NTP Toxicology and Carcinogenesis Studies of Commercial Grade 2,4 (80%)- and 2,6 (20%)- Toluene Diisocyanate (CAS No. 26471-62-5) in F344/N Rats and B6C3F1 Mice (Gavage Studies).

Toluene diisocyanate (TDI) is commercially produced as an approximate 80:20 mixture of the 2,4- and 2,6-isomers. In 1980, 580,000 pounds of this chemical were produced in the United States, primarily for use in the manufacture of flexible polyurethane foams. These foam elastomers are found in furniture and automobile cushions, carpet underlays, pillow filling, mattresses, insulation, shoes, purses, and toys. TDI is also used to produce polyurethane coatings for lacquers and wood finishes. Groups of 50 female F344/N rats and 50 B6C3F1 mice were administered commercial grade toluene diisocyanate (80% 2,4- and 20% 2,6-) in corn oil by gavage at doses of 60 or 120 mg/kg body weight, 5 days per week for 105 or 106 weeks. Groups of 50 male F344/N rats received 30 or 60 mg/kg and groups of 50 male B6C3F1 mice received 120 or 240 mg/kg on the same schedule. Dosage analyses of toluene diisocyanate indicated that the chemical had reacted in the corn oil vehicle, resulting in actual gavage concentrations 77% to 90% of theoretical values. Groups of 50 rats and 50 mice of each sex received corn oil only and served as vehicle controls. Survival in all groups of dosed rats in the 2-year studies were shorter (P