Sulfuric acid, mono-C8-14-alkyl esters, ammonium salts, compds. with triethanolamine

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

There is no reliable study on skin and eye irritation of C8-14AS NH4&TEA (CAS 96690-74-3) available. Therefore a read across to structurally related AS, i.e. C8AS Na (CAS 142-31-4) and C12AS Na (CAS 151-21-3) for skin irritation and 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. During evaluation of the human health hazards of the alkyl sulfates within the AS category it turned out that alkyl sulfates with a C12 carbon chain length bear the most concern for potential adverse effects on human health. Alkyl sulfates of this chain length have to be classified as harmful if swallowed while alkyl sulfates having a chain length of C8 and higher than C14 does not have to be classified for acute toxicity after oral ingestion. The same trend is also seen for the irritating properties of alkyl sulfates. This was shown in two in vivo in vitro studies and as well on human volunteers (details are given in the category justification). Therefore the read-across to C12AS is expected to be valid.

The contribution of TEA to the endpoint irritation was already evaluated in the HERA report [2]. There it was given that TEA salts are less irritating than the sodium salts. Furthermore local effects of the fore stomach observed after repeated treatment via gavage were partially reversible for C12AS Na and fully reversible for C12-14AS TEA. Therefore the read-across to sodium alkyl sulfates is expected to be valid. There is further a substantial data base on triethanolamine (TEA) online available. TEA is not listed in Annex VI of directive 1272/2008. In addition the effects of TEA on human health were assessed by the OECD in the SIDS initial assessment Report [3]. Despite of some local signs of irritation TEA gives no rise to concern of adverse effects on human health. Therefore a contribution of TEA to the effects on human health is considered to be negligible when assessing human health effects of C8-14AS NH4&TEA (CAS 96690-74-3). Ammonium sulfate is used to produce AS NH4 within the current AS category. There is a substantial data base on ammonium sulfate online available. Ammonium sulfate is not listed in Annex VI of directive 1272/2008. In addition the effects of ammonium sulfate on human health were assessed by the OECD in the SIDS initial assessment Report [4]. Ammonium sulfate gives no rise to concern of adverse effects on human health. Therefore a contribution of ammonium sulfate to the effects on human health is considered to be negligible when assessing human health effects of C8-14AS NH4&TEA (CAS 96690-74-3).

Thus, read across to alkyl sulfates with other counter ions is considered to be valid and reliable. This approach was also followed by the OECD in the SIDS initial assessment profile [1] and by the voluntary industry programme carrying out Human and Environmental Risk Assessments (HERA [2]).

 

Skin irritation

The skin irritating property of C8-14AS NH4&TEA (CAS 96690-74-3) is assessed via read-across to the structurally related alkyl sulfates, i.e. C8AS Na (CAS 142-31-4) and C12AS Na (CAS 151-21-3). 

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.

The relevant study conducted with C12AS Na (CAS 151-21-3) 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 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. 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

Based on the available data C8-14AS TEA (CAS 85665-45-8) is assumed to be irritating to the skin. 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.

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 a read across to structurally related AS, i.e C12-13AS K (CAS 91783-22-1) and C10-16 AS Na (CAS 68585-47-7)with a concentration range of 10 to 22%was performed.

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. In experiment 1, the mean (24, 48 and 72 h reading) cornea, iris, conjunctivae and chemosis scores were 2, 0.8, 2.1 and 1.7, respectively. 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 borderline between classification as severe damage to the eye and reversible 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, 1980) 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, respectively. 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, 1980).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, respectively. 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%.

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

[3] SIDS initial assessment report, (1995);

http://webnet.oecd.org/HPV/UI/SIDS_Details.aspx?Key=5ca67317-5fcc-41ea-a429-53d1267be383&idx=0

[4] Referenz available at:

http://webnet.oecd.org/HPV/UI/SIDS_Details.aspx?Key=2c80d506-86bf-4719-be9b-d922022506ec&idx=0

Justification for selection of skin irritation / corrosion endpoint:
No study selected as both studies are reliable and result in the same classification.

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 needs to be 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).