For your delectation and delight, desultory dicta on the law of delicts.

Can an Expert Witness Be Too Biased to Be Allowed to Testify

May 20th, 2015

The Case of Barry Castleman

Barry Castleman has been a fixture in asbestos litigation for over three decades. By all appearances, he was the creation of the litigation industry. Castleman received a bachelor of science degree in chemical engineering in 1968, and a master’s degree in environmental engineering, in 1972. In 1975, he started as a research assistant to plaintiffs’ counsel in asbestos litigation, and in 1979, he commenced his testimonial adventures as a putative expert witness for plaintiffs’ counsel. Enrolled in a doctoral program, Castleman sent chapters of his thesis to litigation industry mentors for review and edits. In 1985, Castleman received a doctorate degree, with the assistance of a Ron Motley fellowship. See John M. Fitzpatrick, “Digging Deep to Attack Bias of Plaintiff Experts,” DRI Products Liability Seminar (2013).

Castleman candidly testified, on many occasions, that he was not an epidemiologist, a biostatistician, a toxicologist, a physician, a pathologist, or any other kind of healthcare professional. He is not a trained historian. Understandably, courts puzzled over exactly what someone like Castleman should be allowed to testify about. Many courts limited or excluded Castleman from remunerative testimonial roles[1]. Still, in the face of his remarkably inadequate training, education, and experience, Castleman persisted, and often prevailed, in making a living at testifying about the historical “state of the art” of medical knowledge about asbestos over time.

The result was often not pretty. Castleman worked not just as an expert witness, but also as an agent of plaintiffs’ counsel to suppress evidence. “The Selikoff – Castleman Conspiracy” (May 13, 2011). As a would-be historian, Castleman was controlled and directed by the litigation industry to avoid inconvenient evidence. “Discovery into the Origin of Historian Expert Witnesses’ Opinions” (Jan. 30, 2012). Despite his covert operations, and his exploitation of defendants’ internal documents, Castleman complained more than anyone about the scrutiny created by his self-chosen litigation roles. In 1985, pressed for materials he had considered in formulating his “opinions,” Castleman wrote a personal letter to the judge, the Hon. Hugh Gibson of Galveston, Texas, to object to lawful discovery into his activities:

“1. It threatens me ethically through demands that I    divulge material submitted in confidence, endangering my good name and reputation.
2. It exposes me to potential liability arising from the release of correspondence and other materials provided to me by others who assumed I would honor their confidence.
3. It jeopardizes my livelihood in that material requested reveals strategies of parties with whom I consult, as well as other materials of a confidential nature.
4. It is far beyond the scope of relevant material to my qualifications and the area of expert testimony offered.
5. It is unprecedented in 49 prior trials and depositions where I have testified, in federal and state courts all over the United States, including many cases in Texas. Never before have I had to produce such voluminous and sensitive material in order to be permitted to testify.
6. It is excessively and unjustifiably intrusive into my personal and business life.
7. I have referenced most of the information I have in my 593-page book, “Asbestos: Medical and Legal Aspects.” The great majority of the information I have on actual knowledge of specific defendants has come from the defendants themselves.
8. All information that I have which is relevant to my testimony and qualifications has been the subject of numerous trials and depositions since 1979.”

Castleman Letter to Hon. Hugh Gibson (Nov. 5, 1985).

Forty years later, Castleman is still working for the litigation industry, and courts are still struggling to figure out what role he should be allowed as a testifying expert witness.

Last year, the Delaware Supreme Court had to order a new trial for R. T. Vanderbilt, in part because Castleman had blurted out non-responsive, scurrilous hearsay statements that:

(1) employees of Johns-Manville (a competitor of R.T. Vanderbilt) had called employees of Vanderbilt “liars;”

(2) R.T. Vanderbilt spent a great amount of money on studies and activities to undermine federal regulatory action on talc; and

(3) R.T. Vanderbilt was “buying senators and lobbying the government.”

The Delaware court held that Castleman’s gratuitous, unsolicited testimony on cross-examination was inadmissible, and that his conduct required a new trial.  R.T. Vanderbilt Co. v. Galliher, No. 510, 2013, 2014 WL 3674180 (Del. July 24, 2014).

Late last year, a federal court ruled, pre-trial, that Castleman may testify over Rule 702 objections because he “possesses ‘specialized knowledge’ regarding the literature relating to asbestos available during the relevant time periods,” and that his testimony “could be useful to the jury as a ‘sort of anthology’ of the copious available literature.” Krik v. Crane Co., No. 10-cv-7435, – F. Supp. 2d -, 2014 WL 5350463, *3 (N.D. Ill. Oct. 21, 2014). Because Castleman was little more than a sounding board for citing and reading sections of the historical medical literature, the district court prohibited him from testifying as to the accuracy of any conclusions in the medical literature. Id.

