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Cobalt
Description: Cobalt (C.A.S. 7440-48-4) is a metal that occurs naturally in many different chemical forms. Small amounts of cobalt are found in most rocks, soil, surface and underground water, plants, and animals. It usually occurs in association with other metals such as copper, nickel, manganese, and arsenic. After rocks containing cobalt are mined, cobalt removed from the rocks is usually changed into other chemical forms. Cobalt is not currently mined in the United States. Natural sources of cobalt in the environment are soil and dust, seawater, volcanic eruptions, and forest fires. Manufactured sources of cobalt in the environment are the byproducts of burning coal and oil; exhaust from cars, trucks, and aircraft; industrial processes that use the metal or its compounds; and sewage sludge from cities. Pure cobalt is a steel-gray to black, shiny, hard metal with no odor. It is mostly used to make superalloys, which maintain their strength at high temperatures approaching their melting points; as a drier for paint; as a magnetic alloy; as a cutting and wear-resistant alloy; as a ground coat for porcelain enameling used on steel bathroom fixtures and large appliances; as a glass decolorizer; and as an ingredient of colored pigments. Vitamin B-12 is a cobalt-containing compounds that is essential for good human health. Cobalt alloys are used to make artificial parts, such as hip and knee joints, that are placed in human bodies by surgery. In the 1960s, some breweries added cobalt to beer to stabilize the foam, but no longer do so. Some people who drank excessive amounts of the cobalt-enhanced beer experienced serious heart problems, including death. Chemical properties: Cobalt belongs to Group VIII, or the first transitional series, of the periodic classification of elements. Pure cobalt does not dissolve in water but is soluble in acids. It is incompatible or reactive with acetylene, hydrazinium nitrate, ammonium nitrate, and oxidants. It is a moderate fire hazard when exposed to heat or flame or by spontaneous chemical reaction. Natural cobalt can stay in the air for a few days, but it will stay for years in water and soil. Synonyms for cobalt include ACO 4; aquact; C.I. 77320; C.I. 77320; CO 0138E; cobalt element; cobalt fulleride (C0C20); cobalt metal dust; cobalt metal fume; cobalt-59; NCI-C60311; and super cobalt. Identification: Health effects: Cobalt has both beneficial and harmful effects on human health. It is part of vitamin B-12, which is essential to good human health, and has been used as a treatment for anemia, particularly in pregnant women, because it causes red blood cells to be produced. Exposure to cobalt through inhalation, ingestion, or contact with the skin can cause lung effects, including respiratory irritation and hypersensitivity, coughing, dyspnea, fibrosis, asthma, pneumonia, and wheezing; cardiovascular effects, including cardiomyopathy; liver and kidney congestion; ocular effects, including congestion of the conjunctiva; skin rashes; allergies; and weight loss. People who work in the coal mining and hard metal industry, cobalt dye painters in porcelain factories, and workers in the ore processing and chemical manufacturing industries may be exposed to cobalt inhalation at higher than background levels. Exposure Values: Economics: U.S. manufacturers of cobalt are Alfa Products, Morton Thiokol Inc, Danvers, MA; Atlantic Equip Engrs, Bergenfield, NJ; Atlantic Metals & Alloys, Inc, Old Greenwich, CT; Atomergic Chemetals Corp, Plainview, NY; Belmont Metals Inc, Brooklyn, NY; Cerac, Inc, Milwaukee, WI; Consolidated Astronautics Inc, Smithtown, NY; Cotronics Corp, Brooklyn, NY; Ney Products, Inc, Brooklyn, NY; Pfizer Minerals, Pigments & Metals Div, New York, NY; Philipp Brothers Chemicals Inc, New York, NY; Reade Metals & Minerals Corp, Rumson, NJ; United Mineral & Chem Corp, New York, NY; Var-Lac-Oid Chem Co, Bergenfield, NJ; Anderson Physics Laboratories, Inc, Urbana, IL; Noah Chemical Div, San Antonio, TX; CP Chemicals Inc, Fort Lee, NJ; Gallard-Schlesinger Industries, Inc, Carle Place, NY; Ruger Chemical Co, Inc, Irvington, NJ; GFS Chemicals, Columbus, OH; International Nickel, Inc, Saddlebrook, NJ; and Metalspecialties, Inc, Fairfield, CT. Regulation: Releases of cobalt dust and fumes into the air are regulated by the Occupational Safety and Health Administration (OSHA). The EPA Office of Emergency and Remedial Response regulates cobaltous bromide, cobaltous formate, and cobaltous sulfamate, requiring reportable quantities of 1,000 pounds each. Cobalt is also regulated under the Clean Air Act, and the Emergency Planning and Community Right-to-Know Act (EPCRA). Under Section 313 of the Emergency Planning and Community Right to Know Act of 1986, releases of more than one pound of cobalt 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 |