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March 26, 2026 Get Citation Alerts Download PDF Add Note

Earl Parris, Jr. v. 3M Company, et al.

District Court, N.D. Georgia

• Citations: None known
• Docket Number: 4:21-cv-00040

• Precedential Status: Unknown Status

• Opinion

• Authorities (13)

• Cited By (0)

• Summaries (0)

• Similar Cases (612)

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Trial Court Document

IN THE UNITED STATES DISTRICT COURT

FOR THE NORTHERN DISTRICT OF GEORGIA

ROME DIVISION

EARL PARRIS, JR.

Individually, and on behalf of a Class of

persons similarly situated,

 Plaintiff,                                                       

      v.                     CIVIL ACTION FILE                    
                             NO. 4:21-CV-40-TWT                   

3M COMPANY, et al.,

 Defendants.                                                      

               OPINION AND ORDER                                  

This is an action under the Clean Water Act. It is before the Court on
Defendant 3M Company’s (“3M”) Motion to Exclude the Expert Testimony of
Erica DiFilippo [Doc. 872], Defendant Daikin America, Inc. (“Daikin”), E.I.
DuPont de Nemours and Company (“DuPont”), and The Chemours Company’s

(“Chemours”) Motion to Exclude the Expert Testimony of Erica DiFilippo1
[Doc. 894]. For the following reasons, the Court DENIES Defendant 3M’s
Motion to Exclude the Expert Testimony of Erica DiFilippo [Doc. 872] and
GRANTS in part and DENIES in part Defendant Daikin, DuPont, and
Chemours’s Motion to Exclude the Expert Testimony of Erica DiFilippo

1 Upon motion, the Court authorized DuPont and Chemours to join

Daikin’s Motion to Exclude the Expert Testimony of Erica DiFilippo. (

Order, Mar. 2, 2026, [Doc. 1074].) The Court will nonetheless refer
to that Motion as “Defendant Daikin’s Motion to Exclude DiFilippo” to easily
distinguish it from “Defendant 3M’s Motion to Exclude DiFilippo.”

[Doc. 894].

I. Background

This case arises out of the contamination of surface waters and drinking

water in Chattooga County, Georgia, with per- and polyfluoroalkyl substances
known as “PFAS.” (2d Am. Compl. ¶ 1 [Doc. 280].) The facts of this case are
well known to the parties by this point, so the Court will not belabor them here.
In essence, Plaintiff Earl Parris, Jr., alleges that the Defendants have
contaminated his city’s water supply and thus his household water with PFAS.
Parris is a resident of Summerville, Georgia, who receives running, potable

water to his home from the Summerville Public Works and Utilities
Department. ( ¶ 21.) The City of Summerville, which has intervened in this
case, uses Raccoon Creek as the main source of its municipal water supply.
( ) The Defendants are the following companies, which allegedly
manufactured and supplied the PFAS discharged into Raccoon Creek: 3M

Company (“3M”), Daikin America, Inc., E.I. du Pont de Nemours and Company,
and The Chemours Company. At present, the Defendants move to exclude the

testimony of expert witness Erica DiFilippo.

II. Legal Standard

Federal Rule of Evidence 702 governs the admissibility of expert
testimony. Under that rule, “expert testimony is admissible if (1) the expert is
qualified to testify regarding the subject of the testimony; (2) the expert’s

                        2                                         

methodology is sufficiently reliable as determined by the sort of inquiry
mandated in ; and (3) the expert’s testimony will assist the trier of fact
in understanding the evidence or determining a fact at issue.”

                   , [766 F.3d 1296, 1304](https://www.courtlistener.com/opinion/2732053/marianne-chapman-v-the-procter-gamble-distributing-llc/#1304) (11th Cir. 2014) (citation 

modified). Courts perform a “gatekeeping role” in excluding expert testimony
that does not satisfy these qualification, reliability, and helpfulness
requirements. , 509 U.S. 579, 597 (1993).

“This gatekeeping role, however, is not intended to supplant the adversary
system or the role of the jury” in determining the persuasiveness of an expert’s

testimony. , 730 F.3d 1278, 1282 (11th Cir.

2013) (citation modified). Rather, the goal is to “make certain that an expert
. . . employs in the courtroom the same level of intellectual rigor that
characterizes the practice of an expert in the relevant field.”

