Toluene-2,4-diisocyanate

The background information page contains information and concepts that will be useful in understanding some of the issues surrounding the NPI. It is strongly recommended that you read this before reading the information presented below.

For an explanation of some of the terms used in this page, see the Glossary

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.

Physical and chemical properties *Physical properties:* 2,4-Toluene diisocyanate (TDI) is a clear to pale yellow liquid with a sharp pungent odour. Melting Point (°C) 12.5 - 13.5 Boiling Point (°C) 251 Flash Point (°C) 121; Specific Gravity: 1.225 Vapour Density: 6 *Chemical properties:* TDI reacts with water, releasing carbon dioxide. It reacts (sometimes violently) with acids, bases, and alcohols.
Common uses 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.
Sources of emissions Point sources Industrial emissions to air (especially companies producing the materials listed above) or spills. Diffuse sources, and point sources included in aggregated emissions data Emission to air (by outgassing) from products containing TDI. Natural sources There are no known or expected natural sources of TDI emissions. Mobile sources No significant mobile emission sources. Consumer products which may contain Toluene-2,4-diisocyanate Polyurethane coatings, cement sealers, polyurethane mastic sealants, and polyurethane cushions and pads. Very low emissions of TDI have been infrequently detected from cushions.
Health effects How might I be exposed to Toluene-2,4-diisocyanate? 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. By what pathways might Toluene-2,4-diisocyanate enter my 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. Relative health hazard On a health hazard spectrum of 0 - 3 Toluene-2,4-diisocyanate registers 1.7. A score of 3 represents a very high hazard to health, 2 represents a medium hazard and 1 is harmful to health. Factors that are taken into account to obtain this ranking include the extent of the material's toxic or poisonous nature and/or its lack of toxicity, and the evaluation of its tendency to cause, or not cause cancer and/or birth defects. It does not take into account exposure to the substance. Human exposure is reflected in the NPI rank given to this substance (see comparative data below). A substance that scores highly as a health hazard is arsenic at 2.3 and one of the lowest scores is ammonia at 1.0. Health guidelines Worksafe Australia lists the following exposure Standard: 0.02 mg per cubic metre (0.00002 grams per cubic metre), on a time weighted average basis (TWA) 0.07 mg per cubic metre (0.00007 grams per cubic metre), for short term exposures (STEL) Note that it would take a concentration 10 to 20 times the level of the exposure standard before it would be detected by its odour. See the Additional Information page for current health information. The Australian NOHSC National Exposure Standards Database link is probably the most useful source of information. Note that the emissions data in the NPI database is not directly comparable with these guidelines. What effect might Toluene-2,4-diisocyanate have on my health? 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'.
Environmental effects *Environmental Fate* TDI reacts quickly with water other photochemically produced materials and therefore most of it will be out of the atmosphere in under two days. Environmental Transport Since it quickly reacts with water it will not accumulate in the environment. Relative hazard to the environment On an environmental spectrum of 0 - 3 Toluene-2,4-diisocyanate registers 1. A score of 3 represents a very high hazard to the environment and 0 a negligible hazard. Factors that are taken into account to obtain this ranking include the extent of the material's toxic or poisonous nature and/or its lack of toxicity, and the measure of its ability to remain active in the environment and whether it accumulates in living organisms. It does not take into exposure to the substance. Environmental exposure is reflected in the NPI rank for this substance (see comparative data below). A substance that scores highly as an environmental hazard is oxides of nitrogen at 3.0 and one of the lower scores is carbon monoxide at 0.8. Environmental guidelines See the Additional Information page for current environmental guidelines. No national guidelines. What effect might Toluene-2,4-diisocyanate have on the environment? 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.
Comparative data NPI Rank Approximately 400 substances were considered for inclusion on the NPI reporting list. A risk ranking was given based on health and environmental hazard identification and human and environmental exposure to the substance. Some substances were grouped together at the same rank with 208 ranks in total. Toluene-2,4-diisocyanate was ranked as 34 out of the 208 ranks. Total hazard score (human health + environmental criteria) = 2.7.
Sources of information used in preparing this article 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. National Health and Medical Research Council (NHMRC) and Agriculture and Resource Management Council of Australia and New Zealand (ARMCANZ) (1996), Australian Drinking Water Guidelines. 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), Exposure Standard Isocyanates (February 1999) (accessed, March, 1999) Worksafe Australia (1996), Hazardous Substance, Toluene-2,4-diisocyanate (February 1999) (accessed, March, 1999)

National Substance Emission Report