Toluene Diisocyanates

2,6-diisocyanato-1-methyl-benzene (2,6 toluene diisocyanate)      
2,4-diisocyanato-1-methyl-benzene (2,4-toluene diisocyanate)
diisocyanatomethyl-benzene (mixed isomers of toluene diisocyanate)

What is it?

This group of three substances consists of two closely related manufactured chemicals and a mixture of the two that is used in large quantities by industry, mainly to manufacture other chemicals.

Where is it found and how is it used? 

A commercial mixture of 2,4- and 2,6-toluene diisocyanate is the most common form of this substance used by industry, although the pure 2,4- isomer form may sometimes be used.

The commercial mixture is mainly used to make polyurethane foam, which accounts for 80% to 90% of toluene diisocyanate in use. Flexible polyurethane foam is used extensively in mattresses, pillows, carpet underlay, household furniture, and automotive upholstery.  Rigid polyurethane foam panels are used for thermal insulation in housing, refrigerated trucks, rail cars and containers, refrigerators and freezers, and in pipe insulation.  Semi-flexible and semi-rigid polyurethane foam are used in automotive panels, padding and bumpers. Toluene diisocyanate is used to make castable urethanes for a variety of uses such as adhesives, sealants, automotive parts, shoe soles, wheels, pond liners, and blood bags. It is used in polyurethane-modified alkyd paints and coatings including automotive and marine paint, wood varnish, floor treatment, wire and powder coating, and in the production of coatings for textiles for durability and waterproofing and in the production of the fabric spandex. Toluene diisocyanate may also be used in nylon production.

What are its effects?  

More than one reputable international organization has classified these diisocyanate substances as possibly carcinogenic to humans. It does not persist in the environment, is not bioaccumulative, and is not considered toxic to aquatic organisms based on experimental and modelled data .

What are we doing?   

Based on the information obtained through the categorization process, this substance has been identified as a high priority for further action. As such, it has been included in the first batch of substances released under the Government of Canada's Challenge to industry and other stakeholders.

Under the Challenge, the Government of Canada will use existing legal tools and the regulatory process to obtain information from industry and other stakeholders on how they are managing this substance. New information will be reviewed by Government of Canada scientists to determine what further actions may be necessary to ensure that the health of Canadians and their environment are protected. If new information is not provided, the Government of Canada will nevertheless take action on a precautionary basis.  

For more information, see the technical substance profile.