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1,1,1-Trichloroethane (Methyl Chloroform)
Description: 1,1,1-Trichloroethane (C.A.S. 71-55-6), also known as methyl chloroform, is a colorless liquid with a sweet, sharp odor. It is a manufactured chemical that does not occur naturally. It is used as a solvent for adhesives and in metal degreasing, pesticides, textile processing, cutting fluids, aerosols, lubricants, cutting oil formulations, drain cleaners, shoe polishes, spot cleaners, printing inks, and strain repellents. In industry, it is widely used for cold-cleaning, dip cleaning, bucket cleaning, and vapor degreasing operations of items such as precision instruments, molds, electrical equipment, motors, electronic components and instruments, missile hardware, paint masks, photographic film, printed circuit boards, generators, switchgears, semiconductors, and high vacuum equipment, fabrics, and wigs. It is used in the electronics industry in circuit board fabrication and in the semi-conductor industry for secondary cleaning. It is also used for on-site cleaning of printing presses, food packaging machinery, and molds. In the home, it may be an ingredient of products such as spot cleaners, glues, and aerosol sprays; it may be found in carpets, spray and solid insecticides, carpet glue, or solid rodenticides. Chemical properties: 1,1,1-Trichloroethane can exist in the form of a liquid or a vapor, or it can be dissolved to varying amounts in water, food, and other chemicals. When heated to decomposition or on contact with acids or acid fumes, it evolves highly toxic chloride fumes. As a liquid in an open container, it evaporates quickly and becomes a vapor in the air. It is insoluble in water, and soluble in acetone, benzene, carbon tetrachloride, methanol, and ether. It is miscible with other chlorinated solvents, and soluble in common organic solvents. It is incompatible or reactive with strong caustics; strong oxidizers; and chemically-active metals such as zinc, aluminum, magnesium powders, sodium, and potassium. It reacts slowly with water to form hydrochloric acid. Synonyms for 1,1,1-trichloroethane are methyl chloroform, chloroethene, chlorothene, methyltrichloromethane, trichloromethylmethane, NC1-C04626, alpha-trichloroethane, and alpha-trichloromethane. Identification: Health effects: 1,1,1-Trichloroethane is one of the solvents that can be intentionally inhaled to alter mood or consciousness; deaths have been attributed to this solvent abuse, associated with "sudden sniffing death" syndrome. Other exposure can be through ingestion or contact with the skin or eyes. Death following acute exposure to high 1,1,1-trichloroethane concentrations is usually attributed to either depression of the central nervous system, which results in respiratory arrest, or sensitization of the heart to epinephrine, which results in severe cardiac arrhythmias. Exposure to high levels of 1,1,1-trichloroethane may also cause respiratory depression, leading to death; dizziness; light-headedness; loss of balance and coordination; unconsciousness; decreased blood pressure; and failure of the heart to beat. Lower levels of exposure can also cause headache, lassitude, irritation to the eyes, and dermatitis. Airtight, highly-insulated houses are likely to have high indoor concentrations of 1,1,1-trichloroethane from the use of household products containing the chemical, exposing inhabitants to potentially high levels. Very high levels of exposure are expected for people who intentionally inhale 1,1,1-trichloroethane for its narcotic properties. 1,1,1-Trichloroethane is used in some adhesive remover pads of incubators in intensive care nurseries, and there is evidence that infants in incubators can be exposed to high concentrations of the chemical. Exposure Value: Economics: 1,1,1-Trichloroethane is manufactured in the U.S. by Dow Chemical USA, Freeport, TX ,PPG Industries, Inc, Lake Charles, LA, Vulcan Materials Co, Birmingham, AL Regulation: Worker exposures to 1,1,1-trichloroethane is regulated by the Occupational Safety and Health Administration (OSHA); with a permissible exposure limit, time-weighted average, is 350 ppm (1,900 mg/m3); short-term exposure limit is 450 ppm (2,450 mg/m3). EPA offices regulating 1,1,1-trichloroethane are Groundwater and Drinking Water, Water Regulations and Standards, Emergency and Remedial Response, Pesticide Programs, Solid Waste, and Toxic Substances. It is classified by EPA as a hazardous air pollutant. 1,1,1-Trichloroethane is regulated under the following laws: Emergency Planning and Community Right-to-Know Act; Clean Air Act; Comprehensive Environmental Response, Compensation, and Liability Act; Federal Insecticide, Fungicide, and Rodenticide Act; National Primary Drinking Water Regulations; Clean Water Act, on the priority pollutant list; and Resource Conservation and Recovery Act. 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 |