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Friday, 11 February 2011 03:48

Bismuth

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Gunnar Nordberg

Occurrence and Uses

In nature, bismuth (Bi) occurs both as the free metal and in ores such as bismutite (carbonate) and bismuthinite (double bismuth and tellurium sulphide), where it is accompanied by other elements, mainly lead and antimony.

Bismuth is used in metallurgy for the manufacture of numerous alloys, especially alloys with a low melting point. Some of these alloys are used for welding. Bismuth also finds use in safety devices in fire detection and extinguishing systems, and in the production of malleable irons. It acts as a catalyst for making acrylic fibres.

Bismuth telluride is used as a semiconductor. Bismuth oxide, hydroxide, oxychloride, trichloride and nitrate are employed in the cosmetics industry. Other salts (e.g., succinate, orthoxyquinoleate, subnitrate, carbonate, phosphate and so on) are used in medicine.

Hazards

There have been no reports of occupational exposure during the production of metallic bismuth and the manufacture of pharmaceuticals, cosmetics and industrial chemicals. Because bismuth and its compounds do not appear to have been responsible for poisoning associated with work, they are regarded as the least toxic of the heavy metals currently used in industry.

Bismuth compounds are absorbed through the respiratory and gastrointestinal tracts. The main systemic effects in humans and animals are exerted in the kidney and liver. The organic derivatives cause alterations of the convoluted tubules and may result in serious, and sometimes fatal, nephrosis.

Gum discolouration has been reported with exposure to bismuth dusts. The insoluble mineral salts, taken orally over prolonged periods in doses generally exceeding 1 per day, may provoke brain disease characterized by mental disorders (confused state), muscular disorders (myoclonia), motor coordination disorders (loss of balance, unsteadiness) and dysarthria. These disorders stem from an accumulation of bismuth in the nerve centres which manifests itself when bismuthaemia exceeds a certain level, estimated at around 50 mg/l. In most cases, bismuth-linked encephalopathy gradually disappears without medication within a period of from 10 days to 2 months, during which time the bismuth is eliminated in the urine. Fatal cases of encephalopathy have, however, been recorded.

Such effects have been observed in France and Australia since 1973. They are caused by a factor not yet fully investigated which encourages the absorption of bismuth through the intestinal mucous membrane and leads to an increase in bismuthaemia to a level as high as several hundred mg/l. The danger of encephalopathy caused by inhaling metallic dust or oxide smoke in the workplace is very remote. The poor solubility of bismuth and bismuth oxide in blood plasma and its fairly rapid elimination in the urine (its half-life is about 6 days) argue against the likelihood of a sufficiently acute impregnation of the nerve centres to reach pathological levels.

In animals, inhalation of insoluble compounds such as bismuth telluride provokes the usual lung response of an inert dust. However, long-term exposure to bismuth telluride “doped” with selenium sulphide can produce in various species a mild reversible granulomatous reaction of the lung.

Some bismuth compounds decompose into dangerous chemicals. Bismuth pentafluoride decomposes on heating and emits highly toxic fumes.

 

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Contents

Preface
Part I. The Body
Part II. Health Care
Part III. Management & Policy
Part IV. Tools and Approaches
Part V. Psychosocial and Organizational Factors
Part VI. General Hazards
Part VII. The Environment
Part VIII. Accidents and Safety Management
Part IX. Chemicals
Using, Storing and Transporting Chemicals
Minerals and Agricultural Chemicals
Metals: Chemical Properties and Toxicity
Resources
Part X. Industries Based on Biological Resources
Part XI. Industries Based on Natural Resources
Part XII. Chemical Industries
Part XIII. Manufacturing Industries
Part XIV. Textile and Apparel Industries
Part XV. Transport Industries
Part XVI. Construction
Part XVII. Services and Trade
Part XVIII. Guides

Metals: Chemical Properties and Toxicity Additional Resources

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Metals: Chemical Properties and Toxicity References

Agency for Toxic Substances and Disease Registry (ATSDR). 1995. Case Studies in Environmental Medicine: Lead Toxicity. Atlanta: ATSDR.

Brief, RS, JW Blanchard, RA Scala, and JH Blacker. 1971. Metal carbonyls in the petroleum industry. Arch Environ Health 23:373–384.

International Agency for Research on Cancer (IARC). 1990. Chromium, Nickel and Welding. Lyon: IARC.

National Institute for Occupational Safety and Health (NIOSH). 1994. NIOSH Pocket Guide to Chemical Hazards. DHHS (NIOSH) Publication No. 94-116. Cincinnati, OH: NIOSH.

Rendall, REG, JI Phillips and KA Renton. 1994. Death following exposure to fine particulate nickel from a metal arc process. Ann Occup Hyg 38:921–930.

Sunderman, FW, Jr., and A Oskarsson,. 1991. Nickel. In Metals and their compounds in the environment, edited by E Merian, Weinheim, Germany: VCH Verlag.

Sunderman, FW, Jr., A Aitio, LO Morgan, and T Norseth. 1986. Biological monitoring of nickel. Tox Ind Health 2:17–78.

United Nations Committee of Experts on the Transport of Dangerous Goods. 1995. Recommendations on the Transport of Dangerous Goods, 9th edition. New York: United Nations.