Asbestosis
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Asbestosis is long-term
inflammation Inflammation (from ) is part of the biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. The five cardinal signs are heat, pain, redness, swelling, and loss of function (Latin ''calor'', '' ...
and
scarring A scar (or scar tissue) is an area of fibrous tissue that replaces normal skin after an injury. Scars result from the biological process of wound repair in the skin, as well as in other organs, and tissues of the body. Thus, scarring is a nat ...
of the
lungs The lungs are the primary organs of the respiratory system in many animals, including humans. In mammals and most other tetrapods, two lungs are located near the backbone on either side of the heart. Their function in the respiratory syste ...
due to
asbestos Asbestos ( ) is a group of naturally occurring, Toxicity, toxic, carcinogenic and fibrous silicate minerals. There are six types, all of which are composed of long and thin fibrous Crystal habit, crystals, each fibre (particulate with length su ...
fibers. Symptoms may include
shortness of breath Shortness of breath (SOB), known as dyspnea (in AmE) or dyspnoea (in BrE), is an uncomfortable feeling of not being able to breathe well enough. The American Thoracic Society defines it as "a subjective experience of breathing discomfort that con ...
, cough, wheezing, and chest tightness. Complications may include
lung cancer Lung cancer, also known as lung carcinoma, is a malignant tumor that begins in the lung. Lung cancer is caused by genetic damage to the DNA of cells in the airways, often caused by cigarette smoking or inhaling damaging chemicals. Damaged ...
,
mesothelioma Mesothelioma is a type of cancer that develops from the thin layer of tissue that covers many of the internal organs (known as the mesothelium). The area most commonly affected is the lining of the lungs and chest wall. Less commonly the lini ...
, and pulmonary heart disease. Asbestosis is caused by breathing in asbestos fibers. It requires a relatively large exposure over a long period of time, which typically only occurs in those who directly work with asbestos. All types of asbestos fibers are associated with an increased risk. It is generally recommended that currently existing and undamaged asbestos be left undisturbed. Diagnosis is based upon a history of exposure together with
medical imaging Medical imaging is the technique and process of imaging the interior of a body for clinical analysis and medical intervention, as well as visual representation of the function of some organs or tissues (physiology). Medical imaging seeks to revea ...
. Asbestosis is a type of interstitial pulmonary fibrosis. There is no specific treatment. Recommendations may include
influenza vaccination Influenza vaccines, colloquially known as flu shots or the flu jab, are vaccines that protect against infection by influenza viruses. New versions of the vaccines are developed twice a year, as the influenza virus rapidly changes. While thei ...
, pneumococcal vaccination,
oxygen therapy Oxygen therapy, also referred to as supplemental oxygen, is the use of oxygen as medical treatment. Supplemental oxygen can also refer to the use of oxygen enriched air at altitude. Acute indications for therapy include hypoxemia (low blood o ...
, and stopping
smoking Smoking is a practice in which a substance is combusted, and the resulting smoke is typically inhaled to be tasted and absorbed into the bloodstream of a person. Most commonly, the substance used is the dried leaves of the tobacco plant, whi ...
. Asbestosis affected about 157,000 people and resulted in 3,600 deaths in 2015. Asbestos use has been banned in a number of countries in an effort to prevent disease. Statistics from the UK's
Health and Safety Executive The Health and Safety Executive (HSE) is a British public body responsible for the encouragement, regulation and enforcement of workplace health, safety and welfare. It has additionally adopted a research role into occupational risks in Great B ...
showed that in 2019, there were 490 asbestosis deaths.


Signs and symptoms

The signs and symptoms of asbestosis typically manifest after a significant amount of time has passed following asbestos exposure, often several decades under current conditions in the US. The primary symptom of asbestosis is generally the slow onset of
shortness of breath Shortness of breath (SOB), known as dyspnea (in AmE) or dyspnoea (in BrE), is an uncomfortable feeling of not being able to breathe well enough. The American Thoracic Society defines it as "a subjective experience of breathing discomfort that con ...
, especially with physical activity. Clinically advanced cases of asbestosis may lead to
respiratory failure Respiratory failure results from inadequate gas exchange by the respiratory system, meaning that the arterial oxygen, carbon dioxide, or both cannot be kept at normal levels. A drop in the oxygen carried in the blood is known as hypoxemia; a r ...
. When a
stethoscope The stethoscope is a medicine, medical device for auscultation, or listening to internal sounds of an animal or human body. It typically has a small disc-shaped resonator that is placed against the skin, with either one or two tubes connected t ...
is used to listen to the lungs of a person with asbestosis, they may hear inspiratory "crackles". The characteristic pulmonary function finding in asbestosis is a restrictive ventilatory defect. This manifests as a reduction in lung volumes, particularly the
vital capacity Vital capacity (VC) is the maximum amount of air a person can expel from the lungs after a maximum inhalation. It is equal to the sum of inspiratory reserve volume, tidal volume, and expiratory reserve volume. It is approximately equal to Force ...
(VC) and total lung capacity (TLC). The TLC may be reduced through alveolar wall thickening; however, this is not always the case. Large airway function, as reflected by FEV1/FVC, is generally well preserved. In severe cases, the drastic reduction in lung function due to the stiffening of the lungs and reduced TLC may induce right-sided heart failure ( cor pulmonale). In addition to a restrictive defect, asbestosis may produce reduction in diffusion capacity and a low amount of oxygen in the blood of the arteries.


