Asbestos is the collective name for a group of naturally occurring silicates whose heat-resistant and structural properties are useful in construction and insulating and other materials on board ships, in automobile brakes, and in some textiles. There are two main classes of asbestos: serpentine (which includes chrysotile) and amphibole (which includes amosite, crocidolite, anthophyllite, tremolite, and actinolite). Chrysotile fiber is the most common asbestos used worldwide.
In most developed countries, asbestos use has declined over the past several decades, but asbestos can still be found in old building materials and some products. More widespread asbestos use continues primarily in some developing countries. Due to the long latency between exposure and disease, asbestos-related disease continues to occur.
Prior occupational exposure remains the predominant cause of asbestos-related disease. Asbestos is also present in low levels in the air, water, and soil; this low level of environmental exposure is generally not a significant contributor to human disease.
Asbestos-related disorders are caused by inhalation of asbestos fibers, such as when friable asbestos-containing material is disturbed. Asbestos can cause nonmalignant and malignant disease.
Nonmalignant disease includes
Asbestosis
Asbestos-related pleural plaque formation and pleural thickening
Benign asbestos pleural effusion (BAPE)
Asbestosis is a form of interstitial pulmonary fibrosis caused by asbestos exposure.
Asbestos-related pleural plaques are the most common manifestation of asbestos exposure. The latency period from exposure to onset is 20 to 30 years. Often pleural plaques are asymptomatic, although because they result from asbestos exposure, they increase the risk of other asbestos-related lung disease.
Asbestos-related pleural thickening is characterized by diffuse, extensive thickening of the visceral pleura with areas of adherence to the parietal pleura and obliteration of the pleural space. Diffuse pleural thickening can occur after nonmalignant pleural effusions and can be associated with restrictive deficits, dyspnea, and chest pain.
Benign asbestos pleural effusions (BAPE) are small and often unilateral and hemorrhagic pleural effusions. These generally occur earlier than other asbestos-related lung disease, usually within 10 years of exposure. BAPE can be asymptomatic or present with fever and pleuritic-type chest pain.
Malignant disease includes
Lung cancer
Mesothelioma
Lung cancer is the most common type of cancer associated with asbestos exposure. The latency from exposure to disease onset is typically 20 to 30 years. Risk of lung cancer due to asbestos exposure increases with larger cumulative exposures. Though asbestosis is an indicator of high-level exposure, lung cancer can occur without asbestosis. Smoking and asbestos exposure have a well-known multiplicative effect on the risk of lung cancer.
Mesothelioma, a malignant tumor of the pleura and/or peritoneum, is characterized by a long latency from exposure to disease onset, with a median of approximately 40 years. Although most mesotheliomas are occupational in origin, they can also develop after environmental exposure or take-home exposure (ie, when a worker brings asbestos home through contaminated belongings).
(See also Overview of Environmental and Occupational Pulmonary Disease.)
