While all forms of asbestos have been determined to be carcinogenic to humans by the International Agency for Research on Cancer (IARC) as well as other authoritative bodies, the relative carcinogenic potency of chrysotile continues to be argued, largely in the context of toxic tort litigation. Relatively few epidemiologic studies have investigated only a single form of asbestos; however, one study that included an asbestos textile plant located in Marshville, North Carolina that processed chrysotile asbestos was used by the United States Environmental Protection Agency (EPA) in 2020 to help inform the agency’s chrysotile asbestos risk assessment. During the EPA proceedings toxic tort defense consultants submitted comments to the EPA docket and made public presentations asserting that the Marshville plant had processed amphibole asbestos types and should not be used for the chrysotile risk assessment. A detailed evaluation of defense consultant assertions and supporting information and a full assessment of the available information concerning asbestos types used at the Marshville plant was undertaken. The preponderance of evidence continues to support the conclusion that neither amosite nor crocidolite were likely to have been processed in the Marshville textile plant. Defense consultants’ assertions about chrysotile use are not supported by the preponderance of evidence and constitute an example of manipulation of information to cast uncertainty and doubt rather than to seek truth and contribute to the body of scientific evidence.
1 INTRODUCTION
While all forms of asbestos have been determined to be carcinogenic to humans by the International Agency for Research on Cancer (IARC) as well as other authoritative bodies, the relative carcinogenic potency of chrysotile continues to be argued, largely in the context of toxic tort litigation. With funding provided by the National Institute for Occupational Safety and Health (NIOSH) we conducted a number of studies of four historically important asbestos textile plants located in North Carolina. According to available records, only chrysotile was used in these plants except for a separate operation in one plant, where a limited amount of amosite was carded, twisted, and woven between approximately 1963 and 1976. The North Carolina studies included retrospective exposure reconstruction using airborne dust measurements, airborne fiber size determinations by transmission electron microscopy, a cohort mortality study, and lung cancer and mesothelioma exposure-response analyses. All studies were published in the peer-reviewed literature.
Since publication of the North Carolina studies asbestos defense legal firms and their paid consultants have launched a coordinated attack in an attempt to discredit our work. The primary contention of defense consultants is that amosite and/or crocidolite asbestos was used or processed at the Marshville, North Carolina asbestos textile plant, while our review of all available records did not find use of amphibole asbestos at Marshville. The attacks culminated with written comments and a presentation by Dr. David H. Garabrant to the United States Environmental Protection Agency (EPA), Office of Chemical Safety and Pollution Prevention and Toxics in 2020 with regard to a Draft Risk Evaluation for Asbestos. Dr. Garabrant’s slide presentation and subsequent written comments actually closely parallel a presentation made by defense attorney Kurt L. Rasmussen (Rasmussen, Willis, Dickey & Moore, LLC) at a Defense Research Institute (DRI) Defense Practice Seminar in 2013. Dr. Garabrant’s comments to the EPA docket were subsequently summarized in a publication by defense consultants with little, if any, evaluation of Dr. Garabrant’s comments and the supporting information.
The purpose of this commentary is to present a detailed accounting of what is known regarding the processes in place at the Marshville, North Carolina asbestos textile plant and types of asbestos used there. We also critically review the conclusions drawn by defense attorneys and Dr. Garabrant, and the data that they claim to support their conclusions. This presentation only addresses the Marshville plant and not the details of the EPA chrysotile asbestos risk assessment.
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