Indium lung

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Indium lung
Specialty Pulmonology

Indium lung is a rare occupational lung disease caused by exposure to respirable indium in the form of indium tin oxide. It is classified as an interstitial lung disease (diffuse parenchymal lung disease). [1]

Occupational lung diseases are occupational, or work-related, lung conditions that have been caused or made worse by the materials a person is exposed to within the workplace. It includes a broad group of diseases, including occupational asthma, chronic obstructive pulmonary disease (COPD), bronchiolitis obliterans, inhalation injury, interstitial lung diseases, infections, lung cancer and mesothelioma. These diseases can be caused directly or due to immunological response to a exposure to a variety of dusts, chemicals, proteins or organisms.

Indium Chemical element with atomic number 49

Indium is a chemical element with the symbol In and atomic number 49. Indium is the softest metal that is not considered to be an alkali metal. It is a silvery-white metal that resembles Tin(Sn) in appearance. It is a post-transition metal that makes up 0.21 parts per million of the Earth's crust. Indium has a melting point higher than sodium and gallium, but lower than lithium and tin. Chemically, indium is similar to gallium and thallium, and it is largely intermediate between the two in terms of its properties. Indium was discovered in 1863 by Ferdinand Reich and Hieronymous Theodor Richter by spectroscopic methods. They named it for the indigo blue line in its spectrum. Indium was isolated the next year.

Indium tin oxide chemical compound

Indium tin oxide (ITO) is a ternary composition of indium, tin and oxygen in varying proportions. Depending on the oxygen content, it can either be described as a ceramic or alloy. Indium tin oxide is typically encountered as an oxygen-saturated composition with a formulation of 74% In, 18% O2, and 8% Sn by weight. Oxygen-saturated compositions are so typical, that unsaturated compositions are termed oxygen-deficient ITO. It is transparent and colorless in thin layers, while in bulk form it is yellowish to grey. In the infrared region of the spectrum it acts as a metal-like mirror.


Signs and symptoms

The major signs of indium lung are pulmonary alveolar proteinosis and pulmonary fibrosis. Symptoms include dyspnea (shortness of breath), cough, and increased sputum production. Hemoptysis has also been seen in people with indium lung. [1] Other symptoms seen in some but not all cases include digital clubbing, low DLCO (capacity to move oxygen from the alveoli into the blood), and lowered forced expiratory volume. Emphysema has been associated with indium lung, but may not be part of the syndrome. [2]

Pulmonary alveolar proteinosis lung disease that is characterized by abnormal accumulation of surfactant occurs within the alveoli, interfering with gas exchange

Pulmonary alveolar proteinosis (PAP) is a rare lung disorder characterized by an abnormal accumulation of surfactant-derived lipoprotein compounds within the alveoli of the lung. The accumulated substances interfere with the normal gas exchange and expansion of the lungs, ultimately leading to difficulty breathing and a predisposition to developing lung infections. The causes of PAP may be grouped into primary and secondary causes, although the most common cause is a primary autoimmune condition.

Pulmonary fibrosis human disease

Pulmonary fibrosis is a respiratory disease in which scars are formed in the lung tissues, leading to serious breathing problems. Scar formation, the accumulation of excess fibrous connective tissue, leads to thickening of the walls, and causes reduced oxygen supply in the blood. A consequence is a perpetual shortness of breath.

Sputum mucus that is coughed up from the lower airways

Sputum is mucus and is the name used for the coughed-up material (phlegm) from the lower airways. In medicine, sputum samples are usually used for naked eye exam, microbiological investigations of respiratory infections, and cytological investigations of respiratory systems. It is critical that the patient not give a specimen that includes any mucoid material from the interior of the nose. Naked eye exam of sputum can be done at home by a patient in order to note the various colors. Any hint of yellow color suggests an airway infection. Such color hints are best detected when the sputum is viewed on a very white background such as white paper, a white pot, or a white sink surface. The more intense the yellow color, the more likely it is a bacterial infection.


Lung cancer may be related to indium lung disease, though indium is not a known carcinogen. [1]


Indium lung is caused by exposure to indium tin oxide in a variety of occupational contexts, including reclamation and production. [1] Exposure to indium tin oxide as it reacts can lead to exposure to indium metal, indium hydroxide, and indium oxide.


The exact mechanism of pathogenesis is unknown, but it is hypothesized that indium may exacerbate existing autoimmune disorders or that phagocytosis of indium by alveolar macrophages may cause dysfunction in the macrophages. [2]

Phagocytosis An endocytosis process that results in the engulfment of external particulate material by phagocytes. The particles are initially contained within phagocytic vacuoles (phagosomes), which then fuse with primary lysosomes to effect digestion of the par

Phagocytosis is the process by which a cell uses its plasma membrane to engulf a large particle, giving rise to an internal compartment called the phagosome. It is one type of endocytosis pinocytosis.

Alveolar macrophage macrophage found in the pulmonary alveolus

An alveolar macrophage is a type of macrophage found in the pulmonary alveolus, near the pneumocytes, but separated from the wall.


