Fatty acids, C18 unsaturated, trimers, hydrogenated

Endpoint summary

Additional information

Justification for grouping of substances and read-across

There are no data available on the cytogenicity or the potential for induction of gene mutations in mammalian cells of Fatty acids, C18-unsaturated, trimers, hydrogenated. In order to fulfil the standard information requirements set out in Annex VIII, Section 8.4.2 and 8.4.3, in accordance with Annex XI, Section 1.5 of Regulation (EC) No 1907/2006, read-across from a structurally similar substance is 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 physicochemical, toxicological and ecotoxicological properties may be predicted from data for reference substance(s) by interpolation to other substances on the basis of structural similarity, Fatty acids, C18-unsatd., dimers (CAS 61788-89-4) is selected as reference substances for assessment of cytogenicity and gene mutations in mammalian cells.

The read-across is based on structural similarity as a result of common origin and production process line. Shortly, the source and target substances are derived from catalytically di- and trimerised long-chain fatty acids; dimers and trimers are separated by distillation and unsaturated alkyl chains are hydrogenated as specifically required. A detailed analogue approach justification is provided in the technical dossier (see IUCLID Section 13).

Overview of genetic toxicity

	Target substance	Source substance
CAS No.	1373883-45-4	61788-89-4
Chemical name	Fatty acids, C18-unsaturated, trimers, hydrogenated	Fatty acids, C18-unsatd., dimers
In vitro gene mutation in bacteria	Experimental result: Not mutagenic	Experimental result: Not mutagenic
In vitro cytogenicity in mammalian cells	RA: CAS 61788-89-4	Experimental result: Not clastogenic
In vitro gene mutation in mammalian cells	RA: CAS 61788-89-4	Experimental result: Not mutagenic

 

In vitro gene mutation in bacteria

A reverse mutation assay (Ames test) was conducted with Fatty acids, C18-unsaturated, trimers, hydrogenated according to OECD Guideline 471 and in compliance with GLP (Thompson, 2013). The tester strains Salmonella typhimurium TA 1535, TA 1537, TA 98, TA 100 and Escherichia coli WPS2 uvrA were treated with the test item (diluted in DMSO) in two independent experiments (plate incorporation and pre-incubation method, respectively) at 50, 150, 500, 1500 and 5000 µg/plate, in triplicate, both with and without metabolic activation (S9 mix). Appropriate untreated, vehicle and positive controls were included.

The negative and positive control plates gave counts of revertant colonies within the expected normal ranges. The test item caused no visible reduction in the growth of the bacterial background lawn at any dose level. A test item precipitate (greasy in appearance) was noted at and above 1500 µg/plate, without preventing the scoring of revertant colonies.

No toxicologically significant increases in the frequency of revertant colonies were recorded for any of the bacterial strains at any concentration either with or without metabolic activation. A small, statistically significant increase in TA 100 revertant colony frequency was observed in the absence of S9 mix at 5000 µg/plate in the pre-incubation experiment. This increase was considered to be of no biological relevance because there was no evidence of a dose-response relationship or reproducibility. Furthermore, the individual revertant colony counts at 5000 µg/plate were within the in-house historical untreated/vehicle control range for the tester strain and the fold increase was only 1.4 times the concurrent vehicle control.

Under the conditions of this test, the test item was considered to be non-mutagenic in bacteria.

In vitro cytogenicity

CAS 61788-89-4

The ability of Fatty acids, C18-unsaturated, dimers to induce chromosome aberrations in vitro was assessed in a study performed according to OECD Guideline 473 and in compliance with GLP (Akhurst, 1993). Lymphocytes from human male blood donors were stimulated to divide by phytohaemagglutinin treatment and exposed to the test substance both in the presence and absence of a metabolic activation system (S9 mix). A vehicle (DMSO) and positive controls (ethylmethanesulphonate and cyclophosphamide, without and with metabolic activation, respectively) were included in the study. Based on solubility in the test medium, 300 µg/mL was the highest concentration tested. Two experiments were conducted.

In the first experiment, cells were exposed to the test substance at concentrations from 0.6 to 300 µg/mL for 18 h without metabolic activation or 3 h with metabolic activation and 15 h recovery period. Precipitation was observed at the highest concentration and resulted in a decrease in mitotic index to 65% of the control value without metabolic activation. Three concentrations (75, 150 and 300 µg/mL) were selected for metaphase analysis.

