Court Opinion

ID: 9393926
Source: CourtListenerOpinion
Date Created: 2023-05-11 17:01:38.005289+00
Date Added: 2024-06-11T17:18:56.193738
License: Public Domain

FOR PUBLICATION

  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT

DARLENE HOLLINS; CHRISTIAN                No. 21-56031
LEMUS; ALAIN MICHAEL;
MARIE ANGELINE FALCONE,                     D.C. No.
Individually and on Behalf of All
                                         2:19-cv-05526-
Others Similarly Situated,
                                           SVW-GJS
              Plaintiffs-Appellants,
and
                                            OPINION

ANGELA DIAMOS,
              Plaintiff,
v.

WALMART INC.;
INTERNATIONAL VITAMIN
CORPORATION,
              Defendants-Appellees.

      Appeal from the United States District Court
          for the Central District of California
      Stephen V. Wilson, District Judge, Presiding
2                    HOLLINS V. WALMART, INC.

          Argued and Submitted November 22, 2022
                    Pasadena, California

                       Filed May 11, 2023

     Before: Danny J. Boggs,* Kim McLane Wardlaw, and
               Sandra S. Ikuta, Circuit Judges.

                    Opinion by Judge Ikuta;
               Partial Dissent by Judge Wardlaw

                          SUMMARY **

           Federal Food, Drug, and Cosmetic Act

    The panel affirmed the district court’s order granting
summary judgment for Walmart Inc. in a consumer class
action alleging that Walmart’s product, Spring Valley
Glucosamine Sulfate, contained glucosamine hydrochloride,
not glucosamine sulfate or glucosamine sulfate potassium
chloride, and that the plaintiffs were allegedly damaged by
the misleading labeling.
   The Federal Food, Drug, and Cosmetic Act (“FDCA”)
prohibits the misbranding of any food. A food is deemed to
be misbranded if it meets any of the definitions in 21 U.S.C.

*
  The Honorable Danny J. Boggs, United States Circuit Judge for the
U.S. Court of Appeals for the Sixth Circuit, sitting by designation.
**
  This summary constitutes no part of the opinion of the court. It has
been prepared by court staff for the convenience of the reader.
                  HOLLINS V. WALMART, INC.                 3

§ 343. Section 343(q) includes a subsection specific to
dietary supplements. To implement this subsection, the
Food and Drug Administration (“FDA”) promulgated
regulations governing the nutrition labeling of dietary
supplements. See 21 C.F.R. § 101.36. Dietary ingredients
such as glucosamine sulfate potassium chloride, for which
the FDA has not established a Reference Daily Intake or
Daily Reference Values, are governed by § 101.36(b)(3),
which provides that such dietary ingredients “shall be
declared by their common or usual name.” Compliance with
this requirement is determined in accordance with specified
testing protocols. The FDCA preempts specified state
requirements relating to food labeling.
    The named plaintiff, Darlene Hollins, alleged that she
and other consumers were damaged because “they paid for a
product that they would not have purchased had it truthfully
disclosed that it did not contain Glucosamine Sulfate.” The
second amended complaint claimed violations of the
California Consumers Legal Remedies Act, the California
Unfair Competition Law, the California False Advertising
Law, unjust enrichment, restitution, and breach of
warranty. The district court held that the methods used by
Hollins’ expert witness, Dr. Neil Spingarn, raised Daubert
concerns and were not reliable and appropriate under 21
C.F.R. § 101.9(g)(2) for determining whether Walmart’s
product was mislabeled. The district court concluded that
Walmart had carried its burden of showing that Hollins’s
state-law claims were preempted by federal law.
    Hollins contended that her state-law mislabeling claim,
which would require the state to impose the rule that a blend
of glucosamine hydrochloride and potassium sulfate cannot
be labeled glucosamine sulfate or glucosamine sulfate
potassium chloride, is not preempted because such a rule is
4                  HOLLINS V. WALMART, INC.

identical to the federal rule. The panel held that Hollins’s
claim that Walmart’s product was mislabeled due to being a
blend would allow a state to impose a different labeling
requirement of Walmart’s product than is imposed § 343(q),
and is therefore preempted.
    Hollins argued that her claim would not allow a state to
impose a labeling requirement on Walmart’s product
different from that imposed by § 343(b). She argued that a
label can violate § 343(b) even if the label uses the product’s
“common or usual name,” as determined by federal testing
requirements under § 343(q), because such testing
requirements apply only to the information provided in the
nutrition panel. The panel disagreed. Section 343(s)(2)(B)
permits Walmart to label its dietary supplement with the
name of its active ingredient, and the “common and usual”
name of that ingredient may be determined pursuant to
federal testing requirements. The panel held that Hollins’s
proposed rule to the contrary was preempted. The holding
in Durnford v. MusclePharm Corp., 907 F.3d 595 (9th Cir.
2018), did not provide otherwise. Nothing in Durnford
suggested its analysis applied only to the nutrition
panel. This case is governed by Durnford’s holding that the
manufacturer’s method for determining the amount of
protein in the supplement was authorized by regulation and
therefore preempted Hollins’s proposed state-law rule. In
addition, the panel rejected the dissent’s reliance on Hawkins
v. Kroger Co., 906 F.3d 763 (9th Cir. 2018), and held that
Hawkins was inapposite here.
    The panel concluded that Hollins’s claims were
preempted, and Walmart was entitled to judgment as a
matter of law.
                    HOLLINS V. WALMART, INC.                   5

    Judge Wardlaw dissented in part. In her view, Hollins
was not required to comply with the FDA’s testing
requirements with respect to her claims outside of the
nutrition facts panel. Challenges to the label under 21
U.S.C. § 343(q) are distinct from those to the nutrition facts
panel under 21 U.S.C, § 343(q), such that the 21 C.F.R. §
101.9(g) federal testing requirements do not apply to the
label outside of the nutrition panel, and, therefore, these state
law claims are not preempted by federal law, and can
proceed. She wrote that the majority opinion misapplied
Durnford, and ran counter to the presumption against
preemption.

                         COUNSEL

Matthew Insley-Pruitt (argued), Carl L. Stine, and Philip M.
Black, Wolf Popper LLP, New York, New York; Jonathan
M. Rotter and Danielle L. Manning, Glancy Prongay &
Murray LLP, Los Angeles, California; for Plaintiffs-
Appellants.

