Michael Anthony Debiec, Administrator of the Estate of Jane Louise Guldin Debiec, Deceased v. Cabot Corporation, Individually and as Successor in Interest to Cabot Berylco, Inc., Kawecki Berylco Inc., A/K/A Kbi Kawecki Berylco Industries, Inc. & the Beryllium Corporation Ngk Metals Corp., Individually and as Successor to the Beryllium Corporation, Kawecki Berylco Inc., A/K/A Kbi, Kawecki Chemical Co., & Berylco, Inc., Michael Anthony Debiec, Sharon J. Reeser, Administratrix of the Estate of Geneva C. Bare, Deceased v. Cabot Corporation, Individually and as Successor in Interest to Cabot Berylco, Inc., Kawecki Berylco Inc., A/K/A Kbi Kawecki Berylco Industries, Inc., the Beryllium Corporation Ngk Metals Corporation, Individually and as Successor to the Beryllium Corporation, Kawecki Berylco Inc., A/K/A Kbi, Kawecki Chemical Co. Berylco, Inc., Sharon J. Reeser, Dennis J. Branco, Personal Representation of the Estate of John C. Branco, Deceased v. Cabot Corporation, Individually and as Successor in Interest to Cabot Berylco, Inc., Kawecki Berylco Inc., A/K/A Kbi Kawecki Berylco Industries, Inc., the Beryllium Corporation Ngk Metals Corp, Individually and as Successor to the Beryllium Corporation, Kawecki Berylco Inc., A/K/A Kbi, Kawecki Chemical Co., Berylco, Inc Brush Wellman Inc., Dennis J. Branco, Mary I. Russo Charles F. Russo, H/h v. Cabot Corporation, Individually and as Successor in Interest to Cabot Berylco, Inc., Kawecki Berylco Inc. A/K/A Kbi Kawecki Berylco Industries, Inc. & the Beryllium Corporation, C/o C.T. Corporation System Ngk Metals Corporation, Individually and as Successor to the Beryllium Corporation, Kawecki Berylco Inc., A/K/A Berylco, Inc., C/o C.T. Corporation System Mary I. Russo Charles F. Russo, H/h

These personal injury and wrongful death cases, consolidated for discovery in the District Court and for disposition in this Court, stem from the deaths of four people, all of whom worked at and/or lived near the defendants' beryllium plant in Reading, Pennsylvania. Each of the deaths was traceable to Chronic Beryllium Disease ("CBD"), a result of exposure to that toxin, and the victims either brought or had brought on their behalf suits against the Cabot Corporation ("Cabot") and the NGK Metals Corporation ("NGK Metals").

Finding that Pennsylvania's two year statute of limitations had run on the plaintiffs' claims, the District Court granted summary judgment to the defendants and denied plaintiffs' motion for reconsideration. In so doing, the Court rejected plaintiffs' argument that the statute was tolled under the "discovery rule," which protects plaintiffs in circumstances in which, through no fault of their own, they do not discover their injury until after the statutory period would normally have ended. The plaintiffs argued that, as required by Pennsylvania law, they had each brought suit within two years of the date when they knew, or should have known, that their disease was beryllium-related. The defendants asserted, however, that the point at which these plaintiffs could have determined that their conditions were traceable to beryllium exposure, had they diligently investigated that possibility, occurred more than two years before each filed suit.

Concurring with the defendants, the District Court concluded that no reasonable person could find that any of these plaintiffs had exercised the "due diligence" in investigating their physical conditions required in order to avail themselves of the protections of the discovery rule, and that therefore the question whether the statute had run, usually a question for the jury, need not go to one. We disagree as to Jane Debiec, Mary Russo, and Geneva Bare. Based on the specific facts of each of these three cases, we conclude that reasonable minds could find that each of the decedents exercised due diligence in investigating her condition, and therefore the question whether the statute of limitations had run on their claims should have gone to a jury. The judgments of the District Court will be reversed as to Debiec, Russo, and Reeser, and their cases will be remanded for further proceedings. We conclude, however, that the fourth plaintiff, John Branco, failed to exercise due diligence, and we will therefore affirm the District Court's dismissal of his claim as time-barred.

