Registration Dossier

Administrative data

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Gene mutation (Bacterial reverse mutation assay / Ames test): negative with and without activation S. typhimurium TA 1535, TA 1537, TA 98 and TA 100, E. coli WP2 uvr A pKM 101 and WP2 pKM101 (OECD TG 471) (Dow Corning Corporation (1995a).
Cytogenicity in mammalian cells: negative in Chinese hamster V79 cells (OECD TG 473) (Hofman-Hüther, H. (2013).
Mutagenicity in mammalian cells: negative in L5178Y mouse lymphoma cells (OECD TG 476) (DCC (1995b).

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (negative)

Genetic toxicity in vivo

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

The selected in vitro studies are the only available cytogenicity and bacterial and mammalian mutagenicity studies for the substance. The bacterial study was conducted according to a protocol that is equivalent to an appropriate OECD guideline; the studies in mammalian cells were conducted according to appropriate OECD guidelines. All studies were conducted in compliance with GLP.

Information is available for silsesquioxanes, phenyl from reliable in vitro studies on mutagenicity to bacterial and mammalian cells, and cytogenicity to mammalian cells. The results of all the studies were in agreement: no evidence for mutagenicity was obtained. It is therefore considered that in vivo testing is not required.

Silsesquioxanes, Phenyl has been tested for mutagenicity to bacteria, in a study which was conducted according to a protocol that was similar to OECD 471, and in compliance with GLP (Dow Corning Corporation (1995a). No evidence of a test substance related increase in the number of revertants was observed with or without activation in the experiment, which tested Salmonella typhimurium strains TA 1535, TA 1537, TA 98 and TA 100, and E. coli WP2 uvr A pKM 101 and WP2 pKM101up to limit concentrations. Appropriate positive and solvent controls were included and gave expected results. It is concluded that the test substance is negative for mutagenicity to bacteria under the conditions of the test.

Information on the potential of Silsesquioxanes, Phenyl to cause structural or numerical damage to chromosomes is available from a reliable study which was conducted according to OECD 473 (1997) and in compliance with GLP (Hofman-Hüther, H. (2013)). No evidence for a potential to cause structural or numerical damage to chromosomes was observed with or without activation when tested up to limit concentrations in Chinese hamster V79 cells. Appropriate solvent and positive controls were included and gave expected results. It is concluded that the test substance is negative for cytogenicity to mammalian cells under the conditions of the test.

Silsesquioxanes, Phenyl was tested in a L5178Y/TK+/- mouse lymphoma mutagenesis assay, in a study which was conducted according to OECD 476 and in compliance with GLP (DCC 1995b). No evidence of a test substance related increase in mutant frequency was detected at any concentration in the presence or absence of metabolic activation. Appropriate solvent and positive controls were concluded and gave expected results. It is concluded that the test substance is negative for the induction of mutation in L5178Y cells under the conditions of the test.


Justification for classification or non-classification

Based on the available in vitro data, Silsesquioxanes, Phenyl does not require classification for mutagenicity according to Regulation (EC) No 1272/2008.