Morpholine, 4-[(triethoxysilyl)methyl]-

Endpoint summary

Additional information

(N-Morpholinomethyl)triethoxysilane was investigated for its potential to induce gene mutations according to the plate incorporation and the pre-incubation test using Salmonella typhimurium strains TA 98, TA 100, TA 1535, TA 1537 and TA 102. The study followed the OECD Guideline 471 (1997). The assay was performed in two independent experiments both with and without metabolic activation. The concentrations covered the range from 31.6 to 5000 µg/plate. No relevant toxic effects occurred in the plate incorporation test. In the pre-incubation test toxic effects of the test item were observed in tester strain TA 1535 at a dose of 2500 µg/plate and higher (with metabolic activation) and in tester strains TA 1537 and TA 102 at a dose of 5000 µg/plate (with metabolic activation). No substantial increase in revertant colony numbers were observed in any experiment with the test substance. Appropriate reference mutagens were used as positive controls. They showed a distinct increase in induced revertant colonies. In conclusion, it can be stated that during the described mutagenicity test and under the experimental conditions reported, the test article did not induce gene mutations by base pair changes or frameshifts in the genome of the strains used. Therefore SLM 449020 is considered to be non-mutagenic in this Salmonella typhimurium reverse mutation assay.

In a second experiment the test item (N-Morpholiomethyl)triethoxysilane was investigated for a possible potential to induce structural chromosomal aberrations in V79 cells of the Chinese hamster in vitro in the absence and the presence of metabolic activation with S9 homogneate. The positive and the control incubations were within historical ranges. In the absence of metabolic activation the concentrations 2500, 5000 µg/mL revealed an increase of aberrant cells above the historical negative control data. In the presence of metabolic activation the number of aberrant cells stayed within the historical negative control data. It is concluded that the test item, under the conditions of test, showed evidence of clastogenic activity.

(N-Morpholinomethyl)triethoxysilane has been assessed for its potential mutagenicity on the thymidine kinase, TK+/-, locus of the L5178Y mouse lymphoma cell line, according to OECD Test Guideline 490 and in compliance with GLP. For the short-term experiments, the solved test item was incubated with cells for 4 hours, with and without metabolic activation. The test item was investigated at the following concentrations: 0.75; 1.0; 1.75 and 2.0 μL/mL (without S9) and 0.75; 1.0; 1.5 and 2 μL/mL (with S9). No precipitation of the solved test item was noted in the experiments. No growth inhibition was observed in any experiments. No biologically relevant increase of mutants was found in any experiments. The global evaluation factor (GEF) was not exceeded by the induced mutant frequency. It is concluded that the test substance is negative for mutagenicity to mammalian cells under the conditions of the test (Eurofins, 2021).

Since the in vitro experiments were inconclusive for a final decision, (N-Morpholinomethyl)triethoxysilan was investigated for its potential to induce micronuclei in polychromatic erythrocytes (PCE) in the bone marrrow of the mouse.

In comparison to the corresponding vehicle controls there was not a biolgically relevant enhancement in the frequency of the detected micronuclei at any preparation interval after administration of the test item and with any dose level used. The positive control worked as expected. In a separate study the bioavailabilty of (N-Morpholinomethyl)triethoxysilan was examined. Overall significant mean levels of the test item were found in blood and plasma as early as 1 hour after application. This indicates that after oral administration the test item was rapidly absorbed in significant amounts.

Dose and formulation of the radiolabeled test item in this study were comparable to this study. Therefore, an adequate exposure of plasma and bone marrow to (N-Morpholinomethyl)triethoxysilan and/or its metabolites in the micronucleus assay can be assumed. In conclusion, it can be stated that during the study described and under the experimental conditions reported, the test item did not induce micronuclei.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

(N-Morpholinomethyl)triethoxysilane is not classified for genetic toxicity as the positive clastogenic response in the in vitro chromosomal aberration test was not confirmed by the in vivo micronucleus test and the Ames test revealed no mutagenic activity.