Pluck v. BP Oil Pipeline Co.

RECOMMENDED FOR FULL-TEXT PUBLICATION
Pursuant to Sixth Circuit Rule 206
File Name: 11a0121p.06

UNITED STATES COURT OF APPEALS
FOR THE SIXTH CIRCUIT
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Plaintiffs-Appellants, -
SUE PLUCK; RAY PLUCK,
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No. 09-4572
v.
,
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Defendant-Appellee. -
BP OIL PIPELINE COMPANY,
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Appeal from the United States District Court
for the Northern District of Ohio at Akron.
No. 08-01545—John R. Adams, District Judge.
Argued: March 2, 2011
Decided and Filed: May 12, 2011
Before: GILMAN, GIBBONS, and COOK, Circuit Judges.

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COUNSEL
ARGUED: Thomas R. Houlihan, AMER CUNNINGHAM CO., L.P.A., Akron, Ohio,
for Appellants. Robin G. Weaver, SQUIRE, SANDERS & DEMPSEY L.L.P.,
Cleveland, Ohio, for Appellee. ON BRIEF: Thomas R. Houlihan, AMER
CUNNINGHAM CO., L.P.A., Akron, Ohio, for Appellants. Robin G. Weaver,
SQUIRE, SANDERS & DEMPSEY L.L.P., Cleveland, Ohio, for Appellee.
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OPINION
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JULIA SMITH GIBBONS, Circuit Judge. In this toxic tort case alleging
exposure to benzene, plaintiffs-appellants Sue and Ray Pluck appeal the district court’s
order granting summary judgment to defendant-appellee BP Oil Pipeline Company
(“BP”). The Plucks challenge the district court’s grant of BP’s motion in limine to
exclude the testimony of their specific-causation expert, Dr. James Dahlgren, as

1
No. 09-4572 Pluck, et al. v. BP Oil Pipeline Company Page 2

unreliable under Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993).
They also argue that the district court should have admitted Dahlgren’s supplemental
declaration, which contradicted his prior testimony and was untimely filed. Based upon
these arguments, the Plucks contend that the district court erred in granting summary
judgment to BP. For the reasons that follow, we affirm the district court in all respects.

I.

This case arose from benzene contamination allegedly caused by gas-pipeline
releases near the Weaver Woodlands allotment in Franklin Township, Summit County,
Ohio. Between 1948 and 1962, an underground pipeline owned by BP that passed
through Franklin Township experienced five spills, resulting in the seepage of gasoline
into the surrounding soil and groundwater. In 1990, following reports of drinking water
contamination in Weaver Woodlands, BP entered into a voluntary agreement with the
Ohio Environmental Protection Agency (“OEPA”) to investigate the source and extent
of the contamination. Testing revealed the presence of benzene in the wells of nine
residents in concentrations exceeding the OEPA’s safe drinking water standards;
however, benzene was not detected in the well located at 605 Fairwood in Weaver
Woodlands. Benzene, a component of gasoline, is “a known carcinogen in sufficient
doses,” which is “also ubiquitous in the ambient air and is a component or constituent
of vehicle exhaust and cigarette smoke.” Baker v. Chevron USA, Inc., 680 F. Supp. 2d
865, 870 (S.D. Ohio 2010) (citing Indus. Union Dep’t, AFL-CIO v. Am. Petroleum Inst.,
448 U.S. 607, 615–16 (1980)).

In an effort to remediate the contamination, BP excavated areas of contaminated
soil, constructed monitoring wells, and conducted ongoing soil and water testing in the
area. BP conducted only a monitoring strategy with respect to 605 Fairwood, which had
been designated as an “area of concern” because of its “hydraulically downgradient”
position from 604 Fairwood, where benzene contamination was present. In 1995, the
owners of the property at 605 Fairwood sued BP for alleged contamination; BP agreed
to purchase this property, and several others, in settlement. See Facemire v. BP Am.,
Inc., No. CV-1995-01-0159 (Summit Cnty. Ct. Common Pleas filed Jan. 13, 1995).
No. 09-4572 Pluck, et al. v. BP Oil Pipeline Company Page 3

A.

