Lee v. Amazon.com, Inc. ( 2022 )


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  • Filed 4/8/22 (unmodified opn. attached)
    CERTIFIED FOR PUBLICATION
    IN THE COURT OF APPEAL OF THE STATE OF CALIFORNIA
    FIRST APPELLATE DISTRICT
    DIVISION TWO
    LARRY LEE,
    Plaintiff and Appellant,                   A158275
    v.                                                (Alameda County
    AMAZON.COM, INC.,                                 Super. Ct. No. RG14738130)
    Defendant and Respondent.
    ORDER MODIFYING OPINION
    AND DENYING REHEARING
    [NO CHANGE IN JUDGMENT
    THE COURT:
    It is ordered that the opinion filed herein on March 11, 2022, be
    modified as follows:
    1. On page 4, second line of first full paragraph, delete the words
    “purchased from Amazon.”
    2. On page 4, at the end of the first full paragraph, add the following
    new final sentence:
    The Monsepa sample tested was purchased from
    aztopselstore.com and appears to be the same as the Monsepa
    product available from Amazon; the other four samples tested
    were from products purchased from Amazon.
    3. On page 11, first and second lines of last partial paragraph, delete
    the word “the” before “product page” and replace it with “Amazon’s,” delete
    the word “the” before “Monsepa,” and delete the words “Lee had tested.”
    These lines should read:
    1
    Steinberg was shown a customer comment on Amazon’s product
    page for Monsepa cream saying the news had reported on
    January 9, . . .
    4. On page 12, second line of second partial paragraph, after “health
    risks from,” delete the words “chemical exposures,” and replace with
    “exposure to chemicals including mercury,”
    5. On page 12, delete everything after the first sentence of footnote 15
    and replace it with the following:
    He had taught part of a course on risk assessment at San Diego
    State University School of Public Health for about 20 years,
    worked with governmental committees on developing and
    defining methods to assess health risks, and performed more
    than 200 Proposition 65 risk assessments, of which more than 50
    involved metals, more than 50 involved chemicals listed as
    reproductive or developmental toxicants, and “[a]lmost all” had a
    component of “generalizing data to the population of the products
    that we used.” Sheehan had experience evaluating mercury
    exposure in the contexts of site risk assessment, waste disposal,
    and a project involving removal of gas pressure regulators from
    homes.
    6. On page 18, delete footnote 16, and on page 28, delete footnote 19,
    which will require renumbering of all subsequent footnotes.
    7. On page 28, first line of first full paragraph, delete the word “five”
    and replace with “four.”
    8. On page 28, second line of first full paragraph, after the words “Web
    site” add the following: “, as well as a fifth such product that appears to be
    available for sale on the Web site,” The first two lines should read:
    Given the undisputed evidence that samples of four skin-
    lightening products purchased on Amazon’s Web site, as
    well as a fifth such product that appears to be available
    for sale on the Web site, contained high levels of mercury as . . .
    9. On page 80, second line of second full paragraph of “DISPOSITION”
    section, add the word “four” before “products.”
    2
    10. On page 80, at the end of the second full paragraph of the
    “DISPOSITION” section, add the following new final sentence:
    As to the fifth product tested for this case, the trial court shall
    determine whether the Monsepa product available on Amazon’s
    Web site was in fact the same product as the one tested.
    11. On page 80, after the second full paragraph of the “DISPOSITION”
    section, add the following new third paragraph:
    If any violations of Proposition 65 are established, the court shall
    determine the appropriate remedy in accordance with section
    25249.7.
    There is no change in the judgment. The petitions for rehearing are
    denied.
    Dated: __________________                         _________________________
    Richman, Acting P.J.
    3
    Trial Court:                                Alameda County Superior Court
    Trial Judge:                                Hon. Robert McGuiness
    Attorney for Plaintiff and Appellant        Law Office of Jonathan Weissglass
    Larry Lee:                                  Jonathan Weissglass
    Greenfire Law
    Rachel S. Doughty
    Jessica L. Blome
    Attorneys for Amicus Curiae on behalf       Rob Bonta
    of Plaintiff and Appellant:                 Attorney General of California
    Dennis A. Ragen
    Roxanne Carter
    Deputy Attorneys General
    Attorneys for Amicus Curiae                 Danielle R. Fugere
    As you Sow on behalf of Plaintiff           Chelsea J. Linsley
    Appellant:
    Attorneys for Amicus Curiae                 Altshuler Berzon
    Center For Food Safety on behalf            Barbara J. Chisholm
    of Plaintiff and Appellant:                 P. Casey Pitts
    Attorneys for Amici Curiae Black            Environmental Law Clinic
    Women for Wellness and the Mercury          Mills Legal Clinic at Stanford Law School
    Policy Project/Tides Center on behalf       Deborah A. Sivas
    of Plaintiff and Appellant:                 Molly Loughney Melius
    Attorneys for Defendant                     Doll Amir & Eley
    and Respondent Amazon.com, Inc.:            Gregory L. Doll
    Brett H. Oberst
    Jamie O. Kendall
    Lloyd Vu
    Attorneys for Amicus Curiae                 Law Office of Fred. J. Hiestand
    The Civil Justice Association of            Fred J. Hiestand
    California on behalf of Defendant
    and Respondent:
    4
    Filed 3/11/22 (unmodified opinion)
    CERTIFIED FOR PUBLICATION
    IN THE COURT OF APPEAL OF THE STATE OF CALIFORNIA
    FIRST APPELLATE DISTRICT
    DIVISION TWO
    LARRY LEE,
    Plaintiff and Appellant,
    A158275
    v.
    AMAZON.COM, INC.,                            (Alameda County
    Super. Ct. No. RG14738130)
    Defendant and Respondent.
    Under legislation enacted as Proposition 65 in 1986, businesses are
    prohibited from knowingly and intentionally exposing any individual to
    certain chemicals without first providing a warning. Lee seeks to hold
    Amazon.com, Inc. (Amazon) accountable for offering on its Web site, without
    warnings, certain skin-lightening face creams sold by third parties and
    alleged to contain mercury. The trial court concluded that Amazon is
    immune from liability under the federal Communications Decency Act (CDA)
    and also that Lee failed to establish several elements of his case under
    Proposition 65.
    Lee maintains Amazon is not protected by the CDA and the trial court
    erred in its view of the evidence required to establish the alleged statutory
    violations.
    1
    We agree with Lee and, therefore, will reverse and remand for further
    proceedings. 1
    BACKGROUND
    California’s Safe Drinking Water and Toxic Enforcement Act of 1986
    (Act) (Health & Saf. Code, § 25249.5 et seq.), adopted by voter initiative in
    1986 and commonly known as Proposition 65, provides, “No person in the
    course of doing business shall knowingly and intentionally expose any
    individual to a chemical known to the state to cause cancer or reproductive
    toxicity without first giving clear and reasonable warning to such individual,
    except as provided in Section 25249.10.” (Health & Saf. Code, § 25249.6.)
    Mercury and mercury compounds were listed by the state as reproductive
    toxins under Proposition 65 in 1990. (Cal. Code. Regs., tit. 27, 2 § 27001,
    subd. (c); see Health & Saf. Code, § 25249.8.) 3
    1 The Attorney General filed an amicus brief in support of Lee pursuant
    California Rules of Court, rule 8.200(c)(7). Exercising his authority to
    represent the public interest, the Attorney General explains he has a “special
    interest in the proper interpretation and enforcement of” Proposition 65 as
    the “public official with statewide authority to enforce” the Safe Drinking
    Water and Toxic Enforcement Act of 1986 and “the only public official with
    authority to review and comment on settlements entered into by private
    enforcers under Proposition 65.”
    Additionally, we granted applications to file amicus briefs from several
    nonprofit organizations whose missions relate to the subject matter of this
    case. We have received amicus briefs on behalf of Lee from As You Sow and
    Center for Food Safety, Black Women for Wellness and the Mercury Policy
    Project/Tides Center, and on behalf of Amazon from the Civil Justice
    Association of California.
    2Further references to “Regulations” are to title 27 of the California
    Code of Regulations except as otherwise specified (e.g., Regs., § 25102).
    3Under California law, a discarded substance is “hazardous waste” if it
    contains 20 milligrams per kilogram, 20 parts per million (ppm) or more of
    2
    Cosmetics containing one ppm (0.0001 percent) or more of mercury are
    prohibited under federal law. (
    21 U.S.C. § 331
    (a)–(c); 
    21 C.F.R. § 700.13
    (d)(2)(i).) 4 According to the FDA, “[t]he toxicity of mercury
    compounds is extensively documented in scientific literature. . . . Mercury is
    absorbed from topical application and is accumulated in the body, giving rise
    to numerous adverse effects. . . . [C]hronic use of mercury-containing skin-
    bleaching preparations has resulted in the accumulation of mercury in the
    body and the occurrence of severe reactions.” (
    21 C.F.R. § 700.13
    (b).)
    The present case concerns four brands of face creams advertised as
    skin-lightening or skin-whitening products: Faiza, Face Fresh, Monsepa, and
    Meiyong.
    Lee’s second amended complaint listed 27 products offered for sale on
    Amazon’s Web site under these brand names, identified by individual product
    name or description and “Amazon Standard Identification Number” or
    mercury. (Cal. Code Regs., tit. 22 §§ 66261.2, subd. (a), 66261.20, subd. (a),
    66261.24, subd. (a)(2)(A).)
    4  Federal law prohibits “[t]he introduction or delivery for introduction
    into interstate commerce of any . . . cosmetic that is adulterated or
    misbranded,” the “adulteration or misbranding of any . . . cosmetic in
    interstate commerce” and the “receipt in interstate commerce of any . . .
    cosmetic that is adulterated or misbranded, and the delivery or proffered
    delivery thereof for pay or otherwise.” (
    21 U.S.C. § 331
    (a)-(c).) The Food and
    Drug Administration (FDA) regards “any cosmetic containing mercury” as
    “adulterated” unless it contains “no more than a trace amount of mercury and
    such trace amount is unavoidable under conditions of good manufacturing
    practice and is less than 1 ppm (0.0001 percent), calculated as the metal”
    (21 C.F.R § 700.13(d)(2)(i)) or it is “intended for use only in the area of the
    eye, it contains no more than 65 ppm (0.0065 percent) of mercury, calculated
    as the metal, as a preservative, and there is no effective and safe
    nonmercurial substitute preservative available for use in such cosmetic.”
    (
    21 C.F.R. § 700.13
    (d)(2)(ii).)
    3
    “ASIN.” 5 His pretrial brief subsequently reduced the list of products at issue
    to 11, identified by ASIN and name or description: Three by Faiza, one by
    Face Fresh, one by Monsepa, and six by Meiyong. 6
    Lee had laboratory tests performed on samples of these products
    purchased from Amazon, which found 15,000 ppm mercury in a sample of
    Monsepa Express Peeling cream (ASIN B0030K8GJY) tested in 2017, 9,600
    ppm of mercury in a sample of Faiza Beauty cream (ASIN B00WORM8R0)
    tested in 2016, 5,600 ppm of mercury, in a sample of Face Fresh Beauty
    cream (ASIN B00ZP38YQY) tested in 2015, 21,000 ppm of mercury in a
    sample of Meiyong Seaweed Super Whitening cream (ASIN B00CVJKBDE)
    tested in January 2015, and 2,000 ppm of mercury in another sample of
    Meiyong Seaweed Super Whitening cream (ASIN B008XRYQUM) tested in
    September 2015.
    Several samples of Monsepa creams (not purchased from Amazon) had
    previously been tested for California agencies: Tests performed for the
    5The ASIN is an internal code assigned by Amazon to each unique
    product listed on the Web site.
    6The 11 products were: “Original Faiza Beauty Cream Whitening
    Cream Anti Pimple Cream Freckle Cream” (ASIN B00WORM8R0), “Faiza
    Beauty Cream/To Remove Freckles & Dark Spots” (ASIN B00V0LHLTM),
    “Faiza Beauty Cream – 30 gram – Whitening Cream ‐ Anti Pimple Cream –
    Freckle Cream” (ASIN B00XUY6FL6), “Face Fresh Beauty Cream” (ASIN
    B00ZP38YQY), “Monsepa Express Peeling Remove Dark Sports Face Cream”
    (ASIN B0030K8GJY), “Meiyong Super Extra Whitening Cream Seaweed Face
    Lift Natural Algae” (ASIN B00CVJKBDE), “Seaweed Cream – Extra
    Whitening & Face Lift” (ASIN B008XRYQUM), “Meiyong Seaweed Extra
    Whitening Formula & Face Lift Cream” (ASIN B00AS71WWU); “Seaweed
    Cream – Extra Whitening & Facelift” (ASIN B00UPXPMYQ), “Meiyong
    Brand Super Extra Whitening Cream Seaweed Face lift” (ASIN
    B00VCN3Z7Y), and “Meiyong Super White Cream Extra Whitening & Face
    Life Advanced Super Revitalizer” (ASIN B00HZFSBYU).
    4
    California Department of Public Health (CDPH) found 8,900 ppm mercury in
    a sample of Monsepa Express Peeling cream tested in May 2013, 13,000 ppm
    mercury in a sample of Monsepa Express Peeling cream tested in December
    2013, and a 2013 test for the California Department of Justice found 12,000
    ppm mercury in a sample of Monsepa Express Peeling cream and 20,000 ppm
    mercury in a sample of Monsepa Whitening Peel.
    Additionally, in 2013, the European Union’s Rapid Alert System for
    dangerous non-food products (RAPEX) issued two alerts for Faiza Beauty
    Cream, one reporting 5,430 ppm mercury and the other reporting 5,940 ppm
    mercury, and an alert for Face Fresh Beauty Cream reporting 4,620 ppm
    mercury.
    The CDPH issued a health risk warning on January 14, 2014, for
    certain imported skin-lightening creams that had been found to contain high
    levels of mercury, including “Monsepa Bleaching Express Peeling.”
    Lee provided Amazon a 60-day “Notice of Violation” pursuant to
    Proposition 65 (Health & Saf. Code, § 25249.7, subd. (d)) dated May 22, 2014.
    He filed his complaint for civil penalties and injunctive relief on August 25,
    2014.
    After a bench trial in January 2019, the trial court ruled in favor of
    Amazon, finding the company immune from liability under section 230 of the
    federal CDA (
    47 U.S.C. § 230
    ). 7 The court also found that while Amazon
    could have a duty to warn under Proposition 65 for third-party sales of the
    products at issue, Lee failed to prove each element of his claim under
    Proposition 65—specifically, that Lee did not prove each of the products at
    issue contained mercury, that test results finding mercury in a unit of the
    products at issue should be generalized to other units of that product or
    7   Further references to “section 230” are to title 47 United States Code.
    5
    similar products, that the creams sold on Amazon’s Web site were actually
    used by consumers, and that Amazon had actual knowledge the products
    contained mercury at the time they were purchased without a Proposition 65
    warning.
    Mercury in Skin-Lightening Creams
    As described by Lee’s expert witness on mercury in skin-whitening
    creams and resultant health risks, Dr. Gina Solomon, 8 mercury exists in
    three forms (elemental, inorganic and organic), all of which are toxic, with
    serious effects on bodily systems and organs at a cellular level. Inorganic
    mercury (the form used in skin creams) is “very, very toxic” to kidney
    function and also has serious effects on reproductive function and fetal
    development. Animal studies consistently show reduced fertility, fetal
    viability and birth weights at “pretty low level exposures.” In both humans
    and rodents, prenatal exposure at “pretty low levels” has been shown to
    result in profound deafness. Solomon testified that the levels of mercury
    found in skin creams are in the same range as those shown to cause these
    8 Dr. Solomon was a principal investigator at the Public Health
    Institute and clinical professor in the Division of Occupational
    Environmental Medicine at the University of California San Francisco. Her
    background included serving as the deputy secretary for the California
    Environmental Protection Agency, where her work included developing
    sampling plans for hazardous material cleanup, including work with metals
    such as lead, mercury and arsenic, and extensive work with OEHHA on
    Proposition 65 issues; teaching medical students, residents and fellows, and
    supervising them on clinical work regarding complex toxicology issues;
    teaching continuing medical education classes for doctors and developing the
    original curriculum for a CDPH program for physicians on the human health
    effects of mercury; and treating patients exposed to dangerous levels of
    mercury from a skin cream product and collaborating with researchers
    investigating the case, which led to the CDPH’s health alert on mercury in
    skin-lightening creams, as well as work on the issue with other states’ health
    departments.
    6
    adverse effects in rodents, which tend to be less sensitive than humans to
    many neurologic and reproductive effects.
    The adverse effects of mercury are not limited to the direct users of the
    creams. The form of mercury used in skin-lightening creams—inorganic
    mercury—can release mercury vapor, especially in warm conditions. 9 The
    CDPH has found mercury contamination resulting from use of skin creams
    requiring extensive decontamination of houses, including items such as
    washing machines, mattresses and sofas, and disposal of items like toys,
    towels, and bedding as hazardous waste. In the case of a family Solomon
    treated for mercury poisoning, mercury vapor was found emanating from the
    hands of the woman who used the cream, and decontamination of her hands
    took a month of repeated applications of a binding compound.
    The primary users of skin-lightening creams are women, principally
    women of color. At the time of trial, the CDPH was conducting educational
    events in communities where the creams are known to be used, as well as a
    buyback program for people to return the creams and receive money to
    purchase substitutes.
    Not all skin-lightening creams contain mercury: CDPH tests of more
    than 100 skin-lightening creams found seven that were positive for
    mercury. 10 Of a total of five ingredients known to whiten skin, the only one
    permitted in the United States is hydroquinone.
    9 Solomon explained that mercury exists in three different forms
    (elemental, inorganic and organic), which have different properties, but can
    “inter-covert” in different settings.
    10None of the products tested in this study came from Amazon. The
    CDPH witness who testified at trial explained that they were collected from
    markets in targeted communities and online stores serving immigrant
    populations identified in the literature, or through poisoning investigations,
    as using these creams.