Defendants Cabot and NGK Metals operate a beryllium manufacturing facility in Reading. They are successors to Kawecki Berylco Inc., which operated the facility for many decades. Beryllium is a lightweight, high strength, tensile metal with a variety of industrial uses. It is also a toxic substance that can cause both cancer and a chronic scarring lung disease — CBD. The decedents in these cases spent much of their lives working and/or residing in close proximity to the plant, and each contracted CBD. Because the specific facts of each plaintiff's case are critical for determining whether the statute of limitations has run, we relate these facts in some detail.

Jane Debiec ("Debiec") died in April 2000 at the age of 57. Her autopsy showed that the cause of death of was CBD. Her husband, Michael Debiec, filed personal injury and wrongful death claims in May 2001. From 1943 to 1961, as a child and youth, Debiec lived a mile or less from the defendants' plant. She began to have respiratory symptoms during her first pregnancy in 1976 and the symptoms recurred during her second pregnancy in 1978. At that point Debiec sought the advice of Dr. John Shuman, who recommended a lung biopsy. The biopsy revealed "granulomatous lung disease with significant fibrosis" and also detected 6.5 micrograms of beryllium per gram of dried tissue. Shuman's conclusion on the basis of this test was that Debiec was suffering from sarcoidosis, a granulotomous lung disease of unknown cause or origin.

When asked about the significance of the 6.5 micrograms of beryllium per gram of dried tissue found in Debiec's biopsy, Shuman testified "[i]t means there was not very much beryllium in the tissue.... Had there been a significant amount of beryllium in the tissue, I think one would certainly have to consider beryllium-induced lung disease. The fact that there wasn't any doesn't-did not mean that that wasn't a possibility, but it simply wasn't supportive of that. My clinical impression was otherwise and there just wasn't a reason to change it." SA at 525.

In 1980, the Debiecs told Dr. Shuman that they believed her illness might be related to exposure to zirconium. The parties dispute the meaning of the notes Shuman took on the Debiecs' 1980 visits; Debiec suggests that the notes demonstrate that he and his wife were concerned only about zirconium at that time, while the defendants argue that the Debiecs were already considering litigation against the plant at that point and make much of the fact that Shuman recommended that they get a second opinion from one Dr. Israel, who was the "closest, most internationally known, expert on sarcoid." SA at 527. These notes are important, so we rescribe them at length:

Her husband came in with her and I told them I have not come across any useful information regarding zirconium or talked to anyone who seemed to know very much about it. Mr. Debiec came armed with two publications from the Federal Register, issued from the Department of Health Education and Welfare. He has a number of lines underlined, which in reading areas that are not outlined, has the proverbial effect of lifting things out of context. One of the areas not underlined, for example, was "regulatory action was being taken with respect to cosmetic products based upon the lack of toxological data adequate to establish a safe level for use...." I talked with Dr. Lane who determined that the entire biopsy block had been sent to Kemron Environmental Services for silica, asbestos, and beryllium exposure. Only beryllium was tested... because of the small sample. Relevant to these other problems, Jane mentioned that she had previously lived in an area near Kawecki. As far as I am concerned at this time, there seems to be little reason to alter her clinical diagnosis of sarcoidosis. Under the circumstances, I will encourage her to perhaps, see Dr. Israel.... The evidence for zirconium-induced granulomas appears to be weak, although I could not deny the possibility. It seems unlikely that anything definitive will be able to be shown here. While Jane states that there is [not] any thought of litigation involved, I am rather skeptical about that. It would not surprise me to receive a legalized complaint in the future about our failure to analyze the biopsy for zirconium.

