Asbestosis (Asbestoses)

Asbestosis - Fibrous pleural plaque (7468458430)[1]

Asbestosis is a pneumoconiosis caused by inhaled asbestos fibers. It is marked by pulmonary fibrosis.[1]

The disease is related to the following process: Poison.

Presentation

The presentation of patients after asbestos exposure is not immediate. The symptoms often do not appear for several decades after exposure. This latency may be shortened if the intensity of exposure to asbestosis is high [7][8].
The most common presenting feature of asbestosis is dyspnea on exertion, which once started is progressive in nature. Other may also complain of a dry non-productive cough. Presence of a productive cough indicates a concomitant respiratory tract infection. Vague chest pain or discomfort is also a common complaint in patients with advanced disease.
Physical exam may reveal rales which are primarily heard at the lung bases and in the lower posterior area beneath the scapula.
Clubbing of the digits may be seen in 50% of patients but has no correlation to the severity of the disease.
With advanced disease, there will be decreased expansion of the chest that clinically correlates with restrictive ventilatory impairment and reduced vital capacity. Patients with Cor pulmonale may have varying degrees of cyanosis, hepatojugular reflux, jugular venous distension and pedal edema. Most patients with end stage lung disease appear cachectic, out of breath and moribund.

Workup

The diagnosis of asbestosis is based on the following:

  • One must obtain a thorough history and take into account the dose and duration of exposure to asbestos. It is important to known the type of work one was performing and if any body protection was used (garments, gloves or masks).
  • Always ask for an old chest x-ray to determine if the disease was present earlier and it has progressed, as compared to the present chest x-ray.
  • Determine degree of dyspnea - whether it is at rest, exercise or during sleep
  • Any prior treatment for heart failure as some patients may have developed right heart failure
  • Laboratory blood tests are not specific for diagnosis of asbestosis exposure but a blood gas is needed to determine hypoxia and hypercarbia.
  • Gallium citrate scan is not recommended as it is not specific for asbestosis.
  • Even though some healthcare workers make the diagnosis of asbestosis based on the history and physical, errors in diagnosis can occur because there are many other interstitial lung diseases that can present with similar features of asbestosis. When using the history to make the diagnosis, it is important to keep in mind that there is a long latent period between exposure and development of symptoms. Many cases of medical malpractice have resulted when the diagnosis of asbestosis is missed because of reliance on just the history and physical exam.

Radiography

  • Chest x-ray will show diffuse reticulonodular infiltrates in the middle and lower lung segments. Honeycombing may be seen in advanced disease. Typically there will be thickening of the lower and middle pleural wall. Sometimes a large calcified pleural plaque on the diaphragmatic pleura may be seen.
  • CT scan is always done in a patient with asbestosis. The Ct scan can determine the size and location of any pleural lesion, presence of effusion, invasion of the chest wall or other structures, or atelectasis. CT scan is also excellent at defining the fibrosis. Even in people with normal chest xrays, the CT scan will reveal presence of abnormalities

Pulmonary Function Test
Pulmonary function tests are performed in patients with asbestosis but are not specific. The CO diffusing capacity is decreased and may be the earliest abnormality seen. As the disease advances, the patient will develop reduction in total lung capacity and vital capacity. However, these features are nonspecific and can be seen in many other restrictive lung disorders.


Oximetry
Pulse oximetry will usually reveal hypoxia which may be exacerbated in the presence of right heart failure and cor pulmonale. In the clinic, the pulse oximetry can be performed at rest and during exercise and can quickly reveal the severity of hypoxemia


Bronchoalveolar Lavage and Bronchoscopy
The role of bronchoscopy and bronchoalveolar lavage in making the diagnosis of asbestosis is limited. It is only helpful when trying to make a diagnosis of an infection or determining the cause of a sudden wheeze in an elderly individual. During bronchoscopy, the airways can be lavaged and the fluid is collected to assess the number of asbestos fibers. If there is more than one asbestos body/ml of lavage from the airways, then the probability of high exposure to asbestos is likely. Bronchoscopy should not be used to perform a lung biopsy as the tissue yield is inadequate and false negatives are high.

