PRECEDENTIAL

UNITED STATES COURT OF APPEALS

FOR THE THIRD CIRCUIT

_____________

Nos. 15-3506, 15-3507, 15-3508, 15-3509, 15-3510, 

15-3511, 15-3512, 15-3513, 15-3514, 15-3515, 15-3564, 

15-3639, 15-3640, 15-3641, 15-3642, 15-3643, 15-3644, 

15-3645, 15-3646, 15-3647, 15-3648, 15-3649, 15-3650, 

15-3651, 15-3652, 15-3653, 15-3654, 15-3655, 15-3656, 

15-3657, 15-3658, 15-3659, 15-3660, 15-4075, 15-4076, 

15-4077, 15-4078, 16-1694, & 16-1965

_____________

MICHELLE MCMUNN, personal representative of the 

Estate of Eva Myers; 

CARA D. STEELE; YVONNE SUE ROBINSON; 

EDWARD J. MYERS; 

LEVI DANIEL STEELE; HAROLD ROBINSON, et al

 

v.

BABCOCK & WILCOX POWER GENERATION 

GROUP, INC.; 

B&W TECHNICAL SERVICES, INC., FKA B&W 

Nuclear Environmental 

Services, Inc.; ATLANTIC RICHFIELD COMPANY, 
2

predecessors-in-interest, 

successors-in-interest, subdivisions and subsidiaries; 

BABCOCK & WILCOX TECHNICAL SERVICES 

GROUP, INC.

Apollo Facility Plaintiffs, Appellants 

in Nos. 15-3506, 15-3507, 15-3508, 

15-3509, 15-3510, 15-3511, 15-3512, 

15-3513, 15-3514, 15-3515, 15-3564, 

15-4075, 15-4076, 15-4077, 15-4078, 

16-1964 and 16-1965

Babcock & Wilcox Power Generation 

Group, Inc. and Babcock & Wilcox 

Technical Services Group, Inc., Appellants 

in Nos. 15-3640, 15-3642, 15-3644, 

15-3646, 15-3648, 15-3650, 15-3652, 

15-3654,15-3656, 15-3658 and 15-3660

Atlantic Richfield Company, Appellant in 

Nos. 15-3639, 15-3641, 15-3643, 15-3645, 

15-3647, 15-3649, 15-3651, 15-3653, 

15-3655, 15-3657 and 15-3659

_____________

On Appeal from the United States District Court

for the Western District of Pennsylvania

District Court Nos. 2-10-cv-00143, 2-10-cv-00368, 

2-10-cv-00650, 2-10-cv-00728, 2-10-cv-00744, 

2-10-cv-00908, 2-10-cv-01736, 2-11-cv-00898, 
3

2-11-cv-01381, 2-12-cv-01221, 2-12-cv-01459, 

2-13-cv-00186, 2-13-cv-00704, 2-13-cv-01527, 

2-14-cv-00639, 2-15-cv-00844, 2-15-cv-01423

District Judge: The Honorable David S. Cercone

Argued November 10, 2016

Before: SMITH, Chief Judge, McKEE, and RESTREPO, 

Circuit Judges

(Filed: August 23, 2017)

Louis M. Bograd [ARGUED]

Motley Rice

3333 K Street, N.W.

Suite 450

Washington, DC 20007

Jonathan D. Orent

Motley Rice

321 South Main Street

P.O. Box 6067

Providence, RI 02904

Anne McGinness Kearse

Motley Rice

28 Bridgeside Boulevard

Mount Pleasant, SC 29464
4

David B. Rodes

Goldberg Persky & White P.C.

11 Stanwix Street

Suite 1800

Pittsburgh, PA 15222

Counsel for Appellants

Stephen B. Kinnaird

Paul Hastings LLP

875 15th Street, N.W.

Suite 1000

Washington, DC 20005

Peter C. Meier

John P. Phillips [ARGUED]

Sean D. Unger

Paul Hastings LLP

55 Second Street

24th Floor

San Francisco, CA 94105

Nancy G. Milburn [ARGUED]

Philip H. Curtis

Reuben S. Koolyk

Arnold & Porter LLP

399 Park Avenue

34th Floor

New York, NY 10022
5

Geoffrey J. Michael

Arnold & Porter LLP

601 Massachusetts Avenue, N.W.

Washington, DC 20001

Counsel for Appellees

_____________________________

OPINION OF THE COURT

_____________________________

SMITH, Chief Judge, joined by RESTREPO, Circuit 

Judge, who also joins in the Concurrence.

Plaintiffs assert that they developed cancer1after 

being exposed to excessive radiation emissions from the 

Nuclear Material and Equipment Company (“NUMEC”) 

facility in Apollo, Pennsylvania (the “Apollo facility”). 

Plaintiffs do not challenge the District Court’s 

conclusions that their common-law claims against 

 

1 For simplicity’s sake, we refer to the individuals 

diagnosed with cancer as “Plaintiffs” even though several 

of those individuals have died and the executors of those 

individuals’ estates have been substituted as plaintiffs. 
6

Defendants2 were preempted by the Price-Anderson Act 

and that only their Price-Anderson “public liability”

claims are at issue in this appeal. Although the PriceAnderson Act preempted Plaintiffs’ common-law 

negligence claims, Plaintiffs’ Price-Anderson public 

liability claims require Plaintiffs to prove versions of the 

traditional negligence elements—(1) duty, (2) breach, 

(3) causation, and (4) damages.

The District Court held that Defendants were 

entitled to summary judgment as a matter of law on the 

Price-Anderson claims because Plaintiffs failed to show 

that there was a genuine dispute of material fact as to 

elements of duty, breach, and damages. Plaintiffs 

appealed. We agree with the District Court: Plaintiffs 

are missing critical elements, and therefore their claims 

fail.

 

2 Defendants are Atlantic Richfield Company and 

Babcock & Wilcox Power Generation Group, Inc., 

Babcock & Wilcox Technical Services Group Inc., and 

B&W Technical Services Inc. Atlantic Richfield 

Company and Babcock & Wilcox Power Generation 

Group, Inc., were owners of the NUMEC facility at 

different points in time. See, e.g., JA1467 (stating that 

Atlantic Richfield bought the Apollo facility from 

NUMEC in 1967 and Babcock & Wilcox purchased the 

facility in 1971).
7

Accordingly, we will affirm the judgment of the 

District Court. 

BACKGROUND

I. THE PARTIES AND EMISSIONS

A. The Parties

Plaintiffs are more than seventy individuals3in a 

group of consolidated cases who claim that excessive 

radiation emitted by Defendants—more specifically, 

radiation from uranium effluent from the Apollo 

facility—caused them to develop various cancers. 

Almost all of the Plaintiffs lived near Apollo, 

Pennsylvania, for many years, including the 1960s, and 

almost all of the Plaintiffs were diagnosed with at least 

one form of cancer between 2007 and 2011.4 The 

 

3 At oral argument, even Plaintiffs’ counsel was unable to 

fix the exact number of plaintiffs. See Oral Arg. Tr. at 

4:6–19.

4 This period of time when most Plaintiffs were 

diagnosed with cancer may reflect that another group of 

individuals who developed cancer had previously sued 

Babcock & Wilcox and Atlantic Richfield Co. Their 

lawsuit apparently settled before trial. See Docket, Hall 

v. Babcock & Wilcox, No. 94-951 (W.D. Pa.); see also 
8

similarities among the Plaintiffs end there. By our count, 

Plaintiffs alleged that they suffered from more than a 

dozen different types of cancer.

5

 Plaintiffs were of 

widely varying ages at the times of their diagnoses—with 

at least one individual under 30 and at least five 

individuals over 80. See JA3460 (81); JA3478 (82); 

JA3479 (88); JA3482 (81); JA3485 (29); JA3491 (82). 

Many of the Plaintiffs had extensive smoking histories, 

and some had multiple cancer diagnoses over their 

lifetimes. See, e.g., JA3474 (“smoked about half a pack

per day for 40 years”); JA3463 (“diagnosed with breast

cancer in 1986 and then again in 2008 at the age of 67”). 

 

Hall v. Babcock & Wilcox, No. 94-951, 2007 WL 

1740852 (W.D. Pa. June 14, 2007). The diagnosis date 

range here may also reflect statute of limitations 

concerns. The statute of limitations is not an issue in this 

appeal. 

5 See, e.g., JA3447 (“Non Hodgkin’s Lymphoma”); 

JA3448 (“lung cancer”); JA3449 (“breast cancer”); 

JA3450 (“esophageal cancer”); JA3451 (“colorectal 

cancer”); JA3455 (“thyroid cancer”); JA3457 (“kidney 

cancer”); JA3458 (“endometrial cancer”); JA3459 

(“bladder cancer”); JA3465 (“melanoma”); JA3474 

(“prostate cancer”); JA3479 (“metastatic ovarian

cancer”); JA3485 (“squamous cell tumor of her pelvis”).
9

B. The Facility

The Apollo facility was a “warehouse style 

building that was not specifically constructed to house 

the complex manufacturing operation involving 

radioactive materials.” JA1427. As Plaintiffs 

emphasize, the Apollo facility was adjacent to a steel mill 

and “in the immediate neighborhood of residential 

areas.” JA1576. 

The Apollo facility operated from approximately 

1953 to 1983 with uranium fuel manufacture beginning 

in 1958 and decommissioning beginning in 1978. See 

JA1467; McMunn v. Babcock & Wilcox Power 

Generation Grp., 131 F. Supp. 3d 352, 356 (W.D. Pa. 

2015). 

The Atomic Energy Commission (“AEC”) was the 

federal regulatory body in charge of overseeing the 

Apollo facility. During the time that the Apollo facility 

operated, the Nuclear Regulatory Commission (“NRC”) 

became “the statutory successor to the Atomic Energy 

Commission.” In re TMI, 67 F.3d 1103, 1112 (3d Cir. 

1995). 

The Apollo facility emitted radiation as a 

necessary byproduct of manufacturing uranium fuel. 

Plaintiffs argue that that radiation was in excess of 

regulatory limits. The focus in this dispute is on 

radiation emitted from the stacks, vents, and fans on the 

Apollo facility’s roof.
10

C. Evidence of Excessive Emissions

Much of Plaintiffs’ evidence of excessive 

emissions indicates that emissions from the stacks or 

vents on the roof exceeded the maximum permissible 

concentration (“MPC”) for the facility. Plaintiffs do not 

contest that the relevant maximum permissible 

concentration is 8.8 disintegrations per minute per cubic 

meter (dpm/m3). See McMunn, 131 F. Supp. 3d at 373 

n.24; Pls.’ Br. 10; cf. JA3642.

As discussed below, under the applicable 

regulations, the maximum permissible concentration is 

determined at the boundary of the “unrestricted area.” 

Defendants argue that the boundary of the unrestricted 

area is the boundary of the roof, while Plaintiffs argue 

that any emissions from any part of the roof—including 

emission from any stack, vent, or fan—should be less 

than the maximum permissible concentration.

Plaintiffs point to evidence that they believe 

supports their position. In a June 5, 1964 letter, the 

Director of the Division of State and Licensee Relations 

of the AEC implied that the NUMEC had not shown that 

the roof was a restricted area: “[T]he roof area of the 

NUMEC facility is an unrestricted area unless access to 

this area is controlled from the radiation safety 

standpoint.” JA5314. Consistent with the 1964 letter 

implying that the entire roof may be unrestricted, 

Plaintiffs argue that NUMEC and AEC’s course of 

conduct shows that they both thought that stack 
11

emissions were a regulatory concern because NUMEC 

and AEC compared stack emissions to the maximum 

permissible concentration. For instance, in a 1967 report, 

a NUMEC employee wrote, “[T]he measured stack 

concentration frequently exceeds permissible levels.” 

JA5201. The AEC similarly expressed concern about 

releases from stacks, as though the regulations created 

limitations on the stacks. In a February 5, 1969 letter, the 

Director of the Division of Compliance of the AEC 

warned, “Based on your recorded data, the concentrations 

of radioactive material released from the facility through 

exhaust stacks to unrestricted areas exceed the limits 

specified in Appendix B, Table II of 10 CFR 20, contrary 

to 10 CFR 20.105(a), ‘Concentrations in effluents to 

unrestricted areas.’” JA4700. 

In addition to the evidence about emissions from 

the stacks or vents, Plaintiffs’ evidence of excessive 

emissions fits into one or more of the following three 

categories: (1) evidence that the monitoring of emissions 

was not completely comprehensive; (2) data that there 

was excessive radiation in the area surrounding the 

facility; and (3) data showing excessive radiation being 

released but seemingly only for specific, and short,
12

periods of time (such as when the facility’s incinerator 

was being used).6 

Plaintiffs marshaled a large number of documents 

that they alleged created a genuine issue of material fact. 

The highlights of Plaintiffs’ documents are below:

 In an April 20, 1964 letter, NUMEC 

Manager E.V. Barry wrote to Eber R. Price 

at the AEC that “average yearly 

concentrations at our property line” were 

being exceeded “when the winds are from 

the south quadrant” or in sections “when the 

winds are from the east quadrant.” JA5163. 

 

6 Our summary of Plaintiffs’ evidence mirrors Plaintiffs’ 

own summary presented at the conclusion of oral 

argument. When asked about “discharges measured at 

the roof edge,” Plaintiffs’ counsel (1) asserted that 

Defendants’ “roof edge monitoring . . . is remarkably 

incomplete”; (2) pointed to an April 20, 1964 letter 

(discussed below) in which NUMEC admitted that it 

sometimes exceeded permissible concentrations at the 

boundary of the roof; (3) highlighted the airborne 

concentrations of effluent when the plant’s incinerator 

was operating; and (4) noted “environmental monitors in 

the community.” Oral Arg. Tr. at 39:10–40:20.
13

 Data for part of the year 1966 shows a high 

of 41.5 dpm/m3and an average of 13.0 

dpm/m3. See JA5188. But, as Plaintiffs 

admit, the “high” refers to only one day. 

See Pls.’ Br. 47–48 (referring to “the same 

day” that the sampler gave its “highest 

reading”). Additionally, this data comes 

from a nearby building and not the roof of 

the Apollo facility. Compare JA5188, with

JA5189. 

 An August 18, 1967 internal memorandum 

about the Apollo facility’s incinerator states, 

“Ever since the incinerator has been in 

operation it has been a consistent source of 

airborne contamination causing an over 

exposure [sic] to the operators and air levels 

above the M.P.C. in and out of the plant.” 

JA4428.

 In a February 5, 1969 letter, the Director of 

the Division of Compliance of the AEC 

wrote, among other things, “Based on your 

recorded data, the concentrations of 

radioactive material released from the 

facility through exhaust stacks to 

unrestricted areas exceed the limits specified 

in Appendix B, Table II of 10 CFR 20, 

contrary to 10 CFR 20.105(a), 
14

‘Concentrations in effluents to unrestricted 

areas.’” JA4700. 

 A November 30, 1972 internal 

memorandum memorializing a phone call 

from the AEC states that the AEC 

commented that “NUMEC has been the 

worst offender of AEC regulations over the 

years,” that “[t]he AEC is strongly 

considering imposing civil penalties,” and 

mentions NUMEC was implementing 

corrective actions in, among other things, its 

“Liquid Waste Management Program,” and 

“Building Ventilation and Surveillance 

Program.” See JA4439–40. 

 In a February 12, 1974 letter, a NUMEC 

employee criticized the Apollo facility for 

releasing too much radiation. See JA4422

(“It is . . . apparent from review of the data 

that said operations at the Apollo Site are 

not conducted so as to provide a minimal 

radiological impact on the 

environment . . . .”). The same letter further 

states that there was heightened radioactivity 

in the area near the Apollo facility, many 

times in multiple of the background 

radiation because of “radiologically 

contaminated gaseous effluents.” Id.
15

 A July 9, 1974 internal memorandum

complains about “stack and liquid discards 

of SNM [special nuclear material] from the 

Apollo Plant” and tremendous losses of 

uranium through “gross irresponsibility.” 