Jean-Claude André (argued) and Jennifer A. Jackson, Bryan
Cave Leighton Paisner LLP, Santa Monica, California; A.
Elizabeth Blackwell, Darci F. Madden, Stefani L.
Wittenauer, and Steven J. Alagna, Bryan Cave Leighton
Paisner LLP, St. Louis, Missouri; Simren K. Gill, Law
Offices of Simren K. Gill, Fresno, California; Jon Pfeiffer I,
Pfeiffer FitzGibbon & Ziontz LLP, Santa Monica,
California; for Defendants-Appellees.
6                     HOLLINS V. WALMART, INC.

                              OPINION

IKUTA, Circuit Judge:

    Darlene Hollins and three other consumers brought a
class-action lawsuit against Walmart Inc. and International
Vitamin Corporation under California law. 1         In her
complaint, Hollins alleged that Walmart’s product, “Spring
Valley     Glucosamine      Sulfate,”   manufactured    by
International Vitamin Corporation, contained glucosamine
hydrochloride, not glucosamine sulfate or glucosamine
sulfate potassium chloride, and claimed she was damaged by
the misleading labeling. We hold that Hollins’s claims are
preempted because they seek to impose state labeling
requirements that are not identical to the requirements of
applicable federal regulations. Therefore, we affirm the
district court’s order granting summary judgment for
Walmart.
                                    I
    We begin by providing the legal background. The
Federal Food, Drug, and Cosmetic Act (FDCA), 21 U.S.C.
§§ 301–399i, governs (among other things) “fixing and
establishing for any food, under its common or usual name
so far as practicable, a reasonable definition and standard of
identity.” 21 U.S.C. § 341. The Secretary of Health and
Human Services has authority to promulgate regulations to
enforce the FDCA, 21 U.S.C. § 371(a), and has delegated
this authority to the Food and Drug Administration (FDA).
See FDA v. Brown & Williamson Tobacco Corp., 529 U.S.

1
 To avoid confusion, we refer to the consumer plaintiffs in this action as
Hollins and refer to the defendants Walmart and International Vitamin
Corporation as Walmart.
                      HOLLINS V. WALMART, INC.                        7

120, 126 (2000).      We first describe the applicable
misbranding provisions of the FDCA and then turn to the
applicable preemption provisions.
                                  A
    The FDCA prohibits the “misbranding of any food.” 21
U.S.C. § 331(b). “[A] dietary supplement shall be deemed
to be a food within the meaning of [the FDCA].” Id.
§ 321(ff). A food is “deemed to be misbranded” if it meets
any of the definitions in 21 U.S.C. § 343.
    The parties focus on two of these definitions. First, a
food is misbranded “[i]f it is offered for sale under the name
of another food.” Id. § 343(b). For instance, the FDA has
indicated that labeling an item “red snapper” when it actually
consists of rockfish, “an economically inferior species,” is a
violation of § 343(b). 59 Fed. Reg. 4142, 4176 (proposed
Jan. 28, 1994).
    Second, a food is misbranded if its label does not bear
nutrition information that meets the requirements set forth in
21 U.S.C. § 343(q) and the regulations promulgated by the
FDA pursuant to this section. 2 Section 343(q)(1) lists the
nutrition information that must be included on the label,
including serving size, calories, the amount of specified
nutrients, and a list of nutrients specified by the FDA, while
§ 343(q)(2) authorizes the FDA to issue regulations
regarding additional nutrition information that must be
included. The FDA has promulgated regulations delineating

2
  “We refer to the product’s packaging as a whole as the ‘label.’”
Durnford v. MusclePharm Corp., 907 F.3d 595, 598 n.1 (9th Cir. 2018).
We refer to the format required by § 101.9(d) for certain nutritional
information as the “nutrition panel.” Id. The nutrition panel is part of
the label. Id.
8                 HOLLINS V. WALMART, INC.

the nutrition information that must be included and the
format for presenting the information to consumers. See 21
C.F.R. § 101.9(c), (d).
    Section 343(q) includes a subsection specific to dietary
supplements. See 21 U.S.C. § 343(q)(5)(F). This subsection
provides that a dietary supplement product “shall comply
with the requirements of [§ 343(q)(1) and (2)] in a manner
which is appropriate for the product and which is specified
in regulations” of the FDA, and lists the nutrition
information to be provided. Id.
    To implement this subsection, the FDA has promulgated
regulations governing the nutrition labeling of dietary
supplements.      See 21 C.F.R. § 101.36.        Under the
regulations, dietary ingredients such as glucosamine sulfate
potassium chloride, for which the FDA has not established a
Reference Daily Intake or Daily Reference Values, are
governed by § 101.36(b)(3), which provides that such
dietary ingredients “shall be declared by their common or
usual name.” Id. § 101.36(b)(3)(i). Compliance with this
“common or usual name” requirement is determined in
accordance with specified testing protocols. As explained in
the regulations,

       Compliance with [§ 101.36] will be
       determined in accordance with § 101.9(g)(1)
       through (g)(8), (g)(10), and (g)(11), except
       that the sample for analysis shall consist of a
       composite of 12 subsamples (consumer
       packages) or 10 percent of the number of
       packages in the same inspection lot,
                      HOLLINS V. WALMART, INC.             9

       whichever is smaller, randomly selected to be
       representative of the lot.

Id. § 101.36(f)(1).
     Under § 101.9(g)(2) (one of the sections referenced in
§ 101.36(f)(1) that is relevant to this case), 12 subsamples
must “be analyzed by appropriate methods as given in the
‘Official Methods of Analysis of the AOAC International,’
or, if no AOAC method is available or appropriate, by other
reliable and appropriate analytical procedures.” The AOAC
“is a comprehensive collection of chemical and
microbiological methods of analysis” which “have
undergone rigorous scientific review and validation to
determine the performance characteristics for the intended
analytical application and fitness for purpose.” 81 Fed. Reg.
33742, 33748–49 (May 27, 2016).
    If there is no AOAC official method available or
appropriate for a particular dietary supplement, the
manufacturer may use an alternative methodology. FDA,
Guidance for Industry: Nutrition Labeling Manual – A
Guide for Developing and Using Data Bases (1998), 1998
WL 34327548, at *15. An alternate method used “to support
a nutrient declaration value” must have “appropriate
validation” unless the method was previously validated by
collaborative studies. 58 Fed. Reg. 2079, 2109 (Jan. 6,
1993).     According to the FDA, validation means
“demonstrating performance characteristics such as
accuracy, precision, sensitivity, selectivity, limit of
detection, limit of quantitation, linearity, range, and
ruggedness, to ensure that results are meaningful.” FDA,
Guidelines for the Validation of Chemical Methods in Food,
Feed, Cosmetics, and Veterinary Products (3rd ed. 2019), at
4. Certified reference materials, which are reference
10                    HOLLINS V. WALMART, INC.

