Dimethylcyclohex-3-ene-1-carbaldehyde

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Gene mutations in bacterial cells (Ames) test according to OECD TG 471: Negative

Gene mutations in mammalian cells (MLA) test according to OECD TG 476: Negative

Chromosome aberration test in mammalian cells according to OECD TG 473: Negative

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Additional information

Ames test:

The mutagenic activity of the test substance was evaluated in a study equivalent to OECD 471 and according to GLP principles. The test was performed according to the pre-incubation method, in the absence and presence of S9-mix. The dose levels were selected based on observed growth inhibition in all strains (156 µg/plate or above with S9-mix and 313 µg/plate or above without S9-mix). Adequate vehicle and positive controls were included. The substance did not induce a significant dose-related increase in the number of revertant colonies in each of the five tester strains (S. typhimurium TA100, TA1535, TA98, TA1537 and E. coli WP2uvrA), both in the absence and presence of metabolic activation. Based on the results of this study it is concluded that the test substance is not mutagenic in the bacterial reverse mutation assay.

 

MLA test:

In a mammalian cell gene mutation assay conducted according to OECD guideline 476 and GLP, mouse lymphoma L5178Y cells cultured in vitro were exposed to the test substance. In the definitive mutation assay, the concentrations ranged from 1.0 to 130 µg/mL without activation and from 5.0 to 250 µg/mL with S-9 activation. The incubation time was 4 hours. After the two-day expression period, cultures were selected for cloning based on their RSG. Cultures treated with 30, 40, 50, 60, 70, 80, 90, 100, 110, 120 µg/mL without activation and 60, 80, 100, 120, 140, 150, 160, 170, 180, 200 µg/mL with activation were cloned. The Relative Total Growth (RTG) for the cloned cultures ranged from 2% to 50% for cultures treated without activation and from 10% to 67% for cultures treated in conjunction with exogenous activation. In the confirmatory mutation assay with an incubation time of 24 hours, cultures were treated with concentrations ranging from 0.1 to 90 µg/mL in absence of S-9 activation. The cultures treated with 0.5, 0.75, 1, 2.5, 5, 10, 20, 30, 40, 50 µg/mL were cloned for mutant selection. The RTG for the cloned cultures ranged from 1% to 90%. Positive control chemicals induced appropriate responses. All of the cloned cultures treated with the test substance in both the definitive and confirmatory mutation assays had mutant frequencies that were similar to that of their corresponding solvent control cultures. Therefore, under the test conditions, the test substance is negative in the L5178Y TK+/ mouse lymphoma mutagenesis assay.

 

Chromosomal aberration test:

In an in vitro chromosome aberration test performed according to OECD guideline 473 and in compliance with GLP, Chinese Hamster Ovary (CHO) cells were exposed to the test substance with and without exogenous metabolic activation (phenobarbital/ß-naphthoflavone-induced rat liver S9-mix). In the range finding test, the test article was evaluated in a concentration range of 0.5- 5000.0 µg/mL both with and without metabolic activation. In the main test, chromosome aberrations were scored in de definitive assay (3 hours exposure) from the cells treated with the concentrations of 50, 100 and 125 µg/mL without activation and 100, 200, 400 µg/mL with activation based on the cytotoxicity data. In the confirmatory assay (18 hours exposure) 50, 100 and 150 µg/mL concentrations were investigated without metabolic activation. With activation, the percentage of endoreduplicated cells was lower than SITEK historical data of DMSO. Both the solvent and positive controls in the assays fulfilled the requirements of a valid test. The percentage of polyploidy was in the normal range (0-5.0%) in both definitive and confirmatory assays. The percentage of endoreduplicated cells was 4.0% in the definitive assay without activation which was higher than the normal range (0-1.0%) acquired from published data, however this increase was not confirmed in the confirmatory Assay. The results indicate that the test substance did not induce a statistically significant increase in the percentage of cells with aberrations both with and without metabolic activation when compared to the solvent controls, at the concentrations tested. Therefore, under the conditions of this test and according to the criteria set for evaluating the test results, the test substance was negative both with and without metabolic activation in the CHO Chromosome Aberration Assay.

Justification for classification or non-classification

Based on the negative results of the Ames test, the mouse lymphoma assay and the chromosome aberration test, classification for genotoxicity is not warranted in accordance with to EU CLP (EC No. 1272/2008 and its amendments).