Document ID: s3://data.kl3m.ai/documents/govinfo/USCOURTS/USCOURTS-ca7-14-03448/USCOURTS-ca7-14-03448-0/pdf.json

Parties Involved:
C.W.
Appellant
E.W.
Appellant
Textron, Inc.
Appellee

Document Text:

In the 

United States Court of Appeals 

For the Seventh Circuit ____________________ 

No. 14-3448 

C.W. and E.W., by Guardians and Next Friends

ADELE A. WOOD and JASON A. WOOD, 

Plaintiffs-Appellants, 

v.

TEXTRON, INC., 

Defendant-Appellee. 

____________________ 

Appeal from the United States District Court for the 

Northern District of Indiana, South Bend Division. 

No. 3:10 CV 87 — Philip P. Simon, Chief Judge. 

____________________ 

ARGUED MAY 18, 2015 — DECIDED AUGUST 26, 2015 

____________________ 

Before KANNE and SYKES, Circuit Judges, and Ellis, District 

Judge.

*

KANNE, Circuit Judge. Government regulators and scientists agree: exposure to vinyl chloride poses serious health 

 

*The Honorable Sara L. Ellis, of the United States District Court for the 

Northern District of Illinois, sitting by designation. 

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risks to humans. Vinyl chloride is a known carcinogen, mutagen, and genotoxin.1 But in what quantity and for how 

long must a human—in this case, two infant children—be 

exposed to vinyl chloride before those health risks materialize? The experts for C.W. and E.W., the minor children of Jason and Adele Wood, attempted to answer these difficult 

questions in this toxic-tort case. 

Unfortunately for the Woods, their attempts fell short. 

The district court excluded each of the appellants’ experts, 

observing they did not use reliable bases to support their 

opinions. Having excluded the appellants’ experts, the district court then granted summary judgment in favor of Textron. It found that, without the experts’ opinions, the appellants could not prove general and specific causation—

required elements under Indiana law in a toxic-tort case. 

Although we disagree with the district court’s rationale regarding causation, we nevertheless affirm. 

I. BACKGROUND

A. Preliminary History 

Textron began operations at its fastener manufacturing 

plant in Rochester, Indiana, in 1954. The Torx plant, as it 

came to be known, proved to be successful; it remained in 

operation through 2006. During its operations, however, the 

 

1 For the sake of clarity (primarily our own), we define scientific terms as 

the need arises. This occasion presents such a need. In reverse order: a 

genotoxin is a poisonous substance that damages DNA; a mutagen is 

something that is capable of causing mutations to DNA; and a carcinogen is something that causes cancer. MedicineNet.com Home Page, available at search.medicinenet.com (last visited Aug. 5, 2015). 

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No. 14-3448 3

plant released vinyl chloride—a toxic gas. That vinyl chloride eventually seeped into the ground water, contaminating 

nearby residential wells. 

One of those wells belonged to the Woods. Both Textron 

and the Indiana Department of Environmental Management 

performed testing on the Woods’ well. Their tests revealed 

varying levels of vinyl chloride—from 5.00 and 8.40 parts 

per billion to 8.60 and 9.00 parts per billion.2

Once the Woods learned that this toxic substance had 

contaminated their well, they understandably left immediately. Jason and Adele believed the health risks to their children were simply too high to remain at the Rochester house. 

But in the Woods’ opinion, there was more at stake than the 

future risk of cancer; there was the present risk of illness. 

While living at the Rochester house, C.W. and E.W. experienced gastrointestinal issues (vomiting, bloody stools), immunological issues, and neurological issues. 

The Woods adopted their son, C.W., when he was eleven 

weeks old. He came home on May 11, 2007. The Woods 

adopted their daughter, E.W., when she was eleven days old. 

She came home on April 25, 2008. Both children were 

younger than two years old when the entire family left the 

Rochester house in November 2008. Their illnesses coincided 

with their time spent in that house. 

After the Woods moved from that house, C.W.’s and 

E.W.’s health improved. But the parents’ concerns did not 

abate. Fearful that vinyl chloride caused C.W.’s and E.W.’s 

 

2 The appellants’ experts later estimated that C.W. and E.W. ingested 

water contaminated by vinyl chloride at 3 parts per billion. 

