Graphite is a variety (a-C) of carbon crystallization. It is stable under normal pressures and temperatures. Another well known variety is the high pressure-formed diamond (ßC), which is metastable under normal physical conditions; compare to diamond. Technically, the flake (diameter of plate >1 mm) is subdivided into amorphous varieties (diameter of plates <1 mm), dust (diameter <100 µm), and pieces of graphite, which are also called Ceylon lumps. Graphite is, in addition, produced synthetically by subjecting coal or petroleum coke to a temperature of 2200-3000° C in an electrical furnace.
Ceylon lumps, Plumbago; Carbon lung, Graphitosis.
It is the chemical element C with additional components of other elements and contaminates of silica (<11%).
It has a layered Structure. The layers are created by hexagonal rings of C-atoms. The stacking of the layers is distorted and induce different variations. The most common variety (graphite-2H) has a 1-2-1-2-1 stacking of the sheets and is hexagonal. The rhomboedric variety has a 1-2-3-1-2-3 stacking (graphite-3 R). Soot (graphite-1 Hd) has probably a one-layered poorly oriented Structure.
Mined in Austria, Brazil, Canada, Korea, Finland (Pargas), Germany, Italy, Madagascar, Mexico, Norway, Russia (Zdanov), Sri Lanka, the USA (Alabama). The world reservoir of natural graphite has been estimated to 100×106 tons.
• Lamp black
Lamp black is amorphous carbon (used as paint pigment or oil-adsorption agent). The diameter of the particles measures 50-120 nm.
• Carbon black
Carbon black is crystalline C that contains polycyclic aromatic hydrocarbons (used in rubber industries, plastics, paints, enamels, carbon electrodes, and in carbon paper. Its usage is known since the late paleolithic age).
Fibrogenic, possibly carcinogenic (carbon black).
Lung, possibly stomach.
Tonatural graphite, exposure may occur during mining and in steel production. It is used in chemical industries, for lubricants, in pencils, paints, as a stove polish, and in carbon electrodes. To synthetic graphite, exposure may occur during the production process. It is used as shields against radioactivity (neutron moderator), and in carbon electrodes. Associated diseases are rare; about 600 cases have been reported.
United States: ACGIH
United States: NIOSH/OSHA
Graphite may induce a pneumoconiosis called carbon pneumoconiosis. The content of silica or the balance between the different components of the dust is assumed to induce the pneumoconiosis; however, a few cases without contamination to silica have been reported. The usually inert carbon particles are ingested by macrophages and deposited around the terminal bronchioles. The deposits induce an enlargement of the distant air spaces (proximal acinar emphysema); the etiology of massive fibrosis still remains unclear. The pulmonary defense system may be altered by ingested carbon particles, and increased IgA and IgG serum levels in coal miners with massive fibrosis have been reported. The increased risk of lung cancer and stomach cancer is assumed to be related with exposure to polycyclic aromatic hydrocarbons.
Usually simple pneumoconiosis, rarely massive fibrosis, possibly lung cancer.
The symptoms include shortness of breath during exercise, cough, dyspnea, chest pain, and findings related to fibrosis and lung cancer.
Chest radiographs show opacities predominantly in the upper lobes.
The Lung Function may display restrictive or obstructive anomalities.
The lavage fluid can contain an increased number of inflammatory cells and black coal particles.
Simple pneumoconiosis will present with multiple well defined black nodules measuring several centimeters in maximum diameter. The lungs of complicated pneumoconiosis present with fibrotic bundles and large cystic air spaces.
Dense deposits of black amorphous material in the distant air spaces, predominantly around the bronchioles terminales. Dense collections of partly dust-laden macrophages and histiocytes can be noted in the alveoli and terminal bronchioles. Multinucleated giant cells are an additional finding. Complicated graphite pneumoconiosis displays, in addition, massive interstitial fibrosis, which is associated with pseudocystic enlargement of the distant air spaces. Scattered interstitial mononuclear inflammatory infiltrates indicate a slowly progressive disease.
Usually good, and depending upon the degree of exposure and possible sequelae (rheumatoid involvement, tuberculosis).
An increased rate of stomach cancer in coal miners has been reported.
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