Isocyanates are compounds containing the isocyanate group (-NCO). They react with compounds containing alcohol (hydroxyl) groups to produce polyurethane polymers, which are components of polyurethane foams, thermoplastic elastomers, spandex fibers, and polyurethane paints. Isocyanates are the raw materials that make up all polyurethane products. Jobs that may involve exposure to isocyanates include painting, foam-blowing, and the manufacture of many Polyurethane products, such as chemicals, polyurethane foam, insulation materials, surface coatings, car seats, furniture, foam mattresses, under-carpet padding, packaging materials, shoes, laminated fabrics, polyurethane rubber, and adhesives, and during the thermal degradation of polyurethane products.
Health effects of isocyanate exposure include irritation of skin and mucous membranes, chest tightness, and difficult breathing. Isocyanates include compounds classified as potential human carcinogens and known to cause cancer in animals. The main effects of hazardous exposures are occupational asthma and other lung problems, as well as irritation of the eyes, nose, throat, and skin.
Isocyanates hazards are addressed in specific standards for general industry, shipyard employment, and the construction industry. This section highlights OSHA standards and standard interpretations (official letters of interpretation of the standards) related to isocyanates. Twenty-five states, Puerto Rico and the Virgin Islands have OSHA-approved State Plans and have adopted their own standards and enforcement policies. For the most part, these States adopt standards that are identical to Federal OSHA. However, some States have adopted different standards applicable to this topic or may have different enforcement policies.
General Industry (29 CFR 1910)
Shipyard Employment (29 CFR 1915)
Construction Industry (29 CFR 1926)
- 1926 Subpart D, Occupational health and environmental controls
- 1926.55, Gases, vapors, fumes, dusts, and mists
- Appendix A, Gases, vapors, fumes, dusts, and mists
- 1926.64, Process safety management of highly hazardous chemicals
- Appendix A, List of highly hazardous chemicals, toxics and reactives (Mandatory)
Many workers are unaware of the potential hazards that chemicals present in their work environment, which makes them more vulnerable to injury. The following references aid in recognizing and evaluating hazards associated with isocyanates in the workplace.
- OSHA Technical Manual (OTM). OSHA Directive TED 01-00-015 [TED 1-0.15A], (1999, January 20).
- Chemical Hazard Communication. OSHA Publication 3084, (Revised 1998). Also available as a 248 KB PDF, 31 pages. Addresses the need for chemical hazard communication and explains why a standard is necessary to minimize workplace hazards.
- Documentation for Immediately Dangerous to Life or Health Concentrations (IDLHs). National Institute for Occupational Safety and Health (NIOSH), (1994, May).
- TOXNET (Toxicology Data Network). National Library of Medicine.
- Report on Carcinogens (RoC). US Department of Health and Human Services (DHHS), National Toxicology Program (NTP). Identifies and discusses agents, substances, mixtures, or exposure circumstances that may pose a health hazard due to their carcinogenicity. The listing of substances in the RoC only indicates a potential hazard and does not establish the exposure conditions that would pose cancer risks to individuals.
- International Agency for Research on Cancer (IARC) Monographs on the Evaluation of Carcinogenic Risks for Humans. World Health Organization (WHO).
- ToxFAQs™ for Methyl Isocyanate. Agency for Toxic Substances and Disease Registry (ATSDR), (2002, April). Summarizes the properties and health effects for methyl isocyanate.
- Integrated Risk Information System (IRIS). Environmental Protection Agency (EPA). Discusses the health effects.
- Health Effects Notebook for Hazardous Air Pollutants. Environmental Protection Agency (EPA).
- Hazardous Substance Fact Sheets. New Jersey Department of Health and Senior Services. Includes detailed reports on specific chemicals, covering hazard summaries, identification, exposure routes, health hazards, and ways of reducing exposure. The following fact sheets cover isocyanate compounds.
- 3-Chloro-4-Methyl Phenyl Isocyanate [105 KB PDF, 6 pages]. (1997, April).
- Hexamethylene Diisocyanate [1 MB PDF, 6 pages]. (1999, April).