I explained to her that her biopsy block was sent off for analysis for asbestos, silica, and beryllium, but [sic] was insufficient slides for all these tests. Following conversation with somebody, the beryllium study was done. Short of another biopsy, we cannot test for zirconium. She is more interested in having her symptoms treated than whether or not the problem was from zirconium since if it were so, the exposure doesn't exist anymore; and her treatment would not change and her symptoms would not behave differently if she knew that. Her husband, on the other hand, was somewhat disturbed at my answers ... and, apparently did not feel he got a fair shake on his questions about zirconium. I, again, suggested to her that for peace of mind, it may be worthwhile, her seeing Dr. Israel to find out what he thinks about this possibility.

SA at 17-18.

We read these notes to mean several things. First, the Debiecs' (especially Mr. Debiec's) real concern in 1980 was zirconium, not beryllium. Second, Shuman was suggesting that Debiec see Dr. Israel about the possibility that zirconium, not beryllium, was causing her symptoms.1 Third, the litigation Shuman was talking about was potential litigation against him and his group, not against the defendants in this case.

This last conclusion is arguably thrown into some doubt by Shuman's deposition, which included the following colloquy between Dr. Shuman and NGK Metal's attorney:

Q. And what litigation were you thinking about when you said that?

A. I mentioned in the same paragraph there, apparently, was some suspicion about where she had lived, that is, in the neighborhood of this Kawecki-Berylco at the time, so I guess that issue had arisen....

Q. Looking at the August 26th, 1980 note, I see down at the bottom of that, the last sentence of that note, it says, quote, it would not surprise me to receive a legalized complaint in the future about our failure to analyze a biopsy for zirconium, period, closed quote. When you — what are you talking about when you — in that sentence? What does that mean?

A. Mr. Debiec is very persistent and I thought he may — would probably — I thought he might take one of his questions and just, you know, push it to this extent.

Q. Meaning filing a complaint against you and the group?

A. I guess that's what I — well, I guess I'm not sure who it would be directed against.

SA at 528.

We conclude that despite Shuman's initial assertion during his deposition that his notes meant that the Debiecs were considering filing a lawsuit against the defendants in 1980, those notes were referring to litigation that might be brought against him and his group.

The defendants draw our attention to a number of other events and facts that they argue have significance. For example, they point out that while at Penn State in 1990, Mr. Debiec's brother John wrote a research paper which discussed the possibility of a link between sarcoidosis and beryllium exposure, and which relied on a discussion of Jane Debiec's case. John Debiec testified that when he wrote that paper, he believed that Mrs. Debiec's condition was caused by beryllium. The defendants also point to a letter from a Colonel George W. Ward of the Army Medical Department that was attached to the paper. The letter stated that "Sarcoidosis is a non specific chronic granulomatous tissue response. Therefore, it is likely that there are many causes which can produce such non specific tissue response. One known cause is beryllium. Whether other elements such as zirconium and aluminum can also cause this is speculative at this point." SA at 118.

Defendants also point to a 1992 Environmental Protection Agency ("EPA") public meeting in (nearby) Muhlenberg, Pennsylvania regarding the Reading plant. Michael Debiec spoke at that meeting and stated that "... I have been doing research on this for many years because my wife is seriously ill with a disease called sarcoidosis. And she lived in [nearby] Temple. And I done research for ten years, and I found out through different doctors that there's only one known cause of Sarcoidosis and pulmonary interstitialitis. And that comes from Beryllium." SA at 201. Mr. Debiec testified that after the meeting his wife told him that he was "crazy" for pursuing the idea that she may have had berylliosis. In response to defense counsel's question "Did you believe that her illness proved that breathing beryllium oxide was hazardous?", Mr. Debiec testified "I may have suspected it lightly, but that was only in the beginning. Later I did not. Once I talked to Dr. Shuman and he was emphatic. Whatever I did I did on my own." SA at 514-515.

