3,5,5-trimethylhexyl 3,5,5-trimethylhexanoate

Endpoint summary

Additional information

Justification for read-across

There are limited data available on the genetic toxicity of 3,5,5-trimethylhexyl 3,5,5-trimethylhexanoate (CAS 59219-71-5). The assessment was therefore partly based on studies conducted with analogue substances as part of a read-across approach, which is in accordance with Regulation (EC) No. 1907/2006, Annex XI, 1.5. For each specific endpoint the source substance(s) structurally closest to the target substance is/are chosen for read-across, with due regard to the requirements of adequacy and reliability of the available data. Structural similarities and similarities in properties and/or activities of the source and target substance are the basis of read-across. A detailed justification for the analogue read-across approach is provided in the technical dossier (see IUCLID Section 13) and within Chapter 5.1 of the CSR.

Genetic toxicity (mutagenicity) in bacteria in vitro

CAS 59219-71-5

The potential mutagenicity of 3,5,5-trimethylhexyl 3,5,5 -trimethylhexanoate was assessed in a bacterial reverse mutation assay (Ames test) performed according to OECD guideline 471 and under GLP conditions (Sire, 2005). In two independent experiments, the Salmonella typhimurium strains TA 1535, TA 1537, TA 98, TA 100 and TA 102 were exposed to the test substance at concentrations of 312.5, 625, 1250, 2500 and 5000 µg/plate for a period of 48-72 h. The plate incorporation method was applied in the first experiment with and without metabolic activation, and in the second experiment without metabolic activation. The pre-incubation method was applied in the second experiment with metabolic activation. No cytotoxicity was observed up to and including the limit dose of 5000 µg/plate, with and without metabolic activation. A moderate to marked emulsion was observed in the Petri dishes at dose levels ≥ 625 µg/plate without metabolic activation, and at dose levels ≥ 1250 µg/plate with metabolic activation. No increase in the mean number of revertants was observed in any tester strain at any concentration tested. The positive controls were shown to be valid. Based on the results of this experiment, the test substance was considered to be non-mutagenic in the presence and absence of metabolic activation.

Genetic toxicity (clastogenicity) in mammalian cells in vitro

CAS 10233-13-3

An in vitro mammalian chromosome aberration test was performed with isopropyl laurate (CAS 10233-13-3) in primary human lymphocytes, according to OECD guideline 473 and under GLP conditions (Buskens, 2010). In the first experiment cells were exposed for 3 hours to test substance concentrations of 10, 33 and 100 µg/mL in ethanol with and without metabolic activation (S9-mix), with 24 and 48 hours expression time. In the second experiment cells were exposed for 24 hours to 66, 150 and 250 µg/mL followed by 24 hours expression time, and exposed for 48 hours to 3, 125 and 150 µg/mL followed by 48 hours expression time. The second experiment was performed without metabolic activation. 250 µg/mL was chosen as maximum dose as precipitation was observed at ≥ 100 µg/mL. The positive and negative controls were valid. 100 well-spread metaphase cells from each culture were evaluated. Some cytotoxicity was noted at the highest dose level without metabolic activation at the expression times of 24 and 48 hours (the mitotic index was 41% and 46%, respectively). No increase in the frequency of chromosome aberrations and polyploid cells was observed at any dose level. The test material was therefore non-clastogenic to human lymphocytes in vitro.

CAS 26399-02-0

The cytogenetic potential of 2-ethylhexyl oleate (CAS 26399-02-0) was assessed in an in vitro mammalian chromosome aberration test in primary human lymphocytes, performed according to OECD guideline 473 and under GLP conditions (Buskens, 2010). Duplicate cultures of human lymphocytes were evaluated for chromosome aberrations in the presence and absence of metabolic activation. In the first experiment, cells were incubated with test substance concentrations of 3, 10 and 33 µg/mL in ethanol for 3 hours with and without metabolic activation, with a 24 and 48 hour expression time. In the second experiment cells were incubated with 3, 10 and 33 µg/mL for 24 hours with 24 hours expression time and for 48 hours with 48 hours expression time, all without metabolic activation. 33 µg/mL was selected as the maximum dose due to the limited solubility of the test substance. The evaluation of 100 well-spread metaphase cells from each culture for structural chromosomal aberrations revealed no increase in the frequency of chromosome aberrations and polyploid cells at any dose level in comparison to the negative controls. The test material demonstrated only modest cytotoxicity. The vehicle and positive controls were shown to be valid. The test material was therefore non-clastogenic under the conditions of this study.

