowledged that “states may use their own
authorities, if available, to require investigations, site
characterizations, or further response including cleanup.” J.A.
540. EPA then reasonably declined to include a cost estimation
for these cleanups in its cost-benefit analysis given the
uncertainty over state laws and whether and when States would
unilaterally pursue such cleanups. J.A. 540–541. Given that
the Designation is a federal regulation interpreting a federal
statute and overseen by a federal agency, it was reasonable for
EPA to refrain from trying to predict how state laws might or
might not affect the independent actions of all 50 States and
other jurisdictions.

Lastly, to the extent Petitioners want costs to include
indemnification actions by private parties seeking to hold other
private parties accountable for the costs of cleanup, they seek
to double count expenses because EPA already accounted for
that indemnification cost when it allocated cleanup costs to the
original polluter. The mere shifting of costs from one private
party to another does not create an additional set of costs.

Petitioners next attack EPA’s estimate of cleanup costs at
federal facilities. They argue that the agency put too much
stock into voluntary actions by the federal government that
EPA assumed would be undertaken even absent the
Designation. Pet’rs’ Opening Br. 57.

While EPA’s analysis was reasonably explained, J.A.
569–572, and based on data from ongoing cleanup efforts by
the Department of Defense, see J.A. 464–468, 569–572, we
also note that any miscalculation in this regard would have no
effect on Petitioners. This issue concerns the federal
government’s expenditure of its own funds to clean up its own
sites due to hazardous exposures caused by its own activities.
Petitioners nowhere explain how they would be affected, let
alone prejudiced, by any calculation errors on this front. See
Prohibition Juice Co. v. United States Food & Drug Admin.,
45 F.4th 8, 24 (D.C. Cir. 2022); 5 U.S.C. § 706 (requiring
reviewing courts to take “due account...of the rule of
prejudicial error”).

Petitioners next take issue with EPA’s treatment of costs
to certain industries, arguing that EPA ignored the costs of the
Designation to the waste management sector, the construction
industry, and the recycled materials industry. Pet’rs’ Opening
Br. 59–63.

EPA, though, acknowledged that industries like waste
management and construction historically have used PFOA
and PFOS, see J.A. 501–502, and spent several paragraphs
analyzing possible costs at wastewater treatment plants and
landfills that might contain sludge with PFOA and PFOS, see

J.A. 502–503. The agency then addressed the concerns
expressed in these industries’ comments about incurring
unlimited third-party liability for PFOA and PFOS
contamination of which they were not aware. See J.A. 233–
235, 330, 339–341; Designation, 89 Fed. Reg. at 39,160–
39,162. EPA reiterated CERCLA’s limitations on liability,
including for “situations in which the release or threat of
release of a hazardous substance was caused by an act of God,
an act of war, or an act or omission of a third party[,]” and for
entities that add only a “de minimis” or “de micromis” amount
to a release. Designation, 89 Fed Reg. at 39,169; see id. at
39,175, 39,179–180, 39,183. EPA also noted that the law
already requires certain reporting requirements for waste
management companies handling toxic chemicals, 42 U.S.C.
§ 11023; 40 C.F.R. pt. 372). Designation, 89 Fed Reg. at
39,175.

In that way, EPA reasonably grappled with Petitioners’
concerns. Reasoned decisionmaking does not require EPA to
undertake a deep-dive, individualized cost-benefit analysis of
indirect impacts for every single potentially affected industry.
See Cigar Ass’n of America v. FDA, 5 F.4th 68, 76 (D.C. Cir.
2021) (“[A]ppellants cite no authority for the proposition that
FDA needed to consider the benefits of premarket review
specifically for each industry or product affected by the [final]
Rule.”).

Moving on from cost calculations, Petitioners challenge
EPA’s calculation of the benefits of listing PFOA and PFOS as
hazardous substances. Pet’rs’ Opening Br. 53, 64.

Petitioners’ central objection is that EPA treated certain
costs as benefits by considering CERCLA’s shifting of costs

from taxpayers to private industry to be a benefit, rather than
recognizing that those costs will be imposed on private
industry. Pet’rs’ Opening Br. 64.

