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Administrative data

Description of key information

Classification of skin irritation  was based on read across substance 'Butanedioic acid, 2(or 3)-sulfo-, 4-[2-[(1-oxo(C12-C18(even numbered) and C18unsaturated)alkyl))amino]ethyl]esters, disodium salts'.  The read across test substance containing 39.8b% active ingredient was predicted to be irritant to human skin based on the three-dimensional EST 1000 human skin model (20 minutes exposure, follow by 42 hours incubation); the mean cell viability was 1.3%  after a 20-minute exposure followed by 42 hours incubation, which was under 50% threshold level. However it was negative for corrosion in the same test model (3 minutes and 1 hour exposure); the mean cell viability was 101.0%  and 78.0% after a 3-minute and 1-hour exposure, respectively, which were above threshold levels of 50 and 15%. Formulations of the registered substance however, containing  10%  or less active ingredient  were previously tested to be non-irritant based on Draize method, therefore CLP category 2 classification is proposed wiht trheshold for non classification at 10% or lower concentrations.  
Classification of eye irritation was based on read across substance 'Butanedioic acid, sulfo-, 1-[2-[(1-oxododecyl)amino]ethyl] ester, disodium salt'. The read across test substance containing 39.9 % active ingredient was predicted to be irritant to human eye based on the in vitro HET-CAM model; the test item treated eggs revealed an irritation index (IS) of 19, compared to19 for 0.1% NaOH. However it was not irritant in the in vivo eye irritation test. A4% solution of the restistered substance however was previously tested to be mildly irritant based on the Draize method in rabbit eyes, however not classified.

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not irritating)

Eye irritation

Endpoint conclusion
Endpoint conclusion:
adverse effect observed (irritating)

Respiratory irritation

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

Skin irritation

A. Weight-of-evidence was available for classification of skin irritation at concentrations of 39.8% active ingredient, based on read across with data of 'Butanedioic acid, 2(or 3)-sulfo-, 4-[2-[(1-oxododecyl)amino]ethyl]ester, disodium salt'. Justification for read across within the category of N-containing sulphosuccinates (N2 subcategory) is documented in a separate document attached in Section 13.

- In a first study, the corrosive properties were studied in an experiment with a three-dimensional EST-1000 human skin model (Flügge, 2013a). The test item (containing 39.8% active ingredient) was applied for exposure times of 3 minutes or 1 hour. The mean viability of cells exposed to the test item was 101.0% after a 3-minute exposure period and 78.0% after a 1-hour exposure. These values were well above the cut-off percentage cell viability values distinguishing corrosive from non-corrosive test items of <50% or <15% for a 3-minute or 1-hour treatment. Therefore, the test item was non-corrosive in this human skin model and is predicted to be non-corrosive to human skin.
- In a second study, the irritant properties to skin cells were also studied in an experiment with a three-dimensional EST-1000 human skin model (Flügge, 2013b). The test item (containing 39.8% active ingredient) was applied for an exposure time of 20 minutes, followed by refreshment of the medium and further 42 hours incubation. The mean viability of cells exposed to the test item was 1.3% of the negative controls and, hence, below the 50% cut-off value. The test item was considered to be cytotoxic and is predicted to be irritant to skin in accordance with UN GHS category 2. The viability of cells treated with the positive reference item, 5% SDS, was 1.3% of the negative controls and below the 50% cut-off value. Hence, 5% SDS is predicted to cause pronounced skin irritation.
- According to ECHA progress report 2010 (p. 32), it is accepted that in vitro methods for skin irritation represent a full replacement of the in vivo method in a tiered testing strategy and in conjunction with in vitro skin corrosivity tests, if necessary. A positive result in the human skin model for irritation does not need to be confirmed by additional testing and shall lead to classification.

B. Three supporting studies were available for the registered substance with formulations of 10% and lower.

- In a first acute dermal irritation/corrosion test on 6 albino rabbits (Oetjen and Lindena, 1990a) the potential toxicity of a test item containing 10% active ingredient was assessed. The skin was exposed to 0.5 mL for 4 h. Animals were examined for signs of erythema and oedema at 30-60 min, 24, 48 and 72 h after the end of the exposure period, showing absence of any signs up to 72 hours.
- In a second dermal irritation study in humans (Kligman, 1977) a 10-day occlusive patch test method was used as follows: 1, 5 and 10% concentrations were applied daily to the forearms of 10 young-adult female college students. 1% produced no visible reaction in any of the subjects. By the sixth day, some of the volunteers treated with 5% began to exhibit mild erythema which gradually worsened thereafter. The results with 10% were indistinguishable from the 5% concentration. 5 and 10% are mildly irritating when applied under continuous occlusion.The latter mode of exposure is, of course, greatly exaggerated in relation to normal use.
- In a third skin irritation study according to the modified methylene blue method in humans to study the desiccation on skin (Biefeldt and Schrader, 1991) 10mL of a 2% concentration was filled in a glass container and brought in contact with the skin of the forearms. After 15 seconds the product was discarded and the forearms were washed with 500 mL lukewarm water and blotted with paper towels followed by a 60 minutes rest period. Methylene blue solution was applied on the treated areas and further measured in the Zeiss spectrophotometer at 660nm against air. The test item was shown to be a mild detergent and falls in the category of low roughening.

