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A lack of mutagenic activity for the alkyl sulfates category is predictable based on structural and mechanistic considerations. Mutagens are chemicals that either 1) contain highly reactive electrophilic centers capable of interacting with nucleophilic sites on DNA (direct acting agents) or 2) can be metabolized to highly reactive electrophiles. The chemical structures represented by this chemical class do not contain electrophilic functional groups or functional groups capable of being metabolized to electrophiles. Alkyl sulfates with fully saturated carbon chains are not metabolized to reactive electrophiles. The consistent lack of mutagenic activity with alkyl sulfates is consistent with these mechanistic predictions.

There is no study regarding genotoxicity available for C9-11 AS Na (CAS 84501-49-5). Therefore this endpoint is covered by read across to structurally related alkyl sulfates (AS) for weight-of-evidence approach, i.e. C12 AS Na (CAS 151-21-3), C8 AS Na (CAS 142-31-4), C10 AS Na (CAS 142-87-0) and C8 AS Na (CAS 126-92-1). The possibility of a read-across to other alkyl sulfates in accordance with Regulation (EC) No 1907/2006 Annex XI 1.5 “Grouping of substances and read-across approach” was assessed. In Annex XI 1.5 it is given that a read-across approach is possible for substances whose physicochemical, toxicological and ecotoxicological properties are likely to be similar or follow a regular pattern as a result of structural similarity. The AS reported within the AS category show structural similarity. The most important common structural feature of the category members is the presence of a predominantly linear aliphatic hydrocarbon chain with a polar sulfate group, neutralized with a counter ion. This structural feature confers the surfactant properties of the alkyl sulfates. The surfactant property of the members of the AS category in turn represent the predominant attribute in mediating effects on mammalian health. Therefore, the AS of the AS category have similar physicochemical, environmental and toxicological properties, validating the read across approach within the category. The approach of grouping different AS for the evaluation of their effects on human health and the environment was also made by the OECD in the SIDS initial assessment profile [1] and by a voluntary industry programme carrying out Human and Environmental Risk Assessments (HERA [2]), further supporting the read across approach between structurally related AS.

Mutagenicity in bacteria

Mutagenicity in bacteria was assessed in a study performed according to OECD Guideline 471. Tester strains TA 102 or E.coli were not used during the conduct of the study (Banduhn, 1988). In the study with C12 AS Na (CAS 151-21-3) Salmonella typhimurium strains TA 1535, TA 1537, TA 98, TA 1538 and TA 100 were treated using the plate incorporation method with and without the addition of a rat liver S9-mix. The dose range was 8, 40, 200, 1000, 5000 µg/plate for the first experiment (with and without S9 mix) as well as 5, 10, 20, 40, 80 µg/plate (-S9 mix) and 2.5, 10, 40, 160, 640 µg/plate (+S9 mix) for the second experiment. Results achieved with vehicle (water) and positive controls were valid. Cytotoxicity was observed in presence and absence of metabolic activation occasionally around 200 µg/plate while no genotoxicity was observed for C12 AS Na (CAS 151-21-3) at all.

In the study, performed according to OECD Guideline 471, Salmonella typhimurium strains TA 1535, TA 1537, TA 98, TA 1538 and TA 100 were treated with C8 AS Na (CAS 142-31-4, analytical purity 40%) in presence and absence of metabolic activation (Banduhn, 1989). The tester strains TA 102 or E.coli WP2 were not used during the conduct of the study. The concentrations tested were 8, 40, 200, 1000 and 5000 µg/plate in both experiments. Results achieved with negative control (untreated and medium), vehicle (water) and positive controls were valid. Cytotoxicity was observed at 5000 µg/plate. No genotoxicity was observed.

In the study, performed according to OECD Guideline 471, Salmonella typhimurium strains TA 1535, TA 1537, TA 98, TA 1538 and TA 100 were treated with C10 AS Na (CAS 142-87-0, analytical purity 29-30%) in presence and absence of metabolic activation (Banduhn, 1992). The tester strains TA 102 or E.coli WP2 were not used during the conduct of the study. The concentrations tested were 8, 40, 200, 1000 and 5000 µg/plate in both experiments. Results achieved with negative control (untreated cell suspension and medium), vehicle (water) and positive controls were valid. Cytotoxicity was observed at 5000 µg/plate. No genotoxicity was observed.

Genotoxicity in mammalian cells

The clastogenicity of C8 AS Na (CAS 126-92-1, analytical purity 39.6%) in a mammalian cell line was investigated similar to OECD guideline 473 using Chinese hamster Ovary cells with and without metabolic activation (Loveday, 1990). The test concentrations were 501, 1500 and 5010 µg/mL. Results achieved with the vehicle (water) and positive controls were valid. No cytotoxicity was observed in presence and absence of metabolic activation however the test was conducted up to the limit concentration of 5000 µg/mL. No enhanced chromosome aberration was observed under any conditions of the study.