Cause

The cause of asbestosis is the
inhalation Inhalation (or inspiration) happens when air or other gases enter the lungs. Inhalation of air Inhalation of air, as part of the cycle of breathing, is a vital process for all human life. The process is autonomic (though there are exceptions ...
of microscopic
asbestos Asbestos ( ) is a group of naturally occurring, Toxicity, toxic, carcinogenic and fibrous silicate minerals. There are six types, all of which are composed of long and thin fibrous Crystal habit, crystals, each fibre (particulate with length su ...
mineral fibers suspended in the air. In the 1930s, E. R. A. Merewether found that greater exposure resulted in greater risk.


Risk factors

Those who worked in the production, milling, manufacturing, installation, or removal of asbestos products before the late 1970s are at an increased risk of exposure to asbestos. This includes people who worked in these jobs in the United States and Canada. For example: * Asbestos miners * Aeronautical and car mechanics * Boiler operators * Construction workers * Electricians * Railway workers * Workers who remove asbestos insulation from around a steam vessel in an old building Construction workers who inhale asbestos from contaminated building materials such as paint, spackling, roof shingles, masonry compounds, and drywall may get asbestosis. The amount and length of an individual's exposure to asbestos are the primary factors that determine the level of risk. The longer one is exposed to the substance, the higher their risk of developing lung damage. Families of exposed workers can be affected because asbestos fibers from clothing and hair can end up in the home. People who live near mines can also be exposed to airborne asbestos fibers.


Pathogenesis

Asbestosis is the scarring of lung tissue (beginning around terminal
bronchiole The bronchioles ( ) are the smaller branches of the bronchial airways in the lower respiratory tract. They include the terminal bronchioles, and finally the respiratory bronchioles that mark the start of the respiratory zone delivering air to ...
s and alveolar ducts and extending into the alveolar walls) resulting from the inhalation of
asbestos Asbestos ( ) is a group of naturally occurring, Toxicity, toxic, carcinogenic and fibrous silicate minerals. There are six types, all of which are composed of long and thin fibrous Crystal habit, crystals, each fibre (particulate with length su ...
fibers. There are two types of fibers: amphibole (thin and straight) and serpentine (curly). All forms of asbestos fibers are responsible for human disease as they are able to penetrate deeply into the lungs. When such fibers reach the alveoli (air sacs) in the lung, where oxygen is transferred into the blood, the foreign bodies (asbestos fibers) cause the activation of the lungs' local
immune system The immune system is a network of biological systems that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to bacteria, as well as Tumor immunology, cancer cells, Parasitic worm, parasitic ...
and provoke an inflammatory reaction dominated by lung macrophages that respond to chemotactic factors activated by the fibers. This inflammatory reaction can be described as chronic rather than acute, with a slow ongoing progression of the immune system attempting to eliminate the foreign fibers.
Macrophage Macrophages (; abbreviated MPhi, φ, MΦ or MP) are a type of white blood cell of the innate immune system that engulf and digest pathogens, such as cancer cells, microbes, cellular debris and foreign substances, which do not have proteins that ...
s phagocytose (ingest) the fibers and stimulate
fibroblast A fibroblast is a type of cell (biology), biological cell typically with a spindle shape that synthesizes the extracellular matrix and collagen, produces the structural framework (Stroma (tissue), stroma) for animal Tissue (biology), tissues, and ...
s to deposit connective tissue. Due to the asbestos fibers' natural resistance to digestion, some macrophages release inflammatory chemical signals, and other macrophages are killed, releasing reactive oxygen species and activating transcription factors, like NF-kB, which amplify the expression of pro-inflammatory cytokines. These inflammatory chemical signals attract further lung macrophages and fibrolastic cells that synthesize fibrous scar tissue, which eventually becomes diffuse and can progress in heavily exposed individuals. This tissue can be seen microscopically soon after exposure in animal models. Some asbestos fibers become layered by an iron-containing proteinaceous material ( ferruginous body) in cases of heavy exposure where about 10% of the fibers become coated. Most inhaled asbestos fibers remain uncoated. About 20% of the inhaled fibers are transported by cytoskeletal components of the alveolar epithelium to the interstitial compartment of the lung where they interact with macrophages and mesenchymal cells. The cytokines, transforming growth factor beta and tumor necrosis factor alpha, appear to play major roles in the development of scarring inasmuch as the process can be blocked in animal models by preventing the expression of the growth factors. The result is fibrosis in the interstitial space, thus asbestosis. This fibrotic scarring causes alveolar walls to thicken, which reduces elasticity and gas diffusion, reducing oxygen transfer to the blood as well as the removal of
carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...
. This can result in shortness of breath, a common symptom exhibited by individuals with asbestosis. Those with asbestosis may be more vulnerable to tumor growth (mesothelioma), because asbestos decreases the cytotoxicity of natural killer cells and impairs the functioning of T helper cells, which detect abnormal cell growth.