Lung biopsy
Lung biopsy is necessary to make the diagnosis of asbestosis and rule out other disorders. In addition, the lung biopsy may reveal the absence or presence of a malignancy. The biopsy specimen is usually viewed under light and electron microscopy and reveal presence of fibrosis and asbestosis bodies. A grading system has been developed to assess the severity of asbestosis related fibrosis. It is important to note that presence of asbestosis bodies alone is not diagnostic for the disorder because sometimes the pathologist may observe these bodies in individuals who have had no exposure or have had only a transient exposure to asbestos


Biopsy of the pleura
Pleural thickening can occur with asbestosis and it is difficult to know if this is a benign or malignant lesion. Hence a biopsy is required. This is usually done in the operating room via an open procedure because the yield from a needle biopsy is not sufficient to make the diagnosis of a malignancy. Even though pleural plaques can occur with several other medical disorders, the presence of plaques and dyspnea should be a good indicator of prior exposure to asbestos.

Treatment

  • Once the diagnosis of asbestosis has been made, the goal of the treatment is to prevent any further exposure and manage the symptoms. The patient should be strongly advised to discontinue smoking [9].
  • The severity of the lung disease and functional impairment should be studied and treatment individualized. Then a follow up plan must be developed to monitor the patient. This may involve regular pulmonary function tests, arterial blood gases, and obtain serial chest x-ray or CT scans. The patient’s oxygen status must be assessed at rest and with exercise to determine if hypoxemia occurs at rest or with exercise.
  • Supplemental oxygen may be required while ambulation or at night time.
  • If the patient has an upper respiratory tract infection or pneumonia, appropriate antibiotic treatment is needed.
  • All patients with asbestosis should be immunized against pneumococcal pneumonia and influenza.
  • Many patients with end stage lung disease are cachectic, immobile and bedridden. These patients may require appropriate palliative care. Relief from shortness of breath must be provided. During the terminal phase of the disease, comfort and supportive care is needed.
  • Once asbestosis has developed, there is no effective medication. Even though both corticosteroids and a variety of immunosuppressive agents have been tried, the course of the disorder is not altered.
  • For patients who develop wheezing, bronchodilators are useful.
  • Patients who have developed lung cancer or a mesothelioma need to be referred to a thoracic surgeon. Most patients are either not candidates for surgery or the cancer is too far advanced

Prognosis

The prognosis for most individuals after prolonged exposure to asbestos has to be guarded. The symptoms of asbestosis are not immediate and often present after several decades. However, once the symptoms start, they are progressive and can be debilitating. The majority of patients will develop lung related complications such as:

Risk factors for chronic respiratory insufficiency include:


• Duration and intensity of asbestosis exposure
• Degree of shortness of breath
• Continued use of tobacco
• Combined pulmonary and pleural involvement
• Chest X-ray and CT scan imaging showing honeycombing
• Bronchoalveolar lavage with high number of inflammatory cells


Malignancy
Prolonged exposure to asbestos is known to cause lung cancer and mesotheliomas of the upper respiratory tract (pharynx, larynx), esophagus, kidney and biliary tract. The combination of tobacco and asbestos has a synergistic effect on the development of lung cancer. Individuals who smoke and have asbestosis exposure are at a very high risk for development of lung cancer than people who do not smoke [6].


Asbestosis, when it coexists with other lung disorders like COPD, emphysema, bronchitis, bronchiectasis or idiopathic fibrosis, can severely worsen the symptoms and worsen the quality of life. Most of these patients develop severe dyspnea and have no exercise tolerance. Asbestosis also worsens the symptoms of asthma and over time, even bronchodilators do not have an effective response.
Many studies have shown that asbestosis has a high morbidity and mortality rate. The disorder leads to premature termination of employment and numerous visits to the hospital.

Etiology

Asbestos exposure in most countries occurs during manufacture of the following products:

  • Making asbestos paper for insulation and filters
  • Incorporation of asbestos cement in shingles, sheets, pipes and clapboards
  • Use in motor vehicles brake lining and clutch facings
  • Preparing dry wall products containing asbestos
  • Making of vinyl asbestos floor tiles
  • Manufacture of textile products such as felt, cord, rope and yarn
  • Manufacture of spray products for thermal, acoustic and fireproofing

Occupations with high risk of asbestosis include the following:


• Boilermakers
• Car mechanics who work on brake linings and clutches
• Insulation workers
• Janitors
• Pipefitters
• Plumbers
• Roofers
• Steamfitters
• Welders


When there is uncontrolled removal of asbestos from the environment studies show that even within a few months, individuals can have very high levels of asbestos fibers in the airways.

