 |
Also see:
|
Pyridine
Description: Pyridine (C.A.S. 110-86-1) is a colorless liquid with an unpleasant smell which can be made from crude coal tar or from other chemicals. It can also be formed from the breakdown of many natural materials in the environment. It is used as a solvent in paint and rubber preparation and in research laboratories for functions such as extracting plant hormones. Approximately half the pyridine produced is used as an intermediate in making insecticides and herbicides for agricultural applications. Approximately 20% of pyridine produced goes into the production of piperidine, which is commercially significant in the preparation of chemicals used in rubber vulcanization and agriculture. It is also used directly in the denaturation of alcohol and to make many different products such as medicines, vitamins, food flavorings, pesticides, paints, dyes, rubber products, adhesives, and water proofing for fabrics. Chemical properties: Pyridine is flammable and volatile with steam; it mixes very easily with water and is soluble in alcohol, ether, and benzene. When exposed to heat, flame, or oxidizers, pyridine is a fire hazard. It is a severe explosion hazard in the form of vapor, when exposed to flame or spark. When heated to decomposition, it emits highly toxic fumes of cyanides; pyridine can react vigorously with oxidizing materials. It is incompatible and reactive with strong oxidizers and strong acids, and reacts violently with chlorosulfonic acid, maleic anhydride, oleum, perchromates, B-propiolactone, formamide, chromium trioxide, and sulfuric acid. Liquid pyridine easily evaporates into the air. If it is released to the air, it may take several months to years until it breaks down into other compounds. Synonyms for pyridine are azabenzene and azine. Identification: Health effects: Humans can be exposed to pyridine by inhaling it, absorbing it through the skin, ingesting it, or making skin or eye contact with it. The most important health concern for humans exposed to pyridine is damage to the liver. Other health concerns may be neurological effects, renal effects, and irritation of the skin and eyes. Pyridine can cause central nervous system depression, kidney and liver damage, and gastrointestinal upset. Exposure can also cause headaches, nervousness, dizziness, insomnia, nausea, anorexia, frequent urination, and dermatitis. Very few studies have been conducted to determine the other possible effects of pyridine exposure on human health. Exposure Values: Economics: U.S. manufacturer of pyridine is Crowley Tar Products Company, Inc., Kent, OH. Pyridine hydrochloride was produced in 1992 by R.S.A. Corporation, Ardsley, NY, and Zeeland Chemical, Inc., Zeeland, MI. Refined pyridine, all other grades, was produced in 1992 by Reilly Industries, Inc., Indianapolis, IN. Production volumes are not available to avoid disclosure of individual company operations, according to Synthetic Organic Chemicals, United States Production and Sales, 1992, U.S. International Trade Commission. Regulation: Pyridine releases into the air are regulated by the Occupational Safety and Health Administration (OSHA); The Food and Drug Administration (FDA) regulates pyridine as a food additive, or synthetic flavoring substance component of polycarbonate, and as a resin, or indirect food additive. EPA offices regulating pyridine are Emergency and Remedial Response, Solid Waste, and Toxic Substances. Pyridine is regulated by the Resource Conservation and Recovery Act, and the Comprehensive Environmental Response, Compensation and Liability Act. Under Section 313 of the Emergency Planning and Community Right to Know Act of 1986 releases of more than one pound of pyridine 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 |