- Isophorone Diisocyanate [109 KB PDF, 6 pages]. (1986, January).
- Methylene Bisphenyl Isocyanate [362 KB PDF, 6 pages]. (1998, June).
- Methyl Isocyanate [157 KB PDF, 6 pages]. (1996, April).
- Toluene-2,4-Diisocyanate [155 KB PDF, 6 pages]. (1996, February).
- Toluene-2,6-Diisocyanate [154 KB PDF, 6 pages]. (1996, February).
- International Chemical Safety Cards (ICSC). National Institute for Occupational Safety and Health (NIOSH). Summarizes essential health and safety information.
- Preventing Asthma and Death from Diisocyanate Exposure. US Department of Health and Human Services (DHHS), National Institute for Occupational Safety and Health (NIOSH) Publication No. 96-111, (1996). Discusses the recognition, evaluation, and control of diisocyanate exposures.
- Evaluation of the Effectiveness of Air-Purifying Respirator Cartridges in Removing MDI Aerosols from Air. The Dow Chemical Company, (1997). Shows that organic vapor cartridges without a particulate filter were not effective at removing Methylene bisphenyl isocyanate (MDI) aerosols from air, while organic vapor cartridges with dust/mist (DM) or high efficiency (HEPA) filters effectively removed greater than 99 percent of MDI aerosol and vapor in all test atmospheres.
- The following studies indicate that respiratory sensitivity to isocyanates may be related to previous dermal exposure.
- Kimber, I. "The Role of the Skin in Development of Chemical Respiratory Hypersensitivity." Toxicology Letters 86(1996): 89-92.
- Bickis, U., and K. Nakatsu. "A Single Skin Contact with Toluene Diisocyanate (TDI) Causes a One-Year Persistence of Airway Sensitization, Demonstrable in Vivo and in Vitro." (1996). Abstract of platform presentation No. 310 presented at the 1996 American Industrial Hygiene Conference and Exposition.
- Bickis, U. "Investigation of Dermally Induced Airway Hyperreactivity to Toluene Diisocyanate in Guinea Pigs." Ph.D. thesis, Department of Pharmacology and Toxicology, Queen’s University, Kingston, Canada, (1994).
- Karol, M. H., et al. "Dermal Contact With Toluene Diisocyanate (TDI) Produced Respiratory Tract Hypersensitivity in Guinea Pigs." Toxicol. Appl. Pharmacol 58(1981): 221-230.
- Rattray, N. J., et al. "Induction of Respiratory Hypersensitivity to Diphenylmethane-4,4’-Diisocyanate (MDI) in Guinea Pigs; Influence of route of exposure." Toxicology 88(1994): 15-30.
- Deschamps, F., et al. "Mechanisms of Occupational Asthma Induced by Isocyanate." Ann. Occup. Hyg. 42(1998): 33-36.
- Cole, K. C., et al. "Flexible Polyurethane Foam. I. FTIR Analysis of Residual Isocyanate." Applied Polymer Science 34(1987): 395-407.
- Chemical Sampling Information. OSHA. Presents, in concise form, data on a large number of chemical substances that may be encountered in industrial hygiene investigations. Basic reference for industrial hygienists engaged in OSHA field activity.
- Occupational Chemical Database. OSHA maintains this chemical database as a convenient reference for the occupational safety and health community. It compiles information from several government agencies and organizations. This database originally was developed by OSHA in cooperation with EPA.
For additional information, see OSHA's Sampling and Analysis Safety and Health Topics Page.
National Institute for Occupational Safety and Health (NIOSH)
- NIOSH Manual of Analytical Methods (NMAM). US Department of Health and Human Services (DHHS), National Institute for Occupational Safety and Health (NIOSH) Publication No. 2003-154, (2003). Provides individual analytical methods, listed by chemical name or method number.
- U.K. Health and Safety Executive Method 25/2
- The following are analysis methods for specific isocyanate compounds. It is often desirable to determine the amount of free isocyanate, not just the specific compound. Several methods have been suggested to accomplish this. However, all have had serious problems when applied to field sampling.
