Reaction mass of lithium 3-hydroxy-2,2,4-trimethylpentanoate and lithium isobutyrate and sodium 3-hydroxy-2,2,4-trimethylpentanoate and sodium isobutyrate

Endpoint summary

Additional information

In an GLP/OECD Test Guideline 471 study to determine the mutagenic potential of the Reaction mass of lithium 3-hydroxy-2,2,4-trimethylpentanoate and lithium isobutyrate and sodium 3-hydroxy-2,2,4-trimethylpentanoate and sodium isobutyrate in bacterial cells in vitro, negative results were obtained using histidine-requiring auxotroph strains of Salmonella typhimurium (TA 100, TA 98, TA 1537 and TA 1535) and using the tryptophan-requiring strain of Escherichia coli ,WP2 uvrA, in the presence and in the absence of metabolic activation (Valiczko, 2013). The substance did not induce gene mutations by base pair changes or frameshifts in the genome of the strains used and had no mutagenic activity in the bacterial test strains used in the study. On this basis, the Reaction mass of lithium 3-hydroxy-2,2,4-trimethylpentanoate and lithium isobutyrate and sodium 3-hydroxy-2,2,4-trimethylpentanoate and sodium isobutyrate is not genotoxic in bacterial cells in vitro.

The claustogenic potential of the substance in vitro was assessed in a chromosome aberration study conducted according to OECD Test Guideline 473 using Chinese hamster V79 lung cells (Hargitai, 2014a). In the study, three separate assays were carried out in which cells were treated with the test item at concentrations between 312.5 to 5000 μg/L with metabolic activation (in the presence of S9-mix) for 3 hours or without metabolic activation (in the absence of S9-mix) for 3 or for 20 hours. Treatment with the test item resulted in a statistically marginally significant repeatable, dose-dependent increase in the frequency of the cells with structural chromosome aberrations without gaps in the absence of a metabolic system. No increase in the aberration frequency was detected in the presence of metabolic activation system. It was concluded that the Reaction mass of lithium 3-hydroxy-2,2,4-trimethylpentanoate and lithium isobutyrate and sodium 3-hydroxy-2,2,4-trimethylpentanoate and sodium isobutyrate was considered to be claustogenic in the test system. 

The potential for the substance to cause genotoxic effects in the bone marrow erythrocytes of mice was assessed in a micronucleus test conducted according to OECD Test Guideline 474 (Hargitai, 2014b). In the study, groups of male mice were treated with the vehicle (distilled water) or the test item at 500, 1000 or 5000 mg/kg BW/day by oral gavage or the positive control item (cyclophosphamide dissolved in physiological saline) at 60 mg/kg bw administered by intraperitoneal injection. There was no treatment related effects on bodyweight, no mortalities or signs of systemic toxicity. Piloerection was seen in the high and mid dose groups. No biologically or statistically significant increases in the frequency of micronucleated polychromatic erythrocytes were seen in mice treated with the test item, compared to the negative (vehicle) control at any of the sampling time points. The positive control treatment caused a strong, clearly positive response demonstrating the sensitivity of the test system.

The Reaction mass of lithium 3-hydroxy-2,2,4-trimethylpentanoate and lithium isobutyrate and sodium 3-hydroxy-2,2,4-trimethylpentanoate and sodium isobutyrate did not induce micronuclei in the bone marrow erythrocytes of mice treated up to 2000 mg/kg bw/day. The substance was not found to have any genotoxic activity under the conditions of the study.

Justification for selection of genetic toxicity endpoint
Negative results were obtained in an Ames tests. The substance was found to be claustogenic to Chinese hamster cells in the absence of metabolic activation in an in vitro chromosome aberration assay. However, negative results were obtained in a mouse micronucleus test indicating that the substance does not have genotoxic potential in vivo.

Short description of key information:
No evidence of mutagenicity was seen for the Reaction mass of lithium 3-hydroxy-2,2,4-trimethylpentanoate and lithium isobutyrate and sodium 3-hydroxy-2,2,4-trimethylpentanoate and sodium isobutyrate in a bacterial reverse mutation assay (Ames test). The substance was found to be clastogenic to Chinese hamster cells in the absence of metabolic activation in an in vitro chromosome aberration assay but gave negative results in an in vivo micronucleus test conducted to assess the induction of micronuclei in the bone marrow erythrocytes of mice. The substance does not have genotoxic potential in vivo.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

The Reaction mass of lithium 3-hydroxy-2,2,4-trimethylpentanoate and lithium isobutyrate and sodium 3-hydroxy-2,2,4-trimethylpentanoate and sodium isobutyrate is not genotoxic in bacterial cells in vitro. While the substance was found to be claustogenic in mammalian cells in vitro in a chromosome aberration study, the substance gave negative results in an in vivo micronucleus test conducted to assess the induction of micronuclei in the bone marrow erythrocytes of mice. Based on these findings, the substance does not meet the criteria for classification for genotoxicity according to Directive 67/548/EEC or Regulation 1272/2008/EC.