1-Chloro-4-nitrobenzene Hazard Identification Executive Summary

1-Chloro-4-nitrobenzene is used as an intermediate in the synthesis of certain drugs, dyes, pesticides and other substances in commerce. It is not known to occur naturally. Administration of 1-chloro-4-nitrobenzene in feed to rats did not produce tumors, but administration in feed to mice produced vascular tumors (hemangiomas or hemangiosarcomas) in both males and females. It also produced hepatocellular tumors in male mice at the low dose but not at the high dose. 1-Chloro-4-nitrobenzene produced mutations in some, but not all, tests using the Salmonella typhimurium mutagenesis assay. In mammalian cells it produced sister chromatid exchanges and chromosomal aberrations in vitro and DNA strand breaks in vitro and in vivo. One of the metabolites of 1-chloro-4-nitrobenzene in rabbits, rats and humans is the known carcinogen 4-chloroaniline. There is evidence for the carcinogenicity of 1-chloro-4-nitrobenzene, based on observations of vascular tumors in male and female mice. Further evidence of carcinogenic potential is provided by observations of liver tumors at the lower of two doses in a study in male mice, chromosomal effects in vitro, DNA strand breaks in vitro and in vivo, and metabolism to a known carcinogen.