Thiele v. BASF Corporation et al
MEMORANDUM Opinion and Order. Motion (Doc. 308 ) to exclude the testimony and opinions of Dr. Durrani is granted. Motion (Doc. 309 ) to exclude the testimony and opinions of Dr. Harrison is granted. Motion (Doc. 315 ) for summary judgment is gr anted. All other pending motions (Docs. 311 , 312 , 313 , 314 , 345 and 387 ) are denied as moot. The trial of this case, scheduled to begin 3/04/2022, is canceled. Because this order disposes of all remaining claims, this action is hereby dismissed. Signed by Chief Judge Leonard T Strand on 1/10/2022. (des)
IN THE UNITED STATES DISTRICT COURT
FOR THE NORTHERN DISTRICT OF IOWA
DSM FOOD SPECIALTIES, USA, INC.,
OPINION AND ORDER
This matter is before me on a motion (Doc. 315) for summary judgment by
defendant Givaudan Flavors Corporation (Givaudan). Plaintiff Jason Thiele has filed a
resistance (Doc. 361) to the motion and Givaudan has filed a reply. Doc. 381. Givaudan
has also filed the following motions to exclude expert testimony:
Doc. 308 – Motion to Exclude the Testimony and Opinions of Plaintiff’s
Expert Timur Durrani, M.D., as to General Causation and Warnings Related
to 2,3-Pentanedione and 2,3-Hexanedione
Doc. 309 – Motion to Exclude the Testimony and Opinions of Plaintiff’s
Expert Robert Harrison, M.D. as to General Causation
Doc. 311 – Motion to Exclude the Testimony and Opinions of Plaintiff’s
Expert Charles Pue, M.D. as to Specific Causation
Doc. 312 – Motion to Exclude Dr. Harrison’s Testimony and Opinions as to
Doc. 313 – Motion to Exclude the Testimony and Opinions of Plaintiff’s
Experts William H. Rogers, Ph.D. and John O. Ward, Ph.D.
Doc. 314 – Motion to Exclude the Testimony and Opinions of Plaintiff’s
Case 5:18-cv-04081-LTS-SHL Document 396 Filed 01/10/22 Page 1 of 22
Expert Katie Allison, PT, MS, CLCP
Doc. 387 – Motion in Limine to Exclude the Testimony and Opinions of
Gregory B. Diette, M.D.
Thiele has filed responses to each motion. See Docs. 337-339, 341-343, 391. Givaudan
has filed replies to all but the motion in limine. See Docs. 347, 349-353. Givaudan has
also provided notice (Doc. 394) of supplemental authority in support of its motions to
exclude the testimony and opinions of Dr. Durrani and Dr. Harrison and its motion for
summary judgment. Oral argument is not necessary. See Local Rule 7(c).
BACKGROUND AND PROCEDURAL HISTORY
Thiele filed his complaint on September 12, 2018, alleging diversity jurisdiction
under 28 U.S.C. § 1332. He asserts claims of negligence (Count I), strict product liability
– design, manufacturing and inherent defects (Count II), strict product liability – failure
to warn (Count III) and strict product liability – failure to instruct (Count IV). Doc. 1.
Thiele alleges he developed “flavoring-related bronchiolitis obliterans syndrome” or
“flavoring-related lung disease” from occupational exposure to flavors containing the
ingredients diacetyl, 2,3-pentanedione (2,3-PD) and 2,3-hexanedione (2,3-HD) while
working at American Pop Corn Company (APC) from March 2004 to May 2011.
Although Thiele’s complaint named numerous defendants, all but Givaudan have been
dismissed throughout the course of this case.
Motions to Exclude Expert Testimony and Opinion
Timur Durrani, M.D. – Doc. 308
Givaudan seeks to exclude the expert testimony and opinions of Dr. Durrani
pursuant to Federal Rules of Evidence 402, 403, 702 and 703. Specifically, it seeks to
exclude his testimony and opinions as to general causation and warnings related to 2,32
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PD and 2,3-HD. See Docs. 308, 318. Dr. Durrani has opined that (a) 2,3-PD and 2,3HD can cause bronchiolitis obliterans (BO) and other lung disease and (b) that the
defendants should have known, by at least 2002, that 2,3-PD and 2,3-HD were capable
of causing BO and other lung disease.
Givaudan notes that in 2000, the National Institute for Occupational Safety and
Health (NIOSH) became aware of several former employees of a microwave popcorn
facility in Jasper, Missouri, who had been diagnosed with BO. NIOSH was unable to
confirm the diagnoses or determine the exact cause of their lung conditions but suspected
that the ingredient diacetyl in the butter flavor might be associated with the BO diagnosed
in the former workers. BO is a rare, medically-recognized respiratory condition that is
found almost exclusively in lung transplant patients as a known complication. Former
popcorn plant employees generally do not meet the diagnostic criteria of BO. Dr. Charles
Pue, Thiele’s specific causation expert, created a diagnosis to reflect the flavoring-related
component, which has undergone various name changes, but is now referred to as
“flavoring-related lung disease (FRLD).1
The parties agree that Thiele must prove general and specific causation through
expert testimony to prevail on his claims.
Givaudan argues Dr. Durrani’s general
causation opinion should be excluded because:
a) he conceded that he was not offering any opinions related to FRBOS
b) not a single study he relies on concludes that 2,3-PD or 2,3-HD can cause BO
(or any other lung disease)
c) he lacks the requisite knowledge and basis on which to render any general
causation opinion with respect to 2,3-PD or 2,3-HD because he admits that he
cannot satisfy the two required elements of such an opinion, i.e., he does not
know the level of exposure to 2,3-PD or 2,3-HD that is capable of causing harm
or Thiele’s actual level of exposure to 2,3-PD or 2,3-HD
Dr. Pue diagnosed Thiele with “flavoring related bronchiolitis obliterans syndrome” (FRBOS)
but changed the diagnosis to FRLD in his amended report. Dr. Pue states this was just a “change
in nomenclature” such that the terms may be used interchangeably throughout his opinion.