We reject Petitioners’ characterization. EPA’s Regulatory
Impact Analysis and the Designation did not reclassify costs as
benefits. Rather, EPA “recognize[d] that designation will
result in economic costs borne by PRPs [private parties]” and
“acknowledge[d] that the costs parties expend to clean up
PFOA and PFOS is a burden for them.” Designation, 89 Fed.
Reg. at 39,164. EPA then explained that these costs would
otherwise be borne by taxpayers, and that the transfer of these
costs from taxpayers to polluting companies was an
“advantage” of the Designation. Id.; see also id. at 39,152; J.A.
551–552. Transferring costs, EPA reasoned, would free up
Superfund dollars to address sites that EPA otherwise could not
address, resulting in benefits to the public. Designation, 89
Fed. Reg. at 39,153; J.A. 534, 547. EPA reasonably
determined that placing the burden of cleanup on “those
responsible for significant contamination represents an
improvement in social welfare as a result of the rule.”
Designation, 89 Fed. Reg. at 39,152. EPA’s reasoning is
consistent with CERCLA’s objectives to promote “timely
cleanup” and “ensure that the costs of such cleanup efforts [are]
borne by those responsible for the contamination.” Atlantic
Richfield Co., 140 S. Ct. at 1345 (quotation marks omitted). In
sum, EPA acknowledged the private sector’s costs, but it also
reasonably concluded that the transfer of costs from taxpayers
to polluters was an advantage of the Designation. That
approach was not arbitrary and capricious.

Petitioners also suggest that EPA must “consider whether
the purported health benefits of cleaning up PFOA and PFOS
could be obtained through less costly means.” Pet’rs’ Opening
Br. 64. Petitioners propose “providing alternative water” to

populations whose water sources are contaminated with PFOA
and PFOS. Id.

Some alternative solutions are so patently unadministrable
that EPA need not directly address them. See Farmers Union
Cent. Exch., Inc. v. FERC, 734 F.2d 1486, 1511 n.54 (D.C. Cir.
1984) (“Agency action ‘cannot be found wanting simply
because the agency failed to include every alternative device
and thought conceivable by the mind of man * * * regardless
of how uncommon or unknown that alternative may have
been.’”) (quoting Vermont Yankee Nuclear Power Corp. v.
NRDC, Inc., 435 U.S. 519, 551 (1978)). Providing bottled
water and bringing in and perpetually refilling water tanks for
every single person in scores of communities for decades—or
however much longer these two forever chemicals remain—
fails the common-sense test. Nor does that proposal address
the distinct environmental harms from the continuing presence
of PFOA and PFOS.

Petitioners’ final arbitrary and capricious argument is that
EPA violated the Regulatory Flexibility Act by excluding
indirect costs from its accounting of the Designation’s impact
on small businesses. Pet’rs’ Opening Br. 65–66. That
argument fares no better than its predecessors.

The Regulatory Flexibility Act, as amended by the Small
Business Regulatory Enforcement Fairness Act of 1996, 5
U.S.C. § 601 et seq., “is intended to evoke commentary from
small businesses about the effect of the rule on their activities,
and to require agencies to consider the effect of a regulation on
those entities.” Cement Kiln Recycling Coal. v. EPA, 255 F.3d
855, 868 (D.C. Cir. 2001) (per curiam). At the same time, an
agency need not undertake a lengthy analysis “if it certifies

‘that the rule will not, if promulgated, have a significant
economic impact on a substantial number of small entities.’”
Id. (quoting 5 U.S.C. § 605(b)).

Petitioners do not challenge EPA’s calculation of direct
costs for small businesses, but argue instead that EPA failed to
consider indirect costs associated with the Designation, such as
potential future liability for cleanup actions, which they argue
would constitute “the lion’s share of costs[.]” Pet’rs’ Opening
Br. 66.

The Regulatory Flexibility Act, however, does not extend
to indirect effects on small businesses, at least where, as here,
those effects are contingent on multiple intervening and
uncertain events. See Cement Kiln, 255 F.3d at 869 (“[T]his
court has consistently rejected the contention that the RFA
applies to small businesses indirectly affected by the regulation
of other entities.”); Mid-Tex Elec. Co-op., Inc. v. FERC, 773
F.2d 327, 343 (D.C. Cir. 1985) (“Congress did not intend to
require that every agency consider every indirect effect that any
regulation might have on small businesses in any stratum of the
national economy.”).

By its terms, the Regulatory Flexibility Act requires
agencies to consider “the projected reporting, recordkeeping
and other compliance requirements of the rule, including an
estimate of the classes of small entities which will be subject to
the requirement and the type of professional skills necessary
for preparation of the report or record[.]” 5 U.S.C. § 604(a)(5).