 

Genetic toxicity (mutagenicity) in mammalian cells in vitro

CAS 10233-13-3

An in vitro mammalian cell gene mutation assay was performed according to OECD guideline 476 under GLP conditions with isopropyl laurate (CAS 10233-13-3) in ethanol (Verspeek-Rip, 2010). The test substance was applied to mouse lymphoma L5178Y cells at concentrations up to and including 10 μg/mL, which was the precipitation level. The cells were treated for 3 and 24 hours without metabolic activation, for 3 hours with 8% (v/v) S9-mix, and for 3 hour with 12% (v/v) S9-mix, respectively. No cytotoxicity was observed. The positive and negative controls were valid. No significant increase in mutation frequency occurred. Therefore, isopropyl laurate was not mutagenic in the mouse lymphoma L5178Y test system under the experimental conditions in this study.

CAS 26399-02-0

An in vitro mammalian cell gene mutation assay was performed with 2-ethylhexyl oleate (CAS 26399-02-0) according to OECD guideline 476 and under GLP conditions (Verspeek-Rip, 2010). Mouse lymphoma L5178Y cells were exposed to the test substance in ethanol at concentrations up to 100 μg/mL, in the absence and presence of metabolic activation. In experiment 1, the exposure time was 3 hours with and without metabolic activation, while in experiment 2 the exposure time was 3 hours with metablic activation and 24 hours without metabolic activation. Precipitation was seen at concentrations of 100 µg/mL. The negative control group was valid and within the range of historical control data. The positive control group was shown to be valid. No significant increase in mutation frequency was observed.

Overall conclusion for genetic toxicity

There is one reliable study on the in vitro genetic toxicity of the target substance 3,5,5-trimethylhexyl 3,5,5-trimethylhexanoate available. Therefore, analogue read-across from source substances was applied fromin vitro studies on genetic toxicity in mammalian cells using 2 source substances. The results of the available in vitro studies on target and source substances were consistently negative.

Based on the available data and following the analogue approach, 3,5,5-trimethylhexyl 3,5,5-trimethylhexanoate is considered to be not mutagenic.

 

Justification for selection of genetic toxicity endpoint
Hazard assessment is conducted with a study performed using the target substance and by means of read-across from structural analogues. All available in vitro genetic toxicity studies were negative. All available studies are adequate and reliable based on the identified similarities in structure and intrinsic properties between source and target substances and overall quality assessment (refer to the endpoint discussion for further details).

Short description of key information:
Genetic toxicity in vitro:
Ames test (OECD 471): negative with and without metabolic activation in S. typhimurium TA 1535, TA 1537, TA 100, TA 98, TA 1538 and TA 102
Chromosome aberration (OECD 473): negative in primary human lymphocytes with and without metabolic activation
Gene mutation in mammalian cells (OECD 476): negative in L5178Y mouse lymphoma cells with and without metabolic activation

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

According to Article 13 of Regulation (EC) No. 1907/2006 "General Requirements for Generation of Information on Intrinsic Properties of substances", information on intrinsic properties of substances may be generated by means other than tests e.g. from information from structurally related substances (grouping or read-across), provided that conditions set out in Annex XI are met. Annex XI, "General rules for adaptation of this standard testing regime set out in Annexes VII to X” states that “substances whose physicochemical, toxicological and ecotoxicological properties are likely to be similar or follow a regular pattern as a result of structural similarity may be considered as a group, or ‘category’ of substances. This avoids the need to test every substance for every endpoint". Since the analogue concept is applied to 3,5,5-trimethylhexyl 3,5,5-trimethylhexanoate (CAS 59219-71-5), data will be generated from data for reference source substance(s) to avoid unnecessary animal testing. Additionally, once the analogue read-across concept is applied, substances will be classified and labelled on this basis.

Therefore, based on the available data on the target substance and on analogue read-across approach, the results on genetic toxicity for the target and source substances do not meet the classification criteria according to Regulation (EC) 1272/2008 or Directive 67/548/EEC, and are therefore conclusive but not sufficient for classification.