See JA4427. 

However, AEC/NRC approved NUMEC’s 

operations at least three times. First, in a report 

timestamped July 29, 1966, the AEC wrote, “No item of 

noncompliance with respect to [NUMEC’s] 

concentrations of radioactive effluents released to 

unrestricted areas was noted as a result of this 

investigation.” JA5051. Second, in 1968, the AEC 

concluded that NUMEC’s roof edge samples were below 

the maximum permissible concentrations. JA5057 (“As 

can be seen, these average sample results are below 8.8 

[dpm/m3].”). On May 26, 1969, the AEC granted an 

amendment to NUMEC’s license, “authoriz[ing] the 

discharge of radioactive material from any stack 

effluent . . . in concentrations up to one-hundred . . . 

times the applicable limits . . . in accordance with the 

statements, representations and conditions specified in 

your application dated March 5, 1969.” JA5112. 

Finally, in 1995, the NRC issued a report 

investigating another NUMEC facility in Parks, 

Pennsylvania. See 60 Fed. Reg. 35,571, 35,573 (1995). 

In that report, the NRC stated that, despite the 1969 

license amendment setting limits for stack emissions, the 
16

regulatory limits were set at the boundary of the roof: 

“Accordingly, even though NUMEC was authorized to 

discharge at the stack up to 100 times the value specified 

in Appendix B, Table II, [under the 1969 license 

amendment,] NUMEC was still required to meet the 

limits at the site boundary (see footnote 8).” 60 Fed. 

Reg. 35,571, 35,573 (1995). Footnote 8, in turn, states, 

“The values set forth in 10 CFR Part 20, Appendix B, 

Table II, are the regulatory limits applicable at the site 

boundary, not at the stack.” 60 Fed. Reg. 35,571, 35,573 

n.8 (1995).

II. THE SCIENCE OF CANCER

This Court’s previous opinion, In re TMI 

Litigation, 193 F.3d 613 (3d Cir. 1999), set forth the 

basic scientific principles regarding the relationship 

between radiation and cancer. See 193 F.3d at 629–55. 

No party disputes those background principles. Because 

we rely on these principles here, we consider it helpful to 

summarize them. Ionizing radiation can damage human 

cells. Id. at 639–40. “If cellular damage is not repaired, 

[the damage] may prevent the cell from surviving or 

reproducing, or it may result in a viable but modified 

cell.” Id. at 640. When an irradiated cell is only 

“modified rather than killed,” stochastic (or probabilistic) 

effects result. Id. at 642. 

As the word “probabilistic” indicates, what 

happens next to the modified cell is uncertain. In some 

cases, “cancer induction” occurs. Id. As we explained in 
17

In re TMI Litigation, any increase in radiation exposure 

above zero is believed to increase the probability of 

carcinogenesis7: 

The probability that cancer will result from 

radiation increases proportionally with dose. 

However, it is currently believed that there 

is no threshold dose below which the 

probability of cancer induction is zero. . . . 

The linear risk model posits that each time 

energy is deposited in a cell or tissue, there 

is a probability of the induction of cancer.

Id. at 642–43 (citations omitted). 

Even with state-of-the-art data, it is impossible to 

determine with certainty that radiation is the cause of a 

given incidence of cancer for three reasons. First, 

numerous factors other than radiation may cause cancer. 

That is, “a given percentage of a defined population will 

contract cancer even absent any exposure to ionizing 

radiation.” Id. a 643–44.8 Second, there is no clear 

 

7

“Carcinogenesis is currently believed to be a multistep 

process requiring two or more intracellular events to 

transform a normal cell into a cancer cell.” In re TMI 

Litig., 193 F.3d 613, 643 (3d Cir. 1999). 

8

“[T]he task of establishing causation is greatly 

complicated by the reality that a given percentage of a 
18

difference between cancers caused by radiation or by 

other factors. No characteristic of a given cancer (such 

as its type or severity) are known to suggest that 

“manmade” radiation or even any radiation was the 

cancer’s cause. See id. at 643 (“[M]edical evaluation, by 

itself, can neither prove nor disprove that a specific 

malignancy was caused by a specific radiation 

exposure.”). Third, because the relevant changes occur 

on the cellular level, they are not detected or detectable at 

the time they occur. It can take many years—seemingly 

a variable number of years—between an exposure to 

radiation and the “possible detection of a resulting 

cancer.” Id. (defining the “latency period” as “[t]he 

period between exposure to radiation and possible 

detection”). Thus, in a case like this one, the factfinder 

will always have to use ex-post data to ascertain whether 

any radiation—let alone any particular radioactive 

exposure—disrupted the cell in the past. 

 

defined population will contract cancer even absent any 

exposure to ionizing radiation. In industrialized 

countries where the life expectancy averages about 70 

years, about 30% of the population will develop cancer 

and about 20% of the population will die of cancer.” In 

re TMI Litig., 193 F.3d at 643–44. 
19

III. THE DISTRICT COURT’S RELEVANT 

RULINGS

We are reviewing the orders granting Defendants’ 

motion for summary judgment. In its summary judgment 

orders, the District Court adopted the reasoning of the

Magistrate Judge to whom all pretrial motions had been 

referred. See Order, McMunn v. Babcock & Wilcox 

Power Generation Grp., No. 2:10-cv-00143-DSC-RCM 

(W.D. Pa. Aug. 24, 2011), ECF No. 79. 

Two earlier rulings set the stage for the summary 

judgment motion. Those two rulings are (1) a September 

12, 2012 order following a “Lone Pine” case 

management order,9and (2) a February 27, 2014 order 

adopting in part and rejecting in part the Magistrate 

Judge’s recommendations with regard to excluding the 

parties’ experts under Daubert v. Merrell Dow 

Pharmaceuticals, Inc., 509 U.S. 579 (1993).

 

9 A Lone Pine order is a pretrial order, based on Lore v. 

Lone Pine Corp., No. L-33606-85, 1986 WL 637507

(N.J. Super. Ct. Law Div. Nov. 18, 1986), that “require[s]

plaintiffs to provide facts in support of their claims” 

including by expert evidence “or risk having their cases 

dismissed.” In re Asbestos Prods. Liab. Litig. (No. VI), 

718 F.3d 236, 240 & n.2 (3d Cir. 2013).
20

A. Lone Pine

On January 25, 2012, the Magistrate Judge issued 

the Lone Pine order, requiring Plaintiffs to provide prima 

facie evidence of, among other things, the “name of the 

specific radionuclide(s) released from Defendants’ 

facilities in excess of the applicable federal permissible 

limits” and “an identification of each exposure 

pathway(s) through which each Plaintiff was exposed to 

each specific radionuclide.” Order at 1, McMunn v. 

Babcock & Wilcox Power Generation Grp., No. 2:10-cv0143-DSC-RCM (W.D. Pa. Jan. 25, 2012), ECF No. 109.

On September 12, 2012, following the parties’ 

responses to the Lone Pine order, the Magistrate Judge 

issued an order limiting Plaintiffs’ theories of recovery. 

See McMunn v. Babcock & Wilcox Power Generation 

Grp., 896 F. Supp. 2d 347 (W.D. Pa. 2012). In that 

order, the Magistrate Judge held that the Plaintiffs would 

be allowed only “to pursue, offer or rely upon evidence 

referring or relating to any claim based upon exposure 

through . . . airborne exposure to uranium . . . from . . . 

the Apollo facility during its years of operation.” Id. at 

358–61; see also id. at 364. Plaintiffs do not challenge 

this Lone Pine order on appeal. 

B. Daubert

On July 12, 2013, the Magistrate Judge 

recommended that the District Court (1) grant some of 

Defendants’ Daubert motions; (2) deny the remainder of 
21

Defendants’ Daubert motions; and (3) deny all of 

Plaintiffs’ Daubert motions. See McMunn v. Babcock & 

Wilcox Power Generation Grp., Nos. 10-143 et al., 2013 

WL 3487560 (W.D. Pa. July 12, 2013). Specifically, the 

Magistrate Judge recommended excluding the testimony 

of Plaintiffs’ three general causation experts—Dr. 

Howard Hu, Dr. Joseph Ring, and Mr. Bernd Franke—

and Plaintiffs’ specific causation expert, Dr. James 

Melius. Only the rulings with regard to Melius’s 

testimony bear directly on this appeal.

Melius’s expert report used the methodology of 

differential diagnosis. Melius provided a roughly onepage summary of each Plaintiff’s background and alleged 

exposure and then concluded for each Plaintiff: “[I]t is 

my professional medical opinion that [Plaintiff’s] 

exposures to uranium and other radioactive materials 

released from the Apollo nuclear facility made a 

significant contribution to the development of” his or her 

cancer. E.g., JA3448, 3465, 3490. For most of the 

Plaintiffs, Melius added language substantially like the 

following: “This is reinforced by the lack of other risk 

factors in [her or his] history that would account for the 

development of this illness.” E.g., JA3448.10 

 

10 For a handful of Plaintiffs—but only some of the 

Plaintiffs with a history of smoking—Melius identified 

smoking as the only confounding factor. E.g., JA3451 
22

The Magistrate Judge recommended excluding 

Melius’s testimony because Melius failed to rule out 

other confounding factors and did not have information 

about doses of radiation to which each Plaintiff was 

exposed. With regard to confounding factors, the 

Magistrate Judge criticized Melius’s “differential 

diagnosis” because Melius “fail[ed] to explain why he 

did not rule out smoking, obesity, genetic factors, 

benzene exposure, radon and many other possible and 

obvious alternative causes in order to conclude in each 

instance that uranium is the cause of the individual’s 

cancer.” McMunn, 2013 WL 3487560, at *28. With 

regard to dose, the Magistrate Judge criticized Melius for 

failing to make or use any estimate of any Plaintiff’s dose 

“or the maximum or minimum amount to which the 

person was exposed.” Id. at *29. Instead, to determine 

that Plaintiffs’ exposures were sufficient to serve as a 

“significant contribution” to their cancers, Melius relied 

on general testimony about radiation—Dr. Hu’s 

testimony that radiation from uranium could cause 

cancer—and the assumption that Plaintiffs were exposed 

to dangerous levels of radiation because “the Plaintiffs 

lived or worked within 1.5 miles of the Apollo facility.” 

 

(“This is reinforced by the lack of other risk factors in his 

history that would account for the development of this 

illness other than smoking which also would have made a 

contribution.”).
23

Id. at *28. The Magistrate Judge’s two criticisms 

dovetailed with a particular flaw in Melius’s testimony: 

Melius “rule[d] out oral contraceptive use if the dose was 

small and smoking if the person quit 10–15 years ago, 

thereby taking dose into account.” Id. at *29. The 

Magistrate Judge concluded that Melius’s methodology 

“has not been generally accepted in the medical and 

scientific communities” and was “untestable.” Id. at *29.

On February 27, 2014, the District Court rejected 

the Magistrate Judge’s report and recommendation to the 

extent that the Magistrate Judge recommended granting 

Defendants’ Daubert motions with regard to Melius and 

Plaintiffs’ general causation experts.11 With regard to 

Melius specifically, the District Court placed great 

weight on (1) this Court’s past discussion of differential 

diagnosis methodology and (2) the fact that Melius did 

not have access to perfect information. First, the District 

Court held that Melius “adequately addressed other 

possible causes of Plaintiffs’ cancers, both known and 

 

11 The District Court adopted the portion of the report and 

recommendation in which the Magistrate Judge 

recommended denying the exclusion of Defendants’ 

experts and denying the exclusion of most of Plaintiffs’ 

experts. See McMunn v. Babcock & Wilcox Power 

Generation Grp., Nos. 2:10cv143 et al., 2014 WL 

814878, at *20 (W.D. Pa. Feb. 27, 2014). 
24

unknown” because Melius reviewed information about 

the Plaintiffs. McMunn v. Babcock & Wilcox Power 

Generation Grp., Nos. 2:10cv143 et al., 2014 WL 

814878, at *14 (W.D. Pa. Feb. 27, 2014). The District 

Court also cited and quoted In re Paoli Railroad Yard 

PCB Litigation, 35 F.3d 717 (3d Cir. 1994), and Heller v. 

Shaw Industries, Inc., 167 F.3d 146 (3d Cir. 1999), for 

the propositions that a medical expert performing a 

differential diagnosis does not need to rule out every 

alternative factor and that medical experts are permitted

to exercise their judgments when conducting a 

differential diagnosis. See McMunn, 2014 WL 814878,

at *15.

Second, with regard to dose, the District Court 

held that there was “enough support in the record for the 

contention that the Plaintiffs’ exposure levels exceeded 

the normal background level” for Melius to use a 

“qualitative analysis” rather than a “quantitative dose 

analysis.” Id. at *14. In particular, Melius could rely on 

“NUMEC’s failure to monitor emissions.” Id. Because 

Melius’s analysis relied on the absence of data, the 

District Court agreed with Melius that a “quantitative 

dose calculation . . . may in fact be far more speculative 

than a qualitative analysis.” Id. 

The District Court further held that a dose analysis 

was not necessary for Plaintiffs’ claims to succeed. The 

District Court stated that In re TMI Litigation, 193 F.3d 

613 (3d Cir. 1999), “did not require a plaintiff prove a 
25

quantified dose in order to prove personal injuries caused 

by the release of radiation.” McMunn, 2014 WL 814878, 

at *13. Then, the District Court cited to other cases that 

did not require a dose. Id. at *13–14 (quoting and citing 

Kannankeril v. Terminix Int’l, 128 F.3d 802, 808–09 (3d 

Cir. 1997), Bonner v. ISP Techs., Inc., 259 F.3d 924 (8th 

Cir. 2001), and Westberry v. Gislaved Gummi AB, 178 

F.3d 257 (4th Cir. 1999)). 

At Defendants’ request, the District Court certified 

the Daubert order for interlocutory appeal. See McMunn 

v. Babcock & Wilcox Power Generation Grp., Nos. 

2:10cv143 et al., 2014 WL 12530940 (W.D. Pa. May 7, 

2014). We denied Defendants’ petition for interlocutory 

appeal. See McMunn v. Babcock & Wilcox Power 

Generation Grp., No. 14-8074 (3d Cir. June 16, 2014).

C. Summary Judgment

On May 7, 2015, the Magistrate Judge filed a very 

thorough report recommending that the District Court 

grant Defendants’ motion for summary judgment on 

Plaintiffs’ Price-Anderson public liability claims and 

Defendants’ motion for a judgment on the pleadings on 

all of Plaintiffs’ common-law claims. See McMunn v. 

Babcock & Wilcox Power Generation Grp., 131 F. Supp. 
26

3d 352, 359–404 (W.D. Pa. Sept. 15, 2015) (republishing 

the report and recommendation).12

The Magistrate Judge recommended that the 

District Court grant summary judgment because 

Plaintiffs (1) failed “to raise a genuine issue for trial on 

breach of duty” and (2) failed “to proffer evidence of 

exposure and dose.” Id. at 389, 404.13 First, with regard 

to the breach of duty, the Magistrate Judge held that 

“[t]he regulatory standard applicable to the emission of 

radionuclides in airborne effluent to off-site areas . . . 

when the Apollo facility operated . . . was 10 C.F.R. 

§ 20.106”—“not some other regulation, license 

requirement or other issue.” Id. at 368–69, 388; see also 

In re TMI, 67 F.3d 1103, 1108 n.10 (3d Cir. 1995) 

 

12 Because Plaintiffs did not appeal the District Court’s 

adoption of the Magistrate Judge’s recommendation to 

dismiss Plaintiffs’ common-law claims, we need not 

discuss the common-law claims. 