In October of 1993, Mr. Debiec wrote to the Agency for Toxic Substances and Disease Registry ("ATSDR") and professed disappointment at the agency's handling of its study of the Reading plant. He wrote:

I'm appalled and shocked that your investigative team could not come up with any other residents who are suffering from Beryllium related illnesses or who may have died as a result of Beryllium poisoning.... I'm tired of relating my wife's case to prove breathing beryllium oxide is extremely hazardous to one's health. She lived half a mile from the NGK plant on dry dirt. At the age of thirty-four she has one-third breathing capacity compared to a normal adult. A biopsy of her lungs shows that she has Beryllium in her lungs.... According to Dr. Lee Newman, an occupational medicine specialist at the National Jewish Center for Immunology and Respiratory Medicine, a very minute amount of Beryllium can cause the disease.

SA at 258-59.

The ATSDR's final report on the Reading plant was issued in June 1995. The report noted that some community residents were concerned that people "living in the Reading area may develop sarcoidosis from exposure to beryllium oxide." SA at 274. The report also observed that:

Diagnosed cases of both acute and chronic beryllium disease have been extremely rare in recent decades. As of 1983, no cases of occupational berylliosis had been reported among individuals first exposed after 1973. With only one exception, no cases of CBD have been reported from indirect or nonoccupational exposure among individuals whose exposure began after about 1950. However, since CBD mimics the symptoms of sarcoidosis and may readily be confused with the latter disease, it is possible that additional, undiagnosed cases of CBD, masquerading as sarcoidosis, have occurred.

SA at 295.

The report concluded that while concentrations of beryllium had at times exceeded recommended levels near the plant, there was little public health hazard. It cautioned, however, that:

if any adverse health effects occurred in response to higher off-site exposures in the past, they would probably be limited to CBD in a sensitive (i.e. immunologically predisposed) subpopulation living near the site. Since any past cases of nonoccupational CBD would likely have been misdiagnosed as sarcoidosis, long-term residents who have been exposed to clinically significant levels of beryllium in the past may want to consider consulting an occupational/environmental medicine specialist who can determine whether specialized testing for beryllium sensitivity is appropriate.

SA at 296.

Dr. Shuman did not alter his diagnosis of Debiec's condition, that she had sarcoidosis not CBD, during her lifetime. However, an April 2000 post-mortem diagnosis, made under the Case Registry of Chronic Beryllium Disease, determined that Debiec had been suffering from CBD. Mr. Debiec filed suit in May 2001.

Plaintiffs Mary and Charles Russo filed their action on May 24, 2001, alleging that Mrs. Russo ("Russo") had been diagnosed with CBD on June 25, 1999. Russo died on February 5, 2002; her death certificate identified the causes of death as respiratory failure, pulmonary fibrosis, and CBD.

Russo had worked at the defendants' beryllium plant in an office job, not in the actual plant itself, for between 18 and 20 months spanning the years 1946-48. After a month on the job, she developed breathing troubles. Her family doctor ordered her to stay at home for a thirty day period while he tried to determine the source of her difficulties. She later returned to work at a different part of the complex. After leaving her job at the plant, Russo lived and worked within miles of the plant for half a century.

In 1993, a routine examination determined that Russo had "[c]hronic interstitial fibrotic appearing changes ... in both upper lungs. These are not changed appreciably from old films. The lower lungs show some very mild chronic interstitial disease." SA at 3. In February 1998, Russo underwent an examination by pulmonologist Dr. Richard Bell, who was aware that Russo had worked at the beryllium plant in the 1940s. His diagnosis stated that "I feel that the patient has an idiopathic pulmonary fibrosis. I do not believe it is related to the beryllium employment." App. at 76. Two weeks later, Russo contacted Dr. Bell again to ask if her lung condition might be related to breast cancer that had manifested itself in 1995. Dr. Bell told her that this was improbable and restated his view that "it was highly unlikely that this was related to her beryllium exposure approximately five (5) decades prior." SA at 77.