Last week, another federal court took a different approach to keeping Castleman in business. In ruling on defendant’s Rule 702 objections to Castleman, the court held:

“I agree with defendant that plaintiffs have made no showing that Castleman is qualified to explain the meaning and significance of medical literature. Further, there is no suggestion in Krik that Castleman is qualified as an expert in that respect. To the extent that plaintiffs want Castleman simply to read excerpts from medical articles, they do not explain how doing so could be helpful to the jury. Accordingly, I am granting defendant’s motion as it relates to Castleman’s discussion of the medical literature.


However, Castleman’s report also includes discussions of articles in trade journals and government publications, which, presumably, would not require medical expertise to understand or summarize.”

Suoja v. Owens-Illinois, Inc., 2015 U.S. Dist. LEXIS 63170, at *3 (W.D.Wisc. May 14, 2015). Judge Barbara Crabb thus disallowed medical state of the art testimony from Castleman, but permitted him to resume his sounding board role for non-medical and other historical documents referenced in his Rule 26 report.

The strange persistence of Barry Castleman, and the inconsistent holdings of dozens of opinions strewn across the asbestos litigation landscape, raise the question whether someone so biased, so entrenched in a litigation role, so lacking in the requisite expertise, should simply be expunged from the judicial process. Rather than struggling to find some benign, acceptable role for Barry Castleman, perhaps courts should just say no. “How Testifying Historians Are Like Lawn-Mowing Dogs” (May 24, 2010).

[1] See, e.g., Van Harville v. Johns-Manville Sales Corp., CV-78-642-H (S.D. Ala 1979); In re Related Asbestos Cases, 543 F. Supp. 1142, 1149 (N.D. Cal. 1982) (rejecting Castleman’s bid to be called an “expert”) (holding that the court was “not persuaded that Mr. Castleman, as a layperson, possesses the expertise necessary to read complex, technical medical articles and discern which portions of the articles would best summarize the authors’ conclusions”); Kendrick v. Owens-Corning Fiberglas Corp., No. C-85-178-AAm (E.D. Wash. 1986); In re King County Asbestos Cases of Levinson, Friedman, Vhugen, Duggan, Bland and Horowitz, No. 81-2-08702-7, (Washington St. Super. Ct. for King Cty.1987); Franze v. Celotex Corp., C.A. No. 84-1316 (W.D. Pa.); Dunn v. Hess Oil Virgin Islands Corp., C.A. No. 1987-238 (D.V.I. May 16, 1989) (excluding testimony of Barry Castleman); Rutkowski v. Occidental Chem. Corp., No. 83 C 2339, 1989 WL 32030, at *1 (N.D. Ill. Feb. 16, 1989) (“Castleman lacks the medical background and experience to evaluate and analyze the articles in order to identify which parts of the articles best summarize the authors’ conclusions.”); In re Guam Asbestos Litigation, 61 F.3d 910, 1995 WL 411876 (9th Cir. 1995) (Kozinski, J., dissenting) (“I would also reverse because Barry Castleman was not qualified to testify as an expert witness on the subject of medical state of the art or anything else; he appears to have read a number of articles for the sole purpose of turning himself into an expert witness. Reductio ad absurdum.”); McClure v. Owens Corning Fiberglas Corp. 188 Ill. 2d 102, 720 N.E.2d 242 (1999) (rejecting probativeness of Castleman’s testimony about company conduct).

Professor Bernstein’s Critique of Regulatory Daubert

May 15th, 2015

In the law of expert witness gatekeeping, the distinction between scientific claims made in support of litigation positions and claims made in support of regulations is fundamental. In re Agent Orange Product Liab. Litig., 597 F. Supp. 740, 781 (E.D.N.Y. 1984) (“The distinction between avoidance of risk through regulation and compensation for injuries after the fact is a fundamental one”), aff’d 818 F.2d 145 (2d Cir. 1987), cert. denied sub nom. Pinkney v. Dow Chemical Co., 487 U.S. 1234 (1988). Although scientists proffer opinions in both litigation and regulatory proceedings, their opinions are usually evaluated by substantially different standards. In federal litigation, civil and criminal, expert witnesses must be qualified and have an epistemic basis for their opinions, to satisfy the statutory requirements of Federal Rule of Evidence 702, and they must have reasonably relied upon otherwise inadmissible evidence (such as the multiple layers of hearsay involved in an epidemiologic study) under Rule 703. In regulatory proceedings, scientists are not subject to admissibility requirements and the sufficiency requirements set by the Administrative Procedures Act are extremely low[1].