13 The Magistrate Judge did not reach any other issues 

regarding Plaintiffs’ Price-Anderson public liability 

claims. As the Magistrate Judge noted, Defendants 

raised other issues in separate summary judgment 

motions that the District Court denied as moot or denied 

without prejudice to refile. See McMunn, 131 F. Supp. 

3d at 361 & n.3, 404.
27

(applying “the relevant federal regulations . . . in place at 

the time” of the radioactive release caused by Three Mile 

Island accident at issue). 

Section 20.106 prohibited a licensee from 

“releas[ing] to an unrestricted area radioactive material in 

concentrations which exceed the limits specified in 

Appendix ‘B’, Table II of this part.” 10 C.F.R. 

§ 20.106(a) (1980). The regulation further states that 

“the concentration limits in Appendix ‘B’, Table II of 

this part shall apply at the boundary of the restricted 

area.” 10 C.F.R. § 20.106(d).

The Magistrate Judge rejected Plaintiffs’ argument 

that the Table II maximum permissible concentration 

applied directly to the uranium effluent released from the 

stacks on the roof. First, the Magistrate Judge 

determined that the roof of the Apollo facility was a 

restricted area. McMunn, 131 F. Supp. 3d at 386–87. 

Second, the Magistrate Judge held that the measurements 

of uranium effluent to be compared to the maximum 

permissible concentration should be those taken “at the 

roof boundary.” Id. at 387–88. Because Plaintiffs’ only 

expert testimony about breach applied the concentration 

limits at the stacks and not at the roof boundaries, the 

Magistrate Judge held that Plaintiffs failed to proffer 

expert evidence of a breach that raised a genuine issue of 

material fact. See id. at 389.

With regard to exposure and dose, the Magistrate 

Judge held that Plaintiffs’ causation case failed because 
28

Plaintiffs failed to show that each Plaintiff was exposed 

to enough radiation to cause his or her cancer. First, the 

Magistrate Judge granted Defendants’ motion to deem 

certain facts admitted. See id. at 394; Plaintiffs’ Local 

Rule 56.C.1 Response, No. 2:10-cv-001343-DSC-RCM 

(W.D. Pa. filed Dec. 5, 2014), ECF No. 342. Then, the 

Magistrate Judge explained that, under In re TMI 

Litigation, 193 F.3d 613 (3d Cir. 1999), each Plaintiff 

had to show that he or she was exposed to “inhaled 

uranium from the Apollo plant in excess of normal 

background radiation amounts.” McMunn, 131 F. Supp. 

3d at 396–97, 399. Thus, the Magistrate Judge held that 

“Plaintiffs must provide . . . an estimate of the dose they 

received which caused their cancers.” Id. at 399. As 

discussed above, Melius relied on Plaintiffs’ other 

experts for exposure, but none of Plaintiffs’ other experts 

calculated exposure or dose for any of the Plaintiffs. See 

id.

Further, the Magistrate Judge rejected Plaintiffs’ 

argument that Defendants were “estopped from 

contesting [Plaintiffs’] lack of evidence of exposure and 

dose” because Defendants failed to keep accurate 

records. Id. at 402–04. The Magistrate Judge also 

rejected Plaintiffs’ argument that law of the case required 

the Magistrate Judge to deny summary judgment on 

causation because the District Court had ruled that 

Melius’s testimony was admissible in its Daubert ruling. 

See id. at 399–402. 
29

On September 15, 2015, the District Court adopted 

the Magistrate Judge’s report and recommendation over 

Plaintiffs’ objections. See id. at 357. The District Court

stated that it “review[ed] . . . the record of these 

cases, . . . the Magistrate Judge’s Report and 

Recommendation, and the Objections thereto,” but 

offered no further explanation for its decision. Id.

Certain related cases were not consolidated with 

the main case when the District Court issued its 

September 15, 2015 Memorandum Order. The District 

Court ultimately entered orders adopting the reasoning of 

the September 15, 2015 Memorandum Order in those 

cases. See JA281–92; SJa3–SJa8.

Timely notices of appeal followed in each case 

before us.14 Additionally, Defendants cross-appealed 

many—but not all—of the cases before us, requesting 

that we reverse the District Court’s Daubert order.

 

14 Plaintiffs’ Notices of Appeal also objected to orders 

excluding the expert report of Dr. Steve Wing. See, e.g., 

Ja1. Because Plaintiffs presented no argument regarding 

Dr. Wing’s report, any issues or objections concerning it 

have been waived. 
30

JURISDICTION

The District Court had subject-matter jurisdiction 

over these actions under 42 U.S.C. § 2210(n)(2) because 

this is a public liability action arising out of a nuclear 

incident in the Western District of Pennsylvania. This 

Court has jurisdiction over Plaintiffs’ appeals under 28 

U.S.C. § 1291.

Plaintiffs argue that we did not have jurisdiction 

over Defendants’ cross-appeal relating to the District 

Court’s denial of their Daubert motion regarding Melius 

because Defendants are not aggrieved by that denial. As 

the Supreme Court observed in Deposit Guaranty 

National Bank v. Roper, “Ordinarily, only a party 

aggrieved by a judgment or order of a district court may 

exercise the statutory right to appeal therefrom. A party 

who receives all that he has sought generally is not 

aggrieved by the judgment affording the relief and cannot 

appeal from it.” 445 U.S. 326, 333 (1980); see also

Nanavati v. Burdette Tomlin Mem’l Hosp., 857 F.2d 96, 

102 (3d Cir. 1988) (“Because they are completely 

satisfied with the final judgment and object only to 

interlocutory rulings of the district court, we lack 

jurisdiction over their appeal.”).

We need not determine whether we have 

jurisdiction. We simply follow Third Circuit practice and 

dismiss Defendants’ cross-appeals as “superfluous.” 

Smith v. Johnson & Johnson, 593 F.3d 280, 283 n.2 (3d 

Cir. 2010) (“Yet a party, without taking a cross-appeal, 
31

may urge in support of an order from which an appeal 

has been taken any matter appearing in the record, at 

least if the party relied on it in the district court.”). As 

such, we consider the parties’ Daubert arguments to 

concern causation only as an “alternate ground for 

affirmance.” Nanavati, 857 F.2d at 102. Accordingly, 

we have disregarded Defendants’ reply brief in support 

of their cross-appeal.

STANDARD OF REVIEW

The standard of review on summary judgment is 

well known: “Because we are reviewing a grant of 

summary judgment, our standard of review is plenary. 

Summary judgment is appropriate ‘if the movant shows 

that there is no genuine dispute as to any material fact 

and the movant is entitled to judgment as a matter of 

law.’” Constitution Party of Pa. v. Cortes, 824 F.3d 386, 

393 (3d Cir. 2016) (citations omitted) (quoting Fed. R. 

Civ. P. 56(a)). 

DISCUSSION

We will affirm the judgment of the District Court 

because Plaintiffs failed to raise an issue of fact that 

would allow a reasonable jury to find that Defendants 

breached their duty and because Melius’s conclusory 

expert report would not allow a reasonable jury to find 

that Defendants’ radiation was a substantial factor in 

causing Plaintiffs’ cancers. 
32

I. DUTY

The District Court15 held that Plaintiff failed to 

establish a genuine issue of material fact as to whether 

Defendants breached their duty to Plaintiffs. We agree 

with the District Court that Defendants’ duty was defined 

by § 20.106.

In three different ways, Plaintiffs try to show that 

Defendants owed a duty other than to prevent the release 

of uranium effluent that exceeds the maximum 

permissible concentrations at the boundary of the roof, 

when the effluent is averaged over a full year. First, 

Plaintiffs argue that any emission from the roof counts 

under § 20.106. Second, Plaintiffs argue that more 

onerous maximum permissible concentrations for roof 

emissions were created by the 1969 amendment to 

NUMEC’s license. And, third, Plaintiffs argue that they 

had the option to decline annual averaging, allowing 

them to find breaches of duty where emissions exceeded 

 

15 Because the District Court “adopt[ed] the Report and 

Recommendation as the Opinion of [the District] Court,” 

McMunn v. Babcock & Wilcox Power Generation Grp., 

131 F. Supp. 3d 352, 357 (W.D. Pa. 2015), “we will refer 

to the adopted opinion as that of the district court,” USX 

Corp. v. Liberty Mut. Ins. Co., 444 F.3d 192, 197 n.8 (3d 

Cir. 2006).
33

the maximum permissible concentration over short 

periods of time. As discussed below, these attempts to 

redefine the duty fail because they all conflict with 

§ 20.106 and because we owe Auer deference to the 

NRC’s interpretation of § 20.106. 

A. The Roof Was a Restricted Area

Under § 20.106(d), the maximum permissible 

concentrations are assessed “at the boundary of the 

restricted area.” 10 C.F.R. § 20.106(d). A “restricted 

area” is any area where “access . . . is controlled by the 

licensee for purposes of protection of individuals from 

exposure to radiation and radioactive materials.” 10 

C.F.R. § 20.3(a)(14). Plaintiffs argue that the entire roof 

was unrestricted16 such that emissions from anywhere on 

the roof—including the stacks and fans—should count 

directly against the limits. Plaintiffs’ argument is 

undermined by a 1995 NRC report that states that the 

“regulatory limits [are] applicable at the site boundary, 

 

16 The definition of “unrestricted area” is merely a mirror 

of the definition of “restricted area”: “‘Unrestricted area’ 

means any area access to which is not controlled by the 

licensee for purposes of protection of individuals from 

exposure to radiation and radioactive materials, and any 

area used for residential quarters.” 10 C.F.R. 

§ 20.3(a)(17).
34

not at the stack.” 60 Fed. Reg. 35,571, 35,573 n.8 

(1995). 

Plaintiffs present two arguments as to why the roof 

is unrestricted: (1) an historical argument based on a 

series of letters between the AEC and NUMEC and (2) a 

functional argument that questions whether access to the 

roof was “controlled by the licensee for purposes of 

protection of individuals from exposure to radiation and 

radioactive materials.”

With regard to the historical argument, Plaintiffs’ 

strongest support is a June 5, 1964 letter, in which the 

Director of the Division of State and Licensee Relations 

of the AEC stated that the roof would be “unrestricted” if 

access were not controlled: “[T]he roof area of the 

NUMEC facility is an unrestricted area unless access to 

this area is controlled from the radiation safety 

standpoint.” JA5314. 

Plaintiffs also rely on other correspondence in 

which NUMEC and AEC compared stack emissions to 

the applicable maximum permissible concentration. For 

instance, in a 1967 report, a NUMEC employee wrote, 

“[T]he measured stack concentration frequently exceeds 

permissible levels.” JA5201. The AEC similarly 

expressed concern about releases from stacks, as though 

the regulations created limitations on the stacks. In a 

February 5, 1969 letter, the Director of the Division of 

Compliance of the AEC warned, “Based on your 

recorded data, the concentrations of radioactive material 
35

released from the facility through exhaust stacks to 

unrestricted areas exceed the limits specified in Appendix 

B, Table II of 10 CFR 20, contrary to 10 CFR 20.105(a), 

‘Concentrations in effluents to unrestricted areas.’” 

JA4700. Additionally, the fact that NUMEC sought—

and the AEC granted in 1969—approval to exceed the 

maximum permissible concentration by one-hundred 

times at the stack, see JA5112, suggests that there was a 

pre-existing regulatory limit at the stack. 

Plaintiffs’ functional argument focuses on the 

definition of a restricted area in the regulation. The 

regulation states that a “restricted area” is any area where 

“access . . . is controlled by the licensee for purposes of 

protection of individuals from exposure to radiation and 

radioactive materials.” 10 C.F.R. § 20.3(a)(14). It is 

uncontested that the roof could only be accessed by

locked hatches from ladders located inside the building. 

See JA5035–36 (“There are no outside ladders on 

NUMEC’s property. We have two inside ladders with 

normally closed and locked hatches at the top.”); JA5317 

(“The roof hatch is kept locked with keys in the 

possession of the health and safety technician.”).17 

 

17 Plaintiffs argue that NUMEC conceded that the roof is 

unrestricted based on the 1966 letter from NUMEC to the 

AEC that states, “We regard the roof area as an 

unrestricted area.” JA4649. The District Court 
36

Plaintiffs argue that these hatches do not show that 

the roof was “controlled . . . for purposes of 

protection . . . from exposure to radiation.” Relying on a 

1965 NUMEC letter, they argue that certain safety 

measures—e.g., alpha survey instruments—are required 

to show why the access is controlled. See Pls.’ Br. 40–

41. 

 

concluded that “unrestricted” was “a typographical 

error.” McMunn v. Babcock & Wilcox Generation Grp., 

131 F. Supp. 3d 352, 378 (W.D. Pa. 2015). At summary 

judgment, district courts should not determine whether a 

particular phrasing is a scrivener’s error when other 

possibilities are reasonable. See, e.g., Coffill v. Coffill, 

656 F.3d 93, 95–96 (1st Cir. 2011) (holding that it was 

error to rule that a purported scrivener’s error existed 

“without evidentiary hearing and evidentiary basis”). We 

agree with the District Court that, in the context of the 

correspondence in the record and the surrounding 

sentences, it would be unreasonable or absurd to read that 

sentence in the 1966 letter as a concession that NUMEC 

considered the roof “unrestricted.” The same paragraph 

explains the unrestricted areas were at the “roof edge”: 

“[T]he roof edge air samplers are measuring directly the 

concentration being discharged to unrestricted areas.” 

JA5317. 
37

Ultimately, we defer to the expertise of the NRC as 

to where the restricted area of the Apollo facility ended. 

In 1995, the NRC issued a report investigating another 

NUMEC facility in Parks, Pennsylvania. 60 Fed. Reg. 

35,571, 35,573 (1995). Even though the report was about 

the Parks facility, the NRC referred to the 1969 letter that 

allowed NUMEC to exceed regulatory limits at the 

Apollo facility’s stacks. The NRC stated that, despite a 

1969 license amendment setting limits for stack 

emissions, the regulatory limits were set at the boundary 

of the roof. “Accordingly, even though NUMEC was 

authorized to discharge at the stack up to 100 times the 

value specified in Appendix B, Table II, [under a 1969 

license amendment,] NUMEC was still required to meet 

the limits at the site boundary (see footnote 8).” Id. 

Footnote 8, in turn, stated, “The values set forth in 10 

CFR Part 20, Appendix B, Table II, are the regulatory 

limits applicable at the site boundary, not at the stack.” 

Id. at 35,573 n.8.

Under Auer v. Robbins, 519 U.S. 452, 461–62 

(1997), we defer to the NRC’s “fair and considered 

judgment” of its interpretation of its regulation. One 

could argue that the NRC should receive less deference 

to the extent that the NRC’s 1995 position conflicts with 

Plaintiffs’ historical evidence. In this case, we believe 

we still owe full deference. The Supreme Court’s main 

concern with an agency switching positions has been 

with circumstances in which the new position could 

cause “unfair surprise.” Long Island Care at Home, Ltd. 
38

v. Coke, 551 U.S. 158, 170–71 (2007) (“[A]s long as 

interpretive changes create no unfair surprise[,] . . . the 

change in interpretation alone presents no separate 

ground for disregarding the Department’s present 

interpretation.”). Here, our Auer deference would not 

harm any reliance interests.

Even if we did not defer to the NRC, Defendants’ 

interpretation of a “restricted area” is more consistent 

with our precedent than is Plaintiffs’ functional 

argument. In 1995, we held that “[t]he definitions of 

‘restricted’ and ‘unrestricted areas’ demonstrate that the 

C.F.R. sections governing persons in ‘unrestricted areas’

were intended to cover persons outside a nuclear plant’s 

boundaries, i.e., the general public.” In re TMI, 67 F.3d 

at 1114 (footnote omitted). Although denial of access to 

the “general public” alone does not turn a space into a 

restricted area, our understanding has been focused more 

on whether a licensee exercises control rather than on the 

precise safety measures chosen by the licensee. Other 

than the isolated statements by NUMEC, Plaintiffs give 

us no reason to believe that more than locked hatches

were needed to control access to the roof for purposes of 

protecting individuals from radiation. 