- Streicher, RP, et al. Investigation of the ability of MDHS method 25 to determine urethane-bound isocyanate groups. American Industrial Hygiene Association Journal. 1995;56(5):437-42.
- Key-Schwartz, RJ. Analytical problems encountered with NIOSH method 5521 for total isocyanates. American Industrial Hygiene Association Journal. 1995;56(5):474-9.
- Maitre, A., et al. Biological monitoring of occupational exposure to toluene diisocyanate. Int. Arch. Occup. Environ. Health. 1993;65:97-100.
- Documentation of the threshold limit values and biological exposure indices. American Conference for Government Industrial Hygienists (ACGIH). 1991;6:1581-9.
- Use of portable air compressors as a source of air supply for supplied air respirators. OSHA Hazard Information Bulletin (HIB), (1985, January 25). States that under current policy, supplied air respirators are not to be used in an atmosphere that is immediately dangerous to life or health (IDLH) unless the respirator is equipped with a self-contained air supply for escape.
- NIOSH Pocket Guide to Chemical Hazards. US Department of Health and Human Services (DHHS), National Institute for Occupational Safety and Health (NIOSH) Publication No. 2005-149, (2007, September). Provides a physical description, exposure limits, measurement method, personal protection and sanitation, first aid, respirator recommendations, exposure routes, symptoms, target organs, and cancer sites.
- Occupational Health Guidelines for Chemical Hazards. US Department of Health and Human Services (DHHS), National Institute for Occupational Safety and Health (NIOSH), (1981, January). Contains information on identification, physical and chemical properties, health hazards, exposure limits, exposure sources and control methods, monitoring, personal hygiene, storage, spills and leaks, and personal protective equipment.
- Health Hazard Evaluations. National Institute for Occupational Safety and Health (NIOSH). Performs Health Hazard Evaluations (HHE's) for a wide variety of industries that use isocyanates to determine whether any substance normally found in the workplace contains potentially toxic concentrations. NIOSH also provides specific control recommendations. To access the online database, follow the link and then search the site using the term "isocyanate." Some HHE's that focus on isocyanates are listed below.
- Isocyanate Exposures From Polyurethane Foam Packaging Operations, General Motors Corporation, Allison Transmission Division, Indianapolis, Indiana [1 MB PDF, 16 pages]. Report No. HETA 99-0065-2780, (1999, December).
- Isocyanate-Containing Compounds During Spray Painting Operations, Lockheed Martin Aeronautical Systems, Marietta, Georgia [2 MB PDF, 21 pages]. Report No. HETA 99-0122-2798, (2000, June).
- Worker Exposure To Methylene-bisphenyl-diisocyanate (MDI) From Foam Spraying Operations In an Adjacent Building, Twin City Fruit, F.L. Thorpe Co., Deadwood, South Dakota [1 MB PDF, 17 pages]. Report No. HETA 89-0278-2035, (1990, April).
- Isocyanates Used In Some Powder Coatings, Modern Materials Incorporated, Rochester, Indiana [3 MB PDF, 56 pages]. Report No. HETA 90-0174-2231, (1992, July).
- Possible Isocyanate and Polyamide Imide Resin Exposures Occurring During Brazing and Welding Operations, Square D Company, Oshkosh, Wisconsin [1 MB PDF, 23 pages]. Report No. HETA 94-0312-2512, (1995, June).
- A Summary of Health Hazard Evaluations: Issues Related to Occupational Exposure to Isocyanates, 1989 to 2002 [1 MB PDF, 42 pages]. Report No. HETA 99-0039, (1999, April). Presents some background information about isocyanate exposures, health effects, analytical methods, and general recommendations for most isocyanate-related HHE's. The major portion of this document presents the titles and summaries of the site visits related to isocyantes conducted between 1989 and 2002.
Related Safety and Health Topics Pages
- Isocyanates in Paints [193 KB PDF, 2 pages]. Workplace Safety and Health Division of the Manitoba Labour and Immigration Bulletin 143, (2008, December). Includes a short summary of hazards and protective measures for workers spraying isocyanate-containing paints.
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