In May 1996, Sue and Ray Pluck purchased the home at 605 Fairwood, where
they used the well water to drink, wash, shower, and irrigate their yard and garden. In
October 1996, around the time that the Plucks noticed a gasoline odor in their home and
water, benzene was first detected in the well on their property in the amount of 3.6 parts
per billion (“ppb”).1 At this time, Mrs. Pluck began drinking bottled water in lieu of tap
water, although she claims to have resumed drinking tap water upon the drilling of a
new, deeper well. BP installed the new well in December 1996 and tested it on a
quarterly basis; the company states, and the Plucks do not dispute, that between 1997
and May 2002, the new well tested negative for benzene twenty-two times. In October
2003, benzene measuring 1.8 ppb was detected in the new well, and a carbon filtration
system was installed to capture the contaminant. In 2005, the Plucks moved from 605
Fairwood upon the recommendation of Mrs. Pluck’s physician.

Mrs. Pluck was diagnosed with Non-Hodgkins lymphoma (“NHL”) in 2002 at
age forty-eight. Following chemotherapy in October 2002, the cancer went into
remission for five years. Mrs. Pluck later experienced a recurrence in 2007 but was
again in remission as of January 2009.

B.

The Plucks filed suit in the Summit County Court of Common Pleas on June 24,
2008, and BP thereafter removed the case to federal court.2 See Pluck v. BP Am., Inc.,
No. 5:08-cv-01707 (N.D. Ohio removed July 16, 2008). On June 26, 2008, the Plucks
filed a nearly identical suit in the United States District Court for the Northern District
of Ohio, alleging claims of strict liability for hazardous activity, negligence, and loss of
consortium. The district court granted BP’s motion to consolidate the cases and ordered

1
The EPA’s maximum permissible contaminant level for benzene is 5 ppb. 40 C.F.R.
§ 141.61(a)(2).
2
The plaintiffs first filed these claims in the Summit County Court of Common Pleas in June
2006, after which the case was removed by BP to federal district court. On June 27, 2007, the parties
stipulated to the dismissal of the claims without prejudice pursuant to Fed. R. Civ. P. 41(a). See Pluck v.
BP Am., Inc., No. 5:06-cv-01444 (N.D. Ohio dismissed June 27, 2006).
No. 09-4572 Pluck, et al. v. BP Oil Pipeline Company Page 4

the Plucks to file an Amended Complaint, which they did on October 31, 2008. In their
Amended Complaint, the Plucks once again alleged claims of strict liability for
hazardous activity, negligence, and loss of consortium on behalf of Mr. Pluck, all based
upon Mrs. Pluck’s alleged benzene exposure. BP denied these allegations in its Answer.
Pursuant to the case management plan, the district court then established a discovery
deadline of December 15, 2008, for expert reports and cautioned that “an expert will not
be permitted to testify or provide opinions on issues not raised in his/her report.”

To support their claims, the Plucks retained Drs. James Dahlgren and Joseph
Landolph as experts on causation to demonstrate that benzene is generally capable of
causing NHL and specifically caused Mrs. Pluck’s NHL. As to specific causation,
Dahlgren opined in his report “to a reasonable degree of medical certainty that Sue
Pluck’s [NHL] was caused or contributed to be caused by benzene from the BP
refinery.”3

On April 15, 2009, BP filed two motions in limine to exclude the testimony of
Dahlgren and Landolph on the grounds that their testimony failed to satisfy the standard
for reliability set forth in Daubert. In particular, BP argued that Dahlgren’s testimony
was unreliable “because he formulated a specific causation opinion without evidence of
dose, and subsequently performed an unreliable dose reconstruction in an attempt to
support his opinion.” BP also moved for summary judgment on the same date, arguing
that, under Ohio law, “[w]ithout expert testimony to establish both general causation and
specific causation, a claimant cannot establish a prima facie case of exposure to . . . toxic
substance[s].” Terry v. Caputo, 875 N.E.2d 72, 79 (Ohio 2007). Approximately one
month after BP filed its Daubert motions and motion for summary judgment, Dahlgren
submitted a supplemental declaration in which he evaluated Mrs. Pluck’s illness under
a differential-diagnosis methodology.