Russo testified that she was dissatisfied with her visit to Dr. Bell, and that "when I mentioned that I worked at Beryllium, there was a question in my mind now, because in the local papers they were having all different kind of articles coming up telling us about people that worked at Beryllium and years later developing these symptoms." SA at 73-74. Russo went on to say that:

So, when I told Dr. Bell this, what I thought, he said to me, It's so long ago, Mary. He says it can't be that or something to that effect cause that is a long stretch. But I wasn't happy with that. It bothered me because I heard people that didn't even work there had this. They didn't even have to work at the plant.

SA at 74. During her recovery from knee surgery in April 1998, Russo's lung condition worsened. On April 10, she had a 30 to 40 minute coughing attack and was admitted to the hospital for a week. During this hospitalization, Russo began treatment with a new doctor in Bell's group — Dr. Mengel. However, Russo's lung condition worsened throughout 1998 and by November of that year she required portable oxygen. Dr. Mengel testified that when he discovered that Russo had worked at the beryllium plant, it "rais[ed] an alternative diagnosis to idiopathic pulmonary fibrosis" and he considered the possibility that Russo had CBD. SA at 133. He also testified, however, that he did not change the diagnosis at that point because he "didn't have any evidence yet." Id. Dr. Mengel recalled that he had wanted to have a lung biopsy done on Russo for diagnostic purposes, but that she was so ill he feared it would have killed her. SA at 136.

The defendants point out that Russo began to collect newspaper articles on CBD "at some point" after her February 1998 visit to Dr. Bell. The articles they refer to were from the March 29 and April 12, 1999 Reading Eagle. The defendants also stress the fact that Russo asked both Dr. Bell and Dr. Mengel about the possibility that she had gotten sick as a result of her proximity to the Reading plant. Russo argues that it was as a result of reading the newspaper articles that she requested a beryllium lymphocyte proliferation test ("BeLPT"), the results of which became available on June 25, 1999 and confirmed that she had CBD.2 The idea to take the test was her own. None of her doctors raised the possibility that her condition was related to her employment at the beryllium plant some half century earlier. Dr. Mengel altered his diagnosis from idiopathic pulminary fibrosis to CBD only after the results of the BeLPT came back positive. He testified that this new diagnosis was based "primarily" on these results, and only "secondarily" on the fact that Russo had worked in and lived near the Reading plant. SA at 136, 138.

C. Sharon Reeser (Administratrix of the Estate of Geneva Bare)

Sharon Reeser brought her personal injury and wrongful death claims on June 6, 2001 as the administratrix of the estate of her mother, Geneva Bare, who died in November 2000 of CBD. Bare lived within two blocks of the Reading plant throughout most of her life. She began to experience difficulty with her lungs in the early 1990s, at which point she came under the care of a pulmonologist, Dr. Krol. One of Bare's daughters, Judith Forry, testified that she accompanied her mother to a doctor's appointment in the mid or late 1990s (she was unsure of the date and if the appointment was with Dr. Krol or with a Dr. Muvdi) and that her mother asked if berylliosis was a possibility, but that the doctor "really kind of put it off. He really didn't think it was important to her case. He said the test wasn't really accurate." SA at 199. Forry testified that her mother's question had been prompted by an article on berylliosis in the Reading Eagle, but that this was the first and only time Bare raised the issue of berylliosis until shortly before she died, when Bare was reminded of the possible link between beryllium exposure and lung disease by hearing that a neighbor had been diagnosed with CBD. SA at 200.

In their personal notes on her case, Bare's physicians raised the possibility that she had berylliosis. In 1996, for example, Dr. Krol wrote a letter to another of Bare's physicians stating that she:

certainly has progressive interstitial lung disease and had significant interstitial lung disease as far back as 1977.... I don't know the cause of her interstitial disease. It certainly could be a form of idiopathic pulmonary fibrosis, berylliosis, sarcoidosis, even bronchiectasis....