B. The License Did Not Create a Duty

As noted above, in 1969, the AEC approved 

NUMEC’s request to amend its license to allow “the 

discharge of radioactive material from any stack . . . in 

concentrations up to one-hundred (100) times the 
39

applicable limits specified in Appendix B, Table II,” 

contingent on satisfactory sampling “at the plant roof 

perimeter” and “in the neighboring unrestricted areas of 

[the] plant.” JA5112. Plaintiffs argue that this 1969 

license amendment now creates a tort duty that 

Defendants violated by discharging more than 100 times 

the maximum permissible concentration at the stacks. 

In a Price-Anderson public liability claim, “federal

law preempts state tort law on the standard of care.” In 

re TMI, 67 F.3d at 1107. Our 1995 opinion in In re TMI

instructs that the duty that survives preemption must be a 

regulatory requirement meant to protect people like 

Plaintiffs. Following In re TMI, we look to the principles 

of negligence per se (by analogy) and to other courts’ 

interpretation of duty under the Price-Anderson Act. 

Because this license requirement was only meant to make 

it easier to assess whether NUMEC violated 10 C.F.R. 

§ 20.106 at the boundary of the restricted area—not to 

create an independent obligation—we hold this license 

requirement does not supply a tort duty.

In the 1995 TMI case, plaintiffs argued that the “as 

low as is reasonably achievable” principle (“ALARA”) 

established the tort duty. This Court held instead that 10 

C.F.R. §§ 20.105, 106 established the relevant duty. Two 

of our major considerations were that (1) §§ 20.105 and 

20.106 indicated they should apply to effluent emissions 

to the public, In re TMI, 67 F.3d at 1114, and (2) the 

ALARA regulation states that it was not “to be construed 
40

as radiation protection standards” but was rather meant to 

be a discretionary tool for regulatory agencies, id. at 

1114–15 (internal quotation mark omitted). Thus, we see 

that our concerns in 1995 reflected (1) whether the 

regulation was meant to cover the persons allegedly 

affected and (2) whether the regulation was meant to 

establish actual standards or operating principles for the 

agency. These same considerations are not present here. 

The limitations on the stacks were meant to show levels 

below which there could not be a violation at the 

boundary. Thus, they were not directly protective of 

persons in unrestricted areas and were a discretionary 

choice by the AEC to make policing NUMEC easier. 

The 1995 TMI case also instructs us to consider 

principles from negligence per se. In that case, we 

explained that the duty analysis under the Price-Anderson 

Act “is analogous to the practice followed by many 

jurisdictions with negligence per se cases. In such cases, 

where defendants violated the relevant statute or 

regulation, courts have held as a matter of law that 

plaintiffs have satisfied the first two elements of their 

cause of action: the duty and breach of duty.” In re TMI,

67 F.3d at 1118. 

Plaintiffs’ objection that we would nullify the 

license requirements if we refused to use them as the 
41

standard of care18 assumes that every legal requirement 

must be enforceable by a civil plaintiff. That assumption 

is contrary to fundamental principles of negligence per 

se, under which courts must ask “whether the policy 

behind the legislative enactment will be appropriately 

served by using it to impose and measure civil damage 

liability.” Frederick L. v. Thomas, 578 F.2d 513, 517 n.8 

(3d Cir. 1978).

Negligence per se only attaches to a statutory or 

administrative duty when its direct effect is to prevent the 

harm at issue to the type of person allegedly injured. See

Byrne v. Matczak, 254 F.2d 525, 528 (3d Cir. 1958) 

(“[T]he general principle is that the violation of a statute 

will not create a liability unless it is the efficient cause of 

the injury.”); Congini ex rel. Congini v. Portersville 

Valve Co., 470 A.2d 515, 518 (Pa. 1983); Restatement 

(Second) Torts § 286.19 We have held that “general 

 

18

“To hold that NUMEC had no duty to obey the AEC’s 

regulatory caps stated in its license would be tantamount 

to holding that the AEC had no authority to set those 

limits.” Pls.’ Br. 35.

19 When we adopted 10 C.F.R. §§ 20.105 and 20.106 as 

the standard of care, we cited Restatement (Second) of 

Torts for the proposition that a court can adopt 

regulations as the standard of care. See In re TMI, 67 

F.3d at 1113 n.24.
42

licensing or permit schemes do not usually establish 

standards of competence; they do not usually represent 

judgments that a violation of the licensing scheme will 

generally constitute the breach of a duty to a particular 

person rather than to the state.” Beaver Valley Power 

Co. v. Nat’l Eng’g & Contracting Co., 883 F.2d 1210, 

1221–22 (3d Cir. 1989); see also Talley v. Danek Med., 

Inc., 179 F.3d 154, 159 (4th Cir. 1999) (“Even if the 

regulatory scheme as a whole is designed to protect the 

public or to promote safety, the licensing duty itself is not 

a standard of care, but an administrative requirement.”); 

Restatement (Second) of Torts § 288 (“The court will not 

adopt as the standard of conduct . . . the requirements 

of . . . administrative regulation whose purpose is found 

to be exclusively . . . to protect the interests of the state or 

any subdivision of it as such.”).20 

 

20 Following oral argument, Plaintiffs filed a letter under 

Rule 28(j) of the Federal Rules of Appellate Procedure 

with additional cases that showed regulations creating 

tort duties. None of them is contrary to the reasoning 

above. Rather, Plaintiffs’ 28(j) cases pertain to situations 

in which statutes explicitly create a duty for license 

violations, see 33 U.S.C. § 1365(a) (“[A]ny citizen may 

commence a civil action on his own behalf . . . against 

any person . . . who is alleged to be in violation of . . . . 

an effluent standard.”); 33 U.S.C. § 1365(f) (“[T]he term 

‘effluent standard or limitation under this chapter’
43

Finally, as in 1995, we look to other circuits’ 

caselaw as “instructive.” In re TMI, 67 F.3d at 1113. 

Here, we see that no other circuit has adopted Plaintiffs’ 

proposed standard. See Adkins v. Chevron Corp., 960 F. 

Supp. 2d 761, 766, 772–73 (E.D. Tenn. 2012) (holding 

that license violations do not create duty in a PriceAnderson public liability action).

The history of the license amendment shows that 

its purpose was not to create an independent duty to 

minimize discharge from the stacks. On November 13, 

1968, Roger D. Caldwell, NUMEC Manager, Health and 

Safety, sent a letter to Donald A. Nussbaumer at the 

AEC. The letter requested a change to NUMEC’s license 

that would “permit[] concentrations up to 100 MPCa in 

any stack’s effluent, providing the concentration at the 

roof edge is permissible.” JA5073. Caldwell justified 

 

means . . . a permit or condition thereof . . . .”); N.Y. 

Veh. & Traffic Law § 509(3) (“Whenever a permit or 

license is required to operate a motor vehicle, no person 

shall operate any motor vehicle in violation of any 

restriction contained on, or applicable to, the permit or 

license.”), or situations where preemption of alternative 

laws is not as complete as here, see Gomez v. St. Jude 

Medical Daig Div. Inc., 442 F.3d 919, 928–30 (5th Cir. 

2006) (discussing the scope of preemption relating to the 

Medical Device Amendments).
44

the request by pointing to empirical data relating to 

diffusion factors at the Apollo facility—that is, by 

showing that amounts released at the stacks would be 

much less at the roof edge. See JA5074–76.

On February 5, 1969, Lawrence D. Low, AEC, 

Director, Division of Compliance wrote to Zalman 

Shapiro, NUMEC President. Low wrote that “the 

concentrations of radioactive material released from the 

facility through exhaust stacks to unrestricted areas 

exceed the limits . . . contrary to 10 CFR 20.106(a).” 

JA5079–80. In the same section of the letter, Low 

acknowledged NUMEC’s request that its license “be 

amended to permit use of a dilution factor for stack 

effluents.” JA6080. 

On February 25, 1969, Shapiro responded, 

explaining that a higher concentration limit could be 

applied at the stacks to determine whether NUMEC 

violated its maximum permissible concentration at the 

roof edge: 

We recognize the necessity for an 

amendment to our license which would 

reflect appropriately the means of varifying 

[sic] the effectiveness of atmospheric 

dilution in reducing concentration in 

unrestricted areas. In this connection, we 

submitted on November 13, 1968 a request 

for an amendment to our license which 

would place primary reliance on roof 
45

perimeter sampling in lieu of stack sampling 

as a means of measuring releases to 

unrestricted areas. At a meeting on January 

17, 1969 with Licensing and Compliance 

personnel, it was concluded that the off-site 

environment sampling program should be 

included as a part of our license amendment 

application to provide additional assurance

with respect to the effectiveness of 

atmospheric dilution. Accordingly, we are 

preparing and will submit by March 7, 1969 

a revised application which, if approved, 

should provide an acceptable means of 

varifying [sic] compliance with Part 20.

JA5083–84. 

On March 10, 1969, Caldwell submitted a “revised 

application to permit concentration to 100 MPCa in any 

stack’s effluent.” JA5087. Again, Caldwell “justified” 

the proposed limits by pointing to empirical data showing 

dilution factors at the roof perimeter. Id.

On May 26, 1969, Nussbaumer at the AEC wrote 

to Caldwell at NUMEC granting the amendment to 

NUMEC’s license “to authorize the discharge of 

radioactive material from any stack effluent . . . in 

concentrations up to one-hundred . . . times the 

applicable limits . . . in accordance with the statements, 

representations and conditions specified in your 

application dated March 5, 1969.” JA5112 (emphasis 
46

added). Nussbaumer added, “We consider the 

environmental sampling program required by Condition 

2 above to be a means for providing backup data and 

evidence that your roof edge sampling results are 

adequately representative of the concentrations released 

to the unrestricted areas.” JA5112–13 (emphasis added). 

Thus, even at the time, the AEC, via Nussbaumer, 

accepted NUMEC’s “representations” about the 

relationship between the stack discharges and the roof 

edge and that the roof edge monitors would be used to 

determine the concentrations “released to the unrestricted 

areas.”

In 1995, the NRC agreed that NUMEC’s purpose 

in seeking the amendment assumed that all requirements 

would be met if the emission at the boundaries were 

below the maximum permissible concentration: “By 

application dated November 13, 1968, and supplement 

dated March 5, 1969, and pursuant to 10 CFR 20.106(b), 

NUMEC requested that License SNM-145 be amended to 

permit concentrations up to 100 times the limits specified 

in Part 20, Appendix B, Table II, in any stack effluent, 

provided that concentrations at the roof edge and in the 

local environment complied with 10 CFR Part 20 limits.” 

In re Babcock & Wilcox Co., 41 N.R.C. 489, 492–93 

(June 26, 1995); see also 10 C.F.R. § 20.106(b). Thus, it 

is clear that the stack-discharge license restriction was 

created as a threshold to test for emissions at the 

boundary of the restricted area. 
47

Because the license requirement was only an 

administrative safe harbor for NUMEC’s compliance 

with the emissions maximum set at the boundary of the 

restricted area, it does not create a tort duty here. 

C. Plaintiffs Had to Show that Maximum Permissible 

Concentration was Exceeded on Average Over a Full 

Year

Section 20.106 states, “For purposes of this 

section[,] concentrations may be averaged over a period 

not greater than one year.” 10 C.F.R. § 20.106(a) (1980). 

The District Court’s holding that Plaintiffs failed to show 

a genuine issue of material fact regarding duty was based 

on Plaintiffs’ failure to show a violation of § 20.106 

when averaged over the course of a year: “Plaintiffs 

have pointed to no genuine issues of material fact that the 

annual average concentration of uranium effluent ever 

exceeded 1.7 x 10-2 microcuries/milliliter during the 

period 1957–1960, or that it ever exceeded 4.0 x 10-12

microcuries/milliliter during the period 1961–1983.” 

McMunn, 131 F. Supp. 3d at 388. On appeal, Plaintiffs 

continue to argue that they could show a violation based 

on a discharge that exceeds the maximum permissible

concentration over any length of time. Plaintiffs are 

plainly wrong.

Plaintiffs’ argument is based entirely on the word 

“may” in the phrase “concentrations may be averaged 

over a period not greater than one year.” They argue, 

“The term may is permissive, not mandatory. There is no 
48

requirement to take an average.” Pls.’ Br. 43 (footnote 

omitted). We agree with Plaintiffs that “may” is 

permissive. See, e.g., Simpson v. Kay Jewelers, Div. of 

Sterling, Inc., 142 F.3d 639, 650–51 (3d Cir. 1998) 

(comparing “the more flexible and permissive ‘may’” to 

“the mandatory ‘must’” (quoting Torre v. Casio, Inc., 42 

F.3d 825, 831 n.6 (3d Cir. 1994))).

But Plaintiffs’ reliance on a single word in that 

phrase ignores the fact that it is part of a sentence that 

speaks in the passive voice. “Phrases constructed in the 

passive voice use an implied subject or actor who carries 

out the verb.” Sci. Drilling Int’l, Inc. v. Pathfinder 

Energy Servs., Inc., No. H-06-1634, 2006 WL 2882863, 

at *3 (S.D. Tex. Oct. 4, 2006). Thus, the question is who

has the discretion to decide whether to average annually. 

Given the context of the regulation, the obvious 

answer is that such discretion lies in the AEC because it 

is the entity charged with determining whether a licensee 

violates its regulatory duties. Cf. United States v. 

Brumbaugh, 909 F.2d 289, 291 (7th Cir. 1990) (“The use 

of the passive voice in the statutory language requires us 

to infer a subject; the most logical inference is that the 

Attorney General, who has been charged with granting 

credit under section 3568 for over thirty years, is the 

intended subject of the sentence.”). Plaintiffs’ unwritten 

assumption that the AEC intended for tort plaintiffs or 

district courts to have discretion to use annual averaging 

is mistaken. Giving tort plaintiffs the power to determine 
49

retroactively the period over which a violation is assessed 

“would allow [them] to fix the standard case by case and 

plant by plant. An operator acting in the utmost good 

faith and diligence could still find itself liable for failing 

to meet such an elusive and undeterminable standard.” 

In re TMI, 67 F.3d at 1115. Under § 20.106, Plaintiffs 

were required to show a breach using annual averaging. 

Their data relating to individual moments in time fails to 

show a breach.

* * *

Plaintiffs’ attempts to expand Defendants’ duty 

must fail. The maximum permissible concentration is 

assessed at the boundary of the roof, the license 

requirement does not create a duty, and Plaintiffs must 

show that the maximal permissible concentration was 

exceeded when the emissions are averaged annually.

II. BREACH

The District Court held that Plaintiffs failed to 

show there was a dispute of fact as to whether 

Defendants emitted excessive radiation at the boundary 

of the roof because Plaintiffs failed to offer appropriate 

expert testimony.21 On appeal, Plaintiffs again rely 

 

21 See McMunn, 131 F. Supp. 3d at 389 (“In addition, to 

establish a breach of duty, Plaintiffs must offer evidence 
50

almost entirely on data from the stacks and roof fans, 

which, as was established above, are legally irrelevant. 

See, e.g., Pls.’ Reply Br. 15–16 (“NUMEC officials were 

all too aware of the problem with the roof fans.”). 

Putting aside the stacks and fans data, we agree that 

Plaintiffs’ argument for breach fails for lack of expert 

evidence in this highly technical area. 

Moreover, Plaintiffs argue that they are “entitled” 

to “adverse inferences” that allow them to show a breach 

(and also causation). See Pls.’ Br. 22. This, too, fails

because Plaintiffs did not show that the District Court 

abused its discretion in denying the adverse inference.