Some industry stakeholders are aggrieved by the low standards for scientific decision making in certain federal agencies, and they have urged that the more stringent litigation evidentiary rules be imported into regulatory proceedings. There are several potential problems with such reform proposals. First, the epistemic requirements of science generally, or of Rules 702 and 703 in particular, are not particularly stringent. Scientific method leads to plenty of false positive and false negative conclusions, which are subject to daily challenge and revision. Scientific inference is not necessarily so strict, as much as ordinary reasoning is so flawed, inexact, and careless. Second, the call for “regulatory Daubert” ignores mandates of some federal agency enabling statutes and guiding regulations, which call for precautionary judgments, and which allow agencies to decide issues on evidentiary display that fall short of epistemic warrants for claims of knowledge.

Many lawyers who represent industry stakeholders have pressed for extension of Daubert-type gatekeeping to federal agency decision making. The arguments for constraining agency action find support in the over-extended claims that agencies and so-called public interest science advocates make in support of agency measures. Advocates and agency personnel seem to believe that worst-case scenarios and overstated safety claims are required as “bargaining” positions to achieve the most restrictive and possibly the most protective regulation that can be gotten from the administrative procedure, while trumping industry’s concerns about costs and feasibility. Still, extending Daubert to regulatory proceedings could have the untoward result of lowering the epistemic bar for both regulators and litigation fact finders.

In a recent article, Professor David Bernstein questions the expansion of Daubert into some regulatory realms. David E. Bernstein, “What to Do About Federal Agency Science: Some Doubts About Regulatory Daubert,” 22 Geo. Mason L. Rev. 549 (2015)[cited as Bernstein]. His arguments are an important counterweight to those who insist on changing agency rulemaking and actions at every turn. As an acolyte and a defender of scientific scruples and reasoning in the courts, Bernstein’s arguments are worth taking seriously.

Bernstein reminds us that bad policy, as seen in regulatory agency rulemaking or decisions, is not always a scientific issue. In any event, regulatory actions, unlike jury decisions, are not, or at least should not be, “black boxes.” The agency’s rationale and reasoning are publicly stated, subject to criticism, and open to revision. Jury decisions are opaque, non-transparent, potentially unreasoned, not carefully articulated, and not subject to revision absent remarkable failures of proof.

One line of argument[2] pursued by Professor Bernstein follows from his observation that Daubert procedures are required to curtail litigation expert witness “adversarial bias.” Id. at 555. Bernstein traces adversarial bias to three sources:

(1) conscious bias;

(2) unconscious bias; and

(3) selection bias.

Id. Conscious bias stems from deliberate attempts by “hired guns” to deliver opinions that satisfy the lawyers who retained them. The problem of conscious bias is presented by “hired guns” who will adapt their opinions to the needs of the attorney who hires them. Unconscious biases are the more subtle, but no less potent determinants of expert witness behavior, which are created by financial dependence upon, and allegiance to, the witness’s paymaster. Selection bias results from lawyers’ ability to choose expert witnesses to support their claims, regardless whether those witnesses’ opinions are representative of the scientific community. Id.

Professor Bernstein’s taxonomy of bias is important, but incomplete. First, the biases he identifies operate fulsomely in regulatory settings. Although direct financial remuneration is usually not a significant motivation for a scientist to testify before an agency, or to submit a whitepaper, professional advancement and cause advocacy are often powerful incentives at work. These incentives for self-styled public interest zealots may well create more powerful distortions of scientific judgment than any monetary factors in private litigation settings. As for selection bias, lawyers are ethically responsible for screening their expert witnesses, and there can be little doubt that once expert witnesses are disclosed, their opinions will align with their sponsoring parties’ interests. This systematic bias, however, does not necessarily mean that both side’s expert witnesses will necessarily be unrepresentative or unscientific. In the silicone gel breast implant litigation (MDL 926), Judge Pointer, the presiding judge, insisted that both sides’ witnesses were “too extreme,” and he was stunned when his court-appointed expert witnesses filed reports that vindicated the defendants’ expert witnesses’ positions[3]. The defendants had selected expert witnesses who analyzed the data on sound scientific principles; the plaintiffs had selected expert witnesses who overreached in their interpretation of the evidence. Furthermore, many scientific disputes, which find their way into the courtroom, will not have the public profile of silicone gel breast implants, and for which there may be no body of scientific community opinion from which lawyers could select “outliers,” even if they wished to do so.

