 |
Also see:
|
Antimony
Description: Antimony (C.A.S. 7440-36-0) is a silvery white, brittle metal of medium hardness that breaks easily. Small amounts of antimony are found in the earth's crust. Antimony ores are mined and then either changed into antimony metal or combined with oxygen to form antimony oxide, a white powder. Antimony metal is too easily broken to be used alone; to make it stronger; it is usually mixed with other metals such as lead and zinc to form mixtures of metals called alloys. These alloys are used in lead storage batteries, solder, sheet and pipe metal, bearings, castings, type metal, ammunition, and pewter. Some antimony alloys expand slightly upon cooling, a valuable property for use in type metal and other castings. Most primary antimony metal, as well as most secondary antimony, goes into antimonial lead, which is used primarily in grid metal for lead acid storage batteries. Other uses in decreasing order of importance are solder, sheet and pipe, bearing ammunition, and cable sheathing. High-purity antimony is used as a dopant in semi-conductors; intermetallic compounds of antimony such as aluminum antimonide, gallium antimonide, and indium antimonide are used for thermoelectric devices such as infrared detectors and diodes. The most common end-use of antimony compounds is antimony trioxide for fire retardation for plastics, textiles, rubber, adhesives, pigments, and paper. Antimony is used in nonmetal products, including enamels for plastics, metal, and ceramics; decolorizing and refining agents in special optical glass and other glasses; stabilizers in plastics; pigments in paints and ceramics; vulcanization agents; ammunition primers; and fireworks. Some trivalent organic antimony compounds are used to treat bilharziasis (schistosomiasis). Antimony compounds include antimony pentasulfide, antimony chloride, antimony pentoxide, antimony potassium tartrate, antimony trichloride, antimony trioxide, antimony trisulfide, and stibine, or antimony hydride, which is formed when antimony is exposed to nascent hydrogen. Chemical properties: Antimony is sometimes referred to as a metalloid, indicating that it displays both metallic and nonmetallic characteristics. Antimony is a moderate fire hazard in the forms of dust and vapor when exposed to heat or flame; it is a moderate explosion hazard in the form of dust when exposed to flame. When heated or on contact with acid, it emits toxic fumes of stibine; stirred antimony halide yields explosive antimony. Antimony metal is stable under ordinary conditions and is not readily attacked by air or water; it is a poor conductor of heat and electricity. The metal is a noncombustible solid in bulk form, but a moderate explosion hazard in the form of dust when exposed to flame. Antimony is incompatible with strong oxidizers, acids, and halogenated acids; it can react moderately to violently with halogens, chlorine dioxide, chlorine trifluoride, and oxidants. Antimony oxide does not evaporate; only a small amount of it will dissolve in water. Synonyms for antimony are antimony black, antimony regulus, C.I. 77050, stibium, antimony powder, antimoine en poudre (DOT French), antimonio en polvo (DOT Spanish), antimony element, and antimony metal. Identification: Health Effects: Exposure to antimony through inhalation or contact with the eyes and skin can cause irritated nose, throat, skin, and mouth; cough; dizziness; headache; nausea; vomiting; stomach cramps; insomnia; anorexia; and inability to smell properly. Toxicological effects of antimony in humans following inhalation or oral exposure are pneumoconiosis, altered EKG readings, increased blood pressure, abdominal distress, ulcers, dermatosis, and ocular irritation. Exposure to antimony trichloride can result in cardiac abnormalities. Antimony has been used as a medicine to treat people infected with parasites; when too much of that medicine has been used, it has resulted in diarrhea, joint and/or muscle pain, vomiting, blood problems (anemia), heart problems (altered electrocardiograms), and even death. Individuals with existing chronic respiratory or cardiovascular disease or problems could be at special risk to antimony, since antimony probably exacerbates one or both types of health problems. Because antimony is excreted in the urine, individuals with kidney dysfunction may be unusually susceptible. People who live or work near sources of antimony such as smelters, coal-fired power plants, and refuse incinerators may be exposed to high levels of antimony in airborne dust, soil, and vegetation. People who live near or work at waste sites that receive slag from smelters or fly ash from power plants and refuse incinerators may also be exposed to higher than background levels. Workers in battery-forming areas of lead-storage battery plants may be exposed to high levels of stibine. Exposure Values: Economics: U.S. manufacturers of antimony are ASARCO Incorporated, Omaha, NE; Amspec Chemical Corporation, Glouchester City, NJ; Anzon, Inc., Laredo, TX; Laurel Industries Inc., La Porte, TX; Sunshine Mining Co., Kellogg, ID; U.S. Antimony Corp., Thompson Falls, MT. Regulation: EPA's Office of Emergency and Remedial Response issues regulations for antimony. Antimony compounds are regulated by Clean Water Effluent Guidelines for the following industrial point sources: nonferrous metal manufacturing, steam electric, asbestos, timber products processing, mineral mining, paving and roofing, paint formulating, ink formulating, gum and wood, carbon black, and nonferrous metal forming. Antimony compounds are also regulated by the Clean Air Act. Under Section 313 of the Emergency Planning and Community Right to Know Act of 1986, releases of more than one pound of antimony into the air, water, and land must be reported annually and entered into the Toxic Release Inventory (TRI). National Overview of 1998 Toxics Release Inventory See EPA's Toxic Release Inventory. Notations: The NIOSH recommended exposure limits (RELs) are time-weighted average (TWA) concentrations for up to a 10-hour workday during a 40-hour workweek. A short-term exposure limit (STEL) is designated by "ST" preceding the value; unless noted otherwise, the STEL is a 15-minute TWA exposure that should not be exceeded at any time during a workday. A ceiling REL is designated by "C" preceding the value. Any substance that NIOSH considers to be a potential occupational carcinogen is designated by the notation "Ca." The OSHA permissible exposure limits (PEL) are found in Tables Z-1, Z-2, and Z-3 of the OSHA General Industry Air Contaminants Standard (29 CFR 1910.1000). Unless noted otherwise, PEL are TWA concentrations that must not be exceeded during any 8-hour workshift of a 40-hour workweek. A STEL is designated by "ST" preceding the value and is measured over a 15-minute period unless noted otherwise. OSHA ceiling concentrations (designated by "C" preceding the value) must not be exceeded during any part of the workday; if instantaneous monitoring is not feasible, the ceiling must be assessed as a 15-minute TWA exposure. In addition, there are a number of substances from Table Z-2 (e.g., beryllium, ethylene dibromide, etc.) that have PEL ceiling values that must not be exceeded except for specified excursions. For example, a "5-minute maximum peak in any 2 hours" means that a 5-minute exposure above the ceiling value, but never above the maximum peak, is allowed in any 2 hours during an 8-hour workday. Information Sources:
Originally published in Environment Writer by the National Safety Council. Reprinted with permission. Environment Writer Metcalf Institute for Marine and Environmental Reporting University of Rhode Island Graduate School of Oceanography Office of Marine Programs Narragansett, RI 02882 Tel: 401-874-6211; Fax: 401-874-6485 Disclaimer * Copyright 2002-2006 * All rights reserved. * University of Rhode Island |