    7
    Solomon testified that public health issues with skin-whitening creams
    involve creams imported from certain countries in Asia, Mexico, and in a few
    cases Africa; Lee’s expert witness on cosmetic chemistry and Proposition 65
    warnings, David Steinberg, 11 testified that in his experience most skin-
    bleaching products containing mercury were made in Pakistan. Both
    testified that the claims made on listings on Amazon for the products Lee had
    tested—referring to removing dark spots, whitening skin and treating
    acne 12—were “red flags” indicating the product was for skin bleaching and
    11 Steinberg was the president of a consulting company that deals with
    “regulations and chemistry of cosmetics and topical pharmaceutical
    products.” His 50 years’ experience in the cosmetic industry included
    working on product development involving the chemistry of cosmetics,
    advising cosmetics companies on product and regulatory issues, teaching and
    publishing on the chemistry of cosmetics, and lecturing on quality assurance
    for cosmetics; he had experience with mercury in cosmetics and specifically in
    skin-lightening products, and with issues under Proposition 65.
    12 On the Amazon Web site, a listing for “Faiza Beauty Cream” (ASIN
    B00V0LHLTM) claims to “remove freckles & dark spots”; another—with the
    same product image, but a different ASIN (B00WORM8R0) and different
    Universal Product Code claims to be “the only cream that cleans pimples,
    wrinkles, marks, hives even dark circles under the eyes and turns your skin
    white.” The product listing for “Meiyong Super Extra Whitening Cream
    Seaweed Face life natural Algae” (ASIN B00CVJKBDE) includes “Help
    relieve acne, freckles and dark spots on the performance give a white skin.”
    Monsepa Express Peeling Remove Dark Spots Face Cream (ASIN
    B0030K8GJY) claims it “eventually removes even the deepest types of
    freckles, dark spots, butterfly spatches and yellow spots from your face” and
    “is specially effective to eradicate and even out acne scars.” Face Fresh
    Beauty Cream’s (ASIN B00ZP38YQY) claims include, “Best whitening
    cream,” “Anti Wrinkles,” “lightening dark spots,” and “Turns Your Skin
    White.”
    8
    might contain mercury. 13 This was particularly the case where a product
    claimed to both whiten skin and treat acne, because mercury is the only
    ingredient known to do both.
    Solomon testified that the mercury concentrations found in the creams
    tested in this case meant mercury was “definitely not” a “trace amount,” but
    rather an intentionally added active ingredient; the concentrations were
    “absolutely inconsistent” with mercury being a trace contaminant. The range
    of concentrations in the tested samples, between 2,000 and 21,000 milligrams
    per kilogram (2,000 to 21,000 ppm or .2 to 2 percent), was consistent with
    active ingredients in other consumer products, such as 2 percent of the
    herbicide in RoundUp, 1 percent cortisone in anti-inflammatory skin cream
    or .2 percent sodium fluoride in toothpaste. Prior to her work on this case,
    Solomon had seen the 2014 CDPH press release warning consumers about
    mercury in certain skin-lightening creams, including Monsepa, and believed
    the product contained mercury because she considered product warnings
    from the CDPH highly credible; the test results Lee obtained in 2017
    confirmed her opinion and showed the formula had not been changed despite
    the health alert.
    Based on the test results and language used in the Amazon listings for
    the skin whitening creams, Solomon was certain all units of the products
    tested would contain mercury. Solomon testified that “very little actual
    testing” is necessary to answer the “yes or no” question whether an
    intentionally added ingredient is present in a product, and regulatory
    agencies “not infrequently” base a decision on a single sample or very few
    13Amazon stipulated that all 27 products identified in the second
    amended complaint purported to be skin-lightening or skin-bleaching
    products.
    9
    samples. Factors such as how a product was stored and whether multiple
    manufacturers were used, could be relevant to a contamination issue, but
    would be irrelevant in determining whether an intentional ingredient was
    present because manufacturers are reluctant to change their formulas: They
    want consistency in the appearance, smell, and effect of consumer products,
    as consumers notice differences and do not like them. Solomon was careful to
    clarify that extrapolation from test results on one unit to other units of the
    same product was appropriate for “yes/no test results” for presence of
    mercury, not the exact concentrations detected.
    Steinberg similarly testified that the test results in evidence were
    sufficient to conclude the products at issue contained mercury because there
    was no way the amount of mercury found in samples Lee had tested could be
    due to a trace contaminant that might vary between batches or lots; it had to
    be a deliberately added ingredient He testified that in making emulsions
    (the form of the skin creams at issue), at least three or four tests are usually
    run per batch for purposes of quality control and quality assurance, to ensure
    uniformity and confirm the product meets specifications and is free of
    contamination, and most companies test each batch before filling individual
    containers for consumer sales. Testing of multiple batches of each product is
    not necessary to determine whether mercury is an ingredient in a cosmetic
    product, however, because at levels seen in this case, it has to have been
    deliberately added. The high levels of mercury found in the five samples Lee
    had tested, together with the products’ claims of skin whitening as the
    intended use, made Steinberg “very, very certain” other batches or lots of the
    same product would all contain mercury as an ingredient.”
    Steinberg acknowledged the possibility there could be variations in the
    chemical makeup of the products between batches; that he did not have
    10
    information about the companies’ specific manufacturing and packaging
    practices or know details such as when they began using mercury in their
    skin-bleaching products or whether they had another version of the product
    that used a different ingredient in place of mercury; and that some companies
    use different formulas in different countries for products branded and sold as
    the same product. He testified that if a company does not follow “current
    good manufacturing procedures” (cGMPs), which include matters such as
    manufacturing and testing methods and meeting product specifications, “all
    bets are off in terms of product consistency across units and batches and
    lots,” and many variables could make a difference in this regard. Steinberg
    did not know whether the companies here followed cGMPs, but he had reason
    to believe the products were sourced in Pakistan and no reason to expect
    companies in Pakistan to follow cGMPs.
    Nevertheless, Steinberg testified he could be “very certain” the
    products tested here contained mercury without analyzing every package
    because “cosmetic-like products” are manufactured in “larger amounts” with
    “a consistent formulation,” mercury is the active ingredient, and cosmetic
    companies do not like to change formulations of creams “unless it’s absolutely
    mandatory, or marketing just absolutely demands it, because it’s very time-
    consuming” and a significant added expense. A different chemical could not
    simply be substituted for mercury; the product would have to be “totally
    reformulate[d]” because the emulsion would not be stable.
    Steinberg was shown a customer comment on the product page for the
    Monsepa cream Lee had tested saying the news had reported on January 9,
    2014, that the product contained high levels of mercury, providing a link to
    the official alert on the CDPH Web site, and asking vendors to stop selling
    11
    it. 14 Steinberg testified he would advise a company that received a comment
    like this to immediately find out if there was mercury in the product. He
    further testified that as part of good business practices, it is important for a
    company offering cosmetics for sale on the Internet to monitor public health
    alerts and announcements by governmental agencies. His advice to a client
    that received the May 22, 2014, notice of violation Lee sent to Amazon would
    be to confirm whether the product it was manufacturing or selling contained
    mercury and, if so, recall the product and notify the FDA. Once Amazon was
    alerted to the presence of mercury in the creams, it should have immediately
    notified every purchaser of the product to discontinue use and halted sales of
    the product.
    Dr. Patrick Sheehan, Amazon’s expert witness on risk assessment and
    evaluation of health risks from chemical exposures, 15 agreed that mercury is
    a known ingredient in skin-lightening creams and that in each of the tested
    samples in this case, mercury was an ingredient, not a contaminate. He
    14 The comment expressed skepticism that the product was made in
    France (as was also stated on the bottle and packaging of the sample Lee had
    tested) because “the EU has strict cosmetic regulations.” Steinberg had
    “serious doubt” the product was made in France based on his experience
    dealing with officials in France, who would not have permitted it, and his
    knowledge that “these types of products using these types of ingredients . . .
    have been restricted almost exclusively to Pakistan.”
    15 Dr. Sheehan had worked in the field of risk assessment for 40 years,
    the last 19 of which he had been a consultant with a company called
    Exponent, advising clients on historic, current, and potential exposures and
    associated risks. He had taught part of a course on risk assessment at San
    Diego State University School of Public Health for about 20 years, worked
    with governmental committees on developing and defining methods to assess
    health risks, done more than 200 Proposition 65 risk assessments, and had
    experience evaluating mercury exposure in the contexts of site risk
    assessment, waste disposal, and a project involving removal of gas pressure
    regulators from homes.
    12
    testified, however, that these results could not be generalized beyond the
    units tested. Sheehan testified that test results from a single unit cannot be
    extrapolated even to other units in a batch because it is necessary to account
    for variability between units resulting from uneven distribution of chemicals
    within a batch, or between batches for products. Factors influencing
    variability include changes in ingredients or sources of the ingredients,
    changes or inconsistency in manufacturing processes and changes in the
    recipe for the product. Sheehan testified that the standard practice is to
    sample individual units within a batch to “understand the conditions of the
    individuals that make up that batch,” then “do the same thing in all of the
    batches that are of interest within the time frame of the evaluation so that
    you can say with confidence what is a condition of the population that is
    made up of all of those batches of individuals within those batches.”
    According to Sheehan, the literature on skin-lightening creams reflects
    variability as to measurable added mercury, with some batches having no
    detectable mercury and others having levels “related to added mercury.”
    Asked about the CDPH investigation in which seven of 120 samples of skin-
    lightening creams tested positive for significant amounts of mercury,
    Sheehan testified the data suggested there would be detectable added levels
    of mercury in relatively few skin creams. He disagreed with Steinberg and
    Solomon because they only evaluated the individual units tested, with no
    effort to “assess variability among batches or among products.” Asked if they
    followed “appropriate scientific method,” Sheehan testified, “I don’t believe
    they followed any method. They made some assumptions. So no, they did
    not follow any sort of standard method for characterizing variability within a
    product.”
    13
    Sheehan stated that Steinberg’s “assumption” that “under good
    manufacturing practice one would expect to find mercury in different batches,
    if you found it in one batch” was not supported by the data and literature,
    which contain “examples where there was mercury detected at some batches
    of a lot and not in others.” In Sheehan’s view, it did not make any difference
    that mercury was an added ingredient in the skin-lightening creams for the
    same reason: The literature indicated that “any measurement in one
    batch . . . will not tell you what is happening within the population of that
    skin-lightening cream.”
    Sheehan acknowledged that a study he conducted on whether users of
    talcum powder in the 1960’s and 1970’s were exposed to asbestos was based
    on analysis of five individual containers, each a different product. He also
    acknowledged that at his deposition he did not recall having worked on a
    cream applied to the body other than sunscreen, which he declined to answer
    questions about, and that he had never previously been an expert in a case
    involving mercury and skin-lightening cream, advised a client regarding
    mercury in skin-lightening creams, done any work evaluating the presence or
    absence of mercury in cosmetics, or otherwise had experience with analyzing
    heavy metal exposure in creams.
    Amazon’s Marketplace
    As described by Christopher Poad, Director of Amazon Business
    International, Amazon both sells products directly to customers through its
    “Amazon Retail” business and operates a “marketplace” through which third-
    party sellers sell products to customers. Approximately 2.5 million third
    parties list and sell approximately 600 million unique products on the
    Amazon Web site. In 2018, the total value of products sold on the Amazon
    14
    Web site worldwide was approximately $300 to $350 billion, 50 to 55 percent
    of which ($150 to $175 billion) were sales by third parties.
    Amazon provides third-party sellers with the ability to list their
    product for sale, provide a title, description and image for the listing, and
    have Amazon collect payment on the sellers’ behalf. Sellers can choose to
    fulfill orders themselves, making their own arrangements for warehousing
    and shipping, or use Amazon’s “Fulfillment by Amazon” or “FBA” service.
    With FBA, the third-party seller’s products are stored in an Amazon
    fulfillment center (warehouse), then shipped to the customer by Amazon
    when the seller makes a sale. For third-party sales, ownership of the product
    is transferred from the seller to the customer without Amazon taking title.
    By contrast, for Amazon Retail, Amazon purchases the merchandise from a
    supplier, owns it, and then resells it to the customer.
    The products at issue in this case were all placed on the Amazon Web
    site by third-party sellers, and at least one used the FBA service.
    Third-party sellers are required to consent to Amazon’s “Business
    Solutions Agreement,” which details matters including indemnification and
    insurance requirements for sellers. Amazon charges fees to sell products on
    the marketplace, which it earns when the seller completes a sale and the
    product is shipped to the customer. Customers use the Amazon Web site to
    complete purchases and in most transactions, there is no communication
    between customers and third-party sellers; if there is, it goes through the
    Amazon platform. Amazon’s Web site does not provide contact information
    for third-party sellers; it offers a “contact seller” option through which a
    customer can send a message, which Amazon forwards to the seller, and the
    seller can respond.
    15
    Each unique product on the Amazon Web site has its own product
    description page. The content for this page, including product name,
    description, price, and quantity available for sale, is provided by the third-
    party seller. When a third party creates a new product listing, if the product
    does not already exist on the Web site, it is assigned a new ASIN. Materials
    for sellers “encourage and require” them not to create duplicate listings and it
    is not in their interest to do so, because if there are two pages for a single
    product, each will only get half as many people looking at it. Amazon has
    software that scans the product catalog for products that look identical, or
    “very, very similar,” and merges such products onto a single page, and the
    customer service team is able to merge pages together if someone reports
    duplicates. According to Poad, it is not sufficient to look at product images to
    determine whether two are the same because manufacturers may change the
    contents without changing packaging and many use stock images for multiple
    products; instead, one must look at unique identifiers such as the Uniform
    Product Code, descriptions and titles.
    During the process for setting up the product description page, sellers
    “have the ability to flag whether the product they are selling requires a
    Proposition 65 warning for California residents,” and if they select this
    option, a warning is displayed on the product description page that links to a
    page in the customer help section of the Web site. In its “policies and
    agreements” for sellers, Amazon provides a list of examples of “prohibited
    listings” that includes “Products and ingredients that the [FDA] has
    determined present an unreasonable risk of injury or illness, or are otherwise
    unsafe, such as . . . [s]kin creams containing mercury.”
    Amazon’s director of worldwide product compliance and safety, David
    Kosnoff, testified in his deposition that the Amazon product safety team in
    16
    Europe reviews products listed on RAPEX notifications and these products
    are removed from Amazon’s European Web sites, but not necessarily those in
    other countries. If a product was listed on RAPEX in 2015, Amazon would
    have searched its European Web sites and, if the product was listed, would
    have taken down the listing and notified customers; the United States
    marketplace would not have been impacted. A recall in one country would
    not necessarily trigger recall in another because it can be difficult to
    determine whether products that appear identical in different countries are
    actually the same product.
    Kosnoff testified Amazon would have been aware of the 2013 RAPEX
    notification for Faiza Beauty Cream. He did not know whether the product
    was listed on Amazon’s European Web sites. He was aware a “very similar”
    product was listed on the United States Web site and did not believe any
    action would have been taken to notify the United States marketplace of the
    European recall. The record documents sales of Faiza Beauty Cream on the
    Amazon Web site through late 2015.
    Face Fresh, which was also the subject of a 2013 RAPEX notification,
    was being sold on Amazon’s Web site as of January 16, 2019.
    After Lee’s May 22, 2014, 60-day notice of violation, which listed
    Monsepa Express Peeling Night Face Cream as an example of “[s]kin-
    lightening creams,” on June 11, 2014, Amazon added a Proposition 65
    warning to the listing for Monsepa Express Peeling cream (ASIN
    B0030K8GJY). Between these dates, there were five sales of this product
    (May 23, 29, 31, June 2, 6). Amazon removed the listing from the Web site on
    August 12, 2014.
    17
    DISCUSSION
    We begin with the elements of the Proposition 65 claim because, as will
    be seen, the nature of this claim is critical to the question of immunity under
    section 230 of the CDA.
    I.
    The trial court found Lee did not prove that each of the 27 products
    identified in the second amended complaint contained mercury because Lee
    purchased and tested only one unit each of five products. 16 The court
    concluded the product detail pages from Amazon’s Web site that Lee
    introduced into evidence did not establish the 27 products originally
    identified were the same products he tested because the pages were for only a
    few products and contained “multiple material differences, including different
    “product names, pictures, sellers, descriptions, ASINs and UPCs.” The court
    therefore limited Lee’s claims to “the four products he purchased on Amazon
    and tested.”
    Moreover, the court found Lee did not prove the test results showing
    mercury in one unit of a given product should be generalized to other units of
    that product or similarly named ones because Lee did not introduce evidence
    of “how, when, where or by whom any of the tested units were manufactured,
    filled, stored, or distributed, including any lot or batch information for the
    tested samples,” leaving no scientific or evidentiary basis for determining
    whether other units of the same product or similar ones under the same
    16 The trial court referred to Lee having tested four products purchased
    from Amazon’s Web site, plus one unit of a fifth product purchased on
    www.aztopsel.com. As we understand the record, the five samples Lee had
    tested for this case were each from a product with a distinct ASIN, purchased
    on Amazon’s Web site, although the two Meiyong products had the same
    product name and the Monsepa product was shipped from aztopsel.com.
    18
    brand name contained mercury. The court pointed to a comment on the
    laboratory report for one of the samples Lee had tested, which stated, “Please
    note that these results apply only to the sample(s) submitted for this report.
    Samples from a different portion of the same lot may produce different
    results.” The court also observed that the RAPEX notices identified batch
    numbers for the product involved. The court rejected the opinions of Lee’s
    expert witnesses that the test results Lee obtained could be generalized to
    untested units, finding them contradicted by the testimony of Amazon’s
    expert witness and two of Lee’s own witnesses.
    Lee argues the trial court’s conclusions are both legally and factually
    unsupported. Preliminarily, he points out that the trial court ignored his
    narrowing of the products at issue from the 27 identified by ASIN in the
    second amended complaint to four products appearing under 11 ASINs on
    Amazon’s Web site, and argues the trial court erred in limiting the case to
    four ASINs for which laboratory tests were obtained. More fundamentally,
    he argues the trial court erred in concluding test results for one unit of a
    given product could not be extrapolated to other units of the same product for
    purposes of determining whether Proposition 65 warnings were required.
    Amazon treats these issues as purely factual, to be reviewed under the
    substantial evidence test. Focusing on descriptions of this test as requiring
    us to “look only to the evidence supporting the prevailing party” and “discard
    evidence unfavorable to the prevailing party” (Felgenhauer v. Soni (2004)
    
    121 Cal.App.4th 445
    , 449), Amazon argues the court’s conclusions were
    supported by its witnesses’ testimony—Poad’s, as to each ASIN representing
    a distinct product, and Sheehan’s (along with Steinberg’s and Dr. Brian
    Lee’s) as to a test of one unit being insufficient to demonstrate the presence of
    mercury in another unit of the same product.