SA at 5. In an earlier letter regarding Bare, Dr. Krol had noted her "exposures at the beryllium plant," SA at 3, and in his January 1997 record of Bare's condition, he wrote that she had "[s]table pulmonary fibrosis since 1977" and that "[i]t has been slowly progressive[,] question of berylliosis." SA at 8. In July 1997, Dr. Krol again noted that Bare suffered from "Interstitial lung disease, possible berylliosis." SA at 8.

In response to an inquiry about the "question of berylliosis" language in Dr. Krol's January notes, Judith Forry testified that "Dr. Krol never recommended it could be [berylliosis]. That would be my mother's guess.... That would probably be my mother questioning him." SA at 208. A Dr. Stelmach also took notes on Bare's condition, in February 1999, and stated that she had a "longstanding history of interstitial lung disease and pulmonary fibrosis of undetermined etiology, although there is a very weak suggestion it is related to beryllium exposure, in that she lived in the area of the beryllium factory." App. at 108.

While it is clear that Bare's physicians thought berylliosis might be a possibility, Reeser testified that they never shared this with Bare herself. When asked if Dr. Krol or any other doctor had informed Bare of the possibility that her condition might be linked to her exposure to beryllium, she responded "my goodness, no." App. 110-111. Reeser asserts that she herself first became aware of the potential connection between her mother's illness and beryllium exposure in 2000, when one of her neighbors was diagnosed with CBD. App. 114-115. The presence of CBD was first confirmed during Bare's autopsy.

John Branco ("Branco") worked at the Reading plant for 33 years and lived within a mile of the plant for most of his life. He died of lung fibrosis due to CBD in June of 1999.

In 1995, Branco began to have difficulty with his breathing, incident to exertion. In June of that year, he received a letter from the Department of Health and Human Services ("HHS"), apprising him of a study the Department had conducted on the health of workers exposed to beryllium. The letter stated that:

Before this study began, we knew that people exposed to beryllium may develop two forms of beryllium disease, acute and chronic. These are lung diseases caused by exposure to beryllium.... Our study, however focused on lung cancer. Some studies had linked lung cancer to beryllium exposure. However, this link was uncertain.... We found an increased risk of lung cancer in workers exposed to beryllium at all plants combined.... Chronic Beryllium disease and lung cancer may develop many years after the last exposure to beryllium. Thus, you and your doctor should be aware that you might have an increased risk of developing these diseases.... If you have lung or breathing problems that don't go away, see your doctor.

SA at 40-42. (Emphasis in original).

In February 1997, Branco received a chest x-ray, which revealed the presence of interstitial lung disease, the "etiology of" which was "uncertain." SA at 3. In May of 1997, Branco had cardiac bypass surgery. During his recovery, one of his cardiologists, Dr. Feater, noted that Branco "has had a chronic history of shortness of breath secondary to his berylliosis." SA at 10. In early August 1997, a second cardiologist, Dr. Politzer, wrote to Branco's personal physician advising him of Branco's condition, and stated that "the patient was felt to have respiratory failure secondary to chronic interstitial fibrosis which is most likely secondary to berylliosis, given the patient's thirty-five year work history with American Beryllium." SA at 17. Branco was referred to a pulmonologist, Dr. Mariglio, in August 1997. At this point, both Branco and Dr. Mariglio were suspicious about a potential link between Branco's condition and his exposure to beryllium. As a result, Dr. Mariglio referred Branco to Dr. Rossman, a berylliosis expert at the Hospital of the University of Pennsylvania.

