Phosphonic acid, P-(3-silylpropyl)-, Si,Si,Si-tris(mixed ethoxy and methoxy) derivs., mixed Et and Me diesters

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

Data from the structurally related substance " Silsesquioxanes, 3-phosphonopropyl, Et Me esters, sodium salts" (CAS 225375-65-5) was used to assess the aquatic toxicity of the registration item ( Phosphonic acid, P-(3-silylpropyl)-, Si,Si,Si-tris(mixed ethoxy and methoxy) derivs., mixed Et and Me diesters; CAS 1079258-99-3):

The skin sensitizing potential of the read across substance Silicophosphonat was assessed using the radioactive Murine Local Lymph Node Assay (OECD 429 guideline and GLP; BASF, 2008). The assay simulates the induction phase for skin sensitization in mice. It determines the response of the auricular lymph nodes on repeated application of the test substance to the dorsal skin of the ears. Groups of 5 female CBA/J mice each were treated with 10%, 30% and 50% w/w preparations of the test substance in propylene glycol 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 3H-thymidine 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 test group 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% preparation in propylene glycol, the test substance did not induce relevant changes in the auricular lymph node cell counts or ³H-thymidine incorporation. The 30% and 50% test substance preparations caused slight but not concentration related increases in cellularity and 3H-thymidine incorporation into the lymph node cells, which failed to reach the cut off stimulation indices (increase to 1.5 or 3 fold or above of control value = stimulation index (SI) ≥ 1.5 or 3, respectively) and thus lie below the threshold of immunologic relevance. In addition there was no relevant increase in lymph node weights.

The 10%, 30% and 50% test-substance preparations did not cause an increase in ear weights as indication of ear skin irritation when compared to the vehicle control. Thus it is concluded that the read across substance Silicophosphonat does not show a skin sensitizing effect in the Murine Local Lymph Node Assay under the test conditions chosen.

Migrated from Short description of key information:
LLNA (read across): not sensitising

Justification for classification or non-classification

Based on the available read across data, no classification for skin sensitization is warranted.