, 387 F.3d 1244, 1260 (11th Cir. 2004) (en banc) (quoting

, 526 U.S. 137, 152 (1999)). “The proponent of the expert
testimony always bears the burden” of establishing qualification, reliability,

and helpfulness. (citation modified).

A. Qualifications

Rule 702 provides that a witness may be “qualified as an expert by
knowledge, skill, experience, training, or education.” Fed. R. Evid. 702. When
assessing a witness’s qualifications, the district court must focus on “the

                        3                                         

matter to which the expert seeks to testify—i.e., ‘to the task at hand.’”
, 995 F.3d 839, 854 (11th Cir. 2021) (quoting , 509 U.S. at 597). While a witness may be “well-trained, highly educated, and

experienced” with an “impressive professional track record,” Rule 702
contemplates “a more thorough analysis of whether [the witness] is qualified
and competent to testify as an expert

.” , 239 F. Supp. 2d 1308, 1315–16 (N.D.

Ga. 2002) (emphasis added). “It is for that reason that ‘expertise in one field
does not qualify a witness to testify about others.’” , 995 F.3d at 854 (quoting , 772 F.3d 1352, 1368 (11th Cir. 2014)). The question whether a proposed witness is qualified to
testify as an expert rests within the district court’s discretion. , 239 F.
Supp. 2dat 1314 (citing , 528 F.2d 987,

990 (5th Cir. 1976)).

B. Reliability

In determining whether an expert witness’s testimony is reliable under

Rule 702, the Court must evaluate “whether the reasoning or methodology
underlying the testimony is scientifically valid and . . . whether that reasoning
or methodology properly can be applied to the facts in issue.” , 509 U.S.
at 592–93. sets forth a number of factors relevant to this inquiry,
including (1) whether an expert’s theory or technique can be tested;

                        4                                         

(2) whether the theory or technique has been subjected to peer review and
publication; (3) the known or potential rate of error of a scientific technique;
and (4) whether a known technique has achieved widespread acceptance in the

scientific community. at 593–94. These factors are not intended to be a
“definitive checklist,” at 593; rather, “the law grants the trial judge broad
latitude to determine . . . whether ’s specific factors are, or are not,
reasonable measures of reliability in a particular case.” , 526 U.S. at 153.

Ultimately, the district court’s objective under is to “make

certain that an expert . . . employs in the courtroom the same level of
intellectual rigor that characterizes the practice of an expert in the relevant
field.” , 526 U.S. at 152. To this end, a district court may not admit
opinions that “[are] connected to existing data only by the of the

expert” or leave “too great an analytical gap between the data and the opinion
proffered.” , 522 U.S. 136, 146 (1997).

C. Helpfulness

An expert’s opinions must be helpful to a trier of fact. Fed. R.
Evid. 702(a). The helpfulness of an expert’s opinions to a trier of fact speaks
“primarily to relevance,” which is a “liberal” standard.

, 813 F.3d 983, 988 (11th Cir. 2016) (citations omitted). “Expert
testimony which does not relate to any issue in the case is not relevant and,

                        5                                         

ergo, non-helpful.” , 509 U.S. at 591 (citation omitted). Even if the
testimony is relevant, however, it must “concern[ ] matters that are beyond the
understanding of the average lay person.” , 387 F.3d at 1262. Expert

testimony “generally will not help the trier of fact when it offers nothing more
than what lawyers for the parties can argue in closing arguments.” at 1262–
63.

III. Discussion

Erica DiFilippo holds a Ph.D. in hydrology and water resources and
“ha[s] over fifteen years of experience addressing the fate and transport of

organic and inorganic chemicals in the environment.” (Def. 3M’s Mot. to
Exclude DiFilippo, Ex. A (“DiFilippo Report”),2 at 8 [Doc. 900-2].) She “ha[s]
conducted numerous studies of groundwater transport, statistical geochemical
analysis, . . . and fate and transport of PFAS.” ( ) As a member of the
Interstate Technology Regulatory Council’s PFAS team and the National
Groundwater Association’s PFAS working group, she has studied the physical
and chemical properties of PFAS and PFAS forensic techniques. ( )

DiFilippo’s report offers seven opinions3 related to the use of PFAS in the
textile mill operated by Mount Vernon Mills (“MVM”) in Trion, Georgia, the
transport and fate of the PFAS from the mill to Raccoon Creek, and the studies

2 The pagination of this exhibit reflects the PDF pagination.

3 DiFilippo’s report technically lists eleven opinions, but Opinions 8–11
appear to be duplicates of Opinions 2–3, 6–7. ( DiFilippo Report, at 10–11.)
6

the Defendants conducted demonstrating their knowledge of these events. (

at 10.)