Epidemiology

Asbestos exposure was significant nearly half a century ago. Almost every country was using asbestos related products and hence many people were exposed to it. By the 1980s, there was awareness of the dangers of asbestos, and thus, the use of asbestos products declined gradually in most western countries. At present, there are no solid data on the number of people somehow exposed to asbestosis. In the USA, experts indicate that there may be less than a few hundred cases of patients presenting with asbestos related lung disease. Strict governmental regulation of use of asbestos products in the home and better means of protecting the worker has significantly reduced the risk of asbestosis development. However, individuals who have been exposed to asbestos in previous decades continue to be at risk for the pneumoconiosis and other related disorders.
In most western countries, the use of asbestosis is strictly regulated. However in developing countries there is evidence that the use of asbestos is not regulated and in fact asbestos related health disease is rapidly increasing. The reason why asbestos continues to be used in developing countries is because it is cheap, readily available and has exceptional insulating properties.

Sex distribution
Age distribution

Pathophysiology

The incidence of asbestosis is variable and greatly dependent on the cumulative dose of inhaled fibers over many years. Those individuals who have high and prolonged exposure tend to have a higher incidence of asbestosis. Every single type of asbestos fiber studied so far has been shown to induce fibrosis of the lung. Inhalation of the crocidolite fibers are also known to cause malignant lesions of the lung and pleura. Fibers which are less than 3 microns tend to induce fibrosis as they are able to penetrate the cell lining. Thicker fibers are incompletely phagocytised and remain in the lung where they continue to generate an inflammatory reaction. Besides influx of inflammatory cells, there is generation of oxygen free radicals which damage the lung enzymes, proteins and endothelial cell lining [5].
The ability of asbestosis fibers to induce inflammation depends on individual susceptibility, immunological factors and respiratory clearance. Overall, people who tend to smoke have poor airway clearance and are more likely to see progression of disease with asbestosis. Asbestos leads to development of intense fibrosis of the lung, which is most common at the bases. In addition, the ongoing inflammation initiates pleural thickening and plaques.
There is also evidence that some people who are exposed to asbestos fibers of the amphibole type may develop an autoimmune reaction, with generation of autoantibodies. Further research shows that asbestos related lung disease is slightly more common in people who have positive serology for antinuclear antibodies. These patients were also more prone to developing more intense fibrosis of the lung and large pleural plaques, then individuals who were seronegative for anti nuclear antibodies.

Prevention

To prevent asbestosis, one needs to restrict the use of asbestos in the home and workplace. Anyone exposed to asbestos must discontinue all further exposure by either changing the job or home. This is to prevent further exposure and decrease the risk of developing asbestos related lung disease. Unfortunately, once asbestos exposure has occurred, the disease continues even though the exposure had discontinued. Smoking cessation is highly recommended.

Summary

Asbestos are naturally occurring fibers that are extremely heat resistant and have superb insulating properties. For decades, these two properties of asbestos have led to its widespread use in the home and industry. Microscopically, asbestos fibers vary from 1-12 microns in size and may be curved (serpentine asbestos) or straight (amphibole). Over the years several subtypes of amphibole fibers have been recognized, namely actinolite, anthophyllite, crocidolite, amosite and tremolite. Of these, chrysotile is by far the most common type of asbestos fiber produced and used in the manufacturing industry. Asbestos was widely used in the industry until reports started to appear in the late 60s that people who were exposed to it were developing severe restrictive lung disease, lung cancer and mesotheliomas. It was not until a decade later that it was finally concluded that asbestos exposure was not benign and hence, its use started to decline in most western countries. In the manufacturing industry, strict guidelines were introduced to limit the levels of asbestos in the environment. Further workers were asked to wear proper garments and masks when working with asbestos related product. The use of asbestos as insulation in the home continued until the late 80s but sporadic reports exist that asbestos can be found in dry wall made in china [2][3][4].

Patient Information

Asbestos was a common product once used in the home and manufacturing industry to make a variety of products. However, because of the risk of developing severe lung disease and cancer, the use of asbestos has declined in most western countries. Today, people who work in the manufacturing industry are at the highest risk, but because of awareness and use of appropriate garments and masks, there has been a significant decrease in asbestos associated lung disease. When uncontrolled asbestos exposure occurs, the inhaled fibers can cause severe lung fibrosis and increase the risk of lung and pleural cancer. The patients usually present several decades after the initial exposure. Treatment is immediate cessation of exposure. Besides oxygen, there is no definitive therapy for asbestosis. Patients need to be monitored for life as some may develop right heart failure, severe lung fibrosis and even cancer.