A. Plaintiffs Needed Experts

Plaintiffs failed to provide an expert who could 

testify that the data upon which they rely (stacks, vents, 

and readings from outside the facility) could show a 

violation of the maximum permissible concentration of 

uranium effluent at the boundary of the roof when 

averaged annually. 

Expert evidence is generally required when an 

issue is beyond the ken of a lay jury. For instance, in a 

medical monitoring claim, we explained that the plaintiff 

 

from a qualified expert that the Apollo facility’s 

emissions exceeded regulatory limits.”).
51

had to prove he or she suffered a “significantly increased 

risk of contracting a serious latent disease” and other 

factors “by competent expert testimony.” Redland 

Soccer Club, Inc. v. Dep’t of Army of U.S., 55 F.3d 827, 

845–46, 852 (3d Cir. 1995).

22

 Similarly, then-Judge 

Sotomayor wrote for the Second Circuit that expert 

testimony would be “necessary” where “an injury has 

multiple potential etiologies.” Wills v. Amerada Hess 

Corp., 379 F.3d 32, 46 (2d Cir. 2004). 

 

22 Cf. also Boring v. Kozakiewicz, 833 F.2d 468, 473 (3d 

Cir. 1987) (“In some situations in which the seriousness 

of injury or illness would be apparent to a lay person, 

expert testimony would not be required, e.g., a gunshot 

wound. However, those circumstances are not present 

here.” (citation omitted)); Breidor v. Sears, Roebuck & 

Co., 722 F.2d 1134, 1140–41 (3d Cir. 1983) (stating that 

expert testimony was necessary to rebut the defendants’ 

contention in a products liability case); Lentino v. Fringe 

Emp. Plans, Inc., 611 F.2d 474, 480 (3d Cir. 1979) 

(“Expert testimony is required to establish the relevant 

standard and whether the defendant complied with that 

standard, except where the matter under investigation is 

so simple, and the lack of skill so obvious, as to be within 

the range of the ordinary experience and comprehension 

of non-professional persons.” (citations omitted) 

(Pennsylvania medical malpractice case)).
52

Perhaps recognizing their failure to transmute vent 

data into roof data, Plaintiffs try to borrow an “average 

dilution factor of 50” from an isolated 1968 document. 

See Pls.’ Br. 45. But these kinds of calculations are best 

suited to experts—not lawyers or lay factfinders.

B. The District Court Did Not Abuse Its Discretion in 

Holding That Plaintiffs Were Not Entitled to an 

Inference Sufficient to Survive Summary Judgment

Objecting to the report and recommendation, 

Plaintiffs argued that Defendants’ poor recordkeeping 

allowed them to request an inference under which a jury 

could assume that Defendants had breached the abovedescribed duty. [See Dist. Ct. ECF No. 376, at 50–53.] 

By adopting the Magistrate Judge’s report and 

recommendation, the District Court rejected this 

argument. See McMunn, 131 F. Sup. 3d 352.

We review the District Court’s denial of the 

adverse inference for abuse of discretion. See, e.g., In re 

Hechinger Inv. Co. of Del., Inc., 489 F.3d 568, 574 (3d 

Cir. 2007) (“We also review the [bankruptcy court’s] 

denial of UFP's motion seeking an evidentiary inference 

based on spoliation of evidence for abuse of discretion.”);

Davis v. White, 858 F.3d 1155, 1160 (8th Cir. 2017) 

(“The district court’s refusal to sanction the officers with 

an adverse inference instruction was not an abuse of 

discretion.”).
53

Plaintiffs have failed to show that the District 

Court abused its discretion when determining that an 

adverse inference was not warranted here.23 Plaintiffs 

simply have not developed their argument sufficient to 

show an abuse of discretion. [See Pls.’ Br. 21–22.] In 

cases where this argument is more developed, an adverse 

inference may be appropriate. See United States ex rel. 

Scutellaro v. Capitol Supply, Inc., No. 10-1094 (BAH), 

2017 WL 1422364, at *11 (D.D.C. Apr. 19, 2017) 

(noting several circuits have held that the failure to 

maintain records allows for an adverse inference). This 

can be seen by analogy to spoliation cases. In spoliation

cases, where there is evidence that one party has 

destroyed or altered evidence, the opposing party can 

obtain a “‘spoliation inference,’ that the destroyed 

evidence would have been unfavorable to the position of 

the offending party.” Schmid v. Milwaukee Elec. Tool 

Corp., 13 F.3d 76, 78 (3d Cir. 1994). Here, because 

 

23 Plaintiffs’ recordkeeping argument also relates to their 

failure to provide expert evidence relating to any 

individual Plaintiff’s exposure. See, e.g., Pls.’ Reply Br. 

18 (“NUMEC’s failure to collect data makes calculations 

impossible—and it should not now benefit from its own 

malfeasances.”). Plaintiffs have also failed to show the 

District Court abused its discretion when it denied an 

adverse inference with regard to causation. See 

McMunn, 131 F. Supp. 3d at 394–96. 
54

Plaintiffs failed to show an abuse of discretion, we need 

not analyze further.

III. CAUSATION

The District Court held that Plaintiffs’ case also 

must be dismissed because Plaintiffs’ experts failed to 

provide “evidence of [Plaintiffs’] exposure to inhaled 

uranium from the Apollo plant and an estimate of the 

dose they received which caused their cancers.” 

McMunn, 131 F. Supp. 3d at 399. On appeal, Plaintiffs 

argue they showed causation even though they did not 

show a dose for any individual plaintiff because (1) 

Plaintiffs needed only to show “frequency, regularity, 

and proximity”—not dose—and (2) the law of the case 

requires us to assume that Melius’s testimony would be 

sufficient to show causation because the District Court 

ruled Melius’s testimony was admissible in its Daubert 

motion. These arguments are unpersuasive because 

Plaintiffs’ experts failed to show that any of the 

individual Plaintiffs had sufficient exposure—looking at 

the frequency, regularity, and proximity to the 

radiation—and Plaintiffs were not prejudiced by the 

District Court’s inconsistent reasoning. 

A. Plaintiffs Do Not Show Sufficient Frequency, 

Regularity, and Proximity

Unlike with duty and breach discussed above, 

causation for Price-Anderson public liability actions is 

evaluated under state law. See In re TMI, 67 F.3d 1103, 
55

1117 n.33 (3d Cir. 1995) (“As we have noted, the 1988 

Amendments retroactively required the applicable law 

for ‘public liability actions’ be ‘the law of the State in 

which the nuclear incident involved occurs, unless such 

law is inconsistent’ with federal law.”); see also In re 

Hanford Nuclear Reservation Litig., 534 F.3d 986, 1010 

(9th Cir. 2007) (“Under the PAA, Washington state law 

controls the standard of causation to be used in this 

case.”). Here, that state law is Pennsylvania law.

Pennsylvania requires a plaintiff to show that a 

defendant’s acts were a substantial factor in causing a 

plaintiff’s injury. As the Pennsylvania Supreme Court 

recently stated, “To establish proximate causation, a 

plaintiff must adduce evidence to show that the 

defendant’s act was a substantial factor in bringing about 

the plaintiff’s harm.” Rost v. Ford Motor Co., 151 A.3d 

1032, 1049 (Pa. 2016); see also Summers v. Certainteed 

Corp., 997 A.2d 1152, 1164–65 (Pa. 2010) (“[T]he 

requirements of proving substantial-factor causation 

remain the same.”).

Until recently, the Pennsylvania Supreme Court 

had suggested that proving substantial-factor causation 

required showing the dose to which plaintiff was exposed 

because otherwise the “substantiality” of the substantial 

factor would not be shown to the jury. See Betz v. 

Pneumo Abex LLC, 44 A.3d 27, 58 (Pa. 2012) 

(“Certainly a complete discounting of the substantiality 
56

in exposure would be fundamentally inconsistent with 

Pennsylvania law.”). 

However, following oral argument in the case

before us, the Pennsylvania Supreme Court issued its 

decision in an asbestos case, Rost v. Ford Motor Co. In 

Rost, the Pennsylvania Supreme Court retreated from its 

earlier statements, emphasizing that it had previously 

“adopted the ‘frequency, regularity, and proximity’ test, 

as refined and applied by the United States Court of 

Appeals for the Seventh Circuit in Tragarz v. Keene 

Corp., 980 F.2d 411 (7th Cir. 1992).” Rost, 151 A.3d at 

1043. 

It may well be that Rost applies only in 

mesothelioma cases because of unique public policy 

concerns about mesothelioma.24 Yet we need not decide 

 

24 See, e.g., Rost, 151 A.3d at 1042–43 (describing the 

“test on motions for summary judgment in mesothelioma 

cases”); id. at 1044 n.7 (“It is important to recognize that 

this Court settled on these principles based on a policy 

concern: that it is fundamentally unfair to hold a 

defendant jointly and severally liable for a mesothelioma 

plaintiff’s injuries for a de minimis contribution to the 

plaintiff’s overall exposure.”); id. at 1052 (stating that the 

frequency, regularity, and proximity test applied “for all 

exposures to asbestos”). This makes particular sense to 

the extent that Rost relies on Tragarz, which, in turn is 
57

 

based on an Illinois appellate court’s reliance on the 

nature of asbestos-related diseases: 

Given the various diseases which are 

associated with asbestos exposure, the 

medical evidence presented, the types of 

asbestos involved, the manner in which the 

products are handled, and the tendency of 

those asbestos products to release asbestos 

fibers into the air, the amount of evidence 

needed to establish the regularity and 

frequency of exposure will differ from case 

to case. For example, none of the plaintiffs 

in this case were diagnosed with 

mesothelioma, an asbestos-related disease 

which is caused after only minor exposure to 

asbestos dust. 

Wehmeier v. UNR Indus., Inc., 572 N.E.2d 320, 337 (Ill. 

App. Ct. 1991) (citation omitted). 

Mesothelioma is a “signature” disease relating to 

asbestos exposure; individuals do not usually develop 

mesothelioma without asbestos exposure. See Daley v. 

A.W. Chesterton, 37 A.3d 1175, 1177 n.4 (Pa. 2012) 

(“Moreover, because mesothelioma, in general, is so rare, 

‘any case occurring after a well attested and substantial 

asbestos exposure is commonly accepted as being caused 
58

 

by that exposure.’”); see also Ford Motor Co. v. Boomer, 

736 S.E.2d 724, 728 (Va. 2013) (“Mesothelioma is a 

signature disease: it was uncontroverted at trial that the 

cause of mesothelioma is exposure to asbestos at some 

point during an individual's lifetime.”). 

By contrast, the cancers suffered by the Plaintiffs have 

numerous and sometimes even unknowable causes, as 

Melius conceded. See JA3236 (“We're evaluating a 

disease that’s multi-causal. We don’t have any way of 

testing the cancer to determine what caused it, what 

specific factor caused it.”); JA3237 (“There are many 

cancers that occur where we don’t identify the cause of 

that cancer or the causes of that cancer.”); JA3311 (“In 

an individual patient I think it’s more appropriate to use 

risk factors because it implies -- otherwise it implies that 

we know the factor that caused their specific individual 

cancer and in most cases we probably do not.”); see also

Risk Factors for Cancer, Nat’l Cancer Institute, 

https://www.cancer.gov/about-cancer/causesprevention/risk (last visited Oct. 15, 2016) (identifying 

age, alcohol, cancer-causing substances, chronic 

inflammation, diet, hormones, immunosuppression, 

infectious agents, obesity, radiation, sunlight, and 

tobacco as risk factors for cancer).

Indeed, in 1999, we explained that establishing causation 

for a given cancer was extremely difficult. See In re TMI 
59

whether Rost is limited to mesothelioma cases because 

Plaintiffs’ evidence would not allow a jury to find 

sufficient frequency, proximity, and regularity. Rost

requires a plaintiff at summary judgment to have 

propounded “evidence that exposure to defendant’s 

asbestos-containing product was sufficiently ‘frequent, 

regular, and proximate’ to support a jury’s finding that 

defendant’s product was substantially causative of the 

disease.” Rost, 151 A.3d at 1044 (emphasis added). For 

 

Litig., 193 F.3d at 643 (“Consequently, medical 

evaluation, by itself, can neither prove nor disprove that a 

specific malignancy was caused by a specific radiation 

exposure.”). Modern secondary sources continue to 

agree with that assessment. See, e.g., Steve C. Gold, 

When Certainty Dissolves into Probability: A Legal 

Vision of Toxic Causation for the Post-Genomic Era, 70 

Wash. & Lee L. Rev. 237, 279–81 (2013); William D. 

O’Connell, Note, Causation’s Nuclear Future: Applying 

Proportional Liability to the Price-Anderson Act, 64 

Duke L.J. 333, 357, 359 (2014) (“Radiation-protection 

scientists are in agreement that differential diagnosis 

cannot confidently identify the ultimate source of a 

plaintiff’s cancer.”); cf. Wilcox v. Homestake Mining Co., 

619 F.3d 1165, 1167 (10th Cir. 2010) (“[N]or do we see 

a basis for alternative liability where only one potential 

wrongdoer has been identified and the injury may simply 

have resulted from natural causes.”).
60

instance, the Rost Court noted that the plaintiff’s expert 

testified to more than three months of exposure “while 

noting studies showing that a single month of regular 

exposure to asbestos can double one’s likelihood of 

developing mesothelioma.” Id. at 1046. Even 

Lohrmann—the original frequency, regularity, and 

proximity case, which stated that the court was creating 

“a de minimis rule” for proving asbestosis causation

under Maryland law—explained that “a plaintiff must 

prove more than a casual or minimum contact with the 

product.” Lohrmann v. Pittsburgh Corning Corp., 782 

F.2d 1156, 1162 (4th Cir. 1986). Here, where Plaintiffs 

(1) simply rely on the existence of any frequency, 

regularity, and proximity and (2) fail to offer any 

individualized evidence of exposure for any given 

Plaintiff, they come up short. Even were this evidence 

substantively permissible under Pennsylvania law, it 

would fail to be admissible under Daubert for three 

reasons.

First, Melius’s testimony is insufficient to create a 

genuine issue of fact regarding causation because it is 

nothing more than a radiation version of the 

impermissible “any breath” theory in Gregg v. V-J Auto 

Parts (the case in which that court first adopted the 

frequency, regularity, and proximity test in mesothelioma 

cases). See Summers, 997 A.2d at 1161 n.14 (“In Gregg 

v. V-J Auto Parts, Co., 596 Pa. 274, 943 A.2d 216 

(2007), this Court recently rejected the viability of the 

‘each and every exposure’ or ‘any breath’ theory.”). The 
61

Gregg Court explained that, in a so-called “any breath” 

theory of asbestos exposure, a plaintiff alleges that “any 

exposure to asbestos, no matter how minimal, is a 

substantial contributing factor in asbestos disease.” 

Gregg v. V-J Auto Parts, Co., 943 A.2d 216, 226 (Pa. 

2007); see also Howard v. A.W. Chesterton Co., 78 A.3d 

605, 608 (Pa. 2013) (per curiam) (“Bare proof of some de 

minimus [sic] exposure to a defendant’s product is 

insufficient to establish substantial-factor causation for 

dose-responsive diseases.”). 

Melius assumes that anyone who lived in the area 

of the Apollo facility was exposed to a sufficient amount 

of radiation. In Melius’s words, he “estimated that -- that 

they had a, um, substantial or significant exposure.”

JA3227. Yet he did not “estimate a specific or associate 

a specific level of exposure with a -- with those terms.” 

Id. When asked about “significant exposure,” Melius 

agreed that “any exposure to a plaintiff that was above 

that plaintiff’s background would be a substantial 

exposure.” JA3315.

