2-phenylpropionaldehyde-dimethyl acetal

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Ames test: Negative (OECD TG 471, GLP)

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Additional information

The test substance was evaluated in a bacterial reverse mutation assay performed according to OECD 471 and following GLP using Salmonella typhimurium strains TA98, TA100, TA 1535 and TA1537 and Escherichia coli strain WP2 uvrA both in the presence and absence of an exogenous metabolic activation system (S9 -mix). In the first experiment, test substance concentrations of 1.5, 5, 15, 50, 150, 500, 1500 and 5000 μg/plate were assessed using the plate incorporation assay in triplicate.A small, statistical response was noted for TA1535 in Experiment 1,therefore the experiment was repeated using test concentrations of 50, 150, 500, 1000, 1500, 3000 and 5000 μg/plate.There were no statistically significant increases noted to TA1535 in Experiment 2, therefore, a third, confirmatory experiment was performed using thepreincubation method at test concentrations of 15, 50, 150, 500, 1500 and 5000 μg/plate.The vehicle (dimethyl sulphoxide) control plates gave counts of revertant colonies within the normal range. All of the positive control chemicals used in the test induced marked increases in the frequency of revertant colonies, both with and without metabolic activation. Thus, the sensitivity of the assay and the efficacy of the S9-mix were validated. In the first and second mutation test, the test item induced no visible reduction in the bacterial background lawns of any tester strains. In experiment 3, weakened bacterial background lawns were noted at 5000 μg/plate to all of the tester strains in both the absence and presence of S9-mix. No test item precipitate was observed on any of the plates. There were no biologically relevant increases in the frequency of revertant colonies recorded for any of the bacterial strains, with any dose of the test item, either with or without metabolic activation (S9-mix) in Experiment 1. Small, statistically significant increases in TA100 revertant colony frequency were observed in the first mutation test at 500, 1500 and 5000 μg/plate in the absence of S9-mix. These increases were within the in-house historical vehicle/untreated control range for the strain and were, therefore considered of no biological relevance. Statistically significant increases in TA1535 revertant colony frequency were also observed in the first mutation test at 5000 μg/plate in the absence of S9-mix. Although these counts exceeded the in-house historical untreated/vehicle control range, the increases were still considered to be of no biological relevance because there was no evidence of a dose-response relationship and could not be reproduced in further experiments. In the second experiment, no biologically relevant increases in the frequency of revertant colonies were recorded for any of the bacterial strains, with any dose of the test item, either with or without metabolic activation. Statistically significant increases in TA100 revertant colony frequency were observed in the second mutation test at 5000 μg/plate in the absence of S9-mix, however this response was within the in-house historical vehicle/untreated control range for the strain and was, therefore considered of no biological relevance. In experiment 3, no significant increases in the frequency of revertant colonies were recorded for any of the bacterial strains, with any dose of the test item, either with or without metabolic activation. Although the increases noted for TA1535 in Experiment 1 were quite large (3.5 fold the concurrent vehicle control), they were considered to be of no biological relevance because they could not be reproduced in two further experiments (one of which contained intermediate test item concentration levels in an attempt to qualify the response). There were many different sized colonies noted at the statistically significant dose level (5000 μg/plate) and there may have been an issue with underlying contamination but it was considered that the results should be confirmed in further tests. Therefore, the test material was considered to be non-mutagenic under the conditions of this test.

Justification for classification or non-classification

Based on the results of the Ames test, the substance does not need to be classified for genotoxicity according to EU CLP (EC 1272/2008 and its amendments).