METHACRYLIC ACID BACKGROUND INFORMATION ABOUT THIS PAMPHLET Methacrylic acid and its esters have proven to be versatile chemicals with widespread use. Rohm and Haas, and others, have sponsored and conducted scientific studies on the health and environmental effects of these products. This pamphlet provides a summary of regulatory, exposure, and technical information for use by government officials, health professionals, and others who would like a brief introduction to the data. This pamphlet includes data that Rohm and Haas is aware of as of the date of publication. Rohm and Haas has been careful to accurately summarize the data and conclusions. However we are making this information available to you without any guarantee that they are appropriate for your purposes as conditions and methods of use of our products are beyond our control. In addition, newer data may be or become available. Rohm and Haas disclaims any liability for use of this information by persons outside of Rohm and Haas. Users should also consult the Material Safety Data Sheet (MSDS) and other available brochures for up-to-date information and precautions for safe handling and use of these chemical products. If additional information is desired, please contact your Rohm and Haas Account Manager or the appropriate Regulating Agency for assistance.
INTRODUCTION Methacrylic acid serves as an essential building block in the production of some of our most commonly used industrial and consumer products. Methacrylic acid is used in the chemical industry for the production of methacrylic acid esters and as co-momer in various polymers. The main use of methacrylic acid is in the preparation of methyl methacrylate and other methacrylate esters by direct esterification. In addition, methacrylic acid is used in the preparation of carboxylated polymers and emulsion polymers for paints, adhesives and textile applications Polymerization Methacrylic momers are highly reactive chemicals and, therefore, are useful, nearly exclusively as intermediates in the production of other materials. For example individual molecules of methacrylic acid or esters, called momers, readily combine with themselves or other momers to form long chains of repeating units, or polymers. The polymers have completely different physical and chemical properties than the constituent momers. These polymers can be used in the production of goods that for decades have provided added benefits and convenience to consumers and manufacturers worldwide. PHYSICAL PROPERTIES Methacrylic acid is a clear, colorless, corrosive liquid. Molecular Weight 86.09 Molecular Formula C 4 H 6 O 2 CAS Number 79-41-4 Boiling Point ( C) 159-163 Freezing Point ( C) 14-16 Density (20/20 C) 1.015 Flash Point (Tag Closed Cup C) 77 Page 2
EXPOSURE TO METHACRYLIC ACID Methacrylic acid vapor has a very strong acrid odor that allows for early detection of any potential releases. The following table contains a list of current standards for levels to which the standard-setting bodies consider that most workers can be exposed during an 8-hour workday without harmful effects, as well as the results of tests used to determine the levels at which methacrylic acid usually will be smelled. As illustrated, methacrylic acid odor usually will be detected before it reaches the levels of the current standards. While unpleasant, smelling methacrylic acid vapor is t necessarily indicative that such levels have been exceeded. ACGIH Threshold Limit Value (TLV) (ppm) OSHA Exposure Limit (ppm) 20 20 Odor Threshold (ppm) 5 Because consumer products contain only trace levels of methacrylic acid as a result of the polymerization process, consumers are t generally exposed to these compounds in finished products. Although potential for exposure does exist during methacrylic acid manufacture, transportation, and use, the exposure to worker populations and nearby communities is limited by the use of enclosed systems. Employees and contractors involved in methacrylic acid manufacturing should wear appropriate safety equipment and undergo special training. In spite of the manufacturer s efforts to contain the manufacturing process, vapors can potentially escape from leaks in the piping system (including tanks and reactors), during repair or replacement of the piping system, or during removal of samples for quality control purposes. Worker exposure is monitored in manufacturing facilities with specialized monitoring systems. Since odors can be detected at low levels, it is expected that leaks should be detected and repaired before methacrylic acid can cause adverse health effects. Exposure could also occur during loading, unloading, and transportation of tank trucks, railroad tankers, barges, and drums. However, dedicated systems designed to handle methacrylic acid are typically used for loading and unloading purposes and procedures should be in place to minimize spills or leaks during transportation. Page 3
