hydrolysis products of 3-(triethoxysilyl)propan-1-amine

Endpoint summary

Additional information

Genetic toxicity: in-vitro

The UVCB substance "hydrolysis products of 3-(triethoxysilyl)propan-1-amine" is a complex reaction product obtained from hydrolysis of 3-(triethoxysilyl)propan-1-amine in water. The test substance consists of monomers, dimers and polymers of siloxanes as well as ethanol. The concentration range of each constituent depends on the manufacturing condition (e.g. the ratio of 3-(triethoxysilyl) propan-1-amine and water). Typical concentrations of the test substance obtained from hydrolysis of an aqueous solution of 8% 3-(triethoxysilyl)propan-1-amine are described below: ca. 0.52% (w/w) 3-aminopropylsilanetriol (monomer, CAS 58160-99-9), ca. 0.7% (w/w) 1,3-bis(3-aminopropyl)disiloxane-1,1,3,3-terol (dimer), ca. 3% (w/w) hydrolysed polymers of 3-aminopropyltriethoxysilane, ca. 4.99% (w/w) ethanol (CAS 64-17-5) and ca. 90.79% water.

Hydrolysis product of 3-(triethoxysilyl)propan-1-amine (8%) was chosen for testing genetic toxicity in-vitro as this concentration represents a typical concentration in the manufacturing process.

A gene mutation assay in bacteria (Ames test) was conducted with hydrolysis product of 3-(triethoxysilyl)propan-1-amine (8%) in the Salmonella typhimurium strains TA 1535, TA 1537, TA 98, TA 100 and TA102 according to OECD 471 (Flügge, 2012). Based on a preliminary cytotoxicity test, concentrations ranging from 10 to 3160 µg/plate for S. typhimurium strains were selected for treatment in the presence and absence of a metabolic activation system in two independent experiments. No increase in the mean revertant number of colonies was observed at any of the concentrations tested in both experiments with and without metabolic activation. However, the test substance caused cytotoxicity, indicated as scarce background lawn and reduction of the number of revertants at the top concentration of 3160 µg/plate in all test strains both in the presence and absence of metabolic activation.

Based on the result, the test substance was not considered to be mutagenic in the Ames test with and without metabolic activation.

According to OECD 487, the potential of hydrolysis product of 3-(triethoxysilyl)propan-1-amine (8%) to induce chromosomal aberrations was tested in cultured Chinese hamster ovary (CHO-K1) cells using the micronucleus test (Flügge, 2012). Based on a preliminary cytotoxicity test, CHO-K1 cells were exposed to test substance at concentrations from 625 to 5000 µg/mL. No increase in the number of micronuclei was observed in the experiments with short-term treatment (4 h) in the presence or absence of metabolic activation. Because of the negative results of the short-term treatment, a confirmatory testing with extended treatment (20 h) was performed without metabolic activation. In addition, the short-term treatment with metabolic activation was repeated. In the confirmatory tests, the test substance did also not induce micronucleus formation in CHO-K1 cells. In both experiments, no signs of cytotoxicity were noted up to the top concentration of 5000 µg/mL without and with metabolic activation. Therefore, the test substance was not considered to be clastogenic to CHO-K1 cells under the conditions of the test.

Hydrolysis product of 3-(triethoxysilyl)propan-1-amine (8%) was also tested for its potential to cause gene mutations in the mouse lymphoma assay according to OECD 476 (Flügge, 2012). Based on a preliminary cytotoxicity test, mouse lymphoma L5178Y cells were treated with the test substance at concentration from 312.5 to 5000 µg/mL both with and without metabolic activation. The potential mutagenicity of the test substance on the thymidine kinase locus was investigated after 3 h. After short-term treatment, no increase in mutant frequency was observed with and without metabolic activation. Based on the negative result, a confirmatory gene mutation assay was performed with extended treatment (24 h) in absence of metabolic activation. Moreover, the short-term treatment was repeated with metabolic activation. In the confirmatory tests, the test substance showed also no increase in mutant frequency. No signs of cytotoxicity (decreased survival) were noted in the presence and absence of metabolic activation up to the top concentration of 5000 µg/mL in both experiments.The test substance is therefore not considered to be mutagenic under the conditions of the test.

Hydrolysis product of 3-(triethoxysilyl) propan-1-amine (8%) showed no evidence of a clastogenic and mutagenic potential with and without metabolic activation in in-vitro test systems.

Justification for selection of genetic toxicity endpoint
No study was selected, since all three in-vitro studies were negative.

Short description of key information:
In-vitro:
Gene mutation (bacterial reverse mutation assay / Ames test): S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102: negative with and without metabolic activation (according to OECD 471)
Chromosome aberration (in-vitro mammalian cell micronucleus test): negative with cultured Chinese hamster ovary (CHO-K1) cells with and without metabolic activation (according to OECD 487)
Gene mutation (in-vitro mammalian cell gene mutation assay): negative with mouse lymphoma L5178Y cells in the mutant frequency at the thymidine kinase locus with and without metabolic activation (according to OECD 476)

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

The available data on genetic toxicity of the test substance do not meet the criteria for classification according to Regulation (EC) No 1272/2008 and are therefore conclusive but not sufficient for classification.