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conditions (and mindful of the known cancer risks), Jason 

and Adele sued Textron on behalf of their children in Fulton 

County Circuit Court. There, they advanced a three-count 

complaint, alleging negligence, negligence per se, and negligent infliction of emotional distress.3 The crux of these Indiana tort-law claims was that Textron exposed C.W. and E.W. 

to vinyl chloride, which caused their illnesses and substantially increased their risk of cancer and other adverse health 

effects. Just one week after the filing of the complaint, Textron successfully removed the case to federal court. 28 U.S.C. 

§§ 1332, 1441, 1446. The appellants then filed a Second 

Amended Complaint, this time in federal court, to add a 

fourth count for willful and wanton misconduct. 

The case proceeded through discovery and the marshaling of experts until, nearly four years after the appellants 

filed their original complaint, Textron filed a motion in 

limine to exclude the appellants’ three expert witnesses. As 

we noted above, that motion was successful; the district 

court granted it in its entirety. The district court then found 

that, without the experts, the appellants could not prove 

general or specific causation. It granted summary judgment 

in favor of Textron on all of the appellants’ claims. 

Before we turn our attention to the experts, we note that 

there are a number of contested facts that are not at issue in 

this appeal. For example, this appeal is not about whether, or 

with what frequency, Jason and Adele used bottled instead 

of tap water to make formula for their infant children. Nor is 

 

3 In their Second Amended Complaint, the appellants added a fourth 

count for willful and wanton misconduct. 

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this appeal about whether Jason and Adele’s reverseosmosis-water-filtration system sufficiently guarded the 

children against unacceptable levels of vinyl chloride. 

Instead, this appeal is about whether the district court 

abused its discretion in excluding the appellants’ experts 

based on the reliability of their methodology, and if it did not 

abuse its discretion, whether we should affirm its grant of 

summary judgment in favor of Textron. See Anderson v. Liberty Lobby, Inc., 477 U.S. 242, 248 (1986) (“Only disputes over 

facts that might affect the outcome of the suit under governing law will properly preclude the entry of summary judgment.”). 

B. The Experts 

Because our jurisdiction is based on diversity of citizenship, we apply federal procedural law and state substantive 

law. Allen v. Cedar Real Estate Grp., LLP, 236 F.3d 374, 380 (7th 

Cir. 2001) (citing Erie R.R. v. Tompkins, 304 U.S. 64, 78 (1938)). 

The parties do not dispute that Indiana substantive law applies here. To prove their toxic-tort claims under Indiana law, 

the appellants needed to present evidence of general and 

specific causation. 7-Eleven, Inc. v. Bowens, 857 N.E.2d 382, 

389 (Ind. Ct. App. 2006). General causation examines whether the substance—in this case, vinyl chloride—“had the capacity to cause the harm alleged[.]” Id. (emphasis added). 

Specific causation, by contrast, examines whether the substance did, in fact, cause the harm alleged. Id. (emphasis 

added). To satisfy this bifurcated burden, the plaintiffs offered the testimony of three experts: (1) Dr. James G. 

Dahlgren; (2) Dr. Vera S. Byers; and (3) Dr. Jill E. RyerPowder. 

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Both parties agree that these experts are well-qualified. 

So we can set that issue to the side. The dispute before us 

concerns the reliability of the methodology they employed in 

generating their expert opinions. The following section highlights their methodology as well as the district court’s rationale in rejecting it. We begin with Dr. Dahlgren. 

