Sodium alkyl sulphate

Endpoint summary

Description of key information

skin irritation (OECD 404): irritating
eye irritation (OECD 405): highly irritating/corrosive
SCLs according to GHS:
>10% -<20% Eye Irrit. Cat.2, R36
<= 10% No Classification

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Eye irritation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

There are no data regarding skin and eye irritation of C12-13AS Na (CAS 1231880-35-5) available. Therefore, a read across to structurally related AS, i.e. C12AS Na (CAS 151-21-3) and C12-14AS Na (CAS 85586-07-8) for skin as well as C12-13 AS Na (CAS 91783-23-2), C10-16AS Na (CAS 68585-47-7) and C12-13AS K (CAS 91783-22-1) for eye irritation was performed. 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.

skin irritation

The key study conducted with C12AS Na (CAS 151-21-3, analytical purity 100%) was performed similar to OECD Guideline 404 under occlusive conditions (Esposito, 1976). Each of six New Zealand White rabbits was exposed for 24 h to 0.5 mL of the unchanged test item and was observed for a period of 72 h for erythema and edema. The 48 h reading time point was missing. The mean erythema and edema score after 24 and 72 h were 2.2 and 1.7. Both were not reversible within 72 h. When using the higher value of the 24 and 72 h reading time point as value for the 48 h value (per animal) the mean erythema and edema score of all animals were 2.4 and 2.2, respectively. No details on the reversibility of the effects are available. Using the interpretation advice given within the study report, which is based on the primary irritation index of the substance, the test substance showed irritating properties.

The study conducted with C12-14AS Na (CAS 85586-07-8, analytical purity 30%) was performed similar to OECD Guideline 404 under occlusive conditions (Hixson, 1972). Each of three white rabbits was exposed for 24 h to 0.5 mL of the unchanged test item and was observed for a period of 72 h for erythema and edema. Only data of the unabraded test site were reported. The 48 h reading time point was missing. Therefore the 48 h score was extrapolated using the higher value of the 24 and 72 h reading time point as value for the 48 h value (per animal). The mean erythema scores after 24, 48 and 72 h were 3, 0.67 and 3 for animals 1, 2 and 3, respectively. No edema was observed in any animal at any reading time point. Erythema was not reversible within 72 h. Based on these data the test substance has to be classified as skin irritating.

Thus the test substance was classified as skin irritating Category 2 according to Regulation 1272/2008/EC and R38 according to Directive 67/548/EEC.

eye irritation 

There are several data regarding eye irritation of alkyl sulfates available. However, a read across from structurally related AS, i.e. C12-13AS Na (CAS 91782-23-2) for eye irritation was performed to provide a robust data base.

In a study, performed similar to OECD guideline 405, 0.1 mL of C12-13AS Na (CAS 91782-23-2, analytical purity 27%) was applied to one eye of each of six New Zealand White rabbits (Salvi, 1984). Eye reactions were scored 24, 48 and 72 h and 7 days after application. The mean (24, 48 and 72 h reading) cornea, iris, conjunctivae and chemosis scores were 0.3, 0.3, 3 and 3.5. The findings did not fully reverse within 7 days. Thus the test item produced irreversible effects on the eye at a concentration of 27%.

As corrosion and irritation depends on the concentration of the substance in a solvent, further studies with lower concentrations of the test substance were also considered to assess whether specific concentration limits can be set. For this purpose, one study with C12-13AS K (CAS 91783-22-1) and two studies with C10-16AS Na (CAS 68585-47-7) with a concentration range of 10 to 22% were evaluated.

In the study with C12-13AS K (CAS 91783-22-1, analytical purity 44%) 0.1 mL of the diluted test item (1:1 mixture with water) was applied to one eye of each of three New Zealand White rabbits according to OECD guideline 405 (Braun, 1978) without rinsing. In a second experiment with additional 3 rabbits the procedure was repeated but the treated eye was rinsed with 20 mL of lukewarm tap water 4 seconds after application of the test item. The eye reactions were recorded 1, 24, 48, 72 h and 4, 7, 14, 21 and 28 days in both experiments. The mean (24, 48 and 72 h reading) cornea, iris, conjunctivae and chemosis scores of experiment 1 were 2, 0.8, 2.1 and 1.7. The findings reversed in 2/3 animals within 14 days while 1/3 animals showed signs of irritation after 21 days. However, the signs of irritation show a clear tendency to decrease with time. No reading on day 28 was possible. Findings in the experiment with rinsing of the eye were less pronounced but irritating properties were also observed. As the ocular findings clearly reversed within 21 days the result of the study indicate the concentration of 22% to be the turning point between classification as severe damage to the eye and eye damaging.

The first study with 0.1 mL undiluted C10-16AS Na (CAS 68585-47-7, analytical purity 10%) was performed similar to OECD guideline 405 (Kukulinski, 1980a) on three New Zealand White rabbits with an observation period of 7 days. The mean (24, 48 and 72 h reading) cornea, iris, conjunctivae and chemosis scores over all animals were 1.4, 0.7, 2 and 1.6. Corneal opacity was still observed in 1/3 animals (scored 1) and conjunctival redness was still present in 2/3 animals (both scored 1) upon reading at day 7. Depending on the classification requirements the test substance is not or only moderate irritating to the eye at a concentration of 10%.

The second study with C10-16AS Na (CAS 68585-47-7, analytical purity 10%) was performed similar to OECD guideline 405 (Kukulinski, 1980b). 0.1 mL of the undiluted test item was instilled into one eye of each of three New Zealand White rabbits. Eye reactions were scored at least 24, 48 and 72 h and 14 days after application of the test item. The mean (24, 48 and 72 h reading) cornea, iris, conjunctivae and chemosis scores were 0.9, 0.7, 1.9 and 1.6. All findings were fully reversible within the observation period. Thus, the test substance showed no eye irritating properties at a concentration of 10%.

Based on the above mentioned results with different concentrations of structurally related alkyl sulfates a cut of value for classification as severe irritating to eyes is set at a concentration of 20% and for classification as irritating at a concentration of 10%.

respiratory irritation  

No data on respiratory irritation are available. AS is mainly used in liquid media and due to its very low vapour pressure [2] inhalation is not viewed as a significant route of exposure. Inhalation of AS may occur by inhalation of aerosols generated by spray cleaners or by inhalation of detergent dusts (e.g. washing powder). In both cases the substance will be used in low concentrations.

[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 skin irritation / corrosion endpoint:
Reliable OECD guideline study

Justification for selection of eye irritation endpoint:
Reliable OECD guideline study

Effects on skin irritation/corrosion: irritating

Effects on eye irritation: corrosive

Justification for classification or non-classification

According to the classification criteria of Directive 67/548/EEC and Regulation (EC) No 1272/2008 the test substance needs to be classified with Xi, R38/R41 and Skin Irritation Category 2, H315 and Eye Dam.1, H318, respectively.

It could be shown with experimental data on eye irritation that at 10 to 20% active substance only the classification Eye Irritating Category 2 according to Regulation (EC) No 1272/2008 and according to Directive 67/548/EEC only the classification R36 remains. Below 10% active substance no classification at all is necessary. Hence, the Generic Concentration Limits (GCLs) can be substituted by the mentioned specific ones (SCLs).