Diisopentyl ether

Endpoint summary

Additional information

In vitro genotoxicity

In vitro: Reverse mutation assay:

In a GLP compliant Ames test, performed according to OECD guideline 471, five Salmonella typhimurium strains (TA97a, TA98, TA100, TA102 and TA1535) were used to test the mutagenic potential of diisopentyl ether both with and without metabolic activation. Diisopentyl ether was tested at concentrations up to and including 5000 μg/plate. Results from positive and negative controls were well within historical control ranges, indicating that the test conditions were adequate and that the metabolic activation system functioned properly. The first experiment (plate incorporation assay) showed no significant increase in the number of revertant colonies, both in the presence and in absence of metabolic activation. The first experiment is therefore considered negative for mutagenicity. These results were, however, not confirmed in the second independent repeat (pre-incubation method), in which increased numbers of revertant colonies were observed in two bacterial strains (TA98 and TA1535), however without a dose response relationship. The results of the second experiment were confirmed in a third experiment (pre-incubation method) and therefore it was concluded that diisopentyl ether showed mutagenic effects towards Salmonella typhimurium, strains TA98 and TA1535 under the conditions of the test.

In vitro: Micronucleus test:

In a GLP compliant In vitro Mammalian Cell Micronucleus Test, performed according to OECD guideline 487 the test substance diisopentyl ether was examined for its potential to induce micronuclei in cultured binucleated human lymphocytes in both the absence and presence of a metabolic activation system (S9 -mix). Human lymphocytes were tested in two pre-experiments and one main experiment at concentrations up to and including 1589 μg/mL. Ethanol was used as solvent. Adequate negative and positive controls were included in the assays. The scoring of micronuclei from the pre-experiments was not regarded for evaluation, as precipitation, haemolysis and high cytotoxicity was observed at several concentrations and cytostasis was below 55% in the remaining concentrations. In the main study dose-related increases in micronucleated cells were observed at concentrations 250 and 300 μg/mL (+S9) and at 32, 34 and 36 μg/mL the absence of S9. Therefore, the results of the study are considered to be positive. Under the experimental conditions of this in vitro study, diisopentyl ether is considered to have the potential to induce micronuclei.

As indicated in the REACH Regulation (Annex VIII), an in vivo mutagenicity test shall be considered in case of a positive result in any of the genotoxicity studies in Annex VII or VIII. In addition, in the REACH guidance (Chapter R.7A – Endpoint Specific Guidance) it is stated that an in vivo test should be initiated as soon as possible following a positive result in an in vitro mammalian cell mutagenicity test. Based on the positive results in the Ames test and the in-vitro MN test, it was decided to perform the in vivo micronucleus test with diisopentyl ether.

In vivo genotoxicity

In vivo: Micronucleus test:

A GLP-compliant erythrocyte micronucleus test was performed according OECD guideline 474. Four groups of 5 male animals were dosed via oral gavage with vehicle or with 2000, 1000 and 500 mg Diisopentyl ether per kg body weight. A positive control group (cyclophosphamide) was included. It was concluded that, under the conditions used in this study, diisopentyl ether did not induce chromosomal damage or damage to mitotic apparatus of the bone marrow target cells of male mice up to a dose of 2000 mg/kg.

Short description of key information:

The substance was tested both in vitro and in vivo. In vitro, positive results were observed in the Ames test (in strains TA98 and TA1535 both in presence and in absence of metabolic activation) and the MN test (micronucleus).

In vivo, as no increased micronucleated erythrocytes (clastogenicity) were observed, the substance is not considered clastogenic or aneugenic.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

Based on the available data, classification for mutagenicity is not needed according to EU Directive 67/584/EEC and EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008.