1. Dr. James G. Dahlgren 

Dr. Dahlgren offered opinions on both general and specific causation, testifying that, in his judgment, vinyl chloride can cause and did cause the children’s illnesses. He also 

opined that it is highly likely that both children will develop 

cancer at some point in the future. He based these opinions 

on a differential etiology4 and the fact that levels of vinyl 

chloride detected in the appellants’ water supply exceeded 

the regulatory levels set by the United States Environmental 

Protection Agency (“EPA”) and the Indiana Department of 

Environmental Management, among other government 

agencies. Dr. Dahlgren also based his opinions on timing, or 

in his words, “temporality.” In his view, the fact that the appellants’ symptoms began after exposure to vinyl chloride 

 

4 “Etiology is the study of causation.” Myers v. Ill. Cent. R.R. Co., 629 F.3d 

639, 644 (7th Cir. 2010) (citations omitted). A differential etiology is a 

process-of-elimination approach to determining a subject’s cause of injury. Under this method, an expert “considers all relevant potential causes 

of the symptoms and then eliminates alternative causes.” Federal Judicial 

Center, Reference Manual on Scientific Evidence 214 (1994). Although the 

parties and the district court below refer to this method as a “differential 

diagnosis,” that term is really a misnomer. A “diagnosis” is concerned 

only about naming the condition or ailment, not establishing its cause. 

Id.; see also Happel v. Walmart Stores, Inc., 602 F.3d 820, 825 n.7 (7th Cir. 

2010). 

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No. 14-3448 7

and lessened after removal helps demonstrate that vinyl 

chloride is the cause. 

As for Dr. Dahlgren’s differential etiology, it is largely 

based on the findings (or lack thereof) of other doctors who 

have examined C.W. and E.W. To be sure, Dr. Dahlgren conducted physical examinations of both C.W. and E.W. He also 

reviewed their medical records. But his differential etiology 

is silent on these matters. According to Dr. Dahlgren, “[t]he 

scientific studies ... demonstrate that damage to the immune 

system and the nervous system are known to be caused by 

[vinyl chloride] exposure. The thorough evaluations by the childrens’ [sic] doctors have not found an alternative explanation ... .” 

(emphasis added). 

Thus, to accept Dr. Dahlgren’s approach to differential 

etiology, one must accept both the scientific studies upon 

which Dr. Dahlgren relied and the care taken by the doctors 

who examined C.W. and E.W. One must also accept that vinyl chloride should be ruled in as a possible cause at all—a 

point we address below. 

The district court found Dr. Dahlgren’s methodology to 

be unreliable. Citing Cunningham v. Masterwear Corp., 569 

F.3d 673, 674–75 (7th Cir. 2009), it first found that Dr. 

Dahlgren could not rely on regulatory exceedances to 

demonstrate causation. Second, the district court found that 

Dr. Dahlgren failed to connect the dots between the scientific 

studies that he analyzed and the opinions that he offered. 

This is a Joiner problem. In Gen. Elec. v. Joiner, 522 U.S. 136, 

138 (1997), the Supreme Court decided to apply the abuse of 

discretion standard in reviewing the admission or exclusion 

of expert testimony. Affirming the district court’s exclusion 

of the experts there, the Court held that “nothing in either 

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Daubert or the Federal Rules of Evidence requires a district 

court to admit opinion evidence which is connected to existing data only by the ipse dixit of the expert. A court may conclude that there is simply too great an analytical gap between the data and the opinion proffered.” Id. at 146 (citations omitted). 

In the case before us, the district judge found fault in the 

studies that Dr. Dahlgren relied upon. “These articles ... fail 

to establish that [vinyl chloride] at the dose and duration 

present in this case could cause the problems that the 

[p]laintiffs have experienced or claim that they are likely to 

experience.” C.W. v. Textron, 2014 U.S. Dist. LEXIS 34938, at 

*53 (N.D. Ind. Mar. 17, 2014) (“Textron I”). The district judge 

then rejected Dr. Dahlgren’s efforts to apply those studies to 

this case. Id. at *45 (“The problem again, however, is that ... 

Dahlgren fails to bridge [the] gap by explaining how he is 

able to extrapolate” from those studies). 

2. Dr. Vera S. Byers 

Like Dr. Dahlgren, Dr. Byers also offered opinions on 

both general and specific causation. In her view, exposure to 

vinyl chloride can cause and did cause the children’s illnesses. 

She traced the children’s exposure to vinyl chloride to their 

ingestion of contaminated drinking water, inhalation of vapors from bathing, and dermal contact. She then linked that 

exposure to their gastrointestinal and immune-system problems. “The GI problems suffered by both children,” Dr. 