Self-assessment

References

1. Cullinan P, Reid P Pneumoconiosis. Prim Care Respir J. 2013 Jun;22(2):249-52.
2.Gulati M, Redlich CA. Asbestosis and environmental causes of usual interstitial pneumonia. Curr Opin Pulm Med. 2015 Mar;21(2):193-200.
3.Norbet C, Joseph A, Rossi SS, Bhalla S, Gutierrez FR. Asbestos-Related Lung Disease: A Pictorial Review. Curr Probl Diagn Radiol. 2014 Oct 30. pii: S0363-0188(14)00117-0.
4.Bernstein DM. The health risk of chrysotile asbestos. Curr Opin Pulm Med. 2014 Jul;20(4):366-70.
5.Liu G, Cheresh P, Kamp DW. Molecular basis of asbestos-induced lung disease. Annu Rev Pathol. 2013 Jan 24;8:161-87.
6.Campbell K, Brosseau S, Reviron-Rabec L, Bergot E, Lechapt E, Levallet G, Zalcman G. Malignant pleural mesothelioma: 2013 state of the art]. Bull Cancer. 2013 Dec;100(12):1283-93.
7. Dang GT, Barros N, Higgins SA, Langley RL, Lipton D. Descriptive review of asbestosis and silicosis hospitalization trends in North Carolina, 2002-2011. N C Med J. 2013 Sep-Oct;74(5):368-75.
8. Donaldson K, Poland CA, Murphy FA, MacFarlane M, Chernova T, Schinwald A. Pulmonary toxicity of carbon nanotubes and asbestos - similarities and differences. Adv Drug Deliv Rev. 2013 Dec;65(15):2078-86.
9. Prazakova S, Thomas PS, Sandrini A, Yates DH. Asbestos and the lung in the 21st century: an update. Clin Respir J. 2014 Jan;8(1):1-10.

