Registration Dossier

Administrative data

Description of key information

A key study for the assessment of skin sensitization to Butanedioic acid, sulfo-, 4-C16-18 (even numbered)-alkyl esters, disodium salts was done in the Mouse (Local Lymph Node Assay) at test item concentrations of 10, 25 or 50% w/w. No erythema was observed in any of the animals. All auricular lymph nodes of the animals of the experimental and control groups were considered normal in size. No macroscopic abnormalities of the surrounding area were noted for any of the animals. Mean DPM/animal values for the experimental groups treated with test item concentrations 10, 25 and 50% were 1019, 1496 and 1329 DPM (desintegrations per minute), respectively. The mean DPM/animal value for the vehicle control group was 943 DPM. The SI (stimulation index) values calculated for the test item concentrations 10, 25 and 50% were 1.1, 1.6 and 1.4, respectively. Since there was no indication that the test item elicited a SI ≥ 3 when tested up to 50%, Butanedioic acid, sulfo-, 4-C16-18 (even numbered)-alkyl esters, disodium salts was not considered to be a skin sensitizer (Latour, 2016).

A Direct Peptide Reactivity Assay (DPRA) with Butanedioic acid, sulfo-, 4-C16-18 (even numbered)-alkyl esters, disodium salts was also available testing depletion of synthetic peptides containing either cysteine (SPCC) or lysine (SPCL), showed 3.1% SPCC depletion and 100% SPCL depletion (Rijk, 2016). The conflicting results within the DPRA study (3.1% SPCC depletion compared to 100% SPCL depletion) are questionable and may indicate a false positive consideration of the DPRA, therefore the study was disregarded.

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

A key study for the assessment of skin sensitization to Butanedioic acid, sulfo-, 4-C16-18 (even numbered)-alkyl esters, disodium salts was done in the Mouse (Local Lymph Node Assay).Test item concentrations selected for the main study were based on the results of a pre-screen test.In the main study, three experimental groups of five female CBA/J mice were treated with test item concentrations of 10, 25 or 50% w/w on three consecutive days, by open application on the ears. Five vehicle control animals were similarly treated, but with the vehicle alone (Propylene glycol).Three days after the last exposure, all animals were injected with 3H-methyl thymidine and after five hours the draining (auricular) lymph nodes were excised and pooled for each animal. After precipitating the DNA of the lymph node cells, radioactivity measurements were performed. The activity was expressed as the number of disintegrations per minute (DPM) and a stimulation index (SI) was subsequently calculated for each group.No erythema was observed in any of the animals.All auricular lymph nodes of the animals of the experimental and control groups were considered normal in size. No macroscopic abnormalities of the surrounding area were noted for any of the animals.Mean DPM/animal values for the experimental groups treated with test item concentrations 10, 25 and 50% were 1019, 1496 and 1329 DPM, respectively. The mean DPM/animal value for the vehicle control group was 943 DPM. The SI values calculated for the test item concentrations 10, 25 and 50% were 1.1, 1.6 and 1.4, respectively.Since there was no indication that the test item elicited a SI ≥ 3 when tested up to 50%, Butanedioic acid, sulfo-, 4-C16-18 (even numbered)-alkyl esters, disodium salts was not considered to be a skin sensitizer.

A Direct Peptide Reactivity Assay (DPRA) with Butanedioic acid, sulfo-, 4-C16-18 (even numbered)-alkyl esters, disodium salts was available testing depletion of synthetic peptides containing either cysteine (SPCC) or lysine (SPCL). Following 24 hours of incubation, the relative peptide concentration was determined by High-Performance Liquid Chromatography (HPLC) with gradient elution and photodiode array (PDA) detection at 220 nm and 258 nm.Water was found to be the most appropriate solvent to dissolve Butanedioic acid, sulfo-, 4-C16-18 (even numbered)-alkyl esters, disodium salts, and was therefore used in this DPRA study. However, since precipitation was observed upon addition of the test chemical to the SPCC and SPCL peptide solutions, one cannot be sure how much test item remained in the solution to react with the peptide.In the cysteine reactivity assay Butanedioic acid, sulfo-, 4-C16-18 (even numbered)-alkyl esters, disodium salts showed 3.1% SPCC depletion, and in the lysine reactivity assay Butanedioic acid, sulfo-, 4-C16-18 (even numbered)-alkyl esters, disodium salts showed 100% SPCL depletion. The mean of the SPCC and SPCL depletion was 51.5%, therefore, Butanedioic acid, sulfo-, 4-C16-18 (even numbered)-alkyl esters, disodium salts was considered to be positive in the DPRA.The mean Percent SPCC Depletion for the positive control cinnamic aldehyde was 75.7% ± 1.5%; this was within the acceptance range of 60.8-100%.The mean Percent SPCL Depletion for positive control cinnamic aldehyde was 39.1% ± 1.7%, which was borderline with the acceptance range of 40.2 -69%.

