TDI is used to manufacture polyurethane products. These are found in the form of coatings, sprays, insulation materials, polyurethane coated fabrics, and the largest application, foam cushioning.
Substance name: Toluene-2,4-diisocyanate
CASR number: 584-84-9
Molecular formula: C9H6N2O2
Synonyms: TDI, Toluene diisocyanate, 2,4 Diisocyanatotoluene, Isocyanic Acid, Methylphenylene Ester, 2,4-Diisocyanatotoluene, 2,4-Tolylene diisocyanate, cresorcinol diisocyanate, 4-methy-1,3-phenylene diisocyanate, toluene 2,4-diisocyanate.
2,4-Toluene diisocyanate (TDI) is a clear to pale yellow liquid with a sharp pungent odour.
Melting Point: 12.5 - 13.5°C
Boiling Point: 251°C
Flash Point: 121°C
Specific Gravity: 1.225
Vapour Density: 6
TDI reacts with water, releasing carbon dioxide. It reacts (sometimes violently) with acids, bases, and alcohols.
The National Pollutant Inventory (NPI) holds data for all sources of Toluene-2,4-diisocyanate in Australia.
TDI can burn the eyes and skin, it is toxic from both short term exposures and long term exposures. Single large inhaled doses can cause severe irritation of the respiratory, gastrointestinal, and central nervous systems. High levels can cause build up of fluids in the lungs, which could lead to death. Exposure can cause lung allergy, after which future low level exposures can trigger shortness of breath. Long term exposures (Chronic) have resulted in significant decreases in lung function in workers, asthma like reactions, and effects on the liver, blood and kidneys. The International Agency for Research on Cancer (IARC) has classified toluene 2,4-diisocyanate as a 'possible human carcinogen'.
Entering the body
TDI can be breathed into the body, if there has been a commercial discharge or a spill, or the misuse of consumer products containing TDI.
Exposure to TDI can occur in workplaces manufacturing TDI or using TDI in production or in the environment following releases to the air. Contamination to a consumer can occur when people mis-use certain polyurethane coatings, sealers, polyurethane foam kits, or sealants. Skin contact is a possible route of exposure, also from working with the product or misusing consumer products containing TDI.
Workplace exposure standards
Safe Work Australia sets the workplace exposure standards for airborne contaminants. There are no workplace exposure standards for toluene-2,4-diisocyanate.
Workplace exposure standards are only appropriate for use in workplaces and are not limited to any specific industry or operation. Make sure you understand how to interpret the standards before you use them.
Drinking water guidelines
There is no guideline for toluene-2,4-diisocyanate in the Australian Drinking Water Guidelines.
TDI has slight acute (short term) toxicity to aquatic life and high acute toxicity to birds. There is not sufficient data to predict or evaluate the long term effects of TDI and plants and animals.
Entering the environment
Since it quickly reacts with water it will not accumulate in the environment.
Where it ends up
TDI reacts quickly with water other photochemically produced materials and therefore most of it will be out of the atmosphere in under two days.
No national guidelines.
Sources of emissions
Industrial emissions to air (especially companies producing the materials listed above) or spills.
Diffuse sources, and industry sources included in diffuse emissions data
Emission to air (by outgassing) from products containing TDI.
There are no known or expected natural sources of TDI emissions.
No significant mobile emission sources.
Polyurethane coatings, cement sealers, polyurethane mastic sealants, and polyurethane cushions and pads. Very low emissions of TDI have been infrequently detected from cushions.
Sources used in preparing this information
- Australian and New Zealand Environment and Conservation Council (ANZECC) (1992), Australian Water Quality Guidelines for Fresh and Marine Waters.
- CalEPA Air Resources Board Toxic Air Contaminant Summary (1997) (accessed, March, 1999)
- ChemFinder WebServer Project 2,4-toluene diisocyanate (1995) (accessed, March, 1999)
- Cornell University Environmental Health and Safety, Toluene Diisocyanate 80-20 (April 1998) (accessed, March, 1999)
- Environmental Defense Fund Toluene-2,4-Diisocyanate (1999) (accessed, March, 1999)
- Meagher, D (1991), The Macmillan Dictionary of The Australian Environment, Macmillan Education Australia Pty Ltd.
- National Environment Protection Council (1998), National Environment Protection Measure for the National Pollutant Inventory (accessed, March, 1999)
- National Environment Protection Council (1998b), National Environment Protection Measure for Ambient Air Quality.
- New Jersey Department of Health, Right to Know Program (1986), TRIFacts (accessed, March, 1999)
- NTP Chemical Repository, Radian Corporation, 2,4-TOLUENE DIISOCYANATE (AUGUST 29, 1991) (accessed, March, 1999)
- Richardson, M (1992), Dictionary of Substances and their Effects, Royal Society of Chemistry, Clays Ltd, England.
- Sittig, M (1991), Handbook of Toxic and Hazardous Chemicals and Carcinogens, 3rd edition, Noyes Publications, USA.
- Technical Advisory Panel (1999), Final Report to the National Environment Protection Council.
- US Department of Health and Human Services (1990), NIOSH Pocket Guide to Chemical Hazards, Publication No. 90-117.
- US Environmental Protection Agency, Office of Air Quality Planning and Standards (1994), TOLUENE 2,4-DIISOCYANATE (accessed, March, 1999)
- Worksafe Australia (1996), Hazardous Substance, Toluene-2,4-diisocyanate (February 1999) (accessed, March, 1999)
- Safe Work Australia, Workplace exposure standards for airborne contaminants, accessed March 2019.
- National Health and Medical Research Council (NHMRC), Australian Drinking Water Guidelines (2011) - Updated October 2017, accessed May 2018.