Reaction mass of 1-hydroxydecan-3-one and 3-(hydroxymethyl)nonan-2-one and nonan-2-one

Endpoint summary

Description of key information

Reactive in DPRA (OECD TG 442C, GLP)

Positive in KeratinoSens (OECD TG 442D, GLP)

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

In vitro: DPRA

In a GLP-compliant OECD guideline 442C study, the Direct Peptide Reactivity Assay (DPRA) was used to assess the reactivity and sensitizing potential of the test substance. The test substance was dissolved in isopropanol, based on the results of the pre-experiments. For the 100 mM stock solution of the test item no turbidity or precipitation was observed when diluted with the cysteine peptide solution and the lysine peptide solution, respectively. After the 24 h ± 2 h incubation period but prior to the HPLC analysis samples were inspected for precipitation, turbidity or phase separation. No precipitation, turbidity or phase separation was observed for any of the samples. No co-elution of the test item with the peptide peaks was observed. Sensitising potential of the test item was predicted from the mean peptide depletion of both analysed peptides (cysteine and lysine) by comparing the peptide concentration of the test item treated samples to the corresponding reference control. The 100 mM stock solution of the test item showed low reactivity towards the synthetic peptides. The mean depletion of both peptides was > 6.38% (19.50%). Based on the prediction model 1, the substance was positive in the DPRA and was classified in the “low reactivity class”.

In vitro: KeratinoSens

A KeratinoSensTM assay was performed with the substance according to OECD 442D and in accordance with GLP principles. Two valid independent experiments were performed. The cells in these experiments were incubated with the test item in a concentration range of 0.98 – 2000 µM (2-fold dilution steps) for 48 hours at 37°C. After exposure cells were lysed and luciferase activity was assessed by luminescence measurement. In the first experiment, a max luciferase activity (Imax) induction of 12.09 was determined at a test item concentration of 500 μM. The corresponding cell viability was 57.6%. The lowest tested concentration with a significant luciferase induction >1.5 (3.86) was found to be 250 μM. The corresponding cell viability was >70% (70.4%). The calculated EC1.5 was <1000 μM (133.49 μM). In the second experiment, a max luciferase activity (Imax) induction of 33.41 was determined at a test item concentration of 1000 μM. The corresponding cell viability was 9.3%. The lowest tested concentration with a significant luciferase induction >1.5 (1.74) was found to be 125 μM. The corresponding cell viability was >70% (102.1%). The calculated EC1.5 was <1000 μM (101.64 μM). A dose response for luciferase activity induction was observed for each individual run as well as for an overall luciferase activity induction. Under the condition of this study the test item is considered positive.

Justification for classification or non-classification

The substance is a skin sensitiser based on two positive in vitro skin sensitisation tests covering two key events of the Adverse Outcome Pathway and therefore the substance needs to be classified for skin sensitisation as Skin Sens 1: H317 according to EU CLP (EC 1272/2008 and its amendments).