Professor Bernstein’s offered taxonomy of bias is incomplete because it does not include the most important biases that jurors (and many judges) struggle to evaluate:

random errors;

systematic biases;

confounding; and

cognitive biases.

These errors and biases, along with their consequential fallacies of reasoning, apply with equal force to agency and litigation science. Bernstein does point out, however, an important institutional difference between jury or judge trials and agency review and decisions based upon scientific evidence: agencies often have extensive in-house expertise. Although agency expertise may sometimes be blinded by its policy agenda, agency procedures usually afford the public and the scientific community to understand what the agency decided, and why, and to respond critically when necessary. In the case of the Food and Drug Administration, agency decisions, whether pro- or contra-industry positions are dissected and critiqued by the scientific and statistical community with great care and relish. Nothing of the same sort is possible in response to a jury verdict.

Professor Bernstein is not a science nihilist, and he would not have reviewing courts give a pass to whatever nonsense federal agencies espouse. He calls for enforcement of available statutory requirements that agency action be based upon the “best available science,” and for requiring agencies to explicitly separate and state their policy and scientific judgments. Bernstein also urges greater use of agency peer review, such as occasionally seen from the Institute of Medicine (soon to be the National Academy of Medicine), and the use of Daubert-like criteria for testimony at agency hearings. Bernstein at 554.

Proponents of regulatory Daubert should take Professor Bernstein’s essay to heart, with a daily dose of atorvastatin. Importing Rule 702 into agency proceedings may well undermine the rule’s import in litigation, civil and criminal, while achieving little in the regulatory arena. Consider the pending OSHA rulemaking for lowering the permissible exposure limit (PEL) of crystalline silica in the workplace. OSHA, and along with some public health organizations, has tried to justify this rulemaking on the basis of many overwrought claims of the hazards of crystalline silica exposure at current levels. Clearly, there are some workers who continue to work in unacceptably hazardous conditions, but the harms sustained by these workers can be tied to violations of the current PEL; they are hardly an argument for lowering that current PEL. Contrary to the OSHA’s parade of horribles, silicosis mortality in the United States has steadily declined over the last several decades. The following chart draws upon NIOSH and other federal governmental data:


Silicosis Deaths by Year


Silicosis deaths, crude and age-adjusted death rates, for U.S. residents age 15 and over, 1968–2007

from Susan E. Dudley & Andrew P. Morriss, “Will the Occupational Safety and Health Administration’s Proposed Standards for Occupational Exposure to Respirable Crystalline Silica Reduce Workplace Risk?” 35 Risk Analysis (2015), in press, doi: 10.1111/risa.12341 (NIOSH reference number: 2012F03–01, based upon multiple cause-of-death data from National Center for Health Statistics, National Vital Statistics System, with population estimates from U.S. Census Bureau).

The decline in silicosis mortality is all the more remarkable because it occurred in the presence of stimulated reporting from silicosis litigation, and misclassification of coal workers’ pneumoconiosis in coal-mining states.

The decline in silicosis mortality may be helpfully compared with the steady rise in mortality from accidental falls among men and women 65 years old, or older:

CDC MMWR Death Rates from Unintentional Falls 2015

Yahtyng Sheu, Li-Hui Chen, and Holly Hedegaard, “QuickStats: Death Rates* from Unintentional Falls† Among Adults Aged ≥ 65 Years, by Sex — United States, 2000–2013,” 64 CDC MMWR 450 (May 1, 2015). Over the observation period, these death rates roughly doubled in both men and women.

Is there a problem with OSHA rulemaking? Of course. The agency has gone off on a regulatory frolic and detour trying to justify an onerous new PEL, without any commitment to enforcing its current silica PEL. OSHA has invoked the prospect of medical risks, many of which are unproven, speculative, and remote, such as lung cancer, autoimmune disease, and kidney disease. The agency, however, is awash with PhDs, and I fear that Professor Bernstein is correct that the distortions of the science are not likely to be corrected by applying Rule 702 to agency factfinding. Courts, faced with the complex prediction models, with disputed medical claims made by agency and industry scientists, will do what they usually do, shrug and defer. And the blow back of the “judicially approved” agency science in litigation contexts will be a cure worse than the disease. At bottom, the agency twisting of science is driven by policy goals and considerations, which require public debate and scrutiny, sound executive judgment, with careful legislative oversight and guidance.