In his letter to the University of Pennsylvania doctors, Dr. Mariglio wrote that his "Impression" was that Branco had "progressive Interstitial Lung Disease with respiratory failure most likely berylliosis, rule out other forms Interstitial Lung Disease." On September 15, 1997, Dr. Mariglio wrote to Branco's personal physician that "due to his previous exposure to berylliosis, the most likely culprit initiating his Interstitial Lung Disease remains beryllium exposure." Dr. Rossman took x-rays and performed a BeLPT and a bronchoscopy with bronchoalveolar lavage ("BAL"). Neither the BeLPT, nor the BAL showed any evidence of response to beryllium. In his letter to Dr. Mariglio about these tests, Dr. Rossman wrote:

As you can see from the enclosed results, there was no significant proliferation of either his blood or lung cells to beryllium sulfate or beryllium fluoride. Of note, the positive controls of the lung cells did not respond to the mitogens, PHA and Con A, or to the recall antigen, Candida, and therefore this is a technically unsatisfactory study. Transbronchial biopsy showed only mild chronic inflammation. Thus, these studies cannot confirm evidence of chronic beryllium disease being the cause of Mr. Branco's interstitial lung disease. Other causes must be considered such as bronchiolitis obliterans or idiopathic pulmonary fibrosis. It is recommended that Mr. Branco have a repeat bronchoalveolar lavage to definitively rule out beryllium disease since the lung proliferative results were technically unsatisfactory though negative.

App. at 96-97. Upon receipt of this letter, Dr. Mariglio called Branco and told him that "[h]is lymphocyte proliferation studies were negative for evidence of beryllium related disease" and that "[w]e will treat [you] as IPF." App. at 104. The testing process was physically debilitating for Branco, causing "deterioration ... such that [] he developed increasing hypoxemia and required an overnight admission to the Hospital of the University of Pennsylvania." App. at 105. Already quite ill at that point, Branco made it clear that he did not want to undergo another round of tests with Dr. Rossman. App. at 105.

As a result of Branco's visit to Dr. Rossman, the Branco family's fear that his condition was beryllium-related evaporated. When asked whether Rossman's examination had an effect on his thinking, Dennis Branco, the decedent's son, testified "Oh, yes. I didn't think he had berylliosis then." App. at 93-94.

We confront the question whether, given each plaintiff's specific history, the District Court properly found that their causes of action were barred by the statute of limitations.3 Because "state tolling principles are generally to be used by a federal court when it is applying a state limitations period," Vernau v. Vic's Market, Inc., 896 F.2d 43, 45 (3d Cir.1990), in this diversity action we look to Pennsylvania law and predict how the Pennsylvania Supreme Court would decide this case. See Bohus v. Beloff, 950 F.2d 919, 924 (3d Cir.1991).

Pennsylvania has a two year statute of limitations for personal injury and wrongful death actions. 42 Pa. Cons. Stat. § 5524(2). The question before us is, at what point did the plaintiffs' claims accrue? Generally, a claim accrues "as soon as the right to institute and maintain a suit arises," Pocono Int'l Raceway, Inc. v. Pocono Produce, Inc., 503 Pa. 80, 468 A.2d 468, 471 (1983), which, in most tort actions, is at the moment the injury is sustained. In order to "`ameliorate the sometimes harsh effects' of the statute of limitations," however, Pennsylvania courts have crafted an exception to this rule for situations in which a party, through no fault of his or her own, does not discover her injury until after the statute of limitations normally would have run. Bohus, 950 F.2d at 924 (quoting Cathcart v. Keene Indus. Insulation, 324 Pa.Super. 123, 471 A.2d 493, 500 (1984)). Latent disease cases often implicate this so-called "discovery rule," which tolls the statute. In this type of case, "the statute of limitations begins to run ... when the plaintiff knows, or reasonably should know: (1) that he has been injured, and (2) that his injury has been caused by another party's conduct." Cathcart, 471 A.2d at 500. The burden is on the party claiming the benefit of the discovery rule to prove that she falls within it. Dalrymple v. Brown, 549 Pa. 217, 701 A.2d 164, 167 (1997); Cochran v. GAF Corp., 542 Pa. 210, 666 A.2d 245, 249 (1995).