TOXICOLOGY PROFILE The likely primary routes of potential human exposure to methacrylic acid are skin contact and inhalation; toxicity is due to tissue damage at the site of contact. Undiluted methacrylic acid is a corrosive liquid that can cause permanent tissue damage upon direct contact with the body. Contact with dilute solutions of methacrylic acid or methacrylic acid vapor can be irritating to the skin, eyes and respiratory tract. In animal studies, the irritation caused by repeated exposure to methacrylic acid vapor has resulted in nasal lesions including rhinitis. Methacrylic acid has t been shown to cause skin sensitization (allergic reaction). Such studies have shown that once absorbed, methacrylic acid is rapidly broken down and eliminated, primarily in expired air as carbon dioxide. Toxicity associated with repeated exposures of experimental animals to methacrylic acid typically has been comprised of changes in body and organ weights. Except for dermal and nasal lesions which have been observed at the site of contact, the microscopic examination of other body tissues post-exposure has been generally unremarkable and has indicated significant difference compared to n-exposed animals. Toxic effects after dermal or oral application routes are unkwn. No cancer studies on methacrylic acid are available. However, based on data from the methyl ester of methacrylic acid, methyl methacrylate, toxicologist believe there is concern of carcigenic properties for methacrylic acid. Methyl methacrylate data can be taken into consideration since it would be expected to rapidly break down in the body to form methacrylic acid (relatively rapid ester cleavage by carboxylesterases). Methacrylic acid is t considered hazardous to the reproductive system or to the unborn fetus based on studies with methyl methacrylate. Methacrylic acid is considered moderately toxic to fish and invertebrates following acute exposure. Methacrylic acid does t accumulate in the environment. If released to surface water, methacrylic acid should all be rapidly biodegraded; some portion may volatilize to the air. Page 4
REGULATORY STANDARDS The manufacture, transportation, and use of methacrylic acid are regulated or addressed by a number of government agencies and other expert groups to control exposure to workers and the environment. The following table records major U.S. federal regulatory and similar information as of December 2007. Such regulations frequently change, and many states and localities adopt their own regulations. Therefore, you should consult applicable laws and regulations, as well as the manufacturer s MSDS, for current requirements. REGULATORY STANDARDS OSHA PEL 20 ppm ACGIH TLV 20 ppm IARC N/A NTP BRC DOT Hazard Class Corrosive, flammable SARA/CERCLA RQ SARA 313 RCRA CAA CWA FDA 1 Yes 1 NFPA Rating: 2 Health 3 Flammability 2 Reactivity 2 1 Methacrylic acid used as a momer to make specific polymers is listed for certain specific indirect food additive uses. 2 NFPA Rating Definitions: 3/Health=Materials extremely hazardous to health, but areas may be entered with extreme care; 2/Flammability =Materials that must be moderately heated before ignition will occur; 2/Reactivity=Materials that (in themselves) are rmally unstable and readily undergo violent chemical change but do t detonate. Page 5
ACRONYMS ACGIH TLV CAA CWA DOT Hazard Class FDA IARC NFPA NTP BRC OSHA PEL RCRA SARA/CERCLA RQ SARA 313 American Conference of Governmental Industrial Hygienists, Threshold Limit Value Clean Air Act, 112(b) Clean Water Act, 116.4, 112 App. D, 131.36, 401.15, 423 App. A. Department Of Transportation: Hazard Class 49 C.F.R. 172.101 Food & Drug Administration: 21 C.F.R. Parts 174 to 178 International Agency for Research on Cancer National Fire Protection Association National Toxicology Program Biennial Report on Carcigens Occupational Safety and Health Administration, Permissible Exposure Limit, 29 C.F.R., Table Z, 1910.1200 Resource Conservation and Recovery Act, 40 C.F.R. 261.33 Superfund Amendments and Reauthorization Act (1986), 40 C.F.R. 375/Comprehensive Environmental Response, Compensation, & Liability Act (1980), 40 C.F.R. 302.4 Reportable Quantity Section 313 of Title III of SARA - Toxic Release Inventory Reporting & Community Right-To-Kw, 40 C.F.R. 72. Page 6