A Critique of Helsinki Criteria for Using Lung Fiber Levels to Determine Causation in Mesothelioma Cases.

Asbestos is a known human carcinogen and the chief known cause of mesothelioma. In 1997, a group of experts developed the Helsinki Criteria, which established criteria for attribution of mesothelioma to asbestos. The criteria include two methods for causation attribution: 1) a history of significant occupational, domestic, or environmental exposure and/or 2) pathologic evidence of exposure to asbestos. In 2014, the Helsinki Criteria were updated, and these attribution criteria were not changed. However, since the Helsinki Criteria were first released in 1997, some pathologists, cell biologists, and others have claimed that a history of exposure cannot establish causation unless the lung asbestos fiber burden exceeds "the background range for the laboratory in question to attribute mesothelioma cases to exposure to asbestos." This practice ignores the impact on fiber burden of clearance/translocation over time, which in part is why the Helsinki Criteria concluded that a history of exposure to asbestos was independently sufficient to attribute causation to asbestos. After reviewing the Helsinki Criteria, we conclude that their methodology is fatally flawed because a quantitative assessment of a background lung tissue fiber level cannot be established. The flaws of the Helsinki Criteria are both technical and substantive. The 1995 paper that served as the scientific basis for establishing background levels used inconsistent methods to determine exposures in controls and cases. In addition, historic controls cannot be used to establish background fiber levels for current cases because ambient exposures to asbestos have decreased over time and control cases pre-date current cases by decades. The use of scanning electron microscope (SEM) compounded the non-compatibility problem; the applied SEM cannot distinguish talc from anthophyllite because it cannot perform selected area electron diffraction, which is a crucial identifier in ATEM for distinguishing the difference between serpentine asbestos, amphibole asbestos, and talc.

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Copyright: © 2021 The Author(s).

Déclaration de conflit d'intérêts

Dr. David Egilman serves as an expert witness in litigation at the request of people who claim injuries resulting from the use of talcum powders. He has also served as an expert witness at the request of companies who have been sued for exposure to asbestos from their mines or products. He was not compensated for work on this commentary. No party to these litigations reviewed this commentary or had input into its content. Dr. Mark Rigler serves as an expert witness in litigation at the request of people who claim injuries resulting from the use of talcum powders. He was not compensated for work on this commentary. Dr. Theresa Emory has testified in asbestos litigation, primarily for plaintiffs. Triet Tran works for Dr. Egilman.