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Request for information about Toluene Diisocyanates

August 2013
NIOSH Docket Number 262, CDC-2013-0011

The National Institute for Occupational Safety and Health (NIOSH) of the Centers for Disease Control and Prevention (CDC) intends to evaluate the scientific data on toluene diisocyanates (TDI) and other TDI-based isocyanate products to develop a Criteria Document to establish an updated Recommended Exposure Limit (REL) for toluene diisocyanate. The current REL for 2,4-toluene diisocyanate is the lowest feasible concentration with no ceiling due to the potential carcinogenicity of TDI. The new criteria document will update information regarding use of TDI, exposures, and to provide a quantitative risk assessment with a REL. The Occupational Safety and Health Administration's (OSHA) permissible exposure limit and the American Conference of Governmental Industrial Hygienist (ACGIH) threshold limit value (TLM) for TDI is 0.005 parts per million (ppm) with a ceiling of 0.02 ppm.

Toluene diisocyanates are colorless to pale yellow liquids or solids with a sharp, pungent odor. TDI is one of the most commonly used diisocyanates. The most common formulation of TDI is a mixture of two isomers: 80% 2,4-TDI and 20% 2,6-TDI. Occupational exposure occurs during production and use of diisocyanates, such as the mixing and foaming processes in the polyurethane foam industry, and during spray adhesive application in the automobile and furniture industries. TDI is an irritant to the eyes, skin, and the gastrointestinal and respiratory tracts. Workers exposed to TDI may also be sensitized, such that they might be subject to asthma attacks.

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Background Information

Request for Information on Toluene Diisocyanates [PDF - 197 KB]

CIB 53: Toluene diisocyanate (TDI) and Toluenediamine (TDA): evidence of carcinogenicity [PDF - 3,689 KB]

Preventing asthma and death from diisocyanate exposure DHHS [PDF - 599 KB]