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NIOSH Safety and Health Topic:


Isocyanates are a family of highly reactive, low molecular weight chemicals. They are widely used in the manufacture of flexible and rigid foams, fibers, coatings such as paints and varnishes, and elastomers, and are increasingly used in the automobile industry, autobody repair, and building insulation materials. Spray-on polyurethane products containing isocyanates have been developed for a wide range of retail, commercial, and industrial uses to protect cement, wood, fiberglass, steel and aluminum, including protective coatings for truck beds, trailers, boats, foundations, and decks.

Isocyanates are powerful irritants to the mucous membranes of the eyes and gastrointestinal and respiratory tracts. Direct skin contact can also cause marked inflammation. Isocyanates can also sensitize workers, making them subject to severe asthma attacks if they are exposed again. Death from severe asthma in some sensitized subjects has been reported. Workers potentially exposed to isocyanates who experience persistent or recurring eye irritation, nasal congestion, dry or sore throat, cold-like symptoms, cough, shortness of breath, wheezing, or chest tightness should see a physician knowledgeable in work-related health problems.

Preventing exposure to isocyanates is a critical step in eliminating the health hazard. Engineering controls such as closed systems and ventilation should be the principal method for minimizing isocyanate exposure in the workplace. Other controls, such as worker isolation and personal protective clothing and equipment may also be necessary. Early recognition of sensitization and prompt and strict elimination of exposures is essential to reduce the risk of long-term or permanent respiratory problems for workers who have become sensitized.

The most widely used compounds are diisocyanates, which contain two isocyanate groups, and polyisocyanates, which are usually derived from diisocyanates and may contain several isocyanate groups. The most commonly used diisocyanates include methylenebis(phenyl isocyanate) (MDI), toluene diisocyanate (TDI), and hexamethylene diisocyanate (HDI). Other common diisocyanates include naphthalene diisocyanate (NDI), methylene bis-cyclohexylisocyanate (HMDI) (hydrogenated MDI), and isophorone diisocyanate (IPDI). Examples of widely used polyisocyanates include HDI biuret and HDI isocyanurate.

NIOSH Resources


NIOSHTIC-2 search results on Isocyanates
NIOSHTIC 2 LOGO is a searchable bibliographic database of occupational safety and health publications, documents, grant reports, and journal articles supported in whole or in part by NIOSH.


Got Everything Covered?
DHHS (NIOSH) Publication No. 2008-109 (January 2008)
This poster provides helpful tips on protecting workers from the hazards of isocyanate exposure during spray-on truck bedliner applications.

Preventing Asthma and Death from MDI Exposure During Spray-on Truck Bed Liner and Related Applications—NIOSH Alert
DHHS (NIOSH) Publication No. 2006-149 (September 2006)
This Alert summarizes four case reports: one death and several incidents of asthma or other respiratory disease following exposure to MDI during spray-on truck bed lining operations.

Issues Related to Occupational Exposure to Isocyanates, 1989 to 2002
DHHS (NIOSH) Publication No. 2004-116 (2004)
Collects the past 14 years of isocyanate-related Health Hazard Evaluations in a concise format for easy reference and examination.

Preventing Asthma and Death from Diisocyanate Exposure
DHHS (NIOSH) Publication No. 96-111 (1996)
Esta Pãgina en Español En Español
This Alert summarizes seven case reports of disease and deaths following occupational exposure to diisocyanates, and provides recommendations for prevention of exposures.

Current Intelligence Bulletin 53 - Toluene Diisocyanate (TDI) and Toluenediamine (TDA) - Evidence of Carcinogenicity
DHHS (NIOSH) Publication No. 90-101 (1989)
This bulletin describes the results and implications of animal studies that show cancer is associated with exposure to commercial-grade TDI. It also presents the known human health effects of TDI and TDA, and suggests guidelines for minimizing occupational exposures.

Criteria for a Recommended Standard: Occupational Exposure to Diisocyanates
DHHS (NIOSH) Publication No. 78-215 (1978)
Presents recommendations for the standard, biologic exposure information, environmental data,work practice recommendations, more...

NIOSH Pocket Guide to Chemical Hazards
DHHS (NIOSH) Publication No. 97-140
Exposure limits, Respirator Recommendations, First Aid, more...
The Pocket Guide is a source of general industrial hygiene information on several hundred chemicals/classes found in the work environment. Key data provided for each chemical/substance includes name (including synonyms/trade names), structure/formula, CAS/RTECS Numbers, DOT ID, conversion factors, exposure limits, IDLH, chemical and physical properties, measurement methods, personal protection, respirator recommendations, symptoms, and first aid.

Documentation for Immediately Dangerous to Life or Health Concentrations (IDLHs)
This publication documents the criteria and information sources that have been used by NIOSH to determine immediately dangerous to life or health concentrations (IDLHs).

Analytical Methods & Sampling

NIOSH Manual of Analytical Methods (NMAM)
DHHS (NIOSH) Publication No. 94-113 (1994)
NMAM is a collection of methods for sampling and analysis of contaminants in workplace air, and in the blood and urine of workers who are occupationally exposed.

