Subchronic inhalation toxicity of nitromethane and 2-nitropropane.
Lewis-TR; Ulrich-CE; Busey-WM
J Environ Pathol Toxicol 1979 May/Jun; 2(5):233-249
Male rats and rabbits were exposed to 98 or 745 parts per million (ppm) of nitromethane (75525) (NM), or 27 or 207ppm of 2- nitropropane (79469) (2NP) for 7 hours per day, 5 days per week, for up to 24 weeks to evaluate the adequacy of the current OSHA standards of 100ppm for NM and 25ppm for 2NP. Physiologic, hematologic, serum biochemical, and histopathological evaluations of the exposed animals were compared with those of a control group. Exposure to NM resulted in no gross or microscopic tissue changes, although decreased body weights were noted in rats exposed for 8 weeks to 745ppm; rabbits exhibited increased thyroid weight and decreased serum thyroxin levels. Liver weights significantly were elevated in rats exposed to 207ppm 2NP for 1, 3, and 6 months. Liver neoplasms occurred in rats following 6 months of exposure to 207ppm 2NP. The authors conclude that 2NP is a potent carcinogen and should be handled as such in the workplace. The OSHA standard for NM appears to offer a satisfactory margin of safety for workers.
NIOSH-Contract; Contract-210-75-0039; Organic-solvents; Toxic-substances; Laboratory-animals; Hematology; Histopathology; Animal-studies; Dose-response; Exposure-limits; Serological-analysis; Regulations
Journal of Environmental Pathology and Toxicology. Toxicological and Carcinogenic Health Hazards in the Workplace: proceedings of the First Annual NIOSH Scientific Symposium, Cincinnati, Ohio, April 1978