Dimethoxydiphenylsilane

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Genotoxicity in vitro:
Ames test (OECD 471, GLP): positive in strain TA 1535 without metabolic activation
Ames test (OECD 471, GLP): negative in all strains including TA 1535
Ames test (similar to OECD 471): negative in all strains including TA 1535

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Genetic toxicity in vivo

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Genetic toxicity in vitro:

Three reliable Ames assays are available for assessment of genetic toxicity of dimethoxydiphenylsilane.

In an Ames assay, conducted according to OECD TG 471 (adopted 1997) and in compliance with GLP (SafePharm Laboratories Ltd, 2002), Salmonella typhimurium strains TA 1535, TA 1537, TA 98 and TA 100 as well as E. coli WP2 were treated with the registered substance up to 5000 µg/plate dimethoxydiphenylsilane (CAS 6843-66-9) in the absence and presence of a metabolic activation system. No increase in revertants/plate was detected at any concentration up to cytotoxic concentration, with metabolic activation. Without metabolic activation also no increase in revertants/plate was observed in all strains except TA 1535. Incubation of TA 1535 led to a reproducible increase in revertants/plate by the factor of 2-3 over several concentrations, although a clear dose-response effect was not shown, as a plateau was reached very early. Cytotoxicity was not observed. Appropriate solvent and positive controls were included and gave expected results.

In a second reliable Ames assay, also conducted according OECD TG 471 (adopted 1983) and in compliance with GLP (Hüls AG, 1995e) Salmonella typhimurium strains TA 1535, TA 1537, TA 98 and TA 100 were treated with up to 5000 µg/plate dimethoxydiphenylsilane (CAS 6843-66-9) in the absence and presence of a metabolic activation system. No increase in revertants/plate was detected at any concentration up to cytotoxic concentration, with or without metabolic activation, in either the initial plate incorporation assay or the repeat pre-incubation test. Cytotoxicity was observed after incubation with 5000 μg/plate in strains S. typhimurium TA 1535 and S. typhimurium TA 1537. Appropriate solvent and positive controls were included and gave expected results.

Similar results were observed in a third Ames test, conducted similarly to OECD TG 471 (Dow Corning Corporation, 1977). Salmonella typhimurium strains TA 1535, TA 1537, TA 1538, TA 98 and TA 100 treated with up to 500 µg/plate dimethoxydiphenylsilane (CAS 6843-66-9) in the absence and presence of a metabolic activation system. No increase in revertants/plate was detected at any concentration, with and without metabolic activation.

A positive result was found in one out of the three Ames tests with the registered substance. In the Ames test with the positive result, only Salmonella typhimurium strain TA 1535 without metabolic activation, resulted in a stitistically significant increase in the number of revertants, but a clear dose-response effect was not observed as a plateau was reached very early. Also, no effects were found in the other two reliable studies. Thus, it is concluded that dimethoxydiphenylsilane (CAS 6843-66-9) is negative for mutagenicity to bacteria under the applied test conditions.

Justification for classification or non-classification

The available data on genetic toxicity in bacteria of the registered substance do not meet the criteria for classification according to Regulation 1272/2008 or EU Directive 67/548/EEC. According to Annex VII no further testing is required.