Cyclohexanamine, 4,4'-methylenebis[2,6-dimethyl-

Endpoint summary

Additional information

Ames-Test

According to the results of the present study, the test substance did not lead to a relevant increase in the number of revertant colonies either without S9 mix or after adding a metabolizing system in several experiments carried out independently of each other (standard plate test and preincubation assay). Besides, the results of the negative as well as the positive controls performed in parallel corroborated the validity of this study, since the values fulfilled the acceptance criteria of this study. [BASF, 2010]

Micronucleus assay

According to the results of the present in vitro micronucleus assay, the test substance 4,4’-Diamino-3,3’,5,5’-tetramethyl-dicyclohexylmethane did not lead to a biologically relevant increase in the number of micronucleated cells either without S9 mix or after the addition of a metabolizing system in two experiments performed independently of each other. The frequencies of micronuclei after test substance treatment were close to the range of the concurrent vehicle control values at both exposure times and clearly within the range of our historical negative control data.

The number of micronucleated cells in the vehicle control groups were within our historical negative control data range and, thus, fulfilled the acceptance criteria of the study.

HPRT

The test item 4,4'-Diamino-3,3',5,5'-tetramethyl-dicyclohexylmethane was assessed for its potential to induce gene mutations at the HPRT locus using V79 cells of the Chinese hamster.

Relevant cytotoxic effects indicated by a relative cloning efficiency I or cell density below 50% in both parallel cultures occurred in the first experiment at 336.0 μg/mL and above without and at 336.0 μg/mL with metabolic activation (4 hours treatment). In the second experiment cytotoxic effects as described above were noted at 84.0 μg/mL without metabolic activation (24 hours treatment) and at 336.0 μg/mL and above with metabolic activation. The recommended cytotoxic range of approximately 10-20% relative cloning efficiency I or relative cell density was covered with and without metabolic activation.

No relevant and reproducible increase in mutant colony numbers/106 cells was observed in the main experiments up to the maximum concentration. Isolated increases of the induction factor exceeding the induction factor of three times the mutation frequency of the corresponding solvent control were observed in the first culture of the second experiment without metabolic activation at 5.3, 42.0, and 84.0 μg/mL (24.3, 25.3, and 19.1 mutant colonies per 106 cells). However, the isolated increases of the mutation frequency described above were judged as biologically irrelevant as the absolute values of the mutation frequency remained within the historical range of solvent controls (2.6 - 40.3 mutant colonies per 106 cells).

Short description of key information:
4,4’-Diamino-3,3’,5,5’-tetramethyl-dicyclohexylmethane was not mutagenic in the Ames test (E. coli and S. typhimurium), HPRT and in vitro MNT either with or without a metabolizing system.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

Based on the results of the Ames tests, the in vitro micronucleus test, and the HPRT assay, 4,4’-Diamino-3,3’,5,5’-tetramethyl-dicyclohexylmethane does not need to be classified according to Directive 67/548/EEC and according to the EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008.