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1,1,2,2-Tetrachloroethane
Description: 1,1,2,2-Tetrachloroethane (C.A.S. 79-34-5) is a man-made colorless or pale yellow dense liquid with a penetrating, sweet chloroform-like odor. The only major use for it is as a feedstock in the production of trichloroethylene, tetrachloroethylene, and 1,2-dichloroethylene. It may also be used as a solvent; in cleaning and degreasing metals; in paint and rust removers, varnishes and lacquers; in photographic films; and as an extractant for oils and fats. Although 1,1,2,2-tetrachloroethane may be used as an insecticide, fumigant, and weedkiller, it presently is not registered for any of those purposes. It was once an ingredient in an insect repellent, but registration was cancelled in the late 1970s. Due to its toxicity and new processes for manufacturing chlorinated ethylenes, the manufacture and use of 1,1,2,2-tetrachloroethane now appears to be very limited. Information about the chemical is proprietary; therefore, it is not known specifically where it is used, or in what products it is found. Patterns of its use can best be determined from surveys of industrial wastewater. Chemical properties: 1,1,2,2-Tetrachloroethane does not burn easily, but produces poisonous gases in a fire, including phosgene and hydrogen chloride. Most of the chemical released into the environment eventually moves into the atmosphere or groundwater, where its breakdown is slow. Half of it is expected to disappear from groundwater in one to three months, and from the air in about two months. It is soluble in alcohol and ether. Other names for 1,1,2,2-tetrachloroethane are acetylene tetrachloride; dichloro-2,2-dichloroethane; s-tetrachloroethane; TCE tetrachloroethane; and sym-tetrachloroethane. Indentification: Health effects: Overexposure to 1,1,2,2-tetrachloroethane, even short-term, can cause death, unconsciousness, and liver and kidney damage. It is life threatening if it is inhaled or drunk, or if a large amount is spilled onto the skin. Long-term exposure can cause chronic damage of the liver, kidneys, blood-forming organs, and nerves. Breathing highly concentrated fumes of it or drinking small amounts may damage the liver enough to cause death, as well as cause drowsiness, fatigue, stomach aches, nausea, vomiting, weakness, dizziness, and possibly unconsciousness. 1,1,2,2-Tetrachlorethane liquid or vapor can cause eye damage and irritate the skin, nose, mouth, and throat. Short-term exposure may cause nerve effects such as tremors, "pins and needles," headaches, irritability, nervousness, or insomnia. Exposure Values: Though studies available to the U.S. Agency for Toxic Substances and Disease Registry are inconclusive as to whether 1,1,2,2-tetrachlorethane causes cancer in humans, the U.S. Occupational Safety and Health Administration (OSHA) has classified it as a "de minimis" carcinogen, meaning that the minimum amount of the chemical set by OSHA is considered to be carcinogenic. It is listed in the national Toxic Release Inventory (TRI) as a de minimis carcinogen. The general population may be exposed to 1,1,2,2- tetrachloroethane in ambient air, by ingesting contaminated drinking water, or from skin exposure to contaminated soil. Economics: Due to its toxicity and availability of less toxic solvents and to new processes for manufacturing chlorinated ethylenes, the manufacture and use of tetrachloroethane is now very limited. Imports of 1,1,2,2-tetrachloroethane in 1982 totaled 144,000 pounds. Recent data pertaining to the chemical’s import were not available. Regulation: OSHA has established permissible exposure limits for 1,1,2,2-tetrachloroethane. Offices within the U.S. Environmental Protection Agency (EPA) responsible for regulations applicable to the chemical are Water Regulations: and Standards, and Emergency and Remedial Response. Under the Emergency Planning and Community Right-to-Know Act of 1986, releases of more than one pound of 1,1,2,2- tetrachloroethane into the air, water, and land must be reported annually and entered into the national 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 |