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Carcinogenicity

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Description of key information

Negative in vitro and in vivo genotoxicity assays (for details see chapter 7.6.). 
Negative 2-year carcinogenicity experiment in rats.
Negative cell transformation assay

Key value for chemical safety assessment

Additional information

No indications of a mutagenic, clastogenic or aneugenic potential were identified in a variety of in vitro and in vivo genotoxicity assays (for details see chapter 7.6.).

In a 2-year carcinogenicity experiment in rats 30 animals per sex were fed with dose levels of 1 or 5% for 104 weeks. No treatment related increase in neoplastic (and non-neoplastic) lesions were reported (Hoechst AG, 1966).

Furthermore, in a 2-year chronic study in cats no apparent increase in mortality due to a significant tumor formation was observed (Hoechst AG, 1966).

The quality of study reporting and study performance of both sudies is not to current standards. Here both studies are reported for completness but their value for an assessment is limited.

 

In a cell transformation assay using C3H 10T-1/2 cells, concentrations up to 20000 µg/ml were tested in 11- and 38-day incubations following a 24 h exposure to trioxane (Celanese, 1981). No increase in the number of transformed colonies or transformed foci was noted at any dose level.

 

By means of a weight of evidence the clearly negative results in the available genetox assays, together with the cell transformation assay and the available information of a 2-year carcinogenicity experiment in rats provide an acceptable database for the evaluation of the carcinogenic potential of trioxane. No indications of a carcinogenic potential were described and therefore further chronic testing regarding carcinogenicity is not indicated from a scientific point of view and by means of animal welfare.

Justification for classification or non-classification