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Key value for chemical safety assessment

Additional information

For this endpoint 3 in vitro tests, performed similar to OECD test guidelines, were selected as key studies:

- One Bacterial Reverse Mutation Assays (Ames test). The results of the tests conducted on the compound in the absence and in the presence of a metabolic activation system were all negative. The test compound, S-154 Lot QH-30701 B0-78-82, did not demonstrate genetic activity in any of the assays conducted in this evaluation and was considered not mutagenic under these test conditions.

- A Sister Chromatid Exchange (SCE) assay in mammalian cells and In vitro mammalian Chromosome Aberration test. Chromosome aberration results were negative at all dose levels both with and without the enzyme activation system. No significant increases were observed in the frequency of cells with aberrations, and so the compound is concluded to be non-clastogenic. SCE frequencies also failed to increase with dose, both with and without the activation system, and so the test compound was clearly negative in this assay. In conclusion, Phosflex 51B failed to induce visible chromosome damage under the conditions of these assays.

- An vitro Mammalian Cell Gene Mutation Test. The test compound, Phosflex 51B, did not induce an increase in mutations at the TK locus in L5178Y mouse lymphoma cells at concentrations of 0.975 to 125.0 nl/ml with and without activation. The concentration of 125 nl/ml was highly toxic and insufficient survivors were obtained at 250 nl/ml to perform the assay. Therefore the test compound is considered to be inactive in this Mouse Lymphoma Forward Mutation Assay.

The following 2 in vitro tests are considered supporting studies:

- In vitro Mammalian Cell Gene Mutation Test (similar to OECD 476): S-154 BO-78-86 was not mutagenic in the mouse lymphoma L5178Y cells when tested under the conditions outlined in this report.

- In vitro Mammalian Cell Transformation assay: The test material, Phosflex 51B, did not induce a significant increase in transformed foci over the applied concentration range of 0.00125 ul/ml to 0.02 ul/ml. This concentration range corresponded to approximately 90% to 52% survival in the cytotoxicity test. Therefore, the test material is considered to be inactive in this Balb/3T3 In Vitro Transformation Assay.


Short description of key information:
- Gene mutation in bacteria (Bacterial Reverse Mutation Assay/Ames) (similar to OECD 471): not mutagenic.
- In vitro cytogenicity test (Sister Chromatid Exchange (SCE) assay in mammalian cells and In vitro Mammalian Chromosome Aberration test) (similar to OECD 479): negative.
- In vitro Mammalian Cell Gene Mutation Test (Mouse lymphoma assay) (similar to OECD 476): not mutagenic.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

In all available key and supporting studies t-BuTTP did not show any genotoxic potential. Therefore, it can be concluded that the substance is not mutagenic and therefore does not need to be classified for mutagenicity according to the criteria outlined in 1272/2008/EC (CLP/EU-GHS).