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Styrene
Description: Pure styrene (C.A.S. 100-42-5) is a colorless liquid that evaporates easily and has a sweet smell. It often contains other chemicals that give it a sharp, unpleasant smell. When it is linked together in long chains, or polystyrene, styrene is used predominantly in the production of polystyrene plastics and resins, such as in insulation or in the fabrication of fiberglass boats; most styrene products contain a residue of unlinked styrene. Styrene is also used to make rubber, and as an intermediate in the synthesis of materials used for ion exchange resins and to produce copolymers such as styrene-acrylonitrile, acrylonitrile-butadiene-styrene, and styrene-butadiene rubber. Products produced from styrene include packaging, electrical and thermal insulation, fiberglass, pipes, automobile parts, drinking cups and other food-use items, and carpet backing. Styrene is also present in combustion products such as cigarette smoke and automobile exhaust. Low levels of styrene occur naturally in a variety of foods, such as fruits, vegetables, nuts, beverages, and meats. Chemical properties: Styrene dissolves in some liquids, but dissolves only slightly in water. It is soluble in alcohol, ether, acetone, and carbon disulfide; it is incompatible with oxidizers, catalysts for vinyl polymers, peroxides, strong acids, and aluminum chloride. Styrene is dangerous when exposed to flame, heat or oxidants; it reacts violently with chlorosulfonic acid, oleum, and alkali metal-graphite, and reacts vigorously with oxidizing materials. It may polymerize if contaminated or subjected to heat; on decomposition, it emits acrid fumes. It usually contains an inhibitor such as tert-butylcatechol. Styrene is quickly broken down in the air, usually within one to two days; it evaporates from shallow soils andsurface water. Styrene that remains in soil or water may be broken down by bacteria. Synonyms for styrene are ethenyl benzene, cinnamene, cinnamenol, NCI-C02200, phenylethene, phenylethylene, styrene monomer, styrol, vinylbenzol, and vinylbenzene. Identification: Health effects: Styrene is classified in EPA’s Toxic Release Inventory (TRI) as a carcinogen. Exposure can be through inhalation, ingestion, or skin or eye contact. The most common health effects from exposure to styrene affect the central nervous and respiratory systems, including depression, concentration problems, muscle weakness, fatigue, unsteadiness, narcosis, defatting dermatitis, and nausea. Exposure may also irritate the nose, throat, and eyes, including severe eye injuries and lachrymation. Populations with potentially high exposures to styrene include people working in various styrene industries, smokers, and those eating a high proportion of foods packaged in polystyrene. Exposure Values: Economics: Styrene has been manufactured in the United States since 1938. U.S. producers of styrene are Huntsman Chemical Corporation, Bayport, TX , Sterling Chemicals, Inc, Texas City, TX, Cos-Mar, Inc, Carville, LA 70721, Dow Chemical USA, Freeport, TX, ARCO Chemical Co, Channelview, TX, Amoco Corp, Production site: Texas City, TX, Chevron Corp, Production site: St James, LA, Rexene Products Co, Production site: Odessa, TX , Westlake Styrene Corporation, Sulfur, LA Regulation: EPA offices regulating styrene are Water Regulations and Standards, Emergency and Remedial Response, Solid Waste, and Toxic Substances. The Food and Drug Administration regulates styrene as a food additive-synthetic flavoring substance, as an indirect food additive, as a component of polymers in paper in contact with dry food, and with a residual styrene monomer limit in polystyrene intended for use in contact with food. Under the 1986 Emergency Planning and Community Right-to-Know Act, releases of more than one pound of styrene into the air, water, or land must be reported annually and entered into the TRI. Under Section 313 of the Emergency Planning and Community Right to Know Act of 1986 releases of more than one pound of styrene 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 |