A. Degradation Time and Pathways

According to DiFilippo, MVM used “side-chain fluorinated polymers” in
its textile manufacturing, which “degrade with half-lives between 10 to 100
years and produce PFOS and PFOA.”4 (DiFilippo Report, at 24, 31–32.) In
other words, it takes 10 to 100 years for half of these polymer products to
degrade into PFOS and PFOA, which are types of PFAS. ( Def. Daikin’s

Mot. to Exclude DiFilippo, at 2 [Doc. 895-1].) With respect to 3M’s “Scotchgard

FC-248” product in particular, DiFilippo further opines that it will degrade
over “decades,” first into components such as n-MeFOSAA and then finally into
PFOS. ( Def. 3M’s Mot. to Exclude DiFilippo, Ex. E (“3M’s 2025 DiFilippo
Dep. Excerpts”), at 206:4–25 [Doc. 872-6]; DiFilippo Report, at 22, 50.)
The Defendants challenge the degradation time offered by DiFilippo as
unreliable and unsupported. (Def. Daikin’s Mot. to Exclude DiFilippo, at 2; Def.
3M’s Mot. to Exclude DiFilippo, at 4 [Doc. 900-1].) They point out that

DiFilippo herself acknowledged that degradation time depends on a variety of
factors (e.g., pH, temperature, soil composition, polymer chemistry) yet she did
not consider any of those factors with respect to the Defendants’ specific

4 PFOS is short for perfluorooctanesulfonic acid, and PFOA is short for
perfluorooctanoic acid.

7

products and Raccoon Creek. (Def. Daikin’s Mot. to Exclude DiFilippo, at 3–5;
Def. 3M’s Mot. to Exclude DiFilippo, at 4–6.) Additionally, 3M takes issue with
the degradation pathway DiFilippo theorizes for Scotchgard FC-248, arguing

that it is contravened by the absence of N-MeFOSAA in any existing surface
water samples. (Def. 3M’s Mot. to Exclude DiFilippo, at 6–13.)

The Court disagrees with the Defendants. The degradation time
identified in DiFilippo’s report is based on a reliable methodology and
supported by sufficient facts. DiFilippo analyzed a plethora of peer-reviewed
studies on the degradation of side-chain fluorinated polymers, including their

degradation in biosolids and under a variety of conditions. (DiFilippo Report,
at 24–30.) She also specifically reviewed studies of 8:2 fluorotelomer alcohol
(8:2 FTOH) and n-methyl perfluorooctane sulfonamido ethylacrylate

(n-MeFOSEA), which she opines are directly relevant to the chemicals
produced by Daikin and 3M, respectively. ( at 22–30.) From these studies,
DiFilippo found that “the majority of estimates place the half-life around
100 years,” before going on to estimate a half-life of 10 to 100 years for the

side-chain fluorinated polymers at issue here. ( at 31–32.) The Defendants
do not challenge the findings of these studies.

The Defendants instead fault DiFilippo for not testing the specific
environmental conditions in Raccoon Creek, but they have not shown that her
failure to do so is contrary to standard industry practice or otherwise renders

                        8                                         

her opinions unreliable. , 526 U.S. at 152 (emphasizing ’s

goal of ensuring “that an expert . . . employs in the courtroom the same level
of intellectual rigor that characterizes the practice of an expert in the relevant

field”). DiFilippo explains that her reliance on experiments using modeling and
batch studies is “common practice” in the environmental fate-and-transport
field and “one of the most effective ways with which to evaluate the
degradation of contaminants in environmental media.” ( Def. Daikin’s Mot.
to Exclude DiFilippo, Ex. 11 (“DiFilippo Rebuttal Report”), 5 at 10
[Doc. 895-11].) Moreover, DiFilippo did verify these laboratory studies against

relevant field data from Raccoon Creek. (DiFilippo Rebuttal Report, at 28;
DiFilippo Report, at 32 (citing four years of Raccoon Creek samples
showing PFOS and PFOA concentrations).) She states that the “continued

presence of n-MeFOSE [the “initial metabolite” of FC-248] empirically
supports the long half-lives for side-chain fluoropolymer degradation found in
laboratory studies,” since FC-248 “was last used at [Mount Vernon Mills] in
2000.” ( at 28) She says the same about the continued presence of 8:2 FTOH,

which is derived from long-chain fluorotelomer polymers last used at MVM in
2016. ( ) DiFilippo further concludes:

[W]hile laboratory studies have identified several factors that

play important roles in the degradation of side-chain

fluoropolymers, a detailed evaluation of every factor (e.g., pH,

photolysis, microbial community) is not needed. The data

5 The pagination of this PDF reflects the PDF pagination.

9

collected from both the biosolids and the agricultural fields
demonstrate on their own that degradation of the side-chain
fluoropolymers used at Mount Vernon Mills is occurring and that

degradation occurs on the scale of decades not months or years.

( at 29.) The Court therefore finds DiFilippo’s methodology for estimating
degradation time reliable for purposes.

The Court finds DiFilippo’s testimony on the degradation pathway for
3M’s Scotchgard FC-248 product reliable as well. Several of 3M’s own studies
were among the degradation studies that DeFilippo reviewed. ( DiFilippo
Report, at 20, 24–26, 29–30.) For example, one 3M study concluded that the
half-life of a 3M formulation similar to FC-248 was ninety-one years,6 ( at
25). DiFilippo opines that one step in this long process is FC-248’s degradation
into n-MeFOSAA. (3M’s 2025 DiFilippo Dep. Excerpts, at 206:4–25; DiFilippo
Report, at 22, 50.) While 3M harps on the fact that in

Raccoon Creek have not detected any n-MeFOSAA, DiFilippo’s report is
supported by from Trion’s wastewater treatment plant
showing concentrations of n-MeFOSAA and PFOS. (DiFilippo Report, at 22.)
That is sufficient to bridge the analytical gap.

To point out that n-MeFOSAA should have been detected in the water
samples, the Defendants point to testimony from one of the Plaintiffs’ experts

6 The 3M study evaluated FC-845 rather than FC-248, but DiFilippo

noted that FC-845 and FC-248 are “both n-MeFOSEA copolymers with similar
weight percents of active fluorochemicals and PFOS-equivalents,” making the
degradation of both “likely similar.” (DiFilippo Report, at 25.)

10

and the presence of n-MeFOSAA in wastewater at the Trion plant. (Def. 3M’s
Mot. to Exclude DiFilippo, at 7–8; Reply Br. in Supp. of Def. 3M’s Mot. to
Exclude DiFilippo, at 6–7 [Doc. 1019-1].) But there are at least two problems

here. First, the testimony that 3M cites from the Plaintiffs’ expert, Charlie
Andrews, does not state that n-MeFOSAA can be detected in surface water
samples, let alone that it should be or that it is likely to be. He simply testified
that it “could” be the case that “some of the undegraded side-chain
fluoropolymers erode with soil particles into the creeks in heavy rain.” (Def.
3M’s Mot. to Exclude DiFilippo, Ex. F, at 107:2–5 [Doc. 900-4];

103:9–107:19 (providing additional context).) Moreover, in response to the next
question, Andrews testified that those same polymers do not easily dissolve in
surface water. ( at 107:6–13.) The Court is no expert on this subject, but the
Plaintiffs suggest this means it is more difficult to detect in surface water
samples, which lessens the weight of the Defendants’ contention. (Pls.’ Resp.
Br. in Opp’n to Def. 3M’s Mot. to Exclude DiFilippo, at 16 [Doc. 928].) Second,
regarding wastewater samples that did detect n-MeFOSAA, the Defendants

are free to argue on cross-examination the significance of that data in relation
to DiFilippo’s testimony.7 The Court is not persuaded that the existence of
such data creates untenable gaps in DiFilippo’s reasoning or methodology. For

7 The same can be said about 3M’s other arguments that certain soil
samples did not detect n-MeFOSAA. (Def. 3M’s Mot. to Exclude, at 11–12.)
11

all these reasons, the Court denies the Defendants’ Motion to Exclude
DiFilippo’s opinions on degradation time and pathways.

