Diisodecyl azelate

Endpoint summary

Additional information

Justification for grouping of substances and read-across

There are only limited data available on the genetic toxicity of diisodecyl azelate (CAS 28472-97-1). In order to fulfil the standard information requirements set out in Annex VII and VIII, 8.4, in accordance with Annex XI, 1.5, of Regulation (EC) No 1907/2006, read-across from structurally related substances was conducted.

In accordance with Article 13 (1) of Regulation (EC) No 1907/2006, "information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI are met.” In particular for human toxicity, information shall be generated whenever possible by means other than vertebrate animal tests, which includes the use of information from structurally related substances (grouping or read-across).

Having regard to the general rules for grouping of substances and read-across approach laid down in Annex XI, Item 1.5, of Regulation (EC) No 1907/2006 whereby substances may be predicted as similar provided that their physicochemical, toxicological and ecotoxicological properties are likely to be similar or follow a regular pattern as a result of structural similarity.

Overview of genetic toxicity

CAS	Chemical name	Molecular weight (range)	Genetic toxicity (mutagenicity) in vitro, bacteria	Genetic toxicity (cytogenicity) in vitro, mammalian cells	Genetic toxicity (mutagenicity) in vitro, mammalian cells	Genetic toxicity in vivo
28472-97-1 (a)	Diisodecyl azelate	468.75	RA: CAS 103-24-2	RA: CAS 103-24-2	Experimental result: not mutagenic	--
103-24-2	Bis(2-ethylhexyl) azelate	412.65	Experimental result: not mutagenic	Experimental result: not clastogenic	--	--

(a) The substance subject to registration is indicated in bold font.

(b) Reference (read-across) substances are indicated in normal font. Lack of data for a given endpoint is indicated by “--“.

The above mentioned substances are considered to be similar on the basis of the structural similar properties and/or activities. The available endpoint information is used to predict the same endpoints for diisodecyl azelate (CAS 28472-97-1). A detailed analogue approach justification is provided in the technical dossier (see IUCLID Section 13).

 

Discussion

Gene mutation in bacteria in vitro

Diester of azelaic acid

CAS 103-24-2

The potential mutagenicity of bis(2-ethylhexyl) azelate (CAS 103-24-2) was tested in a bacterial gene mutation assay (Ames test) according to OECD 471 and in compliance with GLP (Miwa, 2004). Based on the results of a preliminary cytotoxicity experiment, the Salmonella typhimurium strains TA 98, TA 100, TA 1535 and TA 1537 and Escherichia coli WP2 uvrA were treated with the test substance at concentrations of 312.5, 625, 1250, 2500 and 5000 µg/plate using the plate incorporation assay. The test was performed in two independent experiments, both with and without metabolic activation system (S9-mix). No cytotoxicity was observed in the two experiments up to the limit concentration of 5000 µg/plate. Colourless oil drop-like and oil membrane-like precipitations were observed on the surface of agar at all test concentrations. The mean number of revertant colonies was not increased at any test concentration compared to control. The positive controls included showed the expected results.

Under the conditions of this experiment, bis(2-ethylhexyl) azelate did not induce mutations in the bacterial gene mutation assay in the selected strains of S. typhimurium (TA 98, TA 100, TA 1535 and TA 1537) and in E. coli WP2 uvrA in the presence and absence of metabolic activation.

 

Cytogenicity in vitro

Diester of azelaic acid

CAS 103-24-2

The clastogenic potential of bis(2-ethylhexyl) azelate (CAS 103-24-2) was assessed in an in vitro mammalian chromosome aberration test in Chinese hamster lung (CHL/IU) cells according to OECD guideline 473 and under GLP conditions (Miwa, 2004). In a preliminary cytotoxicity test, 50% growth inhibition was observed after 6 h short-term treatment with the test substance at concentrations of 1859.0 µg/mL with S9 mix and at 1555.5 µg/mL without S9 mix. After continuous treatment for 24 h, cell growth was inhibited by 50% at 534.2 µg/mL without S9 mix. Based on these results, concentrations ranging from 150 to 2400 µg/mL (with and without S9 mix) and 37.5 to 600 µg/mL (without S9 mix) were selected for chromosome analysis after 6 and 24 h treatment in the main study, respectively. No increase in the number of cells with chromosomal aberrations was observed compared to controls in any of the experiments performed. The test substance was cytotoxic at ≥ 600 µg/mL after 6 h short-term treatment and at ≥ 300 µg/mL after 24 h continuous treatment. Visible precipitation of the test substance was observed at concentrations ≥ 1200 µg/mL, but did not interfere with chromosomal analysis. The positive controls included during short-term and continuous exposure showed the expected results and thus verified the sensitivity of the assay.

Under the conditions of this experiment, bis(2-ethylhexyl) azelate was considered not to be clastogenic in Chinese hamster lung (CHL/IU) cells in the presence or absence of metabolic activation.

 

Gene mutation in mammalian cells in vitro

An in vitro mammalian cell gene mutation assay was performed with diisodecyl azelate (CAS No. 28472-97-1) according to OECD guideline 476 (Verspeek, 2010). Mouse lymphoma L5178Y were treated with the test substance diluted in ethanol at concentrations of 0.03, 0.1, 0.3, 1, 3, 10, 33 and 100 µg/mL in cell culture medium with and without S9 mix. Due to solubility of the test substance no higher concentrations had been tested. After treatment the cells were incubated in selective medium with 5 µg/mL trifluorothymidine (TFT) to determine the mutation frequency. No cytotoxicity was observed in range finding tests or the main mutation experiment. The mutation frequency of the treated cultures was in range of historical control data and did not increase at the various concentrations compared to the negative control. Therefore diisodecyl azelate (CAS No. 28472-97-1) did not induce gene mutations in the mouse lymphoma cell line L5178Y at the given test conditions.

 

Conclusions for genetic toxicity

The available data on diisodecyl azelate (CAS 28472-97-1) and the structurally related substance bis(2-ethylhexyl) azelate (CAS 103-24-2) showed that the results of all in vitro genetic toxicity studies performed in bacteria and mammalian cells with and without metabolic activation were negative.

 

 

Justification for selection of genetic toxicity endpoint
Hazard assessment is conducted by means of read-across from structural analogues. No study was selected, since 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:
Diisodecyl azelate (CAS 28472-97-1) did not induce gene mutations in an in vitro mammalian cell gene mutation test in mouse lymphoma cells.
The read across substances Bis(2-ethylhexyl) azelate (CAS 103-24-2) showed no genotoxic effects, neither in an Ames test nor in a chromosome aberration test.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

Based on substance-specific data and read-across from the structurally similar substance, the available data on genetic toxicity 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.