Byers wrote, “are consistent with the adverse events associated with vinyl chloride exposure.” As for the appellants’ 

immune-system issues, she noted that C.W. and E.W. have a 

“very similar pattern of elevated ... immune complexes ... . 

Given that these two children are genetically unrelated, the 

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most probable cause of this acquired immune complex complement activation is the Vinyl Chloride exposure.” Dr. 

Byers admitted that she knew little about C.W.’s and E.W.’s 

family medical histories. She further opined that both children are now at a heightened risk level for developing cancer. 

Like Dr. Dahlgren, Dr. Byers based her opinion, in part, 

on a differential etiology. For E.W., Dr. Byers ruled in: 

 Congenital structural abnormalities 

 Infectious agents including viral 

 Degenerative 

 Neoplastic 

 Toxicity including allergies or in this case exposure 

to vinyl chloride 

 Metabolic disorders 

 Psycho-social issues 

She then ruled out each alternative explanation until siding 

with vinyl chloride as the specific cause.5 To buttress her 

conclusion, Dr. Byers also relied on timing. “Vinyl Chloride 

exposure is the most probable cause of [E.W.’s] acute symptoms[,]” she opined. “Both children suffered these symptoms, most seriously by [E.W.], and both childrens’ [sic] 

symptoms subsided when the exposure ceased.” 

Once again, to accept Dr. Byers’s approach, one must accept as relevant the scientific studies upon which Dr. Byers 

relied. One must also accept that vinyl chloride should be 

 

5 Dr. Byers’s report does not discuss a differential etiology for C.W. 

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ruled in as a possible cause in the first place. The district 

court accepted neither. It excluded Dr. Byers based on her 

attenuated studies and on her failure to adequately extrapolate from them. 

3. Dr. Jill E. Ryer-Powder 

That brings us to Dr. Ryer-Powder. In her initial report of 

August 17, 2011, she addressed the issue of general causation. Dr. Ryer-Powder claimed that the children’s exposure to 

vinyl chloride was “at levels sufficient to cause harm” during the applicable time period. She further claimed that this 

same level of exposure was “sufficient to present an unacceptable risk of cancer in the future.” Like Dr. Byers, she tied 

the appellants’ exposure to ingestion, inhalation, and dermal 

contact with vinyl chloride. 

For largely the same reasons the district court excluded 

the testimony of Doctors Dahlgren and Byers, the district 

court also excluded the testimony of Dr. Ryer-Powder. For 

example, Dr. Ryer-Powder relied on regulatory exceedances 

to formulate her opinion as to causation: “One means by 

which the health risks from exposures to chemicals can be 

assessed is by comparison to government standards and 

regulations.” She found that in this case, the Woods’ drinking water exceeded the standards set by relevant government agencies. So in her view, that meant vinyl chloride was 

within the realm of possible causes for the appellants’ injuries. 

Dr. Ryer-Powder also relied on attenuated studies concerning much higher exposure levels of vinyl chloride than 

the ones experienced here. As with Doctors Dahlgren and 

Byers, the district court found that she did not do the necesCase: 14-3448 Document: 29 Filed: 08/26/2015 Pages: 21
No. 14-3448 11

sary work of extrapolating from those studies to C.W. and 

E.W. In sum, the district court found that Dr. Ryer-Powder 

did not offer a reliable basis to support her proffered opinion. 

With this overview in mind, we turn to the merits. 

II. ANALYSIS

A. Principles of Law 

1. Admissibility of Expert Testimony 

Federal Rule of Evidence 702 and Daubert v. Merrell Dow 

Pharmaceuticals., Inc., 509 U.S. 579 (1993), govern the admission of expert testimony in federal courts, even when our jurisdiction rests on diversity. See Wallace v. McGlothan, 606 

F.3d 410, 419 (7th Cir. 2010) (holding “standards for admitting expert evidence” are “matters that fall on the procedural 

side of the Erie divide,” and are thus governed by federal 

law) (citations omitted). Daubert itself commenced as a state 

court action before it was removed to the Southern District 

of California on diversity grounds. 509 U.S. at 582. 