    19
    To the extent these issues are purely factual, Amazon is of course
    correct that we review the trial court’s decision under the substantial
    evidence test. “ ‘In determining whether a judgment is supported by
    substantial evidence, we may not confine our consideration to isolated bits of
    evidence, but must view the whole record in a light most favorable to the
    judgment, resolving all evidentiary conflicts and drawing all reasonable
    inferences in favor of the decision of the trial court. (People v. Johnson (1980)
    
    26 Cal.3d 557
    , 576–578.) We may not substitute our view of the correct
    findings for those of the trial court; rather, we must accept any reasonable
    interpretation of the evidence which supports the trial court’s decision.’ ”
    (DiMartino v. City of Orinda (2000) 
    80 Cal.App.4th 329
    , 336, quoting Beck
    Development Co. v. Southern Pacific Transportation Co. (1996) 
    44 Cal.App.4th 1160
    , 1203–1204.) Nevertheless, we do not defer to the trial
    court’s decision entirely. (DiMartino, at p. 336.) “Substantial evidence is a
    deferential standard, but it is not toothless.” (In re I.C. (2018) 
    4 Cal.5th 869
    ,
    892.) “ ‘ “We may not uphold a finding based on inherently improbable
    evidence or evidence that is irrelevant to the issues before us. [Citation.]”
    [Citation.]’ (Richardson v. City and County of San Francisco Police Com.
    (2013) 
    214 Cal.App.4th 671
    , 692.)” (Daugherty v. City and County of San
    Francisco (2018) 
    24 Cal.App.5th 928
    , 944.)
    In particular, “expert testimony does not constitute substantial
    evidence when based on conclusions or assumptions not supported by
    evidence in the record (Hongsathavij v. Queen of Angels etc. Medical
    Center (1998) 
    62 Cal.App.4th 1123
    , 1137), or upon matters not reasonably
    relied upon by other experts (Pacific Gas & Electric Co. v. Zuckerman (1987)
    
    189 Cal.App.3d 1113
    , 1135). Further, an expert’s opinion testimony does not
    achieve the dignity of substantial evidence where the expert bases his or her
    20
    conclusion on speculative, remote, or conjectural factors. (Leslie G. v. Perry &
    Associates (1996) 
    43 Cal.App.4th 472
    , 487.) When the trial court accepts an
    expert’s ultimate conclusion without critically considering his or her
    reasoning, and it appears the conclusion was based on improper or
    unwarranted matters, we must reverse the judgment for lack of substantial
    evidence. (Pacific Gas & Electric Co. [at p.] 1136.) On the other hand, the
    trial court is free to reject testimony of a party’s expert, so long as the trier
    does not do so arbitrarily. (Howard v. Owens Corning (1999) 
    72 Cal.App.4th 621
    , 633.)” (People ex rel. Brown v. Tri-Union Seafoods, LLC (2009)
    
    171 Cal.App.4th 1549
    , 1567–1568.)
    We turn first to the trial court’s conclusion that a laboratory test
    finding a high level of mercury in one unit of a skin-lightening cream is an
    insufficient basis for concluding other units of the same product contain
    mercury. All the relevant experts—Steinberg, Solomon, and Sheehan—
    agreed that because of potential variability in factors such as ingredients,
    supply sources, manufacturing processes, and storage conditions, multiple
    samples would have to be tested to ensure consistency of a product within a
    batch and across multiple batches. Such testing would be necessary, all
    agreed, to determine matters such as the amount of an intentional ingredient
    or presence of a contaminant.
    The question in the present case, however, is whether the test results
    for one unit of a product could be sufficient to determine whether mercury
    was present in other units—not whether any specific amount was present,
    just whether it was present at all. Lee’s experts testified that answering this
    “yes/no” question did not require testing more than one unit of each product,
    or considering variables such as manufacturing and packaging procedures,
    because the amount of mercury in the unit tested was so high that it
    21
    demonstrated mercury was the intentionally added active ingredient—the
    ingredient used to achieve the product’s intended purpose. Because it was
    the active ingredient, while there might be variation in the actual
    concentration of mercury from one unit or batch to another, there would not
    be units in which mercury was completely absent. Significantly, Sheehan,
    too, agreed that the levels of mercury found in the tested samples indicated it
    was an intentional ingredient, not a contaminant.
    In rejecting Solomon’s and Steinberg’s conclusions as to generalizing
    the test results, the trial court first cited the deposition testimony of
    Dr. Brian Lee, who Lee had identified as an expert witness but did not
    present as a witness at trial, that “there is insufficient information to
    conclude that any untested unit contains mercury.”
    Dr. Lee testified at his deposition that his only assignment for this case
    was to determine “how much an exposure might occur to users.” Asked
    whether he would be offering an opinion that any unit of a product at issue in
    the case contained mercury other than the 11 samples for which he was given
    lab test results, Dr. Lee first clarified that the questioner meant “all of the
    other units that are on the market,” then responded, “No. I only know what
    is in these products. These may represent what’s in the other products, but
    until you actually test what is in the products, there could be several
    batches.”
    The trial court’s summary of Dr. Lee’s deposition testimony makes it
    appear more definitive than it actually was. The questioner explained he was
    asking about “units” of a product, not “product,” but Dr. Lee’s response
    referred to “products,” suggesting he was saying the products tested might or
    might not represent other products, not necessarily that one unit of a given
    product might or might not represent other units of that product (although
    22
    his references to “batches” creates some ambiguity). Moreover, especially in
    light of his assignment to determine “how much an exposure might occur to
    users,” the deposition excerpt read into the record at trial does not make clear
    whether Dr. Lee understood the question as asking about absolute presence
    or absence of mercury across units of a given product or about potential
    variability in the amount of mercury in one unit as compared to another, or
    whether he considered the significance, if any, of mercury being the active
    ingredient in the creams.
    Dr. Sheehan was expressly asked whether it made any difference to
    him that mercury was an intentionally added ingredient and testified that it
    did not. His response, while not entirely clear, appears to concern variability
    among batches without explaining how variability would extend to complete
    absence of the product’s active ingredient. 17 The trial court summarized
    Dr. Sheehan’s testimony as stating that “there is variation in the mercury
    content of skin-lightening creams, even when one expects to find mercury,
    and that a scientific method is needed to generalize from one unit to other
    units and other batches.” But as far as we are aware, Dr. Sheehan did not
    explain why this is so in the case of a product intended to address cosmetic
    issues for which mercury is an effective treatment and demonstrated—albeit
    in one or a small number of samples—to contain such high levels of mercury
    that it must be an intentional ingredient.
    17 Dr. Sheehan responded, “For the same general reason that I gave for
    the other, that is if you look at the literature, is if you find in one batch no
    skin-lightening creams and in another batch, you find some measurable
    added level of skin-lightening creams, it suggests that any measurement in
    one batch. It will not tell you what is happening within the population of
    that skin-lightening cream.”
    23
    The portions of Steinberg’s testimony that the trial court saw as
    contradicting his own and Solomon’s testimony that the test results could be
    generalized to the product line from which the sample was taken are not, in
    fact contradictory. The court noted Steinberg’s testimony that “at least three
    or four tests per batch would be needed to ensure uniformity of a cosmetic
    product,” that in order to predict consistency across units and batches, it is
    necessary to know whether a product was manufactured according to current
    cGMPs, and that, in effect, he did not expect cGMPs were followed for the
    products at issue. This testimony, however, addressed uniformity and
    consistency of the product. Steinberg expressly distinguished the testing
    necessary to ensure uniformity and consistency from that necessary to
    determine whether mercury is present in units of a specific skin-whitening
    product other than the unit tested where mercury is known to be the active
    ingredient in skin-whitening products because of its effectiveness in
    lightening skin, is the single ingredient known to also treat acne, as
    advertised for some of the creams at issue, and is found in high
    concentrations in one or a few samples of that specific skin-lightening
    product.
    Amazon’s statement that this is “a rare case where all experts on both
    sides agreed that it was not possible to extrapolate test results from a single
    unit of four products to all other units of that product line” is thus divorced
    from the record. This was Dr. Sheehan’s testimony, but not Dr. Solomon’s or
    Steinberg’s; Lee’s witnesses both testified that in the circumstances here, the
    tests could be generalized to other units of the product line from which the
    tested sample was taken.
    The trial court also noted that the National Food Lab’s report for the
    samples of Monsepa creams tested for the California Department of Justice
    24
    in 2013 contained the comment, “Please note that these results apply only to
    the sample(s) submitted for this report. Samples from a different portion of
    the same lot may produce different results.” This comment, again, refers to
    the undisputed potential for variability in uniformity and consistency across
    lots. It does not address the disputed question whether test results finding a
    high level of the active ingredient in a single sample can be generalized to
    conclude all samples of that product will have some amount of the active
    ingredient.
    Finally, the trial court noted that the RAPEX notices “delineate batch
    numbers of any product involved within the notice(s).” The observation is
    only partially accurate. The RAPEX notice for Face Fresh Beauty Cream
    provided information in the spaces for “Type/number of model” and “Batch
    number/Barcode,” 18 but the RAPEX notice for Faiza No. 1 Beauty Cream, in
    these spaces, stated “Unknown.” Moreover, the warning issued and report of
    action taken for both RAPEX notices pertained to “the product,” unlimited by
    batch number or otherwise. Both notices, for “Risk description,” stated that
    “[t]he product poses a chemical risk because it contains mercury” and “[t]he
    product does not comply with the Cosmetics directive 76/768/EEC.” Both
    notices reported the “[m]easures adopted by notifying country” as “Voluntary
    measures: Withdrawal of the product from the market.”
    In sum, the trial court’s stated reasons for concluding that a laboratory
    test finding a high level of mercury in one unit of a skin-lightening cream is
    an insufficient basis for inferring other units of the same product contain
    mercury do not withstand scrutiny. The only evidence directly supporting
    18The RAPEX notice for Face Fresh Beauty Cream, for “Type/number
    of model,” stated, “Unknown Batch number: No 1192 - MFG 1 3 12 EXP 1 3
    14” and for “Batch number/Barcode” stated, “1 41960 001908.”
    25
    the trial court’s conclusion, Dr. Sheehan’s testimony, failed to explain the
    basis for his rejection of the other experts’ distinction between testing to
    determine uniformity and consistency of a product and testing to confirm the
    absolute presence or absence of the active ingredient in a product. Indeed,
    Dr. Sheehan’s testimony on this point was inconsistent with the design of his
    own investigation of asbestos in talcum powder. Dr. Sheehan acknowledged
    that a study he conducted on whether users of talcum powder in the 1960’s
    and 1970’s were exposed to asbestos reported on the health risk from using
    talcum powder during that period based on analysis of five individual
    containers, each a different product. These five samples of five different
    products were the basis for what appears to be a broad conclusion in an
    article published in the peer-reviewed scientific literature that “[t]he absence
    of detectable asbestos fibers confirms the previous findings that most
    historical cosmetic talcum powder products did not produce asbestos fiber
    exposures.” Additionally, while Solomon and Steinberg both had
    considerable experience with the specific subject of testing here—mercury in
    skin-lightening creams—Sheehan did not recall having worked on a cream
    applied to the body other than sunscreen and had no experience with
    mercury in cosmetics or heavy metals in creams.
    Dr. Sheehan’s testimony is also difficult to reconcile with the practice of
    governmental entities responsible for regulating harmful consumer products.
    A CDPH employee who helped write the January 2014 news release warning
    against use of certain skin-lightening creams testified that the sample of
    Monsepa Express Peeling cream that was the basis for the alert did not have
    batch or lot numbers or other such identifying information and the alert was
    issued “for any and all products that have this appearance in name.”
    Dr. Solomon testified that “it’s something regulatory agencies not
    26
    infrequently will do based on a single sample or very few samples.” This
    makes obvious sense where the issue is whether a product contains the
    chemical in question at all, and not the precise amount in any individual
    unit.
    Proposition 65 imposes a duty to warn based on presence of a listed
    chemical in a product, without requiring uniformity across individual units in
    the precise amount of the chemical in a given unit. When the chemical at
    issue is the product’s active ingredient, its complete absence in an individual
    unit would be fortuitous. “Proposition 65 is a ‘right to know’ statute
    requiring companies that expose consumers to carcinogens or reproductive
    toxins to provide a reasonable and clear warning. (Health & Saf. Code,
    § 25249.6.) It is a remedial law, designed to protect the public, and thus we
    construe its provisions broadly to accomplish that protective purpose. (People
    ex rel. Lungren v. Superior Court (1996) 
    14 Cal.4th 294
    , 314.)” (Center for
    Self-Improvement & Community Development v. Lennar Corp. (2009)
    
    173 Cal.App.4th 1543
    , 1550–1551.) Once it is confirmed that a product
    contains a high level of a chemical listed as a toxin under Proposition 65 as
    an intentional ingredient (not as a contaminant), it would be inconsistent
    with the statutory purpose to require the kind of testing necessary to ensure
    product uniformity or consistency before enforcing the duty to warn.
    Amazon’s assertion that there was no evidence mercury was an
    intentional ingredient in these products is without basis in the record and
    directly inconsistent with even its own expert’s testimony: Sheehan fully
    agreed that mercury was present in the samples tested in amounts
    demonstrating it was an ingredient, not a contaminant. Amazon points to
    the CDPH testing that found most skin-lightening creams on the California
    market did not contain mercury, but that does not refute the undisputed
    27
    evidence that the products at issue here tested positive for mercury, at very
    high levels.
    Given the undisputed evidence that samples of five skin-lightening
    products purchased on Amazon’s Web site contained high levels of mercury as
    an intentionally added ingredient, there is no basis for a conclusion that Lee
    failed to prove this element of his case with respect to these products, at a
    minimum. If Lee proved the other elements of his claim, it cannot be
    rejected—at least for these specific products—on the ground that he failed to
    prove the products contained mercury.
    Beyond the products tested, a question remains. The trial court
    concluded Lee did not prove each of the 27 products listed by ASIN in the
    second amended complaint contained mercury because the evidence did not
    establish that they were the same products as the ones 19 tested. Lee
    subsequently limited his claims to 11 products that he claimed were the same
    as those tested despite having been assigned different ASINs. Given our
    rejection of the trial court’s conclusion that Lee failed to prove the tested
    products contained mercury, if the remaining elements of his claims were
    also established as to these specific products, the trial court will have to
    determine whether the untested products within the identified group of 11
    were in fact the same products as the ones tested.
    II.
    As earlier stated, Proposition 65 provides that “[n]o person in the
    course of doing business shall knowingly and intentionally expose any
    19The trial court referred to four products having been tested for this
    case. As earlier indicated, five samples were tested, one each for the Faiza,
    Monsepa, and Face Fresh creams, and two for Meiyong skin-lightening
    creams with the same name but assigned different ASINs on Amazon’s Web
    site.
    28
    individual to a chemical known to the state to cause cancer or reproductive
    toxicity without first giving clear and reasonable warning to such individual,
    except as provided in Section 25249.10.” (Health & Saf. Code, § 25249.6,
    italics added.) Lee argues the trial court erred in requiring him to prove
    Amazon had actual knowledge that the products at issue contained mercury,
    maintaining that constructive knowledge is sufficient to trigger the duty to
    provide Proposition 65 warnings. In general, “[p]roof of actual knowledge
    focuses on what information a defendant must have been aware of, while
    proof of constructive knowledge rests on a defendant’s duty to discover
    information.” (People v. ConAgra Grocery Products Co. (2017) 
    17 Cal.App.5th 51
    , 84–85.) “Constructive knowledge” means “[k]nowledge that one using
    reasonable care or diligence should have, and therefore that is attributed by
    law to a given person.” (Black’s Law Dict. (11th ed. 2019) p. 1043, col. 1;
    Castillo v. Toll Bros., Inc. (2011) 
    197 Cal.App.4th 1172
    , 1197.)
    Proposition 65 does not define the term “knowingly.” (See Health &
    Saf. Code, § 25249.11 [“Definitions”].) The regulations define the term as
    follows: “ ‘Knowingly’ refers only to knowledge of the fact that a discharge of,
    release of, or exposure to a chemical listed pursuant to Section 25249.8(a) of
    the Act is occurring. No knowledge that the discharge, release or exposure is
    unlawful is required. However, a person in the course of doing business who,
    through misfortune or accident and without evil design, intention or
    negligence, commits an act or omits to do something which results in a
    discharge, release or exposure has not violated [Health and Safety Code]
    Section 25249.5 or 25249.6 of the Act.” (Regs., §§ 25102, subd. (n), 25600.1,
    subd. (h).) Neither Proposition 65 nor the regulations use the phrase
    “constructive knowledge” or language commonly associated with the concept,
    29
    such as “should know” or “reason to know.” Nor do Proposition 65 or the
    regulations applicable to this case use the phrase “actual knowledge.” 20
    The trial court provided little explanation of its determination that
    Proposition 65 requires proof of actual knowledge. In granting Amazon’s
    motion in limine to exclude evidence of constructive knowledge, the court
    cited the “statute itself” and “the nature of the Prop 65 process including the
    notice aspects.” In its statement of decision, the court stated, “Proposition 65
    and its terms apply only to ‘businesses that know they are putting one of the
    chemicals into the environment.’ (See Nicolle-Wagner v. Deukmejian (1991)
    
    230 Cal.App.3d 652
    , 659 [quoting with approval language from ballot
    argument in favor of Proposition 65].)”
    Nicolle-Wagner v. Deukmejian, supra, 
    230 Cal.App.3d 652
     (Nicolle-
    Wagner) was not concerned with the nature of the knowledge requirement in
    Proposition 65 and does not discuss any distinction between actual and
    constructive knowledge. The question in that case was whether Proposition
    65 was intended to apply to naturally occurring carcinogens and reproductive
    toxins in food. Holding it was not, the court described the statutory language
    and ballot arguments for and against Proposition 65 as indicating the
    measure “sought to regulate toxic substances which are deliberately added or
    put into the environment by human activity. . . . [¶] . . . . [T]he ballot
    argument in favor of Proposition 65 explains that ‘[Proposition 65] will not
    take anyone by surprise. [It] applies only to businesses that know they are
    putting one of the chemicals out into the environment . . . .’ (Italics in
    original.)” (Nicolle-Wagner, at p. 659.) While the emphasis on “know,” in
    20 As will be further discussed, a regulation adopted subsequent to the
    sales of the products at issue in this case refers to “actual knowledge” in
    limiting the situations in which retail sellers are required to provide
    warnings. (Regs., § 25600.2, subd. (e).)
