What is Silicosis?
Silicosis, an occupational lung disease, is a respiratory disease caused by inhalation of silica dust. When crystalline silica (a component of silica dust) is inhaled, it causes inflammation of the lung tissue. This inflammation leads to scar tissue formation on the lungs, also known as nodules, which obstructs the flow of oxygen into the lungs and into the bloodstream. Before it was identified and named in the 1930s, silicosis was known by a variety of names, such as dust consumption, grinder's asthma, grinder's rot, grit consumption, mason's disease, miner's asthma, miner's phthisis, potter's rot, rock tuberculosis, and stonemason's disease.

Types of Silicosis
There are three types of silicosis: chronic silicosis, accelerated silicosis, and acute silicosis.

  • Chronic silicosis - occurs due to long-term exposure to low amounts of silica.
  • Accelerated silicosis - also known as progressive massive fibrosis; occurs more quickly than chronic silicosis, usually due to exposure to larger amounts of silica over a shorter period of time.
  • Acute silicosis - occurs due to short-term exposure to extremely large amounts of silica. Acute silicosis can develop within several weeks or up to five years after exposure. Silicosis has also been linked to adverse health effects such as tuberculosis and lung cancer.

Silica Exposure
Silica, or silicon dioxide, is a naturally occurring mineral that is composed of one silicon atom and two oxygen atoms. When silica molecules line up and create a repeating pattern they form a crystal (crystalline silica). Different crystal patterns are given different names, such as quartz, cristobalite, and tridymite, to name a few. People who work with quartz and other types of crystalline silica are at an increased risk of silica exposure.

Silica exposure most often occurs in people who work in construction, mining, sandblasting, stonecutting, abrasives manufacturing, and in people who work with glass, pottery, foundries or on railroads.

Silicosis Prevention
Although there is no cure for silicosis, it can be prevented with occupational safety measures. There has been a marked decrease in the number of silicosis cases since the Occupational Safety and Health Administration (OSHA) implemented regulations that require the use of protective equipment when working with silica dust.

Silicosis Health Effects
Silicosis is an occupational lung disease characterized by inflammation and scarring of the lung tissue. The formation of scar tissue inhibits the flow of oxygen into the lungs and into the bloodstream.

The earliest symptoms of silicosis may include:

  1. Shortness of breath
  2. Coughing
  3. Wheezing
  4. Fatigue
  5. Chest pain
  6. Loss of appetite
  7. Fever
  8. Occasional bluish skin at ear lobes or lips

As the lung disease progresses, more severe symptoms such as pulmonary and cardiac impairment will occur. In some cases, pulmonary function will be impaired to the point where the patient will need to be supplied with oxygen.

 Silicosis Health Problems
In addition to the symptoms listed above, silicosis patients are at an increased risk for tuberculosis, heart disease, lung cancer, and connective tissue disease.

  1. Tuberculosis - a bacterial infection that causes the formation of tubercles (lesions) in the lungs. Experts do not know why silicosis sufferers are at an increased risk for tuberculosis, but they theorize that silicosis depresses the immune system, increasing the risk of bacterial infection.
  2. Heart disease - the formation of scar tissue in the lungs requires the heart to work harder to move blood throughout the body. As a result, it increases the risk of heart failure.
  3. Lung cancer - for unknown reasons, silicosis sufferers are at an increased risk for lung cancer.
  4. Connective tissue disease - a group of diseases that include rheumatoid arthritis, lupus, rheumatic fever, and systemic sclerosis. Evidence suggests that these diseases may originate from an autoimmune response.
  5. Chronic bronchitis - associated with airflow obstruction and a chronic cough. This disease is common among workers who are exposed to silica.
  6. Silicoproteinosis - a fatal lung disease characterized by the decreased ability of the lungs to produce oxygen

Silica Exposure
Silica exposure occurs when dust that contains crystalline silica particles is inhaled. It is estimated that approximately 1,200,000 workers are exposed to silica each year. Silica, or silicon dioxide, is a naturally occurring mineral that is composed of one silicon atom and two oxygen atoms. When silica molecules line up and create a repeating pattern they form a crystal (crystalline silica). Different crystal patterns are given different names; the most common is quartz. Silica is a major component of sand and granite.

Materials that contain crystalline silica

The following is a list of construction materials that contain crystalline silica:

  • Blasting abrasives
  • Foundry Operations
  • Brick
  • Concrete
  • Cement mortar
  • Granite
  • Sandstone
  • Slate
  • Mineral deposits
  • Rock and stone
  • Sand
  • Topsoil
  • Asphalt

Occupations at high risk of silica exposure

Occupations that put workers at an increased risk of silica exposure include:

  • Construction
  • Demolition Mining
  • Sandblasting
  • Stone masonry
  • Abrasives manufacturing
  • Glass manufacturing
  • Pottery
  • Railroad track setting, laying, and repair
  • Painting
  • Plumbing

The Occupational Safety and Health Administration (OSHA) requires employers to limit workers' exposure to crystalline silica by all available means, including water sprays, blasting cabinets, and ventilation systems.

For more information, visit:
http://www.osha.gov