B. PFOS and PFOA Equivalents

DiFilippo opines that “[t]he amount of PFOS or PFOA present in a

textile product . . . can be expressed in terms of PFOS or PFOA-equivalents.”
(DiFilippo Report, at 15.) She testified that the equivalents are “a way to
determine in a worst-case scenario . . . how much PFOA or PFOS” would be
produced by the Defendants’ products. (Def. Daikin’s Mot. to Exclude, Ex. 2
(“Daikin’s DiFilippo Dep. Excerpts”), at 48:21–25 [Doc. 895-3].) For example,

DiFilippo calculates that one pound of Scotchgard FC-248 contains 0.12 pounds
of PFOS, which is equivalent to approximately 12% of Scotchgard FC-248’s
total mass. ( ) She performs a similar calculation to find that approximately
11% of Daikin’s TG-470 product is PFOA. ( ) To calculate these equivalents,
DiFilippo identified the molecular weight of the “PFAS precursors” present in
the Defendants’ products and the total mass of the products, then assumed
that the full weight of the PFAS precursors would degrade into “terminal

PFAS” such as PFOS or PFOA. ( ) “PFAS precursors” are polyfluoroalkyl

substances that further degrade into perfluoroalkyl substances such as PFOS
and PFOA, which generally do not degrade further and are thus “often referred
to as terminal PFAS.” (DiFilippo Report, at 12.)

                       12                                         

The Defendants contend that the methodology behind these PFOS and

PFOA equivalents is unreliable for two primary reasons. 8 First, the
Defendants argue that her calculations are inaccurate. (Def. Daikin’s Mot. to

Exclude DiFilippo, at 6–8, 10–11; Def. 3M’s Mot. to Exclude DiFilippo, at 14–
15.) They cite DiFilippo’s deposition testimony in which she admits that, while
her report assumes 100% of the PFAS precursors would degrade into terminal
PFAS, the percentage that would degrade into terminal PFAS under realistic
environmental conditions would be less than 100%. (Daikin’s DiFilippo Dep.
Excerpts, at 244:13–21.)

Second, the Defendants cite DiFilippo’s testimony to show that her
equivalency methodology is not an accepted or peer-reviewed methodology
within the scientific community. (Def. Daikin’s Mot. to Exclude DiFilippo, at
8–10; Def. 3M’s Mot. to Exclude DiFilippo, at 14.) When DiFilippo was asked
whether her equivalency methodology was accepted in the scientific
community, the Defendants pointed out that she could not identify any EPA or
state regulatory documents that used the methodology. (Daikin’s DiFilippo

Dep. Excerpts, at 50:20–51:6.) Rather, she responded that she had seen the
same methodology “used in documents by [an organization known as] Battelle”

8 Both Daikin’s and 3M’s briefs advance the same general arguments,
but Daikin focuses on PFOA equivalents while 3M focuses on PFOS
equivalents. ( Def. Daikin’s Mot. to Exclude DiFilippo, at 6–11,

Def. 3M’s Mot. to Exclude DiFilippo, at 14–15.)

13

and “in reference to [Aqueous Film Forming Foam] formulations.” ( at
49:10–21.)

The Court declines to exclude DiFilippo’s opinions on PFOS and PFOA

equivalents. Regarding the potential inaccuracy of these equivalents, DiFilippo
acknowledges that the equivalents are a “worst case” calculation that assumes
100% of the PFAS precursors degrade into terminal PFAS. (Daikin’s DiFilippo
Dep. Excerpts, at 48:21–25.) She acknowledges this limitation and does not
opine that these “worst case” calculations are certain to transpire. Thus, this
limitation is not an appropriate justification for exclusion. And that is

especially so given that DiFilippo has testified about the high percentage of
PFAS precursors that become PFOS and PFOA, respectively. For example, she
cites one set of studies in which the “vast majority” of PFAS precursors
degraded into PFOS and another where the “overwhelming majority” of PFAS
precursors degraded into PFOA. (DiFilippo Rebuttal Report, at 22–23;

Daikin’s DiFilippo Dep. Excerpts, at 244:13–21 (testifying that the percentage
under realistic environmental conditions still remains as high as “90 percent

or so” for PFOA); at 95:11–96:7 (testifying that “95 percent or more . . . of
the degradation of 8:2 FTOH will result in the formation of PFOA”).) The Court
is not persuaded that the error rate is so high that DiFilippo’s methodology is
unreliable. , 603 F. Supp. 3d 1259, 1281 (S.D. Fla. 2022)
(“[A]n expert’s method need not be perfect, nor must he apply it perfectly.”