[1] Even under the very low evidentiary and procedural hurdles, federal agencies still manage to outrun their headlights on occasion. See, e.g., Industrial Union Department v. American Petroleum Institute, 448 U.S. 607 (1980) (The Benzene Case); Gulf South Insulation v. U.S. Consumer Product Safety Comm’n, 701 F.2d 1137 (5th Cir. 1983); Corrosion Proof Fittings v. EPA, 947 F2d 1201 (5th Cir 1991).

[2] See also David E. Bernstein, “The Misbegotten Judicial Resistance to the Daubert Revolution,” 89 Notre Dame L. Rev. 27, 31 (2013); David E. Bernstein, “Expert Witnesses, Adversarial Bias, and the (Partial) Failure of the Daubert Revolution,” 93 Iowa L. Rev. 451, 456–57 (2008).

[3] Judge Pointer was less than enthusiastic about performing any gatekeeping role. Unlike most of today’s MDL judges, he was content to allow trial judges in the transferor districts to decide Rule 702 and other pre-trial issues. See Note, “District Judge Takes Issue With Circuit Courts’ Application of Gatekeeping Role” 3 Federal Discovery News (Aug. 1997) (noting that Chief Judge Pointer had criticized appellate courts for requiring district judges to serve as gatekeepers of expert witness testimony).

Sophisticated Intermediary Defense Prevails in New York

May 9th, 2015

Several years ago, the New York Appellate Division, 4th Department, reversed summary judgment for defendants in the cases of two workers who alleged that they had developed silicosis from silica exposure to defendants’ silica, at the Olean, New York, facility of their employer, Dexter Corporation (now Henkel Corporation). The trial court motions were based upon the “sophisticated intermediary” defense, but the Appellate Division reversed, holding that there was a genuine issue of material fact with respect to potential confusion between amorphous and crystalline silica, based upon statements in an affidavit of a plaintiffs’ expert witness, made without personal knowledge. See Pete Brush, “NY Court Revives Workers’ Silica Inhalation Suits” (March 24, 2009).

On remand, further discovery and an amplified evidentiary record led to new motions for summary judgment. In a February 26, 2015, order, the New York Supreme Court for Cattaraugus County granted the motions, noting that “the sophisticated intermediary doctrine was tailor-made” for the facts of the two cases. Rickicki v. Borden Chemical, et al., Index No. 53395, and Crowley v. C-E Minerals, Inc., et al., Index No. 61024, N.Y. Supreme Ct., Cattaraugus Cty. (Feb. 26, 2015) (Patrick H. NeMoyer, J.), Slip op. at 24. See also Casetext, “Summary Judgment Re-entered After Remand from the NY Appellate Division in Rickick v. Borden” (April 2, 2015); HarrisMartin, “N.Y. Trial Court Awards Summary Judgment to Silica Defendant, Recognizes Sophisticated Intermediary Doctrine” (March 27, 2015).

The Rickicki case turned 25 years old in February 2015.

Science as Adversarial Process versus Group Think

May 7th, 2015

Climate scientists, at least those scientists who believe that climate change is both real and an existential threat to human civilization, have invoked their consensus as an evidentiary ground for political action. These same scientists have also used their claim of a consensus to shame opposing points of view (climate change skeptics) as coming from “climate change deniers.”

Consensus, or “general acceptance” as it is sometimes cast in legal discussions, is rarely more than nose counting. At best, consensus is a proxy for data quality and inferential validity. At worst, consensus is a manifestation of group think and herd mentality. Debates about climate change, as well as most scientific issues, would progress more dependably if there were more data, and less harrumphing about consensus.

Olah’s Nobel Speech

One Nobel laureate, Professor George Olah, explicitly rejected the kumbaya view of science and its misplaced emphasis on consensus and collaboration. In accepting his Nobel Prize in Chemistry, Olah emphasized the value of adversarial challenges in refining and establishing scientific discovery:

“Intensive, critical studies of a controversial topic always help to eliminate the possibility of any errors. One of my favorite quotation is that by George von Bekessy (Nobel Prize in Medicine, 1961).

‘[One] way of dealing with errors is to have friends who are willing to spend the time necessary to carry out a critical examination of the experimental design beforehand and the results after the experiments have been completed. An even better way is to have an enemy. An enemy is willing to devote a vast amount of time and brain power to ferreting out errors both large and small, and this without any compensation. The trouble is that really capable enemies are scarce; most of them are only ordinary. Another trouble with enemies is that they sometimes develop into friends and lose a good deal of their zeal. It was in this way the writer lost his three best enemies. Everyone, not just scientists, needs a few good enemies!’”