    30
    context, might naturally be understood by a layperson as implying actual
    knowledge, in legal terms “ ‘knowledge’ encompasses both actual knowledge
    and constructive knowledge.” (Tsasu LLC v. U.S. Bank Trust, N.A. (2021)
    
    62 Cal.App.5th 704
    , 718 (Tsasu).) 21
    Lee relies heavily on a 1988 agency interpretation of the statutory
    “knowingly and intentionally” language as including constructive
    knowledge. 22 “An administrative agency has the power to adopt regulations
    to effectuate the statutory purpose, provided the regulations are not in
    conflict with applicable statutes. (Woods v. Superior Court (1981) 
    28 Cal.3d 21
     The Tsasu court was called upon to determine whether the term
    “knowledge” in a provision of the Quiet Title Act meant solely actual
    knowledge or included constructive knowledge as well. Its first reason for
    adopting the later interpretation was that inclusion of constructive
    knowledge was “the result dictated by the statute’s plain language.
    ([Citation]. [Civ. Code,] § 764.060 uses the term ‘knowledge,’ and ‘knowledge’
    encompasses both actual knowledge and constructive knowledge.
    [Citations].)” (Tsasu, supra, 62 Cal.App.5th at p. 718.)
    22 Lee also relies on the provisions in the regulation defining
    “knowingly” that “[n]o knowledge that the discharge, release or exposure is
    unlawful is required” and “a person in the course of doing business who,
    through misfortune or accident and without evil design, intention or
    negligence, commits an act or omits to do something which results in a
    discharge, release or exposure has not violated [Health and Safety Code]
    Section 25249.5 or 25249.6 of the Act.” (Regs., §§ 25102, subd. (n), 25600.1,
    subd. (h).) Lee observes that this regulation “contemplates that ‘negligence’
    is actionable,” but does not further explain how the definition bears on the
    question of actual versus constructive knowledge. The inference that
    constructive knowledge is sufficient if negligence is actionable makes obvious
    sense where the negligence is with respect to awareness of the presence of a
    listed chemical in a product (i.e., if the defendant, in the circumstances,
    should have known the chemical was present and remained ignorant due to
    negligence, a warning would be required). The inference seems less clear,
    however, if the negligence is in regard to exposure (e.g., selling the product).
    In any event, we do not see this point as critical to our analysis.
    31
    668, 679; Nicolle–Wagner, supra, 230 Cal.App.3d [at p.] 658.) We defer to the
    technical skill and expertise of the administrative agency in interpreting the
    statutes. (Ibid.)” (Mission Community Hospital v. Kizer (1993) 
    13 Cal.App.4th 1683
    , 1691.)
    The agency initially responsible for implementing Proposition 65, 23 in
    its November 1988 Revised Final Statement of Reasons for what was then
    section 12601 of title 22 (now tit. 27, § 25601) of the California Code of
    Regulations, interpreted the Proposition 65 requirement that exposures be
    “knowing and intentional” before a warning is required “to include exposures
    about which there is constructive knowledge.” (OEHHA, Revised Final
    Statement of Reasons, 22 California Code of Regulations, Division 2 (Nov.
    1988), p. 39 (1988 FSOR).)
    Amazon points out that this section of the 1988 FSOR was discussing
    environmental exposures, which are distinct from consumer product
    exposures. But the agency’s statement about constructive knowledge was not
    limited to environmental exposures. While it happened to be made in a
    section discussing environmental exposures, as it was responding to a
    comment about the definition of such exposures, the “knowing and
    intentional” language applies to all exposures, not just environmental ones. 24
    23 The Governor originally designated the Health and Welfare Agency
    as the “lead agency” for Proposition 65, with authority to “adopt and modify
    regulations, standards, and permits, as necessary, in order to conform with
    and implement the purposes of the initiative statute.” (Nicolle-Wagner,
    supra, 230 Cal.App.3d at p. 655.) The California Environmental Protection
    Agency’s Office of Environmental Health Hazard Assessment (OEHHA) was
    designated the lead agency for implementation of Proposition 65 in 1995.
    (Regs., § 25102, subd. (o); Health & Saf. Code, § 25249.12, subd. (a).)
    At the time, the regulation defined “ ‘environmental exposures’ as
    24
    those which may foreseeably occur as the result of contact with an
    environmental medium . . . .” (1988 FSOR, supra, p. 39.) In response to a
    32
    Other portions of the 1988 FSOR also discuss constructive knowledge, thus
    making clear that the agency interpretation was not limited as Amazon
    suggests. 25
    concern that “requiring exposures to be foreseeable detracts from the
    requirement that exposures be knowing and intentional before a warning is
    required,” the agency explained that it interpreted the “knowing and
    intentional” requirement to include constructive knowledge and its “[u]se of
    the term ‘foreseeable’ is intended to define the limits of that constructive
    knowledge and of exposures for which businesses can reasonably be held
    responsible.” (Id. at pp. 39–40.) The current regulations do not include the
    terms “foreseeable” or “foreseeably” in the definition of “environmental
    exposure,” providing simply that such exposure means “an exposure that
    occurs as the result of contact with an environmental source . . . .” (Regs.,
    § 25600.1, subd. (f).) The definition of “consumer product exposure” included
    “reasonably foreseeable use of a consumer good,” and still does. (1988 FSOR,
    p. 8; Regs., § 25600.1, subd. (e).)
    25 Regarding the statutory phrase “discharge or release into water or
    onto or into land” in Health and Safety Code section 25249.5, the agency had
    proposed a regulation regarding liability when a person in the course of doing
    business transfers a chemical to a person authorized to receive it, which a
    commentor viewed as an attempt to impose vicarious liability on a transferor
    who has no control over the transferee. (OEHHA, Final Statement of
    Reasons, 22 California Code of Regulations, Division 2, Safe Drinking Water
    and Toxic Enforcement Act of 1983 (R-48-87) § 12101 et seq. (Jan. 1988) p. 26
     [as of
    Mar. 11, 2022]; see Regs., § 25102, subd. (f).) The agency modified the
    proposed regulation to provide that “discharge or release” to a source of
    drinking water includes transfer “for the principal purpose of disposing of the
    chemical to land or water in a manner which, if committed by the transferor
    would violate § 25249.5” and explained: “This proposal does not impose
    vicarious liability for acts over which the transferor has no control. In fact,
    this provision envisions that the transferor knows or reasonably should know
    that the transferee will make an otherwise prohibited discharge, and can
    control that behavior simply by not making the transfer. Further, this
    provision does not conflict with the requirement that discharges or releases
    prohibited under the Act be committed ‘knowingly.’ The transferor would
    still have actual or constructive knowledge of the discharge of the listed
    chemical.” (1988 FSOR, p. 27; see Regs., § 25102, subd. (f), italics added.)
    33
    Amazon does not expressly argue the agency has disavowed the general
    interpretation of “knowingly and intentionally” as including constructive
    knowledge. Instead, it points to a regulation adopted by OEHHA in 2016
    which it says “clarif[ies] that ‘knowledge’ for downstream entities means
    actual knowledge.” As relevant here, Regulations section 25600.2,
    subdivision (e) provides: “The retail seller is responsible for providing the
    warning required by Section 25249.6 of the Act for a consumer product
    exposure only when . . . [¶] . . . [¶] [t]he retail seller has actual knowledge of
    the potential consumer product exposure requiring the warning, and there is
    no manufacturer, producer, packager, importer, supplier, or distributor of the
    product who: [¶] . . . [i]s a ‘person in the course of doing business’ under
    Section 25249.11(b) of the Act, and [¶] . . . [h]as designated an agent for
    service of process in California, or has a place of business in California.”
    (Regs., § 25600.2, subd. (e)(5), italics added.) “Actual knowledge,” for
    purposes of this regulation, means “the retail seller receives information from
    any reliable source that allows it to identify the specific product or products
    that cause the consumer product exposure. Such knowledge must be received
    by the retail seller, its authorized agent or a person whose knowledge can be
    imputed to the retail seller. (Regs., § 25600.2, subd. (f)(1).) Further, “[w]here
    the source of a retail seller’s knowledge is a notice pursuant to Section
    25249.7(d)(1) of the Act, the retail seller shall not be deemed to have actual
    knowledge of any consumer product exposure alleged in the notice until five
    business days after the retail seller receives the notice. The notice must
    provide sufficient specificity for the retail seller to readily identify the
    product or products subject to the notice, in accordance with Article 9, section
    25903(b)(2)(D).” (Regs., § 25600.2, subd. (f)(2).)
    34
    These regulations were adopted in furtherance of the statutory
    directive in Health and Safety Code section 25249.11, subdivision (f), that
    “[i]n order to minimize the burden on retail sellers of consumer products
    including foods, regulations implementing Section 25249.6 shall to the extent
    practicable place the obligation to provide any warning materials such as
    labels on the producer or packager rather than on the retail seller, except
    where the retail seller itself is responsible for introducing a chemical known
    to the state to cause cancer or reproductive toxicity into the consumer product
    in question.” (OEHHA, Final Statement of Reasons, Title 27, California Code
    of Regulations, Proposed Repeal of Article 6 and Adoption of New Article 6,
    Regulations for Clear and Reasonable Warnings (2016) p. 35 (2016 FSOR).)
    The agency stated, “By adopting these new regulations, OEHHA
    intends to address many of the issues that have surfaced since the original
    regulations were adopted in 1988 by clarifying the relative responsibilities of
    manufacturers and others in the chain of distribution for products that are
    eventually sold at retail . . . .” (2016 FSOR, supra, p. 9.) As to retail sellers,
    the agency explained, Regulations “Section 25600.2 is based on the premises
    that (1) the consumer must receive the warnings mandated by [Health and
    Safety Code] Section 25249.6 of the Act before being exposed to a chemical
    known to cause cancer or reproductive toxicity; and (2) the primary
    responsibility for providing the warning for products, including foods, is with
    the manufacturer, producer, packager, importer, or distributor of those
    products. The regulations therefore recognize that those parties are
    primarily responsible for providing warnings. This is reasonable, as
    manufacturers usually will have greater knowledge than retailers of a
    product’s chemical content and whether it causes chemical exposures that
    require a warning.” (2016 FSOR, p. 35.)
    35
    Amazon, in the trial court, argued it was not a retail seller, and Lee
    therefore maintains Amazon forfeited any claim to the contrary and cannot
    rely upon the actual knowledge requirement pertaining to retail sellers.
    Amazon continues to argue it was not part of the chain of distribution at all
    and consequently was not responsible for providing Proposition 65 warnings,
    but adds that “[a]ssuming arguendo that Amazon is subject to this duty, the
    only classification that could apply is the end of the chain—i.e., the ‘retail
    seller.’ ”
    The trial court found it unnecessary to determine whether Amazon is a
    retail seller or whether Regulations section 25600.2, subdivision (e), applies
    retroactively to this case (as the product sales at issue preceded the 2016
    amendments) because of the broad definition of parties required to provide
    Proposition 65 warnings (“person in the course of doing business”) and the
    fact Amazon did not claim to be a “retail seller” without responsibility for
    warnings pursuant to the 2016 regulation (Regs., § 25600.2, subd. (e)). Yet
    the court relied on the definition of “actual knowledge” in this regulation in
    finding Lee failed to establish Amazon had actual knowledge that the
    products contained mercury.
    The trial court was clearly correct to reject Amazon’s claim to be
    outside the chain of distribution. Proposition 65 imposes the duty to provide
    warnings on any “person in the course of doing business,” which
    unquestionably includes Amazon’s activities here. As the trial court
    explained, “there is no language in section 25249.l l(f) [‘definitions’ for
    Proposition 65] or the new regulations expressly limiting the duty to provide
    a Proposition 65 warning only to a ‘manufacturer, producer, packager,
    importer, supplier, or distributor of a product,’ or a ‘retail seller’ (under more
    limited circumstances described in C.C.R. § 25600.2(e)), or limiting the broad
    36
    language in the operative statute imposing the warning requirement on any
    ‘person in the course of doing business’ who ‘knowingly and intentionally
    expose[s] any individual’ to a listed chemical. (Health & Saf. Code § 25249.6.)
    The phrase ‘person in the course of doing business’ is broadly worded and not
    limited to parties in the chain of distribution of a product or whose status is
    defined in the regulations. (See Health & Saf. Code, § 25249.11(b).)” Amazon
    manages and oversees all aspects of third-party sales on its Web site,
    including accepting payment and providing refunds to customers on sellers’
    behalf, providing the only channel for communication between customers and
    sellers, earning fees from sellers for each completed sale and, for sellers
    utilizing the FBA program, storing the products and arranging for their
    delivery to customers. There can be no question Amazon was, in the words of
    one court, “pivotal in bringing the product here to the consumer.” (Bolger v.
    Amazon.com (2020) 
    53 Cal.App.5th 431
    , 438 (Bolger).)
    This leaves two questions regarding Amazon’s reliance on Regulations
    section 25600.2, subdivision (e): Does the regulation even apply to this case,
    in which the salient events preceded adoption of the regulation? And, if so, is
    Amazon a “retail seller” within the meaning of the regulation?
    The 2016 regulations became operative on August 30, 2018
    ( [as of Mar. 11, 2022]). Although the product sales at
    issue in this case predated even the date the regulations were adopted, much
    less their operative date, Amazon argues the regulations apply retroactively
    because they simply clarified existing law. Western Security Bank v. Superior
    Court (1997) 
    15 Cal.4th 232
     (Western Security), the authority Amazon relies
    upon, explains that while “statutes do not operate retrospectively unless the
    Legislature plainly intended them to do so,” “a statute that merely clarifies,
    37
    rather than changes, existing law does not operate retrospectively even if
    applied to transactions predating its enactment.” (Id. at p. 243.)
    Western Security involved a conflict between the antideficiency statute
    prohibiting judgments for any loan balance remaining after a lender’s
    nonjudicial foreclosure and the rule that the obligation of the issuer of a
    letter of credit is independent of any underlying contract between the issuer’s
    customer and the letter’s beneficiary. After a Court of Appeal ruled that the
    issuer of a letter of credit could decline to honor it after notice it would be
    used to satisfy a deficiency after a nonjudicial foreclosure sale, the
    Legislature adopted a bill expressly intended to abrogate the Court of Appeal
    decision and confirm the beneficiary’s right to rely upon both the real estate
    collateral and the letter of credit. Western Security held the new legislation
    had “no impermissible retroactive consequences” because the Legislature
    made clear it was “a clarification of the state of the law before the Court of
    Appeal’s decision,” intended to “apply to all existing loans secured by real
    property and supported by outstanding letters of credit.” (Western Security,
    supra, 15 Cal.4th at pp. 237–238.)
    The “clarification” provided by Regulations section 25600.2, subdivision
    (e), is entirely different. As we have said, the regulation was adopted as a
    means of implementing the Legislature’s directive that the agency adopt
    regulations minimizing the “burden on retail sellers of consumer products” by
    “to the extent practicable plac[ing] the obligation to provide any warning
    materials such as labels on the producer or packager rather than on the retail
    seller,” except as specified. (Health & Saf. Code, § 25249.11, subd. (f); 2016
    FSOR, supra, p. 35.) Prior regulations had not addressed the allocation of
    responsibility. OEHHA described Regulations section 25600.2 as “a new,
    mandatory regulation addressing the relative responsibility of product
    38
    manufacturers and others in the chain of distribution, versus the product
    retail seller.” (2016 FSOR, pp. 8–9.) The specific requirements of this new
    regulation “clarified” these relative responsibilities in the sense that they had
    not previously been spelled out, not as an expression of what had always been
    required. Given the high level of detail in the regulation—from delineation of
    the specific circumstances in which a retail seller is responsible for providing
    warnings to the definition of, and parameters for attributing, actual
    knowledge—it is impossible to view the regulation as merely clarifying the
    law that previously existed.
    Moreover, OEHHA chose to make the 2016 regulations operative two
    years after they were adopted. (Gov. Code, § 11343.4, subd. (b)(2).) 26 This
    two-year period is expressly addressed in regulations concerning “ ‘safe
    harbor’ ” warnings (warnings that comply with content and method of
    transmission requirements “that have been determined ‘clear and reasonable’
    by the lead agency”). (Regs., § 25600, subds. (a) & (b).) Subdivision (b) of
    section 25600 of the Regulations provides that a warning for a consumer
    product manufactured prior to August 30, 2018, is “deemed to be clear and
    reasonable if it complies with” the prior regulation. The 2016 FSOR
    explained that the two-year implemental period was intended to “avoid the
    difficulties and expense involved for manufacturers and retail sellers to locate
    all products bearing the old warnings.” (2016 FSOR, supra, pp. 13–14.) The
    delayed effective date applied to all the 2016 regulations, and is clearly
    26With specified exceptions, a regulation required to be filed with the
    Secretary of State becomes effective on the quarterly basis established in
    Government Code section 11343.4, subdivision (a). One of the exceptions is
    where “[a] later date is prescribed by the state agency in a written
    instrument filed with, or as part of, the regulation . . . .” (Gov. Code,
    § 11343.4, subd. (b)(2).)
    39
    inconsistent with any intent that the new regulations be applied
    retrospectively.
    Amazon, therefore, cannot rely on Regulations section 25600.2,
    subdivision (e), to support the trial court’s determination that Lee was
    required to prove actual knowledge.
    Nor does Regulations section 25600.2 indicate Proposition 65, in
    general, contains an actual knowledge requirement. In fact, the introduction
    of an express “actual knowledge” requirement for retail sellers in the 2016
    regulation is itself an indication that actual knowledge was not previously
    required to trigger the obligation to provide Proposition 65 warnings. By
    specifying that retail sellers are responsible for providing warnings only if
    they have actual knowledge of the potential consumer exposure (and no
    upstream entity can readily be compelled to provide the warning),
    Regulations section 25600.2, subdivision (e)(5), implicitly indicates there are
    circumstances in which constructive knowledge is sufficient to require
    provision of a warning. It is a familiar rule of statutory interpretation that
    “[a] construction making some words surplusage is to be avoided.” (Dyna-
    Med, Inc. v. Fair Employment & Housing Com. (1987) 
    43 Cal.3d 1379
    , 1387.)
    The same rules of construction apply to initiative measures. (Williams v.