Case 5:18-cv-04081-LTS-SHL Document 396 Filed 01/10/22 Page 3 of 22
Givaudan also seeks to exclude Dr. Durrani’s opinion that defendants should have known
by 2002 that 2,3-PD and 2,3-HD could cause BO.
Federal Rule of Evidence 702 governs the admission of expert testimony. The
rule states that a qualified expert may testify “in the form of an opinion or otherwise” if:
the expert’s scientific, technical, or other specialized knowledge will
help the trier of fact to understand the evidence or to determine a
fact in issue;
the testimony is based on sufficient facts or data;
the testimony is the product of reliable principles and methods; and
the expert has reliably applied the principles and methods to the facts
of the case
Fed. R. Evid. 702. To be admissible, expert testimony must be both relevant and
reliable. Weisgram v. Marley Co., 169 F.3d 514, 517 (8th Cir. 1999), aff’d, 528 U.S.
440 (2000). Evidence is relevant if it tends to make a fact more or less probable and is
of consequence in determining the action. Fed. R. Evid. 401. Evidence is reliable if it
is useful to the fact finder in deciding an ultimate issue of fact, the expert is qualified and
the expert’s evidence is reliable. Peters v. Woodbury Cnty., 979 F. Supp. 2d 909, 919
(N.D. Iowa 2013), aff’d sub nom. Peters v. Risdal, 786 F.3d 1095 (8th Cir. 2015).
Under Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993), the
district court must perform a “gatekeeping function” to ensure that irrelevant or
unreliable expert testimony is not introduced into evidence. See, e.g., In re Zurn Pex
Plumbing Prods. Liab. Litig., 644 F.3d 604, 613 (8th Cir. 2001). The trial court has
broad discretion when determining the reliability of expert testimony. United States v.
Vesey, 338 F.3d 913, 916 (8th Cir. 2003). Doubts as to whether the testimony will be
helpful should be resolved in favor of admissibility. See Shuck v. CNH America, LLC,
498 F.3d 868, 874 (8th Cir. 2007) (Rule 702 “is one of admissibility rather than
exclusion.)” (citation omitted)); Robinson v. GEICO Gen. Ins. Co., 447 F.3d 1096, 1100
Case 5:18-cv-04081-LTS-SHL Document 396 Filed 01/10/22 Page 4 of 22
(8th Cir. 2006) (“‘[R]ejection of expert testimony is the exception rather than the rule.’”
(quoting Fed. R. Evid. 702 advisory committee’s note)).
When considering expert testimony, the court must determine whether the
testimony is both reliable and relevant. See Barrett v. Rhodia, Inc., 606 F.3d 975, 980
(8th Cir. 2010) (citing Marmo v. Tyson Fresh Meats, Inc., 457 F.3d 748, 757 (8th Cir.
To satisfy the reliability requirement, the party offering the expert
testimony “must show by a preponderance of the evidence both that the
expert is qualified to render the opinion and that the methodology
underlying his conclusions is scientifically valid.” Daubert, 509 U.S. at
589-90. To satisfy the relevance requirement, the proponent must show
that the expert’s reasoning or methodology was applied properly to the facts
Khoury v. Philips Med. Sys., 614 F.3d 888, 892 (8th Cir. 2010) (citation omitted, cleaned
up). Factors bearing on the admissibility of expert evidence include:
(1) whether the theory or technique applied can be tested, (2) whether the
theory or technique has been subject to peer review and publication, (3) the
known or potential rate of error, and (4) whether it is accepted in the
Kuhn v. Wyeth, Inc., 686 F.3d 618, 625 (8th Cir. 2012) (citing Daubert, 509 U.S. at
593-94). The court may also consider “whether the expertise was developed for litigation
or naturally flowed from the expert’s research; whether the proposed expert ruled out
other alternative explanations; and whether the proposed expert sufficiently connected
the proposed testimony with the facts of the case.” Presley v. Lakewood Eng’g & Mfg.
Co., 553 F.3d 638, 643 (8th Cir. 2009) (citation omitted). “While weighing these
factors, the district court must continue to function as a gatekeeper who ‘separates expert
opinion evidence based on ‘good grounds’ from subjective speculation that masquerades
as scientific knowledge.’” Presley, 553 F.3d at 643 (citation omitted).
“Expert testimony is inadmissible where . . . it is excessively speculative or
unsupported by sufficient facts.” Onyiah v. St. Cloud State Univ., 684 F.3d 711, 720
Case 5:18-cv-04081-LTS-SHL Document 396 Filed 01/10/22 Page 5 of 22
(8th Cir. 2012) (citation omitted); see also Marmo, 457 F.3d at 757 (“Expert testimony
is inadmissible if it is speculative, unsupported by sufficient facts, or contrary to the facts
of the case.”); J.B. Hunt Transp., Inc. v. Gen. Motors Corp., 243 F.3d 441, 444 (8th
Cir. 2001) (“Expert testimony that is speculative is not competent proof and contributes
nothing to a legally sufficient evidentiary basis.”) (citation omitted)). An expert’s opinion
should be excluded only if it “‘is so fundamentally unsupported that it can offer no
assistance to the jury.’” Cole v. Homier Distrib. Co., 599 F.3d 856, 865 (8th Cir. 2010)
(citation omitted). Otherwise, “‘[v]igorous cross-examination, presentation of contrary
evidence, and careful instruction on the burden of proof are the traditional and appropriate
means of attacking shaky but admissible evidence.’” Kuhn, 686 F.3d at 625 (quoting
Daubert, 509 U.S. at 596).
