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Published on: October 2, 2015
Malignant mesothelioma and occupational exposure to asbestos: a clinicopathological correlation of 1445 cases
Victor L Roggli1, Anupama Sharma, Kelly J Butnor
1Department of Pathology, Durham Veterans Administration and Duke University Medical Center, North Carolina 27710, USA.
Abstract:
Asbestos exposure is indisputably associated with development of mesothelioma. However, relatively few studies have evaluated the type of occupational exposure in correlation with asbestos fiber content and type. This study reports findings in 1445 cases of mesothelioma with known exposure history; 268 of these also had fiber burden analysis. The 1445 cases of mesothelioma were subclassified into 23 predominant occupational or exposure categories. Asbestos body counts per gram of wet lung tissue were determined by light microscopy. Asbestos fiber content and type were determined by scanning electron microscopy and energy dispersive x-ray analysis. Results were compared with a control group of 19 lung tissue samples. Ninety-four percent of the cases occurred among 19 exposure categories. Median asbestos body counts and levels of commercial and noncommercial amphibole fibers showed elevated levels for each of these 19 categories. Chrysotile fibers were detectable in 36 of 268 cases. All but 2 of these also had above-background levels of commercial amphiboles. When compared to commercial amphiboles, the median values for noncommercial amphibole fibers were higher in 4 of the 19 exposure groups. Most mesotheliomas in the United States fall into a limited number of exposure categories. Although a predominant occupation was ascertained for each of these cases, there was a substantial overlap in exposure types. All but 1 of the occupational categories analyzed had above-background levels of commercial amphiboles. Commercial amphiboles are responsible for most of the mesothelioma cases observed in the United States.
Insights
Most mesothelioma cases in the U.S. stem from a few occupational exposures. Commercial amphiboles are the primary cause, with elevated fiber levels found across many asbestos exposure types.
Area of Science:
- Occupational Health
- Environmental Toxicology
- Pathology
Background:
- Asbestos exposure is a known cause of mesothelioma.
- Limited research exists on occupational exposure types linked to asbestos fiber content and type.
Purpose of the Study:
- To analyze the correlation between mesothelioma cases and specific occupational exposures.
- To determine asbestos fiber burden and type in relation to exposure history.
Main Methods:
- Analysis of 1445 mesothelioma cases with exposure history.
- Fiber burden analysis (asbestos body counts, fiber content, and type) in 268 cases.
- Comparison with 19 control lung tissue samples using light microscopy, scanning electron microscopy, and energy dispersive x-ray analysis.
Main Results:
- 94% of cases fell into 19 occupational categories.
- Elevated asbestos body counts and amphibole fiber levels were found in these categories.
- Commercial amphiboles were present in nearly all analyzed occupational categories and are linked to most U.S. mesothelioma cases.
Conclusions:
- Mesothelioma in the U.S. is concentrated in a limited number of occupational exposure categories.
- Commercial amphiboles are the predominant fiber type responsible for mesothelioma.
- Understanding specific occupational exposures is crucial for mesothelioma prevention.