On November 25, 2009, the district court issued an order granting all of BP’s
motions and dismissing the Plucks’ case with prejudice. With respect to specific

3
As there is no refinery near Weaver Woodlands, Dahlgren presumably is referring to the
pipeline.
No. 09-4572 Pluck, et al. v. BP Oil Pipeline Company Page 5

causation, the court rejected Dahlgren’s testimony as unreliable under Daubert, stating
that it “suffer[ed] significant methodological flaws and [was] apparently based upon
speculation and conjecture rather than evidence and data.”4 The court premised its
opinion on the following: Dahlgren formulated his opinion on dose “without any
exposure data, only having been told that [Pluck] had been ‘heavily’ exposed to benzene
in her water”; he relied upon a “no safe dose” theory that had been discredited by other
courts as a basis for establishing specific causation; he could not explain the “scribbles”
used to calculate Mrs. Pluck’s dose of benzene; and he filed an untimely supplemental
declaration that contradicted his previous testimony and employed “an entirely new
differential diagnosis methodology that was not mentioned at any point prior to the
submission of his declaration.” The court also excluded Dahlgren’s untimely
supplemental declaration, finding that it “provid[ed] no additional information that
would assist . . . in making a reliability determination based upon testimony or opinions
previously offered.” After the district court granted summary judgment, the Plucks
timely appealed.

II.

We “review the exclusion of expert testimony for abuse of discretion, even when
the exclusion results in the entry of summary judgment for the opposing party.” Meridia
Prods. Liab. Litig. v. Abbott Labs., 447 F.3d 861, 868 (6th Cir. 2006) (citing Kumho Tire
Co. v. Carmichael, 526 U.S. 137, 152–53 (1999); Nelson v. Tenn. Gas Pipeline Co., 243
F.3d 244, 248 (6th Cir. 2001)). “A district court abuses its discretion if it bases its ruling
on an erroneous view of the law or a clearly erroneous assessment of the evidence.” Ky.
Speedway, LLC v. Nat’l Ass’n of Stock Car Auto Racing, Inc., 588 F.3d 908, 915 (6th
Cir. 2009) (internal quotation marks omitted). Accordingly, “we will not substitute our
own judgment for that of the district court and will reverse an evidentiary decision only
where we are left with a definite and firm conviction that [the district court] committed

4
The district court assumed “[f]or purposes of this analysis only,” that Landolph’s testimony
established general causation. It noted, however, that to the extent Landolph opined on specific causation,
he relied “upon the purported methods and findings of Dahlgren.” On appeal, the Plucks challenge the
district court’s evidentiary rulings only with regard to Dahlgren.
No. 09-4572 Pluck, et al. v. BP Oil Pipeline Company Page 6

a clear error of judgment.” In re Scrap Metal Antitrust Litig., 527 F.3d 517, 528 (6th
Cir. 2008) (alteration in original) (internal quotation marks omitted).

We review the district court’s grant of summary judgment de novo. Allen v.
Highlands Hosp. Corp., 545 F.3d 387, 393 (6th Cir. 2008). Summary judgment is
proper where no genuine issue of material fact exists, and the moving party is entitled
to judgment as a matter of law. Fed. R. Civ. P. 56(c). In considering a summary
judgment motion, “the district court must draw all reasonable inferences in favor of the
nonmoving party.” Ky. Speedway, 588 F.3d at 915 (citing Matsushita Elec. Indus. Co.
v. Zenith Radio Corp., 475 U.S. 574, 587 (1986)). “The central issue is ‘whether the
evidence presents a sufficient disagreement to require submission to a jury or whether
it is so one-sided that one party must prevail as a matter of law.’” Id. (quoting Anderson
v. Liberty Lobby, Inc., 477 U.S. 242, 251–52 (1986)).

III.

The Plucks raise two arguments on appeal. They dispute the district court’s
exclusion of Dahlgren’s specific-causation opinion as unreliable under Daubert, arguing
that the court improperly demanded precise data regarding Mrs. Pluck’s dose of benzene
and ignored Dahlgren’s differential-diagnosis methodology, which formed the basis of
his opinion. The Plucks also challenge the district court’s exclusion of Dahlgren’s
supplemental declaration, which was filed five months after the discovery deadline for
expert reports. In response, BP contends that the district court properly excluded
Dahlgren’s opinion, which failed to quantify Mrs. Pluck’s dose and “failed to account
for confounding factors,” including other sources of benzene exposure. BP also
maintains that the district court recognized differential diagnosis as a reliable
methodology for establishing specific causation but concluded that Dahlgren employed
this methodology in his untimely supplemental declaration only “after he had already
arrived at his specific causation conclusion.”

