Sulfuric acid, mono-C9-11-alkyl esters, sodium salts

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

There is no study regarding sensitisation 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. C8 AS Na (CAS 142-31-4) and C12 AS Na (CAS 151-21-3). 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.

Sensitisation

There is one study regarding skin sensitisation with C8 AS Na (CAS 142-31-4) and a second study with C12 AS Na (CAS 151-21-3) available.

One study assessed the skin sensitizing potential of C8 AS Na (CAS 142-31-4, analytical purity 32%) in a local lymph node assay similar to OECD Guideline 429 (P&G, 1992). In this study 12.5 µL of a 10, 50 and 100% aqueous solution of the test substance were topically applied on 4 consecutive days to 5 female CBA mice per dose group. 21 h after the last treatment all animals received injections with radiolabelled thymidine. Animals were sacrificed 5 h thereafter and auricular lymph nodes were removed. Single cell suspensions were prepared, washed and precipitated. The total radio counts in these precipitates were subsequently quantified by liquid scintillation spectrometry. The stimulation index in the carrier control was 1. The stimulation indices for the naïve control and animals treated with 10, 50 and 100% of the test substance were 2.4, 1.25, 2.7 and 3.1, respectively. The treatment had no significant effect on thymidine incorporation and thus the test substance showed not sensitising potential.

The skin sensitizing potential of C12 AS Na (CAS 151-21-3) was assessed in a local lymph node assay similar to OECD guideline 429 on 3 mice per dose and experiment (Ikarashi, 1993). BALB/c mice were treated daily via topical application (25 µL) of 5, 10 and 25% aqueous solution of the test item on 3 consecutive days. In another experiment intradermal injections (50 µL) were performed with concentrations of 0.05, 0.5 or 5% in saline. Five days after intradermal injection, mice were challenged daily by dermal application of 25 µL of a 5% solution in vehicle (DMSO 50%) on the ears for 3 consecutive days. The day after the final exposure, changes in lymph node weight, total cell number in the draining lymph nodes and LNC proliferation for 24 h culture were assessed. The stimulation indices in the first experiment were 0.7, 1.6 and 1.1 at 5, 10 and 25%. After intradermal application of 0.05, 0.5 or 5% test item and subsequent dermal challenge with 5% test item the stimulation indices were 1.6, 1.9 and 1.5.

Based on the above mentioned results, the data of the read-across substance C8 AS Na (CAS 142-31-4) and C12 AS Na (CAS 151-21-3) indicates no skin sensitisation potential. Therefore, C9-11 AS Na (CAS 84501-49-5) is not expected to be a skin sensitiser. Moreover, an alkyl sulfate, i.e. sodium lauryl sulphate (C12 AS Na) is recommended as an agent to induce local irritation in a method to assess skin sensitising properties of chemicals (OECD guideline 406, Guinea Pig Maximisation Test). Hence, there is a lot of experience with sodium lauryl sulfate in sensitising studies and no evidence occurred that it shows sensitising properties. Thus, skin sensitisation by members of the alkyl sulfates is generally unlikely.

 

[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

Migrated from Short description of key information:
Skin sensitisation (LLNA - OECD 429): not sensitising

Justification for selection of skin sensitisation endpoint:
No study chosen as weight of evidence approach was followed.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

The available data on skin sensitisation do not meet the criteria for classification according to Regulation (EC) 1272/2008 and are therefore conclusive but not sufficient for classification.

No data available for respiratory sensitisation.