In order to take advantage of the discovery rule, a plaintiff must have exercised "due diligence" in investigating her physical condition. Bohus, 950 F.2d at 924. We have explained that "[t]he `polestar' of the discovery rule is not the plaintiff's actual knowledge, but rather `whether the knowledge was known, or through the exercise of diligence, knowable to [the] plaintiff.'" Id. at 925 (quoting O'Brien v. Eli Lilly & Co., 668 F.2d 704, 711 (3d Cir.1981)). The Pennsylvania Supreme Court has described the required diligence in this setting as follows:

Reasonable diligence is just that, a reasonable effort to discover the cause of an injury under the facts and circumstances present in the case. Long ago we recognized that there are few facts which diligence cannot discover, but there must be some reason to awaken inquiry and direct diligence in the channel in which it would be successful. This is what is meant by reasonable diligence.

Cochran, 666 A.2d at 249 (quotation marks omitted). The Court stressed that:

[r]easonable diligence is an objective, rather than a subjective standard. Under this standard, the plaintiff's actions must be evaluated to determine whether he exhibited those qualities of attention, knowledge, intelligence and judgment which society requires of its members for the protection of their own interests and the interests of others.

Id. (quotation marks omitted).

In sum, the statutory time period begins to run in latent disease cases at the moment at which the plaintiffs possessed "sufficient critical facts to put [them] on notice that a wrong has been committed and that [they] need investigate to determine whether [they were] entitled to redress." Zeleznik v. United States, 770 F.2d 20, 23 (3d Cir.1985).

In Bohus, we held that "[t]he question whether a plaintiff has exercised reasonable diligence is usually a jury question." 950 F.2d at 925. The Pennsylvania Supreme Court has cautioned, however, that while this question is "usually for the jury,.... [w]e also recognize the well established principle that where the facts are so clear that reasonable minds cannot differ, the commencement period may be determined as a matter of law." Cochran, 666 A.2d at 248.

While the parties agree on these basic legal standards, they disagree about how to apply them in this case and, more specifically, about how to measure the impact of a professional medical diagnosis on a court's evaluation of whether a plaintiff has exercised reasonable diligence in investigating her condition. This is an important issue here, because at some point doctors told each of the plaintiffs that it was unlikely they were suffering from CBD.

In support of their argument that the plaintiffs exercised reasonable diligence in these cases, Debiec et al. rely on a line of Pennsylvania cases, starting with Trieschock v. Owens Corning, 354 Pa.Super. 263, 511 A.2d 863 (1986), that stands for the proposition that in determining when the statute of limitations begins to run, a plaintiff cannot be charged with having more information than his doctors have about his condition. The defendants counter that Trieschock and its progeny are no longer good law.

Trieschock involved a diagnosis of asbestosis. After a screening of employee medical results in March 1982, an Owens-Corning doctor informed Trieschock that he suspected he had asbestosis and that he had scheduled an appointment for him to see a pulmonary specialist. Trieschock saw the specialist on April 8, 1982 and was definitively diagnosed with asbestosis. He brought suit against Owens-Corning on April 6, 1984. Owens-Corning argued that the statute of limitations had started to run in March 1982 when the company doctor told Trieschock of his suspicions, not in April when Trieschock received the definitive diagnosis. The Court disagreed, holding that:

A plaintiff in a creeping disease case should not be required to have greater knowledge than his physicians about his medical condition. If those physicians are not reasonably certain about his diagnosis, then he certainly cannot be bound to have the knowledge necessary to start the statute of limitations running.

Id. at 866. While the initial conversation with the Owens-Corning doctor did not therefore start the statute running, the Court held that it "activated a duty on appellant's part to determine, with due diligence, whether he did, in fact, have that disease." Id.4

The defendants protest that Trieschock is no longer good law and point to language in Ackler v. Raymark Industries, Inc., 380 Pa.Super. 183,