In a toxic-tort case, as here, the plaintiff must establish both general and specific
causation through proof that the toxic substance is capable of causing, and did cause, the
No. 09-4572 Pluck, et al. v. BP Oil Pipeline Company Page 7

plaintiff’s alleged injury.5 Meridia Prods., 328 F. Supp. 2d at 798. As to specific
causation, “[t]he plaintiff must show that [s]he was exposed to the toxic substance and
that the level of exposure was sufficient to induce the complained-of medical condition
(commonly called a ‘dose-response relationship’).” Valentine v. PPG Indus., Inc., 821
N.E.2d 580, 588 n.1 (Ohio Ct. App. 2004). Both causation inquiries involve scientific
assessments that must be established through the testimony of a medical expert. Baker,
680 F. Supp. 2d at 874; Terry, 875 N.E.2d at 77. Without this testimony, “a plaintiff’s
toxic tort claim will fail.” Baker, 680 F. Supp. 2d at 874.

Federal Rule of Evidence 702 governs the admission of expert testimony. It
provides:

If scientific, technical, or other specialized knowledge will assist the trier
of fact to understand the evidence or to determine a fact in issue, a
witness qualified as an expert by knowledge, skill, experience, training,
or education, may testify thereto in the form of an opinion or otherwise,
if (1) the testimony is based upon sufficient facts or data, (2) the
testimony is the product of reliable principles and methods, and (3) the
witness has applied the principles and methods reliably to the facts of the
case.

Fed. R. Evid. 702. In Daubert, the Supreme Court stated that the district court, when
evaluating evidence proffered under Rule 702, must act as a gatekeeper, ensuring “that
any and all scientific testimony or evidence admitted is not only relevant, but reliable.”
509 U.S. at 589. The district court must consider “whether the reasoning or
methodology underlying the testimony is scientifically valid.” Id. at 592–93.

We have explained that “Daubert attempts to strike a balance between a liberal
admissibility standard for relevant evidence on the one hand and the need to exclude
misleading ‘junk science’ on the other.” Best v. Lowe’s Home Ctrs., Inc., 563 F.3d 171,
176–77 (6th Cir. 2009). Although there is no “definitive checklist or test” to strike this
balance, the Daubert Court set forth factors relevant to the inquiry: (1) whether the
theory or technique can be or has been tested; (2) whether it “has been subjected to peer

5
While plaintiffs typically must first establish general causation, Terry, 875 N.E.2d at 76, the
district court assumed for purposes of its analysis that general causation had been established.
No. 09-4572 Pluck, et al. v. BP Oil Pipeline Company Page 8

review and publication”; (3) whether there is a “known or potential rate of error”; and
(4) whether the theory or technique enjoys general acceptance in the relevant scientific
community. 509 U.S. at 593–94. This inquiry is “a flexible one,” and the factors are
neither definitive nor exhaustive. Nelson, 243 F.3d at 251 (internal quotation marks
omitted). However, “[a]n expert who presents testimony must ‘employ[] in the
courtroom the same level of intellectual rigor that characterizes the practice of an expert
in the relevant field.’” Best, 563 F.3d at 177 (second alteration in original) (quoting
Kumho Tire, 526 U.S. at 152).

A.

The Plucks first argue that the district court improperly excluded Dahlgren’s
specific-causation opinion based upon his failure to quantify Mrs. Pluck’s dose of
benzene exposure. The Plucks concede that Dahlgren did not establish dose; they
instead argue that Dahlgren used differential diagnosis to determine specific causation
and that the district court “ignore[d] the ability of a physician to apply causal and
probabilistic reasoning to arrive at a differential diagnosis and offer an opinion on
specific causation.” In response, BP maintains that Dahlgren did not apply differential
diagnosis in either his expert opinion or his deposition, but did so only in an untimely
supplemental declaration filed five months after the deadline for expert reports. The
district court agreed with BP’s argument, stating that the record made clear “that
Dahlgren’s declaration disclosed an entirely new differential diagnosis methodology that
was not mentioned at any point prior to the submission of his declaration.” We also
agree.

This circuit has recognized differential diagnosis as an “appropriate method for
making a determination of causation for an individual instance of disease.” Hardyman
v. Norfolk & W. Ry. Co., 243 F.3d 255, 260 (6th Cir. 2001); see also Best, 563 F.3d at
178 (stating that a causation opinion based upon a reliable differential diagnosis may
satisfy the requirements of Rule 702). Differential diagnosis is “a standard scientific
technique of identifying the cause of a medical problem by eliminating the likely causes
until the most probable one is isolated.” Hardyman, 243 F.3d at 260 (internal quotation
No. 09-4572 Pluck, et al. v. BP Oil Pipeline Company Page 9

marks omitted). As we explained in Best, a physician who applies differential diagnosis
to determine causation “considers all relevant potential causes of the symptoms and then
eliminates alternative causes based on a physical examination, clinical tests, and a
thorough case history.” 563 F.3d at 178 (internal quotation marks omitted).