25 Similarly, Melius said that, 

 

25 This is in contradiction to, for instance, his admissions 

that he relied on different levels of cigarette usage to 

determine substantiality. See JA3300, 3308; see also 

JA3321 (“For cigarette smoking and lung cancer, it is 

reduced to ten or twenty percent increased risk compared 

to somebody who has never smoked after a period of say 

twenty years, maybe even after ten or fifteen years.”).
62

“[d]epending on how you use the meaning of 

significant,” he “would say” one millirem above 

background was “substantial.” JA3315–16. 

Second, Melius failed to offer individualized 

testimony as he was required to do for each Plaintiff. For 

instance, in Howard v. A.W. Chesterton Co., the 

Pennsylvania Supreme Court explained, “Relative to the 

testimony of an expert witness addressing substantialfactor causation in a dose-responsive disease case, some 

reasoned, individualized assessment of a plaintiff’s or 

decedent’s exposure history is necessary.” 78 A.3d at 

608; cf. also Black v. M&W Gear Co., 269 F.3d 1220, 

1237–38 (10th Cir. 2001) (holding that a district court 

did not abuse its discretion in excluding an expert’s 

testimony when that expert “had not based his conclusion 

on the results of tests or calculations specific to” the 

plaintiff). Although Melius describes each Plaintiff’s 

smoking history and a few other features for most 

Plaintiffs, Melius fails to offer any “reasoned . . . 

assessment” of any individual’s exposure to radiation 

from uranium effluent. See, e.g., JA4782–84 (relying on 

reports about radiation released from the facility that do 

not show exposure to any of the individual Plaintiffs). 

He merely offers the conclusion that each Plaintiff’s 

“exposures to uranium and other radioactive materials 

released from the Apollo nuclear facility made a 

significant contribution to the development of” her or his 

cancer. E.g., JA3448. Even if such a conclusion were 

permissibly individualized, it would still be insufficient 
63

to generate a genuine issue of fact because, under the 

Lone Pine order, only exposure to uranium is at issue 

here. 

Although Rost stresses that causation is an issue 

for the jury, we have never hesitated to grant summary 

judgment where one side fails to establish a genuine issue 

of fact concerning causation. See, e.g., In re TMI Litig., 

193 F.3d 613, 722–23 (3d Cir. 1999) (affirming summary 

judgment where plaintiff’s expert testimony “was 

insufficient to create a genuine issue of material fact” 

regarding causation); Heller v. Shaw Indus., Inc., 167 

F.3d 146, 150 (3d Cir. 1999) (“[B]ecause the District 

Court did not abuse its discretion in excluding the key 

elements of Heller’s experts’ testimony necessary to 

prove causation, the grant of summary judgment will be 

affirmed.”).

Finally, the Federal Rules of Evidence impose a 

duty on a district judge to act as a gatekeeper of expert 

testimony even when considering elements of a cause of 

action derived from state law. See Forrest v. Beloit 

Corp., 424 F.3d 344, 358 n.9 (3d Cir. 2005) (explaining 

that “evidentiary issues in this case are governed by 

federal . . . law” while Pennsylvania substantive law 

affected what facts would be relevant); see also Hendrix 

ex rel. G.P. v. Evenflo Co., Inc., 609 F.3d 1183, 1193 

(11th Cir. 2010) (“Although the standards for finding 

causation are governed by Florida law, we apply federal 

law to determine whether the expert testimony proffered 
64

to prove causation is sufficiently reliable to submit it to 

the jury.”); cf. Daubert v. Merrell Dow Pharm., Inc., 509 

U.S. 579, 597 (1993) (“[A] gatekeeping role for the 

judge . . . is the balance that is struck by Rules of 

Evidence . . . .”).

Thus, even assuming arguendo that Rost

resuscitated “any breath” causation, Melius’s testimony 

would be too insubstantial to survive Daubert. Melius’s 

testimony provides only a perfunctory narrative for each 

Plaintiff, and an unexplained conclusion that radiation 

was the cause, presumably because each Plaintiff was 

exposed to some radiation. Such conclusory opinions of 

medical causation, even by qualified experts, are 

insufficient to establish causation of cancer by exposure 

to uranium effluent. See Tamraz v. Lincoln Elec. Co., 

620 F.3d 665, 671 (6th Cir. 2010) (“Whatever Dr. Carlini 

understood by ‘with a reasonable degree of medical 

certainty,’ the phrase—the conclusion by itself—does not 

make a causation opinion admissible. The ‘ipse dixit of 

the expert’ alone is not sufficient to permit the admission 

of an opinion.” (quoting Gen. Elec. Co. v. Joiner, 522 

U.S. 136, 146 (1997))).

Although we have held that an expert can offer an 

opinion “absent hard evidence of the level of exposure to 

the chemical in question,” we have only done so where 

an expert could rely “on the temporal relationship and the 

nature of the plaintiff’s complaints.” Heller, 167 F.3d at 

157. This, too, does not require a dose. But it requires 
65

more than an assumption about the effect of living within 

a mile of the Apollo facility.

* * *

Consider how a trial would unfold. Plaintiffs 

would present a general causation expert who opines that 

any amount of ionizing radiation could cause cancer. 

Then, Plaintiffs would present Melius who would state 

that each of the Plaintiffs lived or worked near the Apollo 

facility and would therefore be assumed to have been 

exposed to some radiation from airborne uranium 

effluent from the Apollo facility. Melius would then 

presumably testify that he is certain that the additional 

radiation specifically from the airborne uranium was a 

substantial factor in causing the cancer of each of the 

Plaintiffs.26 Finally, the jury would decide whether more 

than a dozen different illnesses suffered by more than 

seventy people were each caused by the radiation from 

the airborne uranium from the Apollo facility.

How? Without any ability to compare any 

plaintiff’s frequency, proximity, or regularity to any 

evidence showing that a given frequency, proximity, or 

regularity is correlated with any particular increase in 

 

26 Plaintiffs would also have to ensure they have 

sufficient testimony relating only to uranium effluent 

under the Lone Pine order.
66

risk—let alone the ability to perform the ideal 

comparison between dose and the dose-responsiveness of 

a given illness—the jury would be engaging in rank 

speculation.

It is true that demanding more than evidence of 

“any exposure” makes it more burdensome for most 

plaintiffs to recover for injuries from radiation. But the 

evidentiary regime that must apply in these cases 

necessarily requires that a jury find radiation was a 

substantial factor in causing a plaintiff’s injury—and 

requires, now, at summary judgment, that we be able to 

hold that a reasonable jury could so find. See Gregg, 943 

A.2d at 225–26 (“We appreciate the difficulties facing 

plaintiffs in this and similar settings, where they have 

unquestionably suffered harm on account of a disease 

having a long latency period and must bear a burden of 

proving specific causation under prevailing Pennsylvania 

law which may be insurmountable.”); see also Fed. R. 

Civ. P. 56(a). We can demand no less.

B. District Court Law of the Case Does Not Bind This 

Court, and, in Any Event, Plaintiffs Were Not 

Prejudiced

Pointing to the inconsistency between the District 

Court’s Daubert opinion, which suggested Melius’s 

testimony was strong, and the District Court’s opinion 

granting summary judgment to Defendants, which held 

that Melius’s testimony did not create a genuine issue of 

material fact, Plaintiffs argue that the District Court was 
67

bound to adhere to its Daubert opinion at summary 

judgment. Such concerns are irrelevant where, as here,

(a) this Court is not bound by the District Court’s 

Daubert opinion and (b) Plaintiff cannot show prejudice.

Plaintiffs are correct that the District Court’s 

Daubert opinion appears to be inconsistent with its 

summary judgment opinion. The Daubert opinion 

strongly implied that Melius’s testimony would be 

enough to get the case to the jury, holding that his 

testimony should not be excluded because there was 

“enough support in the record for the contention that the 

Plaintiffs’ exposure levels exceeded the normal 

background level.” McMunn v. Babcock & Wilcox 

Power Generation Grp., Nos. 2:10cv143 et al., 2014 WL 

814878, at *14 (W.D. Pa. Feb. 27, 2014). By contrast, 

the District Court’s summary judgment opinion held that 

“Plaintiffs must provide . . . an estimate of the dose they 

received which caused their cancers.” McMunn, 131 F. 

Supp. 3d at 399.

But, as a general matter, we fail to see what 

difference law of the case makes at this stage of the 

litigation. We are not bound by either of the District 

Court’s rulings, and we have addressed the Plaintiffs’

arguments on their own merits. 

At all events, Plaintiffs’ law-of-the-case argument 

fails on its own merits. Two values animate law-of-thecase doctrine: judicial economy and unfair prejudice. 

See, e.g., Roberts v. Ferman, 826 F.3d 117, 126 (3d Cir. 
68

2016) (“We also have held that ‘the law of the case 

doctrine does not limit the power of trial judges to 

reconsider their prior decisions,’ but have noted that 

when a court does so, it must explain on the record why it 

is doing so and ‘take appropriate steps so that the parties 

are not prejudiced by reliance on the prior ruling.’”

(quoting Williams v. Runyon, 130 F.3d 568, 573 (3d Cir. 

1997))). 

Here, Plaintiffs have failed to show any prejudice 

from the District Court’s change in position. Had the 

District Court ruled against them in its Daubert order, 

Plaintiffs’ case would have been dismissed as the 

Magistrate Judge recommended. Plaintiffs would not 

have had an opportunity to create new expert reports in 

response to a Daubert ruling that more clearly reflected 

the District Court’s legal rulings on causation at 

summary judgment. 

Perhaps Plaintiffs could have argued that they 

were prejudiced because they were lulled into failing to 

challenge Defendants’ uncontested facts. But, because 

we do not rely on any of those uncontested facts when we 

hold that Plaintiffs fail to show a genuine dispute of 

material fact with regard to causation, not even the 

admission of the uncontested facts demonstrates 

prejudice.

* * *
69

Because Plaintiffs failed to offer evidence from 

which a jury could find that each plaintiff was exposed to 

radiation from Defendants’ uranium effluent sufficiently 

frequently, regularly, and proximately to substantially 

cause their illnesses, and further because the law-of-thecase doctrine does not require us to conclude otherwise, 

we hold that Defendants have failed to demonstrate 

issues of material fact on causation.

CONCLUSION

Defendants are entitled to judgment as a matter of 

law because Plaintiffs failed to show a genuine issue of 

material fact with regard to duty, breach, and causation. 

Therefore, we will affirm the judgment of the District 

Court. 
1

McMunn, et al. v. Babcock & Wilcox Power Generation 

Group, Inc., et al., No. 15-3506

MCKEE, Circuit Judge, concurring, joined by RESTREPO, 

Circuit Judge.

While I agree that summary judgment is appropriate here, 

I write to stress that the law in this area is simply inadequate 

to address claims arising under the Price-Anderson Act based 

on exposure to excess radiation.

As the Majority explains, this is a Public Liability Action 

under the Price-Anderson Act.1 Federal law therefore 

controls our inquiry into whether Defendants owed Plaintiffs

a duty, and if so, whether the duty was breached. State law 

controls the inquiry into whether the breach, if proven, caused 

Plaintiffs’ injuries.2 As I will explain, existing law places an 

almost insurmountable burden on plaintiffs who try to recover 

under the Price-Anderson Act. Under the existing law, 

Plaintiffs cannot establish causation, even if they have 

established that Defendants owed them a duty that was 

breached. 

Suits for injuries allegedly resulting from radiation 

exposure have no analogous counterpart in traditional tort 

law, and existing law ignores the unique problems inherent in 

claims based on exposure to “manmade” radiation. As a 

result, plaintiffs will rarely, if ever, recover in these types of 

actions, and this will continue unless states (or Congress) 

recognize the unique problems endemic in proving that a 

plaintiff’s illness was proximately caused by exposure to 

radiation from a given facility or event.

I. BREACH OF DUTY

I believe that Plaintiffs’ submissions (as itemized in 

the Majority Opinion) are more than adequate to survive 

Defendants’ motion for summary judgment as to breach of 

duty.

3

 For example, an internal memorandum, dated 

 

1 Maj. Op. at 5. 

2 See In re TMI, 67 F.3d 1103, 1117 n.33 (3d Cir. 1995). 

3 See Maj. Op. at 10-12. 
2

2

November 29, 1972, regarding NUMEC’s meeting with AEC 

Compliance stated: 

P. Nelson [AEC personnel] opened by 

explaining the purpose of the meeting. He 

stated that Compliance was concerned about the 

recurring nature and seriousness of NUMEC 

violations. He explained that the AEC could 

now impose civil penalties for those types of 

violations. . . . NUMEC has been the worst 

offender of AEC regulations over the years. . 

. . AEC had given NUMEC a grace period after 

the B&W takeover, but that little improvement 

was evident. The AEC is strongly considering 

imposing civil penalties against NUMEC.4

Another letter from the AEC stated: “It appears that certain of 

your activities were not conducted in full compliance with . . .

and the requirements of the AEC’s ‘Standards for Protection 

Against Radiation,’ Part 20, and ‘Special Nuclear Material’ . . 

. .”

5 Based on this, there could be enough evidence to support 

Plaintiffs’ claimed breach of duty.

The Majority affirms the District Court’s conclusion

that much of Plaintiffs’ evidence is of either limited value or 

irrelevant because the only expert whose testimony survived 

the Daubert motion (Dr. Melius) primarily focused on 

radiation levels at the stacks or vents and not at the roof top 

boundary.6 Although I agree that Plaintiffs must establish the 

levels of radiation at the roof boundary rather than levels at 

the vents or stacks, levels at the vents or stacks could

nevertheless be very relevant to establishing levels at the 

boundary if that evidence had been properly developed. This 

follows from the fact that different radioactive substances 

have different half-lives. I will not wade into the quantum 

mechanical weeds of half-lives here as that was discussed in 

some detail in our 1999 opinion in In re TMI Litigation (TMI 

II).

7

 Rather, I will merely note that half-lives vary from as 

short as less than a second to as long as many billions of 

 

4

JA4439-40 (emphasis added). 

5

JA4693.

6 See Maj. Op. at 23, 29-34. 

7 193 F.3d 613 (3d Cir. 1999). 
3

years, depending on the substance involved.8 Accordingly, if 

byproducts of the uranium produced at Defendants’ facility 

included substances with sufficiently long half-lives, their

levels at the stacks and vents would be very relevant to 

determining exposure at the roof boundary and beyond. A 

fact finder could readily conclude that the levels at the vents 

and stacks persisted with no discernable diminution (even 

after allowing for dilution as they dispersed into the 

surrounding community) long enough for residents of the 

community to be exposed to those levels. The probative 

value of this evidence could be particularly compelling if the 

effluents that comprise the byproducts of uranium production 

are not otherwise found in the environment. They would thus 

become much more analogous to toxins that cause diseases 

such as mesothelioma which I discuss in more detail below.

However, we do not know the extent to which 

byproducts of uranium production have an exceedingly short

half-life or whether they have exceptionally low energies. If 

they have a momentary short half-life or exceptionally low 

energies, their presence at the stacks and vents would be 

irrelevant to determining levels at the roof boundary. This is

because they would have disintegrated into sub particles 

before reaching the roof boundary and would likely not have 

had enough energy to cause any damage even if they reached 

the roof’s perimeter and beyond into the community. 

Plaintiffs did not offer any evidence that would allow a fact 

finder to conclude that the levels at vents and stacks persisted 

at the roof boundary. Accordingly, evidence of the levels at 

the stacks and vents cannot satisfy their burden of 

establishing a breach at the relevant point—the roof 

boundary. 

I also have reservations about the Majority’s 

conclusion that 10 C.F.R. § 20.106(a) requires averaging as 

opposed to merely allowing Plaintiffs to average exposure 

over a year.

9

 However, here again, Plaintiffs’ proof is 

deficient because they did not attempt to introduce any 

evidence about the actual content of the uranium effluent that 

was discharged. If that effluent contained substances that 

 

8 See id. at 632.

9 See Maj. Op. at 41-43.
4

4

were particularly toxic (such as plutonium), exposure to a 

given amount for a few days (perhaps even for a matter of 

hours) could cause cancer even though the exposure would 

appear minimal when averaged out over a year.10 There is an 

even more fundamental problem with Plaintiffs’ case that 

prevents them from surviving summary judgment, and that is 

why I feel compelled to write separately.