Diagnosis

According to the American Thoracic Society (ATS), the general diagnostic criteria for asbestosis are: * Evidence of structural pathology consistent with asbestosis, as documented by imaging or histology * Evidence of causation by asbestos as documented by the occupational and environmental history, markers of exposure (usually pleural plaques), recovery of asbestos bodies, or other means * Exclusion of alternative plausible causes for the findings The abnormal chest x-ray and its interpretation remain the most important factors in establishing the presence of pulmonary fibrosis. The findings usually appear as small, irregular parenchymal opacities, primarily in the lung bases. Using the ILO Classification system, "s", "t", and/or "u" opacities predominate. CT or high-resolution CT (HRCT) are more sensitive than plain radiography at detecting pulmonary fibrosis (as well as any underlying pleural changes). More than 50% of people affected with asbestosis develop plaques in the parietal pleura, the space between the chest wall and lungs. Once apparent, the radiographic findings in asbestosis may slowly progress or remain static, even in the absence of further asbestos exposure. Rapid progression suggests an alternative diagnosis. Asbestosis resembles many other diffuse interstitial lung diseases, including other pneumoconiosis. The differential diagnosis includes idiopathic pulmonary fibrosis (IPF),
hypersensitivity pneumonitis Hypersensitivity pneumonitis (HP) or extrinsic allergic alveolitis (EAA) is a syndrome caused by the repetitive inhalation of antigens from the environment in susceptible or sensitized people. Common antigens include molds, bacteria, bird droppin ...
,
sarcoidosis Sarcoidosis (; also known as Besnier–Boeck–Schaumann disease) is a disease involving abnormal collections of White blood cell, inflammatory cells that form lumps known as granulomata. The disease usually begins in the lungs, skin, or lymph n ...
, and others. The presence of pleural plaques may provide supportive evidence of causation by asbestos. Although lung biopsy is usually not necessary, the presence of asbestos bodies in association with pulmonary fibrosis establishes the diagnosis. Conversely, interstitial pulmonary fibrosis in the absence of asbestos bodies is most likely not asbestosis. Asbestos bodies in the absence of fibrosis indicate exposure, not disease. Image:Asbestos effect.jpg, Figure A shows the location of the lungs, airways, pleura, and diaphragm in the body. Figure B shows lungs with asbestos-related diseases, including pleural plaque, lung cancer, asbestosis, plaque on the diaphragm, and mesothelioma. Image:Asbestosis (7468458838).jpg, Extensive fibrosis of pleura and lung parenchyma Image:Asbestosis - Asbestos body (7468457368).jpg, The arrow points to an uncoated segment of asbestos fiber in this ferruginous body. Image:Asbestosis - Pleural fibrosis & calcification (7468458058).jpg, Severe pleural fibrosis with focal calcification Image:Asbestosis and non-small cell lung carcinoma, NOS (7469998482).jpg, The black arrows point to ferrugionous bodies that are located at the periphery of a focus of non-small cell lung carcinoma, NOS. File:Asbestosis_2.jpg, 61-year-old working industrially with asbestos for decades