                       14                                         

(citation omitted)); , 2006 WL 826713, at *7 (M.D.

Ga. Mar. 28, 2006) (“ [ ] requires neither perfection from an expert nor
that he demonstrate a flawless methodology.”).

Regarding the acceptance of the equivalency methodology in the
scientific community, the Court is satisfied that DiFilippo’s methodology falls
within accepted scientific practice. In her rebuttal report, DiFilippo noted that
“[t]he concept of PFAS-equivalence, or equivalent concentration, is not novel
and is regularly used to evaluate the transformation of environmental
contaminants.” (DiFilippo Rebuttal Report, at 21.) Citing 3M’s own documents

and at least six other studies, DiFilippo explained that this equivalency
concept was frequently used by 3M and is “key” in assessing the likelihood that
PFAS precursors will degrade to terminal PFAS. ( ) She further explained
that analyses of PFAS in Aqueous Film Forming Foam (fire-suppressing foam
commonly used by firefighters) have relied on PFOS and PFOA equivalents.
(Daikin’s DiFilippo Dep. Excerpts, at 49:10–21.) And she identified at least a
dozen examples of additional scientific studies involving the equivalency

concept, including studies focused on degradation of other environmental
contaminants and by organizations such as the U.S. Geological Survey and
EPA. ( ) While DiFilippo’s methodology may not be widely used in her field,
it is sufficient that she has shown it has been used and tested across a number
of relevant publications and reputable entities. , 509 U.S. at 593 15

(noting that the factors are not a “definitive checklist”);

, 526 U.S. at 153 (acknowledging the district court’s “broad latitude”
in making reliability findings). And it is of little importance that DiFilippo

could not immediately identify studies by the EPA or state environmental
agencies during her deposition. With these findings in mind, the Court denies
the Defendants’ Motion to Exclude DiFilippo’s opinions on PFOS and PFOA
equivalents.

C. 3M Products as the Source of Raccoon Creek’s PFOA

3M argues that “Dr. DiFilippo should not be permitted to testify that

FC-248 has contributed to PFOA in biosolids fields upstream of Summerville’s
drinking water intake.” (Def. 3M’s Mot. to Exclude DiFilippo, at 16.) The
Plaintiffs respond that DiFilippo has not presented such an opinion and does
not plan to do so at trial. (Pls.’ Resp. Br. in Opp’n to Def. 3M’s Mot. to Exclude
DiFilippo, at 20.) Upon review of DiFilippo’s testimony, the Court agrees with
the Plaintiffs that DiFilippo has not offered an opinion on this topic. In fact,
this section of 3M’s brief merely cites DiFilippo’s deposition in which she

disclaimed opining on this topic and acknowledged doing so would amount to
speculation on her part. ( Def. 3M’s Mot. to Exclude DiFilippo, Ex. D (“3M’s
2024 DiFilippo Dep. Excerpts”), at 218:17–219:20 [Doc. 872-5].) The Court
therefore denies 3M’s Motion to Exclude as to this argument.

                       16                                         

D. “Rebranded” Daikin Products

Daikin asks this Court to exclude DiFilippo’s opinions that (1) other
companies bought and rebranded Daikin’s products and then sold them to

Mount Vernon Mills, and (2) “Daikin chemicals made up 67% of Mount Vernon
Mills’ total use of PFAS precursors from 1995 to 2012.” (Def. Daikin’s Mot. to
Exclude DiFilippo, at 12–21.) Daikin challenges these opinions on three
grounds: helpfulness, qualification, and reliability. As to helpfulness, it
contends that a jury could just as easily evaluate the same “non-scientific
documents” that DiFilippo reviewed in forming these opinions. ( at 12–13.)

As to qualification, Daikin points out that DiFilippo is a water and soil expert,
not an expert on “the buying or manufacturing practices of chemical
companies.” ( at 14.) As to reliability, the company argues that DiFilippo
makes an unsupported “inferential leap” by concluding from limited evidence
that five of the products Mount Vernon Mills bought over the years contained
Daikin chemicals. ( at 15–21.)

