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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.
Reference
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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