Sodium etasulfate

Endpoint summary

Description of key information

skin irritation (OECD 404): irritating
eye irritation (worst case assumption): 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

One study regarding skin irritation and one study regarding eye irritation are available with C8iso AS Na (CAS 126-92-1). However both studies were performed with concentrations of approx. 37.5%. Therefore a read across to structurally related AS, i.e. C8 AS Na (CAS 142-31-4) for skin irritation and C10-16 AS Na (CAS 68585-47-7) and C12-13 AS 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

There is one relevant study C8iso AS Na (CAS 126-92-1) available addressing skin irritation.

The supporting study was performed with C8iso AS Na (CAS 126-92-1, analytical purity: 37.5%) similar to OECD Guideline 404 under occlusive conditions (Thomann, 1978). Each of six rabbits of the Russian strain was exposed for 24 h to 0.5 mL of the unchanged test item and was observed for a period of 7d for erythema and edema. The mean erythema and edema score after 24, 48 and 72 h were 0.61 and 0.22. The erythema was fully reversible within 72 h and the edema was fully reversible within 48 h. Thus the test substance does not meet the criteria for classification according to Regulation (EC) 1272/2008 or Directive 67/548/EEC at a concentration of 37.5% a.i under the stringent conditions used within this study.

The skin irritating property of neat C8iso AS Na (CAS 126-92-1) is assessed via read-across to the structural related alkyl sulfate C8 AS Na (CAS 142-31-4). The skin irritating property of neat C8iso AS Na (CAS 126-92-1) is assessed via read-across to the structural related alkyl sulfate C8 AS Na (CAS 142-31-4). In an OECD guideline 404 study, C8AS Na (CAS 142-31-4) was applied to 3 New Zealand rabbits under semi-occlusive conditions for 4 h. Skin reactions were scored 1, 24, 48 and 72 h. The observation period was 14 d. Clinical observations comprised of scaling to severe scaling, incrustations, eczema like lessions, bloody, yellowish incrustations, yellowish discoloration of application site and plaque like incrustations. The mean erythema score after 24, 48 and 72 h was 3 for each rabbit. The mean edema scores after 24, 48 and 72 h were 2, 3.3 and 3 for animals 1, 2 and 3, respectively. Erythema and edema were not fully reversible within 14 d. 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. As the neat substance has to be classified as skin irritating, the substance will also be classified as “may cause respiratory irritation” (STOT SE3, H335 and R37, respectively) in case the substance is available as neat powder.

Eye irritation

There are several studies investigating the eye irritating potential of alkyl sulfates (AS) which have shown that AS concentrations of 10% and higher are moderately to strongly irritating to rabbit eyes and that formulations containing more than 20% AS can cause serious eye damage. Unless data are available that show absence of the irritating potential as defined by the EC criteria the classification Xi, R41 according to Directive 67/548/EEC and Eye Dam. 1, H318 according to Regulation (EC) 1272/2008 will be applied for the neat substance.

One study regarding the eye irritating potential of C8iso AS Na (CAS 126-92-1, analytical purity: 37.5%) is available. 0.1 mL undiluted test substance was instilled to one eye of each of three rabbits of the Russian strain without rinsing. The observation period was 8 days. The mean (24, 48 and 72 h reading) cornea, iris, conjunctivae and chemosis scores over all animals were 1.33, 1.0, 1.2 and 0.89. Corneal opacity was still observed in 3/3 animals (scored 1), conjunctival redness was still present in 2/3 animals (both scored 1) and chemosis (scored 1) was observed in 1/3 animals upon reading at day 8. The maximum scores were observed at the 6 h reading time point. All scores decreased until day 8. Although no data on the reversibility until day 21 are available the trend suggests the eye irritating effects to be reversible. Therefore, at a concentration of 37.5% the test substance is classified as Eye Irritating Category 2 and R36, respectively.

 

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

In the study with C12-13 AS 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 reversible eye damaging.

The first study with 0.1 mL undiluted C10-16 AS 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 C10-16 AS 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 off 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%.

The eye irritation study with C8iso AS Na (CAS 126-92-1) indicates the test substance at a concentration of 37.5% to be eye irritating only (Cat 2 and R36, respectively). Therefore the specific concentration limits at 10 and 20% represent a worst case scenario for C8iso AS Na (CAS 126-92-1).

 

[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:
No study selected as woe approach was followed.

Justification for selection of eye irritation endpoint:
Worst case assumption

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 is classified with Xi, R38/R41 and Skin Irrit. 2, H315 and Eye Dam.1, H318.

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).