In order for Plaintiffs to succeed, they must do more 

than show a breach of a duty resulting in exposure to excess 

radiation. They must show that the breach resulted in an 

exposure that proximately caused their injuries. It is here that

Plaintiffs’ claims fail regardless of the quality of all of their 

other proof. Thus, even assuming a genuine issue of fact as 

to the exposure levels and Defendants’ breach, the evidence is 

still not sufficient to defeat summary judgment under the 

Price-Anderson Act because causation is lacking. 

II. CAUSATION

A. The Problems of Radiation Toxicity

The Majority thoroughly and correctly explains

causation as it applies to “toxic torts” under Pennsylvania

law. However, the legal principle of causation has evolved 

from suits arising from exposure to manmade toxic 

substances such as asbestos. As the Majority notes, 

mesothelioma is caused by exposure to asbestos, and it is 

therefore a “signature” disease. The disease almost never 

occurs absent exposure to asbestos.11 The problems of proof 

in such cases are quite similar to problems of causation in 

cases involving polychlorinated biphenyls (PCBs)12 or 

 

10 See George L. Voelz, Plutonium and Health: How Great is 

the Risk?, Los Alamos Sci. 83 (2000), 

https://fas.org/sgp/othergov/doe/lanl/pubs/00818013.pdf; 

Katherine Harmon, Health Risk Fears Escalate as Japan 

Nuclear Plant’s Radioactive Release Remains Uncertain, Sci. 

Am. (Mar. 18, 2011), 

https://www.scientificamerican.com/article/health-riskfukushima/ (“Plutonium is of graver concern because of its 

exceptionally long half-life (about 24,000 years) and its 

propensity to cause lung cancer if inhaled.”).

11 Maj. Op. at 50-51.

12 See In re Paoli R.R. Yard PCB Litig., 35 F.3d 717 (3d Cir. 

1994).
5

pneumoconiosis (black lung disease),13 to name but a few of 

the pathological byproducts of modernization. In such cases, 

a pathology is caused by contact (usually ingestion) with a 

foreign substance that the injured person would not have 

otherwise been exposed to, or would have been exposed to 

only in relatively insignificant quantities, and that pathology 

almost never occurs in the absence of exposure to that toxic 

substance. Accordingly, causation can be established by 

showing that defendant made (or controlled) a substance, 

plaintiff has a disease that almost never occurs absent contact 

with defendant’s substance, and plaintiff had sufficient 

contact with defendant’s product (i.e. “frequency, regularity, 

and proximity of exposure”) to allow a fact finder to conclude 

that the defendant’s product was a substantial factor in the 

plaintiff’s death or injury.14 Radiation is different.

In TMI II, we discussed the “scientific principles 

regarding the relationship between radiation and cancer.” 15 

As the Majority explains, “[m]anmade ionizing radiation can 

damage human cells.”16 An ion is nothing more than an 

electron that has been displaced from its orbit.17 Unlike with 

 

13 See Mancia v. Dir., Office of Workers’ Comp. Programs, 

U.S. Dep’t of Labor, 130 F.3d 579 (3d Cir. 1997).

14 See Rost v. Ford Motor Co., 151 A.3d 1032 (Pa. 2016).

15 Maj. Op. at 13-15; see TMI II, 193 F.3d 613.

16 Maj. Op. at 13 (citing TMI II, 193 F.3d at 639-40). 

Although we used the term “manmade” in TMI II, it is 

actually a misnomer that obscures some of the very important 

distinctions between environmental radiation naturally 

occurring and radiation from substances that are, in fact, 

manmade. The latter radiation is not actually “manmade.” It 

consists of natural elementary particles that are transformed 

by human activity. The resulting radiation is nevertheless the 

result of quantum mechanical processes. However, for the 

sake of convenience, we will also refer to this radiation as 

“manmade” as we did in TMI II.

17 TMI II, 193 F.3d at 639 (“[A]n atom is ionized when an 

electron is ejected from its orbit and expelled from the 

atom.”). It is actually a sweeping generalization to refer to all 

ionizing radiation as resulting from a single displaced 

electron. A very detailed description of the process of 
6

6

PCBs, asbestos or tobacco byproducts, we are constantly 

exposed to radiation on a daily basis. We are exposed from 

numerous natural sources including the sun,

18 or naturally 

occurring radioactive elements such as radon in the ground 

surrounding our homes.19

It is now beyond dispute that radiation can cause 

various types of cancer. However, unlike with asbestos and 

diseases, such as mesothelioma, radiation wreaks havoc with 

our bodies, not because it is a foreign substance (it is not), but 

because it transfers extra energy to our cells. This energy 

can, in turn, damage our DNA in numerous ways that are 

described in detail in TMI II.20

Asbestos fibers cause mesothelioma by damaging the 

“mesothelial cells that control cell reproduction. Some 

damaged cells die and tumor suppressor genes stop others 

 

ionization (including the all important Columb Force) can be 

found at TMI II, 193 F.3d at 632-38. 

 However, the complex distinctions are not important for 

purposes of this discussion. Therefore, rather than attempt 

more precision by distinguishing between the different types 

of ionizing particles and ionizing energy as we did in TMI II, 

we will refer to all ions as if they only consisted of electrons 

without attempting to distinguish between alpha, beta or 

gamma radiation or between orbital electrons and electrons 

created through nuclear reactions. The important thing for 

purposes of this discussion is that “[w]hen a charged particle 

passes through matter, it excites and ionizes atoms in its 

path.” Id. at 635. This is what happens to human tissue that 

is exposed to radiation. 

18 Id. at 644-47.

19 See Natural background radiation, Am. Cancer Soc’y, 

https://www.cancer.org/cancer/cancer-causes/radiationexposure/x-rays-gamma-rays/natural-backgroundradiation.html (last revised Feb. 24, 2015) (explaining that 

radon is but one source of the background radiation that we 

are potentially exposed to on a daily basis and is listed only 

for purposes of illustration).

20 See TMI II, 193 F.3d at 640.
7

from reproducing.”21 However, “[w]here suppressor genes do 

not stop the reproduction process, . . . the damaged cells 

divide, replicating the damage in the sister cells.”22 Over 

decades of continued growth of these cells, tumors develop. 

“This explains why mesothelioma has an extremely long 

latency period, as mesothelial cells have a very slow growth 

rate.”23 As expert testimony in a recent case from the 

Supreme Court of Pennsylvania established, “it is not 

scientifically possible to identify the particular exposure or

exposures that caused a patient’s mesothelioma[.] . . . 

[I]nstead, the causative agent is ‘the series of exposures.’”24

However, even though it is not possible to identify a 

particular exposure as causing a given occurrence of the 

disease, there is now no dispute that asbestos is responsible 

for mesothelioma.

Although the disease process described above for

mesothelioma is quite similar to that which is triggered by 

radiation after the cell is irradiated, there is a key difference 

that is very relevant to our discussion. As noted above, we do 

not normally develop diseases such as mesothelioma in the 

absence of exposure to the manmade carcinogens that can 

cause it. Thus, if a plaintiff can produce evidence of 

sufficient frequency, regularity, and proximity of exposure to 

asbestos to establish that it is more likely than not that that 

exposure was a substantial cause of subsequent disease, the 

plaintiff then need only prove that defendant manufactured or 

controlled the substance that plaintiff had been exposed to in 

order to recover. The same is true with any other “signature” 

disease.

Unlike products such as asbestos and PCBs, radiation 

is not a foreign substance. All of us are exposed to it every 

second of every day both inside of buildings and outdoors. 

Yet, radiation can “damage structures within the human body 

as cells are disrupted or killed by the ionizing radiation 

[energy] itself, and as energy is transferred to cells triggering

 

21 Rost, 151 A.3d at 1039 (citations omitted).

22 Id.

23 Id.

24 Id.
8

8

second-order chemical changes.”25 “Unlike a chemical 

product, which may be traceable to a particular manufacturer, 

different sources of radiation are not distinguishable, nor is 

there any noticeable difference between cancers caused by 

nuclear-power production and those caused by other sources 

of radiation.”26

[M]edical evaluation, by itself, can neither 

prove nor disprove that a specific malignancy 

was caused by a specific radiation exposure [or 

series of exposures]. Therefore, the primary 

basis to link specific cancers with specific 

radiation exposures is data that has been 

collected regarding the increased frequency of 

malignancies following exposure to ionizing 

radiation. In other words, causation can only be 

established (if at all) from epidemiological 

studies of populations exposed to ionizing 

radiation.27

However, epidemiological studies of exposed 

populations can only establish the percentage by which the 

incidence of given cancers in that population exceeds the rate 

for those same cancers in similar populations not exposed to 

the source of radiation. No study can determine whether the 

cancer of a given member of that population was the result of 

exposure to a defendant’s product or to radiation released 

from a defendant’s facility. As we explained in TMI II, “the 

task of establishing causation is greatly complicated by the 

reality that a given percentage of a defined population will 

contract cancer even absent any exposure to ionizing 

 

25 William D. O’Connell, Causation’s Nuclear Future: 

Applying Proportional Liability to the Price-Anderson Act, 64 

Duke L.J. 333, 348 (2014) [hereinafter O’Connell] (citing 

James E. Turner, Atoms, Radiation, and Radiation Protection 

421 (3d ed. 2007) [hereinafter Turner], available at 

http://nuclear.dababneh.com/Radiation-Undergrad2/Atoms,%20Radiation,%20and%20Radiation%20Protection.

pdf.

26 Id. at 350 (citing Turner at 468). 

27 TMI II, 193 F.3d at 643 (citations omitted). 
9

radiation.”28 This probability conundrum is even more of an 

issue when we try to compare members of a population who 

have only been exposed to natural radiation with members of 

the same population who have been exposed to that radiation 

plus radiation emanating from a defendant’s product or 

facility.

Plaintiffs who must prove that exposure to a particular 

source of radiation was a substantial cause of their injuries 

therefore face an insurmountable task that the law has yet to 

satisfactorily address. The task is further complicated by the 

fact that radiation includes different kinds of particles (i.e.

alpha, gamma, beta), each with different properties including 

different levels of energy and thus having a different 

capability of damaging human cells.29 As the NRC has 

explained: 

[N]atural radiation . . . is always present in the 

environment. It includes cosmic radiation which 

comes from the sun and stars, terrestrial

radiation which comes from the Earth, 

and internal radiation which exists in all living 

things. The typical average individual exposure 

in the United States from natural background 

sources is about 300 millirems per year.30

Yet, although there is general scientific agreement that 

radiation can cause cancer, we are still at the rudimentary 

stages of understanding the etiology of cancers.

31

As if this does not make plaintiffs’ task in such cases 

difficult enough, two additional considerations further 

complicate inquiries into causation. First, as has already been 

mentioned, not all radiation has the same energy level. Some 

radiation can be filtered out by barriers no more substantial 

 

28 Id. at 643-44. For a detailed explanation of the two major 

sources of natural radiation and average doses, see id. at 644-

48.

29 For a detailed discussion of this, see id.

30 U.S. Nuclear Regulatory Comm’n, Background radiation,

https://www.nrc.gov/reading-rm/basicref/glossary/background-radiation.html.

31 See TMI II, 193 F.3d at 644-48.
10 10

than sunscreen, or surface tissue, yet some radiation is 

capable of penetrating lead.32 Thus, mere proximity to a 

source of radiation does not necessarily establish a sufficient 

“absorbed dose” to link an individual’s illness to that 

proximity.

33 This point is illustrated in the extreme by the 

fact that “[c]rews of nuclear submarines have possibly the 

lowest radiation exposure of anyone, despite living within a 

few meters of a nuclear reactor, since they are exposed to less 

natural background radiation than the rest of us [(the ocean 

shelters them)], and the reactor compartment is well 

shielded.”34

Second, the difficulty of linking a potentially 

radiation-related pathology to a defendant instead of to 

background radiation is made exponentially more difficult by 

the fact that some people have a genetic predisposition to 

diseases associated with radiation exposure, while others have 

a genetic composition that seems to protect them from the 

otherwise harmful effects of radiation. Indeed, more than one 

physician has counseled that the best way to guard against 

contracting cancer is to “choose your parents carefully.”35

Genetic research has even led researchers to conclude that:

[P]erhaps a fortunate genetic endowment 

protects some lifelong smokers from lung

cancer, while a genetic mischance induces lung

cancer in some non-smokers. Both 

environmental and genetic differences between

individuals appear responsible for at least some 

 

32 See id. at 637 n.36.

33Id. at 637 (“The absorbed energy per unit mass of material 

is termed the ‘absorbed dose.’”).

34 World Nuclear Ass’n, Nuclear Radiation and Health 

Effects, http://www.world-nuclear.org/informationlibrary/safety-and-security/radiation-and-health/nuclearradiation-and-health-effects.aspx.

35 See, e.g., Huber R. Warner, If You Wish to Live a Long 

Time in Good Health, Choose Your Parents Carefully, 62A J.

of Gerontology: Biological Scis. 575 (2007), available at 

https://www.ncbi.nlm.nih.gov/pubmed/17595411; see also

Steve C. Gold, When Certainty Dissolves into Probability: A 

Legal Vision of Toxic Causation for the Post-Genomic Era, 

70 Wash. & Lee L. Rev. 237, 259 (2013) [hereinafter Gold].
11

of the variation in individuals’ responses to 

toxic exposures. For the most part, it has been 

impossible (or at least impractical) to identify, 

quantify, and tease apart these possibilities 

using the investigatory tools of toxicology, 

environmental epidemiology, conventional 

biochemistry, and classical genetics.36

Yet, Plaintiffs such as those here, must produce evidence that 

will establish that their injuries are more likely than not 

caused by effluents from Defendants’ uranium plant. I 

simply do not see any way they can do that given the current 

state of the law.

B. Congress’s Response to Causation Issues

Congress has recognized the problems inherent in 

attempting to prove causation in Public Liability Actions 

almost from the very beginning of our attempts to harness the 

power of the atom. The Atomic Energy Act of 1946 created 

the Joint Committee on Atomic Energy to correct the 

deficiencies of the Price-Anderson Act, including the 

stringent burden of establishing causation.37 The Committee 

 

36 Gold at 258-59.

37 Taylor Meehan, Lessons from the Price-Anderson Nuclear 

Industry Indemnity Act for Future Clean Energy 

Compensatory Models, 18 Conn. Ins. L.J. 339, 346 (2012)

[hereinafter Meehan]; see also Michael Flynn, A Debt Long 

Overdue, Bulletin of the Atomic Scientists 41-42 (2001) (The 

Energy Employees Occupational Illness Compensation Act 

acknowledged that “nuclear weapons workers were put at risk 

building the country’s arsenal.” Acknowledging the 

difficulties associated with establishing causation, and 

“[b]ecause the government failed to adequately track 

exposures at these sites, [the Act] assumes that workers’ 

cancers are work related, thus relieving the workers of the 

near-impossible task of having to prove the connection.” 

Further, the Act “establishes the possibility that other sites 

and illnesses may be added to the cohort at a later date.”); see 

also David Rocchio, The Price-Anderson Act: Allocation of 

the Extraordinary Risk of Nuclear Generated Electricity: A 

Model Punitive Damage Provision, 14 B.C. Envtl. Aff. L. 
12 12

was also concerned with state statutes of limitation that could 

nullify meritorious claims because of the latency of injuries 

caused by radiation.38 Consequently, the 1966 amendments 

to the Act included a provision for the waiver of various 

defenses under state tort law in the event of an “extraordinary 

nuclear occurrence.”39 An “extraordinary nuclear occurrence” 

was defined as: 

[A]ny event causing a discharge or dispersal of . 

