TORTINI

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

Ramazzini Serves Courtroom Silica Science Al Dente

July 25th, 2015

Collegium Ramazzini styles itself as an “independent, international academy.” The Collegium Ramazzini was founded in 1982, by the late Irving Selikoff and others to serve as an advocacy forum for their pro-compensation and aggressive regulation views on social and political issues involving occupational and environmental health.

The Collegium is a friendly place where plaintiffs’ expert witnesses, consultants, and advocates never have to declare their conflicts of interest.[1] Last year, in October 2014, the Collegium conducted a conference on silica health issues, entitled “Silica Three Hundred Years Later: Occupational Exposure, Medical Monitoring, and Regulation.”

The silica session was chaired by Christine Oliver, one of plaintiff’s key expert witnesses in Allen v. Martin Surfacing, 263 F.R.D. 47 (D. Mass. 2009). SeeBad Gatekeeping or Missed Opportunity – Allen v. Martin Surfacing” (Nov. 30, 2012). The purported goal of the session was

“to shine a light on silica as a persistent and dangerous threat to the health of exposed workers worldwide,” focusing on the following issues:

“1) Occupational silica exposures, new and old;

2) silica as a recognized human lung carcinogen and its interaction with other lung carcinogens such as tobacco smoke;

3) the role of silica and silicosis in tuberculosis;

4) issues relevant to medical surveillance of silica-exposed workers as set forth in OSHA’s proposed silica standard;

5) the role of the US Government in protecting the health of silica-exposed workers; and

6) international variability in addressing the threat to worker health posed by silicosis.”

Recently, the Collegium updated its website to provide PDF files of some of the conference presentations:

Carol H. Rice, “Silica – old, new and emerging uses result in worker exposure

Arthur L. Frank, “Silica as a lung carcinogen

Rodney Ehrlich, “Silica in the head of the snake. Silica, gold mining, and tuberculosis in southern Africa

Christine Oliver, “Medical surveillance for silica-related disease: the Collegium responds to OSHA’s proposed rulemaking,”

Gregory R. Wagner, “US Government role in recognizing, reducing, and regulating silica risk: 80 years and counting

Sverre Langard, “Silicosis 300 years after Ramazzini: Eradication in some countries, increased incidence in others

A poster session chaired by Melissa McDiarmid and Carol Rice, revealingly titled “Sustainable Work 2020 – an advocacy platform for Horizon 2020,” followed. Casey Bartrem asked whether “Asbestos-induced lung cancer in Germany: is the compensation practice in accordance with the epidemiological findings?” Odds are that this presentation was a brief for greater compensation. Xaver Baur of Germany, presented on the “Ethics in the applied sciences: The challenge of preventing corporate influence over public health regulation,” but remarkably no one presented on the challenge of preventing the litigation and compensation industry’s influence over public health regulation.

You won’t find any cutting-edge science in the linked slides, but you will find some interesting revelations. Sverre Langard’s presentation makes the dramatic point that silicosis has been declining, despite the hand waving of OSHA Administrator David Michaels, and the histortions of Rosner and Markowitz. Consider Langard’s slide, based upon CDC data:

CDC Siicosis vs Asbestosis Mortality Over Time

And consider the admissions of Arthur Frank, veteran plaintiffs’ expert witness, who acknowledged that:

“until very recently it [silica] was not recognized as a carcinogen.”

True to form, Dr. Frank blamed Selikoff and his other teachers at Mt. Sinai Hospital in New York City, where he trained:

“At Mount Sinai I did not get trained that silica was a carcinogen”

Well, even a scurry of blind squirrels sometimes find their nuts!


[1][1] Some of the names on the list of Fellows and Emeritus Fellows reads like a “Who’s Who” of testifying expert witnesses, consultants, and advocates for the litigation industry:

Henry A. Anderson, Barry Castleman, David C. Christiani, Carl F. Cranor, Devra Lee Davis , John M. Dement, Arthur Frank, Bernard D. Goldstein, Howard Frumkin, Lennart Hardell, Peter F. Infante, Joseph LaDou, Philip Landrigan, Richard A. Lemen, Barry S. Levy, Roberto G. Lucchini, Steven B. Markowitz, Myron A. Mehlman, Ronald L. Melnick, Donna Mergler, Albert Miller, Franklin E. Mirer, Herbert L. Needleman, L. Christine Oliver, David M. Ozonoff, Carol H. Rice, Kenneth D. Rosenman, Sheldon W. Samuels, Ellen K. Silbergeld, Peter D. Sly, Martyn Thomas Smith, Colin L. Soskolne, Leslie Thomas Stayner, Daniel T. Teitelbaum, Laura Welch

The Unreasonable Success of Asbestos Litigation

July 25th, 2015

In asbestos litigation, the plaintiffs’ bar has apparently invented a perpetual motion machine that feeds on outrage that will never run out. Still, lawyers who have not filled their wallets with legal fees from asbestos cases sometimes attempt to replicate the machine. For the most part, the imitators have failed.

