2,2'-[ethane-1,2-diylbis(oxy)]bisethyl diacetate

Endpoint summary

Additional information

Genetic toxicity

Gene mutation in bacteria

One study investigating the induction of gene mutation in bacteria by 2,2'-[ethane-1,2-diylbis(oxy)]bisethyl diacetate is available (NTP, 1989). The study was conducted similar to OECD guideline 471. The tester strains, Salmonella typhimurium TA 98 and TA 100 were used.

The experiments were performed according to the preincubation procedure at concentrations from 100-10000 µg/plate with and without a metabolic activation system (S9-mix from rats and hamsters). The included positive and negative controls in the experiments showed the expected results and were therefore considered as valid.

With metabolic activation, no increase in the number of revertant colonies was observed in the bacterial strains. However, without metabolic activation an increase in the number of revertant colonies was observed in both strains in two experiments. However, this increase was observed in TA 100 at concentrations ≥ 1000 µg/plate and in TA 98 ≥ 3333 µg/plate. The increase of revertant colonies in high concentrations of 2,2'-[ethane-1,2-diylbis(oxy)]bisethyl diacetate has to be discussed, as possible pH-effects of the test substance have not been evaluated in the study. Structurally related esters with acetic acid have shown a reduction of the pH-value of the incubation medium (Glycerol diacetin (technical)). In addition, Cifone et al. (1987) showed that conditions of non-physiological pH may affect the results of in-vitro genetic tests by mechanisms unrelated to the test substance. Furthermore, the predicted in-vivo breakdown product Triethyleneglycol (CAS 112-27-6, see Toxicokinetics) has shown no genetic toxicity in bacteria, as well (Final report on the safety assessment of Triethylene Glycol and PEG-4, 2006).

In vitro cytogenicity in mammalian cells

A study investigating the cytogenicity in mammalian cells in-vitro with 2,2'-[ethane-1,2-diylbis(oxy)]bisethyl diacetate (CAS 111-21-7) was performed similar to OECD guideline 473 (NTP, 1991). The induction of structural chromosome aberrations was evaluated in vitro in Chinese hamster ovary (CHO) cells, incubated for 2 h with and for 8 - 12 h without a metabolic activation system (S9-mix from rats treated with Aroclor 1245). Concentrations of 1081-5000 µg/mL of the test substance in the vehicle water were applied. The negative as well as the positive controls showed the expected results and were thus considered as valid. No statistically or biologically significant increase in the incidence of chromosome aberrations was observed. Therefore, under the conditions of the study, the test substance did not show clastogenic activity in the chromosomal aberration test with and without metabolic activation performed in CHO cells in vitro.

In addition, an in-vitro sister chromatid exchange (SCE) assay in mammalian cells with 2,2'-[ethane-1,2-diylbis(oxy)]bisethyl diacetate (CAS 111-21-7) is available (NTP, 1991). The study was performed similar to OECD guideline 479 in-vitro in Chinese hamster ovary (CHO) cells at concentrations from 167 - 5000 µg/mL and 1500 - 2500 g/mL without metabolic activation (experiment I and II) and 500 - 5000 µg/mL with metabolic activation (S9-mix from rats treated with Aroclor 1245, experiment III). The negative as well as the positive controls showed the expected results and were thus considered as valid.

In the three experiments of the sister chromatid exchange test (with and without metabolic activation), a dose-dependent statistically significant increases in SCE compared to the solvent control was observed. However, as discussed above no data about the pH value of the medium and no data about cytotoxicity was included in the test. Furthermore, the predicted in-vivo breakdown product Triethyleneglycol (CAS 112-27-6, see Toxicokinetics) has shown a negative result in the sister chromatid exchange assay, as well (Final report on the safety assessment of Triethylene Glycol and PEG-4, 2006).

Genetic toxicity in vivo

An in-vivo micronucleus assay with 2,2'-[ethane-1,2-diylbis(oxy)]bisethyl diacetate (CAS 111-21-7) was carried out according to OECD guideline 474 under GLP conditions (Flanders, 2012). Based on the results of a preliminary dose range finding study, the test substance was diluted in phosphate buffered saline and administered at 400, 800 and 1600 mg/kg bw as single intraperitoneal dose to groups of 7 male CD-1 mice, observed for 24 h and 48 h (only 1600 mg/kg bw) post-dose. A concurrent negative control with the vehicle alone and a positive control group given cyclophosphamide was included in the study. No mortality was observed in the main study. At 1600 mg/kg bw, in both the 24 and 48 h dose groups, hunched posture and ptosis were observed. The test substance did not induce a statistically significant increase in the number of micronucleated polychromatic erythrocytes of the treated animals. The negative and positive controls showed the expected results. Therefore, under the conditions of the study 2,2'-[ethane-1,2-diylbis(oxy)]bisethyl diacetate (CAS 111-21-7) did not induce chromosomal mutations in the bone marrow of mice.

Conclusion for genetic toxicity

In summary, the study with 2,2'-[ethane-1,2-diylbis(oxy)]bisethyl diacetate (CAS 111-21-7) investigating genetic mutations in bacteria in-vitro showed ambiguous results with metabolic activation in high test substance concentrations. However, the predicted in-vivo metabolite Triethylene glycol did not show genetic mutations in bacteria in-vitro (Final report on the safety assessment of Triethylene Glycol and PEG-4, 2006). Furthermore, cytogenicity in mammalian cells in-vitro provided negative results, however an in-vitro sister chromatid exchange assay showed positive results. The predicted in-vivo metabolite Triethylene glycol showed negative results in an SCE assay. In an in-vivo mammalian erythrocyte micronucleus test with 2,2'-[ethane-1,2-diylbis(oxy)]bisethyl diacetate (CAS 111-21-7), negative results were obtained.

Therefore, 2,2'-[ethane-1,2-diylbis(oxy)]bisethyl diacetate (CAS 111-21-7) is not considered to be genotoxic.

Justification for selection of genetic toxicity endpoint
Hazard assessment is conducted on the basis of substance-specific data and 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 substance and overall quality assessment (refer to the endpoint discussion for further details).

Short description of key information:
In vitro gene mutation in bacteria: negative
In vitro cytogenicity in mammalian cells: negative
In vivo genetic toxicity: negative

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

The available data on genetic toxicity of 2,2'-[ethane-1,2-diylbis(oxy)]bisethyl diacetate (CAS 111-21-7) do not meet the criteria for classification according to Regulation (EC) 1272/2008 or Directive 67/548/EEC, and the data are therefore conclusive but not sufficient for classification.