For definition of Groups, see Preamble Evaluation.
Supplement 7: (1987) (p.192)
Chem. Abstr. Name: Benzene, 1,2-dichloro-
Chem. Abstr. name: Benzene, 1,4-dichloro-
A. Evidence for carcinogenicity to humans (inadequate for ortho- and para-dichlorobenzene)
One report of a series of five cases has suggested an association between leukaemia and exposure to dichlorobenzenes [ref: 1].
B. Evidence for carcinogenicity to animals (inadequate for ortho-dichlorobenzene; sufficient for para-dichlorobenzene)
ortho-Dichlorobenzene was tested in mice and rats by gastric intubation; no evidence of carcinogenicity was observed [ref: 2]. A study by inhalation in several species was considered inadequate [ref: 1].
para-Dichlorobenzene was tested in mice and rats by gastric intubation; it caused renal tubular-cell adenocarcinomas in male rats and hepatocellular carcinomas in male and female mice [ref: 3]. It was also tested in mice and rats by inhalation; no increase in the incidence of tumours was noted, but the duration of exposure was limited [ref: 4].
C. Other relevant data
No data were available on the genetic and related effects of ortho- or para-dichlorobenzene in humans. ortho-Dichlorobenzene was not mutagenic to fungi or bacteria. para-Dichlorobenzene was mutagenic to fungi but not to bacteria [ref: 5].
para-Dichlorobenzene is possibly carcinogenic to humans (Group 2B).
ortho-Dichlorobenzene is not classifiable as to its carcinogenicity to humans (Group 3).
For definition of the italicized terms, see Preamble Evaluation.
Subsequent evaluation: Vol. 73 (1999)
Also see previous evaluations: Vol. 7 (1974); Vol. 29 (1982)
1. IARC Monographs, 29, 213-238, 1982
2. National Toxicology Programme (1985) Toxicology and Carcinogenesis
Studies of 1,2-Dichlorobenzene (o-Dichlorobenzene) (CAS No.
3. National Toxicology Program (1987) Toxicology and Carcinogenesis
Studies of 1,4-Dichlorobenzene (CAS No.
4. Loeser, E. & Litchfield, M.H. (1983) Review of recent toxicology studies on p-dichlorobenzene. Food chem. Toxicol., 21, 825-832
5. IARC Monographs, Suppl. 6, 222-225, 1987
Synonyms for ortho-Dichlorobenzene
See Also: Toxicological Abbreviations