Those requirements capture the direct reporting
requirements that EPA evaluated, Designation, 89 Fed. Reg. at
39,184–39,185; J.A. 421, but do not extend to Petitioners’
perceived downstream risk of liability, which depends upon
multiple intervening decisions, analyses, reviews, and

opportunities for public input. See Section III.C., infra. That
leaves several more opportunities for EPA to consider site
investigation and cleanup costs borne by small businesses if
and when those costs arise. See 42 U.S.C. § 9605(a) (requiring
notice and comment rulemaking, which triggers a Regulatory
Flexibility Act analysis, 5 U.S.C. § 604(a), for sites to be added
to the National Priorities List, after which those sites may face
remedial action); see also 42 U.S.C. § 9605(a)(7) (requiring
that EPA develop “means of assuring that remedial action
measures are cost-effective”); 40 C.F.R. § 300.430(e)(7)(iii),
(9)(iii) (requiring the consideration of cost-effective
alternatives for remedial actions).

Petitioners separately claim that the Designation is
arbitrary and capricious because EPA assertedly did not
“carefully assess[] and does not understand” the “severe
consequences” this Designation will have. Pet’rs’ Opening Br.
67. According to Petitioners, “[t]hese uncertainties included
(1) where PFOA and PFOS are located, and in what quantities;
(2) what economic costs the Final Rule will impose, and how
parties will address contamination; and (3) unintended
consequences of designation, including on real estate
transactions.” Id. at 67–68.

EPA fully acknowledged that uncertainties exist in
regulating PFOA and PFOS as hazardous substances. See, e.g.,
Designation, 89 Fed. Reg. at 39,129 (“Every site is unique and
the extent of action necessary to mitigate risks depends on
many factors, which leads to uncertainties regarding response
activities and associated costs.”); id. at 39,150 (“[T]here is
considerable uncertainty regarding the cost of health burdens
that may result from exposure to PFOA or PFOS, and
associated cost savings from reducing the incidence of these

burdens because of designation.”); id. (“[T]here remains
uncertainty concerning the location and number of sites that
will be identified as needing remediation and the extent of
contamination at those sites. There is also uncertainty
regarding the potential incremental increase in cost (if any) of
addressing PFOA or PFOS at a site along with other
[Contaminants of Concern] present.”); id. at 39,159 (“EPA
assessed potential disadvantages of designation and weighed
those against the advantages. The disadvantages include * * *
the potential for uncertainty.”).

As EPA explained in the Designation, the central reason
that these uncertainties exist at the initial designation stage is
that “CERCLA response actions are discretionary, contingent,
and site-specific determinations.” Designation, 89 Fed. Reg.
at 39,149–39,150; see also id. at 39,169 n.65 (“EPA * * * only
responds to those releases that pose unacceptable risk to human
health and the environment. Even then, EPA may assess
relative risk among releases to determine which releases should
be prioritized for investigation and, potentially, clean up.”). As
a consequence, numerous additional regulatory steps must
occur before any liability ever attaches to a responsible party.

Consider, for example, the case of a new site that requires
remedial action. “[R]emedial action” involves a complex and
lengthy cleanup process for sites that pose particularly serious
risks to human health and the environment. 42 U.S.C.
§ 9601(24); J.A. 447–448.

Because EPA conducts remedial actions only at sites listed
on the National Priorities List (absent limited circumstances,
such as a special agreement with the polluting party, which
would require a willing counterparty and the negotiation of

party- and site-specific terms), see J.A. 448 & n.81, EPA must
first proceed through that extensive listing process. And that is
just the beginning of the contingent steps before any
responsible party might receive a bill for cleanup costs.

For a site even to be considered for the National Priorities
List, it has to:

(1) score above a certain threshold on CERCLA’s Hazard
Ranking System, which “assesses the relative degree of
risk to human health and the environment posed by sites
and facilities subject to review[,]” 42 U.S.C. § 9605(c)(1);
40 C.F.R. § 300.425(c)(1);

(2) be designated by a State “as its highest priority” site for
cleanup, 40 C.F.R. § 300.425(c)(2); or

(3) be both:

(a) categorized by EPA as “pos[ing] a significant
threat to public health” and as a site for which
remedial action “will be more cost-effective” than a
removal action, and

(b) the subject of a “health advisory” issued by the
Agency for Toxic Substances and Disease Registry,
id. § 300.425(c)(3).

Because of those factors, site placement on the National
Priorities List is never certain. EPA reported that it has placed
on the List “only about 3 percent of the 53,400 sites assessed
since the program’s beginning in 1980.” Designation, 89 Fed.
Reg. at 39,138.