samples issued by an authoritative body to provide one or
more specified property values, are a tool used to validate
the accuracy of a test method. Id. at 6, 17; see also FDA,
Guidance for Industry: Nutrition Labeling Manual – A
Guide for Developing and Using Data Bases (1998), 1998
WL 34327548, at *16 (stating that determining the accuracy
of a new test method requires using “a material or a standard
with a certified concentration of the analyte being
measured”).
    Methods that are validated are often referred to as
“compendial” test methods. As defined in the FDCA, an
“official compendium” includes “the official United States
Pharmacopoeia [(USP)].” 21 U.S.C. § 321(j). The European
Pharmacopeia (EP) is a compendial standard recognized in
the European Union and observed by the United States. 3
    In sum, a dietary supplement such as glucosamine sulfate
potassium chloride is deemed misbranded if it is sold under
the name of a different food or dietary supplement, 21 U.S.C.
§ 343(b), or does not provide the “common or usual name”
of its dietary ingredient, 21 C.F.R. § 101.36(b)(3)(i), as
determined in accordance with a validated test method.

3
  The European Pharmacopeia “is the primary source of official quality
standards for medicines and their ingredients in Europe.” European
Pharmacopoeia,       11th      Edition,      www.edqm.eu/en/european-
pharmacopoeia-ph.-eur.-11th-edition. The United States is not a member
of the EP but has observer status. EUR-Lex, European Pharmacopoeia
(June         4,       2014),        https://eur-lex.europa.eu/EN/legal-
content/summary/european-pharmacopoeia-eur-lex.html. The European
Pharmacopoeia maintains a certified reference standard of glucosamine
sulfate potassium chloride.
                      HOLLINS V. WALMART, INC.                         11

                                   B
    The FDCA preempts specified state requirements
relating to food labeling. Two such preemption provisions
are relevant here. First, “no State or political subdivision of
a State may directly or indirectly establish under any
authority or continue in effect as to any food in interstate
commerce . . . any requirement for the labeling of food of
the type required by section 343(b) . . . of this title [requiring
that the food not be offered under the name of another food]
that is not identical to the requirement of such section.” 21
U.S.C. § 343-1(a)(3).
    Second, “no State or political subdivision of a State may
directly or indirectly establish under any authority or
continue in effect as to any food in interstate
commerce . . . any requirement for nutrition labeling of food
that is not identical to the requirement of section 343(q) of
this title [requiring certain nutrition information to be on the
food’s label].” Id. § 343-1(a)(4). 4
    A state law is “not identical to the requirement of” a
specified section if “the State requirement directly or
indirectly imposes obligations or contains provisions
concerning the composition or labeling of food
[that] . . . [a]re not imposed by or contained in the [FDCA or
applicable federal regulation] . . . or [d]iffer from those
specifically imposed by or contained in the applicable
provision” of the FDCA or applicable federal regulation. 21
C.F.R. § 100.1(c)(4). Because the FDCA “preempts state-
law requirements for claims about dietary supplements that

4
  Section 343-1(a)(4) applies to requirements that are “not identical to
the requirement[s] of [§] 343(q),” which sets forth requirements for the
“label or labeling” of food generally. Cf. Dissent at 31 (arguing that
§ 343-1(a)(4) applies only to information contained in a nutrition panel).
12                HOLLINS V. WALMART, INC.

differ from the FDCA’s requirements,” Dachauer v. NBTY,
Inc., 913 F.3d 844, 848 (9th Cir. 2019), “private plaintiffs
may bring only actions to enforce violations of ‘state laws
imposing requirements identical to those contained in the
FDCA.’” Kroessler v. CVS Health Corp., 977 F.3d 803, 808
(9th Cir. 2020) (citation omitted). Therefore, “a state-law
misbranding claim” that would allow “a state to impose
requirements . . . different from those permitted under the
FDCA . . . is preempted.” Durnford, 907 F.3d at 603. “[W]e
do not invoke any presumption against pre-emption” where,
as here, “the statute ‘contains an express pre-emption
clause.’” Puerto Rico v. Franklin Cal. Tax-Free Tr., 579
U.S. 115, 125 (2016) (quoting Chamber of Com. of U.S. v.
Whiting, 563 U.S. 582, 594 (2011)).
                             II
    We now turn to the facts of this case. In her second
amended complaint, Hollins asserted that Walmart’s product
labeled “Spring Valley Glucosamine Sulfate” contained
glucosamine hydrochloride, not glucosamine sulfate or
glucosamine sulfate potassium chloride. Hollins asserted
that glucosamine sulfate potassium chloride is comprised of
glucosamine, sulfate, potassium, and chloride bonded to
form a single crystal, but Walmart’s glucosamine sulfate
instead consists of a blend of glucosamine hydrochloride and
potassium sulfate. Hollins based this conclusion on tests of
13 bottles of Walmart’s product, using a test method called
Fourier-transform infrared spectroscopy (FTIR). According
to Hollins, the dietary supplement marketed by Walmart
contains glucosamine hydrochloride, and therefore cannot
                       HOLLINS V. WALMART, INC.                         13

be labeled either “glucosamine sulfate” or “glucosamine
sulfate potassium chloride.” 5
     According to the second amended complaint, although
glucosamine is sold in two commercial formulations,
glucosamine sulfate and glucosamine hydrochloride, only
glucosamine sulfate has demonstrated clinical effectiveness
for certain conditions, so consumers are willing to pay more
for this formulation. Therefore, Hollins claimed that she and
other consumers were damaged because “they paid for a
product that they would not have purchased had it truthfully
disclosed that it did not contain Glucosamine Sulfate.”
Based on these allegations, the second amended complaint
claimed violations of the California Consumers Legal
Remedies Act, the California Unfair Competition Law, the
California False Advertising Law, unjust enrichment,
restitution, and breach of warranty.
    In October 2020, Walmart moved for summary
judgment on the ground that Hollins’s claims were based on
a testing protocol that was different than the protocol
required by federal law, and her claims were therefore
preempted. Specifically, Walmart claimed that Hollins’s
testing methodology deviated from federal requirements
under 21 C.F.R. § 101.9(g), because it was not performed on
12 packages of Walmart’s product from the same lot at issue
and because Walmart’s product was tested by FTIR testing,