I will first address Givaudan’s argument that Dr. Durrani does not know either (1)
the level of exposure to 2,3-PD or 2,3-HD that is capable of causing harm or (2) Thiele’s
actual level of exposure to 2,3-PD or 2,3-HD. Dr. Durrani’s opinion 2 has been excluded
on these grounds in a similar case, as has Dr. Harrison’s general causation opinion. See
Downs et al. v. DSM Food Specialties USA, Inc., et al., 1:18-cv-33, Doc. 468 (S.D.
Iowa Oct. 28, 2021).3 In Downs, the court noted that Dr. Durrani did not identify the
level of exposure to 2,3-PD and 2,3-HD that is harmful. Dr. Durrani testified in his
deposition that, although a threshold level of exposure at which these chemicals can cause
harm exists, he could not identify the threshold level because it is not known to the
scientific community and therefore unknown to him.
He therefore assumed that
occupational exposures to 2,3-PD and 2,3-HD are unsafe and capable of causing lung
Dr. Durrani acknowledged in his deposition that his report in Downs is substantially the same
or identical to the report he offers in this case. See Doc. 308-5 at 4.
The plaintiffs in Downs have not appealed the court’s ruling.
Case 5:18-cv-04081-LTS-SHL Document 396 Filed 01/10/22 Page 6 of 22
disease. Id. The Downs court found that this assumption made Dr. Durrani’s testimony
speculative and therefore inadmissible. Further, the court noted Dr. Durrani could not
identify the level of 2,3-PD and 2,3-HD to which someone working at the same plant as
the plaintiffs would have been exposed during work. The court concluded that without
this necessary evidence of causation, Dr. Durrani’s testimony was not reliable and
therefore excluded his opinion. Id.
Thiele relies on Herbst v. Givaudan Flavors Corp., No. C17-4008-MWB, 2018
WL 6310271, at *3 (N.D. Iowa Dec. 3, 2018), in which United States District Judge
Mark W. Bennett found that Dr. Harrison’s general causation opinion was not
inadmissible simply because it did not “identify the dosages at which diacetyl may be
harmful or the dosages to which Herbst was ever exposed.”
After that case was
reassigned to me, I found no grounds to reach a different outcome on reconsideration.
Herbst v. Givaudan Flavors Corp., No. C17-4008-LTS, 2019 WL 6108098, at *3 (N.D.
Iowa Aug. 19, 2019). Givaudan argues that the initial rationale for this standard, as
explained in Bonner,4 does not apply to this type of litigation, which has now been
ongoing for 20 years. Givaudan further contends that neither Dr. Durrani’s nor Dr.
Harrison’s opinions can meet the necessary standard when such opinions offer no
specificity about exposure levels. Thiele notes there are no historical measurements of
the chemicals at issue during Thiele’s employment.
“To prove causation in a toxic tort case, a plaintiff must show both that the alleged
toxin is capable of causing injuries like that suffered by the plaintiff in human beings
subjected to the same level of exposure as the plaintiff, and that the toxin was the cause
of the plaintiff’s injury.” Bonner, 259 F.3d at 928 (citing Wright v. Willamette Indus.,
See Bonner v. ISP Techs., Inc., 259 F.3d 924, 928 (8th Cir. 2001) (“We have held, however,
that ‘[t]he first several victims of a new toxic tort should not be barred from having their day in
court simply because the medical literature, which will eventually show the connection between
the victims’ condition and the toxic substance, has not yet been completed.”) (quoting Turner v.
Iowa Fire Equip. Co., 229 F.3d 1202, 1208-09 (8th Cir. 2000)).
Case 5:18-cv-04081-LTS-SHL Document 396 Filed 01/10/22 Page 7 of 22
Inc., 91 F.3d 1105, 1106 (8th Cir. 1996)). See also Bland v. Verizon Wireless, L.L.C.,
538 F.3d 893, 898 (8th Cir. 2008) (affirming exclusion of expert causation opinion where
expert lacked knowledge as to (1) what amount of exposure was capable of causing the
alleged injury and (2) what amount the plaintiff was actually or probably exposed). To
prove exposure levels, a plaintiff need not produce a “mathematically precise table
equating levels of exposure with levels of harm” but must make “a threshold showing
that he or she was exposed to toxic levels known to cause the type of injuries he or she
suffered.” Mattis v. Carlon Elec Prods., 295 F.3d 856, 860-61 (8th Cir. 2002) (quoting
Bednar v. Bassett Furniture Mfg. Co., 147 F.3d 737, 740 (8th Cir. 1998)). See also
Bonner, 259 F.3d at 931 (“it was not necessary that Bonner’s experts quantify the amount
of FoamFlush to which she was exposed in order to demonstrate that she was exposed to
a toxic level of BLO . . . . It is sufficient for a plaintiff to prove that she was exposed to
a quantity of the toxin that ‘exceeded safe levels.’”) (internal citation omitted); Bednar,
147 F.3d at 740 (“The Bednars did not need to produce ‘a mathematically precise table
equating levels of exposure with levels of harm’ in order to show Marian’s level of
exposure to gaseous formaldehyde, but only ‘evidence from which a reasonable person
could conclude that [the] defendant’s emission has probably caused’ the harm about which
In Wright, the court found that “while the Wrights proved that they were exposed
to defendant’s emissions and that wood fibers from defendant’s plant were in their house,
their sputum, and their urine, they failed to produce evidence that they were exposed to
a hazardous level of formaldehyde from the fibers emanating from Willamette’s plant.”
Wright, 91 F.3d at 1107. The court noted that plaintiffs’ experts offered testimony about
the levels of gaseous formaldehyde that might be expected to cause symptoms like the
ones that plaintiffs claimed to have experienced, but they did not claim to be injured from
breathing gaseous formaldehyde and made no reference to any studies that revealed the
levels of exposure to wood fibers impregnated with formaldehyde that would likely
produce adverse consequences. Id. at 1107-08. One expert testified that plaintiffs’
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complaints “were more probably than not related to exposure to formaldehyde, but the
court noted his opinion was not based on any knowledge about what amounts of wood
fibers impregnated with formaldehyde involved an appreciable risk of harm to human
beings who breathe them.” Id. at 1108.