George A. Olah, “My Search for Carbocations and Their Role in Chemistry,” Nobel Lecture (Dec. 8, 1994), quoting George von Békésy, Experiments in Hearing 8 (N.Y. 1960); see also McMillan v. Togus Reg’l Office, Dep’t of Veterans Affairs, 294 F. Supp. 2d 305, 317 (E.D.N.Y. 2003) (“As in political controversy, ‘science is, above all, an adversary process.’”) (internal citation omitted).

Carl Sagan expressed similar views about the importance of skepticism in science :

“At the heart of science is an essential balance between two seemingly contradictory attitudes — an openness to new ideas, no matter how bizarre or counterintuitive they may be, and the most ruthless skeptical scrutiny of all ideas, old and new. This is how deep truths are winnowed from deep nonsense.”

Carl Sagan, The Demon-Haunted World: Science as a Candle in the Dark (1995); See also Cary Coglianese, “The Limits of Consensus,” 41 Environment 28 (April 1999).

Michael Crichton, no fan of Sagan, agreed at least on the principle:

“I want to . . . talk about this notion of consensus, and the rise of what has been called consensus science. I regard consensus science as an extremely pernicious development that ought to be stopped cold in its tracks. Historically, the claim of consensus has been the first refuge of scoundrels; it is a way to avoid debate by claiming that the matter is already settled. Whenever you hear the consensus of scientists agrees on something or other, reach for your wallet, because you’re being had.

Let’s be clear: the work of science has nothing whatever to do with consensus. Consensus is the business of politics. Science, on the contrary, requires only one investigator who happens to be right, which means that he or she has results that are verifiable by reference to the real world. In science consensus is irrelevant. What is relevant is [sic] reproducible results. The greatest scientists in history are great precisely because they broke with the consensus.  There is no such thing as consensus science. If it’s consensus, it isn’t science. If it’s science, it isn’t consensus. Period.34

Michael Crichton, “Lecture at California Institute of Technology: Aliens Cause Global Warming” (Jan. 17, 2003) (describing many examples of how “consensus” science historically has frustrated scientific progress).

Crystalline Silica, Carcinogenesis, and Faux Consensus

Clearly, there are times when consensus in science works against knowledge and data-driven inferences. Consider the saga of crystalline silica and lung cancer. Suggestions that silica causes lung cancer date back to the 1930s, but the suggestions were dispelled by data. The available data were evaluated by the likes of Wilhelm Heuper[1], Cuyler Hammond[2] (Selikoff’s go-to-epidemiologist), Gerrit Schepers[3], and Hans Weill[4]. Even etiologic fabulists, such as Kaye Kilburn, disclaimed any connection between silica or silicosis and lung cancer[5]. As recently as 1988, august international committees, writing for the National Institute of Occupational Safety and Health, acknowledged the evidentiary insufficiency of any claim that silica caused lung cancer[6].

IARC (1987)

So what happened to the “consensus”? A group of activist scientists, who disagreed with the consensus, sought to establish their own, new consensus. Working through the International Agency for Research on Cancer (IARC), these scientists were able to inject themselves into the IARC working group process, and gradually raise the IARC ranking of crystalline silica. In 1987, the advocate scientists were able to move the IARC to adopt a “limited evidence” classification for crystalline silica.

The term “limited evidence” is defined incoherently by the IARC as evidence that provides for a “credible” causal explanation, even though chance, bias, and confounding have not been adequately excluded. Despite the incoherent definition that giveth and taketh away, the 1987 IARC reclassification[7] into Group 2A had regulatory consequences that saw silica classified as a “regulatory carcinogen,” or a substance that was “reasonably anticipated to be a carcinogen.”

The advocates’ prophecy was self-fulfilling. In 1996, another working group of the IARC met in Lyon, France, to deliberate on the classification of crystalline silica. The 1996 working group agreed, by a close vote, to reclassify crystalline silica as a “known human carcinogen,” or a Group 1 carcinogen. The decision was accepted and reported officially in volume 68 of the IARC monographs, in 1997.

According to participants, the debate was intense and the vote close. Here is the description from one of the combatants;

“When the IARC Working Group met in Lyon in October 1996 to assess the carcinogenicity of crystalline silica, a seemingly interminable debate ensued, only curtailed by a reminder from the Secretariat that the IARC was concerned with the identification of carcinogenic hazards and not the evaluation of risks. The important distinction between the potential to cause disease in certain circumstances, and in what circumstances, is not always appreciated.

*   *   *   *   *

Even so, the debate in Lyon continued for some time, finally ending in a narrow vote, reflecting the majority view of the experts present at that particular time.”

