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Description of key information

Key value for chemical safety assessment

Skin sensitisation

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

A QSAR program calculated a positive sensitisation potential of the test substance. The LLNA study however did not indicate a potential for sensitisation.


 


The sensitising potential of the test substance was evaluated according to an experimental study according to OECD Guideline 429 using the radioactive Murine Local Lymph Node Assay.
Groups of 5 female CBA/J mice each were treated with 10%, 25% and 50% w/w preparations of the test substance in 1% aqueous Pluronic® or with the vehicle alone. The study used 3 test groups and 1 control group. Each test animal was applied with 25 μL per ear of the respective test-substance preparation to the dorsum of both ears for three consecutive days. The control group was treated with 25 μL per ear of the vehicle alone.
Three days after the last application the mice were injected intravenously with 20 μCi of 3Hthymidine in 250 μL of sterile saline into a tail vein. About 5 hours after the 3H-thymidine injection, the mice were sacrificed and the auricular lymph nodes were removed. Lymph node response was evaluated by measuring the cellular content and 3H-thymidine incorporation (indicator of cell proliferation) as well as the weight of each animal’s pooled lymph nodes.
Moreover, a defined area with a diameter of 0.8 cm was punched out of the apical part of each ear and for each animal the weight of the pooled punches was determined in order to obtain an indication of possible skin irritation.


No signs of systemic toxicity were noticed.
When applied as 10%, 25% and 50% preparations in 1% aqueous Pluronic®, the test substance induced an increase in the auricular lymph node cell counts below 1.5 fold of the control value (= stimulation index (SI) ≥ 1.5) without concentration dependence. There was a slight increase in lymph node weights without concentration dependence, as well.
Concomitantly, the 25% concentration caused a borderline increase of 3H-thymidine incorporation into the cells above the cut off stimulation index of 3. The 50% and 10% concentration failed to reach the cut-off value (no increase above the stimulation index of 3).


However, increases in cell counts, 3H-thymidine incorporation and lymph node weights were statistically significant at all concentrations without concentration dependence. The 50% test-substance preparation caused a statistically significant increase in ear weights. No relevant increases in ear weights were observed at the concentrations 10% and 25%.
As the SI for 3H-thymidine incorporation at the 25% concentration lies at the border of biological relevance, whereas the increase of cell counts was not biologically relevant and because there was no concentration response relation, the 3H-thymidine incorporation is not considered to indicate a skin sensitization reaction.



Thus it is concluded that the test substance does not show a skin sensitizing effect in the Murine Local Lymph Node Assay under the test conditions chosen.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available (further information necessary)

Justification for classification or non-classification

The LLNA study indicated absence of a sensitisation potential. Therefore the substance is not classified for this endpoint in accordance to the CLP Regulation (EC) No 1272/2008.