In this case, the Plucks acknowledge that Dahlgren did not explicitly identify
differential diagnosis as his methodology until filing his supplemental declaration, but
they argue that he identified and ruled out alternative causes for Mrs. Pluck’s NHL
“without necessarily using the term ‘differential diagnosis.’” Yet, merely claiming that
an expert used differential diagnosis is alone insufficient to satisfy the reliability inquiry
under Daubert. See Tamraz v. Lincoln Elec. Co., 620 F.3d 665, 674 (6th Cir. 2010),
petition for cert. filed, 79 U.S.L.W. 3554 (U.S. Mar. 9, 2011) (No. 10-1122); see also
Best, 563 F.3d at 179 (cautioning that “[n]ot every opinion that is reached via a
differential-diagnosis method will meet the standard of reliability required by Daubert”).
Rather, we stated in Tamraz that

[c]alling something a “differential diagnosis” or “differential etiology”
does not by itself answer the reliability question but prompts three more:
(1) Did the expert make an accurate diagnosis of the nature of the
disease? (2) Did the expert reliably rule in the possible causes of it?
(3) Did the expert reliably rule out the rejected causes? If the court
answers “no” to any of these questions, the court must exclude the
ultimate conclusion reached.

620 F.3d at 674. Here, the parties do not dispute the accuracy of Mrs. Pluck’s NHL
diagnosis. Accordingly, to determine whether Dahlgren performed a differential
diagnosis satisfying the requirements of Rule 702, we must evaluate whether Dahlgren
reliably “ruled in” the potential causes of Mrs. Pluck’s NHL and “ruled out” alternative
causes.

In Tamraz, we rejected an expert witness’s causation testimony, which sought
to demonstrate that manganese exposure caused the plaintiff’s Parkinson’s disease, as
unreliable under Daubert and, therefore, inadmissible. Id. We stated that the expert’s
opinion was unreliable because “his efforts to ‘rule in’ manganese exposure as a possible
cause or to ‘rule out’ other possible causes turned on speculation, not a valid
No. 09-4572 Pluck, et al. v. BP Oil Pipeline Company Page 10

methodology.” Id. In particular, we observed that the expert’s hypothesis concerning
the relationship between manganese exposure and Parkinson’s disease, albeit plausible,
was based upon speculation and was not the “product of reliable principles and
methods,” as is required by Rule 702. Id. at 670 (internal quotation marks omitted).
Thus, we concluded that “no matter the label,” the expert’s testimony “[did] not satisfy
Rule 702.” Id. at 674.

Regardless of how the Plucks characterize Dahlgren’s causation analysis, his
expert opinion likewise failed to meet the requirements of Rule 702. Foremost,
Dahlgren could not reliably “rule in” benzene as the cause of Mrs. Pluck’s NHL. In
recognition of the fact that benzene poses a health concern at certain levels of exposure,
the EPA has stated that the maximum permissible contaminant level for benzene in
drinking water is 5 ppb. 40 C.F.R. § 141.61(a)(2). Dahlgren, however, did not ascertain
Mrs. Pluck’s level of benzene exposure, nor did he determine whether she was exposed
to quantities of benzene exceeding the EPA’s safety regulations. To the contrary,
Dahlgren admitted that he “ha[d] limited exposure data” and that the “[r]esults of soil
and water tests from the EPA for the Pluck’s [sic] property [were] still pending.”
Nevertheless, he concluded that “chronic low-level exposure can and does cause NHL”;
that Mrs. Pluck “probably had an injurious exposure to benzene and other organic
solvents considerably above background”; and that “[t]here is no safe level for benzene
in terms of causing cancer.” We find this analysis unpersuasive, particularly because the
levels of benzene in the Plucks’ wells never exceeded the maximum permissible
contaminant level of 5 ppb designated by the EPA. Dahlgren’s opinion that Mrs. Pluck’s
“low-level exposure” to benzene caused her NHL is not grounded in “sufficient facts or
data,” nor does it reflect the “reliable principles and methods” required by Rule 702. It
is, instead, pure conjecture.