First, although a jury can evaluate non-scientific documents on its own

in most cases, the Court finds that an expert’s assessment of the documents
here would be helpful given their technical nature. They involve various
chemical compositions, chemical properties, and other unfamiliar terms,9

9 In an effort to show that the documents are not highly technical,
Daikin’s reply brief includes portions of one sales report and one product
formulation key. While the Court agrees that those two portions may not
17

which are “beyond the understanding of the average lay person.” , 387 F.3d at 1262. The Court itself has difficulty understanding the terminology
in these documents.

Second, the Court holds that DiFilippo is qualified to identify the
products used by Mount Vernon Mills that contained Daikin formulations and
to opine on the percentage of long-chain fluorotelomer polymers attributable
to Daikin. DiFilippo identified product trade names and chemical formulations
from company records and testimony, then matched both to records of total
pounds bought by MVM over time. The technical part is understanding

Daikin’s formulations and identifying whether they were present in other
companies’ products, which she applies her expertise to do. For example, she
opines that Pulcra Chemicals’s (“Pulcra”) “Repellant KTW” was a blend
between Daikin’s TG-581 and certain other agents. (DiFilippo Report, at 17.)
She also categorized various formulations by polymer type to determine the
number of pounds of long-chain fluorotelomer polymers attributable to each
company, which led to DiFilippo’s conclusion that 67% of long-chain

fluorotelomer polymers were attributable to Daikin. ( DiFilippo Report, at
57–58 tbls. 3–4.) DiFilippo need not hold particular expertise in “commercial

appear overly technical, the Court’s review of several of the other documents
reveals a number of sufficiently technical documents. ( , Def. Daikin’s
Mot. to Exclude DiFilippo, Exs. 6–7, 9–10 [Docs. 895-7, 895-8, 895-9, 895-10].)

                       18                                         

chemical sales” nor have “worked in-house for a chemical company” to form
these opinions. ( Def. Daikin’s Mot. to Exclude DiFilippo, at 14.)

Third, the Court agrees that some of DiFilippo’s opinions about the

“rebranded” Daikin products may be inadmissible. According to DiFilippo, five
Daikin formulations were present in the “long-chain fluorotelomer polymer”
products sold to Mount Vernon Mills between 1995 and 2012:

1. TG-470 sold by Apexical Specialty Chemicals (“Apexical”) as
Gardapex 115 (“Gardapex”) and Glo-Guard 15X (“Glo-Guard”);

2. TG-472 sold by Apexical as Waterproofon 242-M (“Waterproofon”);

1. TG-571 sold by Ciba as Zonyl 7714 and sold by Piedmont Chemical
   Industries (“Piedmont”) as Pomoguard FC500 (“Pomoguard”);
   
2. TG-581 blended with another agent and sold by Pulcra as Repellant KTW; and
   
3. TG-5130 sold by Sequa/Omnova as Sequapel CQR-46 (“Sequapel”).
   (DiFilippo Report, at 43 fig. 5, 57 tbl. 3.) Daikin challenges DiFilippo’s basis for concluding that four of these Daikin formulations were “rebranded” into

products by other companies: TG-470 as Gardapex and Glo-Guard; TG-472 as
Waterproofon; TG-571 as Pomoguard; and TG-5130 as Sequapel. Nonetheless,
the Court concludes that Defendant’s objections to this testimony will be more
appropriately handled by objections at trial rather than on a motion to exclude.

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E. 3M’s and Daikin’s Knowledge of PFAS

The Defendants seek to exclude DiFilippo’s opinion that Daikin and 3M
knew for decades that their products would be discharged into the environment

as PFAS-laden wastewater. (Def. Daikin’s Mot. to Exclude DiFilippo, at 22–25;
Def. 3M’s Mot. to Exclude DiFilippo, at 17.) Daikin seeks to further exclude
DiFilippo’s opinion in her rebuttal report that “Daikin knew products [it] sold
to distributors, formulators and competitors were being used in formulations
sold to various industries, including textile mills.” (DiFilippo Rebuttal Report,
at 25.) According to the Defendants, DiFilippo’s state-of-mind opinions are

(1) unhelpful to a jury, which can assess knowledge from its own review of the
relevant documents, (Def. Daikin’s Mot. to Exclude DiFilippo, at 22–23), (2) not
within the scope of DiFilippo’s expertise as a hydrologist, ( at 24), and
(3) unreliable guesswork “about important dates based on unspecific
documents,” ( at 24–25).