Rule 702 provides: 

A witness who is qualified as an expert by 

knowledge, skill, experience, training, or education 

may testify in the form of an opinion or otherwise 

if: (a) 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; (b) the testimony is based on sufficient facts or 

data; (c) the testimony is the product of reliable 

principles and methods; and (d) the expert has reliably applied the principles and methods to the facts 

of the case. 

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Fed. R. Evid. 702. Under this rule, expert testimony must not 

only assist the trier of fact. It must also demonstrate sufficient reliability—a key concern of the district court below. Id.

The district court is the gatekeeper of expert testimony.6

We stress that “the key to the gate is not the ultimate correctness of the expert’s conclusions. Instead, it is the soundness and care with which the expert arrived at her opinion[.]”Schultz v. Akzo Nobel Paints, LLC, 721 F.3d 426, 431 (7th 

Cir. 2013) (citations omitted). 

Daubert provides several guideposts for determining reliability. These guideposts examine (1) whether the scientific 

theory has been or can be tested; (2) whether the theory has 

been subjected to peer-review and/or academic publication; 

(3) whether the theory has a known rate of error; and (4) 

whether the theory is generally accepted in the relevant scientific community. Schultz v. Akzo Nobel Paints, LLC, 721 F.3d 

426, 431 (7th Cir. 2013) (citing Daubert, 509 U.S. at 593–94). 

Importantly, this list is neither exhaustive nor mandatory. 

Chapman v. Maytag Corp. (In re Chapman), 297 F.3d 682, 687 

(7th Cir. 2002). In some cases it may also be appropriate to 

examine, as the district court did here, whether there is “too 

great an analytical gap between the data and the opinion 

proffered.” Joiner, 522 U.S. at 146. Ultimately, reliability is 

determined on a case-by-case basis. Ervin v. Johnson & Johnson, 492 F.3d 901, 904 (7th Cir. 2007). 

 

6 We stress that “the key to the gate is not the ultimate correctness of the 

expert’s conclusions. Instead, it is the soundness and care with which the 

expert arrived at her opinion[.]”Schultz v. Akzo Nobel Paints, LLC, 721 

F.3d 426, 431 (7th Cir. 2013) (citations omitted). 

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No. 14-3448 13

2. Standard of Review 

We employ a two-step standard of review in cases challenging a district court’s admission or exclusion of the testimony of an expert. First, we review de novo a district court’s 

application of the Daubert framework. United States v. Brumley, 217 F.3d 905, 911 (7th Cir. 2000). If the district court 

properly adhered to the Daubert framework, then we review 

its decision to exclude (or not to exclude) expert testimony 

for abuse of discretion. Id. (citing Walker v. Soo Line R.R. Co., 

208 F.3d 581, 590 (7th Cir. 2000)). 

B. The District Court’s Adherence to Daubert 

The district court properly adhered to the Daubert 

framework. The court began its exhaustive review of the appellants’ three proposed experts by accurately outlining the 

Daubert framework. Textron I, 2014 U.S. Dist. LEXIS 34938, at 

*6–10. During that outline, the court aptly noted the need for 

flexibility in applying Daubert, particularly given “the various types of potentially appropriate expert testimony.” Id. at 

*9 (citing Deputy v. Lehman Bros., Inc., 345 F.3d 494, 505 (7th 

Cir. 2003)) (additional citations omitted). 

The court then conducted an in-depth review of the relevant studies that the experts relied upon to generate their 

differential etiology. Textron, supra, at *11–53. This careful 

approach stands in stark contrast to other cases where we 

concluded that courts did not adhere to the Daubert framework. See, e.g., Metavante Corp. v. Emigrant Sav. Bank, 619 F.3d 

748, 760 (7th Cir. 2010) (declining to apply abuse of discretion standard where the district court’s one-sentence expert 

determination did not satisfy Daubert); Naeem v. McKesson 

Drug Co., 444 F.3d 593, 608 (7th Cir. 2006) (same). And on a 

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much larger scale, the district court’s approach follows the 

same path blazed by the Supreme Court in Joiner. 522 U.S. at 

145 (reviewing four epidemiological studies advanced by the 

respondent in support of the experts’ conclusions). 

