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Acetaldehyde
Description: Acetaldehyde (C.A.S. 75-07-0) is a colorless liquid with a pungent, fruity odor. It is used primarily as a chemical intermediate, principally for the production of acetic acid, pyridine and pyridine bases, peracetic acid, pentaerythritol, butylene glycol, and chloral. It is used in the production of esters, particularly ethyl acetate and isobutyl acetate. It is also used in the synthesis of crotonaldehyde, flavor and fragrance acetals, acetaldehyde 1,1-dimethylhydrazone, acetaldehyde cyanohydrin, acetaldehyde oxime, and various acetic esters, paraldehyde, metaldehyde (a molluscicide widely used to kill slugs and snails), polymers, and various halogenated derivatives. Acetaldehyde is used in denatured alcohol. In the past it was a chemical intermediate for 2-ethyl-1-butanol, glyoxal, acrolein, and acetaldehyde-aniline condensate. Acetaldehyde has been used in the manufacture of aniline dyes and synthetic rubber, to silver mirrors, and to harden gelatin fibers. It has been used in the production of polyvinyl acetal resins, in fuel compositions, and to inhibit mold growth on leather. It is also used in the manufacture of disinfectants, drugs, perfumes, explosives, lacquers, varnishes, photographic chemicals, phenolic and urea resins, rubber accelerators, antioxidants, and room air deodorizers. It is also a pesticide intermediate. Acetaldehyde is a compound for the intended use as a flavoring agent and adjuvant. It is an important component of food flavorings added to milk products, baked goods, fruit juices, candy, desserts, and soft drinks; the concentration of acetaldehyde in food is usually up to .047%. It is an especially useful synthetic flavoring ingredient to impart orange, apple, and butter flavors and is used as a fruit and fish preservative. Acetaldehyde is a by-product of yeast production and is a naturally occurring compound in wine, bread, soy sauce and other yeast fermented products. It is approved for used in phenolic resins in molded containers for contact with nonacidic foods. Acetaldehyde is exempted from a residue tolerance when it is used as a fumigant for storage of apples and strawberries. Chemical properties: Acetaldehyde is a volatile and flammable liquid. It is miscible in water, alcohol, ether, benzene, gasoline, solvent, naphtha, toluene, xylene, turpentine, acetone, and other common organic solvents. It is a highly reactive compound that undergoes numerous condensation, addition, and polymerization reactions. It is dangerous when exposed to heat or flame; it can react vigorously with oxidizing material, acid anhydrides, alcohols, ketones, phenols, halogens, isocyanates, and strong alkalies and amines. It is also incompatible with acids, bases, alcohol, ammonia, amines, phenols, ketones, and hydrogen cyanide. It will polymerize readily in the presence of trace metals (iron). Acetaldehyde can form unstable or explosive peroxides with exposure to air. It may polymerize under influence of air and heat, acids, or bases with potential of fire or explosion. It is polymerized violently by concentrated sulfuric acid. Rubber products decompose on contact with acetaldehyde, but it is not corrosive to most metals. Synonyms for acetaldehyde are acetic aldehyde, ethanal, NCI-C56326, and ethyl aldehyde. Identification: Health effects: Acetaldehyde is a substance which may reasonably be anticipated to be a carcinogen, according to the Seventh Annual Report on Carcinogens, National Toxicology Program, U.S. Department of Health and Human Services. It is also classified in EPA's Toxic Release Inventory (TRI) to be a known or suspected carcinogen. When ingested or inhaled, acetaldehyde can irritate the eye, nose, and throat; cause conjunctivitis, coughing, central nervous system depression, eye and skin burns, dermatitis, and delayed pulmonary edema. Exposure Values: Economics: U.S. Manufacturers of acetaldehyde are Eastman Chemical Company, Longview, TX ; Hoechst Celanese Corporation, Bay City. Regulation: EPA regulates acetaldehyde under the Clean Air Act; Clean Water Act; Comprehensive Environmental Response, Compensation, and Liability Act (Superfund); Food, Drug, and Cosmetic Act; the Emergency Planning and Community Right-to-Know Act of 1986; Resource Conservation and Recovery Act; and Superfund Amendments and Reauthorization Act. Acetaldehyde is a toxic pollutant of air and water. EPA has established water quality criteria for acetaldehyde, including effluent guidelines, rules for regulating hazardous spills, general threshold amounts, and requirements for handling and disposal of acetaldehyde wastes. A reportable quantity of 1,000 pounds has been established for acetaldehyde under the Clean Water Act and Superfund. Acetaldehyde is exempted under the Food, Drug, and Cosmetic Act from tolerances for pesticide chemicals. Acetaldehyde is regulated as a hazardous constituent of waste under RCRA. The Food and Drug Adminstration regulates acetaldehyde as a direct food additive and a synthetic flavoring substance. Occupational Safety and Health Administration (OSHA): OSHA regulates acetaldehyde under the Hazard Communication Standard and as a chemical hazard in laboratories. Permissible Exposure Limit: Table Z-1 8-hr Time Weighted Avg: 200 ppm (360 mg/cu m). [29 CFR 1910.1000 (7/1/98). The vacated 1989 OSHA PEL TWA 100 ppm (180 mg/cu m); STEL 150 ppm (270 mg/cu m) is still enforced in some states. Under the Emergency Planning and Community Right-to-Know Act of 1986, releases of more than one pound of acetaldehyde into the air, water, or land must be reported annually and entered into the TRI. Facilities having a threshold quantity of 10,000 lbs of acetaldehyde are subject to the Risk Management Program Rule, Section 112r of the Clean Air Act. National Overview of 1998 Toxic 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 |