Dioctadecyl ether

Endpoint summary

Additional information

Dioctadecyl ether was tested in a reverse mutation GLP-compliant assay using Salmonella typhimurium strains TA 1535, TA 1537, TA 98 and TA 100, and Escherichia coli strains WP2pKM101 and WP2 uvrA pKM 101. In the first test, concentrations of 1 to 500 µg/plate were tested in the absence and presence of metabolic activation using the plate incorporation assay. In the second test, concentrations of 1.5, 5, 15, 50, 150 µg/plate were tested in the absence (plate incorporation test) and presence (preincubation test) of metabolic activation. Under the conditions of this test, dioctadecyl ether was not cytotoxic and not mutagenic in any of the tested strains.

The homolog dioctylether dissolved in acetone was assessed for its potential to induce structural chromosome aberrations in V79 cells of the Chinese hamster in-vitro in two independent experiments according to OECD guideline 473. The following study design was performed:

 

without S9-mix				with S9-mix
	exp. I	exp. II		exp. I	exp. II
Exposure period	4 h	18 h	28 h	4 h	4 h
Recovery	14 h	-	-	14 h	24 h
Preparation interval	18 h	18 h	28 h	18 h	28 h

 

In each experimental group two parallel cultures were set up. Per culture at least 100 metaphase cells were scored for structural chromosome aberrations, except for the positive control in experiment II (without S9, interval 28 h) where only 50 metaphase cells were scored. The highest applied concentration in the pre‑test on toxicity (2500 µg/ml; approx. 10 mM) was chosen with regard to the molecular weight of the test item with respect to the current OECD Guideline 473. Due to strong toxicity in the absence of S9 mix a second range finding pre-test was performed. Test item concentrations between 0.2 and 20 µg/ml were applied in the absence of S9 mix only. Dose selection for the cytogenetic experiments was performed considering the toxicity data and the occurrence of precipitation.In both independent experiments, no biologically relevant increase in the number of cells carrying structural chromosomal aberrations was observed after treatment. No increase in the frequencies of polyploid metaphases was found after treatment as compared to the frequencies of the controls.In conclusion, it can be stated that in the study described and under the experimental conditions reported, the test substance did not induce structural chromosome aberrations as determined by the chromosome aberration test in V79 cells (Chinese hamster cell line) in-vitro.

The homolog dioctylether was assayed in a gene mutation assay in cultured mammalian cells (L5178Y TK+/-) both in the presence and absence of metabolic activation by a liver post-mitochondrial fraction (S9 mix) from Aroclor 1254-induced rats. The test was carried out employing 2 exposure times without S9 mix: 3 and 24 hours, and one exposure time with S9 mix: 3 hours; this experiment with S9 mix was carried out twice. Acetone was used as solvent for the test item and as the negative reference item.In the preliminary experiment without and with metabolic activation pronounced cytotoxicity (decreased survival) was noted from a concentration of 25 μg/mL onwards. Hence, in the experiments without or with metabolic activation the concentration rangeof 1.56 to 25 μg/mL was used. In the main study, cytotoxicity (decreased survival) was noted at the top concentration of 25 μg/mL immediately after treatment (plating efficiency step 1) in the experiments without and with metabolic activation. Methylmethanesulfonate was employed as positive control in the absence of exogenous metabolic activation and 3-Methylcholanthrene in the presence of exogenous metabolic activation.The mean values of mutation frequencies of the solvent controls ranged from 21.43 to 21.98 per 106 clonable cells in the experiments without metabolic activation, and from 21.19 to 21.50 per 106 clonable cells in the experiments with metabolic activation and, hence, were well within the historical data-range.

The mutation frequencies of the cultures treated with the test substanceranged from 19.21 to 36.96 per 106 clonable cells (3 hours exposure) and 19.55 to 33.08 per 106 clonable cells (24 hours exposure) in the experiments without metabolic activation and 21.14 to 37.97 per 106 clonable cells (3 hours exposure, first assay) and 19.94 to 36.31 per 106 clonable cells (3 hours exposure, second assay) in the experiments with metabolic activation. These results were within the range of the solvent controls and, hence, no mutagenicity was observed according to the criteria for assay evaluation.In addition, no change was observed in the ratio of small to large mutant colonies, ranging from 0.50 to 1.75 for the test substancestreated cells and from 0.88 to 1.59 for the solvent controls.Under the present test conditions,the test substance, tested up to a cytotoxic concentration of 25 µg/mL in the absence and presence of metabolie activation in two independent experiments, was negative with respect to the mutant frequency in theLK5178Y TK +/- mammalian cell mutagenicity test. Under these conditions positive controls exerted potent mutagenic effects. In addition, no change was noted in the ratio of small to large mutant colonies. Therefore, the test substancealso did not exhibit clastogenic potential at the concentration-range investigated. According to the evaluation criteria for this assay, these findings indicate that the test substancetested up to a cytotoxic concentration of 25 µg/mL in the absence and presence of metabolie activation did neither induce mutations nor had any chromosomal aberration potential.

Dioctylether is used as a read-across substance for distearylether. The only difference is the longer alkyl chain. Dioctylether is regarded as a worst case in this respect because of the higher bioavailability due to the lower molecular weight. Furthermore, the possible metabolite stearyl alcohol does not represent a genotoxic substances. It is unlikely that the ether of stearyl alcohol which is might be build in the human body is a genotoxic substance.

Short description of key information:
Dioctadecyl ether was not mutagenic in S. typhimurium TA 1535, TA 1537, TA 98 and TA 100 and E. coli WP2pKM101 and WP2 uvrA pKM 101. The homolog dioctylether did not induce structural chromosome aberrations as determined by the chromosome aberration test in V79 cells (Chinese hamster cell line) in-vitro. The homolog dioctylether tested up to a cytotoxic concentration of 25 µg/mL in the absence and presence of metabolie activation did neither induce mutations nor had any chromosomal aberration potential.

Endpoint Conclusion: No adverse effect observed (negative)