Alcohols, C9-11, ethoxylated

Endpoint summary

Additional information

To cover the endpoint genotoxicity of substance C9-11AE (CAS 68439-46-3), studies from similar substances were taken for read-across. Read-across is justified because the length of the alkyl chain and the grade of ethoxylation does not exert any meaningful influence on genotoxicity. Moreover, the structure of alcohol ethoxylates (AE) is not of concern for potential genotoxicity and in all available in-vitro and in-vivo genotoxicity assays, there was no indication of genetic toxicity of broad range of structurally different AE (HERA, 2009).

Mutagenicity in bacteria was assessed in studies performed with C12-14AE (CAS 68439-50-9), C6-10AE (CAS 112-59-4) and C12-15AE (CAS 68131-39-5) according or equivalent to OECD Guideline 471.

In the first study C12-14AE (CAS 68439-50-9) Salmonella typhimurium strains TA 1535, TA 1537, TA 98, TA 100 and TA 1538 were treated using theplate incorporation method in triplicates, both with and without the addition of a rat liver S9-mix (Thompson, 1996). The dose range was determined in a preliminary toxicity assay and ranged between 1.5 and 5000 µg/plate in the first experiment. The vehicle (DMSO) control plates produced counts of revertant colonies within the normal range. All positive controls used in the test induced marked increases in the frequency of revertant colonies, both with and without the metabolising system. The test material caused a visible reduction in the growth of the bacterial lawn to all of the strains of salmonella tested. The sensitivity of the bacterial strains to the toxicity of the test material varied between strains and between exposures with or without S9-mix. The first incidence of toxicity was recorded at 150 µg/plate. The test material was, therefore, tested up to its toxic limit. Thus, under the conditions of this test the test substance can be regarded as not mutagenic in bacteria.

The second study with C6-10AE (CAS 112-59-4) and the same set of Salmonella strains assessed the mutagenic potential at 0.1, 0.3, 1.0, 3.0, 10.0 mg/plate in the presence and at 0.03, 0.1, 0.3, 1.0, 3.0 mg/plate in the absence of metabolic activation by rat liver S9-mix (Ballantyne, 2001). Complying with the results of the first study, the vehicle (DMSO) control and test plates produced counts of revertant colonies within the normal range whereas all positive controls induced marked increases in the frequency of revertant colonies. Like mentioned in the first study, cytotoxicity was present in the higher concentrations marking the test substance clearly as non-mutagenic in bacteria.

The last study with C12-15AE (CAS 68131-39-5) confirmed the results of the former ones, this time comprising besides the Salmonella strains E. coli WP2 and WP2 uvrA strains (Dean 1980). The tested concentrations with and without metabolic activation were 0.2, 2, 20, 200, 2000 µg/plate, showing no mutagenic effects at all.

 

The clastogenic potential was assessed in a chromosomal aberration test in mammalian cells with C12AE (CAS 9002-92-0) equivalent to OECD Guideline 473 (Loveday, 1990). Chinese hamster ovary cells (CHO) were exposed to 5, 15 and 50 µg/mL for 8 hours with and 2 hours without S9-mix. Positive and vehicle (water) control cultures were included in each assay. No increases in the number of chromosome aberrations in the presence or absence of metabolic activation were seen at any concentration tested. Appropriate reference mutagens used as positive controls showed a significant increase in chromosome aberrations, thus indicating the sensitivity of the assay, and the efficacy of the S9-mix. Hence, the test substance can not be regarded as clastogenic.

 

The mutagenic potential in mammalian cells was assessed with C6-10AE (CAS 112-59-4) by a HPRT-assay equivalent to OECD Guideline 476 (Ballantyne 2001b). Following pre-tests with the concentration ranging from 0.01-10.0 mg/mL, Chinese hamster ovary cells were exposed to test substance at concentrations of 0.25, 0.75, 1.0, 1.5 and 2.0 mg/mL in the absence of metabolic activation for 5 hours and at concentrations of 0.1, 0.25, 0.75, 1.0, 1.5, 2.0 and 2.5 mg/mL in the presence of metabolic activation by rat liver S9-mix for 2 hours, respectively. The cytotoxicity data obtained 24 h after exposure of cells to the test substance showed a dose-related effect both with and without metabolic activation, as shown by the total cells per culture. In contrast, the plating efficiency was essentially similar for all concentrations, indicating that the primary cytotoxic effect was cell death or lysis but the survivors recovered their ability to grow and form colonies. No dose-related increases in mutant colony numbers were obtained in two independent experiments with the test substance in either the presence or absence of S9-mix. Appropriate reference mutagens used as positive controls produced highly significant increases in mutation frequency, thus indicating the sensitivity of the assay. Therefore, the test substance is regarded as not mutagenic in mammalian cells.

The mutagenic potential in mammalian cells was further assessed with C12-14AE (3 EO, CAS 68439-50-9) by an unscheduled DNA Synthesis test similar to OECD Guideline 482 (Sansebastian, 1990). Following pre-tests with the concentration ranging from 0.1-5000 µg/mL, primary rat hepatocytes were exposed to test substance at concentrations of 0.25, 0.5, 1.0 and 2.5 µg/mL and 10 µC/mL of H-thymidine for 18 – 20 h. After fixation and staining 150 hepatocytes per concentration, i.e. 50 cells/coverslip, were evaluated auto-radiographically for the appearance of black silver grains. No dose-related increase in the net nuclear grain (NNG) count was observed. An appropriate reference mutagen (2AAF) used as positive control produced significant increased NNG counts, thus indicating the sensitivity of the assay. Therefore, the test substance is regarded as not mutagenic in mammalian cells. 

In conclusion, C9-11AE (CAS 68439-46-3) is regarded as non-genotoxic.

Justification for selection of genetic toxicity endpoint
No study selected as all results were negative.

Short description of key information:
Ames (OECD 471): not mutagenic in bacteria
Chromosomal Aberration (OECD 473): not clastogenic in mammalian cells
HPRT (OECD 476): not mutagenic in mammalian cells
UDS (OECD 482): not mutagenic in mammalian hepatocytes

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

According to the classification criteria of Directive 67/548/EEC and Regulation (EC) No 1272/2008 the substance does not need to be classified for genotoxicity.