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Silicosis

By

Carrie A. Redlich

, MD, MPH, Yale Occupational and Environmental Medicine Program Yale School of Medicine;


Efia S. James

, MD, MPH, Yale School of Medicine;


Brian Linde

, MD, MPH, Yale Occ and Env Medicine Program

Reviewed/Revised Nov 2023
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Topic Resources

Silicosis is permanent scarring of the lungs caused by inhaling silica (quartz) dust.

  • People develop difficulty breathing during activity that sometimes progresses to shortness of breath at rest.

  • Some people also have a cough that may or may not produce sputum.

  • Diagnosis is based on a chest x-ray or chest computed tomography scan and a history of silica exposure.

  • Doctors may give medications to help breathing.

Silicosis may be acute or chronic. Acute silicosis may develop after intense exposures over a few weeks or years. Chronic silicosis is the most common form and generally develops only after exposure over decades.

Causes of Silicosis

Silica is one of the most abundant minerals in the earth's crust and is widely distributed in nature. Silicosis is caused by inhalation of tiny particles of crystalline silica (usually quartz). Workers at greatest risk are those who move or blast rock and sand (miners, quarry workers, stonecutters, construction workers) or who use silica-containing rock or sand abrasives (sand blasters, glass makers, foundry, gemstone, and ceramic workers, potters). Outbreaks of severe silicosis have recently been identified in workers in the engineered stone industry.

Factors that influence the incidence and severity of silicosis include

  • Duration and intensity of exposure

  • Form and surface characteristics of the silica particles

Amorphous silica, such as glass or diatomaceous earth, does not have a crystalline structure and does not cause silicosis.

When inhaled, silica dust passes into the lungs, and scavenger cells such as macrophages engulf it (see Overview of the Immune System Overview of the Immune System The immune system is designed to defend the body against foreign or dangerous invaders. Such invaders include Microorganisms (commonly called germs, such as bacteria, viruses, and fungi) Parasites... read more ). Enzymes released by the scavenger cells cause the lung tissue to scar and form nodules. In low-intensity or short-term exposures, these nodules remain discrete and do not compromise lung function. With higher-intensity or more prolonged exposures, these nodules coalesce (come together) and cause progressive fibrosis and lung dysfunction, or they sometimes form large masses (called progressive massive fibrosis).

Silicosis
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Symptoms of Silicosis

Silicosis can be acute or chronic. Chronic silicosis is more common.

Chronic silicosis often does not cause symptoms for years, but can progress to more severe disease. Many people with chronic silicosis develop difficulty breathing and cough over time. The lung damage can lead to lower levels of oxygen in the blood and can also strain the right side of the heart. This strain can lead to a type of heart failure called cor pulmonale Pulmonary Hypertension Pulmonary hypertension is a condition in which blood pressure in the arteries of the lungs (the pulmonary arteries) is abnormally high. Many disorders can cause pulmonary hypertension. People... read more , which can be fatal.

Complications

People with silicosis are at risk of other disorders:

  • Tuberculosis (TB)

  • Chronic obstructive pulmonary disease (COPD)

  • Lung cancer

  • Systemic rheumatic (autoimmune) diseases

People with silicosis are at increased risk of lung cancer Lung Cancer Lung cancer is the leading cause of cancer death in both men and women. About 85% of cases are related to cigarette smoking. One common symptom is a persistent cough or a change in the character... read more Lung Cancer . Crystalline silica has been identified by the International Agency for Research on Cancer (IARC) as a Group 1 human lung carcinogen.

Diagnosis of Silicosis

  • History of silica exposure

  • Chest imaging (computed tomography or x-ray)

Doctors usually recognize silicosis based on what they see on chest x-ray or computed tomography (CT) in people with a history of silica exposure. Chest CT is more sensitive than chest x-ray for detecting silicosis and monitoring for disease progression.

On chest imaging, a number of disorders can resemble chronic silicosis. They include sarcoidosis Sarcoidosis Sarcoidosis is a disease in which abnormal collections of inflammatory cells (granulomas) form in many organs of the body. Sarcoidosis usually develops in people aged 20 to 40 years, most often... read more Sarcoidosis , chronic beryllium disease Beryllium Disease Chronic beryllium disease is lung inflammation caused by inhaling dust or fumes that contain beryllium, a metal that is used in small amounts in many industries. People with chronic beryllium... read more , hypersensitivity pneumonitis Hypersensitivity Pneumonitis Hypersensitivity pneumonitis is a type of inflammation in and around the tiny air sacs (alveoli) and smallest airways (bronchioles) of the lung caused by a hypersensitivity reaction to inhaled... read more , coal worker pneumoconiosis Coal Worker Pneumoconiosis Coal worker pneumoconiosis is a lung disease caused by deposits of coal mining dust in the lungs. Symptoms include cough and shortness of breath which can progress over time. Chest x-rays and... read more , miliary tuberculosis Miliary Tuberculosis (TB) Miliary tuberculosis is a potentially life-threatening type of tuberculosis that occurs when a large number of the bacteria travel through the bloodstream and spread throughout the body. Tuberculosis... read more , fungal pulmonary diseases, and cancer that has spread to the lungs. Doctors do additional tests to distinguish silicosis from these other disorders.

Treatment of Silicosis

  • Removal from further exposure

  • Management of symptoms (for example, with bronchodilators and inhaled corticosteroids)

  • Management of complications

Removal from further exposure is important.

There are no proven, specific treatments for acute or chronic silicosis. Treatment is primarily supportive.

Complications are managed as needed. For example, infections, including tuberculosis, are treated promptly.

Prevention of Silicosis

Primary preventive measures begin with eliminating or reducing exposure. The most effective primary prevention is implementation of engineering controls (control of the environment) to limit exposure to silica. Properly fitted respirators provide additional protection.

Due to persistence of silicosis, the United States Occupational Safety and Health Administration (OSHA) issued an updated Respirable Silica Standard in 2016. The standard lowers the Permissible Exposure Limit (PEL) and requires pre-employment and periodic medical surveillance of silica-exposed workers. Medical surveillance includes questionnaires, lung function tests, and periodic chest x-rays.

More Information

The following English-language resource may be useful. Please note that THE MANUAL is not responsible for the content of this resource.

NOTE: This is the Consumer Version. DOCTORS: VIEW PROFESSIONAL VERSION
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