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N-hexane
Description: N-hexane (C.A.S. 110-54-3) is a chemical made from crude oil. It is used in laboratories, primarily when it is mixed with similar chemicals to produce solvents. Common names for these solvents are commercial hexane, mixed hexanes, petroleum ether, and petroleum naphtha. The major use for solvents containing n-hexane is to extract vegetable oils from crops such as soybeans, flax, peanuts, and safflower seed. They are also used as cleaning agents in the textile, furniture, shoemaking, and printing industries, particularly rotogravure printing. N-hexane is also an ingredient of special glues that are used in the roofing, shoe, and leather industries. N-hexane is used in binding books, working leather, shaping pills and tablets, canning, manufacturing tires, and making baseballs. Consumer products that contain small amounts of n-hexane include gasoline, rubber cement, typeover correction fluids, nonmercury thermometers, alcohol preparations, and aerosols in perfumes. N-hexane is also a component of preparations such as paint thinners, general purpose solvents, degreasing agents, or cleaners. Identification: Chemical properties: N-hexane is a colorless liquid with a slightly disagreeable odor. It evaporates very easily into the air and dissolves only slightly in water. It is highly flammable, and its vapors can be explosive. It may be ignited by heat, sparks, and flames. Flammable vapor may spread away from a spill. N-hexane can react vigorously with oxidizing materials such as liquid chlorine, concentrated oxygen, and sodium hypochlorite. It will attack some forms of plastics, rubber, and coatings. It is insoluble in water and miscible with alcohol, chloroform, and ether. It is incompatible with strong oxidizers. Synonyms for n-hexane are hexane and hexyl hydride. Health effects: The only people known to have suffered the health effects of n-hexane were exposed to it at work. Exposure to n-hexane can cause toxicity in peripheral nerves, muscle wasting, and atrophy. It can cause numbness to the feet and hands and muscle weakness in the feet and lower legs, which can lead to paralysis of the arms and legs. It can also cause dermatitis, nausea, confusion, jaundice, and coma. Exposure Values Regulation: N-hexane is regulated under the Emergency Planning and Community Right-to-Know Act, Clean Air Act, and Comprehensive Environmental Response, Compensation, and Liability Act (Superfund). EPA Offices that regulate n-hexane are Air and Radiation, Water, Solid Waste, and Emergency and Remedial Response. In 1994, n-hexane was added to the list of chemicals on the Toxic Release Inventory (TRI). Under the Emergency Planning and Community Right-to-Know Act, releases of more than one pound of n-hexane into the air, water, or land must be reported annually and entered into the 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 |