According to the appellants, however, the district court 

imposed an unachievable requirement that “published literature exist on the topic of vinyl chloride poisoning in small 

children.” It did so, allegedly, despite the Supreme Court’s 

admonition that “[p]ublication (which is but one element of 

peer review) is not a sine qua non of admissibility.” Daubert, 

509 U.S. at 593. The argument that the district court erroneously inflated the importance of publications is unavailing. 

The appellants misread the district court’s decision. The 

district court imposed no such requirement. Instead, it faulted the appellants’ experts for failing to adequately extrapolate from the studies they had. To be sure, the district court 

also rejected some of the studies as too attenuated from the 

appellants’ case. But its rejection of these studies is not tantamount to a requirement of absolute precision. Instead, its 

rejection is a recognition of an analytical gap too wide to be 

bridged. 

Take, for example, the rejected study that analyzed the 

carcinogenic effect of vinyl chloride on lab rats.7 Cesare Maltoni, et al., Carcinogenity Bioassays of Vinyl Chloride Monomer: 

A Model of Risk Assessment on an Experimental Basis, 41 Envtl. 

Health Persp. 3 (1981). This study found no statistically sig-

 

7 For the sake of economy, we pull two studies as a representative sample of the whole—one that deals with animals and one that deals with 

humans. 

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nificant increase in the number of tumors developed by rats 

that were fed 0.03 milligrams of vinyl chloride per kilogram 

of bodyweight, (0.03 mg/kg), of vinyl chloride per day (4 to 5 

days per week, for 59 weeks), over the control group of rats 

that were fed only olive oil. Id. at 16, 21. Remarkably, 0.03 

mg/kg is ten times higher than the amount the appellants 

allegedly ingested—Dr. Ryer-Powder estimates they ingested 0.003 mg/kg. And the rats ingested it over a period of 

time much longer, at least in rat years, than the children’s 

exposure here. Given these facts, Dr. Ryer-Powder’s conclusion that this study shows that C.W. and E.W. are now at an 

increased risk of developing cancer was an inferential leap 

that the district court was rightly unwilling to make. 

This second rejected study, which analyzed the effect of 

vinyl chloride on French workers, fares no better. See Steven 

J. Smith, et al., Molecular Epidemiology of p53 Protein Mutations 

in Workers Exposed to Vinyl Chloride, 147 Am. J. Epidemiology 

302 (1998). It drew from a group of adults over the course of 

five years. Id. at 302. Yet C.W. and E.W. were exposed to vinyl chloride for less than seventeen and seven months, respectively. As for the levels of exposure, the workers were 

divided into exposure groups with the average level set at 

3,735 parts per million. Id. at 304. That amount is over 1,000 

times greater than the 3 parts per billion to which the children were exposed. Nevertheless, Dr. Byers offered it in 

support of her opinion that the children are at an increased 

risk of developing cancer. 

In rejecting these studies and others like it, the district 

court properly exercised its role as gatekeeper under Daubert. And the district court acknowledged that studies need 

not be precisely analogous to meet the Daubert reliability 

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standard. Textron I, supra, at *53 (“I am mindful that an expert’s opinion does not have to be unequivocally supported 

by epidemiological studies in order to be admissible under 

Daubert.”) (internal quotations and citations omitted). Accordingly, it is entitled to deferential review in the second 

stage of our analysis. 

C. The District Court’s Exclusion of the Experts’ Testimony 

Under the second step in our analysis, we apply the 

abuse of discretion standard of review. Brumley, 217 F.3d at 

911. This standard demands that we “not disturb the district 

court’s findings unless they are manifestly erroneous.” Lapsley v. Xtek, Inc., 689 F.3d 802, 809 (7th Cir. 2012) (citations 

omitted). A deferential standard, it flows from the “wide latitude and discretion” that district courts enjoy when deciding 

whether to admit or exclude expert testimony. Ervin, 492 

F.3d at 904 (quoting Wintz by & Through Wintz v. Northrop 

Corp., 110 F.3d 508, 512 (7th Cir. 1997)). 