The Court begins and ends with the helpfulness inquiry. “An expert
cannot speculate as to an individual’s state of mind. Speculative state of mind

statements are not admissible as expert testimony because they are legal
conclusions as to another person's state of mind and thus are not of the type of
evidence that a jury needs the assistance of an expert to understand.”

, 644 F. Supp. 3d 1316, 1343 (N.D. Ga. 2022) (citation

modified). Instead, “the jury should hear and/or see firsthand any relevant

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evidence pertaining to the Defendant’s intent. Then the jury . . . should
consider the facts and make its own determination regarding [the]
[d]efendant’s intent.” , 2015 WL 2062611, at *4 (M.D.

Fla. May 4, 2015) (citation omitted).

The Court agrees with the Defendants that DiFilippo offers some
inadmissible conclusions about the Defendants’ knowledge and state of mind.
These include (1) Opinions 4–5 in Section 2 of DiFilippo’s report10 and other
explicit statements about the Defendants’ knowledge offered in the “Industry
Knowledge of PFAS in Wastewater and Biosolids” section of her report,

(DiFilippo Report, at 10, 20–21); (2) her rebuttal report opinion that “Daikin
knew products they sold to distributors, formulators and competitors were
being used in formulations sold to various industries, including textile mills,”
(DiFilippo Rebuttal Report, at 25); and (3) similar statements expressed in
DiFilippo’s testimony, ( , 3M’s 2024 DiFilippo Dep. Excerpts, at 192:17–
23, 193:12–194:5). DiFilippo’s initial and rebuttal reports make clear that she
came to these conclusions about the Defendants’ knowledge based on her

10 Opinion 4 states: “Manufacturers of PFAS-containing products have
long known that products used in the textile industry contained precursors
that would transform to terminal compounds, such as [PFOS] and [PFOA],

that would not degrade further.” (DiFilippo Report, at 10.) Opinion 5 states:
“Manufacturers of PFAS-containing products have long known their products,
when discharged to conventional wastewater treatment plants, sorb to sludge
and contaminate soils, surface water, and groundwater with PFAS when the
sludge is applied to land as biosolids.” ( )

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review of company documents and deposition testimony—rather than through
first-hand experience or other specialized expertise about the companies—and
she has testified to as much. ( DiFilippo Report, at 20–21; DiFilippo

Rebuttal Report, at 25–26; 3M’s 2024 DiFilippo Dep. Excerpts, at 192:20–
193:4, 194:6–19.) As a result, a jury is just as well positioned as DiFilippo to
make determinations about the Defendants’ level of knowledge over time.
Notwithstanding the above, the Court notes that DiFilippo’s efforts to
summarize studies performed or possessed by the Defendants (or others)
remain admissible. For example, while DiFilippo’s “Industry Knowledge of

PFAS in Wastewater and Biosolids” section contains inadmissible conclusions
as to the Defendants’ knowledge, it also contains admissible descriptions of
PFAS studies performed or possessed by the Defendants. ( DiFilippo
Report, at 20–21.) DiFilippo’s discussion of these studies and their results is
helpful to a jury, which would otherwise have difficulty interpreting their
meaning. From there, a jury could then assess for itself whether the
Defendants’ possession of relevant research is indicative of some level of overall

knowledge. , , 96 F. Supp. 3d 1307, 1333 (M.D. Fla. 2015) (declining to admit an expert’s testimony on the defendant’s
“intent or motivations,” but admitting testimony “that merely discusses what
information was available and possessed by” the defendant]”);

, 169 F. Supp. 396, 479 (S.D.N.Y. 2016) (admitting

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expert testimony to the extent it opined on the documents that were in the
defendant’s “possession”); In re Aqueous Film-Forming Foams Prods. Liab.
Litig., 2023 WL 3517923, at *3 (D.S.C. May 2, 20238).
IV. Conclusion
For the foregoing reasons, the Court DENIES Defendant 3M Company’s
Motion to Exclude the Expert Testimony of Erica DiFilippo [Doc. 872] and
GRANTS in part and DENIES in part Defendant Daikin America, Inc., E.I.
DuPont de Nemours and Company, and The Chemours Company’s Motion to
Exclude the Expert Testimony of Erica DiFilippo [Doc. 894].
SO ORDERED, this 26th day of March, 2026.

                                      tarmcee  D2       4 
                                    THOMAS W. THRASH, JR. 
                                    United States District Judge 

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