    Superior Court (2001) 
    92 Cal.App.4th 612
    , 622.) If OEHHD viewed all
    references to knowledge in the Proposition 65 regulations as meaning actual
    knowledge, it would not have needed to include an express “actual”
    knowledge requirement in Regulations section 25600.2, subdivision (e). The
    purpose of this regulation was to distinguish retail sellers’ obligations from
    those of entities higher on the chain of distribution. One of the ways it does
    so is by requiring “actual knowledge” where the statutory phrase “knowingly”
    40
    would otherwise connote—and had been interpreted as including—actual or
    constructive knowledge.
    The critical question, of course, is whether the electorate intended
    “knowingly and intentionally” to mean solely actual knowledge or
    constructive knowledge as well. As we have said, because Proposition 65 is “a
    remedial law, designed to protect the public,” we construe its provisions
    “broadly to accomplish that protective purpose.” (People ex rel. Lungren v.
    Superior Court, 
    supra,
     14 Cal.4th at p. 314; Center for Self-Improvement &
    Community Development v. Lennar Corp., supra, 173 Cal.App.4th at
    pp. 1550–1551.)
    The preamble to Proposition 65, section 1 of the law proposed to the
    voters, makes clear the measure was driven by the voters’ desire for greater
    protection against hazardous chemicals, specifically including information
    about exposures, strict enforcement and deterrence of actions threatening
    public health and safety. The preamble states: “The people of California find
    that hazardous chemicals pose a serious potential threat to their health and
    well-being, that state government agencies have failed to provide them with
    adequate protection, and that these failures have been serious enough to lead
    to investigations by federal agencies of the administration of California’s
    toxic protection programs. The people therefore declare their rights: [¶] (a)
    To protect themselves and the water they drink against chemicals that cause
    cancer, birth defects, or other reproductive harm. [¶] (b) To be informed
    about exposures to chemicals that cause cancer, birth defects, or other
    reproductive harm. [¶] (c) To secure strict enforcement of the laws controlling
    hazardous chemicals and deter actions that threaten public health and safety.
    [¶] (d) To shift the cost of hazardous waste cleanups more onto offenders and
    less onto law-abiding taxpayers. [¶] The people hereby enact the provisions
    41
    of this initiative in furtherance of these rights.” (Ballot Pamp., Gen. Elec.
    (Nov. 4, 1986) text of Proposition 65, p. 53, italics added.) (Hereafter Ballot
    Pamp.)
    The public policy reflected in these findings and stated purposes
    militates in favor of an interpretation of the “knowingly and intentionally”
    requirement of Health and Safety Code section 25249.6 as including
    constructive knowledge. (See Tsasu, supra, 62 Cal.App.5th at p. 719
    [“defining ‘knowledge’ in [quiet title statute] to encompass both actual and
    constructive knowledge is the result dictated by public policy”].) Interpreting
    section 25249.6 to require warnings only when a person in the course of doing
    business has actual knowledge that he or she will expose any individual to a
    listed chemical would significantly limit the reach of the statute and create
    incentives to avoid information that might reveal potential sources of
    exposure.
    Tsasu offers an illustration, albeit in a different context. Pursuant to
    the statute at issue in that case, a third party acting in reliance on a quiet
    title judgment retains its property rights, even if that judgment is
    subsequently invalidated as void, if the third party “qualifies as a ‘purchaser
    or encumbrancer for value . . . without knowledge of any defects or
    irregularities in [the earlier quiet title] judgment or the proceedings.’ ([Code
    Civ. Proc.,] § 764.060.)” (Tsasu, supra, 62 Cal.App.5th at pp. 716–717.)
    Among its reasons for construing “knowledge” in the statute as including
    both actual and constructive knowledge, the Tsasu court explained that
    limiting “knowledge” to actual knowledge “creates wholly perverse incentives
    because it discourages prospective buyers from checking the record of title or
    from heeding ‘warning signs’ necessitating further inquiry—lest they acquire
    actual knowledge of a defect or irregularity with a quiet title judgment that
    42
    would strip them of section 764.060’s protection. Such incentives are inimical
    to the entire system of real property law in California, which places upon real
    estate buyers a duty to inquire into the validity of their prospective
    ownership claim [citation], and to heed—not ignore—any ‘ “reasonable
    warning signs” ’ [citations].” (Id. at pp. 719–720.) The court declined to
    interpret the statute as limited to actual knowledge, in part, because the
    statute was not intended to “encourage recklessness or willful ignorance.”
    (Id. at p. 720.)
    In the context of Proposition 65, limiting the obligation to provide
    warnings to actual knowledge would create incentives for businesses to avoid
    information that might alert them to the presence of hazardous chemicals
    and potential for exposures. This result would be inimical to the protective
    purpose of the law generally, and specifically to the voters’ stated purposes of
    furthering the dissemination of information about exposures to toxic
    chemicals, strict enforcement of laws controlling hazardous chemicals and
    deterrence of actions that threaten public health and safety. (Ballot Pamp.,
    supra, p. 53.)
    Amazon argues the trial court’s interpretation of Health and Safety
    Code section 25249.6 as requiring actual knowledge is supported by cases
    “confirm[ing] that a duty to disclose a fact cannot arise without actual
    knowledge of the fact.” The cases it relies upon, however, are not particularly
    helpful. In San Diego Hospice v. County of San Diego (1995) 
    31 Cal.App.4th 1048
    , the plaintiff sought recission of a release on a theory of fraudulent
    nondisclosure of facts the defendant of which the defendant allegedly had
    imputed knowledge. (Id. at p. 1055.) The court explained that in order to
    establish the duty to disclose underlying the claim, the plaintiff must show
    “the material fact is known to (or accessible only to) the defendant” and “the
    43
    defendant knows the plaintiff is unaware of the fact and cannot reasonably
    discover the undisclosed fact.” (Ibid.) Because the duty to disclose “requires
    some element of scienter—knowledge of the other party’s ignorance,” it could
    not arise if the material facts were not “actually known” to the defendant:
    “We cannot perceive how it is possible for a principal to know the other party
    is ignorant of something of which the principal is equally ignorant.” (Id. at
    pp. 1055–1056.) This reasoning, specific to the scienter element of the tort
    claim at issue, has no bearing on the meaning of the knowledge requirement
    in a statute requiring warnings of potential exposures to hazardous
    chemicals.
    The other case Amazon cites is no more apt. Santiago v. Firestone Tire
    & Rubber Co. (1990) 
    224 Cal.App.3d 1318
     involved employees’ claims under
    Labor Code section 3602, subdivision (b), which provides an exception to the
    general rule that workers’ compensation is the sole and exclusive remedy for
    injured workers, permitting an action for damages against the employer
    where the employee’s injury is aggravated by the employer’s “ ‘fraudulent
    concealment of the existence of the injury and its connection with the
    employment.’ ” (Santiago. at p. 1323.) Santiago held the employees were
    required to show the employer had actual knowledge of the employees’
    injuries and fact they were caused by their employment, rejecting the
    argument that constructive knowledge should apply based on a detailed
    analysis of the “history of Labor Code section 3602, the language of the
    statute, and the cases construing it.” (Id. at pp. 1331–1334.) Amazon quotes
    the Santiago court’s statement that “ ‘defendant obviously could not be
    charged with concealing matters which it did not know.’ ” (Id. at p. 1334.)
    But the issue in the present case is not concealment of facts, and the holding
    that fraudulent concealment necessarily requires actual knowledge says
    44
    nothing about the statutory meaning of “knowingly” with respect to the
    obligation to provide warnings of potential exposures under Proposition 65.
    There is nothing rationally or logically inconsistent with a requirement that a
    business provide warnings—or be liable for failure to do so—if it knows or
    has sufficient reason to know it is exposing “any individual” to a listed toxic
    chemical.
    Amazon finds support for its argument that Health and Safety Code
    section 25249.6 requires actual knowledge in the fact that this provision uses
    the phrase “knowingly and intentionally” while section 25249.5, which
    prohibits discharge of chemicals into water, uses only “knowingly.” Relying
    on the rules of statutory interpretation that instruct us to, if possible, give
    significance to every word and avoid a construction that renders some words
    surplusage (Moyer v. Workmen’s Comp. Appeals Bd. (1973) 
    10 Cal.3d 222
    ,
    230), Amazon argues we cannot ignore the inclusion of “intentionally” in
    Health and Safety Code section 25249.6. With this much, we agree. But we
    do not agree with Amazon’s conclusion that the phrase “knowingly and
    intentionally” “imposes a higher level of knowledge” than the word
    “knowingly” alone.
    As we have said, neither Proposition 65 nor the regulations define
    “intentionally.” “ ‘ “When a term goes undefined in a statute, we give the
    term its ordinary meaning.’ ” (De Vries v. Regents of University of California
    (2016) 
    6 Cal.App.5th 574
    , 590–591.) ‘In divining a term’s “ordinary
    meaning,” courts regularly turn to general and legal dictionaries.’ (Id. at
    p. 591; People v. Hodges (1999) 
    70 Cal.App.4th 1348
    , 1355.)” (Upshaw v.
    Superior Court (2018) 
    22 Cal.App.5th 489
    , 504.)
    There is overlap in dictionary definitions of the terms “knowingly” and
    “intentionally”; definitions of the former sometimes refer to the latter and
    45
    each is considered a synonym of the other. 27 But definitions of “knowingly”
    tend to focus on awareness 28 while definitions of “intentionally” tend to focus
    on purpose. 29
    27 For example, the Oxford English Dictionary (3d ed. 2015) (OED)
    includes “intentionally” in its definition of “knowingly” (OED Online
     [as of
    Mar. 11, 2022]); Merriam-Webster’s Thesaurus lists “intentionally” and
    “knowingly as synonyms for each other. (Merriam-Webster’s Thesaurus
    Online  [as of
    Mar. 11, 2022]; 
    [as of Mar. 11, 2022].)
    28  For example, “knowingly” is defined by the OED as “[w]ith
    knowledge or awareness (of what one is doing, of a fact, etc.); consciously,
    intentionally.” (OED Online
    
    [as of Mar. 11, 2022]) and by Merriam-Webster Unabridged Dictionary
    (Merriam-Webster) as “with awareness, deliberateness, or intention”
    (Merriam-Webster Dict. Online  [as of Mar. 11, 2022]). Black’s Law
    Dictionary defines “knowing” as “[h]aving or showing awareness or
    understanding; well-informed” and “[d]eliberate; conscious,” and “knowingly”
    as “[i]n such a manner that the actor engaged in prohibited conduct with the
    knowledge that the social harm that the law was designed to prevent was
    practically certain to result; deliberately.” It explains: “A person who acts
    purposely wants to cause the social harm, while a person who acts knowingly
    understands that the social harm will almost certainly be a consequence of
    the action, but acts with other motives and does not care whether the social
    harm occurs.” (Black’s Law Dict. supra, p. 1042, col. 2.)
    29 Examples include “with intention, on purpose” (OED Online
    
    [as of Mar. 11, 2022]) and “in an intentional manner: with intention:
    purposely” (Merriam-Webster Dict. Online  [as of Mar. 11, 2022). Black’s Law
    Dictionary, supra, page 965, defines “intentional” as “[d]one with the aim of
    carrying out the act.”
    46
    To give significance to each word used in Health and Safety Code
    section 25249.6, it is more reasonable to view “intentionally” as adding this
    concept of purpose than as giving “knowingly” a different meaning than it
    would have when used on its own. We see no basis for reading “intentionally”
    in section 25249.6 as essentially modifying “knowingly” to require a higher
    level of knowledge than “knowingly” would otherwise convey. As we have
    said, an actual knowledge requirement would narrow the scope of section
    25249.6, contrary to the purpose of Proposition 65. (See California
    Manufacturers & Technology Assn. v. State Water Resources Control Bd.
    (2021) 
    64 Cal.App.5th 266
    , 281–282 [statutory term with alternative
    definitions construed as intended to carry the meaning more consistent with
    legislative purpose].) The inclusion of “intentionally” in this statute, as
    opposed to section 25249.5, is an insufficient basis for the interpretation
    Amazon seeks. 30
    Finally, Amazon points to the absence in Proposition 65 of language
    often used to indicate a statute contemplates constructive knowledge. (E.g.,
    30 One explanation for the distinction in language between these two
    statutes might lie in the different degree of regulation each provides. Health
    and Safety Code section 25249.5 is an outright prohibition against
    contamination of drinking water. In prohibiting businesses from “knowingly”
    discharging or releasing listed chemicals into water or land where they
    probably will pass into a source of drinking water, this statute appears to
    contemplate liability when the business is aware that the discharge or
    release it causes contains the listed toxin and is likely to reach a source of
    drinking water, regardless of whether it intends this result. Health and
    Safety Code section 25249.5 is less restrictive, requiring warnings but not
    prohibiting the act that causes exposure to the chemical. In keeping with
    this lower level of regulation, the statutory requirement is triggered only
    where the defendant is not only aware but also intends to take the action that
    results in the exposure—in the case of a consumer product, intends to take
    the action that moves the product toward the consumer.
    47
    Labor Code, § 2810 [“A person or entity shall not enter into a contract or
    agreement for labor or services . . . where the person or entity knows or
    should know that the contract or agreement does not include funds sufficient
    to allow the contractor to comply with all applicable . . . laws . . .”]; Civ. Code,
    § 3426.1 [“ ‘Misappropriation’ means: [¶] (1) Acquisition of a trade secret of
    another by a person who knows or has reason to know that the trade secret
    was acquired by improper means”].) While the presence of such language
    may compel a conclusion that the statute encompasses constructive
    knowledge, its absence is not dispositive. (E.g., PacifiCare Life & Health Ins.
    Co. v. Jones (2018) 
    27 Cal.App.5th 391
    , 417–418 [upholding regulation
    defining “knowingly,” in statute delineating unfair and deceptive insurance
    business practices, as including constructive knowledge]; Tsasu, supra,
    62 Cal.App.5th at pp. 717–721 [construing “knowledge” in quiet title statute
    as including constructive knowledge].)
    We conclude the trial court erred in ruling that Lee was required to
    prove Amazon had actual knowledge the products at issue contained mercury
    and excluding evidence of constructive knowledge. Of course, this error
    would be of no consequence if Lee is correct that the record demonstrates
    substantial evidence of actual knowledge as a matter of law. Lee argues
    Amazon had actual knowledge of the mercury in the Faiza and Face Fresh
    skin-whitening creams from the RAPEX notices and for the Monsepa cream
    from Lee’s notice of violation. He does not contend Amazon had actual
    knowledge as to the Meiyong products.
    Lee’s argument is strongest with respect to the Monsepa cream. Lee
    asserts that a notice of violation necessarily establishes actual knowledge,
    citing the definition of Regulations section 25600.2, subdivision (f)(2), which
    expressly treats a notice of violation as a source of a retail seller’s actual
    48
    knowledge. 31 As we have said, Regulations section 25600.2 is not applicable
    to the present case. But “[p]roof of actual knowledge focuses on what
    information a defendant must have been aware of” (People v. ConAgra
    Grocery Products Co., 
    supra,
     17 Cal.App.5th at pp. 84–85), and the notice of
    violation was directly served on Amazon.
    Amazon does not dispute the general proposition that a notice of
    violation establishes actual knowledge, but it argues the notice in the present
    case was insufficient to do so. The notice of violation named Amazon and
    aztopselstore.com (the distributor of Monsepa cream) as violators, specified
    the chemical (“Mercury”), routes of exposure (“Ingestion, Dermal, Inhalation”)
    and type of harm (“Developmental Toxin”), and identified the products as
    “[s]kin-lightening creams” with “Monsepa Express Peeling Night Face
    Cream, 15 mL size” as an example. Amazon argues the reference to “[s]kin-
    lightening creams” did not provide notice as to any specific product, and the
    CDPH’s investigation, which found mercury in only seven of over a hundred
    skin-lightening creams tested, demonstrated most such creams do not contain
    mercury. Amazon further argues the fact that the notice of violation named
    “Monsepa Express Peeling Night Cream” was insufficient to establish
    knowledge because the product Lee had tested for this litigation has a
    31 The regulation states that “ ‘[a]ctual knowledge’ means the retail
    seller receives information from any reliable source that allows it to identify
    the specific product or products that cause the consumer product exposure”
    and “[w]here the source of a retail seller’s knowledge is a notice pursuant to
    [Health and Safety Code] Section 25249.7(d)(1) of the Act, the retail seller
    shall not be deemed to have actual knowledge of any consumer product
    exposure alleged in the notice until five business days after the retail seller
    receives the notice. The notice must provide sufficient specificity for the
    retail seller to readily identify the product or products subject to the notice, in
    accordance with Article 9, section 25903(b)(2)(D).” (Regs., § 25600.2,
    subd. (f)(1), (2).)
    49
    different name (“Monsepa Express Peeling” per packaging; “Monsepa Express
    Peeling Remove Dark Spots Face Cream” on Amazon listing).
    Amazon’s argument is not persuasive. As Lee points out, the
    regulations require a notice of violation to provide “the name of the consumer
    product or service, or the specific type of consumer product or services, that
    cause the violation, with sufficient specificity to inform the recipients of the
    nature of the items allegedly sold in violation of the law and to distinguish
    those products or services from others sold or offered by the alleged violator
    for which no violation is alleged.” (Regs., § 25903, subd. (b)(2)(D).) OEHHA
    has explained that this regulation is meant to avoid identification of the
    products at issue in “very broad terms, such as ‘various aerosol, paint,
    adhesive and/or automotive products, including but not limited to,’ ” that are
    “inadequate to describe the nature of the violation that is claimed.”
    (OEHHA, Final Statement of Reasons, Adopt Section 12908, Notices of
    Violation, title 22, Division 2, California Code of Regulations, p. 10.) On the
    other hand, the agency stated, “[c]learly it would be sufficient simply to say
    ‘aerosol spray paint,’ ‘car wax’ or ‘paint thinner.’ Such a description would at
    least identify the category of products that will be the subject of the action,
    and would enable the public agency to focus the investigation.” (Ibid.)
    Lee’s notice of violation satisfied these parameters. The notice of
    violation informed Amazon that a category of products—“skin-lightening
    creams”—allegedly caused exposure to mercury and specifically named one
    such product. Although the product Lee had tested was identified with a
    slightly different name on the Amazon Web site, the notice, Web site listing,
    and product packaging all used the distinctive “Monsepa Express Peeling”
    identifier. In our view, this constituted notice that the Monsepa skin-
    50
    lightening cream Lee put at issue here was alleged to contain mercury and,
    thus, was evidence of actual knowledge.
