Related Experiment Videos
Nitrobenzene carcinogenicity in animals and human hazard evaluation
1National Center for Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, Washington, DC 20460, USA. holder.james@epa.gov
Toxicology and Industrial Health
|September 16, 1999
Summary
Nitrobenzene (NB) exposure causes cancer in multiple rodent organs. Based on animal studies and metabolic data, NB is considered a probable human carcinogen via all exposure routes.
Area of Science:
- Toxicology
- Carcinogenesis
- Environmental Health
Background:
- Nitrobenzene (NB) is an industrial chemical with limited human cancer data.
- Animal studies indicate NB induces tumors in various organs across different rodent strains.
Purpose of the Study:
- To evaluate the carcinogenic potential of Nitrobenzene (NB) in animal models.
- To identify target organs and mechanisms of NB-induced toxicity.
Main Methods:
- Inhalation studies exposing three rodent strains (B6C3F1 mice, F344/N rats, Sprague-Dawley rats) to NB.
- Metabolic analysis of NB and its derivatives, including nitrosobenzene (NOB) and phenylhydroxylamine (PH).
- Assessment of biochemical effects such as methemoglobinemia and redox imbalances.
Main Results:
- NB induced malignant and benign tumors in multiple sites including mammary glands, lungs, thyroid, liver, and kidneys in rodents.
- Metabolic reduction of NB produced reactive intermediates like NOB and PH, forming a redox couple in red blood cells.
- Observed NB effects included hemosiderosis, methemoglobinemia, anemia, and redox imbalances.
Conclusions:
- Nitrobenzene (NB) is a multi-site rodent carcinogen.
- Metabolic activation and redox cycling are likely mechanisms of NB carcinogenicity.
- NB is classified as a probable human carcinogen due to structural similarities with known carcinogens and positive animal data.