Although the Plucks argue that the district court required too much specificity
regarding Mrs. Pluck’s dose, this argument is without merit. In Nelson, we upheld the
district court’s exclusion of a causation expert’s testimony in a case alleging injury due
to exposure to polychlorinated biphenyls (“PCBs”) following a gas-pipeline release. 243
No. 09-4572 Pluck, et al. v. BP Oil Pipeline Company Page 11

F.3d at 246. We remarked that the causation expert, like Dahlgren, “made no attempt
to determine what amount of PCB exposure the . . . subjects had received and simply
assumed that it was sufficient to make them ill.” Id. at 252. Thus, because there was no
“factual basis from which a jury could infer that the plaintiffs were in fact exposed to
PCBs,” we deemed the expert’s methodology scientifically unreliable. Id. at 253.

Although the Plucks contend that evidence of benzene exposure existed by virtue
of its presence in their wells in 1996 and 2003, it is well-settled that the mere existence
of a toxin in the environment is insufficient to establish causation without proof that the
level of exposure could cause the plaintiff’s symptoms. See id. at 252–53 (noting that
the presence of PCBs in the plaintiffs’ environment “in excess of allowable limits” could
not establish causation without evidence that they were “exposed at a level that could
cause neurological and lung impairments”); McClain v. Metabolife Int’l, Inc., 401 F.3d
1233, 1242 (11th Cir. 2005) (stating that causation “requires not simply proof of
exposure to the substance, but proof of enough exposure to cause the plaintiff’s specific
illness”). Here, Dahlgren offered no such evidence. Rather, in attempting to estimate
Mrs. Pluck’s exposure, Dahlgren relied upon a gasoline-vapor-concentration study that
discussed the correlation between benzene exposure and leukemia. See Ami S. Patel et
al., Risk of Cancer as a Result of Community Exposure to Gasoline Vapors, 59 Archives
Envtl. Health 497 (2004). Citing this study, Dahlgren stated that Mrs. Pluck “was
exposed to a concentration of benzene . . . 129 times higher than the Patel study would
indicate increases the risk of . . . leukemia fourfold.” Yet, when asked to explain the
methodology for his calculations, Dahlgren admitted that he could not do so, as he was
“not sure about any of these scribbles.” Moreover, Dahlgren failed to mention that the
Patel study “did not find a statistically significant association between NHL and residing
near a gasoline spill.” See also Baker, 680 F. Supp. 2d at 886–87 (rejecting Dahlgren’s
reliance upon Patel’s study as a basis for his causation opinion and noting that “[t]here
was not a statistically significant increase in [NHL]” following prolonged periods of
benzene exposure). The district court thus concluded, as do we, that Dahlgren’s attempt
to determine Mrs. Pluck’s level of benzene exposure “[did] not represent a scientifically
reliable methodology.”
No. 09-4572 Pluck, et al. v. BP Oil Pipeline Company Page 12

Finally, even if Dahlgren had properly “ruled in” benzene exposure as the cause
of Mrs. Pluck’s NHL, he failed to “rule out” alternative causes of her illness, as is
required under the differential-diagnosis methodology. See Tamraz, 620 F.3d at 674
(stating that an expert’s opinion must be rejected if the expert failed to rule out
alternative causes of the plaintiff’s illness). In Nelson, for example, we found “simply
no basis” to assume that exposure to PCBs caused the plaintiffs’ illnesses when the
causation expert failed to account for confounding factors, including alcohol use and
cigarettes, that might have produced such symptoms. 243 F.3d at 253 (internal quotation
marks omitted); see also Wills v. Amerada Hess Corp., 379 F.3d 32, 50 (2d Cir. 2004)
(noting that an expert’s opinion suffered from a “fatal flaw” when he acknowledged that
cigarettes and alcohol were risk factors for developing squamous-cell carcinoma but
“failed to account for these variables in concluding that decedent’s cancer was caused
by exposure to toxic chemicals such as benzene and PAHs”).

In this case, Dahlgren acknowledged in his deposition that Mrs. Pluck was
exposed to other sources of benzene, particularly from her extensive smoking habit. He
observed that cigarettes contain benzene; that smoking can contribute to elevated levels
of benzene exposure; and that he “[could not] tell from the existing data that her
cigarette smoking would have caused her to be at significantly increased risk for . . .
[NHL].” Dahlgren also opined that other organic solvents may pose a risk, and his
written opinion commented upon Mrs. Pluck’s “injurious exposure to benzene and other
organic solvents.” Yet, Dahlgren neither identified these “other” solvents nor
determined Mrs. Pluck’s potential level of exposure to them. Thus, Dahlgren failed to
“rule out” alternative causes of Mrs. Pluck’s NHL, and the district court did not abuse
its discretion in concluding that he did not perform a reliable differential diagnosis.