5
  At the time the lawsuit commenced, the label identified Walmart’s
product as “Glucosamine Sulfate,” and listed the active ingredient as
“Glucosamine Sulfate Potassium Chloride 1000mg (1 g).” During the
pendency of the lawsuit, the label was changed to identify Walmart’s
product as “Glucosamine Sulfate Potassium Chloride” and listed the
same active ingredient. Hollins does not attribute any significance to this
change and has forfeited any argument on that ground, contrary to the
dissent. Dissent at 27.
14                HOLLINS V. WALMART, INC.

rather than by the AOAC International Official Method
2005.01.
    The district court denied the motion, because Walmart
had not established that AOAC Method 2005.01 was the
appropriate method for determining whether Walmart’s
product was glucosamine sulfate potassium chloride or
glucosamine hydrochloride. The AOAC Method 2005.01 is
“[a]pplicable to the analysis of glucosamine in raw materials
and dietary supplements containing glucosamine sulfate
and/or glucosamine hydrochloride.” However, the district
court deemed it unclear whether the method was appropriate
for distinguishing between glucosamine sulfate (or
glucosamine sulfate potassium chloride) and glucosamine
hydrochloride. Nor had Walmart met its burden of showing
that Hollins’s test methodology was not “reliable and
appropriate.” Instead, the court granted Hollins’s discovery
request to obtain 12 samples from a single lot in order to
conduct testing in compliance with federal law, see 21
C.F.R. § 101.9(g)(2), for the purpose of establishing that
Walmart’s product was not glucosamine sulfate or
glucosamine sulfate potassium chloride.
    After Hollins obtained the 12 samples from the same lot
and conducted testing, the district court held an evidentiary
hearing. At the hearing, Hollins’s expert witness, Dr. Neil
Spingarn, testified that he tested 12 unopened bottles from
the same lot using FTIR, X-Ray Diffraction (XRD), and
Energy Dispersive X-Ray Spectroscopy (EDX). According
to Spingarn, the tests showed that Walmart’s product
contained a blend of glucosamine hydrochloride and
potassium sulfate, rather than a single crystal of glucosamine
sulfate potassium chloride.
                  HOLLINS V. WALMART, INC.                15

    On cross-examination, Spingarn agreed that the FDA
requires the use of a compendial test method to validate a
labeling claim. He agreed that the USP standard was a
compendial test method. He also agreed that either a single
crystal or a blend would satisfy the USP standards for
glucosamine sulfate potassium chloride, and therefore
Walmart’s product would qualify as glucosamine sulfate
potassium chloride under the USP method. Spingarn also
admitted that he had purchased the EP certified reference
standard of glucosamine sulfate potassium chloride, and had
confirmed that Walmart’s product was indistinguishable
from that standard. He argued, however, that the EP’s
certified reference standard was mislabeled because it was a
blend, not a single crystal.
    With respect to Spingarn’s three test methods (FTIR,
XRD, and EDX), Spingarn conceded that he had not
published his methods, submitted them for peer review, or
documented them in a standard operating procedure. He
agreed that his methods were neither validated nor accepted
by the FDA to validate label claims for either glucosamine
sulfate or glucosamine hydrochloride dietary supplements,
and were not considered compendial methods. Finally,
Spingarn conceded that he had not found (nor was he aware
of anyone finding) any product or material that met his
criteria of being a single crystal of glucosamine sulfate
potassium chloride rather than a blend.
    After the evidentiary hearing, the district court granted
Walmart’s summary judgment motion. The court concluded
that Spingarn’s methods raised Daubert concerns and were
not “reliable and appropriate” under 21 C.F.R. § 101.9(g)(2)
for determining whether Walmart’s product was mislabeled.
The court concluded that Walmart had carried its burden of
16                   HOLLINS V. WALMART, INC.

showing that Hollins’s state-law claims were preempted by
federal law. Hollins timely appealed.
                                 III
    We review de novo a district court’s grant of summary
judgment, Martinez v. City of Clovis, 943 F.3d 1260, 1269
(9th Cir. 2019), and “questions of preemption.” Silvas v.
E*Trade Mortg. Corp., 514 F.3d 1001, 1004 (9th Cir. 2008)
(citation omitted); see also Kroessler, 977 F.3d at 807.
    On appeal, Hollins argues that the district court erred in
holding that Walmart carried its burden of proving, as a
matter of law, that Hollins’s claims are preempted. Hollins
contends that her state-law mislabeling claim, which would
require the state to impose the rule that a blend of
glucosamine hydrochloride and potassium sulfate cannot be
labeled glucosamine sulfate or glucosamine sulfate
potassium chloride, is not preempted because such a rule is
identical to the federal rule. “FDCA preemption, like all
federal preemption, is an affirmative defense,” Durnford,
907 F.3d at 603 n.8 (citation omitted), as to which the
defendant bears the burden of proof. To prevail on summary
judgment, Walmart has to show that, as a matter of law,
Hollins’s proposed state rule would impose labeling
requirements different than those imposed by § 343(b) and §
343(q), and is therefore preempted. 6 See 21 U.S.C. § 343-
1(a)(3), (4).
    We begin with Hollins’s contention that her claim would
not impose a different labeling requirement on Walmart’s
product than is imposed by § 343(q). According to Hollins,
under § 343(q), a blended version of glucosamine sulfate

6
  Hollins does not invoke any other subsection of § 343 to support her
claim.
                     HOLLINS V. WALMART, INC.                       17

potassium chloride (such as Walmart’s product) may not be
identified on the label as glucosamine sulfate or glucosamine
sulfate potassium chloride, because such a label does not
meet the federal regulatory requirement that the ingredients
be declared by “their common or usual name,” 21 C.F.R. §
101.36(b)(3)(i). We disagree. A product’s “common or
usual name” is determined by testing using an AOAC
method, or “by other reliable and appropriate procedures.”
Id. § 101.9(g)(2). In an effort to establish that a blended
version of glucosamine sulfate potassium chloride does not
meet federal requirements, Spingarn used test methods
(FTIR, XRD, and EDX) that he conceded were not validated
or accepted by the FDA for use in this context. Instead of
supporting Hollins’s argument, Spingarn’s testing indicated
that Walmart’s product met the EP’s certified reference
standard for glucosamine sulfate potassium chloride, which
supports Walmart’s position that glucosamine sulfate or
glucosamine sulfate potassium chloride are the “common or
usual name” of the product under federal law. Moreover,
Spingarn conceded that the blended form of glucosamine
sulfate potassium chloride would satisfy the USP
compendial standard, another indication that Walmart was
using the “common or usual name” of the dietary
supplement on its label. See 60 Fed. Reg. 67194, 67201
(proposed Dec. 28, 1995) (stating that if a “dietary ingredient
is covered by an official compendium, FDA would expect
that the dietary ingredient’s common or usual name to be
drawn from that source”). 7 Although Spingarn argues that