    In arguing Amazon had actual knowledge that the Faiza and Face
    Fresh creams contained mercury from the RAPEX notices for these products,
    Lee relies on Kosnoff’s testimony that Amazon employees in Europe review
    RAPEX notices; Amazon would have been aware of the 2013 RAPEX notice
    for Faiza Beauty Cream; and he was aware a “very similar” product was
    listed on the American Web site. This testimony is less definitive proof of
    actual knowledge than the evidence regarding the Monsepa cream: Kosnoff
    described a general business practice that would be expected to result in
    Amazon’s awareness of the RAPEX notices, but his testimony also raised
    questions about the relationship between and management of Amazon’s
    European and American Web sites which are not addressed by any evidence
    in the record. The RAPEX notices may well provide persuasive evidence of
    constructive knowledge, but we cannot find them sufficient to establish
    actual knowledge as a matter of law so as to overturn the trial court’s finding
    of no actual knowledge.
    Because the trial court precluded evidence of constructive knowledge,
    we have no means of evaluating whether Lee will be able to make a showing
    sufficient to alter the ultimate outcome of this case. 32 Evidence of
    32 In finding Amazon did not have actual knowledge that the skin-
    lightening creams contained mercury, the trial court noted that mercury was
    not identified as an ingredient on the packaging or product detail pages. Lee
    argues the absence of information on a product’s label cannot be the basis for
    finding an absence of actual knowledge, an argument also maintained by the
    Attorney General in his amicus brief; otherwise, Amazon could avoid liability
    even if it was informed by the third-party seller or any other reliable source
    that the product contained mercury. We do not read the trial court as having
    held the absence of information on the products’ packaging or product detail
    pages was dispositive of the actual knowledge issue; the court went on to say
    51
    constructive knowledge must be evaluated in the context of all relevant
    circumstances bearing on what Amazon had reason to know or reasonably
    should have known. This will presumably include facts related to Amazon’s
    business operations and role in bringing the products to customers as well as
    the statutory context.
    With regard to the latter, Health and Safety Code section 25249.11,
    subdivision (f), makes clear that the Legislature did not intend all parties
    involved in bringing a consumer product into the hands of the consumer to
    bear the same responsibility for providing the warnings required by
    Proposition 65 and, specifically, intended to minimize the burden on retail
    sellers in most cases. Amazon’s assertion that it is not a retail seller is part
    of its broader argument that it is not a part of the chain of distribution at all,
    and therefore not subject to section 25249.6. As we have said, this broader
    argument unsustainable. But Amazon’s fallback position—that if it is part of
    the chain of distribution, the only thing it can be considered is a retail
    seller—is not unreasonable. There is no evidence to support characterizing
    Amazon as a manufacturer, producer, packager, importer, or distributor of
    the products at issue. Regardless of whether it comes within ordinary
    definitions of “retail seller” or can be considered a “seller” if it does not take
    title of the product in question (see Milo & Gabby LLC v. Amazon.com, Inc.
    (Fed. Cir. 2017) 
    693 Fed. Appx. 879
    , 890 [Amazon not a “seller” for purposes
    of copyright infringement claim]), Amazon’s role in the present case was
    that Lee failed to establish Amazon had actual knowledge “at any earlier
    time,” perhaps a reference to evidence such as the RAPEX notices and CDPH
    notice. It should be obvious that while packaging indicating a listed toxin is
    an ingredient would supply actual knowledge, absence of such information on
    product labeling, in and of itself, is far too limited a basis for finding an
    absence of knowledge, actual or otherwise.
    52
    analogous to a retail seller’s for purposes of Health and Safety Code section
    25249.6 in that Amazon had nothing to do with determining the contents,
    manufacturing or labelling of the skin-lightening products. As OEHHA noted
    regarding the 2016 regulations, entities such as manufacturers, producers
    and packagers “usually will have greater knowledge than retailers of a
    product’s chemical content and whether it causes chemical exposures that
    require a warning.” (2016 FSOR, supra, p. 35.) Still, Amazon made the
    products available for purchase by the ultimate consumer and, at a
    minimum, facilitated the sale by providing a forum for it to take place,
    handling the finances of the transaction and controlling communications
    between the customer and the third-party sellers. All these facts may be
    relevant considerations with respect to what knowledge can be attributed to
    Amazon.
    III.
    The trial court found Lee failed to prove that Amazon exposed
    consumers to mercury because he did not prove anyone actually used the
    skin-lightening products at issue. The trial court noted that Lee “did not
    present any evidence of exposure related to any of the product purchasers,
    despite obtaining those purchasers’ contact information from Amazon during
    discovery”; the evidence established “there has been a public campaign to
    discourage the use of skin-lightening creams that may contain mercury,
    including a buy-back program for new and used products”; and “[t]here was
    no evidence that anyone was exposed to mercury in connection with any of
    the four units that were actually purchased by plaintiff’s counsel through
    Amazon’s marketplace.”
    Lee maintains the trial court’s interpretation of “expose” improperly
    narrowed the scope of Proposition 65, imposing a burden that would make it
    53
    all but impossible to enforce the law with respect to consumer products due to
    the expense of obtaining evidence that more than a minimal number of
    people opened and used a product they purchased. Lee points out that
    consumer products may be sold to millions of customers, many of whom may
    remain anonymous if the products were purchased in stores that do not keep
    records of individual purchasers or, if identifiable, may be unwilling to
    participate in litigation.
    Moreover, Lee argues, proof of individual consumers’ use of the
    products is unnecessary because common sense dictates a conclusion that
    people purchase products in order to use them. Lee and the Attorney General
    both point to the statutory maxim that “[t]hings happen according to the
    ordinary course of nature and the ordinary habits of life.” (Civ. Code, § 3546.)
    Thus, the Attorney General, drawing on his experience in enforcing
    Proposition 65, states he “always assumed that people who buy cookies eat
    them; people who buy sodas drink them; and people who buy skin creams
    apply them to their skin.” The Attorney General states, “companies do not
    sell products that their customers will not use, and consumers do not buy
    skin creams unless they intend to apply them to their skin. Accordingly, in
    his cases, the Attorney General has not provided declarations from
    consumers that they ate the lead-containing cookies, took the vitamins, or
    used the anti-diarrheal medicine that have been the subject of his Proposition
    65 claims” and no court has “ever even suggested that such evidence was
    necessary.” Indeed, as Lee points out, when Lee sought a preliminary
    injunction in this case, one of Amazon’s arguments in opposition was that the
    request was made two years after the complaint was filed and, “[b]ecause
    Amazon blocked the sale of the relevant Products long ago, the only
    54
    reasonable inference is that the Products have been completely used since
    they were last purchased.”
    The Proposition 65 regulations define “expose” as meaning “to cause to
    ingest, inhale, contact via body surfaces or otherwise come into contact with a
    listed chemical. An individual may come into contact with a listed chemical
    through water, air, food, consumer products and any other environmental
    exposure as well as occupational exposures.” (Regs., § 25102, subd. (i).) In
    article 6, “Clear and Reasonable Warnings,” “[c]onsumer product exposure” is
    defined as “an exposure that results from a person’s acquisition, purchase,
    storage, consumption, or any reasonably foreseeable use of a consumer
    product, including consumption of a food. (Regs., § 25600.1, subd. (e).) When
    this regulation was adopted in 2016, OEHHA’s FSOR included the statement,
    “If a person’s use of a product is ‘reasonably foreseeable’ even if it is not
    entirely consistent with label recommendations, any resulting exposures to
    listed chemicals can properly be considered to be ‘knowing and intentional’ on
    the part of the product manufacturer, and are therefore subject to Proposition
    65.” (2016 FSOR, supra, p. 31.)
    The trial court viewed the definition of “consumer product exposure” as
    requiring proof of an “actual ‘exposure’ ” and the agency’s explanatory
    statement as confirming that “foreseeability may impact knowledge and
    intent, but it does not eliminate the requirement of exposure.” In our view,
    however, the regulatory definition of “consumer product exposure” provides
    less insight into the meaning of “expose” as used in Health and Safety Code
    section 25249.6 than the trial court attributed to it. The explanatory
    statement the trial court noted was in response to a comment seeking to alter
    the definition of “consumer product exposure” by replacing the phrase “any
    reasonably foreseeable use of a product” with “use of a product in accordance
    55
    with recommendations made in the product’s labels or labeling or with other
    actual and accepted uses of the product” or “use of the product in accordance
    with the product labeling recommendations or ordinary conditions of use.”
    (2016 FSOR, supra, p. 31.) OEHHA rejected the proposed revision because it
    would “unnecessarily limit the potential exposure scenarios to listed
    chemicals” and “[l]imiting the scope of the definition would not be consistent
    with the Act.” (Ibid.) The foreseeability issue addressed in the agency’s
    statement pertained only to the “use” component of the provision defining
    “consumer product exposure,” serving to limit the extent to which a business
    subject to Proposition 65 is required to anticipate the ways its product might
    be used. No such clarification was necessary for the other sources of exposure
    listed in the regulation (purchase, acquisition, storage).
    The regulation defines “consumer product exposure” by describing the
    sources from which an exposure can result, but it does not define what
    “exposure” actually consists of. The phrase “consumer product exposure”
    appears in article 6 of the Act (“Clear and Reasonable Warnings”), in
    regulations describing the required contents of Proposition 65 warnings and
    methods by which they may be provided. (Regs., §§ 25601, 25602, 25603.)
    Regulations section 25600, subdivision (a), provides that “[n]othing in Article
    6 shall be interpreted to determine whether a warning is required for a given
    exposure under Section 25249.6 of the Act.” The original lead agency also
    distinguished between the definition of “consumer product exposure” and the
    definition of “expose” for purposes of Health and Safety Code section 25249.6.
    Responding to a comment that “consumer exposures are triggered by the
    purchase of a product, rather than by consumption,” the agency stated: “The
    definition of ‘consumer products exposure,’ however, is not intended to
    establish when an exposure occurs.· It is intended to address the availability
    56
    of the ‘safe harbor’ warning. The term ‘expose’ is defined elsewhere as
    meaning ‘to cause to ingest, inhale, contact via body surfaces or otherwise
    come into contact with a chemical.’ ” (Former Cal. Code Regs., tit. 22,
    § 12201, subd. (f) [now tit. 27, § 25102, subd. (i)].) “This could include the
    purchase by an individual of a product, not just the consumption of that
    product.” (1988 FSOR, supra, p. 10.) 33
    Arguing that this agency explanation “does not establish that an
    33
    exposure necessarily occurs only from a purchase,” Amazon points to
    statements in the 2016 FSOR which it says explain that “a person who
    purchases a product is not necessarily exposed” and “[i]n some cases,
    exposure will not occur until the product packaging is opened.”
    The first of these statements (italicized below) is part of a comment
    submitted to OEHHA regarding its proposed regulation defining “retail
    seller” (Regs., § 25600, subd. (l)): “In the definition for ‘retail seller,’ the term,
    ‘purchasers’ should be changed to ‘consumers,’ both for consistency and to
    avoid inadvertently including wholesale distributors. Often, the consumer of
    the product, and thus the individual who is exposed, is not the purchaser.”
    (2016 FSOR, supra, p. 33.) OEHHA responded that it agreed and had
    replaced the term “purchasers” with “consumers.” (Ibid.) Read in context, it
    is apparent that the point was to avoid language that might be taken as
    extending the regulation restricting circumstances in which retail sellers are
    required to provide Proposition 65 warnings to sellers that do not sell directly
    to consumers, not to suggest that sale to a consumer does not expose the
    consumer to a listed chemical in the product.
    The second statement (italicized below) is from the OEHHA’s response
    to a comment that a proposed regulation specifying methods for providing
    safe harbor consumer product exposure warnings (Regs., § 25602, subd. (a))
    was unclear as to “whether a warning is required on both the immediate
    container and the outer packaging of a product.” (2016 FSOR, supra, p. 87.)
    OEHHA responded in the negative, explained that the regulations provided
    several options for warnings, then stated, “[t]he warning should be placed in
    such a manner as to ensure that it is seen and understood prior to exposure.
    For example, . . . if a person will be exposed to a listed chemical immediately
    upon opening a product’s outer packaging through contact with the product,
    the warning should be placed on the outer container or wrapper.” (Ibid.) This
    guidance is obviously directed at those in a position to provide warnings on
    57
    Lee’s claim in the present case is that Amazon violated the requirement
    of Health and Safety Code section 25249.6 that a business shall not
    knowingly and intentionally “expose” any individual to a listed chemical
    without first providing clear and reasonable warning. The ordinary
    definition of “expose” is “[t]o lay open (to danger, ridicule, censure, etc.).”
    (OED, “expose” OED Online
     [as of Mar. 11, 2022]; Merriam-Webster Dict. Online, “expose” [“to
    lay open (as to attack, danger, trial, or test)”]  [as of Mar. 11, 2022].) The original lead
    agency expressly relied upon this general definition of “expose” in explaining
    the rule it adopted for calculating whether a business employs 10 or fewer
    employees (and therefore is not subject to the requirements of Proposition
    65). (1988 FSOR, supra, pp. 19, 26
     [as of
    Mar. 11, 2022].) The rule requires counting all full- and part-time employees
    “on the date on which the discharge, release or exposure occurs.” (Former
    Cal. Code Regs., tit. 22, § 12102; now tit. 27, § 25102, subd. (h).) Discussing
    the rule in the context of exposure to agricultural products, the agency
    rejected the assumption that exposure occurs on the date the product is
    consumed: “In fact, nothing provides that exposure occurs only at the time a
    particular consumer good is consumed. The term ‘expose’ generally means ‘to
    lay open,’ as to something which is injurious or dangerous. Laying an
    individual open to a chemical hazard through a consumer product could
    products and their packaging, such as manufacturers and packagers, to
    ensure such warnings are not placed where they may be overlooked by the
    consumer. It does not address the meaning of “expose” with respect to a
    business that sells a product to the consumer.
    58
    result from any act which propels the product toward the individual.” (1988
    FSOR, p. 19.)
    This interpretation makes clear that the original lead agency
    understood its definition of “expose” to refer to any act that brings the
    product containing a listed chemical into contact with an individual,
    regardless of the individual’s actual use. “Expose,” in other words, refers to
    potential exposure as well as realized exposure. The regulatory definition of
    “expose” has not changed in any meaningful way, and we are not aware of
    any departure from the lead agency’s original interpretation. That
    interpretation is consistent with the statutory requirement that Proposition
    65 warnings be provided before an individual is exposed to a listed chemical.
    (Health & Saf. Code, § 25249.6.) Necessarily, consumer product exposure
    warnings must be provided prior to or concurrent with sale to the retail
    consumer; once the product has reached the consumer, the seller,
    manufacturer or other party in the chain of distribution would have no means
    of providing a warning. The regulations’ safe harbor warning requirements
    for consumer products specify that the warning must be provided by one or
    more of four means, all of which entail visibility to the consumer prior to or
    during a purchase; 34 for Internet purchases, warnings must be provided prior
    to completion of the purchase. (Regs., § 25602, subds. (a) & (b).)
    34 These means are: “A product-specific warning provided on a posted
    sign, shelf tag, or shelf sign, for the consumer product at each point of display
    of the product”; “A product-specific warning provided via any electronic device
    or process that automatically provides the warning to the purchaser prior to
    or during the purchase of the consumer product, without requiring the
    purchaser to seek out the warning”; “A warning on the label that complies
    with the content requirements in Section 25603(a)”; and/or “A short-form
    warning on the label that complies with the content requirements in Section
    25603(b)” and is in a specified type size. (Regs., § 25602, subd. (a)(2)-(4).)
    59
    Interpreting “expose” by its ordinary meaning is also consistent with
    Proposition 65’s protective purpose. As we have said, the preamble to
    Proposition 65 expressly invoked the voters’ “rights” to “be informed about
    exposures to chemicals that cause cancer, birth defects, or other reproductive
    harm[,]” and to “secure strict enforcement of the laws controlling hazardous
    chemicals and deter actions that threaten public health and safety.” (Ballot
    Pamp., supra, p. 53.) Proposition 65 is not primarily about punishment for
    harm that has been inflicted; it is about protection from harmful chemicals,
    the ability to make informed choices about coming into contact with such
    chemicals, and deterrence of conduct that undermines these purposes. The
    interpretation of Health and Safety Code section 25249.6 advanced by
    Amazon and adopted by the trial court would absolve a business that
    knowingly and intentionally, without warnings, sold a product whose
    intended use would necessarily cause the consumer to ingest, inhale or
    otherwise come into bodily contact with a listed chemical, if the consumer
    happened not to use the product he or she purchased. This cannot be what
    the voters who enacted Proposition 65 intended.
    The trial court cited Consumer Cause v. Weider Nutrition Internat.
    (2001) 
    92 Cal.App.4th 363
    , 370, for its statement that “[former section]
    12201, subdivision (f) [now Cal. Code Regs., tit. 27, § 25102, subd. (i)] defines
    exposure in terms of a chemical . . . coming into contact with a person.”
    Consumer Cause did not consider whether selling or otherwise providing a
    product containing a listed chemical to a consumer constitutes exposing the
    consumer to the chemical. The issue in that case was whether the
    defendants exposed consumers to cancer-causing chemicals through products
    that did not contain any listed chemical but, when ingested, caused a
    chemical reaction in the body that increased natural levels of testosterone,
    60
    which can cause cancer. Holding the defendants’ products did not expose
    consumers to cancer-causing chemicals within the meaning of Proposition 65,
    the Consumer Cause court explained that “ ‘[t]he Act prohibits all means of
    directly bringing individuals into contact with chemicals known to the state
    to cause cancer . . .’ ” and the products at issue did not do so, since the
    increase in testosterone occurred only as a result of a reaction inside the
    body. (Consumer Cause, at p. 369.) The court further emphasized that ballot
    materials for Proposition 65 “focus[ed] on exposure to carcinogenic chemicals”
    and did not suggest Proposition 65 “was intended to apply when a person is
    exposed to a noncarcinogenic chemical which then causes a substance
    naturally occurring in the body to become carcinogenic.” (Consumer Cause,
    at p. 370.)
