N-sodiohexamethyldisilazane

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP compliant guideline study, available as unpublished report, no restrictions, fully adequate for assessment

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2009

Report date:

2009

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Test guideline 3

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes (incl. QA statement)

Remarks:

Experimental Toxicology and Ecology BASF SE, 67055 Ludwigshafen, Germany

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

N-sodiohexamethyldisilazane

EC Number:

213-983-8

EC Name:

N-sodiohexamethyldisilazane

Cas Number:

1070-89-9

Molecular formula:

C6H19NSi2.Na

IUPAC Name:

sodiobis(trimethylsilyl)amine

Details on test material:

- Name of test material (as cited in study report): Na-Hexamethyldisilazane
- Physical state: Solid, beige
- Analytical purity: 98.5%
- Stability: The stability of the test item under storage conditions throughout the study period was guaranteed.
- Storage condition of test material: Room temperature (N2 conditions, protected from humidity)

Method

Target gene:

- S. typhimurium: His-locus
- Escherichia coli: Trp-locus

Species / strain

Species / strain / cell type:

other: S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2 uvr A

Metabolic activation:

with and without

Metabolic activation system:

Liver S9 fraction of phenobarbital/β-naphthoflavone - induced rats

Test concentrations with justification for top dose:

- 1st experiment: Standard plate test: 0, 20, 102, 510, 2550, 5100 µg/plate
- 2nd experiment: Preincubation test: 0, 318.8, 637.5, 1275, 2550, 5100 µg/plate
- 3rd experiment: Preincubation test: 0, 4, 20, 100, 500, 1000 µg/plate (TA 1535, TA 1537and TA 98 with and without S9 mix;
TA 100 and E. coli without S9 mix) and 0, 8, 40, 200, 1000, 2000 µg/plate (TA 100 and E. coli with S9 mix)
- 4rd experiment: Preincubation test: 0, 31.3, 62.5, 125, 250, 500, 750, 1000 µg/plate (TA 100 and TA 1537 without S9 mix) and 0, 62.5, 125, 250, 500, 1000, 1500, 2000 µg/plate (TA 100 with S9 mix)

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle: Due to the limited solubility of the test item in 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.

Controls

Controls 1

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 2-aminoanthracene

Remarks:

with metabolic activation

Controls 2

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: N-methyl-N'-nitro-N-nitrosoguanidine

Remarks:

TA 1535, TA 100; without metabolic activation

Controls 3

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 4-nitro-o-phenylenediamine

Remarks:

TA 98; without metabolic activation

Controls 4

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

9-aminoacridine

Remarks:

TA 1537; without metabolic activation

Controls 5

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

4-nitroquinoline-N-oxide

Remarks:

E. coli WP2 uvrA; without metabolic activation

Details on test system and experimental conditions:

-> 1st EXPERIMENT:
METHOD OF APPLICATION: in agar (plate incorporation)
DURATION
- Exposure duration: 48-72 hours
NUMBER OF REPLICATIONS:
-Three plates per condition
DETERMINATION OF CYTOTOXICITY
- Method: other: Toxicity detected by a decrease in the number of revertants, clearing or diminution of the background lawn (= reduced his- or trp- background growth), or reduction in the titer

-> 2nd, 3rd and 4rd EXPERIMENT:
METHOD OF APPLICATION: preincubation
DURATION
- Preincubation period: 20 minutes
- Exposure duration: 48-72 hours
NUMBER OF REPLICATIONS:
- Three plates per condition
DETERMINATION OF CYTOTOXICITY
- Method: other: Toxicity detected by a decrease in the number of revertants, clearing or diminution of the background lawn (= reduced his- or trp- background growth), or reduction in the titer

Evaluation criteria:

- The test chemical is considered positive in this assay if the following criteria are met: A dose-related and reproducible increase in the number of revertant colonies, i.e. about doubling of the spontaneous mutation rate in at least one tester strain either without S9 mix or after adding a metabolizing system.
- A test item is generally considered non-mutagenic in this test if the number of revertants for all tester strains were within the historical negative control range under all experimental conditions in at least two experiments carried out independently of each other.

Results and discussion

Test results

Species / strain:

other: S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2 uvr A

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

ADDITIONAL INFORMATION ON CYTOTOXICITY:
- A weak bacteriotoxic effect (reduced his- or trp- background growth, slight decrease in the number of his+ or trp+ revertants, reduction in the titer) was observed in the standard plate test depending on the strain and test conditions from about 2 550 μg/plate onward.
- In the preincubation assay bacteriotoxicity (reduced his- or trp- background growth, decrease in the number of his+ or trp+ revertants, reduction in the titer) was observed depending on the strain and test conditions from about 500 μg/plate onward.

TEST-SPECIFIC CONFOUNDING FACTORS
- Precipitation: No precipitation was found with and without S9 mix.

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information):
negative