Fiber types, asbestos potency, and environmental causation: a peer review of published work and legal and regulatory scientific testimony

Our plain-English summary of Fiber types, asbestos potency, and environmental causation: a peer review of published work and legal and regulatory scientific testimony, by D. Egilman (International Journal of Occupational and Environmental Health, 2009).

The study

• Author: D. Egilman
• Journal: International Journal of Occupational and Environmental Health
• Published: 2009;15(2):202-28
• Cited by: 20 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Scientific evidence and analysis offered in litigation and public policy testimony have an important role in occupational and environmental health, but are not subject to peer review. Critique and commentary, attempts at reproduction of results, and review of data offered in such testimony is essential. Peer review of such testimony should become part of the domain of medical and scientific journals. This paper is an effort to peer review the use of certain scientific methods in tort litigation and in testimony before regulatory agencies. In this issue of IJOEH, Azuma et al. show that background asbestos exposures can be considered to have caused mesothelioma. In contrast, epidemiologic studies and testimony by Teta et al. and Price and Ware, and pathologic studies and testimony by Roggli and others, claim that background exposures are benign. These are fatally flawed because of methodological and analytic errors.

In plain English

This article was a commentary. The author described it as an effort to peer review scientific methods used in published work and in testimony given in asbestos lawsuits and before regulators. The author argued that studies by Teta et al. and Price and Ware, which used national SEER cancer-registry data to estimate a 'background' mesothelioma rate, could not settle questions of exposure because SEER holds no exposure information. The author also criticized fiber-potency estimates that relied on what the author called unreliable exposure data, and lung fiber-count studies and testimony by Roggli and colleagues. Reanalyzing data published by Srebro, Roggli and Samsa, the author reported that a two-tailed test that accounts for left-censored data showed no difference in fiber counts between their mesothelioma cases and their 'controls'. The author argued that the microscope method used in that work misses thin chrysotile fibers. The article also listed mesothelioma cases in women with household exposure tied mainly to Virginia shipyards. Of the 38 people the text describes, 82% were exposed through their spouses. The author concluded that reviewing scientific testimony is at least as important as peer review of published research.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Commentary and critical review (described by the author as a peer review of published work and of legal and regulatory testimony), including a reanalysis of published data and a list of cases
• Who was studied: Published studies and testimony reviewed: SEER-based studies by Teta et al. and Price and Ware; meta-analyses by Hodgson and Darnton and by Berman and Crump; lung fiber studies and testimony by Roggli and colleagues (Srebro, Roggli and Samsa 1995: 18 mesothelioma cases and 19 controls; Butnor, Sporn and Roggli 2003: 10 brake mechanics). Also a table of mesothelioma cases in women with domestic or residential exposure linked to Virginia shipyards.
• Exposure: 'Background' (environmental) asbestos exposure; chrysotile compared with amphiboles (amosite, crocidolite, tremolite); brake work; household (para-occupational) exposure from shipyard workers
• Main results:
  • In the table of household-exposure cases in women, the text reports 38 people. Year of birth ranged from 1905 to 1952 and age at death from 43 to 90, with 92% older than 50. 82% were exposed via their spouses and 21% by their father or by both father and spouse.
  • Two of the exposed cases in this list (born in 1952) fit Teta et al.'s criteria for non-exposure.
  • The author argued that SEER data cannot establish whether people were exposed to asbestos, because exposure information can only come from patient histories or pathologic studies.
  • Reanalyzing the Srebro, Roggli and Samsa data with a two-tailed test that accounts for left-censored data, the author reported that fiber counts of controls and mesothelioma cases were not different.
  • Even using Roggli's statistical method and after deleting the excluded control, the author found no significant difference between cases and controls for asbestos bodies, total fibers and chrysotile. The author was unable to repeat the original statistical results.
  • The author reported that several of the Srebro, Roggli and Samsa controls likely had occupational asbestos exposure (for example manual laborers, Air Force, hospital workers, a garage owner).
  • The author argued that Roggli's scanning electron microscope method, set at a magnification of only 1000, misses chrysotile fibers less than 0.15 μm in diameter and so undercounts chrysotile.
  • The author argued that fiber-potency risk assessments (such as Hodgson and Darnton, and Berman and Crump) rest on unreliable exposure estimates.
• The authors' conclusion: The author concluded that reviewing scientific ideas presented in court and at hearings is at least as important as peer review of published research. Elsewhere in the text the author argued that SEER-based ecological epidemiology cannot give useful information on individual risk or on disease causation.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Mesothelioma.

Medical terms in this study, explained in our Lexicon: Causation, Tort, Asbestos Exposure, Mesothelioma, Background Exposure.

Related studies

• Scientific method questioned — D.J. Paustenbach (2006)
• Asbestos: Socio-legal and Scientific Controversies and Unsound Science in the Context of the Worldwide Asbestos Tragedy - Lessons to be Learned — X. Baur (2016)
• South African experience with asbestos related environmental mesothelioma: is asbestos fiber type important? — N. White, G. Nelson, et al. (2008)
• Protest and survive, the U.K. Construction Safety Campaign: a case study of workers' and victims' family action and legal and regulatory inaction on construction health and safety — M. Holder, T. O'Brien (2007)
• Perineal talc use and ovarian cancer risk: a case study of scientific standards in environmental epidemiology — M. Huncharek, J. Muscat (2011)
• Scientific controversy and asbestos: making disease invisible — L. Braun, A. Greene, et al. (2003)

Browse more research in International Journal of Occupational and Environmental Health, or return to medical research.