7
 The dissent concedes that Hollins cannot prove the distinction between
glucosamine sulfate potassium chloride and glucosamine hydrochloride
with potassium sulfate “through a validated testing and sampling method
as required under 21 C.F.R. § 101.9(g)(2).” Dissent at 25, 27. The
dissent nevertheless argues that there is a distinction between these
18                    HOLLINS V. WALMART, INC.

the EP reference standard was itself mislabeled, this
allegation is irrelevant for purposes of determining what
federal law requires. In short, Hollins’s claim that
Walmart’s product was mislabeled due to being a blend
would allow a state to impose a different labeling
requirement on Walmart’s product than is imposed by
§ 343(q), and is therefore preempted. See 21 U.S.C. § 343-
1(a)(4).
     We next turn to Hollins’s argument that her claim would
not allow a state to impose a labeling requirement on
Walmart’s product different from that imposed by § 343(b).
In making this claim, Hollins argues that a blend of
glucosamine hydrochloride and potassium sulfate is
mislabeled if it is offered under the name of glucosamine
sulfate or glucosamine sulfate potassium chloride because
such a label offers a product “for sale under the name of
another food” in violation of the labeling requirements in §
343(b). Hollins argues that a label can violate § 343(b), even
if the label uses the product’s “common or usual name” as
determined by federal testing requirements under § 343(q),
see 21 U.S.C. § 101.9(g)(2), because such testing
requirements apply only to the information provided in the

formulations, based on diagrams taken from the National Institutes of
Health’s website. Dissent at 24, Appendix A. Because such diagrams
“were not part of the record before the district court and are not part of
the record before us,” Nevius v. Sumner, 852 F.2d 463, 470 (9th Cir.
1988), and because they shed no light on the molecular structure of the
glucosamine sulfate potassium chloride at issue here, they are irrelevant
to our analysis.
                     HOLLINS V. WALMART, INC.                       19

nutrition panel. 8 Hollins and the dissent rely on Durnford to
support this theory. Dissent at 25–27.
    We disagree. As explained above, Spingarn’s testing
and concessions indicated that under federal law,
glucosamine sulfate or glucosamine sulfate potassium
chloride are common or usual names for the blended
formulation of glucosamine sulfate. Logically, using the
“common or usual” name of a product to identify the product
on the label does not constitute offering that product for sale
“under the name of another food,” in violation of § 343(b).
Hollins cites nothing contrary to this common-sense
conclusion. Moreover, this conclusion is supported by the
labeling requirements in 21 U.S.C. § 343(s), which require a
dietary supplement to be labeled with the name of each
active ingredient (i.e., each ingredient “for use . . . to
supplement the diet,” id. § 321(ff)(1)(E)), and with the term
“dietary supplement,” which “may be modified with the
name of such ingredient.” Id. § 343(s)(2)(A)(i), (B). Thus,
Section 343(s)(2)(B) permits Walmart to label its dietary
supplement with the name of its active ingredient, and the
“common and usual” name of that ingredient may be
determined pursuant to federal testing requirements.
Hollins’s proposed rule to the contrary is preempted. See id.
§ 343-1(a)(3).
    Durnford does not hold otherwise. Contrary to Hollins’s
and the dissent’s argument, Durnford’s conclusion did not
rest on any distinction between federal requirements for
information in the nutrition panel or information elsewhere

8
  This argument is contrary to her argument before the district court,
where Hollins conceded that all of her claims, not just the claims
regarding the information provided in the nutrition panel, were subject
to federal testing requirements in accordance with 21 C.F.R. § 101.9.
20                 HOLLINS V. WALMART, INC.

on the label. In Durnford, a consumer brought state-law
claims against a manufacturer of a nutritional supplement for
false or misleading statements about protein contained in one
of its products. 907 F.3d at 597. The consumer claimed that
the protein in the supplement was augmented by nitrogen-
spiking agents, and argued that two types of claims on the
label were misleading: (1) the claim that the product
contained 40 grams of protein per serving, and (2) the claim
that the protein was from “hydrolyzed beef protein and
lactoferrin.” Id. at 598–99. These claims appeared on the
nutrition panel as well as in a description of the product’s “5-
stage mass delivery system” elsewhere on the label. Id. at
598. On appeal, we held that the district court correctly
dismissed the first claim based on the amount of protein. Id.
at 601–03. We reasoned that federal regulations, see 21
C.F.R. § 101.9(c)(7), permitted the manufacturer’s method
for determining the amount of protein, and because the
“regulations have the same preemptive effect as a statute,”
they “foreclose the possibility of liability under state law for
nitrogen spiking,” 907 F.3d at 602. In reaching this
conclusion, we did not distinguish between information on
the nutrition panel or information elsewhere on the label.
    We reversed the district court’s dismissal of the
consumer’s second claim, that the product’s label misled
him into believing that the protein came entirely from
hydrolyzed beef protein and lactoferrin, rather than partly
from nitrogen-spiking agents. Id. at 603–04. Because the
consumer’s argument did not go “to the amount of protein,
but to its composition,” there were no federal testing
requirements on point, and so the claim was not preempted.
Id. at 603.
    Nothing in Durnford suggests its analysis applied only
to the nutrition panel, and indeed, the same information
                      HOLLINS V. WALMART, INC.                         21

about the quantity and source of protein was available both
in the panel and elsewhere on the label. Id. at 598. 9
Therefore, our case is governed by Durnford’s holding that
the manufacturer’s method for determining the amount of
protein in the supplement was authorized by regulation and
therefore preempted the plaintiff’s proposed state-law rule.
Id. at 602 (citing 21 C.F.R. § 101.9(c)(7)). (We allowed the
claim regarding the source of protein to go forward only
because there were no federal testing requirements for
identifying protein composition.) Here, as in Durnford,
federal law permits Walmart to identify its product as
glucosamine sulfate potassium chloride, and Hollins’s
proposed state rule that a blend of glucosamine
hydrochloride and potassium sulfate cannot be labeled
glucosamine sulfate or glucosamine sulfate potassium
chloride is not identical to the federal rule. And as we held
in Durnford, such a rule is preempted as a matter of law. 21
U.S.C. § 343-1(a)(3), (4).
    In arguing against the conclusion that FDA regulations
preempt Hollins’s state-law mislabeling claims, the dissent