Here, the district court did not abuse its discretion in excluding the appellants’ experts. The district court’s primary 

concern, and ours on appeal, is the failure of the experts to 

connect the dots from the studies to the illnesses endured by 

the children. This is the Joiner problem to which we referred 

earlier. When a district court “conclude[s] that there is simply too great an analytical gap between the data and opinion 

proffered” such that the opinion amounts to nothing more 

than the ipse dixit of the expert, it is not an abuse of discretion under Daubert to exclude that testimony. Joiner, 522 U.S. 

at 146. That is what happened here. 

The appellants counter with a reasonable argument. They 

note that there are no studies available on the impact of viCase: 14-3448 Document: 29 Filed: 08/26/2015 Pages: 21
No. 14-3448 17

nyl chloride on children. These studies are unavailable because of the ethical and moral concerns of introducing toxins 

to children. This point is well taken and, we note, the district 

court recognized as much. Textron I, supra, at *44 (“[I]t’s 

wholly unsurprising that Dahlgren was unable to cite a 

study at the precise dose and duration that the ... children 

were subject to, and nothing in the case law says that he 

must do so.”). 

But there is a scientific end-around to make up for this 

dearth in literature. Scientists have developed computerbased models to extrapolate from animal data to human subjects, and from high doses to lower doses. Bernard D. 

Goldtsein & Mary Sue Henifin, Reference Guide on Toxicology

in Federal Manual on Scientific Evidence 646 (3d ed. 2011) 

(“The mathematical depiction of the process by which an external dose moves through various compartments in the 

body until it reaches the target organ is often called physiologically based pharmokinetics or toxicokinetics.”). Goldstein and Henifin recognize that “[a]dvances in computational toxicology” have facilitated this approach. Id. at 646–

47. The EPA recognizes this and other methods of extrapolation as valid approaches to bridging the gap between the 

studies and the general public. U.S. Envtl. Prot. Agency, Toxicological Review of Vinyl Chloride 37–63 (2000) (discussing 

methods to extrapolate to low doses and to humans, generally). The appellants’ experts do not mention or refer to this 

model of extrapolation. 

As for the district court’s rejection of the attenuated studies themselves, that too falls within the ambit of Joiner. See

522 U.S. at 144–45 (“The studies were so dissimilar to the 

facts presented in this litigation that it was not an abuse of 

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discretion for the District Court to have rejected the experts’ 

reliance on them.”). The district court’s decision fell within 

its wide scope of discretion, and we will not upset it here. 

The district court also found fault in the experts’ differential etiology because, in its view, the etiology was not reliable. We agree. Dr. Dahlgren’s differential etiology does not 

present the reliability that Daubert demands. An example is 

helpful here. After ruling in the alternative causes of “inheritance, allergy, infection or another poison,” Dr. Dahlgren 

then ruled them out because, in his view, these causes 

“would have been detected by [the appellants’] doctors and 

treated accordingly.” 

This approach is not the stuff of science. It is based on 

faith in his fellow physicians—nothing more. The district 

court did not abuse its discretion in rejecting it. As for Dr. 

Byers’s differential etiology, it showcases a rigor missing in 

Dr. Dahlgren’s. But it nevertheless contains a fatal flaw: ruling in vinyl chloride as a cause in the first place. Without the 

benefit of analogous studies and an acceptable method of 

extrapolation, Dr. Byers, like the other experts, is forced to 

take a leap of faith in pointing to vinyl chloride as having the 

capacity to cause the injuries (and risk of injury) to C.W. and 

E.W. The district court ably performed its gatekeeper role in 

shielding a jury from this leap. 

Dr. Ryer-Powder seeks a boost from government regulation. Recall her report: “One means by which the health risks 

from exposure to chemicals can be assessed is by comparison to government standards and regulation.” But exceedance of government regulation, as we’ve held before, does 

not by itself prove causation. See Cunningham, 569 F.3d at 675 

(rejecting this approach because the expert would have to 

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No. 14-3448 19

know “the specific dangers” that caused the regulatory 

agency “to pick the safe level it did”). The district court did 

not abuse its discretion in rejecting this methodology. To the 

extent the experts also based their opinions on the timing of 

C.W.’s and E.W.’s injuries, the district court properly rejected 

this methodology as well. Ervin, 492 F.3d at 904–05 (7th Cir. 