In contrast, the plaintiffs in Bednar provided evidence of the threshold limit of
safe exposure to gaseous formaldehyde approved by the American Conference of
Governmental Industrial Hygienists, the average safety limit set by NIOSH for an eighthour period, and the safety limit recognized by the Occupational Safety and Health
Administration (OSHA) for an eight-hour average and any fifteen-minute period.
Bednar, 147 F.3d at 739. Their experts also testified about symptoms that could be
triggered by exposure over certain thresholds and at what point exposure to formaldehyde
could cause adverse health effects. Id. Finally, the plaintiffs presented evidence of tests
conducted by their expert that measured the level of a gaseous formaldehyde that was
found in the air of the dresser drawers at issue. Id. at 740. This expert also testified as
to the levels of formaldehyde that are considered unsafe, and that the gaseous
formaldehyde in the drawers exceeded safe limits. Id.
In Bonner, the court found that the plaintiff presented expert witnesses who
testified that her exposure to the product at issue was “of a duration and of a volume
sufficient to support a conclusion that she inhaled and/or absorbed through her skin at
least a quarter of a teaspoon of FoamFlush when she was sprayed with it.” Bonner, 259
F.3d at 931. The court stated that “it was not necessary that Bonner’s experts quantify
the amount of FoamFlush to which she was exposed in order to demonstrate that she was
exposed to a toxic level of BLO” and that it is “sufficient for a plaintiff to prove that she
was exposed to a quantity of the toxin that ‘exceeded safe levels.’” Id. (quoting Bednar,
147 F.3d at 740).
Here, Dr. Durrani opines that BO and “other lung disease” can occur due to
“massive chemical exposure or in a sub-acute chronic exposure.” Doc. 308-4 at 6. He
states that in 2002, NIOSH identified chronic exposure to diacetyl as the causative agent
Case 5:18-cv-04081-LTS-SHL Document 396 Filed 01/10/22 Page 9 of 22
in eight popcorn-plant workers in Missouri. Id. Peak exposures were measured up to
1230 ppm, such as when opening the lid of a tank of heated flavoring prior to mixing it
with heated oil. Id. Dr. Durrani then compares the chemical properties of diacetyl to
2,3-PD and 2,3-HD before discussing the Bradford Hill viewpoints 5 for each. Id. With
regard to 2,3-PD, Dr. Durrani discusses seven studies, none of which identify a level of
exposure at which 2,3-PD is harmful to humans. The closest Dr. Durrani comes to
providing such information is through the NIOSH proposed recommended exposure
limits (REL) for diacetyl and 2,3-PD:
The agency recommends a[n] exposure limit of 5 ppb for diacetyl as a timeweighted average for up to 8 hours/day during a 40-hour work week and a
short-term exposure limit of 25 parts per billion for a 15-minute time period
for diacetyl. NIOSH recommends keeping the occupational exposure of
2,3-PD below a level comparable to the level recommended for diacetyl.
Because the limit of 2,3-PD is 9.3 ppb, this is the effective REL as a timeweighted average for up to 8 hours/day during a 40-hour work week.
NIOSH recommends a short-term exposure limit for 2,3-pentanedione of
31 parts per billion during a 15-minute period. This demonstrates that
NIOSH is using the Bradford Hill viewpoint of analogy for 2,3
pentanedione to limit occupational exposure.
The Bradford Hill viewpoints are used as a framework for analyzing causation. Dr Durrani
notes these viewpoints are widely accepted in the scientific community, a point that Givaudan
does not contest. The viewpoints are:
Consistency of the observed association
Strength of the observed association
Specificity of the observed association
Temporal relationship of the observed association
Biological gradient (exposure-response relationship)
Experimental evidence (from human populations)
Case 5:18-cv-04081-LTS-SHL Document 396 Filed 01/10/22 Page 10 of 22
Doc. 308-4 at 9 (emphasis in original). With regard to 2,3-HD, Dr. Durrani’s report
In 2017, the National Institute of Environmental Sciences investigated
airway injury due to diacetyl as well as 2,3 HD. As expected, diacetyl was
able to induce more airway injury than 2,3 HD when human airway
epithelium was exposed to similar concentrations of approximately 1000
ppm. Diacetyl was able to induce cell death in the 12 exposures compared
to none in the 6 exposures of 2,3 HD. Diacetyl caused histopathologic
changes at approximately twice the rate of 2,3 HD in ciliated and goblet
cells. The two chemicals were able to induce approximately similar rates
of cell atrophy and basal and suprabasal spongiosis. These results indicate,
that while diacetyl is more potent than 2,3 HD at equal concentrations, 2,3HD is still capable of causing disease in a dose dependent fashion.
Id. Dr. Durrani testified that he was not aware of any entity that had established exposure
standards for 2,3-HD. Doc. 308-5 at 12. He also testified that he was “not aware of a
safe level of exposure to 2,3-PD that is safe for humans.” Doc. 308-5 at 10. Dr. Durrani
does not have any opinions as to Thiele’s actual exposures at APC.
Dr. Durrani acknowledges that the causal relationship between 2,3-PD and 2,3HD exposure and FRBOS is dose-dependent, meaning someone is more likely to suffer
adverse consequences the higher the dose and the longer the exposure. While Dr. Durrani
testified there was no “safe” level of exposure, he does not cite any scientific literature
in support of that theory. Rather, he relies on the NIOSH REL for diacetyl that was used
to draw a comparative REL for 2,3-PD. As for 2,3-HD, he identifies no exposure limits.