And even when EPA decides to place a site on the List, it
must go through notice and comment rulemaking, which itself
could derail a proposed listing. 42 U.S.C. § 9605(a)(8)(A); see
also Eagle-Picher Indus., Inc. v. EPA, 759 F.2d 905, 910 (D.C.
Cir. 1985) (describing the listing process).

Those few sites that make it to the National Priorities List
must then undergo a remedial site evaluation, as required by
the National Contingency Plan. See 42 U.S.C. § 9607(a)
(limiting liability to removal and remedial actions “not
inconsistent with the national contingency plan”); 40 C.F.R.
§ 300.420 (listing requirements for remedial site evaluations).

There is still more. Even if the site satisfies the conditions
of the National Contingency Plan, EPA must then develop a
remedial action plan. See 40 C.F.R. §§ 300.430, 300.435. As
part of that process, EPA is required to compare alternative
options for cleanup and to assess costs, including direct and
indirect capital costs, annual operation and maintenance costs,
and the net present value of the costs. Id. § 300.430(e)(9)(iii).
CERCLA explicitly mandates that EPA “assur[e] that remedial
action measures are cost-effective[.]” 42 U.S.C. § 9605(a)(7).

EPA must then undertake a second notice and comment
period to approve its proposed remedial plan. See 42 U.S.C.
§ 9617(a).

Only after all that will questions of liability for a
responsible party arise, 42 U.S.C. § 9607, and even then,
financial costs may be allocated among multiple responsible
parties, see Burlington N. & Santa Fe Ry. Co. v. United States,
556 U.S. 599, 614–615 (2009) (explaining how joint-and-
several liability and apportionment apply to CERCLA
tortfeasors).

As an alternative to the listing and remedial action route,
EPA might conclude that a removal action is called for. Unlike
a remedial action, a removal action is a quicker “emergency
response[]” stopgap measure for smaller-scale chemical
releases. J.A. 447; see 42 U.S.C. § 9601(23). Though removal
actions are generally shorter term and less costly than remedial
actions, EPA still must go through several regulatory steps
before questions of liability arise.

First, the National Contingency Plan requires EPA to
determine that “there is a threat to public health or welfare of
the United States or the environment” before it can undertake
a removal action. 40 C.F.R. § 300.415(b)(1).

To determine whether there is such a threat, EPA must
consider a list of seven non-exhaustive factors including actual
or potential “exposure to nearby human populations,”
“contamination of drinking water supplies[,]” “[w]eather
conditions[,]” “[t]hreat of fire or explosion[,]” and “[t]he
availability of other appropriate federal or state response
mechanisms to respond to the release[.]” 40 C.F.R.
§ 300.415(b)(2).

Then, if EPA determines that an extensive removal action
is needed—that is, an action requiring six months or more of
planning—additional regulatory steps kick in. 40 C.F.R.
§ 300.415(n)(4). They include the publication of notice “in a
major local newspaper of general circulation” and an
opportunity for public comment thereafter. Id.
§ 300.415(n)(4)(ii), (iii). EPA also must conduct “an
engineering evaluation/cost analysis” of the proposed action.
Id. § 300.415(b)(4)(i).

Finally, for both removal and remedial actions, there are
additional statutory layers of protection before a responsible
party faces liability.

First, a party has to qualify as a “[c]overed person[]” under
42 U.S.C. § 9607, which limits liability to those who (1) owned
or operated a facility with one or more hazardous substances at
the time of release or cleanup, or (2) arranged for, conducted,
or owned a vehicle used for the transportation or disposal of the
hazardous substance. 42 U.S.C. § 9607(a); see also Burlington
N. & Santa Fe Ry. Co., 556 U.S. at 610 (“[T]he question
whether § 9607(a)(3) liability attaches [based on the “[c]overed
person[]” designation] is fact intensive and case specific, [and]
such liability may not extend beyond the limits of the statute
itself.”).

Second, CERCLA provides complete defenses to liability
when a release was caused by “an act of God” or “an act or
omission of a third party[,]” so long as the defendant has
“exercised due care” and taken “precautions against
foreseeable” risks. 42 U.S.C. § 9607(b).