2007) (“The mere existence of a temporal relationship between taking a medication and the onset of symptoms does 

not show a sufficient causal relationship.”). 

In sum, the district court did not abuse its discretion in 

excluding the appellants’ experts. We now turn to the final 

question on appeal: whether that exclusion was fatal to the 

appellants’ toxic-tort case. 

D. Summary Judgment 

We review a district court’s grant of summary judgment 

de novo. Hanover Ins. Co. v. N. Bldg. Co., 751 F.3d 788, 791 (7th 

Cir. 2014). Summary judgment is appropriate where the admissible evidence reveals no genuine issue of any material 

fact. Fed. R. Civ. P. 56(c). 

Given the complex nature of this case, and considering 

the appellants make no argument that their case can survive 

without the excluded experts,8 this final issue can be resolved more simply. With no experts to prove causation—be 

it general or specific, see Bowens, 857 N.E.2d at 389—the ap-

 

8 Before the district court, the appellants’ argued that the opinions of 

their treating physicians, Doctors Claude Ruffalo and Jerrod Feldman, 

along with Textron’s expert, Dr. Thomas McHugh, were sufficient to establish causation to survive summary judgment. Textron II, supra, at *5–6. 

These arguments are not advanced here. 

Case: 14-3448 Document: 29 Filed: 08/26/2015 Pages: 21
20 No. 14-3448 

pellants cannot prove their toxic-tort case under Indiana law. 

Accordingly, we hold that summary judgment in this case 

was proper. 

Before concluding, however, we must part ways with the 

district court’s rationale in granting summary judgment. For 

we think the court unnecessarily foreclosed an issue better 

left open for future litigants in other cases. The district court 

held that differential etiology “cannot be used to support 

general causation.” C.W. v. Textron, 2014 U.S. Dist. LEXIS 

141593, at *11 (N.D. Ind. Oct. 3, 2014) (“Textron II”). It reiterated this holding in a footnote: “Differential [etiology] is 

admissible only insofar as it supports specific causation, 

which is secondary to general causation ... .” Id. at *12 n.3. 

We disagree with the district court’s categorical exclusion 

of differential etiology as a method to establish general causation. Indiana recognizes the important role that differential 

etiology plays in toxic-tort cases. Hannan v. Pest Control 

Servs., 734 N.E.2d 674, 682 (Ind. Ct. App. 2000). And there 

may be a case where a rigorous differential etiology is sufficient to help prove, if not prove altogether, both general and

specific causation.9 The Second Circuit already takes this ap-

 

9 The Federal Rules of Evidence contemplate using one piece of evidence 

to help prove multiple facts in issue. That is why, in appropriate circumstances, Rule 105 allows a district court to restrict the scope of evidence 

and instruct a jury accordingly. Fed. R. Evid. 105. For this reason, among 

others, at least one scholar believes differential etiology “should be admissible on general causation.” Edward J. Imwinkelreid, The Admissibility 

and Legal Sufficiency of Testimony About Differential Diagnosis (Etiology): Of 

Under–and Over–Estimations, 56 Baylor L. Rev. 391, 406 (2004) (“[A]n etiological opinion expressly addressing specific causation is also relevant to 

general causation; a plausible finding that a factor was the cause in a 

(continued...) 

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No. 14-3448 21

proach. See Ruggiero v. Warner-Lambert Co., 424 F.3d 249, 254 

(2d Cir. 2005) (“There may be instances where, because of 

the rigor of differential diagnosis performed, the expert’s 

training and experience, the type of illness or injury at issue, 

or some other ... circumstance, a differential diagnosis is sufficient to support an expert’s opinion in support of both general and specific causation.”). And we adopt it today. 

III. CONCLUSION

For the foregoing reasons, the district court properly applied the Daubert framework to the appellants’ experts. It did 

not abuse its discretion in excluding their testimony. Without expert testimony to prove general and specific causation, 

the appellants could not prove their case. Although we disagree with the district court that differential etiology can never be used to establish general causation, we nevertheless 

AFFIRM its final judgment. 

 

(...continued) 

specific case slightly strengthens the inference that the factor in question 

is capable of causing illness which the plaintiff developed.”). 

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