See Corbett McDonald, “Silica and Lung Cancer: Hazard or Risk,” 44 Ann. Occup. Hyg. 1, 1 (2000); see also Corbett McDonald & Nicola Cherry, “Crystalline Silica and Lung Cancer: The Problem of Conflicting Evidence,” 8 Indoor Built Env’t 8 (1999).

Although the IARC reclassification hardly put the silica lung cancer debate to rest, it did push the regulatory agencies to walk in lockstep with the IARC and declare crystalline silica to be a “known human carcinogen.” More important, it gave regulators and scientists an excuse to avoid the hard business of evaluating complicated data, and of thinking for themselves.


From a sociology of science perspective, the aftermath of the 1997 IARC monograph is a fascinating natural experiment to view the creation of a sudden, thinly supported, new orthodoxy. To be sure, there were scientists who looked carefully at the IARC’s stated bases and found them inadequate, inconsistent, and incoherent[8]. One well-regarded pulmonary text in particular gives the IARC and regulatory agencies little deference:

“Silica-induced lung cancer

A series of studies suggesting that there might be a link between silica inhalation and lung cancer was reviewed by the International Agency for Research on Cancer in 1987, leading to the conclusion that the evidence for carcinogenicity of crystalline silica in experimental animals was sufficient, while in humans it was limited.112 Subsequent epidemiological publications were reviewed in 1996, when it was concluded that the epidemiological evidence linking exposure to silica to the risk of lung cancer had become somewhat stronger.113 but that in the absence of lung fibrosis remained scanty.113 The pathological evidence in humans is also weak in that premalignant changes around silicotic nodules are seldom evident.114 Nevertheless, on this rather insubstantial evidence, lung cancer in the presence of silicosis (but not coal or mixed-dust pneumoconiosis) has been accepted as a pre­scribed industrial disease in the UK since 1992.115 Some subsequent studies have provided support for this decision.116 In contrast to the sparse data on classic silicosis, the evidence linking carcinoma of the lung to the rare diffuse pattern of fibrosis attributed to silica and mixed dusts is much stronger and appears incontrovertible.33,92

Bryan Corrin[9] & Andrew Nicholson, Pathology of the Lungs (3d ed. 2011).


Cognitive biases cause some people to see a glass half full, while others see it half empty. Add a “scientific consensus” to the mix, and many people will see a glass filled 5% as 95% full.

Consider a paper by Centers for Disease Control and NIOSH authors on silica exposure and morality from various diseases. Geoffrey M. Calvert, Faye L. Rice, James M. Boiano, J. W. Sheehy, and Wayne T. Sanderson, “Occupational silica exposure and risk of various diseases: an analysis using death certificates from 27 states of the United States,” 60 Occup. Envt’l Med. 122 (2003). The paper was nominated for the Charles Shepard Award for Best Scientific Publication by a CDC employee, and was published in the British Medical Journal’s publication on occupational medicine. The study analyzed death certificate data from the U.S. National Occupational Mortality Surveillance (NOMS) system, which is based upon the collaboration of NIOSH, the National Center for Health Statistics, the National Cancer Institute, and some state health departments. Id. at 122.

From about 4.8 million death certificates included in their analysis, the authors found a statistically decreased mortality odds ratio (MOR) for lung cancer among those who had silicosis (MOR = 0.70, 95% C.I., 0.55 to 0.89). Of course, with silicosis on the death certificates along with lung cancer, the investigators could be reasonably certain about silica exposure. Given the group-think in occupational medicine about silica and lung cancer, the authors struggled to explain away their finding:

“Although many studies observed that silicotics have an increased risk for lung cancer, a few studies, including ours, found evidence suggesting the lack of such an association. Although this lack of consistency across studies may be related to differences in study design, it suggests that silicosis is not necessary for an increased risk of lung cancer among silica exposed workers.”

Well this statement is at best disingenuous. The authors did not merely find a lack of an association; they found a statistically significance inverse or “negative” association between silicosis and lung cancer. So it is not the case that silicosis is not necessary for an increased risk; silicosis is antithetical to an increased risk.