The conflicting results within the DPRA study (3.1% SPCC depletion compared to 100% SPCL depletion) are questionable and may indicate a false positive consideration of the DPRA, therefore the study was disregarded. In a study on 45 sensitizing chemicals, the majority (27/45) were shown to be reactive towards both cysteine and lysine peptides; only 11 sensitizers were exclusively reactive toward cysteine and nearly all of them were pre-/pro-haptens. None of them were reported to be exclusively reactive to lysine (Troutman et al.2011).

In a classification tree model study for allergic potency screening tested on 81 substances, sensitivity and specificity for the DPRA model were 89 and 90%, respectively, resulting in 89% accuracy (Geberick et al., 2007). In the DPRA ECVAM Validation Study Report (2012), sensitivity and specificity of the DPRA versus LLNA were 79.5 and 91.7%, respectively, resulting in an accuracy of 84.1% (n = 63 compounds tested). In the same report, the predictive capacity of the DPRA by P&G was also reported (sensitivity and specificity were 87 and 83%, respectively; accuracy = 86%; n = 133 compounds tested). Various non-sensitizers were reported in the DPRA as sensitizers (low to high reactivity), indicating that the model is not always specific and may lead to false positive results (ECVAM, 2012). The result of the DPRA study with current test item is most probably a false positive finding, as none of the sulfosuccinate surfactants has even been detected as sensitizing molecules.

The DPRA is partial replacement in chemico test method designed to be part of a non-animal battery or integrated testing strategy for assessing the skin sensitisation potential of chemicals. It cannot be interpreted as a stand-alone study, however it should be interpreted in a weight-of-evidence approach. The LLNA is the first choice of in vivo testing; the model was initiated before the changes onin vitro testing came into force and meets the requirements set out in REACH Article 13(3), first subparagraph, and Article 13(4), and is considered appropriate to address this endpoint.

References:

ECVAM Direct Peptide Reactivity Assay (DPRA) Validation Study Report. January 2012. EUROPEAN COMMISSION - JOINT RESEARCH CENTRE. Institute for Health and Consumer Protection. European Union Reference Laboratory for Alternative Methods to Animal Testing (ECVAM).

Gerberick FG, Vassallo JD,Foertsch LM, Price BB, Chaney JG, Lepoittevin JP. Quantification of Chemical Peptide Reactivity for Screening Contact Allergens: A Classification Tree Model Approach. TOXICOLOGICAL SCIENCES 97(2), 417–427 (2007). doi:10.1093/toxsci/kfm064

Troutman JA, Foertsch LM, Kern PS, Dai HJ, Quijano M, Dobson RLM, Lalko JF, Lepoittevin JP, Gerberick GF. The Incorporation of Lysine into the Peroxidase Peptide Reactivity Assay for Skin Sensitization Assessments. TOXICOLOGICAL SCIENCES 122(2), 422–436 (2011).

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

Based on these results, Butanedioic acid, sulfo-, 4-C16-18 (even numbered)-alkyl esters, disodium salts would not be regarded as a skin sensitizer according to the recommendations made in the test guidelines. The test item does not have to be classified and has no obligatory labelling requirement for sensitization by skin contact according to the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) of the United Nations (2015) (including all amendments) and the Regulation (EC) No 1272/2008 on classification, labeling and packaging of items and mixtures (including all amendments).