Toluene Diisocyanates (TDI) - information sheet

Benzene, 2,4,-diisocyanato-1-methyl- (2,4-TDI)
CAS Registry Number 584-84-9

Benzene, 1,3,-diisocyanato-2-methyl-  (2,6-TDI)
CAS Registry Number 91-08-7

Benzene, 1,3,-diisocyanatomethyl-  (TDI mixed isomers)
CAS Registry Number 26471-62-5

Updated February 15, 2019:

The Final Screening Assessment for toluene diisocyanates (TDIs) was published on July 5, 2008 under the Challenge Initiative of the Chemicals Management Plan (CMP). The assessment is summarized in this information sheet (formerly public summary) and has not changed. The section in this information sheet entitled "Preventive actions and reducing risk" communicates updates in risk management activities, namely:

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  • The Government of Canada conducted a science-based evaluation, called a screening assessment, to address the potential for harm to Canadians and to the environment from toluene diisocyanates (TDIs).
  • Under the Canadian Environmental Protection Act, 1999 (CEPA 1999), the risk posed by a substance is determined by considering both its hazardous properties (its potential to cause adverse human health or ecological effects) and the amount of exposure there is to people and the environment. A substance may have hazardous properties; however, the risk to human health or to the environment may be low depending upon the level of exposure.
  • As a result of the screening assessment, TDIs were concluded to be harmful to human health, but not to the environment, at levels of exposure at the time of the assessment.

About these substances

  • This screening assessment focused on 3 substances referred to collectively as TDIs. The substances addressed were 2,4-TDI, 2,6-TDI, and TDI mixed isomers. They were assessed as part of Batch 1 of the Challenge Initiative of the CMP.
  • TDIs are industrial chemicals that are used to manufacture certain products.
  • At the time of the assessment, about 86% of TDIs were used in the manufacture of polyurethane foam in Canada. Polyurethane foam is used in household furniture and automotive upholstery, mattresses, pillows, packaging and carpet underlay.
  • TDIs may also be used in sealants, coatings, adhesives, some alkyd paints (automotive and marine paint), wood varnish, floor treatment, and wire and powder coating. TDIs had limited applications in food packaging and food processing, with no expected human exposure from food-related uses.

Human and ecological exposures

  • The assessment indicated that Canadians may be exposed to TDIs mainly through inhalation during the use of non-foam products available to consumers. In addition, exposures can be elevated near certain industrial facilities where TDIs are used.
  • Releases to the environment in Canada from industrial processes were mainly to air. Exposure of the environment to TDIs was considered to be low.
  • Current exposures may be different from the time the assessment was published.

Key health and ecological effects (hazard)

  • At the time of the assessment, the important or "critical" effects used for characterizing the risk to human health from TDIs were carcinogenicity (ability to cause cancer), and respiratory effects (breathing problems).
  • International agencies have also classified TDIs for carcinogenicity. For example, the International Agency for Research on Cancer (IARC) classified TDIs as "possibly carcinogenic to humans" (Group 2B). TDIs have also been classified as a dermal and respiratory sensitizer. Sensitization can result in breathing problems or effects on the skin.
  • TDIs were considered to have low potential for ecological effects.

Risk assessment outcomes

  • Based upon a comparison of levels to which Canadians can be exposed to TDIs and levels associated with health effects, it was determined that TDIs may pose a risk to human health.
  • TDIs are not expected to remain in the environment for a long period of time or accumulate in organisms. Considering all the information presented, it was determined that TDIs are unlikely to cause ecological harm in Canada.
  • The Government of Canada published the Final Screening Assessment for Toluene Diisocyanate (TDI) on July 5, 2008.

Screening assessment conclusions

  • As a result of the screening assessment, the Government concluded that TDIs are harmful to human health at levels of exposure current at the time of the assessment.
  • The Government also concluded that TDIs are not entering the environment at levels that are harmful to the environment.

Preventive actions and reducing risk

Related information

  • TDIs may be found in certain products available to consumers. Canadians should follow any safety warnings and directions on product labels and dispose of products responsibly.
  • Canadians who may be exposed to TDIs in the workplace should consult with their employer and an occupational health and safety (OHS) representative about safe handling practices, applicable laws, and requirements under OHS legislation and the Workplace Hazardous Materials Information System (WHMIS).

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