Third, the government must show that all costs imposed
on the polluter are “not inconsistent with the national
contingency plan[,]” 42 U.S.C. § 9607(a), an extensive series
of regulations that includes mandatory considerations of cost
efficiency, see 40 C.F.R. pt. 300; see also, e.g., id.
§ 300.415(b)(4) (requiring the creation of “an engineering
evaluation/cost analysis”); id. § 300.425(c)(3)(iii) (requiring
that “EPA anticipate[] that it will be more cost-effective to use
its remedial authority than to use removal”); id.
§ 300.430(e)(7)(iii) (requiring a feasibility study that includes

“[t]he costs of construction and any long-term costs” of
alternatives).

Fourth, CERCLA directs EPA to “minimize litigation”
and prioritize settlements over enforcement actions. 42 U.S.C.
§ 9622(a). CERCLA provides that, “[w]henever practicable
and in the public interest,” EPA must pursue settlement with a
responsible party. Id. Any settlement agreements also must be
“in the public interest and consistent with the National
Contingency Plan[.]” Id.

* * * * *

All of those uncertainties and contingencies make
forecasting liability costs exceptionally difficult upfront. But
those same steps also ensure that remedial and recovery actions
are undertaken only upon thoroughgoing site-specific
consideration and review by EPA, a weighing of the relative
harms and benefits of action, and consideration of the statutory
limitations on liability. Given all that, Petitioners’ worry that
listing PFOA and PFOS as hazardous substances will lead
ineluctably to significant liability is misplaced.

Further, EPA explained that the Designation’s impact on
regulated parties can be mitigated, at least in part, by EPA’s
enforcement discretion and CERCLA’s explicit liability
limitations. See Designation, 89 Fed. Reg. at 39,129–39,130,
39,138–39,139, 39,169 (citing 42 U.S.C. § 9607(a), (b)). In
addition to CERCLA’s limitations on liability, EPA cited
several “de minimis” and “de micromis” protections for
polluters who contributed small amounts to a much larger
release, id. at 39,160–38,161 (citing 42 U.S.C. § 9607(o)),
including an expedited settlement process, id. at 39,130 n.17
(citing 42 U.S.C. § 9622(g)(1)).

EPA’s discussion of liability limitations also disposes of
Petitioners’ complaint that EPA failed to consider uncertain
costs associated with real estate transactions. EPA did not
conduct an individualized cost analysis of the Designation’s
impact on the real estate market. But EPA is not required to
“respond to every comment, or to analyze every issue or
alternative raised by the comments[.]” Sherley v. Sebelius, 689
F.3d 776, 784 (D.C. Cir. 2012) (formatting modified). Because
EPA discussed more generally the limitations on liability for
those who are not primarily responsible for a release, see
Designation, 89 Fed. Reg. at 39,139, as well as “innocent
landowners” that are protected from liability if they have “no
knowledge of the contamination at the time of purchase,” id. at
39,161 (citing 42 U.S.C. § 9601(35)), which would include
individuals who purchase a home polluted by a prior owner,
EPA adequately addressed that concern.

Indeed, few if any exercises of regulatory enforcement
discretion are roped around with so many required layers of
analysis, protections, and limitations. Experience bears that
out. PFOA and PFOS are two drops in a bucket of the over 800
hazardous substances under CERCLA, 40 C.F.R. § 302.4 table,
including hundreds that have been on the list since CERCLA
was enacted in 1980. See, e.g., Air Pollution Prevention and
Control List of Hazardous Air Pollutants, 36 Fed. Reg. 5,931,
5,931 (March 31, 1971) (designating asbestos, beryllium, and
mercury as hazardous air pollutants under Section 112 of the
Clean Air Act, which is incorporated by CERCLA’s list of
designated hazardous substances, 42 U.S.C. § 9601(14));
Designation of Hazardous Substances, 43 Fed. Reg. 10,474,
10,481–10,486 (March 13, 1978) (same for acetic acid,
ammonia, arsenic disulfide, butyric acid, calcium cyanide,
chlorine, ferric sulfate, lead acetate, phosphorus, and hundreds
of others as hazardous substances under Section 311(b)(2)(A)
of the Federal Water Pollution Control Act). Petitioners have

come forward with no evidence that those responsible for the
presence of hazardous substances at a site have been unfairly
saddled with liability or that the statute’s operation has
hamstrung industry.

In sum, having adequately considered and reasonably
explained its decision to regulate at this initial stage even in the
face of acknowledged uncertainties, EPA made a reasoned
decision on the record before it in designating the forever
chemicals PFOA and PFOS as hazardous substances.

For the foregoing reasons, the petitions for review are
denied.

So ordered.

Chamber of Commerce of the United States of America v. Environmental Protection Agency

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