Looking at only death certificate information, without any data on known or suspected confounders (“diet, hobbies, tobacco use, alcohol use, or medication,” id. at 126, or comorbid diseases or pulmonary impairment, or other occupational or environmental exposures), the authors inferred low, medium, high, and “super high” silica exposure from job categories. Comparing the ever-exposed categories with low exposure yielded absolutely no association between exposure and lung cancer, and subgroup analyses (without any correction for multiple comparisons) found little association, although two subgroups were nominally statistically significantly increased, and one was nominally statistically significantly decreased, at very small deviations from expected:

Lung Cancer Mortality Odds Ratios (p-value for trend < 0.001)

ever vs. low/no exposure:                0.99 (0.98 to 1.00)

medium vs. low/no exposure:         0.88 (0.87 to 0.90)

high vs. low/no exposure:                 1.13 (1.11 to 1.15)

super high vs. low/no exposure:      1.13 (1.06 to 1.21)

Id. at Table 4, and 124.

On this weak evidentiary display, the authors declare that their “study corroborates the association between crystalline silica exposure and silicosis, lung cancer.” Id. at 123. In their conclusions, they elaborate:

“Our findings support an association between high level crystalline silica exposure and lung cancer. The statistically significant MORs for high and super high exposures compared with low/no exposure (MORs = 1.13) are consistent with the relative risk of 1.3 reported in a meta-analysis of 16 cohort and case-control studies of lung cancer in crystalline silica exposed workers without silicosis”

Id. at 126. Actually not; Calvert’s reported MORs exclude an OR of 1.3.

The Calvert study thus is a stunning example of authors, prominent in the field of public health, looking at largely exculpatory data and declaring that they have confirmed an important finding of silica carcinogenesis. And to think that United States taxpayers paid for this paper, and that the authors almost received an honorific award for this thing!

[1] Wilhelm Hueper, “Environmental Lung Cancer,” 20 Industrial Medicine & Surgery 49, 55-56 (1951) (“However, the great majority of investigators have come to the conclusion that there does not exist any causal relation between silicosis and pulmonary or laryngeal malignancy”).

[2] Cuyler Hammond & W. Machle, “Environmental and Occupational Factors in the Development of Lung Cancer,” Ch. 3, pp. 41, 50, in E. Mayer & H. Maier, Pulmonary Carcinoma: Pathogenesis, Diagnosis, and Treatment (N.Y. 1956) (“Studies by Vorwald (41) and others agree in the conclusion that pneumoconiosis in general, and silicosis in particular, do not involve any predisposition of lung cancer.”).

[3] Gerrit Schepers, “Occupational Chest Diseases,” Chap. 33, in A. Fleming, et al., eds., Modern Occupational Medicine at 455 (Philadelphia 2d ed. 1960) (“Lung cancer, of course, occurs in silicotics and is on the increase. Thus far, however, statistical studies have failed to reveal a relatively enhanced incidence of pulmonary neoplasia in silicotic subjects.”).

[4] Ziskind, Jones, and Weill, “State of the Art: Silicosis” 113 Am. Rev. Respir. Dis. 643, 653 (1976) (“There is no indication that silicosis is associated with increased risk for the development of cancer of the respiratory or other systems.”); Weill, Jones, and Parkes, “Silicosis and Related Diseases, Chap. 12, in Occupational Lung Disorders (3d ed. 1994) (“It may be reasonably concluded that the evidence to date that occupational exposure to silica results in excess lung cancer risk is not yet persuasive.”).

[5] Kaye Kilburn, Ruth Lilis, Edwin Holstein, “Silicosis,” in Maxcy-Rosenau, Public Health and Preventive Medicine, 11th ed., at 606 (N.Y. 1980) (“Lung cancer is apparently not a complication of silicosis”).

[6] NIOSH Silicosis and Silicate Disease Committee, “Diseases Associated With Exposure to Silica and Nonfibrous Silicate Minerals,” 112 Arch. Path. & Lab. Med. 673, 711b, ¶ 2 (1988) (“The epidemiological evidence at present is insufficient to permit conclusions regarding the role of silica in the pathogenesis of bronchogenic carcinoma.”)

[7] 42 IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans at 22, 111, § 4.4 (1987).

[8] See, e.g., Patrick A. Hessel, John F. Gamble, J. Bernard L. Gee, Graham Gibbs, Francis H. Y. Green, W. Keith C. Morgan, and Brooke T. Mossman, “Silica, Silicosis, and Lung Cancer: A Response to A Recent Working Group,” 42 J. Occup. Envt’l Med. 704, 718 (2000) (“The data demonstrate a lack of association between lung cancer and exposure to crystalline silica in human studies. Furthermore, silica is not directly genotoxic and has been to be a pulmonary carcinogen in only one animal species, the rat, which seems to be an inappropriate carcinogenesis in humans.”)

[9] Professor of Thoracic Pathology, National Heart and Lung Institute, Imperial College School of Medicine; Honorary Consultant Pathologist, Brompton Hospital, London, UK.

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