Parenchymal and Airway Diseases Caused by Asbestos

Andreea L. Antonescu-Turcu; Ralph M. Schapira

Disclosures

Curr Opin Pulm Med. 2010;16(2):155-161. 

In This Article

Abstract and Introduction

Abstract

Purpose of review: The extensive industrial use of asbestos for many decades has been linked to development of benign and malignant pleuropulmonary disease. This review summarizes newer evidence and ongoing controversies that exist in the literature regarding asbestos-related parenchymal and airway diseases.
Recent findings: Asbestosis represents a significant respiratory problem despite the improvement in the workplace hygiene and a decrease in use of asbestos. The management of asbestosis remains challenging as currently there is no specific treatment. The role of asbestos exposure alone as a cause of chronic airway obstruction remains uncertain. The relationship between lung cancer and asbestos exposure alone and in combination with smoking has also been investigated. The benefit of screening for asbestos-related pleuropulmonary disease remains uncertain as does the use of computed tomography scanning for the purpose of screening.
Summary: Future studies will help clarify the clinical issues and shape screening strategies for asbestos-exposed individuals.

Introduction

Asbestos is the term for a heterogeneous group of natural fiber minerals composed of hydrated magnesium silicates. According to the National Research Council, the term asbestos is a 'commercial–industrial' characterization rather than a mineralogical term. It refers to well developed and hairlike long-fibered varieties of certain minerals that satisfy particular industrial needs.[1] Based on the fiber structure and chemical composition, asbestos fibers are divided into two categories: serpentine (chrysotile) and amphibole (crocidolite, amosite, tremolite, anthophyllite and actinolite).

The International Labour Organization (ILO, a UN agency) reports that at least 100 000 people worldwide die yearly from complications of asbestos exposure (http://www.ilo.org/public_english/protection/safework/health/resolution_on_asbestos.pdf; last accessed 18 October 2009). In the United States, the Environmental Protection Agency proposed a ban on the use of asbestos, which to this day has never been fully implemented due to legal challenges. Even as the use of asbestos has decreased in many industrial countries, the mortality from asbestosis has increased steadily and currently represents the most common cause of death due to pneumoconiosis in the United States.[2] Given the use of asbestos for more than 100 years and long lag between exposure and development of pleuropulmonary disease, many people have been affected by an 'asbestos epidemic.' The adverse health effects of asbestos have resulted in runaway asbestos litigation in the United States. More than 730 000 claims have been filed since litigation began and as many as three million are possible before it ends. Companies have paid an estimated $70 billion in asbestos-related settlements and legal costs since the 1970s.

Asbestos exposure is associated with a wide spectrum of pleuropulmonary disorders including asbestosis (Figs 1 and 2), pleural fibrosis (plaques or diffuse thickening) (Fig. 3), nonmalignant pleural effusion, airflow obstruction and malignancies (bronchogenic carcinoma and malignant pleural mesothelioma – Fig. 4).[3] According to the 2004 American Thoracic Society (ATS) criteria, the diagnosis of nonmalignant asbestos-related disease is based on three criteria: evidence of structural pathology consistent with asbestos-related disease as documented by imaging or histology; evidence of causation by asbestos as documented by the occupational and environmental history, markers of exposure (usually pleural plaques), recovery of asbestos bodies or other means and exclusion of alternative plausible causes for the clinical findings.[4]

Figure 1.

Early asbestosis
There is evidence of irregular opacities in the lower lung fields that may be classified as 0/1 or approaching 1/0 according to the International Labor Organization (ILO). There is also evidence of pleural thickening. The ILO classification defines chest radiographs that are suggestive but not presumptively diagnostic as 0/1 and those that are presumptively diagnostic but not unequivocal as 1/0. Reprinted with permission from [4].

Figure 2.

Advanced asbestosis
There is evidence of fibrotic bands superimposed on a background of reticular opacities, shaggy heart border, pleural plaques and blunting of the costophrenic angle. Reproduced with permission from [4].

Figure 3.

Pleural plaques on a chest radiograph
There is evidence of minimal parenchymal disease. Reproduced with permission from [4].

Figure 4.

Clinical and computed tomographic (CT) features of malignant mesothelioma
(a) shows a subcutaneous extension of malignant mesothelioma. (b) shows the CT appearance of pleural mesothelioma consisting predominantly of a pleural mass, and (c) shows its CT appearance as a diffuse, encircling rind of tumor. Reproduced with permission [3].

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