Because Thiele’s alleged injury is dose-dependent, Dr. Durrani must identify levels of
exposure that are expected to cause Thiele’s alleged injury (BO or FRBOS) and whether
Thiele could have been exposed to such levels. See Bland, 538 F.3d at 898 (noting a
general causation expert must identify (1) what amount of exposure was capable of
causing the alleged injury and (2) what amount the plaintiff was actually or probably
There is simply too great of an analytical gap for Dr. Durrani to reliably conclude
that 2,3-PD and 2,3-HD can cause BO or FRBOS. Dr. Durrani has identified neither the
Case 5:18-cv-04081-LTS-SHL Document 396 Filed 01/10/22 Page 11 of 22
level of 2,3-PD and 2,3-HD that can cause BO or FRBOS nor Thiele’s level of exposure.
Thiele’s reliance on Herbst is unpersuasive, as it involved a different substance (diacetyl)
and lacks explanation as to why the expert’s opinion met the exposure requirements.
Additionally, Thiele’s argument that quantification is unnecessary fails to acknowledge
that what is necessary is a “threshold showing” that the plaintiff was exposed to levels
known to cause the type of injuries he suffered. See Mattis, 295 F.3d at 861. For
instance, the general causation expert in Mattis established that plaintiff has been exposed
to dangerous levels of organic solvents by using a vapor concentration test. Id. While
the expert could not determine plaintiff’s exact exposure level, his test showed that
solvent vapors accumulated rapidly at extreme concentrations, far in excess of safe
exposure levels. Id. The expert also testified that plaintiff’s exposure levels would have
been even higher than the levels in his test because of characteristics of the heated can of
Here, even if I accepted that Dr. Durrani had identified the NIOSH REL for 2,3PD as a safe exposure level (even though Dr. Durrani testified he was not aware of a safe
level of exposure to 2,3-PD), Dr. Durrani still cannot identify Thiele’s actual exposure
levels or the exposure levels for someone working in a similar position at APC. See
Doc. 308-5 at 5 (Q: “Do you have any knowledge or any opinions as to the level of [2,3PD] that Mr. Thiele was exposed to at anytime during his employment at American
Popcorn?” A. “. . . . I don’t know what levels he was exposed to.”); id. at 6 (Q: “Is it
also correct that you have no opinions that Mr. Thiele’s exposure to Diacetyl, [2,3-PD]
or [2,3-HD] at APC was substantial or harmful?” A: “That’s correct, because I haven’t
seen the levels or gone through any of those other evaluations I don’t have any opinion
on Mr. Thiele’s exposures.”). As to 2,3-HD, he offers no exposure standards generally
or levels at APC. Id. at 11 (Q: “Are you offering opinions on the level of exposure to
[2,3-HD] that is sufficient to cause [BO] or any other lung disease?” A: “I haven’t
described any levels, no.”). Without knowing the levels of 2,3-PD or 2,3-HD that
workers at APC were exposed to during the time that Thiele worked there, Dr. Durrani
Case 5:18-cv-04081-LTS-SHL Document 396 Filed 01/10/22 Page 12 of 22
cannot offer a reliable opinion as to whether 2,3-PD and 2,3-HD are “capable of causing
injuries like that suffered by the plaintiff in persons subjected to the same level of
exposure as the plaintiff.” Mattis, 295 F.3d at 860. Without evidence concerning levels
of exposure at APC, Dr. Durrani’s general causation opinion relies on assumptions and
speculation and must be excluded as unreliable.
Robert Harrison, M.D. – Doc. 309
Givaudan seeks to exclude Dr. Harrison’s general causation opinion that diacetyl
is capable of causing lung disease for the same reason – Dr. Harrison does not know the
level of exposure to diacetyl that is likely to cause lung disease (i.e., the relationship
between the dose and the response) or the nature and amount of Thiele’s alleged exposure
to diacetyl. Givaudan argues that Dr. Harrison’s attempt to fill this fatal flaw in his
opinion with unsupported, speculative statements about “substantial” and “analogous”
exposures makes his opinion unreliable.
With regard to the level of exposure to diacetyl that is capable of causing lung
disease, Givaudan argues Dr. Harrison makes contradictory statements that there is no
level below which exposure to diacetyl is safe,6 but that 5 parts per billion averaged over
an eight-hour day and 25 parts per billion short-term, as established by the NIOSH REL,
are the levels at which diacetyl is capable of causing harm. Givaudan characterizes Dr.
Harrison’s opinion as a moving target that is inconsistent and unreliable. It notes that
courts often exclude dose-response relationship opinions that are based on regulatory
With regard to Thiele’s level of exposure, Givaudan argues that Dr. Harrison
offers only speculation that Thiele may have been exposed to a “hazardous” level or
levels that were “quite high” and offers no scientific testing, measurement or analysis in
Dr. Harrison testified to this effect in his deposition in Downs, but not in his deposition for this
case. See Doc. 309-9 at 6.
Case 5:18-cv-04081-LTS-SHL Document 396 Filed 01/10/22 Page 13 of 22
support. It contends Dr. Harrison’s characterization of Thiele’s exposure as “substantial
and analogous” is insufficient because the “substantial” aspect relies on the quantity of
finished flavors purchased by APC and is based on speculation rather than scientific
methodology. The “analogous” aspect relies on exposures measured at APC in 2001 and
2002, two years before Thiele began working there in 2004. Givaudan also notes (1) that
Thiele also wore a respirator more frequently than the workers who participated in the
NIOSH study in 2002 and (2) Dr. Harrison makes no analogy to any other worker at
APC and offers no analysis regarding the conditions at APC in 2004 compared to 2001
and 2002. In addition, Dr. Harrison relies on diacetyl levels at other popcorn facilities
but offers no analysis or discussion about how exposures at other popcorn plants were
analogous to Thiele’s exposure at APC. Finally, Givaudan argues the report related to
NIOSH’s investigation at the Gilster-May Lee facility in Jasper, Missouri, is not
comparable because the levels of diacetyl at APC were “hundreds of times lower than
the Jasper plant.”