What accounts for the unreasonable success of asbestos litigation? Unlike pharmaceutical litigation, exposure does not require a prescription. Although asbestos insulators and applicators experienced the most exposure, other trades and occupations worked with, or near, asbestos materials. Anecdotal testimony of exposure suffices in almost every case. Add para-occupational exposure, and the sky’s the limit for the class of potential plaintiffs. See Lester Brickman, “Fraud and Abuse in Mesothelioma Litigation,” 88 Tulane L. Rev. 1071 (2014); Peggy Ableman, “The Garlock Decision Should be Required Reading for All Trial Court Judges in Asbestos Cases,” 37 Am. J. Trial Advocacy 479, 488 (2014).

Then there is the range of diseases and disorders attributable to asbestos. Excessive exposure to asbestos minerals cause non-malignant pleural plaques and thickening, as well as lung fibrosis, asbestosis. Some asbestos minerals cause mesothelioma, and despite a differential in potency among some of the minerals (between amosite and crocidolite), the general and specific causation of mesothelioma is often uncontested. Furthermore, lung cancer in the presence of asbestosis may be the result of interaction of asbestos exposure and cigarette smoking. Plaintiffs’ counsel and The Lobby have expanded the list of attributable diseases to include non-pulmonary cancers, only to find some defendants willing to pay money on these claims as well.

In addition to the ease of claiming, or manufacturing, exposure, and the willing cooperation of the occupational medical community in supporting medical causation, asbestos litigation is a lightning rod for moral outrage in the courtroom. Plaintiffs claim that “industry” knew about the hazards of asbestos, including its carcinogenicity, long before warnings appeared. Defending the knowledge claim requires nuanced explanation of shifting standards for establishing causality as epidemiology developed and was applied to putative asbestos-related cancer outcomes, as well as changing views about the latencies of asbestos-related diseases.

Every once in a while, plaintiffs’ and defense counsel[1], the media[2], the academy[3], and the insurance industry[4] ask whether “silica” is the next asbestos. Although the prospects have been, and remain, dim, plaintiffs’ counsel continue to try to build their litigation palace on sand, with predictably poor results. See Kimberley A. Strassel, “He Fought the Tort Bar — and Won,” Wall St. J. (May 4, 2009).

There are many serious disanalogies between asbestos and silica litigation. One glaring difference is the inability to summon any outrage over suppressed or nondisclosed knowledge of alleged silica cancer hazards. The silica cancer state of the art, written by those who are lionized in the asbestos litigation – Hueper, Schepers, and Hardy, along with NIOSH and the Surgeon General, all appropriately denied or doubted silica as a cause of lung cancer. See below. When the IARC shifted its views in the 1990s, under the weight of determined advocacy from some partisans in the occupational medicine community, and with the help from some rather biased reviews, industry promptly warned regardless of the lack of scientific support for the IARC’s conclusion. The manufacturing of faux consensus and certainty on silica and lung cancer is an important counter to the incessant media stories about the manufacturing of doubt on topics such as climate change.


[1] Robert D. Chesler, James Stewart, and Geoffrey T. Gibson, “Is Silica the Next Asbestos?” 176 N.J.L.J. 1 (June 28, 2004); Mark S. Raffman, “Where Will Silica Litigation Go?” 1 LJN Silica Legal News 1 (2005); Chris Michael Temple, “A Case for Why Silica Litigation Is Not the ‘Next Asbestos’,” LJN Product Liability Law & Strategy (2004).

[2] Jonathan D. Glater, “Suits on Silica Being Compared To Asbestos Cases,” N.Y. Times (Sept. 6, 2003).

[3] Michelle J. White, “Mass Tort Litigation: Asbestos,” in Jürgen Georg Backhaus, ed., Encyclopedia of Law and Economics 1 (2014); Melissa Shapiro, “Is Silica the Next Asbestos? An Analysis of the Silica Litigation and the Sudden Resurgence of Silica Lawsuit Filings,” 32 Pepperdine L. Rev. 4 (2005).

[4]Is silica the new asbestos?The Actuary (2005).


