3,4-dimethylbenzaldehyde

Endpoint summary

Additional information

Ames test:

In a GLP compliant bacterial mutagenicity assay (Ames plate incorporation method), performed according to OECD 471, using four Salmonella typhimurium strains (TA 1535, TA 1537, TA 98, and TA 100) and one E. Coli WP2uvrA strain, the test substance was evaluated in the presence and absence of rat liver derived metabolic activation system (S9-mix) (Safepharm Laboratories Ltd 2006). The dose range for the range-finding test was determined in a preliminary toxicity assay and was 15 to 5000 µg/plate. The experiment was repeated on a separate day using an amended dose range of 50 to 5000 µg/plate, fresh cultures of the bacterial strains and fresh test material formulations. Experiments were performed in triplicate.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 or without metabolic activation. Thus, the sensitivity of the assay and the efficacy of the S9-mix were validated.The test material caused a visible reduction in the growth of the bacterial background lawn to all of the tester strains at 5000 µg/plate both in the presence and absence of S9. No test material precipitate was observed on the plates at any of the doses tested in either the presence or absence of S9-mix. No significant increases in the frequency of revertant colonies were recorded for any of the bacterial strains, with any dose of the test material, either with or without metabolic activation. In conclusion, the test material was considered to be non-mutagenic under the conditions of this test.

 

Chromosome aberration test

In a GLP-compliant chromosome aberration test, tested according to OECD guideline 473, Chinese Hamster Lung (CHL/IU) cells were exposed to the test substance with and without metabolic activation (S9 -mix) (Safepharm Laboratories Ltd 2007).The study consisted of a Cell Growth Inhibition Test and two separate experiments. Except in the Cell Growth Inhibition Test, duplicate cultures of Chinese Hamster Lung (CHL) cells that had been treated with the test material in either the presence or absence of metabolic activation, were evaluated for induction of chromosome aberrations. Duplicate vehicle and positive controls were included in parallel in both experiments.Four exposure conditions were used: In Experiment 1 the exposures were 6(18)-hour both with and without metabolic activation; Experiment 2 included a 24-hour continuous exposure in the absence of S9 and a repeat of the 6(18)-hour with-S9 exposure group. The dose levels used were selected on the basis of molecular weight, solubility and the results of the Cell Growth Inhibition Test. The dose ranges for the 6(18)-hour exposures in Experiment 1 with and without S9 were 20.97 to 503.25 µg/ml and 20.97 to 335.5 µg/ml respectively. In Experiment 2 the dose range was 1.31 to 41.94 µg/ml for the 24 hours exposure group and 20.97 to 503.25 µg/ml for the with S9 exposure group. The vehicle (solvent) controls had frequencies of cells with aberrations within the range expected for the CHL cell line. All of the positive control materials induced highly significant increases in the frequency of cells with aberrations indicating the satisfactory performance of the test and of the activity of the metabolising system. The test material did not induce any statistically significant increases in the frequency of cells with aberrations in any of the exposure groups. The dose levels of the test material were shown to be toxic to CHL cells in vitro and optimal levels of toxicity were achieved in all exposure groups. In conclusion, the test material was considered to be non-clastogenic to CHL cells in vitro.

Short description of key information:
The test substance is considered to be not mutagenic in the in vitro chromosomal aberration test and Ames test.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

Based on the available genotoxicity studies, the test substance does not need to be classified for genotoxicity according to the Directive 67/548/EEC and according to the EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008.