Treatment

There is no cure available for asbestosis.
Oxygen therapy Oxygen therapy, also referred to as supplemental oxygen, is the use of oxygen as medical treatment. Supplemental oxygen can also refer to the use of oxygen enriched air at altitude. Acute indications for therapy include hypoxemia (low blood o ...
at home is often necessary to relieve the shortness of breath and correct underlying low blood oxygen levels. Supportive treatment of symptoms includes respiratory
physiotherapy Physical therapy (PT), also known as physiotherapy, is a healthcare profession, as well as the care provided by physical therapists who promote, maintain, or restore health through patient education, physical intervention, disease preventio ...
to remove secretions from the lungs by postural drainage, chest percussion, and vibration. Nebulized medications may be prescribed in order to loosen secretions or treat underlying
chronic obstructive pulmonary disease Chronic obstructive pulmonary disease (COPD) is a type of progressive lung disease characterized by chronic respiratory symptoms and airflow limitation. GOLD defines COPD as a heterogeneous lung condition characterized by chronic respiratory s ...
. Immunization against pneumococcal pneumonia and annual
influenza Influenza, commonly known as the flu, is an infectious disease caused by influenza viruses. Symptoms range from mild to severe and often include fever, runny nose, sore throat, muscle pain, headache, coughing, and fatigue. These sympto ...
vaccination is administered due to increased sensitivity to the diseases. Those with asbestosis are at increased risk for certain cancers. If the person smokes, quitting the habit reduces further damage. Periodic pulmonary function tests, chest x-rays, and clinical evaluations, including cancer screening/evaluations, are given to detect additional hazards.


Society and culture


Legal issues

On 21 December 1906 H. Montague Murray, M.D., F.R.C.P., testified before a British committee concerning a patient who died in April 1900. Murray indicated that fibrosis of the lungs caused by asbestos dust was a plausible cause of the patient's death. The death of English textile worker Nellie Kershaw in 1924 from pulmonary asbestosis was the first case to be described in medical literature, and the first published account of disease definitely attributed to occupational asbestos exposure. However, her former employers (Turner Brothers Asbestos) denied that asbestosis even existed because the medical condition was not officially recognised at the time. As a result, they accepted no liability for her injuries and paid no compensation, either to Kershaw during her final illness or to her family after her death. Even so, the findings of the
inquest An inquest is a judicial inquiry in common law jurisdictions, particularly one held to determine the cause of a person's death. Conducted by a judge, jury, or government official, an inquest may or may not require an autopsy carried out by a cor ...
into her death were highly influential insofar as they led to a parliamentary enquiry by the
British Parliament The Parliament of the United Kingdom of Great Britain and Northern Ireland is the supreme legislative body of the United Kingdom, and may also legislate for the Crown Dependencies and the British Overseas Territories. It meets at the Palace of ...
. The enquiry formally acknowledged the existence of asbestosis, recognised that it was hazardous to health and concluded that it was irrefutably linked to the prolonged inhalation of asbestos dust. Having established the existence of asbestosis on a medical and judicial basis, the report resulted in the first Asbestos Industry Regulations being published in 1931, which came into effect on 1 March 1932. The first lawsuits against asbestos manufacturers occurred in 1929. Since then, many lawsuits have been filed against asbestos manufacturers and employers, for neglecting to implement safety measures after the link between asbestos, asbestosis and mesothelioma became known (some reports seem to place this as early as 1898 in modern times). The liability resulting from the sheer number of lawsuits and people affected has reached billions of U.S. dollars. The amounts and method of allocating compensation have been the source of many court cases, and government attempts at resolution of existing and future cases. To date, about 100 companies have declared bankruptcy at least partially due to asbestos-related liability. In accordance with Chapter 11 and § 524(g) of the U.S. federal bankruptcy code, a company may transfer its liabilities and certain assets to an asbestos personal injury trust, which is then responsible for compensating present and future claimants. Since 1988, 60 trusts have been established to pay claims with about $37 billion in total assets. From 1988 through 2010, analysis from the United States Government Accountability Office indicates that trusts have paid about 3.3 million claims valued at about $17.5 billion.


Notable people

This is a partial list of notable people who have died from lung fibrosis associated with asbestos: * Bernie Banton, social justice advocate * Paul Gleason, ''Breakfast Club'' actor * Nellie Kershaw, first person diagnosed with asbestos-related disease, 1924 * John MacDougall, politician *
Steve McQueen Terrence Stephen McQueen (March 24, 1930November 7, 1980) was an American actor. His antihero persona, emphasized during the height of counterculture of the 1960s, 1960s counterculture, made him a top box office draw for his films of the late ...
, actor *
Theodore Sturgeon Theodore Sturgeon (; born Edward Hamilton Waldo, February 26, 1918 – May 8, 1985) was an American author of primarily fantasy fiction, fantasy, science fiction, and Horror fiction, horror, as well as a critic. He wrote approximately 400 ...
, writer


References


External links

* * * * * {{Authority control Asbestos Lung diseases due to external agents Lung disorders Occupational diseases Pollution Wikipedia medicine articles ready to translate