2,6-xylidine

Carcinogenicity

Description of key information

Carcinogenicity in vivo
Initial indications of a carcinogenic effect of 2,6-xylidine are available from a feeding study - however, in this case exposure via the inhalation path was also possible

Justification for classification or non-classification

Based on these results, 2,6-xylidine is classified as a mutagenic carcinogen according to the EU and GHS criteria Cat. 3 and needs to be adequately labelled. In addition, the test substance is listed in the CLP Regulation No 1272-2008 on classification, labelling and packaging of substances and mixtures and classified as carcinogen cat.2.

Additional information

In a report of the National Toxicology Program (Montgomery et al., 1982) the carcinogenic effect following feeding with 2,6-xylidine was observed. The incidence of papillary adenomas and adenocarcinomas of the nasal cavity and for subcutaneous fibromas in male and female rats at the highest dose (3 g/kg feed) was significantly increased. This dose also led to a significant increase in the incidence of hepatomas in the female animals. 2 males and 2 females respectively of this dosage group showed rhabdomyosarcomas in the nasal cavities, a neoplastic lesion, which had not previously been described at this position in this species of rat. The high incidence of tumours in the nasal cavity in this study is remarkable for a feeding test. This could be an organotropic effect, as is known from some nitrosamines. This possibility is supported by the fact that 2,6-xylidine binds to the DNA of the nasal cavity mucous membrane after i.p. administration (Short et al., 1989b). Another possible explanation for the higher incidence of tumours in the nasal cavity is that the 2,6-xylidine in the feed is evaporated as a gas. In an examination by Jameson et al. (1984) it was shown that 7.2 % per day of the test substance is lost, and of this 70 – 80 % through evaporation from the feed. This effect leads to a not inconsiderable exposure via the inhalation path, which could explain the nasal cavity tumours found in this and the following studies. In a summary of 86 two year carcinogenicity studies the authors report on a feeding test, in which male and female CD1 rats were given 0, 300, 1000 or 3000 mg 2,6-xylidine per kg feed (no further information). Both the male-and-female animals showed papillary adenomas and adenocarcinomas in the nasal mucous membrane (Haseman et al., 1984).

Carcinogenicity: via oral route (target organ): respiratory: nose