    Amazon argues that the need for evidence of “actual exposure” was
    particularly important in the present case because the total number of sales
    at issue was relatively small and there was a public health campaign to
    discourage use of skin-lightening creams, including a buy-back program that
    recovered some products before they were used. Aside from factual questions
    such as whether consumers who purchased the products at issue were aware
    of the public health notices or participated in the buy-back program, this
    argument begs the relevant question. The argument is premised on the
    assumption that Amazon cannot be said to have exposed a consumer to
    mercury in a skin-lightening cream unless and until the consumer has
    actually applied the cream to his or her skin. As we have explained, however,
    we understand “expose” as used in Health and Safety Code section 25249.6 as
    referring to potential as well as realized exposure from a product being used
    in the intended manner—“[l]aying an individual open to a chemical hazard”
    61
    by an “act which propels the product toward the individual.” (1988 FSOR,
    supra, p. 19.)
    Amazon certainly meets this definition. As described by the court in
    Bolger, supra, 53 Cal.App.5th at page 438, “Amazon placed itself between
    [the third-party seller and customer] in the chain of distribution of the
    product at issue here” by attracting customers to the Amazon Web site,
    providing product listings for the skin-lightening creams, receiving payment
    for the products, requiring communication between third-party sellers and
    customers to go through the Amazon Web site, demanding indemnification
    and fees for each purchase, and, for products using the FBA program,
    accepting possession of the product, storing it in an Amazon warehouse, and
    shipping it to the customer. “Whatever term we use to describe Amazon’s
    role, be it ‘retailer,’ ‘distributor,’ or merely ‘facilitator,’ it was pivotal in
    bringing the product here to the consumer.” (Ibid.)
    Finally, Amazon argues we should infer Lee attempted but was unable
    to discover any evidence of “actual exposure” from the fact that Lee obtained
    an order from the trial court compelling Amazon to provide contact
    information for purchasers of the products at issue, but did not present any
    evidence of actual use of the products. Lee’s motion to compel argued the
    contact information was “primarily relevant because it relates to Amazon’s
    defense that it should not be required to send warnings to purchasers ‘who
    have since used all the products,” 35 as Amazon had not offered any evidence
    35 When Lee sought a preliminary injunction, one of Amazon’s
    arguments in opposition was that “[i]f the injunction is entered, Amazon will
    be required to email purchasers of third-party products who have since used
    all the Products—informing them that products they used might have
    contained mercury . . . ,” which would not prevent further violations of
    Proposition 65, but “simply upset Amazon’s customers, over products Amazon
    didn’t even sell.” The trial court denied the request for this emailed notice.
    62
    that customers were no longer using the creams they purchased. Lee also
    argued the customer contact information would lead to discovery of percipient
    witnesses and material relevant to Amazon’s liability, with respect to both
    exposure and Amazon’s operations and knowledge. In granting the motion to
    compel, the trial court found Lee had “sufficiently shown that the contact
    information of consumers who purchased the skin creams may well lead to
    relevant and/or admissible information, including as to: (1) the nature of the
    transactions and Amazon’s role in them; (2) the extent to which a Proposition
    65 warning was available or known to the consumer; (3) the extent to which
    the consumers (or their family members) were exposed to the product; (4) the
    extent to which exposures continue; and (5) whether there was any
    communication with Amazon about the mercury or other content.” Amazon
    provided access to the customer contact information.
    Neither the record nor Lee’s briefs explain why he did not present
    evidence of individual consumers’ use of the skin-lightening products. But we
    see no reason to infer customers who purchased skin-lightening creams
    through the Amazon Web site did not use them. “Things happen according to
    the ordinary course of nature and the ordinary habits of life.” (Civ. Code,
    § 3546.) It is at least as likely Lee was unable to locate purchasers of the
    products willing to participate in this litigation, or decided not to pursue this
    source of potential evidence. Regardless, in light of our interpretation of
    Health and Safety Code section 25249.6, evidence of actual use was not
    necessary to establish the “expose” element of Lee’s claims. 36
    36We are not persuaded by Lee’s argument that the trial court
    precluded him from presenting the evidence of use it then found he failed to
    present. Lee points out that when his attorney asked Copan what evidence
    the CDPH found that skin-whitening cream was responsible for mercury
    contamination in homes, the trial court sustained Amazon’s objection that
    63
    IV.
    Lee contends the trial court erred in finding Amazon immune from
    liability for violating Proposition 65 under section 230 of the federal CDA.
    (§ 230(c)(1).) In relevant part, that section states, “No provider or user of an
    interactive computer service shall be treated as the publisher or speaker of
    any information provided by another information content provider.” (Ibid.)
    The statute expressly preempts state laws that are inconsistent with its
    terms: “Nothing in this section shall be construed to prevent any State from
    enforcing any State law that is consistent with this section. No cause of
    action may be brought and no liability may be imposed under any State or
    local law that is inconsistent with this section.” (§ 230(e)(3).)
    “ ‘Taken together, these provisions bar state-law plaintiffs from holding
    interactive computer service providers legally responsible for information
    created and developed by third parties. [Citation.] Congress thus
    established a general rule that providers of interactive computer services are
    liable only for speech that is properly attributable to them. [Citation.] State-
    these investigations had no connection to products sold through Amazon.
    Lee’s attorney stated that Amazon’s brief had “argued there was no way to
    prove exposure from people purchasing skin-lightening creams” and “[w]hile
    it may seem rather obvious, I feel we now need to prove that people who use
    products that they purchase, and Ms. Copan has personal knowledge of how
    people have used other skin-lightening creams.” The court responded, “I
    don’t think the Judge needs a witness on that. I’m going to have to make a
    decision as to the application of the regs and the statue, as to whether ‘ingest’
    means to physically ingest or whether it’s reasonably foreseeable a product
    will be used in the manner anticipated. . . . I don’t need Ms. Copan for that.
    [¶] As my father would say, that’s common sense. The issue is what the law
    is.” What the court precluded was testimony about how skin-lightening
    creams are used in general; what the court subsequently found lacking in
    Lee’s case was evidence that the specific products at issue in this case were in
    fact used by a consumer after being purchased through Amazon’s Web site.
    64
    law plaintiffs may hold liable the person who creates or develops unlawful
    content, but not the interactive computer service provider who merely
    enables that content to be posted online.’ (Nemet Chevrolet, Ltd. v.
    Consumeraffairs.com, Inc. (4th Cir. 2009) 
    591 F.3d 250
    , 254.)” (Bolger, supra,
    53 Cal.App.5th at p. 463.)
    “ “[S]ection 230(c)(1) precludes liability that treats a website as the
    publisher or speaker of information users provide on the website. In general,
    this section protects websites from liability for material posted on the website
    by someone else.” (Doe v. Internet Brands, Inc. (9th Cir. 2016) 
    824 F.3d 846
    ,
    850 (Internet Brands, Inc.).) “Immunity under section 230 extends to ‘ “(1) a
    provider or user of an interactive computer service (2) whom a plaintiff seeks
    to treat, under a state law cause of action, as a publisher or speaker (3) of
    information provided by another information content provider.” ’
    (HomeAway.com, Inc. v. City of Santa Monica (9th Cir. 2019) 
    918 F.3d 676
    ,
    681 (HomeAway.com).)” (Bolger, supra, 53 Cal.App.5th at p. 463.)
    “[P]ublication involves reviewing, editing, and deciding whether to publish or
    to withdraw from publication third-party content . . . . [A] publisher reviews
    material submitted for publication, perhaps edits it for style or technical
    fluency, and then decides whether to publish it.” (Barnes v. Yahoo!, Inc. (9th
    Cir. 2009) 
    570 F.3d 1096
    , 1102–1103 (Barnes).)
    The trial court concluded all the elements of CDA immunity were
    satisfied in the present case, finding Amazon is an interactive computer
    service provider, Lee’s claim is “predicated on information provided by
    another information content provider (i.e., the third-party sellers that
    provided the product descriptions without a Proposition 65 warning),” 37 and
    The trial court quoted Oberdorf v. Amazon.com Inc. (M.D.Pa. 2017)
    37
    
    295 F.Supp.3d 496
    , 501, a products liability case in which the district court
    65
    Lee “seeks to treat Amazon as the publisher or speaker of that information.”
    The trial court viewed Lee’s claims as seeking to impose liability on Amazon
    for “allowing third parties to list products for sale on its website without
    altering the disclosures and other content supplied by those third parties as
    to their own manufactured products.”
    Lee does not suggest Amazon is not an interactive computer service
    provider within the meaning of section 230, and does not dispute that the
    product descriptions for products sold on the Web site by third parties are
    provided by those parties. 38 He argues, however, that his claims are not
    precluded by section 230 because they do not seek to treat Amazon as the
    publisher or speaker of information provided by the third-party sellers, but
    stated, “ ‘Like an auctioneer, Amazon is merely a third-party vendor’s “means
    of marketing,” since third-party vendors—not Amazon—“cho[o]se the
    products and expose[]” them for sale by means of: the Marketplace.’ ” The
    same day the trial court entered judgment, Oberdorf was affirmed in part
    and vacated in part (Oberdorf v. Amazon.com Inc. (3d Cir. 2019) 
    930 F.3d 136
    , 153–154) in a decision which was then vacated when a petition for
    rehearing en banc was granted (Oberdorf v. Amazon.com Inc. (3d Cir. 2019)
    
    936 F.3d 182
    ). The Third Circuit has since certified for review by the
    Pennsylvania Supreme Court the question whether, under Pennsylvania law,
    an “e-commerce business, like Amazon” is strictly liable for a defective
    product in the circumstances of that case. (Oberdorf v. Amazon.com, Inc. (3d
    Cir. 2020) 
    818 Fed. Appx. 138
    , 143.)
    38 “Section 230 defines an ‘ “interactive computer service” ’ as ‘any
    information service, system, or access software provider that provides or
    enables computer access by multiple users to a computer server, including
    specifically a service or system that provides access to the Internet and such
    systems operated or services offered by libraries or educational institutions.’
    (§ 230(f)(2).) The term ‘ “information content provider,” ’ meanwhile, ‘means
    any person or entity that is responsible, in whole or in part, for the creation
    or development of information provided through the Internet or any other
    interactive computer service.’ (§ 230(f)(3).)” (Hassell, supra, 5 Cal.5th at
    p. 535.)
    66
    rather to hold Amazon accountable for violation of its own independent
    obligations under Proposition 65.
    “Congress enacted section 230 ‘for two basic policy reasons: to promote
    the free exchange of information and ideas over the Internet and to
    encourage voluntary monitoring for offensive or obscene material.’ ” (Hassell
    v. Bird (2018) 
    5 Cal.5th 522
    , 534 (Hassell), quoting Carafano v.
    Metrosplash.com, Inc. (9th Cir. 2003) 
    339 F.3d 1119
    , 1122.) The Ninth
    Circuit has explained: “As the heading to section 230(c) indicates, the
    purpose of that section is to provide ‘[p]rotection for “Good Samaritan”
    blocking and screening of offensive material.’ That means a website should
    be able to act as a ‘Good Samaritan’ to self-regulate offensive third party
    content without fear of liability.” (Internet Brands, Inc., supra, 824 F.3d at
    pp. 851–852.)
    Section 230 was enacted in part in reaction to an unpublished state
    court decision 39 holding that “an internet service provider became a
    ‘publisher’ of offensive content on its message boards because it deleted some
    offensive posts but not others.” (Internet Brands, Inc., supra, 824 F.3d at
    p. 852.) Under the state court’s reasoning “a website had to choose between
    voluntarily removing some offensive third party content, which would expose
    the site to liability for the content it did not remove, or filtering nothing,
    which would prevent liability for all third party content. [Citation.] ‘In
    passing section 230, Congress sought to spare interactive computer services
    this grim choice by allowing them to perform some editing on user-generated
    content without thereby becoming liable for all defamatory or otherwise
    unlawful messages that they didn’t edit or delete.’ ” (Ibid., quoting Fair
    39Stratton Oakmont, Inc. v. Prodigy Servs. Co., 
    1995 WL 323710
     (N.Y.
    Sup. Ct. May 24, 1995)
    67
    Hous. Council v. Roommates.Com, LLC (2008) 
    521 F.3d 1157
    , 1163
    (Roommates.Com).) “Simply put, the immunity provision was “ ‘enacted to
    protect websites against the evil of liability for failure to remove offensive
    content.’ ” (Internet Brands, Inc., at p. 852.)
    Congress intended section 230 “ ‘ “to promote the continued
    development of the Internet and other interactive computer services . . . [and]
    to preserve the vibrant and competitive free market that presently exists for
    the Internet and other interactive computer services, unfettered by Federal
    or State regulation.” [Citations.] To that end, CDA immunity is to be
    construed broadly, “to protect websites not merely from ultimate liability, but
    from having to fight costly and protracted legal battles. ” ’ (Cross v. Facebook,
    Inc. (2017) 
    14 Cal.App.5th 190
    , 206, 222.)” (Bolger, supra, 53 Cal.App.5th at
    p. 463.)
    Quoting Gentry v. eBay, Inc. (2002) 
    99 Cal.App.4th 816
    , 828 (Gentry),
    the trial court stated that section 230(c)(1) “preempts state law and ‘by its
    “plain language,” created a federal immunity to any cause of action that
    would make interactive service providers liable for any information
    originating with a third-party user of this service.’ ” In the trial court’s view,
    “all of the content at issue was provided by third-party sellers, not Amazon,”
    the third-party sellers did not provide Proposition 65 warnings and “[t]hus, if
    there is liability here, it is predicated entirely on the deficiencies in third-
    party content on Amazon’s online marketplace.” The trial court described
    Lee’s claim as seeking to “treat Amazon as the publisher or speaker” of
    “information provided by another information content provider (i.e., the
    third-party sellers that provided the product descriptions without a
    Proposition 65 warning)” and held it would be inconsistent with section
    230(c)(1) to impose liability on Amazon for “failing to include a warning on
    68
    products sold on its website by third parties, based on product content
    developed by those third parties without any encouragement, assistance or
    direction from Amazon, and without evidence that Amazon was aware of the
    chemical content of those products before allowing the third parties to list
    them on its website.” The court viewed Lee’s claims as based on Amazon
    “allowing third parties to list products for sale on its website without altering
    the disclosures and other content supplied by those third parties as to their
    own manufactured products.”
    Amazon views Gentry as “determinative precedent.” In that case,
    purchasers of what turned out to be forged autographed sports memorabilia
    alleged eBay violated Civil Code section 1739.7, which requires dealers of
    collectibles to furnish a certificate of authenticity to purchasers of
    autographed sports collectibles. (Gentry, supra, 99 Cal.App.4th at p. 820.)
    Although the plaintiffs argued they were attempting to enforce eBay’s
    independent duty to furnish a warranty under Civil Code section 1739.7, the
    Gentry court held section 230 barred the claims because imposing liability on
    eBay would hold it responsible, as publisher, for content originating with
    other parties, as it was the individual sellers who falsely identified the
    product as authentically autographed in order to sell it on eBay. (Gentry, at
    pp. 831–832.) Other causes of action were similarly barred because they
    sought to hold eBay responsible for having notice of illegal conduct by third
    parties and failing to take action such as withdrawing or altering the content
    provided by those parties that would amount to “exercise of a publisher’s
    traditional editorial functions.” (Id. at p. 835.)
    We do not see Gentry as dispositive of the issues in the present case.
    Lee does not suggest Amazon had any obligation to alter the content of the
    product descriptions provided by the third-party sellers or even to remove the
    69
    listings altogether. Instead, Lee maintains Amazon should have added its
    own Proposition 65 warning, pursuant to its independent obligation under
    Proposition 65, based on its conduct in providing a mercury-containing
    product to consumers. In Gentry, the plaintiffs’ argument that they were
    seeking to enforce eBay’s independent duty to provide the warranty of
    authenticity was unpersuasive because the statutory duty applied only to
    dealers in sports collectibles, and the plaintiffs’ “specific allegations reveal
    eBay is not in the business of selling or offering to sell the collectibles at
    issue; rather, it is the individual defendants who sold the items to plaintiffs,
    using eBay as a venue.” (Gentry, supra, 99 Cal.App.4th at p. 827.) Here,
    Proposition 65 imposes a duty to warn on every business that “exposes” an
    individual to a listed chemical. As we have said, Amazon did so by its
    “pivotal” role in “bringing the product here to the consumer.” (Bolger, supra,
    53 Cal.App.5th at p. 438; 1988 FSOR, p. 19 [“propel[ling] the product toward
    the individual”].) Lee’s claims are based on Amazon’s conduct in exposing
    consumers to mercury-containing products without providing Proposition 65
    warnings, not its failure to monitor, modify or remove third parties’ listings
    for the products, and thus do not require treating Amazon as speaker or
    publisher of third-party content. 40
    40  Like Gentry, other cases Amazon cites involved claims that
    necessarily based the defendants’ alleged liability on actions traditionally
    within a publisher’s role. In Cross v. Facebook, supra, 14 Cal.App.5th at
    pages 194 and 207, we held CDA immunity barred claims seeking to impose
    liability for Facebook’s failure to remove posts by users that allegedly incited
    violence and generated death threats against the plaintiffs. Chicago
    Lawyers’ Committee for Civil Rights Under Law, Inc. v. Craigslist, Inc. (7th
    Cir. 2008) 
    519 F.3d 666
    , 668, 672, held section 230 barred claims that
    Craigslist.com violated laws against housing discrimination by hosting user
    posts advertising, for example, “no minorities” or “no children.” Eberhart v.
    Amazon.com, Inc. (S.D.N.Y. 2018) 
    325 F.Supp.3d 393
    , 400, footnote. 5, which
    70
    Contrary to Amazon’s characterization, enforcing its obligations under
    Proposition 65 does not require it to “monitor, review, and revise” product
    listings. As both Lee and the Attorney General point out, the “knowingly and
    intentionally” requirement in Health and Safety Code section 25249.6 means
    Amazon is required to provide a warning where it has knowledge a product
    contains a listed chemical—for example, from public health alerts or direct
    notice. We recognize that any responsibility to provide warnings Amazon
    might have under section 25249.6 would not result in liability if the third-
    party seller of a skin-lightening product itself provided a Proposition 65
    warning, 41 and that Amazon would have to review the product’s packaging
    and/or listing on the Web site to determine whether a warning was provided
    by the third-party seller. These facts do not mean Lee’s claims necessarily
    treats Amazon as a speaker or publisher of information provided by the third-
    party sellers. If Amazon has actual or constructive knowledge that a product
    contains mercury, it might choose to review the product listing to determine
    held Amazon could not be held liable for injuries due to a defective product
    sold by a third-party seller, noted in passing that section 230 would bar any
    claim against Amazon “for the content it permitted [the seller] to post” on the
    Web site. La Park La Brea A LLC v. Airbnb, Inc. (C.D.Cal. 2017) 
    285 F.Supp.3d 1097
    , 1106, held section 230 barred a suit by the owner of
    apartments listed for rent on Airbnb.com in violation of the tenants’ lease
    prohibition against subletting. Doe v. Backpage.Com, LLC (1st Cir. 2016)
    
    817 F.3d 12
    , 22, applied section 230 immunity to claims that the Web site
    facilitated sex trafficking by enabling sex traffickers to advertise their
    victims for “escort” services. Daniel v. Armslist, LLC (Wis. 2019) 
    926 N.W.2d 710
    , held section 230 barred claims against a Web site that hosts ads by
    prospective sellers and purchasers of firearms for facilitating the illegal
    purchase of the weapon used in a mass shooting.