In the second experiment, cells were exposed to concentrations between 37.5 and 300 µg/mL as above (18 h harvest) and additionally at 9.4-300 µg/mL for 32 h without metabolic activation and 3 h with metabolic activation with 29 h recovery (32 h harvest). In all cases, slight to heavy precipitation was observed at 150 and 300 µg/mL, respectively. The mitotic index was markedly reduced only at the 32 h harvest without metabolic activation (63 and 3% of control value at 150 and 300 µg/mL, respectively). Cells treated with 75, 150 and 300 µg/mL for the 18 h harvest and with 150 (-S9 mix) and 300 (+S9 mix) for the 32 h harvest were selected for metaphase analysis.

In both experiments, there were no statistically significant increases in the frequency of cells with chromosome aberrations, either with or without metabolic activation. Solvent control values were within the historical range of the testing laboratory and the positive controls yielded the expected results.

It was therefore concluded that the test substance showed no evidence of clastogenic activity under the test conditions of the study.

In vitro gene mutation in mammalian cells

CAS 61788-89-4

Fatty acids, C18-unsaturated, dimers were tested in an in vitro mammalian cell mutation assay according to OECD Guideline 476 and GLP (Adams et al., 1993). Mouse lymphoma L5178Y cells were treated with DMSO (vehicle control) or the test substance at 25-300 µg/mL for 3 h with and without metabolic activation (S9 mix) in two independent experiments. Ethylmethanesulphonate (-S9 mix) and 20-methylcholanthrene (+S9 mix) were included as positive controls. The highest concentration was selected based on solubility in the test medium.

Cytotoxicity was observed both in the absence and (more clearly) presence of S9 mix (at 300 and at and above 150 µg/mL, respectively).

In the presence S9 mix, no statistically significant increases in mutant frequency were observed in any of the two experiments performed. A statistically significant increase in mutant frequency was observed at 250 µg/mL without metabolic activation in the second experiment. This increase was small (1.7-fold of the control value) and it was not considered to be biologically significant. The untreated and solvent control values were within the historical range and the positive control substances expectedly induced significant increases in mutant frequency.

It was thus concluded that the test substance was not mutagenic in this in vitro study.

Conclusions for genetic toxicity

The substance Fatty acids, C18-unsaturated, trimers, hydrogenated has been tested in a reverse mutation assay (Ames test). Under the conditions of the study, the substance was considered to be not mutagenic in bacteria.

There is no information available on in vitro cytogenicity and gene mutations in mammalian cells. Therefore, in order to fulfil the standard information requirements set out in Annex VIII, Section 8.4.2 and 8.4.3, in accordance with Annex XI, Section 1.5 of Regulation (EC) No 1907/2006, read-across from a structurally similar substance is conducted.

The available chromosome aberration study in human lymphocytes and gene mutation study in mouse lymphoma L5178Y cells conducted with Fatty acids, C18-unsatd., dimers (CAS 61788-89-4) indicate that the substance is not clastogenic and not mutagenic in mammalian cells.

Based on the available data, the substance Fatty acids, C18-unsaturated, trimers, hydrogenated is considered to be not mutagenic and not clastogenic in vitro.

Justification for selection of genetic toxicity endpoint
Hazard assessment is conducted using substance specific data and by means of read-across from a structural analogue. 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 substance and overall quality assessment (refer to the endpoint discussion for further details).

Short description of key information:
Based on substance specific data and read-across from Fatty acids, C18-unsaturated, dimers (CAS No. 61788-89-4):
Gene mutation in bacteria (Ames test): negative in S. typhimurium TA 1535, TA 1537, TA 98 and TA 100 and E. coli WP2 uvr A with and without metabolic activation (OECD 471/EU Method B.13/14, GLP)
Cytogenicity: negative in cultured peripheral human lymphocytes with and without metabolic activation (OECD 473/EU Method B.10, GLP)
Gene mutation in mammalian cells: negative in Mouse lymphoma L5178Y cells without metabolic activation (OECD 476/EU Method B.17, GLP)

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

Based on substance specific data and read-across from a structurally similar substance following an analogue approach, the available data on the genetic toxicity of the substance do not meet the classification criteria according to Regulation (EC) No 1272/2008 or Directive 67/548/EEC, and are therefore conclusive but not sufficient for classification.