Silicon boride oxide

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Ames test: negative in vitro mammalian chromosome aberration test: negative

Link to relevant study records

Reference

Endpoint:

in vitro gene mutation study in bacteria

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

March 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline and GLP conformant study

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Qualifier:

according to guideline

Guideline:

EU Method B.13/14 (Mutagenicity - Reverse Mutation Test Using Bacteria)

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.5100 - Bacterial Reverse Mutation Test (August 1998)

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Target gene:

Salmonelle typhimurium: histidine
Escherichia coli WP2 uvrA: tryptophan

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98 and TA 100

Species / strain / cell type:

E. coli WP2 uvr A

Metabolic activation:

with and without

Metabolic activation system:

S9 fraction of phenobarbital/b-naphtoflavone-treated rats

Test concentrations with justification for top dose:

Standard plate test and preincubation test: 33, 100, 333, 1000, 2875, and 5750 μg/plate

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle: Due to the limited solubility of the test substance in ultrapure water, DMSO was used as vehicle, which had been demonstrated to be suitable in bacterial reverse mutation tests and for which historical control data are available

Untreated negative controls:

yes

Remarks:

sterility control

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

4-nitroquinoline-N-oxide

9-aminoacridine

other: 2-aminoanthracene (2-AA), N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), 4-nitro-o-phenylenediamine (NOPD)

Species / strain:

S. typhimurium TA 1535, TA 1537, TA 98 and TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

A bacteriotoxic effect was observed in the standard plate test depending on the strain and test conditions from about 2 875 μg/plate onward depending on the bacterial strain.

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Species / strain:

E. coli WP2 uvr A

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

A bacteriotoxic effect was observed in the standard plate test depending on the strain and test conditions from about 2 875 μg/plate onward.

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

Test substance precipitation was found from about 1 000 μg/plate onward with and without S9 mix.
No relevant increase in numbers of his+ or trp+ revertants were observed in either bacterial strain with or without metabolic activation.

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Conclusions:

Interpretation of results (migrated information):
negative

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Additional information

Additional information from genetic toxicity in vitro:

In the Ames test, a relevant increase in the number of his+ or trp+ revertants was not observed in the standard plate test or in the preincubation test either without S9 mix or after the addition of a metabolizing system. The test substance was cytotoxic at doses >2000 ug/ml.

In an in vitro mammalian chromosome aberration test on V79 cells with and without metabolic activation, no biologically relevant increase in the frequencies of polyploid cells was found after treatment with the test item as compared to the controls.

Justification for selection of genetic toxicity endpoint
Guideline and GLP conformant study

Justification for classification or non-classification

Considering the data available, silicon boride oxide does not fulfill the criteria for classification layed out in Regulation EC 1272/2008 (CLP). Therefore, non-classification is warranted.