Historical Statements – – State-of-the-Art

Maxcy, ed., Rosenau Preventive Medicine and Hygiene 1051 (N.Y., 7th ed. 1951) (“Thus, there is no evidence that lung cancer is related in any way to silicosis.”)

May Mayers, “Industrial Cancer of the Lungs,” 4 Compensation Medicine 11, 12 (1952) (“Nevertheless, silicosis is not, apparently associated with, or productive of, lung cancer, whereas asbestosis very probably is.”) (Chief, Medical Unit, Division of Industrial Hygiene and Safety Standards, N.Y. Dep’t of Labor)

Geritt Schepers, “Occupational Chest Diseases,” Chap. 33, p. 455, ¶3, in A. Fleming, et al., eds., Modern Occupational Medicine (Phila. 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.”)

Spencer, Pathology of the Lung (1962) (“Silicosis and lung cancer inhaled silica, unlike asbestos, does not predispose to the development of lung cancer.”)

Wilhelm Hueper, Occupational and Environmental Cancers of the Respiratory System at 2-6 (N.Y. 1966) (“The bulk of the available epidemiologic evidence on the association of silicosis and lung cancer supports the view of a mere coincidental role of silicosis in this combination. *** From the evidence on hand, it appears that a well advanced silicosis does not seem to furnish a favorable soil for the development of cancer of the lung.”) (chief of the National Cancer Institute)

Harriet L. Hardy, “Current Concepts of Occupational Lung Disease of Interest to the Radiologist,” 2 Sem. Roentgenology 225, 231-32 (1967) (“cancer of the lung is not a risk for the silicotic. It is a serious risk following asbestos exposure and for hematite, feldspar, and uranium miners. This means that certain dusts and ionizing radiation alone or perhaps with cigarette smoke act as carcinogens.”)

Raymond Parkes, Occupational Lung Disorders 192 (London 1974) (“Bronchial carcinoma occasionally occurs in silicotic lungs but there is no evidence of a causal relationship between it and silicosis; indeed the incidence of lung cancer in miners with silicosis is significantly lower than in non-silicotic males.”)

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.”)

Robert Jones, “Silicosis,” Chap. 16, in W. Rom, et al., eds., Environmental and Occupational Medicine 205 (Boston 1983) (“The weight of epidemiologic evidence is against the proposition that silicosis carries an increased risk of respiratory malignancy.”)

W. Keith C. Morgan & Anthony Seaton, eds., Occupational Lung Diseases 266 (1984) (“It is generally believed that silicosis does not predispose to lung cancer. * * * On balance, it seems unlikely that silicosis itself predisposes to lung cancer.”)

1 Anderson’s Pathology at 910b (1985) (“There is no evidence that silica increases the risk of lung cancer, nor does it enhance tobacco induced carcinogenesis.”)

U.S. Dep’t of Health and Human Services, The Health Consequences of Smoking – Cancer and Chronic Lung Disease in the Workplace: A Report of the Surgeon General at 348, Chapter 8 “Silica‑Exposed Workers” (1985) (“the evidence does not currently establish whether silica exposure increases the risk of developing lung cancer in men.”)

J. Cotes & J. Steel, Work-Related Lung Disorders 156 (Oxford 1987) (“The inhalation of silica dust does not contribute to malignancy.”)

NIOSH Silicosis and Silicate Disease Committee, “Diseases Associated With Exposure to Silica and Non-fibrous Silicate Minerals,” 112 Arch. Path. & Lab. Med. 673, 707 (1988) (“Epidemiologic studies have been conducted in an effort to assess the role of silica exposure in the pathogenesis of lung cancer. *** Thus, the results are inconclusive … .”)

Arthur Frank, “Epidemiology of Lung Cancer, in J. Roth, et al., Thoracic Oncology, Chap. 2, at p. 8 (Table 2-1), 11 (Phila. 1989) (omitting silica from list of lung carcinogens) (“The question of the relationship of coal mining to the development of lung cancer has been frequently considered. Most evidence points to cigarette smoking among coal miners as the major causative factor in the development of lung cancer, and neither a recent84 nor a British study of lung cancer among coal miners has found any relationship to occupational exposure.”)

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).

Another Confounder in Lung Cancer Occupational Epidemiology — Diesel Engine Fumes

June 13th, 2012

Researchers obviously need to be aware of, and control for, potential and known confounders.  In the context of investigating the etiologies of lung cancer, there is a long list of potential confounding exposures, often ignored in peer-reviewed papers, which focus on one particular outcome of interest.  Just last week, I wrote to emphasize the need to account for potential and known confounding agents, and how this need was particularly strong in studies of weak alleged carcinogens such as crystalline silica.  See Sorting Out Confounded Research – Required by Rule 702.  Yesterday, the World Health Organization (WHO) added another “known” confounder for lung cancer epidemiology:  diesel fume.