B.

The Plucks also argue that the district court erred in striking Dahlgren’s
supplemental declaration, in which he used differential diagnosis to evaluate the cause
of Mrs. Pluck’s NHL. Dahlgren filed his supplemental declaration on May 15,
No. 09-4572 Pluck, et al. v. BP Oil Pipeline Company Page 13

2009—one month after BP filed its Daubert motions and motion for summary judgment,
and five months after the district court’s December 15, 2008, deadline for the submission
of expert reports. The district court struck this declaration as untimely, contradictory to
Dahlgren’s previous specific-causation opinion, and reliant upon a new differential-
diagnosis methodology that Dahlgren failed to discuss within the permissible time frame
for filing expert reports.

Although it is undisputed that Dahlgren first identified differential diagnosis as
his causation methodology in his supplemental declaration, the Plucks maintain that
Dahlgren used differential diagnosis in his deposition without explicitly saying so. They
state that “Dahlgren was never asked in his deposition what his methodology was.”
These statements approximate the Plucks’ argument in the district court, in which they
relied upon GED Integrated Solutions, Inc. v. Durotech International, Inc. to argue that
Dahlgren’s supplemental declaration should be admitted beyond the December 15, 2008,
deadline for the submission of expert reports. No. 5:06CV1327, 2009 WL 233872 (N.D.
Ohio Jan. 30, 2009). In Durotech, the district court rejected a timeliness challenge to an
expert’s supplemental report on the grounds that it contained “nothing more than what
the Court would have learned had it held a formal hearing on this Daubert challenge”
and did “not include a new expert evaluation of any evidence.” Id. at *2. Here, the
district court properly concluded that, unlike in Durotech, Dahlgren’s report contradicted
his prior causation opinion and attempted “to introduce an entirely new methodology
well after the point at which it would be proper.” Indeed, as we discussed above,
Dahlgren did not use differential diagnosis in his expert opinion or deposition testimony
because he failed to reliably “rule in” benzene as the cause of Mrs. Pluck’s NHL and,
likewise, failed to “rule out” alternative causes, including smoking and exposure to other
solvents. See Best, 563 F.3d at 178. Thus, Dahlgren’s supplemental declaration served
as an untimely attempt to introduce a new causation methodology.

We have recognized that “[d]istrict courts have broad discretion to exclude
untimely disclosed expert-witness testimony,” particularly when these reports serve as
a “transparent attempt to reopen” the Daubert inquiry after the weaknesses in the
No. 09-4572 Pluck, et al. v. BP Oil Pipeline Company Page 14

expert’s prior testimony have been revealed. Pride v. BIC Corp., 218 F.3d 566, 578–79
(6th Cir. 2000) (internal quotation marks omitted). In this case, the district court did not
abuse its discretion in striking Dahlgren’s untimely supplemental declaration, in which
he attempted to bolster his deficient opinion by employing a new causation
methodology. We also conclude that, because Dahlgren did not provide a specific-
causation opinion satisfying the requirements of Rule 702, the district court did not err
in granting summary judgment on behalf of BP.

IV.

For the foregoing reasons, we affirm the judgment of the district court in all
respects.6

6
The Plucks claim in passing that the district court erroneously implied that Mrs. Pluck began
drinking bottled water exclusively in 1996 and “ignored other avenues of exposure to benzene in the
water—through dermal absorption and inhalation through showering, and through working the soil in her
garden.” They argue that these alleged omissions “painted a picture” that their lawsuit involved merely
an isolated incident of benzene exposure. However, contrary to this claim, the district court noted that the
Plucks “used their well water to drink, wash, bathe, and irrigate their lawn and garden.” Moreover,
although the district court correctly observed that Mrs. Pluck ceased drinking water from the contaminated
well upon smelling gasoline in 1996, it did not state that she did not drink from the new well. Thus, the
Plucks, who have cited no case law supporting their argument, have disregarded the district court’s
discussion of Mrs. Pluck’s benzene exposure. This argument is without merit.