US EPA

6864115 

Journal Article 

Abstract 

Mesothelioma with no evidence of commercial amphibole asbestos exposure - 35 cases with chrysotile, non-commercial amphibole or asbestiform talc by lung fiber burden analysis 

Sanyal, S; Abraham, JL; Crawford, JA; Burnett, B 

2017 

Yes 

American Journal of Respiratory and Critical Care Medicine
ISSN: 1073-449X
EISSN: 1535-4970 

195 

A3863 

English 

WOS:000400372503354 

https://www.atsjournals.org/doi/abs/10.1164/ajrccm-conference.2017.195.1_MeetingAbstracts.A3863
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RATIONALE: Mesothelioma (meso) is a signature disease caused by asbestos, and all asbestos fiber types are recognized as capable of causing meso, yet controversy remains about cases with no exposure to commercial amphiboles (comA). Lung fiber burden analysis (FBA) reveals types and concentrations of mineral fibers in lung parenchyma. Meso cases with well-documented FBA confirming exposure to chrysotile (CH) and non-commercial amphiboles (non-comA) (tremolite-actinolite-anthophyllite), with no evidence of comA exposure are rare or lacking. Previous FBA on friction-material workers are limited by inability to reliably detect CH owing to use of low magnification. Also, some meso cases classified as 'idiopathic' may not have had adequate FBA. We examined our FBA database to investigate this issue. METHODS: From our database of >1200 FBA of >500 individual patients, done from 1981-2015, using our standard SEM protocol at 4000x-10,000x magnification, we found 167 cases showing no detectable comA. From these we selected confirmed meso cases, excluding cases with detection limits (DL) too high to exclude comA elevated above background. Analyses included DL between 1000-2000 fibers >5um length per gram of wet lung tissue (f/g)]. Cases with history of highly probable comA exposure were also excluded. RESULTS: 35 meso cases fit our selection criteria. There were three main groups: those with friction product exposure (N=7), history of asbestiform talc exposure (N=11), and those with variable exposures not including talc or friction products (N=17). CH fibers were frequently not detected in low magnification analyses when readily identified at higher magnifications. The Table summarizes some of the results. CH concentration was greater than non-comA and talc except in the talc group, although all types were highest in the talc group. CONCLUSIONS: These results show the difficulty in detecting mesothelioma cases which have no evidence for commercial amphibole exposures, and the complexity of lung burdens of several asbestiform fiber types. Adequate FBA data is vital in demonstrating such cases, as asbestos fibers may be undetectable with FBA lacking sufficient sensitivity for fibers by concentration and dimensions. CH is often not detected at low magnification analysis when detected at high magnification. Asbestiform talc and anthophyllite asbestos coexist and are not easily distinguishable. CH concentrations may be higher in persons with asbestiform talc exposure as well. Our data supports the existence of mesothelioma cases related to exposure to asbestiform talc and to chrysotile products alone, and that automotive friction workers comprise a substantial fraction of these cases. 

American Thoracic Society 2017 International Conference 

Washington, DC 

May 19-24, 2017