Thiele argues that Daubert does not require a medical expert to quantify either the
level of exposure that is harmful or his actual level of exposure. He notes that Dr.
Harrison’s general causation opinion was deemed admissible in Herbst and that Givaudan
takes issue with Dr. Harrison’s conclusions rather than attacking his methodology, which
relies on the Bradford Hill viewpoints. Thiele also points out that Dr. Harrison has
opined that studies have not shown a level below which diacetyl does not cause lung
disease and cites NIOSH investigations into other microwave popcorn workers
performing similar tasks.
The Downs court considered similar arguments and excluded Dr. Harrison’s
opinion as unreliable. The court reasoned that Dr. Harrison failed to specify what level
of exposure to diacetyl will cause lung disease and declined to accept the NIOSH REL as
a reliable threshold to determine level of exposure that would be harmful. Downs et al.,
1:18-cv33, Doc. 468 at 14. With regard to Dr. Harrison’s methodology, the court
observed that Dr. Harrison relied on records of the defendant’s sales of butter flavoring
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products to the plant during plaintiffs’ employment and plaintiffs’ statements about their
work schedules and job duties. Dr. Harrison also applied quantitative air sampling data
of the harmful level of diacetyl in the air of the mixing room at another ConAgra plant
to conclude that plaintiffs’ exposure at the ConAgra plant where they worked was
“substantial and analogous.” Id. at 14.
The court found that Dr. Harrison failed to account for similarities and differences
between the two plants, such as when they were built, their ventilation systems, how
many air exchanges occurred in the mixing rooms at the respective plants or anything
else related to the specifics of the industrial hygiene systems at the plants. Id. at 15. The
court further found Dr. Harrison’s use of air sampling data from a different plant to be
problematic because it was an assumption not based in science.
sampling data collected by NIOSH from the mixing room at plaintiffs’ plant in 2001
(when plaintiffs were employed there) revealed that the levels of diacetyl in the mixing
room were below the level of detection and much lower than the levels measured at the
ConAgra plant Dr. Harrison relied on. Another sampling from the plant from February
2005 to February 2007 (when plaintiff Huntley worked there) showed that the level of
diacetyl was more than ten times lower than that detected at the plant Dr. Harrison relied
on during the same time period. The court concluded that Dr. Harrison’s reliance on
data from another plant while ignoring data collected from the plant where plaintiffs
worked during their periods of employment undermined the reliability of his
methodology. Id. at 17. As such, the court excluded Dr. Harrison’s opinion.
As discussed in the previous section, the relevant questions are whether Dr.
Harrison has (1) identified the level of exposure capable of causing harm and (2) made a
“threshold showing” that Thiele “was exposed to toxic levels known to cause the type of
injuries he . . . suffered.” See Mattis, 295 F.3d at 860-61; see also Bonner, 259 F.3d at
931 (“It is sufficient for a plaintiff to prove that she was exposed to a quantity of the
toxin that ‘exceeded safe levels.’”). Dr. Harrison does not identify a level of exposure
to diacetyl that is capable of causing lung disease in his report. In his deposition, he
Case 5:18-cv-04081-LTS-SHL Document 396 Filed 01/10/22 Page 15 of 22
explained that “if you go above five parts per billion, your risk is going to start to increase
at a level that is unacceptable because of the seriousness of this, the harm that can result.”
Doc. 309-5 at 13. He added that an exposure of five parts per billion (the NIOSH REL)
creates a significant risk of lung disease. Id.
Givaudan criticizes five parts per billion as an acceptable “threshold” identified
by Dr. Harrison for two reasons. First, it argues Dr. Harrison has been inconsistent in
his testimony in various other cases about the level of diacetyl exposure that poses a
significant risk of respiratory harm. See Doc. 317 at 17 (citing Dr. Harrison’s deposition
testimony from other cases in which he offers seemingly inconsistent testimony about the
level of exposure that can cause lung disease). Second, Givaudan notes that five parts
per billion is a regulatory standard and, as such, is conservative and establishes a level
below which no individual would be likely to suffer negative health effects. See Glastetter
v. Novartis Pharms. Corp., 252 F.3d 986, 991 (8th Cir. 2001) (“The methodology
employed by a government agency ‘results from the preventive perspective that agencies
adopt in order to reduce public exposure to harmful substances.’”) (quoting Hollander v.
Sandoz Pharms. Corp., 95 F. Supp. 2d 1230, 1234 n.9 (W.D. Okla. 2000)); Junk v.
Terminix Intern. Co. Ltd. P’ship, 594 F. Supp. 2d 1062, 1071 (S.D. Iowa 2008)
(“government agency regulatory standards are irrelevant to Junk’s burden of proof in a
toxic tort cause of action because of the agency’s ‘preventative perspective[.]’”), aff’d,
628 F.3d 439 (8th Cir. 2010).
Givaudan’s first argument is an issue for cross-examination, not exclusion.
Givaudan has not identified any inconsistencies in Dr. Harrison’s report or deposition
testimony in this case. To the extent his opinion conflicts with opinions he has made in
other cases, Givaudan can address those differences through cross-examination. As to
its second argument, the Eighth Circuit has explained:
Regulatory standards express risk assessments that are designed to protect
public health. “[A] regulatory standard, rather than being a measure of
causation, is a public-health exposure level that an agency determines
pursuant to statutory standards.” Sutera v. Perrier Grp. of Am. Inc., 986
Case 5:18-cv-04081-LTS-SHL Document 396 Filed 01/10/22 Page 16 of 22
F. Supp. 655, 664 (D. Mass. 1997) (citation omitted). Thus, a legislature
or regulatory agency may set standards – permissible or mandatory –
“without having precise data on the question of how much harm, or what
kind of harm, some specific amount of that substance might reasonably be
expected to cause to . . . an ordinary person.” Wright, 91 F.3d at 1107.