  • Asbestos-induced pleural fibrosis and impaired lung function - DA Schwartz, LJ Fuortes, JR Galvin - American Journal of , 1990 - Am Thoracic Soc
  • Asbestos exposure and neoplasia - IJ Selikoff, J Churg, EC Hammond - Jama, 1964 - faculty.smu.edu
  • Asbestosis: assessment by bronchoalveolar lavage and measurement of pulmonary epithelial permeability. - AR Gellert, JA Langford, RJ Winter, S Uthayakumar - Thorax, 1985 - thorax.bmj.com
  • A rare case of classic biphasic pulmonary blastoma - SM Schulze, S Sbayi, JT Costic - The American , 2005 - ingentaconnect.com
  • Asbestos exposure, pleural mesothelioma, and serum osteopontin levels - HI Pass, D Lott, F Lonardo, M Harbut - England Journal of , 2005 - Mass Medical Soc
  • A case of pulmonary asbestosis presenting with temporal arteritis involving multiple medium-sized vessels - S Hirata, N Hattori, N Ishikawa, K Fujitaka - Modern , 2008 - Springer
  • Accelerated loss of lung function and alveolitis in a longitudinal study of non‐smoking individuals with occupational exposure to asbestos - WN Rom - American journal of industrial medicine, 1992 - Wiley Online Library
  • A follow-up study of workers from an asbestos factory - PC Elwood, AL Cochrane - British journal of industrial medicine, 1964 - oem.bmj.com
  • A study of the histological cell types of lung cancer in workers suffering from asbestosis in the United Kingdom - F Whitwell, ML Newhouse, DR Bennett - British journal of industrial , 1974 - oem.bmj.com
  • Chronic pulmonary hypertension‐the monocrotaline model and involvement of the hemostatic system - AE Schultze, RA Roth - and Environmental Health, Part B Critical , 1998 - Taylor & Francis
  • Abnormal pulmonary function associated with diaphragmatic pleural plaques due to exposure to asbestos. - KH Kilburn, RH Warshaw - British journal of industrial medicine, 1990 - oem.bmj.com
  • A randomized controlled study of a home health care team. - JG Zimmer, A Groth-Juncker - American Journal of , 1985 - ajph.aphapublications.org
  • Assessment of progression of asbestosis in the sheep model by bronchoalveolar lavage and pulmonary function tests. - R Begin, M Rola-Pleszczynski, S Masse, D Nadeau - Thorax, 1983 - thorax.bmj.com
  • Asbestos pleurisy - HB Eisenstadt - CHEST Journal, 1964 - journal.publications.chestnet.org
  • Asbestos fibers in laryngeal tissues - A Hirsch, MD Bignon - Med Sci, 1977 - journal.publications.chestnet.org
  • Asbestos bodies in carcinoma of colon in an insulation worker with asbestosis - A Ehrlich, AN Rohl, EC Holstein - JAMA: the journal of the American , 1985 - Am Med Assoc
  • Asbestos, asbestosis, pleural plaques and lung cancer - G Hillerdal, DW Henderson - Scandinavian journal of work, environment & , 1997 - JSTOR
  • Carbon nanotubes introduced into the abdominal cavity of mice show asbestos-like pathogenicity in a pilot study - CA Poland, R Duffin, I Kinloch, A Maynard - Nature , 2008 - nature.com
  • A Case of Pulmonary Asbestosis - KT Woodsides - Journal of Occupational and Environmental , 1967 - journals.lww.com
  • Asbestos pleural effusion. - EA Gaensler, AI Kaplan - Annals of internal medicine, 1971 - ncbi.nlm.nih.gov
  • Analysis of the differential diagnosis and assessment of pleuritic chest pain in young adults - WT Branch, BJ McNeil - The American journal of medicine, 1983 - Elsevier
  • Case of tuberculous pleurisy with eosinophilic pleural effusion and hematological eosinophilia]. - E Kato, N Yamada, T Sugiura - Kekkaku:[Tuberculosis], 2007 - ncbi.nlm.nih.gov
  • Diffuse interstitial pulmonary disease from the perspective of the clinician. - RA DeRemee - Chest, 1987 - chestjournal.chestpubs.org
  • Absence of synergism between exposure to asbestos and cigarette smoking in asbestosis. - JM Samet, GR Epler, EA Gaensler - The American review of , 1979 - ncbi.nlm.nih.gov
  • 24 years of pneumoconiosis mortality surveillance in Australia - DR Smith, PA Leggat - Journal of occupational health, 2006 - J-STAGE
  • Dust levels and dust-induced diseases in the main dust-producing industries - M Dobreva, T Burilkov, S Ivanova, L Mikhaĭlova - Problemi na , 1990 - ukpmc.ac.uk
  • Cardiac Complications of Progressive Generalized Vaccinia Report of a Case - MC McNalley, Y Qamar - CHEST Journal, 1966 - journal.publications.chestnet.org
  • Application of polarized microscopy and analytic electron microscopy in pneumoconiotic pathologic examination]. - BS Wang - Zhonghua jie he he hu xi za zhi= Zhonghua jiehe he , 1989 - ncbi.nlm.nih.gov
  • Asbestosis associated with bronchogenic carcinoma - R STOLL, R BASS, AA ANGRIST - Archives of Internal Medicine, 1951 - Am Med Assoc