. . byproduct material from its intended place of 

confinement in amounts offsite, . . . which the 

Nuclear Regulatory Commission or the 

Secretary of Energy. . . determines to be 

substantial, and which the Nuclear Regulatory 

Commission or the Secretary of Energy. . . 

determines has resulted or will probably result 

in substantial damages to persons offsite . . ..40

“This provision was enacted in order to assure that the 

victim’s entitlement to compensation would be determined 

under a strict liability standard, instead of the negligence 

standard that most state courts require.”41 The amendments 

also included a provision that waived state statutes of 

limitation that were more limited than the three-year limit 

established under the Price-Anderson Act.42 However, the 

overarching problem of causation was not impacted by 

attempts to augment statutes of limitation or impose strict 

 

Rev. 521, 538-39 (1987) [hereinafter Rocchio] (citing 

Hearings Before the Joint Committee on Atomic Energy on 

Proposed Amendments to the Price-Anderson Act Relating to 

Waiver of Defenses, 89th Cong., 2d Sess. 105-07 (1966), 

available at 

https://www.loc.gov/resource/conghear08.00170174379/?sp=

10). 

38 Rocchio at 539.

3942 U.S.C. § 2014(j).

40 Id.

41 Meehan at 347.

42 Id.; see 42 U.S.C. § 2210(n)(1)(F)(iii) (The Act allows “any 

issue or defense based on any statute of limitations if suit is 

instituted within three years from the date on which the 

claimant first knew, or reasonably could have known, of his 

injury or damage and the cause thereof.”).
13

liability. In either case, a plaintiff would still have to 

establish that a given pathology was caused by exposure to a 

defendant’s radiation rather than background radiation, 

heredity or some other factor. Accordingly, this legislative 

effort was only helpful in the exceedingly rare cases where 

that evidentiary gap could be bridged. 

In 1988, Congress created the Presidential 

Commission on Catastrophic Nuclear Accidents to “conduct a 

comprehensive study of appropriate means of fully 

compensating victims of a catastrophic nuclear accident that 

exceeds the aggregate public liability . . . in the statute . . . .”

43

 

In its final report to Congress, the Commission “sought to 

identify the ‘next best’ approach, since attaining the ‘best’ 

solution, compensating only those whose cancers or other 

latent illnesses were caused by the accident, is not currently 

possible.”44 The options included: 

Option A, relaxing traditional 

notions of proof of causation and 

paying something to everyone 

who gets cancer; Option B, 

retaining and rigorously applying 

traditional standards, which would 

result in paying few, if any, 

claims; and Option C, adopting 

some proxy for direct proof of 

causation, such as imputing group 

risk to individuals who actually 

develop cancer and paying those 

claims where the association 

between radiation exposure and a 

particular cancer is the strongest 

(or at least at some minimum 

level), with the option, where a 

strong association is required for a 

“full” award, of also paying lesser 

 

43 Presidential Comm’n on Catastrophic Nuclear Accidents, 

Report to the Congress from the Presidential Commission on 

Catastrophic Nuclear Accidents, Letter to the Senate (August 

1990) [hereinafter Report], available at

http://www.state.nv.us/nucwaste/news/rpccna/pcrcna02.htm. 

44 Id. at ch. 4.IV.B. 
14 14

amounts on those claims with a 

somewhat weaker association.45

The Commission ultimately recommended Option C46 and 

provided three possible ways to implement that Option, while 

noting that better techniques can be developed in the future:

47

 

The first would pay the full 

amount for any diagnosed cancer 

where the probability of causation 

(PC) is .5 or greater, and a 

declining amount down to a cutoff 

of PC = .2, at which compensation 

would be 20 percent of the full 

award, determined in accordance 

with Chapter 3.

The second variation would pay 

the full amount for any diagnosed 

cancer where the PC is .5 or 

greater, and a declining amount 

down to a PC of .2, at which 

compensation would be 30 

percent of a full award.

The third variation, which is most 

like Option A, above, would 

simply pay a benefit to anyone in 

the affected area with a diagnosed 

cancer whose radiation exposure 

indicated a PC of 20 percent or 

greater. Congress might elect to 

make this a full award determined 

in accordance with Chapter 3, or a 

fixed dollar amount, or 

reimbursement for actual medical 

expenses.48

 

45 Id.

46 This option is known as the “probability of causation” rule. 

47 Report at ch. 4.II.

48 Id. at ch. 4.IV.B. (citation omitted). 
15

Courts have adopted variations of these and other options as 

discussed below. However, despite these efforts, the problem 

of establishing causation in these suits remains because we 

continue to approach such claims the same way we approach 

injuries resulting from asbestos, defective brakes, holes in 

pavement, and falls in the aisles of the neighborhood 

supermarket. 

C. Evolving Case Law: Relaxing Standards

Some courts have responded by implementing a more 

relaxed analytical framework for these suits. None of these 

approaches has yet won general acceptance, and each 

contains certain flaws.49

1. The Preponderance Rule

The preponderance rule is very similar to the typical 

preponderance of the evidence burden. It requires a plaintiff 

to prove that the defendant’s activity was more likely than not 

either the but-for causation or a substantial factor in causing 

the plaintiff’s injuries.

50

 Courts have equated the “more 

 

49 The following discussion of evolving law is not intended as 

an exhaustive survey. Rather, I mention it only to offer 

additional examples of the problem and some solutions that 

have been suggested.

50 Shelly Brinker, Opening the Door to the Indeterminate 

Plaintiff: An Analysis of the Causation Barriers Facing 

Environmental Toxic Tort Plaintiffs, 46 UCLA L. Rev. 1289, 

1303-04 (1999) [hereinafter Brinker]; see Sterling v. Velsicol 

Chemical Corp., 855 F.2d 1188, 1201 (6th Cir. 1988)

(“Whereas numerous jurisdictions have rejected medical 

experts’ conclusions based upon a ‘probability,’ a 

‘likelihood,’ and an opinion that something is ‘more likely 

than not’ as insufficient medical proof, the Tennessee courts 

have adopted a far less stringent standard of proof and have 

required only that the plaintiffs prove a causal connection 

between their injuries and the defendant’s tortious conduct by 

a preponderance of the evidence. While, in accordance with 

Tennessee common law, plaintiffs’ proof by a reasonable 

medical certainty requires them only to establish that their 

particular injuries more likely than not were caused by 
16 16

likely than not” element of this rule to a level of certainty 

greater than 50%.51 The preponderance rule does not reduce a 

plaintiff’s burden of showing cause-in-fact, it allows the 

plaintiff to present individualized and statistical evidence to 

establish that the defendant’s activities were likely a 

substantial contributor to plaintiff’s injury.52 

Because of the 50% threshold requirement, plaintiffs 

who cannot demonstrate a greater than 50% likelihood that

the defendant caused their injuries do not recover anything. 

However, if plaintiffs are able to show, for example, that 

defendant is responsible for causing injuries to 51% of the 

exposed population, every plaintiff recovers even though the 

evidence only proved that 51% of the individuals in the 

exposed population suffered injuries because of defendant’s 

activities. 

This is basically the way causation is now determined 

in Pennsylvania, as explained in the Majority’s discussion of 

Rost v. Ford Motor Co.,

53 except that it allows group recovery 

if any group member of the group is successful in showing 

his/her disease was proximately caused (i.e. by a 51% 

probability) by a defendant.

There are several obvious problems with this 

approach. As we have explained above, because everyone in 

 

ingesting the contaminated water, their proofs may be neither 

speculative nor conjectural.”).

51 In re Agent Orange Prod. Liab. Litig., 597 F. Supp. 740, 

835-37 (E.D.N.Y. 1984), aff’d sub nom. In re Agent Orange 

Prod. Liab. Litig. MDL No. 381, 818 F.2d 145 (2d Cir. 1987)

(quoting Jackson v. Johns-Manville Sales Corp., 727 F.2d 

506, 516 (5th Cir. 1984), on reh'g, 750 F.2d 1314 (5th Cir. 

1985)) (The rule provides an “‘all or nothing’ approach, 

whereby [assuming all other elements of the cause of action 

are proven], the plaintiff becomes entitled to full 

compensation for those . . . damages that are proved to be 

‘probable’ (a greater than 50 percent chance), but is not 

entitled to any compensation if the proof does not establish a 

greater than 50 percent chance.”).

52 Id. at 835.

53 See Maj. Op. at 49-52 (citing Rost, 151 A.3d 1032). 
17

the population will have been exposed to radiation during 

their lifetime, and since it is not yet possible to isolate the 

effect of radiation from a particular source, the same 

problems of causation remain. This approach merely 

suspends proof of causation for everyone else if anyone in the 

group can prove causation. All recover based on the showing 

that someone should recover. However the nearly impossible 

burden of proving causation remains. Moreover, if the 

burden can somehow be satisfied by any one plaintiff or a 

subset of plaintiffs, the result imposes “crushing liability” on 

defendants that could negatively impact some efforts to find 

alternative energy sources.

54 In addition, this approach 

allows plaintiffs whose injury is probably genetic or due to 

background radiation to recover along with those who can 

trace their injury to the disputed source. But, the fact that one 

or more plaintiffs in a given population have been injured by 

exposure to a given source certainly does not mean that 

everyone in that population has been. Yet, everyone would 

ride along on the claims of those who can show a defendant 

proximately caused his/her injury. 

2. The Proportionality Rule

Alternatively, some courts have used the 

proportionality rule. This rule presumes causation when a 

plaintiff presents statistical evidence showing that it is likely 

that a defendant’s activities caused an injury to a proportion 

of the individuals in the exposed population.55 This approach 

may, at first, also appear to resemble Pennsylvania’s 

“frequency, regularity and proximity” test. However, under a 

pure implementation of this proportionality rule, plaintiffs are 

not required to present individualized proof. For example, if 

100 plaintiffs alleged that defendant’s disposal of hazardous 

wastes caused their injury and the risk of developing such 

injury in the exposed population is 55%, then every plaintiff 

will recover 55%.56 However, plaintiffs will likely never 

 

54 Brinker at 1309-10.

55 Id. at 1313. 

56 Sindell v. Abbott Labs., 607 P.2d 924, 937 (Cal. 1980); see 

Cottle v. Superior Court, 5 Cal. Rptr. 2d 882, 905 (Ct. App. 

1992) (Johnson, J., dissenting) (“Instead of choosing between 

the extremes of overcompensation and no compensation at all 
18 18

obtain complete recovery under such a tort regime.

57 In 

addition, this rule still allows plaintiffs whose injuries or 

deaths were likely attributable primarily to background 

radiation or genetics (or a combination of the two) to recover. 

3. The Allen Rule

The United States District Court for the District of Utah 

presented another option in Allen v. United States, which 

involved a dispute arising from atmospheric testing. That 

court resorted to burden shifting. A rebuttable presumption of 

liability arises if a plaintiff can show a correlation between 

his or her injuries and the increased risk resulting from a 

defendant’s negligent release of radiation. The problem here 

is that correlation is not the same as causation.58 Yet, using 

this approach, Allen held that

[w]here a defendant who negligently creates a

radiological hazard which puts an identifiable 

population group at increased risk, and a 

member of that group at risk develops a 

biological condition which is consistent with 

having been caused by the hazard to which he 

has been negligently subjected, such 

consistency having been demonstrated by 

 

this solution allows plaintiffs to recover a percentage of their 

damages from those responsible for their exposure to the 

toxic. Under this formula defendants responsible for the toxic 

exposure are liable to all those who were exposed and later 

suffered injury—including those who may have suffered the 

injury even if they had never come near the toxic 

substance. But defendants are only liable for a percentage of 

plaintiffs’ damages equal to the degree this exposure 

increased plaintiffs’ risk of injury. For example, assume a 

chemical increases the risk of cancer by 15 percent among 

those exposed to the toxin. All exposed to this chemical who 

later came down with cancer would be entitled to recover 15 

percent of their total damages from those responsible for the 

exposure.”).

57 Brinker at 1318 (citation omitted). 

58 For example, the height of males and females correlates to 

whether they play professional basketball. However, playing 

professional basketball does not cause players to grow taller. 
19

substantial, appropriate, persuasive and

connecting factors, a fact finder may reasonably 

conclude that the hazard caused the condition 

absent persuasive proof to the contrary offered 

by the defendant.59

In undertaking this inquiry, the fact finder considers 

the following non-exhaustive list of factors:

(1) the probability that plaintiff was exposed to 

ionizing radiation due to nuclear fallout from 

atmospheric testing at the . . . Test Site at rates 

in excess of natural background radiation; (2) 

that plaintiff's injury is of a type consistent with 

those known to be caused by exposure to 

radiation; and (3) that plaintiff resided in 

geographical proximity to the . . . Test Site . . . . 

Other factual connections may include but are 

not limited to such things as time and extent of 

exposure to fallout, radiation sensitivity factors 

such as age or special sensitivities of the 

afflicted organ or tissue, retroactive internal or 

external dose estimation by current researchers, 

a latency period consistent with a radiation 

etiology, or an observed statistical incidence of 

the alleged injury greater than the expected 

incidence in the same population.60

 

59 Allen v. United States, 588 F. Supp. 247, 415 (D. Utah 

1984), rev’d on other grounds, 816 F.2d 1417 (10th Cir. 

1987).

60 Id.; see also Restatement (Second) of Torts § 433 (1965)

(“The following considerations are in themselves or in 

combination with one another important in determining 

whether the [defendant’s] conduct is a substantial factor in 

bringing about harm to another: (a) the number of other 

factors which contribute in producing the harm and the extent 

of the effect which they have in producing it; (b) whether the 

actor’s conduct has created a force or series of forces which 

are in continuous and active operation up to the time of the 

harm, or has created a situation harmless unless acted upon by 

other forces for which the actor is not responsible; (c) lapse of 

time.”); see also O’Connell (proposing a species of 

proportionality tests that allows compensation based upon 
20 20

The problem here is that because this rule presents several 

factors that courts can consider, consistency may be elusive 

and courts addressing substantially identical circumstances 

may reach different results. Nevertheless, this approach 

appears to be the most promising and the most consistent with 

the realities of the risk created by an activity that can expose a 

population to radiation. It may be that the only realistic 

approach is to compensate an identified population for the 

increased risk occasioned by a given activity. I do not, 

however, suggest that such nagging questions as the amount 

of that compensation, identifying the population that is at 

increased risk, or countless other factors lend themselves to 

easy or equitable resolution.

None of these approaches have yet gained wide 

acceptance and, as should be evident from this discussion, 

none of these approaches is close to perfect. Rather, they are 

sorely needed attempts to adopt (or augment) the traditional 

rules requiring a direct and linear cause-in-fact relationship 

with no intervening causes, to the reality of exposure to 

ionizing radiation resulting from human activities. 

III. CONCLUSION

For reasons I have explained, my concerns about some 

of the District Court’s rulings are not sufficient to cause me to 

conclude that the court erred in granting summary judgment 

against these Plaintiffs and dismissing the complaint. 

Problems with the Plaintiffs’ proof (and lack thereof) and the 

Herculean task of trying to produce enough evidence to get to 

a fact finder on the issue of causation are simply too 

formidable for these claims to survive. 

As I have explained, this will almost always be the 

case until state supreme courts, state legislatures and/or 

Congress devise a way to more fairly address the very real 

and substantial dangers posed by activities that increase the 

risk of exposing communities to ionizing radiation. However, 

 

increased risk once that risk exceeds a certain threshold. The 

threshold is, of course, a policy matter and can be determined 

by legislatures after hearings on this issue.).
21

since that day is not yet here, I agree that Defendants were 

entitled to summary judgment. I can only hope that the dues 

that we pay for the comforts of living in the atomic age will 

one day not require us to forego remedies for the harmful 

effects of the nuclear byproducts of that modernization, which 

we are still trying to understand.