CT scanning and radiography can be used to aid in the diagnosis of indium lung. CT abnormalities include ground-glass opacities, interlobular septal thickening, honeycombing, and bronchiectasis. [1] [2]

Radiography imaging technique

Radiography is an imaging technique using X-rays, gamma rays, or similar ionizing radiation and non-ionizing radiation to view the internal form of an object. Applications of radiography include medical radiography and industrial radiography. Similar techniques are used in airport security . To create an image in Conventional Radiography, a beam of X-rays is produced by an X-ray generator and is projected toward the object. A certain amount of the X-rays or other radiation is absorbed by the object, dependent on the object's density and structural composition. The X-rays that pass through the object are captured behind the object by a detector. The generation of flat two dimensional images by this technique is called projectional radiography. In computed tomography an X-ray source and its associated detectors rotate around the subject which itself moves through the conical X-ray beam produced. Any given point within the subject is crossed from many directions by many different beams at different times. Information regarding attenuation of these beams is collated and subjected to computation to generate two dimensional images in three planes which can be further processed to produce a three dimensional image.


Honeycombing or "Honeycomb lung" is the radiological appearance seen with widespread fibrosis and is defined by the presence of small cystic spaces with irregularly thickened walls composed of fibrous tissue. Dilated and thickened terminal and respiratory bronchioles produce cystic airspaces, giving honeycomb appearance on chest x-ray. Honeycomb cysts often predominate in the peripheral and pleural/subpleural lung regions regardless of their cause.

Laboratory findings

Multiple abnormal laboratory findings have been noted in indium lung. High levels of serum indium have been found in all cases of indium lung. Other abnormal laboratory values that have been found include elevated alanine aminotransferase, elevated aspartate aminotransferase, elevated C-reactive protein, elevated interstitial lung disease markers, and elevated GM-CSF autoantibodies. [2]


The National Institute of Occupational Safety and Health, Japan (JNIOSH) set limits for acceptable exposure at 0.0003 mg/m3 after the discovery of indium lung. [2] [3] Methods for reducing indium exposure are thought to be the best mode of protection. Medical surveillance of indium workers is also a method of prevention. [2]


There is no standardized treatment for indium lung disease. Treatment options include pulmonary lavage and corticosteroid therapy. [1] [2]


Prognostic factors were a matter of research as of 2012, but preliminary evidence suggests that duration of employment and reported use of respiratory protection are not prognostic factors, but the serum level of indium may be a prognostic factor - higher levels of serum indium have been associated with worse prognoses. Indium lung disease has been fatal in several cases. [2]


It was first described by a group of Japanese researchers in 2003. [1] [4]


Cases have been reported in Japan, the United States, and China. [1] [2] [5] The indium industry is mainly based in Japan, where the bulk of cases have occurred; indium industry is also present in the US, China, Taiwan, and South Korea. [4] As of 2010, 10 cases had been described, though more than 100 indium workers had documented respiratory abnormalities. [1]

Related Research Articles

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Mesothelioma is a type of cancer that develops from the thin layer of tissue that covers many of the internal organs. The most common area affected is the lining of the lungs and chest wall. Less commonly the lining of the abdomen and rarely the sac surrounding the heart, or the sac surrounding the testis may be affected. Signs and symptoms of mesothelioma may include shortness of breath due to fluid around the lung, a swollen abdomen, chest wall pain, cough, feeling tired, and weight loss. These symptoms typically come on slowly.

Pneumoconiosis interstitial lung disease that is caused by the inhalation of dust

Pneumoconiosis is the general term for a class of interstitial lung diseases where inhalation of dust has caused interstitial fibrosis. Pneumoconiosis often causes restrictive impairment, although diagnosable pneumoconiosis can occur without measurable impairment of lung function. Depending on extent and severity, it may cause death within months or years, or it may never produce symptoms. It is usually an occupational lung disease, typically from years of dust exposure during work in mining; textile milling; shipbuilding, ship repairing, and/or shipbreaking; sandblasting; industrial tasks; and/or agriculture.

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  1. 1 2 3 4 5 6 7 8 9 Sauler, Maor; Gulati, Mridu (December 2012). "Newly Recognized Occupational and Environmental Causes of Chronic Terminal Airways and Parenchymal Lung Disease". Clinics in Chest Medicine. 33 (4): 667–680. doi:10.1016/j.ccm.2012.09.002. PMC   3515663 . PMID   23153608.
  2. 1 2 3 4 5 6 7 8 9 Cummings, Kristin J.; Nakano, Makiko; Omae, Kazuyuki; Takeuchi, Koichiro; Chonan, Tatsuya; Xiao, Yong-long; Harley, Russell A.; Roggli, Victor L.; Hebisawa, Akira (June 2012). "Indium Lung Disease". Chest. 141 (6): 1512–1521. doi:10.1378/chest.11-1880. ISSN   0012-3692. PMC   3367484 . PMID   22207675.
  3. The Technical Guideline for Preventing Health Impairment of Workers Engaged in the Indium Tin Oxide Handling Processes (PDF). JNIOSH. 2010.
  4. 1 2 Homma, Toshiaki; Ueno, Takahiro; Sekizawa, Kiyohisa; Tanaka, Akiyo; Hirata, Miyuki (May 2003). "Interstitial pneumonia developed in a worker dealing with particles containing indium-tin oxide". Journal of Occupational Health. 45 (3): 137–139. doi:10.1539/joh.45.137. ISSN   1341-9145. PMID   14646287.
  5. Cummings, Kristin J.; Donat, Walter E.; Ettensohn, David B.; Roggli, Victor L.; Ingram, Peter; Kreiss, Kathleen (March 1, 2010). "Pulmonary alveolar proteinosis in workers at an indium processing facility". American Journal of Respiratory and Critical Care Medicine. 181 (5): 458–464. doi:10.1164/rccm.200907-1022CR. ISSN   1535-4970. PMC   3159086 . PMID   20019344.

Further reading