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Key value for chemical safety assessment

Additional information

MS-Silane is a UVCB comprised of 13 constituents. They are a structurally similar group of silanes with varying levels of carbon, oxygen and chlorine substitution.

 

Reliable data are available for four of the constituents of MS-Silane. The in vitro and in vivo genetox testing was conducted for the chlorinated form of the compounds and all tests conducted were found to be negative for genetic effects (see Table 1).

Table 1. Available Genetic Toxicity Data for MS-Silane Constituents

Constituent % in MS- Silane In vitro Bacterial Test / Result In vitro Mammalian Gene Mutation Test / Result In vitro Mammalian Chrom Ab Test / Result In Vivo Test / Result
75-78-5 dichloro(dimethyl)silane 20-35% OECD 471 / Negative OECD 476 / Negative OECD 473 / Negative Rodent Bone Marrow Cytogenetic Assay / negative
75-77-4 chlorotrimethylsilane 0-5% OECD 471 / Negative OECD 476 / Negative OECD 473 / Negative OECD 475 / Negative
10026-04-7 tetrachlorosilane 0-15% OECD 471 / Negative OECD 476 / Negative OECD 473 / Negative No data
1450-14-2 hexamethyldisilane 5-15% Negative No data No data No data

In addition, 60 structurally similiar chlorosilanes, including the 13 constituents found in MS-Silane, were evaluated using the OECD QSAR Profilers for DNA binding (OECD and OASIS), protein binding (OECD and OASIS), and mutagenicity/carcinogenicity alerts (Benigni/Bossa). These profilers are used to develop groupings based on structural and mechanistic properties of the target chemicals. No protein or DNA binding was identified nor were there any carcinogenicity or mutagenicity alerts.

Based on the available data, the structural similarity of the other constituents of MS-Silane, and the OECD Profiler results, MS-Silane is not expected to be a genetic toxicant.


Short description of key information:
In vitro (read across to MS-Silane constituents [dichloro(dimethyl)silane, CAS 75-78-5 (20 -35% in MS-Silane); chlorotrimethylsilane, CAS 75-77-4 (0 - 5% in MS-Silane); and tetrachlorosilane, CAS 10026-04-7 (0 - 15% in MS-Silane)]:
- Gene mutation (Bacterial reverse mutation assay / Ames test): negative with and without activation in all strains tested (equivalent to OECD TG 471)
- Cytogenicity in mammalian cells: negative with and without activation (similar to OECD TG 473)
- Mutagenicity in mammalian cells: negative (similar to OECD 476)

In addition, hexamethyldisilane, CAS 1450-14-2 (5 - 15% in MS-Silane) was also found to be negative with and without activation in all strains tested (equivalent to OECD TG 471).

In vivo (read across to MS-Silane constituents [dichloro(dimethyl)silane, CAS 75-78-5 (20 -35% in MS-Silane) and chlorotrimethylsilane, CAS 75-77-4 (0 - 5% in MS-Silane)]:
- Negative in mouse micronucleus test (US EPA guideline test, similar to OECD 474) and in the mammalian bone marrow chrom ab test (similar to OECD 475).

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

The available information for MS-Silane indicates that when four MS-Silane constituents were tested in vitro they did not induce mutations in bacterial or mammalian cells, nor cause chromosome aberrations in mammalian cells. The conclusion reached from in vitro results is confirmed by the negative result obtained when two MS-Silane constituents were tested in vivo. Therefore it is considered that classification for mutagenicity is not required.