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Notices to Readers NIOSH Current Intelligence Bulletin 53: Toluene Diisocyanate (TDI) and Toluenediamine (TDA); Evidence of Carcinogenicity

CDC's National Institute for Occupational Safety and Health (NIOSH) has released NIOSH Current Intelligence Bulletin 53: Toluene Diisocyanate (TDI) and Toluenediamine (TDA); Evidence of Carcinogenicity (1).* Current Intelligence Bulletins (CIBs) provide new data or update existing information about chemical substances, physical agents, or safety hazards found in the workplace.

CIB 53 presents recent information about the potential carcinogenicity of toluene diisocyanate (TDI) and toluenediamine (TDA) to humans. Recent studies of chronic effects in animals indicate that cancer is associated with exposure to commercial-grade TDI (an 80:20 mixture of 2,4- and 2,6-TDI) and 2,4-TDA, a hydrolysis product of TDI. This bulletin describes the results and implications of these animal studies, describes the known health effects of TDI and TDA in humans, and suggests guidelines for minimizing occupational exposures.

No case reports or epidemiologic studies are available regarding TDI or TDA carcinogenicity in humans, but the animal data on carcinogenicity provides sufficient evidence to warrant concern about occupational exposure to TDI and TDA. The tumorigenic responses observed in both rats and mice treated with TDI or TDA meet the criteria of the Occupational Safety and Health Administration's carcinogen policy for classifying a substance as a potential occupational carcinogen (29 CFR** 1990). Although the carcinogenic potential of the other TDI and TDA isomers has not been adequately determined, exposure to all TDI and TDA isomers should be reduced. NIOSH therefore recommends that all the isomers of TDI and TDA be regarded as potential occupational carcinogens and that occupational exposures to TDI and TDA be limited to the lowest feasible concentrations. Reported by: Div of Standards Development and Technology Transfer, National Institute for Occupational Safety and Health, CDC.


  1. NIOSH. Current intelligence bulletin #53: toluene diisocyanate (TDI) and toluenediamine (TDA); evidence of carcinogenicity. Cincinnati: US Department of Health and Human Services, Public Health Service, CDC, 1990; DHHS publication no. (NIOSH)90-101.

    • Single copies are available without charge from the Publications Dissemination Section, Division of Standards Development and Technology Transfer, NIOSH, CDC, 4676 Columbia Parkway, Cincinnati, OH 45226; telephone (513) 533-8287. **Code of Federal Regulations.

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