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 in all strains tested (OECD TG 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
Endpoint conclusion:
no adverse effect observed (negative)

Genetic toxicity in vivo

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

Information is available on in vitro gene mutation in bacteria as well as on 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 471 with no or 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. No background toxicity was observes, no increase in revertant mutations was seen at any concentration.

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 3000 microgram/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. They 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 3000 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.


Justification for classification or non-classification

The available information for the substance indicates that when tested in vitro, 2,4,6,8,10-pentamethylcyclopentasiloxane (CAS number 6166 -86 -5) 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 according to Regulation (EC) No 1272/2008.