cis-2-tert-butylcyclohexan-1-ol

Endpoint summary

Description of key information

Skin sensitisation: Not a skin sensitiser based on testing in an OECD TG 442C and 422D.

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

DPRA:

The in chemico direct peptide reactivity assay (DPRA) was conducted to determine the sensitising potential of Verdol according to the OECD Guideline 422D in compliance with GLP. Based on a molecular weight of 156.26 g/mol a 100 mM stock solution was prepared in acetonitrile. The test item solutions were tested by incubating the samples with the peptides containing either cysteine or lysine for 24 ± 2 h at 25 ± 2.5 °C. Subsequently samples were analysed by HPLC. All test item solutions were freshly prepared immediately prior to use. For the 100 mM stock solution of the test item no turbidity or precipitation was observed when diluted with the cysteine peptide solution. After the 24 h ± 2 h incubation period but prior to the HPLC analysis samples were inspected for precipitation, turbidity or phase separation. No precipitation, turbidity or phase separation was observed for any of the samples. For the 100 mM stock solution of the test item turbidity was observed when diluted with the lysine peptide solution. After the 24 h ± 2 h incubation period but prior to the HPLC analysis samples were inspected for precipitation, turbidity or phase separation. Phase separation was observed for the samples of the test item (including the co-elution control). Samples were not centrifuged prior to the HPLC analysis. Phase separation in the lysine experiment was observed. Therefore, the given peak areas and corresponding lysine peptide values can only be considered as an estimation of the peptide depletion and cannot be used for evaluation. Sensitising potential of the test item was predicted from the mean peptide depletion of the cysteine peptide by comparing the peptide concentration of the test item treated samples to the corresponding reference control C. The 100 mM stock solution of the test item showed minimal reactivity towards the synthetic peptide. The mean depletion of the cysteine peptide was ≤ 13.89% (0.93%). The 100 mM stock solution of the positive control (cinnamic aldehyde) showed high reactivity towards the synthetic peptides. The mean depletion of both peptides was 68.50%. The controls confirmed the validity of the study for both, the cysteine and lysine run. In this study under the given conditions the test item showed minimal reactivity towards the cysteine peptide.

KeratinoSens:

The in vitro KeratinoSens™ assay was conducted to determine the sensitizing potential of Verdol according to the OECD Guideline 422D in compliance with GLP. Based on a molecular weight of 156.26 g/mol a stock solution of 200 mM was prepared in DMSO. Based on the stock solution a set of twelve master solutions in 100% solvent was prepared by serial dilution using a constant dilution factor of 1:2. These master solutions were diluted 1:100 in cell culture medium and a stable suspension was formed. The following concentration range was tested in the assay: 2000, 1000, 500, 250, 125, 62.5, 31.25, 15.63, 7.81, 3.91, 1.95, 0.98 µM. Cells were incubated with the test item for 48 h at 37°C. After exposure cells were lysed and luciferase activity was assessed by luminescence measurement. In the first experiment, no statistically significant luciferase induction > 1.5 was found in the tested concentration range. Therefore, no EC_1.5 value could be calculated. In the second experiment, no statistically significant luciferase induction > 1.5 was found in the tested concentration range. At a concentration of 15.63 µM a luciferase induction > 1.5 (1.78) was noted, but with no statistically significance. Furthermore, this increase was caused by one of the three replicates, which was clearly higher, but could not excluded a statistical outlier. Therefore, no EC_1.5 value could be calculated. No dose response for luciferase activity induction was observed for each individual run as well as for an overall luciferase activity induction. The controls confirmed the validity of the study.

In silico:

Further, Verdol was predicted to be a non-sensitizers by Derek Nexus. No alerts were found in protein binding (OASIS v1.1 and OECD) and protein binding alerts for skin sensitization when run in the OECD toolbox.

Conclusion:

Based on "2 out of 3" integrated testing strategy approach for Adverse Outcome Pathway for in vitro skin sensitization, Verdol is not considered to be a skin sensitizer.  

Justification for classification or non-classification

The substance is not a a skin sensitiser based on several in silico, in chemico and in vitro data and therefore does not need to be classified as a skin sensitiser according to EU CLP (EC No. 1272/2008 and its amendments).