Oleic acid, compound with N-(2-aminoethyl)ethane-1,2-diamine

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

The study was conducted to assess the skin sensitizing potential of the test item Oleic acid, compound with N-(2-aminoethyl)ethane-1,2-diamine using the Local Lymph Node Assay (LLNA) in mice according to OECD 442B guideline and GLP (Bioassay, 2012). Test item solutions at different concentrations were prepared in the vehicle acetone: olive oil (AOO; 4:1, v/v). The local lymph node assay is recommended by international test guidelines (e.g. OECD) as an animal test for predicting skin sensitization in humans and provides a rational basis for risk assessment. The basic principle underlying the LLNA is that sensitizers induce a primary proliferation of lymphocytes in the lymph node draining the application site. The ratio of proliferation in test item treated groups compared to that in vehicle controls is termed the Stimulation Index (S.I.). BrdU labeling is used to measure cell proliferation. For this purpose a local lymph node assay was performed using test item concentrations of 0.1, 0.25 and 0.5% (w/w; weight per weight). Doses based on previously performed four pretests in the same animal strain in which 24 mice in total were used. Signs of systemic toxicity were not observed in the pre-tests. At the tested concentrations of 1, 2.5, 5, 10, 25, 50 and 100% the animals showed signs of local irritation as confirmed by the ear weight measurements. All animals in these dose groups showed exceeded thresholds with increased ear weights > 25%. Animals in these dose groups also showed ear swellings > 25%. In addition erythema, swelling and hardening of the ears, incrustations, scaling and test item residues were observed in dose group 50 and 100%. In dose group 10 and 25% erythema, ear swelling and test item residues were noted. Erythema, ear swelling and scaling and incrustations were observed in dose group 2.5 and 5%. In dose group 1% erythema, scaling and incrustations were noted, in dose group 0.5% scaling was observed. The vehicle animals were in a normal range concerning ear weight measurements and ear swelling. Animals in dose group 0.5% didn`t show increased ear weights > 25%. One animal in dose group 0.5% revealed ear swellings > 25%. Due to the fact that concurrent ear weight measurements were below the threshold and that the ear thickness value (27%) in one animal only marginally exceeded the threshold of 25% (and in which error of measurement is possible to some extent), the following dose levels were selected for the main study: 0.5%, 0.25% and 0.1% (w/w) in acetone:olive oil (4:1,v/v). The decision was made after consulting the sponsor. In the main study the animals did not show any relevant signs of systemic toxicity during the course of the study and no cases of mortality were observed. In the high dose group (0.5%) scaling was observed at the last day of observation. A biologically relevant increase in ear weights was not observed in any treated group in comparison to the vehicle control group. In dose group 0.5% ear weight measurement reached statistically significance. The cut-off-value for a positive response regarding the ear weight index of 1.25 was not exceeded in any dose group. A test item is regarded as a sensitizer in the LLNA if exposure to one or more test item concentration results in a 1.6-fold or greater increase in incorporation of BrdU compared with concurrent controls, as indicated by the Stimulation Index (S.I.). The estimated test item concentration required to produce a S.I. of 1.6 is referred to as the EC1.6 value.

In this study Stimulation Indices (S.I.) of 1.2, 1.0 and 1.4 were determined with the test item at concentrations of 0.1, 0.25 and 0.5 % (w/w) in AOO. An unusual dose response was observed. An EC1.6 value could not be determined as all S.I.s obtained were below the threshold of 1.6. A statistically significant or biologically relevant increase in BrdU value and also in lymph node weight was not observed in any of the tested dose groups in comparison to the vehicle control group. In dose group 0.5% lymph node cell count reached statistically significance without biological relevance. No biological relevance or statistical significance was observed in the other test groups in this regard. Furthermore, the cutoff-value for a positive response regarding the lymph node cell count index of 1.55 reported for BALB/c mice (see Ref. 8) was not exceeded in any of the tested dose groups. As expected, a statistical and biological relevant increase in BrdU labelling, lymph node weight and lymph node cell count was determined in the positive control. Ear weight measurement revealed a statistical significance without reaching biological relevance. The test item Oleic acid, compound with N-(2-aminoethyl)ethane-1,2-diamine was thus not a skin sensitiser under the test conditions of this study.

Migrated from Short description of key information:
LLNA (Bioassay, 2012): not sensitizing

Justification for classification or non-classification

Based on the data received from the LLNA, no classification as skin sensitizer according to EU Directive 67/548/EEC and EU classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No 1272/2008 is warranted.