  • Anesthesiafor congenital heartsurgery Classification, diagnosis and management of drug-induced respiratory disease - JA DINARDO - Drug-Induced and Iatrogenic Lung Disease~ autofilled - books.google.com
  • Abnormal lung function associated with asbestos disease of the pleura, the lung, and both: a comparative analysis. - KH Kilburn, RH Warshaw - Thorax, 1991 - thorax.bmj.com
  • A case of asbestosis - YS Lee, TW Jang, HD Yu, MH Jung, YH Lee - Korean Journal of , 1999 - KoreaMed
  • Acute pleurisy in asbestos exposed persons - GK Sluis-Cremer, I Webster - Environmental research, 1972 - Elsevier
  • A new look at pattern recognition of diffuse pulmonary disease - B Felson - American Journal of Roentgenology, 1979 - Am Roentgen Ray Soc
  • OBSERVATIONS OF THE DUST CONTENT AND COMPOSITION IN LUNGS WITH ASBESTOSIS, MADE DURING WORK ON COAL MINERS PNEUMOCONIOSIS* - G Nagelschmidt - Annals of the New York Academy of , 2006 - Wiley Online Library
  • Anatomo-histological features of the principal pneumoconioses (anthracosis, silicosis, asbestosis) and their evaluation with respect to cor pulmonale, - DV CESARIS, O LINOLI - Archivio di medicina mutualistica, 1960 - ncbi.nlm.nih.gov
  • Black spots concentrate oncogenic asbestos fibers in the parietal pleura. Thoracoscopic and mineralogic study. - C Boutin, P Dumortier, F Rey, JR Viallat - American journal of , 1996 - Am Thoracic Soc
  • A case of pneumoconiosis - HE Seiler - British Medical Journal, 1928 - bmj.com
  • A diagnostic approach to asbestosis, utilizing clinical criteria, high resolution computed tomography, and gallium scanning - VE Klaas - American journal of industrial medicine, 1993 - Wiley Online Library
  • A case of primary malignant pericardial mesothelioma - DD Lagrotteria, B Tsang, LJ Elavathil, CW Tomlinson - Can J Cardiol, 2005 - ukpmc.ac.uk
  • Absence of synergism between exposure to asbestos and cigarette smoking in asbestosis. - JM Samet, GR Epler, EA Gaensler - The American review of , 1979 - ncbi.nlm.nih.gov
  • 46 Chest Examination - PG TUTEUR - Clinical methods: the history, physical, and , 1990 - ncbi.nlm.nih.gov
  • Asbestos exposure, pleural mesothelioma, and serum osteopontin levels - HI Pass, D Lott, F Lonardo, M Harbut - England Journal of , 2005 - Mass Medical Soc
  • ASBESTOSIS AMONG HOUSEHOLD CONTACTS OF ASBESTOS FACTORY WORKERS* - HA Anderson, R Lilis, SM Daum - Annals of the New York , 1979 - Wiley Online Library
  • Asbestos, asbestosis and mesothelioma of the pleura. - WJ Smither - Proceedings of the Royal Society of Medicine, 1966 - ncbi.nlm.nih.gov
  • Chest radiography in desquamative interstitial pneumonitis: a review of 37 patients - DS Feigin, PJ Friedman - American Journal of , 1980 - Am Roentgen Ray Soc
  • Asbestos exposure, pleural mesothelioma, and serum osteopontin levels - HI Pass, D Lott, F Lonardo, M Harbut - England Journal of , 2005 - Mass Medical Soc
  • Abnormal spontaneous rosette formation and rosette inhibition in lung carcinoma - RL Gross, A Latty, EA Williams - New England Journal , 1975 - Mass Medical Soc
  • An overview of how asbestos exposure affects the lung - GP Currie, SJ Watt, NA Maskell - BMJ, 2009 - bmj.com
  • Acute pneumonitis with bilateral pleural effusion after talc pleurodesis. - A Bouchama, J Chastre, A Gaudichet - CHEST , 1984 - journal.publications.chestnet.org
  • Asbestos induced diffuse pleural fibrosis: pathology and mineralogy. - M Stephens, AR Gibbs, FD Pooley, JC Wagner - Thorax, 1987 - thorax.bmj.com
  • Asbestosis & Asbestos-Related Pleural Disease - ME Hanley, CH Welsh - Current Diagnosis & Treatment in , 2003 - accessmedicine.com
  • Centrilobular opacities in the lung on high-resolution CT: diagnostic considerations and pathologic correlation. - JF Gruden, WR Webb - American Journal of , 1994 - Am Roentgen Ray Soc
  • Asbestos-associated diseases in a cohort of cigarette-filter workers - JA Talcott, WA Thurber, AF Kantor - England Journal of , 1989 - Mass Medical Soc
  • Benign asbestos pleural effusion: diagnosis and course. - BW Robinson, AW Musk - Thorax, 1981 - thorax.bmj.com
  • Occupational and paraoccupational history.......................................... 8 3.2 Apply four specific criteria to make the diagnosis of asbestosis.................. 9 3.3 Use - JS Webber - CME - piermedicine.acponline.org
  • Cement, asbestos, and cement-asbestos pneumoconioses. - G Scansetti, GC Coscia, W Pisani - of environmental health, 1975 - ncbi.nlm.nih.gov

Media References

  1. Asbestosis - Fibrous pleural plaque (7468458430), CC BY-SA 2.0

Languages

Self-assessment