9
   The dissent’s claim that Durnford made a distinction between
“misrepresentations on the nutrition panel,” which were preempted, and
a “misrepresentation on the rest of the label,” which was not, Dissent 26,
takes the language in the opinion out of context. In fact, Durnford
considered only the distinction between the label’s information about the
amount of protein and the source of the protein. 907 F.3d at 602–04.
The opinion did not put any weight on the location of the information.
Thus, Durnford explained that “[u]nder Durnford’s theory of
misbranding, whether or not there was compliance with the FDA’s 12-
sample testing protocol does not matter,” because the testing protocol is
relevant only to “the proper means of calculating protein content in
dietary supplements,” and “Durnford’s protein composition theory [was]
not concerned with the total amount of protein in the Supplement; it
[was] concerned with the source of that protein.” Id. at 603–04.
22                     HOLLINS V. WALMART, INC.

raises a new argument not made by either party. According
to the dissent, Hawkins v. Kroger Co., 906 F.3d 763 (9th Cir.
2018) supports the argument that regulatory requirements
applicable to the nutrition panel are not applicable to
information elsewhere on the label. Dissent at 28. But
Hawkins is inapposite here.           Hawkins involved two
inconsistent FDA regulations governing a label’s claims
about the amount of trans fat in a product. One regulation
mandated that the nutrition panel follow certain “rounding
rules” with respect to nutrient levels, id. at 772, including the
rule that “[i]f the serving contains less than 0.5 gram [of trans
fat], the content shall be expressed as zero,” id. at 770
(quoting 21 C.F.R. § 101.9(c)(2)(ii)). A second regulation,
which governed “nutrient content claims” made outside the
nutrition panel, mandated that claims regarding nutrient
levels not be “false or misleading in any respect.” Id. at 770–
71 (quoting 21 C.F.R. 101.13(i)(3)).10 We resolved this
conflict by holding that a manufacturer was bound to follow
the rounding rules for the nutrition panel, but could not make
the same misleading claim elsewhere on the label. Id. at
771–72. In light of the federal regulation precluding
misleading nutrient content claims, we held that the FDA
regulations did not preempt a plaintiff’s state-law claim that
a statement on a product’s label (and not within the nutrition
panel) advertising zero grams trans fat was misleading. Id.
at 772.
   Hawkins is inapposite here. This case does not involve
a nutrient content claim, conflicting regulations, or any
regulation requiring a manufacturer to make a misleading

10
  A “nutrient content claim” is defined as “[a] claim that expressly or
implicitly characterizes the level of a nutrient” of a specific type, such as
calories, sodium, or fat. 21 C.F.R. § 101.13(b) (emphasis added).
                       HOLLINS V. WALMART, INC.                         23

claim. Rather, the regulations here detail an appropriate
testing method to determine the “common or usual name” of
an ingredient for purposes of the nutrition panel, 21 C.F.R.
§ 101.36(b)(3)(i), and raise the question whether using that
“common or usual name” of the active ingredient elsewhere
on the label constitutes offering the product for sale “under
the name of another food,” 21 U.S.C. § 343(b). Because,
unlike in Hawkins, federal testing regulations governing the
nutrition panel do not require the use of misleading
information, there is no conflicting federal regulation which
would prevent the use of the name determined in accordance
with the federal testing requirements elsewhere on the label.
Therefore, the federal rules preempt any state rules that
might preclude the use of the name of an ingredient
determined in accordance with federal testing
requirements.11
    Applying the summary judgment standard, there is “no
genuine dispute as to any material fact” that Hollins’s
mislabeling claims would “permit a state to impose
requirements” for labeling a dietary supplement such as
Walmart’s glucosamine sulfate potassium chloride product
“different from those permitted under the FDCA.”
Durnford, 907 F.3d at 603. Therefore, the claims are
preempted, see 21 U.S.C. § 343-1(a)(3), (4), and Walmart is
entitled to judgment as a matter of law.12

11
  The dissent’s reliance on Rigo Amavizca v. Nutra Mfg., LLC, No. 8:20-
cv-01324, 2021 WL 682113 (C.D. Cal. Jan. 27, 2021), is misplaced.
Dissent at 25–26, 28–30. We are not bound by this district court case,
and its reasoning is not persuasive for the reasons stated in this opinion.
12
   Prior to considering the second summary judgment motion, after
Hollins completed testing, the district court granted Walmart’s motion to
dismiss Hollins’s claims for equitable restitution, disgorgement, and
24                   HOLLINS V. WALMART, INC.

        AFFIRMED.

WARDLAW, J., dissenting in part:
    I write separately to clarify the applicability of the
Federal Drug Administration’s (FDA’s) testing and sampling
requirements to Hollins’s state-law mislabeling claims. In
my view, Hollins is not required to comply with the FDA’s
testing requirements with respect to her claims outside of the
nutrition facts panel. Challenges to the label under 21 U.S.C.
§ 343(b) are distinct from those to the nutrition facts panel
(the “nutrition panel”) under 21 U.S.C. § 343(q), such that
the 21 C.F.R. § 101.9(g) federal testing requirements do not
apply to the label outside of the nutrition panel, and,
therefore, these claims are not preempted by federal law.
                                  I.
    According to the National Institute of Health’s website,
glucosamine sulfate potassium chloride (what Hollins
believed she was purchasing) and glucosamine
hydrochloride with potassium sulfate (what Hollins actually
purchased) are chemically and molecularly different. See
Appendix A. “[N]ot all glucosamines are the same . . . .
[G]lucosamine sulfate has demonstrated clinical
effectiveness for certain [health] conditions, whereas other
forms of glucosamine have not. The common perception of
glucosamine sulfate is that it performs better than

