Current controversies regarding the role of asbestos exposure in the causation of malignant mesothelioma: the need for an evidence-based approach to develop medicolegal guidelines

Our plain-English summary of Current controversies regarding the role of asbestos exposure in the causation of malignant mesothelioma: the need for an evidence-based approach to develop medicolegal guidelines, by A.M. Marchevsky, M.R. Wick (Annals of Diagnostic Pathology, 2003).

The study

• Authors: A.M. Marchevsky, M.R. Wick
• Journal: Annals of Diagnostic Pathology
• Published: 2003;7(5):321-32
• Type of article: Review
• Cited by: 19 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Asbestos is a group of fibrous silicate minerals that includes two mineralogic groups: amphiboles and serpentines. While the carcinogenic role of amphiboles (eg, crocidolite and amosite) is well established, medical "experts" that tend to strongly advocate their views currently argue in medicolegal cases multiple specific issues regarding the carcinogenicity of asbestos fibers. For example, it is controversial whether chrysotile causes malignant mesothelioma (MM); what are the specific carcinogenic thresholds for amphiboles and chrysotile; what occupations are truly at risk to develop MM as a result of asbestos exposure; what is the role of chrysotile in the development of peritoneal MM; how to assign causation in individuals exposed to multiple industrial products containing variable concentrations of various asbestos fibers; and, what criteria should be used to accept causation in household exposure cases and others. The causation criteria currently acceptable in U.S. courts are surprisingly flexible and subject to variable interpretation by medical "experts." At a time where thousands of individuals are claiming causation of MM by asbestos exposure, there is a need to develop more specific causation guidelines based on scientific evidence. Evidence-based medicine has been proposed as a new approach to the study, teaching, and the practice of medicine and has been used as a process of systematically reviewing the relevant studies in the literature to assess their scientific validity and development of guidelines. This article summarizes some of the current controversies regarding the role of asbestos exposure in the causation of MM and suggests the need for future evidence-based medicine-type studies to develop causation guidelines that could be used consistently during litigation.

In plain English

This review article discussed disputes, mainly as argued in U.S. asbestos lawsuits, about when asbestos exposure causes malignant mesothelioma. It reported no new data. The authors described Bradford Hill's criteria for judging causation and criticized the 1997 Helsinki criteria as giving only very general and internally contradictory answers to questions raised in court. They then posed 12 questions. These included the minimum exposure duration needed, whether chrysotile causes pleural or peritoneal mesothelioma, which occupations are at risk, paraoccupational or household exposure, dose thresholds, and how to apportion causation among several products. For several of these questions, they stated that no scientific data or established method exists. Citing meta-analyses by Hodgson and associates, they gave the relative carcinogenicity of crocidolite, amosite and chrysotile for mesothelioma as 500:100:1. The authors concluded that courts need objective guidelines on asbestos and mesothelioma causation that can be used consistently. They also concluded that multidisciplinary studies grounded in evidence-based medicine should be done to develop those guidelines. They called the article a brief consideration of a complex topic.

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: Narrative review article (no original data)
• Who was studied: No study population. The article discussed published literature and the arguments made in U.S. medicolegal cases about asbestos and malignant mesothelioma.
• Exposure: Amphibole asbestos (crocidolite, amosite, tremolite) and chrysotile, including occupational, paraoccupational and household exposures
• Main results:
  • The authors judged that the 1997 Helsinki criteria give only very general and internally contradictory answers to many questions posed in the courts.
  • As a first step toward an evidence-based medicine approach, the authors set out specific questions (12 in total) about mesothelioma causation.
  • On the minimum duration of exposure needed to develop mesothelioma, the authors stated that they knew of no scientific data that could answer the question consistently.
  • The authors stated that no established scientific method exists to apportion causation among different asbestos exposures in mesothelioma cases.
  • The authors stated that there are no current scientific methods to establish individual susceptibility to mesothelioma.
  • Citing other studies (meta-analyses by Hodgson and associates), the authors reported the relative carcinogenicity of crocidolite, amosite and chrysotile for mesothelioma as 500:100:1.
  • Citing other epidemiologic studies, the authors stated that painters, construction workers and auto mechanics lack significantly increased risks of mesothelioma.
  • Citing fiber-burden analyses by others, the authors described two populations of mesothelioma patients. One group had background lung asbestos levels and the other had substantially higher fiber burdens.
• The authors' conclusion: The authors concluded that courts need objective guidelines on mesothelioma causation by asbestos that can be applied consistently and fairly. They called for multidisciplinary studies grounded in evidence-based medicine to establish these guidelines.
• Limitations the authors state:
  • The authors described the article as a brief consideration of a complex topic.
  • The authors stated that a detailed discussion of experimental animal models was beyond the scope of the review.

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: Asbestos Exposure, Causation, Mesothelioma, Silicate, Amphibole Group, Serpentine Group, Carcinogenic, Crocidolite.

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