A critical review of the literature on nitrobenzene toxicity.

This literature review encompassing information available through 1980 and limited coverage in 1981, emphasizes results useful in assessing the potential toxic effects of nitrobenzene to man. Nitrobenzene exposure in man or experimental animals is most often associated with methemoglobinemia. Histopathologic changes also are observed in the hemato-lymphoreticular system, central nervous system, and liver. In addition, lesions have been reported in adrenals and testes. No information was found on carcinogenic or teratogenic potential, fertility, or reproductive effects of nitrobenzene. Results from Ames Salmonella assay are negative but test procedures are questionable; metabolites give positive results. Metabolism of nitrobenzene involves either oxidation or reduction yielding p-aminophenol and p-nitrophenol, and other reduced intermediates. From the foregoing, several aspects of nitrobenzene toxicity have been identified which warrant further study. Recommendations are made for chronic and subchronic exposure of test animals via inhalation to assess various toxicological endpoints. In addition, the relationship of nitrobenzene metabolism to its toxicity needs to be established. Genotoxic effects of nitrobenzene also need study.