    41 Regulations section 25600.2, adopted in 2016, makes clear that the
    essential requirement is provision of a warning to the consumer, and
    expressly permits the parties in the chain of distribution to determine which
    one will be responsible for providing it.
    71
    whether the third-party seller had provided a Proposition 65 warning before
    providing the warning itself or removing the listing. But nothing inherently
    requires Amazon to do so. It could choose, instead, to act on its knowledge by
    providing the warning regardless, pursuant to its own obligations under
    Proposition 65.
    HomeAway.com provides an example, albeit in different factual
    circumstances. HomeAway and another company whose Web site similarly
    allows individuals seeking rental accommodations to connect with hosts
    offering such rentals, challenged a city ordinance prohibiting short-term
    home rentals except for licensed home-shares in which residents remain on
    site with guests. (HomeAway.com, supra, 918 F.3d at p. 679.) The plaintiffs
    argued the ordinance was preempted by section 230 because it required them
    to monitor and remove third-party content—listings not in compliance with
    the ordinance. (Id. at p. 682.) The court explained that while the plaintiffs
    might choose to monitor or remove listings, the ordinance did not require
    them to do so, only to cross-reference the city’s registry of licensed rentals
    before processing a requested booking. (Id. at pp. 682–683.)
    As our Supreme Court has observed, “not all legal duties owed by
    Internet intermediaries necessarily treat them as the publishers of third-
    party content, even when these obligations are in some way associated with
    their publication of this material. (See, e.g., Barnes, 
    supra,
     570 F.3d at
    p. 1107 [regarding § 230 immunity as inapplicable to a claim of promissory
    estoppel alleging that an Internet intermediary promised to remove offensive
    content].)” (Hassell, supra, 5 Cal.5th at pp. 542–543.) Similarly, the Ninth
    Circuit has said “[i]t is not enough that third-party content is involved” and
    has “rejected use of a ‘but-for’ test that would provide immunity under the
    CDA solely because a cause of action would not otherwise have accrued but
    72
    for the third-party content. [Citation.] We look instead to what the duty at
    issue actually requires[.]” (HomeAway.com, supra, 918 F.3d at p. 682.) “ ‘In
    evaluating whether a claim treats a provider as a publisher or speaker of
    user-generated content, “what matters is not the name of the cause of action”;
    instead, “what matters is whether the cause of action inherently requires the
    court to treat the defendant as the ‘publisher or speaker’ of content provided
    by another.” [Citation.] Put slightly differently, “courts must ask whether
    the duty that the plaintiff alleges the defendant violated derives from the
    defendant’s status or conduct as a ‘publisher or speaker.’ If it does, section
    230(c)(1) precludes liability.” ’ (Cross [v. Facebook], supra, 14 Cal.App.5th at
    p. 207.)” (Bolger, supra, 53 Cal.App.5th at p. 464.)
    Bolger, supra, 53 Cal.App.5th at page 439, a products liability case
    involving a defective computer battery purchased from a third-party seller on
    Amazon’s Web site, held section 230 did not shield Amazon from liability
    because the plaintiff’s strict liability claims “depend on Amazon’s own
    activities, not its status as a speaker or publisher of content provided by [the
    third-party seller] for its product listing.” The court first concluded that
    Amazon’s extensive role in third-party sales, especially where the seller
    utilizes the FBA program (as in Bolger and for at least one of the products
    here), supported application of strict liability, describing that role in terms
    consistent with the evidence in this case. (Bolger, at pp. 452–453; Loomis v.
    Amazon.com LLC (2021) 
    63 Cal.App.5th 466
     [agreeing with Bolger in case
    where seller did not use FBA].) 42 After discussing two cases from other
    42 The Bolger court noted that “Amazon created the environment (its
    website) that allowed [the third-party seller] to offer the replacement battery
    for sale”; “attracted customers through its own activities”; “set the terms of
    [the seller’s] involvement”; “demanded fees in exchange for [the seller’s]
    participation”; “required [the seller] to indemnify it”; “accepted possession of
    73
    jurisdictions that declined to apply section 230 immunity to strict liability
    claims, Bolger stated: “We agree with Erie [Ins. Co. v. Amazon.com Inc. (4th
    Cir. 2019) 
    925 F.3d 135
    ] and State Farm [Fire & Cas. Co. v. Amazon.com Inc.
    (W.D.Wis. 2019) 
    390 F.Supp.3d 964
    ] on this issue. Bolger’s strict products
    liability claims target Amazon’s role in ‘the vertical distribution of consumer
    goods’ (Bay Summit [Community Assn. v. Shell Oil Co. (1996)] 51 Cal.App.4th
    [762,] 773) as an ‘integral part of the overall producing and marketing
    enterprise’ for the [third-party seller’s] replacement laptop battery
    (Vandermark [v. Ford Motor Co. (1964)] 61 Cal.2d [256,] 262). It is based on
    Amazon’s own conduct, as described above, not the content of [the third-party
    seller’s] product listing. Bolger’s claims do not require a court to treat
    Amazon as the speaker or publisher of content provided by [the third-party
    seller]. The content of the product listing is not determinative, and it need
    not be attributed to Amazon to support strict liability. Instead, Amazon’s
    own involvement in the distribution of an allegedly defective product
    [the seller’s] products, registered them in its inventory system, and stored
    them in an Amazon warehouse awaiting sale”; “created the format for [the
    seller’s] offer for sale”; and “allowed [the seller] to use a fictitious name in its
    product listing.” (Bolger, supra, 53 Cal.App.5th at p. 452.) Additionally, the
    product listing “does not conspicuously inform the consumer of the identity of
    the third party seller or the nature of Amazon’s relationship to the sale”; the
    customer purchases the product by adding it to her Amazon cart and pays
    Amazon; under the FBA program, Amazon personnel retrieve the product
    from an Amazon warehouse and ship it to the customer in Amazon branded
    packaging (potentially together with items purchased from other sellers or
    Amazon itself); the seller is not involved in the sales transaction and “does
    not receive payment until Amazon chooses to remit the proceeds”; the
    customer sends returns to Amazon; and third-party sellers “are prohibited
    from communicating with Amazon customers except through the Amazon
    website, where such interactions are anonymized.” (Id. at pp. 452–453.)
    74
    supports strict liability for the reasons we have already discussed.” (Bolger,
    at p. 464.)
    Other cases similarly distinguish claims that treat an interactive
    computer service provider as a publisher from claims that do not, despite
    being associated with third-party content. In Barnes, 
    supra,
     
    570 F.3d 1096
    ,
    after a period of failing to respond to the plaintiff’s requests to remove
    indecent material her former boyfriend posted without her consent on
    Yahoo.com, the company expressly promised to remove the material, then did
    not do so. (Id. at pp. 1098–1099.) The Ninth Circuit concluded the plaintiff’s
    cause of action for “negligent undertaking” was barred by section 230 because
    it sought to hold Yahoo liable for failing to remove the offending material,
    which was publishing activity.
    The plaintiff’s cause of action for promissory estoppel, however, was not
    barred. (Barnes, supra, 570 F.3d at p. 1109.) Although the promise
    underlying this claim involved the same conduct—removing the material
    from the Web site—the duty allegedly violated “springs from a contract—an
    enforceable promise—not from any non-contractual conduct or capacity of the
    defendant.” “Contract liability here would come not from Yahoo’s publishing
    conduct, but from Yahoo’s manifest intention to be legally obligated to do
    something, which happens to be removal of material from publication.” (Id.
    at p. 1107.) The “outwardly manifested intention to create an expectation on
    the part of another . . . generates a legal duty distinct from the conduct at
    hand, be it the conduct of a publisher, of a doctor, or of an overzealous uncle.”
    (Id. at p. 1108.)
    Internet Brands, Inc., supra, 
    824 F.3d 846
     provides another illustration
    of the same point. There, two individuals used the defendant’s Web site, a
    networking Web site for the modeling industry, to lure the plaintiff to sham
    75
    auditions where she was drugged and raped. (Id. at p. 848.) The plaintiff
    alleged that the Web site owner had independent knowledge of the ongoing
    scheme but failed to warn her or other Web site users, in violation of a duty
    to warn imposed by California law, and the district court dismissed the action
    as barred by section 230. (Internet Brands, Inc., at pp. 848–850.) Reversing,
    the Ninth Circuit explained that the plaintiff did not seek to hold the Web
    site owner liable as publisher or speaker of a third party’s posted content, for
    failing to remove such content or for any conduct related to monitoring or
    failing to monitor posts on the Web site. (Id. at p. 851.) Instead, the plaintiff
    argued the defendant was liable for failure to warn her about information
    obtained from an outside source about the scheme being perpetrated on its
    Web site, which could be accomplished without altering or removing the
    third-party content, for example, by posting a warning on the Web site or
    emailing users. (Ibid.) Accordingly, the negligent failure to warn claim did
    not seek to hold the Web site owner liable as the “ ‘publisher or speaker of
    any information provided by another information content provider’ ” and
    section 230 did not bar the claim. (Internet Brands, Inc., at p. 851.)
    Here, Lee claims Amazon violated Proposition 65 exposing consumers
    to mercury without warnings through its own conduct. The claims do not
    attempt to hold Amazon responsible for third-party sellers’ content (except in
    the sense that Amazon would have been able to disclaim responsibility for
    providing warnings if the sellers had provided them). As we have discussed,
    the claims do not require Amazon to modify or remove third-party content
    but rather to provide a warning where Amazon’s own conduct makes it
    subject to Health and Safety Code section 25249.6.
    The Ninth Circuit cases make another point that is of critical
    importance here. HomeAway.com emphasized that “[l]ike their brick-and-
    76
    mortar counterparts, internet companies must also comply with any number
    of local regulations concerning, for example, employment, tax, or zoning” and
    “allowing internet companies to claim CDA immunity under these
    circumstances would risk exempting them from most local regulations
    and . . . ‘create a lawless no-man’s-land on the Internet.’ ” (HomeAway.com,
    supra, 918 F.3d at p. 683, quoting Roommates.com, supra, 521 F.3d at
    p. 1164.) The court explained, “We have consistently eschewed an expansive
    reading of [section 230] that would render unlawful conduct ‘magically . . .
    lawful when [conducted] online,’ and therefore ‘giv[ing] online businesses an
    unfair advantage over their real-world counterparts.’ ” (HomeAway, at
    p. 683, quoting Roommates.com, at p. 1164.) In this respect, “ ‘we must be
    careful not to exceed the scope of the immunity provided by Congress.’ ”
    (Internet Brands, Inc., supra, 824 F.3d at p. 853, quoting Roommate.com, at
    p. 1164, fn. 15.)
    If a skin-lightening cream is sold in a brick-and-mortar drug store that
    was aware the product contained mercury, there is no question that retail
    seller would have some obligation to provide Proposition 65 warnings—
    depending, of course, on whether entities further up the distribution chain
    had provided warnings for the products and, if not, could be held to account.
    Nothing in the text or purposes of the CDA suggests it should be interpreted
    to insulate Amazon from responsibilities under Proposition 65 that would
    apply to a brick-and-mortar purveyor of the same product.
    Not only would such an interpretation give Amazon a competitive
    advantage unintended by Congress in enacting the CDA, but it would be
    inimical to the purposes of Proposition 65. Amazon makes it possible for
    sellers who might not be able to place their products in traditional retail
    stores to reach a vast audience of potential customers. (E.g., Bolger, supra,
    77
    53 Cal.App.5th at p. 453 [“The Amazon website . . . enables manufacturers
    and sellers who have little presence in the United States to sell products to
    customers here”].) The evidence in this case indicates that mercury-
    containing skin-lightening products are overwhelmingly likely to have been
    manufactured outside the United States—unsurprisingly, as FDA
    regulations prohibit use of mercury as a skin-lightening agent in cosmetics.
    (
    21 C.F.R. § 700.13
    .) This makes it all the more likely Amazon may be the
    only business that can readily be compelled to provide a Proposition 65
    warning for these products. (See 2016 FSOR, supra, p. 55 [discussing
    impracticality of enforcing warning requirement against foreign entity
    without agent for service of process in United States]; Bolger, supra,
    53 Cal.App.5th at p. 453 [noting as first factor supporting application of strict
    liability doctrine to Amazon that it “may be the only member of the
    distribution chain reasonably available to an injured plaintiff who purchases
    a product on its website”].) Amazon is thus making available to consumers,
    and profiting from sales of, products that clearly require Proposition 65
    warnings, yet are likely to have been manufactured and distributed by
    entities beyond the reach of reasonable enforcement efforts. Insulating
    Amazon from liability for its own Proposition 65 obligations in these
    circumstances would be anomalous.
    Proposition 65, as we have said, “ ‘is a remedial law, designed to protect
    the public’ ” which must be construed “ ‘broadly to accomplish that protective
    purpose.’ ” (Center for Self-Improvement & Community Development v.
    Lennar Corp., 
    supra,
     173 Cal.App.4th at pp. 1550–1551, quoting People ex rel.
    Lungren v. Superior Court, 
    supra,
     14 Cal.4th at p. 314.) Moreover, states’
    “police powers to protect the health and safety of their citizens . . . are
    ‘primarily, and historically, . . . matter[s] of local concern.’ ” (Medtronic, Inc.
    78
    v. Lohr (1996) 
    518 U.S. 470
    , 485.) The United States Supreme Court has
    explained that “[w]hen addressing questions of express or implied pre-
    emption, we begin our analysis ‘with the assumption that the historic police
    powers of the States [are] not to be superseded by the Federal Act unless that
    was the clear and manifest purpose of Congress.’ [Citation].” (Altria Group,
    Inc. v. Good (2008) 
    555 U.S. 70
    , 77.) The “strong presumption against
    displacement of state law . . . applies not only to the existence, but also to the
    extent, of federal preemption. [Citation.] Because of it, ‘courts should
    narrowly interpret the scope of Congress’s “intended invalidation of state
    law” whenever possible.’ [Citation].” (Brown v. Mortensen (2011) 
    51 Cal.4th 1052
    , 1064.)
    As the Ninth Circuit has explained, Congress intended “to preserve the
    free-flowing nature of Internet speech and commerce without unduly
    prejudicing the enforcement of other important state and federal laws. When
    Congress passed section 230 it didn’t intend to prevent the enforcement of all
    laws online; rather, it sought to encourage interactive computer services that
    provide users neutral tools to post content online to police that content
    without fear that through their ‘good samaritan . . . screening of offensive
    material,’ [citation], they would become liable for every single message posted
    by third parties on their website.” (Roommates.com, supra, 521 F.3d at
    p. 1175, quoting § 230(c).)
    The text of section 230(e)(3) is clear that state laws inconsistent with
    section 230 are preempted while those consistent with section 230 are not
    preempted. Proposition 65’s warning requirement is an exercise of state
    authority to protect the public that imposes obligations on any individual who
    exposes another to a listed chemical. Proposition 65 is not inconsistent with
    the CDA because imposing liability on Amazon for failing to comply with its
    79
    own, independent obligations under Proposition 65, does not require treating
    Amazon as the publisher or speaker of third-party sellers’ content.
    Accordingly, if Lee can establish all the elements of a violation of Proposition
    65, section 230 does not immunize Amazon from liability.
    DISPOSITION
    The judgment is reversed and the matter is remanded for further
    proceedings in accordance with the views expressed in this opinion.
    On remand, if Lee is able to establish all the elements of his claims as
    to the products purchased from Amazon and tested for mercury content, the
    trial court shall determine whether the products with different ASINs
    identified in Lee’s pretrial brief as among the 11 products at issue were in
    fact the same products as the ones for which samples were tested, and shall
    determine penalties in accordance with Health and Safety Code section
    25249.7 for any violations of Proposition 65 established.
    80
    _________________________
    Kline, J.*
    We concur:
    _________________________
    Richman, Acting P.J.
    _________________________
    Stewart, J.
    Lee v. Amazon (A158275)
    *Assigned by the Chief Justice pursuant to article VI, section 6 of the
    California Constitution.
    81
    Trial Court:                                Alameda County Superior Court
    Trial Judge:                                Hon. Robert McGuiness
    Attorney for Plaintiff and Appellant        Law Office of Jonathan Weissglass
    Larry Lee:                                  Jonathan Weissglass
    Greenfire Law
    Rachel S. Doughty
    Jessica L. Blome
    Attorneys for Amicus Curiae on behalf       Rob Bonta
    of Plaintiff and Appellant:                 Attorney General of California
    Dennis A. Ragen
    Roxanne Carter
    Deputy Attorneys General
    Attorneys for Amicus Curiae                 Danielle R. Fugere
    As you Sow on behalf of Plaintiff           Chelsea J. Linsley
    Appellant:
    Attorneys for Amicus Curiae                 Altshuler Berzon
    Center For Food Safety on behalf            Barbara J. Chisholm
    of Plaintiff and Appellant:                 P. Casey Pitts
    Attorneys for Amici Curiae Black            Environmental Law Clinic
    Women for Wellness and the Mercury          Mills Legal Clinic at Stanford Law School
    Policy Project/Tides Center on behalf       Deborah A. Sivas
    of Plaintiff and Appellant:                 Molly Loughney Melius
    Attorneys for Defendant                     Doll Amir & Eley
    and Respondent Amazon.com, Inc.:            Gregory L. Doll
    Brett H. Oberst
    Jamie O. Kendall
    Lloyd Vu
    Attorneys for Amicus Curiae                 Law Office of Fred. J. Hiestand
    The Civil Justice Association of            Fred J. Hiestand
    California on behalf of Defendant
    and Respondent:
    82