Sodium nonyl sulphate

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 skin sensitisation with C9AS Na (CAS 1072-15-7) available. Therefore this endpoint is covered by read across to structurally related alkyl sulfates (AS), i.e. C8AS Na (CAS 142-31-4) and C12AS 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 physico-chemical, 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.

 

One study assessed the skin sensitizing potential of C8AS 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 C12AS Na (CAS 151-21-3) was assessed in a local lymph node assay similar to OECD guideline 429 (Ikarashi, 1993) on 3 mice per dose and experiment. 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.

 

Results of the above mentioned study show that C8AS Na and C12AS Na is not skin sensitising. In addition, sodium lauryl sulphate (C12AS Na) was used within the above mentioned study as known irritant to produce irritant effects. Likewise sodium lauryl sulphate is also recommended as an agent to induce local irritation in an OECD method to assess skin sensitising properties of chemicals (OECD guideline 406, Guinea Pig Maximisation Test). Thus, skin sensitisation by members of the alkyl sulfates is generally unlikely.

References:

[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:
Both studies are performed according to OECD guideline 429 with a negative outcome. Therefore no study was chosen.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

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 skin sensitization. No data is available for respiratory sensitization.