Silicosis is the chronic fibrosing disease of the lungs produced by the prolonged and extensive exposure to free crystalline silica dust. When workers inhale crystalline silica (dust), the lung tissue reacts by developing fibrotic nodules and scarring around the trapped silica particles. This fibrotic condition of the lung is called silicosis. If the nodules grow too large, breathing becomes difficult and death may result. Silicosis victims are also at high risk of developing active tuberculosis. More than one million U.S. workers are exposed to crystalline silica, and each year hundreds of these workers die from silicosis. Silicosis treatment is very limited as there is no cure for the disease, but it is 100 percent preventable if employers, workers, and health professionals work together to reduce exposures.
Pneumoconiosis is the general term for lung disease caused by inhalation of mineral dust. Silicosis is a fibrosing lung disease caused by inhalation of dust containing crystalline silica (alpha-quartz or silicon dioxide), which is distributed widely, or its polymorphs (tridymite or cristobalite), which are distributed less widely. Silica-related diseases are associated only with crystalline-free silica. The most common examples of crystalline-free silica are beach or bank sands. A third form of free silica is fused silica which is produced by heating either the amorphous or crystalline forms. Other forms include cristobalite and tridymite. Workers exposed to silica dust are often exposed to asbestos as well and many will develop asbestos lung diseases including a rare lung disease called mesothelioma.
Types of Silicosis:
Workers may develop any of three types of silicosis, depending on the concentration of airborne silica:
- Chronic silicosis, which usually occurs after ten or more years of exposure to crystalline silica at relatively low concentrations.
- Accelerated silicosis which results from exposure to high concentrations of crystalline silica and develops five to ten years after the initial exposure.
- Acute silicosis, which occurs where exposure concentrations are the highest and can cause symptoms to develop within a few weeks to four or five years after the initial exposure.
Silicosis Symptoms and Side Effects of Silicosis Lung Disease:
Early stages of silicosis may go unnoticed. Continued exposure to silica dust may result in a shortness of breath on exercising, possible fever and occasionally bluish skin at the ear lobes or lips. Silicosis makes a person more susceptible to infectious diseases of the lungs, such as tuberculosis. Progression of silicosis leads to fatigue, extreme shortness of breath, loss of appetite, pains in the chest, and respiratory failure, which may cause death.
Medical evaluations of silicosis victims usually show the lungs to be filled with silica crystals and a protein material. Pulmonary fibrosis (fibrous tissue in the lung) may or may not develop in acute cases of silicosis depending on the time between the exposure and the onset of symptoms. Furthermore, evidence indicates that crystalline silica is a potential occupational carcinogen.
At-Risk Occupations for Silica Dust Exposure:
It is generally recognized that people working in the following industries have the greatest risk of being exposed to silica dust and contracting silicosis:
- Mining – Tunneling
- Stone Crushing
- Rock Quarries Work- Rock Drilling
- Masonry – Cement Work
- Foundry Workers, Sand Mold Shakeout
- Sandblast Dust Exposure to other Non-Sandblasters in work area
- Cutting or manufacturing heat-resistant bricks (Fire Brick)
- Manufacturing of glass products
- Railroad construction