According to the International Agency for Research on Cancer (IARC), a division of the WHO, a working group of international experts voted to reclassify diesel engine exhaust as a “Group I” carcinogen.  IARC: Diesel engines exhaust carcinogenic (2012).  This classification means, in IARC parlance, that ” there is sufficient evidence of carcinogenicity in humans. Exceptionally, an agent may be placed in this category when evidence of carcinogenicity in humans is less than sufficient but there is sufficient evidence of carcinogenicity in experimental animals and strong evidence in exposed humans that the agent acts through a relevant mechanism of carcinogenicity.”  The Group was headed up by Dr. Christopher Portier, who is the director of the National Center for Environmental Health and the Agency for Toxic Substances and Disease Registry at the Centers for Disease Control and Prevention.  Id.

The reclassification removes diesel exhaust from its previous categorization as a Group 2A carcinogen, which is interpreted “as probably carcinogenic to humans.”  Diesel exhaust has been on a high-priority list for re-evaluation since 1998, as result of epidemiologic research from many countries.  The Working Group specifically found that there was sufficient evidence to conclude that diesel exhaust is a cause of lung cancer in humans, and limited evidence to support an association with bladder cancer.  The Group rejected any change in classification of gasoline engine exhaust from its current IARC rating as “possibly carcinogenic to humans. (Group 2B).”

Unlike other IARC Working Group decisions (such as crystalline silica), which were weakened by close votes and significant dissents, the diesel Group’s conclusion was unanimous.  The diesel Group appeared to be impressed by two recent studies of lung cancer in underground miners, released in March 2012.  One study was in a large cohort, conducted by NIOSH, and the other was a nested case-control study, conducted by the National Cancer Institute (NCI).  See Debra T. Silverman, Claudine M. Samanic, Jay H. Lubin, Aaron E. Blair, Patricia A. Stewart , Roel Vermeulen, Joseph B. Coble, Nathaniel Rothman, Patricia L. Schleiff , William D. Travis, Regina G. Ziegler, Sholom Wacholder, Michael D. Attfield, “The Diesel Exhaust in Miners Study: A Nested Case-Control Study of Lung Cancer and Diesel Exhaust,” J. Nat’l Cancer Instit. (2012)(in press and open access); and Michael D. Attfield, Patricia L. Schleiff, Jay H. Lubin, Aaron Blair, Patricia A. Stewart, Roel Vermeulen, Joseph B. Coble, and Debra T. Silverman, “The Diesel Exhaust in Miners Study: A Cohort Mortality Study With Emphasis on Lung Cancer,” J. Nat’l Cancer Instit. (2012)(in press).

According to a story in the New York Times, the IARC Working Group described diesel engine exhaust as “more carcinogenic than secondhand cigarette smoke.”  Donald McNeil, “W.H.O. Declares Diesel Fumes Cause Lung Cancer,” N.Y. Times (June 12, 2012).  The Times also quoted Dr. Debra Silverman, NCI chief of environmental epidemiology, at length.  Dr. Silverman, who was the lead author of the nested case-control study cited by the IARC Press Release, noted that her large study showed that long-term heavy exposure to diesel fumes increased lung cancer risk seven fold. Dr. Silverman described this risk as much greater than that thought to be created by passive smoking, but much smaller than smoking two packs of cigarettes a day.  She stated that “totally” supported the IARC reclassification, and that she believed that governmental agencies would use the IARC analysis as the basis for changing the regulatory classification of diesel exhaust.

Silverman’s nested case-control study appears to have been based upon careful diesel exhaust exposure information, as well as smoking histories.  The study also searched and analyzed for other potential confounders, which might be expected to be involved in underground mining:

“Other potential confounders [ie, duration of cigar smoking; frequency of pipe smoking; environmental tobacco smoke; family history of lung cancer in a first-degree relative; education; body mass index based on usual adult weight and height; leisure time physical activity; diet; estimated cumulative exposure to radon, asbestos, silica, polycyclic aromatic hydrocarbons (PAHs) from non-diesel sources, and respirable dust in the study facility based on air measurement and other data (14)] were evaluated but not included in the final models because they had little or no impact on odds ratios (ie, inclusion of these factors in the final models changed point estimates for diesel exposure by ≤ 10%).”

Silverman, et al., at 4.  The absence of an association between lung cancer and silica exposure is noteworthy in a such a large study of underground miners.