Kirk v. Schaeffler Group USA, Inc., 887 F.3d 376, 392 (8th Cir. 2018).7 I need not
resolve whether an expert may rely on a regulatory standard to establish a level of
exposure that is capable of causing harm because, even if I accept the NIOSH REL as a
reliable threshold, Dr. Harrison fails to identify any level of diacetyl to which Thiele was
Dr. Harrison concluded Thiele’s exposure to flavorings containing diacetyl was
“substantial and analogous to other occupational exposures to flavorings resulting in lung
disease.” Doc. 309-2 at 36. Similar to his opinion in Downs, he considered the amount
of flavorings containing diacetyl and other harmful diketones that were purchased by
APC (including 466,476 pounds from Givaudan) during the seven years Thiele worked
at APC. He also considered Thiele’s job duties, when he reported the onset of relevant
symptoms, some lung function measurements during his employment, when Thiele wore
a respirator, the 2004 NIOSH study results from APC (based on air sampling from 2001
and 2002), including the measurements in the mixing room and elsewhere in the factory,
In Kirk, the court found that the expert testified to “extensive TCE contamination in the Silver
Creek community and the many ways Kirk was exposed to that contamination for many years.”
Id. at 391. The plaintiff did not rely solely on regulatory standards to establish general causation
but such standards were considered probative evidence to be compared to the concentrations of
TCE found in Silver Creek wells in addressing the levels of TCE contamination to which
residents were exposed. Id.
The requirement that a general causation expert identify the level of exposure differs from
specific causation, which addresses whether the toxin actually caused the plaintiff’s injury. In
order for a general causation expert to opine that a toxin is capable of causing injury in the
general population, he or she must identify the level to which the plaintiff was exposed in order
to evaluate whether that level is capable of causing harm. See, e.g., Bonner, 259 F.3d at 928.
Thus, an expert cannot opine as to general causation in a toxic tort case without information as
to the relevant exposure and the standard by which to assess its harmfulness.
Case 5:18-cv-04081-LTS-SHL Document 396 Filed 01/10/22 Page 17 of 22
and NIOSH studies related to whether powdered flavorings can be inhaled. Doc. 309-2
at 36-38. He concluded:
The manner of Mr. Thiele’s exposure to the heated diketone-containing
flavorings at APC, his proximity to these heated flavorings, the large
amounts of these flavorings used at APC during his employment, and the
frequency and length of his exposures are all consistent with other flavoring
workers who have developed lung disease caused by their occupational
exposures to the same or similar food flavorings.
Id. When asked about his opinion as to Thiele’s actual exposure levels, Dr. Harrison
testified in his deposition, “when I looked at the study that NIOSH did at APC and the
measurements in the mixing room and elsewhere in the factory, the levels there were
quite high and I think hazardous, and as I outlined in my opinion, likely exposed Mr.
Thiele to harmful levels of diacetyl.” Doc. 309-5 at 6; see also id. at 10 (“Mr. Thiele’s
exposure to diacetyl at APC was very much like exposure to other workers who developed
lung disease from exposure to diacetyl in popcorn plants as well as many other types of
facilities that use diacetyl and workers were exposed, and that is shown by the history
that he gave.”).
While Dr. Harrison’s opinion is based primarily on air sampling data from APC,
rather than analogizing it to another facility as he did in Downs, his opinion still relies
on speculation and fails to account for changes at the facility that could have reduced
Thiele’s exposure. Dr. Harrison’s opinion as to Thiele’s exposure level is based on the
NIOSH air sampling measurements from 2001 and 2002. Therefore, he speculates that
the measurements were the same when Thiele began working at APC in 2004. He failed
to account for potential mitigating circumstances – including whether APC had made any
changes to the mixing room between 2002 and 2004 – and failed to account for known
mitigating circumstances, such as the use of air-supplied respirators. See Doc. 309-5 at
13. Dr. Harrison admitted that the 6 workers (out of 13) at APC who had been identified
by NIOSH as having abnormal lung function and who had any experience as mixers wore
respirators less frequently than Thiele.
Id. at 13-14 (noting the median reported
Case 5:18-cv-04081-LTS-SHL Document 396 Filed 01/10/22 Page 18 of 22
percentage was 20 percent for all activities except pouring other ingredients into tanks in
the mixing room, where the median reported percentage was 50 percent). Dr. Harrison
also testified, “[l]ooks like possibly by the time Mr. Thiele started working in 2004 there
was a more rigorous respiratory protection program.” Id. at 14.
To the extent Dr. Harrison attempts to analogize Thiele’s exposure to exposures
faced by workers at other popcorn plants, those opinions are also speculative. Dr.
Harrison testified, “Mr. Thiele’s exposure to diacetyl at APC was very much like
exposure to other workers who developed lung disease from exposure to diacetyl in
popcorn plants as well as many other types of facilities that use diacetyl and workers
were exposed, and that is shown by the history that he gave. We just talked about in his
deposition testimony the NIOSH study at APC.” Id. at 10. Dr. Harrison clarified that
his second opinion in his report “means that Mr. Thiele was probably in harm’s way
when he was working at APC.” Id.
Dr. Harrison’s analogy to other popcorn plants to conclude that Thiele’s exposure
was “hazardous” is unreliable for the reasons described in Downs and for other reasons
specific to this case. When asked about the other popcorn plants he relied on, Dr.
Harrison cited the NIOSH studies at Gilster-Mary Lee and the Marion, Ohio, ConAgra
plant, as discussed in Downs. Those studies were performed in 2001 and 2004. Dr.