  • Chapter K. Determination of Airborne Isocyanate Exposure this document in PDF PDF only 114 KB (26 pages)
  • Method for Isocyanates Total (MAP) (No. 5525) this document in PDF PDF only  242 KB (17 pages)
  • Method for Isocyanates (No. 5522) this document in PDF PDF only  36 KB (6 pages)
  • Method for Monomeric Isocyanates (No. 5521) this document in PDF PDF only  36 KB (6 pages)

Health Hazard Evaluations

NIOSH conducts Health Hazard Evaluations (HHEs) to find out whether there are health hazards to employees caused by exposures or conditions in the workplace.

Some recent HHE reports related to isocyanates have been listed below. For a comprehensive listing of HHE reports please search the HHE Database.

  • HHE Report, HETA-2004-0349-2970, Kewaunee Fabrications, LLC, Kewaunee, Wisconsin
    this document in PDF PDF only  984 KB (25 pages)

  • HHE Report, HETA-2004-0038-2966, US Roofing Contractors, Philadelphia, PA
    this document in PDF PDF only  1 MB (21 pages)

  • HHE Report, HETA-99-0196-2860, Future Aviation, Inc., Naples, Florida
    this document in PDF PDF only  412 KB (28 pages)

  • HHE Report, HETA-99-0122-2798, Lockheed Martin Aeronautical Systems, Marietta, Georgia
    this document in PDF PDF only  276 KB (21 pages)

  • HHE Report HETA 97-0084-2669, Woodward Governor Company, Fort Collins, Colorado
    this document in PDF PDF only  416 KB (50 pages)

  • HHE Report HETA 97-0138-2677, Shindoni, Inc., Tesuque, New Mexico
    this document in PDF PDF only  322 KB (20 pages)

  • HHE Report HETA-94-0265-2703, J. L. Long Middle School, Dallas, Texas
    this document in PDF PDF only  272 KB (32 pages)

  • HHE Report No. HETA-94-0312-2512, Square D Company, Oshkosh, Wisconsin
    this document in PDF PDF only  216 KB (23 pages)

  • HHE Report No. HETA-94-0124-2470, Whirlpool, Corp., Evansville, Indiana
    this document in PDF
     PDF only  336 KB (35 pages)

Other Resources

Governmental Resources

OSHA Isocyanates page
Provides information on applicable standards, examples of hazards and possible solutions, sampling and analysis methods, more...
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California Department of Health Services - Isocyanates
Provides Health and Safety information for workers who may be exposed to isocyanates.
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Guide to Preventing Asthma and Death When Applying Spray-on Truck-bed Liners
this document in PDF PDF only 
This Washington Department of Labor and Industries Alert provides information on the hazards associated with exposure to isocyanates while spraying on truck bed linings.
External Link:

Project SENSOR News - Fall 2003: Fatal Work-Related Asthma
this document in PDF PDF only 
This Michigan SENSOR Project newsletter details an asthma-related death of a worker shortly after spraying an isocyanate-based product used as a lining for truck beds.
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U.S. Environmental Protection Agency - Automotive Refinishing Partnership
Provides resources about health and environmental concerns associated with refinishing activities, including information on Diisocyanates and other chemicals.
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Occupational Health Clinics for Ontario Workers, Inc. - Isocyanates Web Site
Provides information on isocyanates and how they are used, health effects, monitoring, controls, more...
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Occupational Health and Safety Research Institute (Québec) - Guide for the Safe Use of Isocyanates
This guide provides employers and workers with an understanding of the risks associated with isocyanates.
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Non-Governmental Resources

IsoFacts: The American Chemistry Council Diisocyanates Panel Web Site
Provides health, safety, environmental and regulatory information on two important diisocyanates – toluene diisocyanate (TDI) and methylenebis(phenyl isocyanate) (MDI).
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Leavitt Safety Limited - Isocyanates
Provides descriptions of common isocyanates, health effects, exposure routes, controls and practices, more...
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International Isocyanate Institute
Contains a description of the Institute and its activities, as well as information on Institute scientific studies.
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Alliance for Polyurethanes Industry—Environmental Health and Safety
API promotes the sustainable growth of the polyurethane industry, in accordance with the principles of Responsible Care®, by identifying and managing issues that could impact the industry, in cooperation with user groups.
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Walk the Talk Program—European Diisocyanate & Polyol Producers Association (ISOPA)
Walk the Talk is a programme developed by the members of ISOPA with the aim of improving safety, health and environmental standards across the European polyurethanes industry. The “Walk the Talk” programme focuses on the behavioural safety of everyone involved in the industry through an ongoing process of information exchange and dialogue.
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worker spraying truck bed

Spray-on Truck-Bed Lining
Operations—NIOSH Alert

Guide to Preventing Asthma and Death When Applying Spray-on Truck-bed Liners
External Link:

Project SENSOR News Fall 2003: Fatal Work-Related Asthma
External Link:

Truck Bed Liners
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