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
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.
search results on Isocyanates
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 ApplicationsNIOSH 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.
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)
This Alert summarizes seven case reports of disease and deaths
following occupational exposure to diisocyanates, and provides
recommendations for prevention of exposures.
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
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
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.
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
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 PDF only 114 KB (26 pages)
- Method for Isocyanates Total (MAP) (No. 5525) PDF only 242 KB (17 pages)
- Method for Isocyanates (No. 5522) PDF only 36 KB (6 pages)
- Method for Monomeric Isocyanates (No. 5521) 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,
PDF only 984 KB (25 pages)
- HHE Report, HETA-2004-0038-2966, US Roofing Contractors,
PDF only 1 MB (21 pages)
- HHE Report, HETA-99-0196-2860, Future Aviation, Inc.,
PDF only 412 KB (28 pages)
- HHE Report, HETA-99-0122-2798, Lockheed Martin Aeronautical
Systems, Marietta, Georgia
PDF only 276 KB (21 pages)
- HHE Report HETA 97-0084-2669, Woodward Governor Company,
Fort Collins, Colorado
PDF only 416 KB (50 pages)
- HHE Report HETA 97-0138-2677, Shindoni, Inc., Tesuque, New
PDF only 322 KB (20 pages)
- HHE Report HETA-94-0265-2703, J. L. Long Middle School,
PDF only 272 KB (32 pages)
- HHE Report No. HETA-94-0312-2512, Square D Company,
PDF only 216 KB (23 pages)
- HHE Report No. HETA-94-0124-2470, Whirlpool, Corp.,
PDF only 336 KB (35 pages)
Provides information on applicable standards, examples of hazards and
possible solutions, sampling and analysis methods, more...
Department of Health Services - Isocyanates
Provides Health and Safety information for workers who
may be exposed to isocyanates.
Preventing Asthma and Death When Applying Spray-on Truck-bed Liners
This Washington Department of Labor and Industries Alert provides
information on the hazards associated with exposure to isocyanates
while spraying on truck bed linings.
Project SENSOR News - Fall 2003: Fatal Work-Related
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.
Environmental Protection Agency - Automotive Refinishing Partnership
Provides resources about health and environmental
concerns associated with refinishing activities, including information
on Diisocyanates and other chemicals.
Health Clinics for Ontario Workers, Inc. - Isocyanates Web Site
Provides information on isocyanates and how they are
used, health effects, monitoring, controls, more...
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.
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).
External Link: http://www.isofacts.org/
Safety Limited - Isocyanates
Provides descriptions of common isocyanates, health
effects, exposure routes, controls and practices, more...
Contains a description of the Institute and its activities, as well as
information on Institute scientific studies.
External Link: http://www.diisocyanates.org
Alliance for Polyurethanes IndustryEnvironmental 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.
Walk the Talk ProgramEuropean 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.