Description

• Pneumoconiosis caused by inhalation of asbestos fibers often through environmental or occupational exposure
• Characterized by slowly progressive pulmonary fibrosis
• Clinical presentation exists along a spectrum ranging from asymptomatic to severe pulmonary disease requiring palliative care.
• Associated with an increased risk of pulmonary malignancy
• Synonym(s): asbestos pneumoconiosis

Epidemiology

• The physical properties of asbestos made it popular for use in a variety of commercial industries beginning in the early 1900s.
• Widespread use led to occupational and environmental exposure for millions of people around the globe.
• In the United States, an estimated 1.3 million people who work in maintenance and construction are at risk for exposure to asbestos (1).

Etiology and Pathophysiology

• Asbestos refers to naturally occurring silicate fibers.
• Exposure occurs when environments and materials containing asbestos fibers are disturbed and released into the air.
• Inhalation of asbestos fibers is thought to result in asbestosis when (2):
  • Inhaled particles are retained within the pulmonary system.
  • Activation of various immune mediators occurs to address retained fibers and results in inflammation.
  • Ongoing inflammation leads to breakdown of normal cellular structure(s).
  • Fibroblast proliferation and remodeling ultimately result in fibrosis.
• The disease can continue to progress even if exposure is not ongoing.
• Latency period from initial exposure to symptom development can range from 10 to 40 years (1).
• The effects of asbestos inhalation are dependent on cumulative dose, time since exposure, and the type of asbestos fibers inhaled (2).
• Symptoms may be related to impaired gas exchange and/or a pattern of restrictive lung disease.

Genetics

• Genetic polymorphisms have been implicated.
• Familial mesothelioma has been reported.

Risk Factors

• High-risk industries and occupations for asbestos exposure include but are not limited to the following:
  • Automobile repair
  • Aviation
  • Construction
  • Maintenance
  • Manufacturing
  • Mill work and mining
  • Plumbing
  • Shipbuilding and maintenance
  • Rail transportation employees
• High-risk environmental exposures can be seen with the following:
  • Routine exposure to family members in high-risk occupations
  • Residing in highly industrialized areas
  • Repeated exposure to structures with asbestos-containing materials undergoing demolition or maintenance
• Asbestosis increases lung cancer risk and, with smoking, has an additive effect (3).

General Prevention

• In the United States, asbestos is federally regulated by the Occupational Safety and Health Administration.
• Primary responsibility of employers is to provide safe work environment.
• Exposure control: substitution of safer materials or adoption of control technologies
• During high-exposure periods, such as building repair, use fit-tested personal respirators for workers.
• To limit exposure to others in their household, those who work with asbestos should leave their clothing at work, if possible. Work clothes should be washed and stored separately from other clothing.

Commonly Associated Conditions

In addition to asbestosis, inhalation of asbestos is associated with other lung-related disorders, including the following:

• Benign pleural plaques
• Benign pleural effusions
• Lung cancer
• Malignant mesothelioma