Carborundum

Classification:

Carborundum is an artificial material, which is of specific technical interest due to its hardness.

Cas:

409-21-2

Synonyms/Trade Names:

Silicon carbide.

Chemistry/Composition:

SiC .

Structure:

Si and C are in a fourfold configuration. The structure consists of layers of Si and layers of C atoms.

Crystallographic Constants:

3.073 3.073 15.08 60.000 60.000 90.000.

Crystal Group:

Hexagonal.

Color:

colorless, yellow to black.

Optical Properties:

nO=2.648 nE=2.691.

Pleochroism:

None.

Powder Diagram:

2.511 2.621 1.311 1.37 (29-1131)
(compare to: 1-1119, 22-1316, 22-1317, 22-1273,22-1319).

Natural Sources:

None.

Medical Importance:

Key Hazards:

Fibrogenic, possibly cancerogenic.

Involved Organs:

Lung.

Exposure/Epidemiology:

SiC is used in zinc distillation kilns, as refractory material, as kiln furniture in clay ceramic industries, as abrasive and in steel production industries (foundry furnaces). The production process includes a temperature-resistant binder (clays, other silicates), and SiC, quartz and carbon are formed into bricks, which are afterwards burned at 1500° C. SO2 may contaminate the atmosphere in production areas. Carborundum is additionally used in a fiber-form, which is produced from trichloromethylsilane: CH3SiCl3 → (1200° C) →SiC+3HCl (compare to man made mineral fibers). A pneumoconiosis in a man working for more than 14 years on a conveyor belt loading with silicon carbide has been reported.

Thresholds:

TWA STEL
mg/m3 mg/m3
Australia 10
Belgium 10
France 10
Great Britain 10
Russia 6
United States: ACGIH 10
United States: NIOSH/OSHA 10

In Germany, carborundum is graded possible carcinogenic according to the class “as though III A” of the MAK

Classification

(“as though” means carcinogenic in animal experiments using intrapleural, intratracheal or intraperitoneal fiber applications).

Etiology/Pathophysiology:

Pulmonary fibrosis may be induced by SiC, if it is contaminated with quartz particles. The quartz is assumed to be the causal agent of the fibrotic process, which is probably triggered by activation of the macrophage fibrogenic factor (for details, see under the heading quartz).

Lung Diseases:

Fibrosis, if contaminated with quartz.

Clinical Presentation:

Patients may present with shortness of breath and dry cough.

Radiology:

Patients may show bilateral-reticular nodular shadows in the chest radiographs. Lung Function impairment seems to be correlated with chest-radiograph densities and smoking history.

Lung Function:

Slight restrictive.

Bronchoalveolar Lavage:

Usually no abnormal findings.

Pathology:

Gross:

Small, black to grayish-white nodules may be distributed over both lungs preferentially involving the proximal lung zones.

Histology:

The alveoli are filled with dust-laden macrophages. A mild mononuclear interstitial infiltrate may be noted as well as birefringent particles and ferruginous bodies.

Prognosis:

Usually good and without serious sequelae.

Additional Diseases:

None.

References:

search Pubmed for Carborundum


Bajpal R, Waseem M, Gupta GS, Kaw JL: Ranking toxicity of industrial dusts by Bronchoalveolar Lavage fluid analysis. Toxicology 73 (1992) 161-167
Begin R, Dufresne A, Cantin A, Masse S, Sebastien P, Perrault G: Carborundum pneumoconiosis. Chest 95 (1989) 842-849
Brakhnova IT: Studies of soviet science: Environmentals hazards of metals. Consultants Bureau, New York (1975)
Cichi B: Pathogenic and carcinogenic properties of silicon carbide. Pol J Occup Med 2 (1989) 87-96
Cukier A, Algranti E, Terra Filho M, Carvalho Pinto RM, Teixera LR, Fiss E, Vargas FS: Pneumoconiosis in abrasive industry workers. Rev Hosp Clin Fac Med Sao Paolo 46 (1991) 180-183
Dufresne A, Sebastien P, Perrault G, Masse S, Begin R: Pulmonary clearance of fibrous and angular SiC particulates in the sheep model of pneumoconiosis. Ann Occup Hyg 36 (1992) 519-530
Dufresne A, Loosereewanich P, Harrigan M, Sebastien P, Perrault G, Begin R: Pulmonary dust retention in a silicon carbide worker. Am Ind Hyg Assoc J 54 (1993) 327-330
Durand P, Begin R, Samson L, Canton A, Masse S, Dufresne A, Pereault G, Laflamme J: Silicon carbide pneumoconiosis: a radiographic assessment. Am J Ind Med 20 (1991) 37-47
Elmes PC: Other isometric mineral dusts pneumoconiosis: silicon carbide. In: JK Howard, FH Tyrer (Eds): Textbook of occupational medicine. Churchill Livingstone, Edinburgh (1987)
Funahashi A, Schlueter DP, Pintar K, Siegesmund KA, Mandel GS, Mandel NS: Pneumoconiosis in workers exposed to silicon carbide. Am Rev Respir Dis 129 (1984) 635-640
Johnson NF, Hoover MD, Thomassen DG, Cheng YS, Dalley A, Brooks AL: In vitro activity of silicon carbide whiskers in comparision to other industrial fibers using four cell culture systems. Am J Ind Med 21 (1992) 807-823
Kayser K: Analytical Lung Pathology. Springer, Heidelberg, New York (1992)
Marcer G, Bernardi G, Bartolucci GB, Mastrangelo G, Belluco U, Camposamposiero A, Saia B: Pulmonary impairment in workers exposed to silicon carbide. Br J Ind Med 49 (1992) 489-493
Ostermann JW, Graves IA, Smith TJ, Hammond SK, Robbins JM: Work related decrement of pulmonary Lung Function in silicon carbide production workers. Br J Ind Med 10 (1989) 708-716