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Administrative data

Key value for chemical safety assessment

Additional information

Valid information is available for in vitro gene mutation in bacteria as well as for in vitro cytogenicity and mutagenicity in mammalian cells.

 

The test substance was found to be negative in a well-conducted bacterial mutation assay according to OECD protocol with no or only minor deviations. The strains tested were S. typhimurium TA 1535, TA 1537, TA 98 and TA 100, and E. coli WP2 uvrA, with and without metabolic activation, at dose levels up to 5000 µg/plate. Positive and vehicle controls gave results within the range of historical controls.

The test substance was found to be negative in a well-conducted chromosome aberration test in human lymphocytes. In two independent experiments, with and without metabolic activation, at dose levels up to 2400µg/ml (approx 10 mM), no cytotoxicity, no statistically significant or a biologically relevant increase in the number of cells carrying structural chromosomal aberrations or an increase in polyploid metaphases was seen compared to the control cultures.

Appropriate mutagens were used as positive controls. These induced statistically significant increases (p < 0.05) in cells with structural chromosome aberrations.

The test substance was found to be negative in a well-conducted mammalian mutagenicity test in mouse lymphoma L5178Y cells. In two independent experiments, with and without metabolic activation, at dose levels up to 2400 µg /ml (approx 10 mM), no cytotoxicity nor statistically significant or a biologically relevant increase in the number of mutant colonies was observed. Positive and vehicle controls gave results within the range of historical controls.


Short description of key information:
In vitro:
Gene mutation (Bacterial reverse mutation assay / Ames test): Negative with and without activation in all strains tested (OECD 471)
Cytogenicity in mammalian cells: Negative with and without activation in cultured human lymphocytes (OECD 473)
Mutagenicity in mammalian cells: Negative with and without activation in L5178Y mouse lymphoma cells (OECD TG 476)

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

The available information for the substance indicates that when tested in vitro, 2,4,6,8 -tetramethylcyclotetrasiloxane (CAS number 2370 -88 -9) does not induce mutations in bacterial or mammalian cells, nor chromosome aberrations in mammalian cells. There is no justification from in vitro results for testing in vivo. Therefore it is considered that classification for mutagenicity is not required.