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.
(See also Overview of Environmental and Occupational Lung Disease Overview of Environmental and Occupational Lung Disease Environmental and occupational lung diseases result from inhalation of dusts, chemicals, gases, fumes, and other airborne exposures. The lungs are continually exposed to the external environment... read more .)
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).
Symptoms of Silicosis
Silicosis can be acute or chronic. Chronic silicosis is more common.
People with acute silicosis experience shortness of breath, weight loss, and fatigue that progresses quickly. Respiratory failure Respiratory Failure Respiratory failure is a condition in which the level of oxygen in the blood becomes dangerously low or the level of carbon dioxide in the blood becomes dangerously high. Conditions that block... read more is 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.
People with silicosis are at risk of other disorders:
Chronic obstructive pulmonary disease (COPD)
Systemic rheumatic (autoimmune) diseases
People with silicosis have an increased risk of developing mycobacterial infections, such as tuberculosis Tuberculosis (TB) Tuberculosis is a chronic contagious infection caused by the airborne bacteria Mycobacterium tuberculosis. It usually affects the lungs, but almost any organ can be involved. Tuberculosis... read more .
Silica exposure is associated with increased risk of chronic obstructive pulmonary disease Chronic Obstructive Pulmonary Disease (COPD) Chronic obstructive pulmonary disease is persistent narrowing (blocking, or obstruction) of the airways occurring with emphysema, chronic obstructive bronchitis, or both disorders. Cigarette... read more (such as emphysema or chronic bronchitis).
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 . Crystalline silica has been identified by the International Agency for Research on Cancer (IARC) as a Group 1 human lung carcinogen.
Exposure to crystalline silica is also associated with increased risk of several systemic rheumatic diseases, including rheumatoid arthritis Rheumatoid Arthritis (RA) Rheumatoid arthritis is an inflammatory arthritis in which joints, usually including those of the hands and feet, are inflamed, resulting in swelling, pain, and often destruction of joints.... read more and systemic sclerosis Systemic Sclerosis Systemic sclerosis is a rare, chronic autoimmune connective tissue disorder characterized by degenerative changes and scarring in the skin, joints, and internal organs and by blood vessel abnormalities... read more .
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 , 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.
People who have difficulty breathing may benefit from use of bronchodilators, which are medications to keep the airways open and free of mucus. Doctors monitor people with silicosis for low oxygen levels in the blood and treat them if needed. Pulmonary rehabilitation Pulmonary Rehabilitation Pulmonary rehabilitation is the use of supervised exercise, education, support, and behavioral intervention to improve how people with chronic lung disease function in daily life and to enhance... read more may help people carry out activities of daily living. Lung transplantation Lung and Heart-Lung Transplantation Lung transplantation is the surgical removal of a healthy lung or part of a lung from a living person and then its transfer into someone whose lungs no longer function. Heart-lung transplantation... read more is recommended for those most severely affected.
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.
Measures to prevent complications include smoking cessation Smoking Cessation Most people who smoke want to quit and have tried doing so with limited success. Effective tools to help quit smoking include counseling, nicotine replacement products, and medications. While... read more and vaccinations against pneumococci Pneumococcal Vaccine Pneumococcal vaccines help protect against bacterial infections caused by Streptococcus pneumoniae (pneumococci). Pneumococcal infections include ear infections, sinusitis, pneumonia... read more , COVID COVID-19 Vaccine Coronavirus disease 2019 (COVID-19) vaccines provide protection against COVID-19. COVID-19 is the disease caused by infection with the SARS-CoV-2 virus. There are multiple COVID-19 vaccines... read more , and influenza Influenza Vaccine The influenza virus vaccine helps protect against influenza. Two types of influenza virus, type A and type B, regularly cause seasonal epidemics of influenza in the United States. There are... read more . Because people who have been exposed to silica are at risk of tuberculosis Tuberculosis (TB) Tuberculosis is a chronic contagious infection caused by the airborne bacteria Mycobacterium tuberculosis. It usually affects the lungs, but almost any organ can be involved. Tuberculosis... read more and similar mycobacterial infections, they should have regular tuberculosis screening.
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.
The following English-language resource may be useful. Please note that THE MANUAL is not responsible for the content of this resource.
Occupational Safety & Health Administration [OSHA]. Respirable crystalline silica. 2016. Regulations (Standards-29 CFR 1926.1153.