Amino functional alkoxysilanes

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

August 8, 1990 to September 10, 1990

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1990

Report date:

1990

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

1984

Deviations:

not specified

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Test material form:

liquid

Method

Species / strain

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2

Additional strain / cell type characteristics:

other: Genetic identity: RFA mutation using crystal violet; R factor (ampicillin resistance) using ampicillin disc's, UVR B deletion by exposing the strains to ultraviolet light and the histidine requirement by culturing the strains with and without histidines.

Metabolic activation:

with and without

Metabolic activation system:

Mammalian activation mixture (S-9 mix).

Test concentrations with justification for top dose:

Five concentrations of the test material (312.5, 625, 1250, 2500 and 5000 µg/plate), separated by half-log intervals, were evaluated with and without metabolic activation.

Vehicle / solvent:

Dimethylsulfoxide (DMSO)

Controls

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

Positive controls:

yes

Positive control substance:

9-aminoacridine

2-nitrofluorene

sodium azide

other: N-methyl-N-nitro-N-nitrosoguanidine; 2-anthramin

Details on test system and experimental conditions:

Strains details:
TA-1535, TA-98, TA-1537 and TA-100 from Department of Biochemistry, University of California, Berkeley, USA
Escherichia coli WP2 from MRC Cell Mutation Unit, University of Sussex, Falmer. Brighton, England

The genetic identity of each bacterial tester strain is verified at the time that the master plates are made. Genetic identity is verified by testing for the following: RFA mutation using crystal violet; R factor (ampicillin resistance) using ampicillin disc's, UVR B deletion by exposing the strains to ultraviolet light and the histidine requirement by culturing the strains with and without histidines.

The bacterial strains are cultured in Oxoid media #2. The selective medium is Minimal Agar Davis (Difco) with 22 glucose and the overlay agar is 0.6% purified agar with either 0.05 mM histidine for the Salmonella strains or 0.05 mM tryptophan for the E, coli, 0.05 mM biotin and 0.1 M sodium chloride.

Activation System:
Bacteria were exposed to the test substance both in the presence and absence of a mammalian activation mixture (S-9 mix). S-9 mix is prepared in accordance with published procedures (Ames, et al, 1975; Matsushima, et al, 1976), using a 9,000 x g supernatant prepared from Sprague-Dawley adult male rat liver induced by AROCLOR® 1254 five days prior to kill (Organon Teknika Corporation, Durham, NC).

Study System:
Five concentrations of the test material, separated by half-log intervals, were evaluated with and without metabolic activation. Concentration of test chemical (see above) and appropriate tester strain were added to 2 ml top agar held at 45˚C, which was then pour-plated immediately on the surface of hardened minimal agar. In the nonactivation assay, 0.5 ml phosphate buffer was added just prior to plating while 0.5 ml S-9 activation mix was added for the activation assay.

Positive and negative control assays were conducted with each experiment and consisted of direct-acting mutagens for nonactivation assays and mutagens that require metabolic biotransformation in activation assays. Negative controls consisted of the test article solvent in the overlay agar together with the other essential components. Plates were incubated for 72 hours and counted. All testing was done in triplicate.

Evaluation criteria:

The data are presented as the number of revertant colonies per plate. The number of revertant colonies on both negative (solvent) and positive control plates are also presented. The mean (X) number of revertants per plate and standard deviation are also given.

Statistics:

No data.

Results and discussion

Test results

Test results 1

Key result

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not determined

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 2

Key result

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not determined

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 3

Key result

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not determined

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 4

Key result

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not determined

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 5

Key result

Species / strain:

E. coli WP2

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not determined

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

No toxicity or precipitate was noted. There was no evidence of genetic activity observed in any of the tests.

Applicant's summary and conclusion

Conclusions:

Trimethoxy(methyl)silane and its reaction products with [3-(2,3-epoxypropoxy)propyl]trimethoxysilane and 3-(trimethoxysilyl)propylamine has been tested in a valid bacterial reverse mutation assay, conducted according to OECD Test Guideline 471 (1989), and in compliance with GLP, using S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2. No increase in the number of revertants was observed in any test strain, with or without metabolic activation. Appropriate positive and solvent controls were added and gave expected results. It is concluded that the test substance is negative for mutagenicity to bacteria under the conditions of the test.