Silane

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

documentation insufficient for assessment

Remarks:

Lack of information on results

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1993

Report date:

1993

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

yes

Remarks:

gas exposure adaptation of Ames assay

Principles of method if other than guideline:

- Principle of test: Use of a gas sampling bag as the gas exposure vessel

GLP compliance:

not specified

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Silane

EC Number:

232-263-4

EC Name:

Silane

Cas Number:

7803-62-5

Molecular formula:

H4Si

IUPAC Name:

silane

Method

Species / strain

Species / strain 1

Species / strain / cell type:

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

Species / strain 2

Species / strain / cell type:

E. coli WP2 uvr A

Metabolic activation:

with and without

Metabolic activation system:

Type and composition of metabolic activation system: S9 and S9 mix
- source of S9 : Phenobarbital and 5,6-benzoflavone induced liver homegenate from male Sprague-Dawley rats (6 weeks old)
- method of preparation of S9 mix : The S9 mix contained 4 mM NADH, 5 mM G-6-P, 8 mM MgCl2, 33 mM KCl, 100 mM sodium phosphate buffer (pH 7.4) and 10 - 40% S9.
- concentration or volume of S9 mix and S9 in the final culture medium: 50 µl per plate
- quality controls of S9 (e.g., enzymatic activity, sterility, metabolic capability): Not specified

Test concentrations with justification for top dose:

The top concentration of silane was limited to 1% due to the explosivity of this substance

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: Not applicable - gas exposure method.

Controls

Untreated negative controls:

not specified

Negative solvent / vehicle controls:

not specified

True negative controls:

not specified

Positive controls:

yes

Remarks:

non standard controls

Details on test system and experimental conditions:

METHOD OF APPLICATION: gas (diluted in helium)
NUMBER OF REPLICATIONS: Not specified

METHOD OF TREATMENT/ EXPOSURE:
- Cell density at seeding (if applicable): Not specified
- Silane concentrations were not measured by GC as the substance is self-combustible (pyrophoric). Gas sampling bags (10- and 20 L Tedlar bags) and vinyl tubing (Tigon tube).
- Preparation of bacterial plates by the agar over-lay method: 0.5 ml of a 0.1 M phosphate buffer solution (under the direct method) or 0.5 ml of S9 mix (under the metabolic activation method) together with 0.1 ml of the pre-culture solution of tester strains were mixed and immediately after adding 2 ml of top agar containing 0.1 µmole L--histidine/D-biotin or L-tryptophan, the mixture was poured into minimal glucose agar plates.
- Exposure method. The bacterial plates were placed separately upside down without their lids in a plate holder according to their concentralion level and the method used (metabolic activation or the direct method). The plate holder was placed in a 10-l gas sampling bag through an opening on one side and saled with adhesive tape. The air in the bag was removed using a pump to check the bag was air-tight. A flow meter and a pump were connected to the gas dilution bag, and about I liter of the test substance gas dilution was pumped into the gas exposure bag., pumped out again and the reamining aire washed out. After washing out the air, the gas exposure bag was filled with the test substance gas at an adjusted concentration level at a fixed amount per plate The bacterial plates in the gas exposure bag filled with the test substance gas were kept at 25 ºC for 2 hours. After exposure, the test substance gas in the exposure bag was removed. Then sterile air was pumped into the gas exposure bag through a HEPA filter in order to completely replace the test substance with air. The plate holder was removed from the bag and the plates were left to stand in a safety cabinet for 30 minutes and then the lids were replaced.
Incubation - The plates with lids were turned upside down, transferred to a container or vinyl bag and incubated for a further 48 hours. After incubation, revertant colonies were counted.

Rationale for test conditions:

Development of method for mutagenicity testing of gaseous compounds using a gas sampling bag

Results and discussion

Test results

Test results 1

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

not specified

Untreated negative controls validity:

not specified

Positive controls validity:

not specified

Test results 2

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

not specified

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

not specified

Untreated negative controls validity:

not specified

Positive controls validity:

not specified

Test results 3

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

not specified

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

not specified

Untreated negative controls validity:

not specified

Positive controls validity:

not specified

Test results 4

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

not specified

Untreated negative controls validity:

not specified

Positive controls validity:

not specified

Test results 5

Species / strain:

E. coli WP2 uvr A

Metabolic activation:

with and without

Genotoxicity:

not specified

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

not specified

Untreated negative controls validity:

not specified

Positive controls validity:

not specified

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS
- None specified

RANGE-FINDING/SCREENING STUDIES (if applicable): Not specified

STUDY RESULTS
- Concurrent vehicle negative and positive control data . not specified

For all test methods and criteria for data analysis and interpretation:
- Concentration-response relationship where possible : See Fig 1 (attached to EPSR)
- Statistical analysis; not specified
- Any other criteria: not specified

Ames test:
- Signs of toxicity : Not specified
- Individual plate counts : Not provided
- Mean number of revertant colonies per plate and standard deviation : Not reported

HISTORICAL CONTROL DATA (with ranges, means and standard deviation, and 95% control limits for the distribution as well as the number of data)
- Positive historical control data: Not specified
- Negative (solvent/vehicle) historical control data: Not specified

Remarks on result:

not determinable because of methodological limitations

Remarks:

The publication was limited in its presentation of results. There was no information on signs of toxicity, individual plate counts, the mean number of revertant colonies per plate and standard deviation. Dose response curves were presented but in a way that made interpretation difficult and there were no statistical analyses. There were also no concurrent or historical negative and positive control data. The purpose of the publication was to develop a methodological adaption to the Ames test for gaseous substances, some of which were highly flammable or pyrophoric.

Applicant's summary and conclusion

Conclusions:

Under the conditions of this study (not conducted to GLP, reliability score 4), silane was reported to show an increase in revertants in the Salmonella typhimurium strains TA 98 and TA 1537 at a concentration of 1% in the presence or absence of metabolic activation. However, the use of negative and positive controls were not specified and the results were lacking in detail and do not meet the requirements of OECD Test Guideline 471.