Harrison could not identify any comparative analysis in his report between Thiele’s
exposure at APC and the measures of diacetyl in other popcorn plants beyond citing the
NIOSH reports. See id. In other words, his opinion appears to be that because a
“hazardous” level of diacetyl was found in other popcorn plants, it must have also been
present at APC. This methodology is speculative and unreliable. First, NIOSH found
that the average diacetyl concentration measured in the mixing room at APC in 2001 and
2002 was hundreds of times lower than NIOSH had measured at other popcorn plants.
Id. at 16, 21. Second, it fails to take into account any differences between the three
facilities. Third, NIOSH made recommendations to APC that would reduce exposure to
Case 5:18-cv-04081-LTS-SHL Document 396 Filed 01/10/22 Page 19 of 22
diacetyl, but Dr. Harrison did not know whether APC implemented any of those
recommendations. Id. at 17.
While the Eighth Circuit standards do not require an expert to quantify the amount
to which Thiele was exposed in order to demonstrate that he was exposed to a toxic level
of diacetyl,9 Dr. Harrison’s opinion presents too great of an analytical gap in light of the
data he relies on. Dr. Harrison relies on the NIOSH measurements from 2001 and 2002
and peak exposures in mixing rooms at various popcorn plants (without accounting for
use of a respirator). See Doc. 309-5 at 6. He acknowledged that with a powered air
purifying respirator (PAPR), Thiele would not have been breathing any of the air in the
mixing room, but instead the fresh air that was pumped into his mask. Id. at 8; see also
id. at 20 (explaining a PAPR provides a protection factor of a hundred (if used properly)
meaning that whatever the air concentration is on the outside should be reduced by a
hundred fold in the air that someone is breathing on the inside). He also acknowledged
that Thiele testified that he was given a PAPR. Id.
Additionally, Dr. Harrison admitted that the 6 APC workers with abnormal lung
function in 2001 and 2002 wore respirators less frequently than Thiele, and such
respirators were not PAPRs. Dr. Harrison admitted that the levels of diacetyl in the
mixing room do not reflect the level of exposure to a person wearing a respirator. Id. at
14. Dr. Harrison testified to measure the level of exposure to a person wearing a
respirator, one would make certain calculations based on how protective the respirator
was. Id. at 14. There is no indication in the record that Dr. Harrison performed those
calculations to determine Thiele’s exposure to diacetyl rather than the level of diacetyl in
the mixing room. Id. at 20. Dr. Harrison also admitted he did not analyze any changes
APC may have implemented, including recommendations from NIOSH, between 2002
An expert must show plaintiff was exposed “to a quantity of the toxin that ‘exceeded safe
levels.’” Bonner, 259 F.3d at 931 (quoting Bednar, 147 F.3d at 740). Dr. Harrison has
identified a safe level of diacetyl as anything below 5 parts per billion.
Case 5:18-cv-04081-LTS-SHL Document 396 Filed 01/10/22 Page 20 of 22
and 2004. Id. at 19. Finally, based on the readings at the Gilster-Mary Lee plant and
the substantially lower diacetyl readings at the APC plant, Dr. Harrison agreed that the
risk of developing lung disease in the APC mixing room would be lower than the risk at
the Gilster-Mary Lee plant. Id. at 21.
In summary, Dr. Harrison uses (1) outdated diacetyl measurements at APC, (2)
measurements from other popcorn plants and (3) measurements of general diacetyl levels
in the mixing room without accounting for (1) Thiele’s use of a respirator, (2) that the
levels of diacetyl at APC were a hundred times lower than other popcorn plants and (3)
any steps APC took after 2002 to address respiratory health of its workers. Dr. Harrison
did not use a “scientifically valid” method for opining that Thiele’s exposure exceeded a
safe level but instead relied on speculation and assumptions, resulting in an analytical gap
between the data and the opinion that is simply too great. For these reasons, I find his
general causation opinion is unreliable and must be excluded.
Motion for Summary Judgment
Givaudan argues it is entitled to summary judgment on all claims because, based
on its Daubert motions, Thiele has no admissible evidence that the ingredients to which
he claims exposure are capable of causing the injury he claims to have suffered. I agree.
Thiele’s claims require proof of causation through expert testimony. See Bland, 538
F.3d at 899 (affirming district court’s decision to exclude expert testimony on causation
as well as defendants’ motion for summary judgment because plaintiff could not, as a
matter of law, establish causation without expert testimony); Ranes v. Adams Labs., Inc.,
778 N.W.2d 677, 688 (Iowa 2010) (noting a plaintiff must show general and specific
causation in a toxic tort case and that in proving both types of causation, “expert medical
and toxicological testimony is unquestionably required to assist the jury.”). Because I
have determined that Thiele’s expert opinions and testimony as to general causation must
be excluded under Rue 702 and Daubert, Thiele cannot demonstrate a genuine issue of
material fact regarding causation. Givaudan is entitled to summary judgment.
Case 5:18-cv-04081-LTS-SHL Document 396 Filed 01/10/22 Page 21 of 22
For the reasons stated herein,
Givaudan’s motion (Doc. 308) to exclude the testimony and opinions of Dr.
Durrani is granted.
Givaudan’s motion (Doc. 309) to exclude the testimony and opinions of Dr.
Harrison is granted.
Givaudan’s motion (Doc. 315) for summary judgment is granted.
All other pending motions (Docs. 311, 312, 313, 314, 345 and 387) are
denied as moot.
The trial of this case, scheduled to begin March 14, 2022, is canceled.
Because this order disposes of all remaining claims, this action is hereby
IT IS SO ORDERED.
DATED this 10th day of January, 2022.
Leonard T. Strand, Chief Judge
Case 5:18-cv-04081-LTS-SHL Document 396 Filed 01/10/22 Page 22 of 22
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