Mutagnicicty in mammalian cells

The potential of C8 AS Na (CAS 126-92-1, no data on analytical purity) to induce genmutation in mammalian cells in vitro was assessed in a study conducted similar to OECD guideline 476 using the mouse lymphoma L5178Y cells with and without metabolic activation (McGregor, 1991). The study comprised of 4 trials with and without metabolic activation. The concentrations tested in the absence of metabolic activation were 156.25, 312.5, 625, 1250, 2500 µg/mL (Trial 1); 200, 1000, 1800, 2600, 3400, 4200 µg/mL (Trial 2); 1000, 1800, 2600, 3400, 4200 µg/mL (Trial 3) and 1000, 1800, 2600, 3400, 4200, 5000 µg/mL (Trial 4). The concentrations tested in the presence of metabolic activation were 200, 1000, 1800, 2600, 3400, 4200 µg/mL (Trial 1), 1000, 1800, 2600, 3400, 4200 µg/mL (Trial 2&3) and 2600, 3000, 3400, 3800, 4200 µg/mL (Trial 4). No treatment related increased mutation frequencies were observed in three of four trials without S9 mix. However, in trial 3, all concentrations showing no marked cytotoxicity were associated with significantly increased mutation frequencies in the absence of metabolic activation. There was no reasonable explanation for this striking result of trial 3. In trial 1 without metabolic activation a statistically significant increased mutation frequency occurred at a single concentration level. At higher concentrations no increased mutation frequencies were observed within this trial. Taken together no increased mutation frequency was evidenced when L5178Y cells were exposed to the test substance without metabolic activation. In the presence of metabolic activation no increased mutation frequencies were observed. In two trials the top dose of 4200 µg/L produced marked cytotoxicity. Therefore also no increased mutation frequency was evidenced when L5178Y cells were exposed to the test substance with metabolic activation.

The mutagenicity of C12 AS Na (CAS 151-21-3, no data on analytical purity) in a mammalian cell line was investigated similar to OECD guideline 476 using the mouse lymphoma L5178Y cells with and without metabolic activation (McGregor, 1988). The test concentrations were 3.125, 6.25, 10, 12.5, 20, 25, 30, 40, 50, 55, 60, 65, 70, 80 and 100 µg/mL without and 50, 55, 60, 65, 70, 75, 80, 85, 90 and 95 µg/mL with metabolic activation. Results achieved with the negative (untreated), vehicle (DMSO) and positive controls were valid. Cytotoxicity was observed in presence and absence of metabolic activation while no genotoxicity was observed under both circumstances for C12 AS Na (CAS 151-21-3).

Genotoxicity in vivo

The potential of C12 AS Na (CAS 151-21-3) to induce in vivo chromosomal aberration was assessed in a study comparable to the dominant lethal test with CD-1 mouse (Unilever, 1976). The test substance was administered via gavage at doses of 120, 380 and 1200 mg/kg bw to a total of 225 males. Each male was caged with 2 virgin females for 7 days. Thereafter males were caged with another two virgin females for 7 days. This was repeated another 6 times. The males were not further examined. Females were sacrificed 13 days after the assumed date of fertilization, i.e.15 or 16 days after caging females with male and the frequency of early death, frequency of pregnancy and number of implantations was assessed. No adverse effects on and the frequency of early death, frequency of pregnancy and number of implantations occurred. Thus the test substance did not show clastogenicity at doses of 120, 380 and 1200.

In conclusion, the read across substances did not show any genotoxic potential. This is supported by the conclusions of the HERA Draft report “AS are not genotoxic, mutagenic or carcinogenic…” and the conclusions of the SIDS initial assessment profile “Alkyl sulfates of different chain length and with different counter ions were not mutagenic in standard bacterial and mammalian cell systems [...]. There was also no indication for a genotoxic potential of alkyl sulfates in various in vivo studies on mice […].”

 

[1] SIDS initial assessment profile, (2007); http://www.aciscience.org/docs/Alkyl_Sulfates_Final_SIAP.pdf

[2] (HERA Draft report, 2002); http://www.heraproject.com/files/3-HH-04-%20HERA%20AS%20HH%20web%20wd.pdf


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

Short description of key information:
In vitro gene mutation:
Bacterial reverse mutation assay (Ames test / OECD guideline 471): negative
In vitro mammalian chromosome aberration test (CA / OECD guideline 473): negative
In vitro mammalian cell gene mutation assay (MLA / OECD guideline 476): negative

In vivo clastogenicity:
In vivo study comparable to the dominant lethal test (DLA / OECD guideline 478): negative

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

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