unjust enrichment for failure to allege that she lacked a legal remedy,
under Sonner v. Premier Nutrition Corp., 971 F.3d 834, 844 (9th Cir.
2020). Because we find Hollins’s claims were preempted, we need not
reach the issue of whether the district court erred in dismissing these
claims. We also need not address Hollins’s arguments that the district
court erred by assessing Spingarn’s credibility on summary judgment.
                      HOLLINS V. WALMART, INC.                         25

glucosamine hydrochloride; consumers therefore prefer the
former, and companies charge more for it.” Rigo Amavizca
v. Nutra Mfg., LLC, No. 20-01324, 2021 WL 682113, at *1
(C.D. Cal. Jan. 27, 2021). 1 While Hollins is unable to prove
the distinction between the two molecules through a
validated testing and sampling method as required under 21
C.F.R. § 101.9(g)(2), such testing requirements apply only
to Hollins’s § 343(q) nutrition panel claims, not her § 343(b)
mislabeling claims. Accordingly, Hollins’s state law claims
regarding the label outside of the nutrition panel can
proceed.
                                   II.
                                   A.
    The majority opinion misapplies Durnford v.
MusclePharm Corp., 907 F.3d 595, 604 (9th Cir. 2018). The
majority interprets our decision in Durnford narrowly,
finding that it stands only for the proposition that challenges
to a label’s characterization of the source of an ingredient are
exempt from the Food, Drug, and Cosmetic Act (FDCA).
Maj. Op. 21. In fact, Durnford’s reasoning supports
Hollins’s position—at least in part—that some of her claims
are not preempted by federal law.

1
  See also Lucio C. Rovalti et al., Crystalline Glucosamine Sulfate in the
Management of Knee Osteoarthritis: Efficacy, Safety, and
Pharmacokinetic Properties, 4 Therapeutic Advances in Musculoskeletal
Disease 167, 167 (2012) (“As a whole, the use of glucosamine in the
management of osteoarthritis is supported by the clinical trials performed
with the original prescription product, that is, crystalline glucosamine
sulfate. This is the stabilized form of glucosamine sulfate, while other
formulations or different glucosamine salts (e.g. hydrochloride) have
never been shown to be effective.”).
26                HOLLINS V. WALMART, INC.

   In Durnford, a consumer brought claims against
MusclePharm Corporation, a manufacturer of nutritional
supplements, “for making false or misleading statements
about the protein in one of its products.” Id. at 597. We
concluded that some, but not all, of Durnford’s state-law
misbranding claims were preempted by federal law. Id.
    We made two distinctions between claims which were
preempted and those which were not. First, we noted that
the “FDCA and its implementing regulations concern only
the calculation and disclosure of protein amounts.” Id. But
“[t]hey say nothing about the source or composition of
protein,” and “Durnford’s claims are therefore not
preempted to the extent they arise under that theory.” Id.
    But we made a second distinction which the majority
ignores. We explained that Durnford’s mislabeling theory
which referred to misrepresentations on the nutrition panel
was preempted, but that his theory which referred to
misrepresentation on the rest of the label was not. See id. at
602–604. Specifically, we held that “[u]nder Durnford’s
theory of misbranding [related to the label outside of the
nutrition panel], whether or not there was compliance with
the FDA’s 12-sample testing protocol [did] not matter.” Id.
at 603.
   The second distinction is pertinent here. As the Durnford
Court aptly explained in a footnote:

       We refer to the product’s packaging as a
       whole as the “label.” We refer to the
       federally mandated declaration of nutritional
       content within the label as the “nutrition
       panel” . . . [T]he latter is subject to a unique
       set of stringent federal regulations.
                  HOLLINS V. WALMART, INC.                27

Id. at 598 n.1 (emphasis added).
    The majority focuses on only one of Durnford’s
distinctions—the amount versus the content of the protein in
the supplement. But Durnford’s second distinction—
between “[t]he label – separately from the mandatory
nutrition panel”—is controlling here such that the testing
requirements under 21 C.F.R. § 101.9(g)(2) do not apply to
Hollins’s § 343(b) misnaming claims beyond the nutrition
panel, and therefore these claims are not preempted. Id. at
603.
    Accordingly, even though Hollins cannot show that the
product she purchased is mislabeled on the nutrition panel
based on the 21 C.F.R. § 101.9(g)(2) testing requirements,
she can still state a mislabeling claim. Under § 343(b),
Hollins can show that the product was offered for sale under
the name of another food because the supplement’s
packaging names the product “glucosamine sulfate
potassium chloride,” and she has presented evidence that this
substance is structurally and chemically different than
glucosamine hydrochloride blended with potassium
sulfate—what the supplement actually contained. The fact
that Hollins cannot prove the distinction between the two
molecules through the federal sampling and testing
requirements is irrelevant to her § 343(b) claims.
    Further, even assuming there is no distinction between
glucosamine sulfate potassium chloride and glucosamine
hydrochloride with potassium sulfate, Hollins has an
additional mislabeling claim because when the suit was filed
the supplement’s front label stated the product’s name as
“glucosamine sulfate,” but the nutrition panel listed the
product as “glucosamine sulfate potassium chloride,” a
different supplement.
28                 HOLLINS V. WALMART, INC.

                              B.
    We also recognized the distinction between claims on the
nutrition panel and those “made elsewhere on the [label]” in
Hawkins v. Kroger Co., 906 F.3d 763, 770 (9th Cir. 2018).
In Hawkins, we were tasked with determining “whether [ ]
FDA trans fat regulations governing the content of the
Nutrition Facts Panel preempt” state mislabeling claims
“elsewhere on a food product’s label.” Id. at 767. We held
that the “rules[] contained in 21 C.F.R. § 101.9[] govern[]
what must be stated within the Nutrition Facts Panel,” and
“[c]ritically, the rules that govern claims made within the
Nutrition Facts Panel and the rules that govern nutrition
content claims elsewhere on the label are different.” Id. at
770.
    To be sure, the nutrition panel versus packaging label
distinction in Hawkins focused on nutrient content claims,
which are not at issue here. But our holding that “the FDA
regulations did not preempt a plaintiff’s state-law claim that
a statement on a product’s label (and not within the nutrition
panel) . . . was misleading,” Maj. Op. 22, highlights the
distinction between the nutrition panel and the rest of the
product’s label and further lends support to the conclusion
that only Hollins’s § 343(q) claims related to the nutrition
panel are subject to the federal testing and sampling
requirements.
                              C.
    The majority opinion is also inconsistent with a related
district court case, Amavizca. Amavizca dealt with nearly
identical facts to the case before us. There, plaintiffs brought
state law mislabeling claims against a supplement
manufacturer arguing that the supplement they purchased
was labeled as glucosamine sulfate, when in fact the
                   HOLLINS V. WALMART, INC.                29

substance was actually glucosamine hydrochloride and
sodium sulfate. 2021 WL 682113 at *2. The Amavizca
defendants argued, as Walmart does here, that the plaintiff
consumers’ claims were preempted. Id. at *4.
    Although not binding on us, Amavizca’s analysis is
persuasive. Relying on the FDA preemption framework we
laid out in Durnford, the Amavizca court concluded that the
consumer plaintiffs were not required to comply with the
federal testing requirements for their label-related claims,
but were required to comply if they sought to prove their
nutrition panel-related claims. Id. at *5. The Amavizca court
explained:

        Plaintiff's allegations thus implicate different
        provisions of the FDCA and FDA
        regulations. Plaintiff's allegation that the
        “Supplement Facts” panels on Defendants’
        products        contain      misrepresentations
        implicates 21 U.S.C. § 343(q) and 21 C.F.R.
        § 101.36, which govern the nutrition labeling
        of dietary supplements. Plaintiff’s allegation
        that Defendants’ Products have the words
        “Glucosamine           Sulfate”       displayed
        prominently on the label, however,
        implicates 21 U.S.C. § 343(b), under which a
        food is deemed misbranded “[i]f it is offered
        for sale under the name of another food.” 21
        U.S.C. § 343(b).

Id. at *4.
    Further, the Amavizca court emphasizes that the
requirements of 21 C.F.R. §§ 101.36 and 101.9(g) govern
“the nutrition labeling of dietary supplements,” and “FDA
30                 HOLLINS V. WALMART, INC.

regulations define ‘nutrition labeling’ as synonymous with
‘Supplement Facts’ panels.” Id. Accordingly, here, as in
Amavizca, Hollins’s claims that are not premised on the
“‘nutrition labeling’ or ‘Supplement Facts’ panels . . . do not
implicate the testing method set forth in 21 C.F.R.
§ 101.9(g)(2).” Id. at *5.
    The district court in Amavizca properly relied on our
decision in Durnford in holding that the distinction between
the overall label and the nutrition panel applies not only to
nutrient content claims, but also to other mislabeling claims.
By contrast, the majority opinion disregards our circuit
precedent by failing to follow the distinction required by
Durnford and applied in Amavizca.
                              III.
    Finally, the majority opinion runs counter to the
presumption against preemption. Hawkins, 90 F.3d at 769
(“[I]n all pre-emption cases, and particularly in those in
which Congress has ‘legislated . . . in a field which the States
have traditionally occupied,’ . . . we ‘start with the
assumption that the historic police powers of the States were
not to be superseded by the Federal Act unless that was the
clear and manifest purpose of Congress.’”) (alterations in
original) (quoting Wyeth v. Levine, 555 U.S. 555, 565
(2009)).
    Even assuming the majority is correct that this is an
express preemption case, only when “the statute’s language
is plain,” should the language of the preemption clause itself
end our inquiry. Puerto Rico v. Franklin Cal. Tax-Free Tr.,
579 U.S. 115, 125 (2016) (quoting United States v. Ron Pair
Enter., Inc., 489 U.S. 235, 241 (1989)). Here, contrary to the
majority’s assertion, the applicable FDCA preemption
provision is unclear.
                   HOLLINS V. WALMART, INC.                 31

    The FDCA limits preemption to “any requirement for
nutrition labeling of food that is not identical to the
requirements of section 343(q).” 21 U.S.C. § 343-1(a)(4)
(emphasis added).       Although the “any requirement”
language is broad, the “nutrition labeling” requirement
creates some ambiguity. As the Hawkins court points out,
“[s]omewhat confusingly, the FDA regulations refer to the
ubiquitous box that contains nutritional facts as ‘nutrition
labeling,’ 21 C.F.R. § 101.9, while also referring to the rest
of the product’s exterior as labeling.” Hawkins, 906 F.3d at
766 n.1. Accordingly, the plain language of the statute
supports the contention that the clause applies only to the
nutrition panel, or at a minimum, creates ambiguity as to
whether all labeling claims, or only those in the nutrition
panel, are subject to § 343(q)’s regulations for preemption
purposes.
    Because the statutory language is ambiguous, and we are
instructed to construe ambiguous federal statutes not to
preempt state law whenever possible, the presumption
against preemption applies here. See, e.g., Altria Grp., Inc
v. Good, 555 U.S. 70, 77 (2008) (“[W]hen the text of a pre-
emption clause is susceptible of more than one plausible
reading, courts ordinarily ‘accept the reading that disfavors
pre-emption.’”) (quoting Bates v. Dow Agrosciences LLC,
544 U.S. 431, 449 (2005)).
                             IV.
    In sum, I respectfully disagree with the majority’s
holding to the extent it finds that the federal testing and
sampling requirements apply to Hollins’s state-law
mislabeling claims targeting the label outside of the nutrition
panel. Accordingly, I would hold that such claims are not
preempted by the FDCA and allow them to proceed.
 32               HOLLINS V. WALMART, INC.

                      APPENDIX A
 Depictions of the different molecular structures of the
 molecules:
Glucosamine Sulfate                Glucosamine Hydrochloride
Potassium Chloride                 with Potassium Sulfate

 See PubChem Compound Summary for CID 76965765,
 Glucosamine Sulfate Potassium Chloride, Nat’l Ctr. for
 Biotechnology                                     Info.,
 https://pubchem.ncbi.nlm.nih.gov/compound/Glucosamine-
 sulfate-potassium-chloride (last visited Feb. 7, 2023);
 PubChem Compound Summary for CID 2723635,
                 HOLLINS V. WALMART, INC.             33

Glucosamine hydrochloride, Nat’l Ctr. for Biotechnology
Info.,
https://pubchem.ncbi.nlm.nih.gov/compound/Glucosamine-
hydrochloride (last visited Feb. 7, 2023); PubChem
Compound Summary for CID 24507, Potassium Sulfate,
Nat’l        Ctr.       for       Biotechnology   Info.,
https://pubchem.ncbi.nlm.nih.gov/compound/Potassium-
Sulfate (last visited Feb. 7, 2023).