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Key value for chemical safety assessment

Additional information

The genetic toxicity of B-TTEGME was studied by testing B-TTEGMe and by read-across with data from various test materials, including Brake Fluid DOT 4 Super, Brake Fluid DOT 4 and B-TEGME. Similarity with B-TTEGME was based on a common functional group, common precursors an/or likelihood of common breakdown products and a common constituent, as also described in a separated justification document in Section 13.

The potential bacterial mutagenic effect of B-TTEGME was determined in various studies according to GLP and the OECD test guideline No. 471. All studies were considered of equal and high quality. The first study was based on B-TTEGME, which was therefore considered as key study (Shell, 2009); the two other studies were tested with B-TEGME (Clariant, 2007; BASF, 1989). In all studies, there was no mutagenicity up to the limit dose of 5000 µg/plate and two independent study parts took place (plate incorporation and preincubation method). Test systems were the Salmonnella thyphimurium strains TA 1537, TA 98, TA100 and TA 1535 (uvrB) and Escherichia coli WP2 (uvrA) strains with and without the metabolic system S9, respectively. Positive and negative controls were included in each study. Mutagenic and cytotoxic effects were absent.

A key study forchromosome aberration potential of brake fluid with 38% B-TTEGME, (of which ca. 45% was B-TEGME, coresponding with 17% B-TEGME in the tested brake fluid) was studied in vitro in Chinese Hamster Ovary (CHO) cells (Shell, 1992d). This study was conducted according to OECD 473 and GLP standards, and was therefore considered to be relevant, adequate and reliable. Cells were treated for either 3 hours in the presence of S9 mix or for 24 hours in the absence of S9 mix. Metaphase cells were analysed, demonstrating that the brake fluid and hence also B-TTEGME did not induce structural chromosome aberrations in cultured human lymphocytes both in the presence and in the absence of S9 mix, under the experimental conditions described.

Weight of evidence was also available from a chromosome aberration study with B-TEGME in human peripheral lymphocytes (Shell, 2010b). Cells were treated for 4 hours in the absence and presence of S9 with cell harvest after a 20-hour expression period. In Experiment 2, the 4-hour exposure with S9 was repeated; whilst in the absence S9 the exposure time was increased to 24 hours. The test material did not induce any statistically significant increases in the frequency of cells with aberrations, in either of two separate experiments. In conclusion, the test material was considered to be non-clastogenic to human lymphocytes in vitro.

Finally, gene mutation potential in mammalian cells was tested withB-TEGME to assess the potential mutagenicity on the hypoxanthine-guanine phosphoribosyl transferase (HPRT) locus of Chinese hamster ovary (CHO) cells (Shell, 2010c). The protocol used was designed to comply with GLP and the OECD Guidelines for Testing of Chemicals No. 476 'In Vitro Mammalian Cell Gene Mutation Tests', Commission Regulation (EC) No. 440/2008 and the United Kingdom Environmental Mutagen Society (Cole et al, 1990). The technique used is a plate assay using tissue culture flasks and 6-thioguanine (6­TG) as the selective agent. Chinese hamster ovary CHO-Kl cells were treated with the test material at six dose levels, in duplicate, together with vehicle (solvent) and positive controls. Cells were treated in a first experiment for 4 hours with and without S9. In Experiment 2, the 4-hour exposure with addition of S9 was repeated, whilst in the absence of S9 the exposure time was increased to 24 hours.The test material demonstrated no significant increases in mutant frequency at any dose level, either with or without metabolic activation, in either the first or second experiment. The test material was considered to be non-mutagenic to CHO cells under the conditions of the test. Based upon the structural, physicochemical and toxicological relationship of B-TTEGME and B-TEGME, B-TTEGME is also considered to have no mutagenic potential in mammalian cells.

 


Short description of key information:
Both undiluted B-TTEGME and undiluted B-TEGME were negative in the bacterial reverse mutation (Ames) test. Both brake fluid with B-TTEGME/BTEGME and undiluted B-TEGME were negative in the chromosome aberration study. Finally, B-TEGME was negative in the HPRT gene mutation assay in mammalian cells. As both compounds have a similar structural, physicochemical and toxicological profile, B-TTEGME is also considered negative in the latter test. In conclusion there were no indications of genotoxicity.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

Since brake fluids with B-TTEGME and B-TEGME were negative for genotoxicity testing in the various assays, classification for genotoxicity is not warranted.