 

Eye irritation

A. Weight-of-evidence was available for classification of eye irritation at concentrations (39.8% active ingredient), based on read across data of 'Butanedioic acid, 2(or 3)-sulfo-, 4-[2-[(1-oxododecyl)amino]ethyl]ester, disodium salt'. Justification for read across within the category of N-containing sulphosuccinates (N2 subcategory) is documented in a separate document attached in Section 13.

- In a first in vitro study theeye irritancy potential of test item containing 39.8% active ingredientwas testedby means of the chorioallantoic membrane of hens' eggs (HET-CAM) method (Haferkorn, 2012). Three eggseachwere treated with 300 µL/egg.After administration of the test item, blood vessels including the capillary system and the albumen were examined and scored for irritant effects (haemorrhage, coagulation and lysis) during 5 minutes. The test item treatedeggs revealed a pronounced effect with an irritation index (IS) of 19, compared to IS of 19 or 10 for 0.1% NaOH and 1% SDS positive controls and no effects in the negative control0.9% NaCl solution. The test item was predicted to be irritating.

- In a second in vitro study severe eye irritancy potential and corrosivity potential of the test item containing 39.8% active ingredient was tested by means of the BCOP test method (Leuschner, 2013).Three corneas were used for each treatment group (test item, negative and positive controls). The test item was used as a 3.98-fold dilution in 0.9% NaCl-solution in order to obtain a 10% w/v dilution of active ingredient, which complies with the guideline requirements for surfactants. 0.9% NaCl solution was used as the negative control and 1% NaOH solution as the positive control item. An IVIS score of 21.90 was calculated, hence the test item was not classified as a severe irritant and not corrosive, based on the results of this test. The corneas treated with the positive control item 1% NaOH solution revealed an IVIS score of 87.43 was well above the cut-off value of 55.1 and, hence, the acceptance criteria for the test were fulfilled. The test item, containing 39.8% active ingredient was consequently not classified as a severe irritant and is not corrosive.

- According to Column 2, the criteria for classification are met as irritating to eyes, based on weight of evidence, and further in vivo testing was therefore not needed.

B. Further in vivo studies were available for the read-across and registered substance with lower % formulations:

- In an in vivo study, Read-across substance 'Butanedioic acid, 2(or 3)-sulfo-, 4-[2-[(1-oxododecyl)amino]ethyl]ester, disodium salt' was tested according to the Draize mehod in rabbits (Baker Research Laboratories limited, 1962b). The test solutions were diluted with distilled water so that the content of active matter was reduced to 20% in each case. 0.1mL of the test solution (20% act. ingr.) was instilled into the conjunctival sac of one eye of each rabbit, the other eye serving as a control (3 rabbits were used). Readings were made visually and with the aid of an ophthalmoscope at 1, 2, 4, 6, 24, 48, 72 hours and 4 and 7 days after instillation and evaluated according to the Draize scoring method. Mild irritation was observed which was reversible within 3 days, which was below threshold of classification.

- Finally an in vivo study was also available with registered substance according to OECD Guideline 405 was available where 0.1 mL of test item containing 39% act.ingr. was instilled as a 10 % (v/v) aqueous solution into the conjunctival sac of the left eye of six White New Zealand rabbits (Oetjen and Lindena, 1990b). The eyes were not rinsed after substance application. Animals then were observed for 72 hours. At 1 h p.a. all animals showed slight redness and chemosis of the conjunctivae. At 24 hours p.a. slight conjunctival redness was still persistent in 5/6 animals and reversible in 1/6 animals. Chemosis persisted 24 hours p.a. only in 1/6 animals and was reversible in the other 5 animals. From 48 - 72 h p.a. no test article-dependent findings were observed. Active ingredient according to producers information: minimum 39 %.; taking this value into account, active ingredient of the test solution was 3.9 % in minimum.

- Based on these two in vivo studies and the structural similarity between registered and read-across substance, a concentration limit of 20% for non-classification can be set for the registered substance.

Conclusion:

- A subgroup CLP category 2 classification was decided for skin irritation, with concentration limit of 10% for non-classification of registered substance.
- A subgroup CLP category 2 classification was decided for eye irritation, with concentration limit of 20% for non-classification of registered substance.
- More information on the subgroup classification is provided in the read-across justification, separately attached in Section 13.


Justification for selection of skin irritation / corrosion endpoint:
Although the in vitro study for irritation was selected, the corrosion study was equally valuable in a weight-of-evidence approach.

Justification for selection of eye irritation endpoint:
Although the in vitro study for irritation was selected, the other studies were equally valuable in a weight-of-evidence approach.

Effects on skin irritation/corrosion: irritating

Effects on eye irritation: slightly irritating

Justification for classification or non-classification

The registered substance is classified for skin irritation according to the Directive 67/548/EEC, Annex VI with symbol Xi and the indication of “irritant”; the following risk phrase shall be assigned: R38 - Irritating to skin.  According to CLP regulation (No. 1272/2008 of 16 December 2008), the substance is classified as Category 2, with signal word 'warning' and hazard statement: H315 - Causes skin irritation. However, a concentration limit of 10% for non-classification can be applied.

For the eye, the test substance is classified as irritating to eyes and the risk phrase R36- Irritating to eyes shall be assigned. According to CLP regulation, the substance is classified as Category 2, with signal word 'warning' and hazard statement: H319 -Causes serious eye irritation. However, a concentration limit of 20% for non-classification can be applied.