Triethylsilane

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:

2002-03-04 to 2002-09-13

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2002

Report date:

2002

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: EC directive 92/69/EEC (Methods for the Determination of Toxicity-Mutagenicity.

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

other: ICH Guideline S2A (Specific Aspects of Regulatory Genotoxicity Tests for Pharmaceuticals)

Deviations:

no

Test guideline 4

Qualifier:

according to guideline

Guideline:

other: ICH Guideline S2B (A Standard Battery for Genotoxicity Testing of Pharmaceuticals)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Triethylsilane

EC Number:

210-535-3

EC Name:

Triethylsilane

Cas Number:

617-86-7

Molecular formula:

C6H16Si

IUPAC Name:

triethylsilane

Test material form:

liquid

Method

Target gene:

histidine operon

Species / strain

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102

Metabolic activation:

with and without

Metabolic activation system:

Aroclor induced rat liver S9

Test concentrations with justification for top dose:

10, 31.6, 100, 316, 1000 µg/plate: all strains, with and without metabolic activation, plate incorporation test and preincubation test
1, 3.16 µg/plate: preincubation test, strain TA1537, with metabolic activation

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: Abs. ethylene glycol dimethylether

- Justification for choice of solvent/vehicle: Solubility properties and relative nontoxicity to bacteria

Controls

Controls 1

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

sodium azide

Remarks:

TA 1535, TA 100 without activation, 10 µg/plate

Controls 2

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

2-nitrofluorene

Remarks:

TA 98 without activation, 10 µg/plate

Controls 3

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

9-aminoacridine

Remarks:

TA 1537 without activation, 100 µg/plate

Controls 4

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

methylmethanesulfonate

Remarks:

TA 102 without activation, 1300 µg/plate

Controls 5

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 2-anthracene amide

Remarks:

TA 98, TA 102, TA 1537 with activation, 2 µg/plate

Controls 6

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

cyclophosphamide

Remarks:

TA 100, TA 1535 with activation, 1500 µg/plate

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation); preincubation

ACTIVATION: Aroclor induced rat liver S9
S9 mix components (per 100 mL):
- 5.0 mL rat liver s9
- 2.0 mL 0.4 M MgCl2 + 1.65 M KCl-salt solution (sterile stock solution)
- 141.0 mg glucose-6-phosphate
- 306.5 mg NADP
- 50.0 mL 0.2 M phosphate buffer, pH 7.4 (sterile stock solution)
- sterile water for injection to 100 mL

DURATION:
-Plate incorporation: 48 hours at 37°C
-Preincubation 60 minutes at 37°C
- Preincubation period: 60minutes
- Exposure duration: 24hours
- Expression time (cells in growth medium): 24hours

NUMBER OF REPLICATIONS: 3 plates per concentration and experiment

SELECTION AGENT: histidine-deficient agar

DETERMINATION OF CYTOTOXICITY
- Method: relative total growth

Evaluation criteria:

A test chemical is considered to be show a positive response if the number of revertants is significantly increased compared with the solvent control to at least 2-fold of the solvent control for TA 98, TA 100 and TA 102 and 3-fold of the solvent control for TA 1535 and TA 1537 in both independent experiments.
Positive results have to be reproducible and the histidine independence of the revertants has to be confirmed by streaking random samples in histidine free agar plates

Statistics:

Mann Whitney U test and Spearman's rank correlation.

Results and discussion

Test results

Key result

Species / strain:

S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

reduction in background lawn was observed at 1000 µg/plate with strain TA 100 in the plate incorporation assay, and from 100 µg/plate in the pre-incubation experiment.

Vehicle controls validity:

valid

Positive controls validity:

valid

Additional information on results:

COMPARISON WITH HISTORICAL CONTROL DATA: Controls were within range of historical data.

Any other information on results incl. tables

Table 2: Dose range-finding study Number of revertants per plate (2 plates)

	TA100
Conc. (µg/plate)	Plate 1	Plate 2	Cytotoxic (yes/no)
solvent control	155	136	no
0.316	151	157	no
1	145	128	no
3.16	144	159	no
10	155	146	no
31.6	127	157	no
100	149	151	no
316	155	182	no
1000	154	144	yes
3160	0	0	yes
5000	0	0	yes

Preincubation: number of revertants per plate (mean of 3 plates)

Conc(µg/plate)	TA 98		TA 100		TA 102		TA 1535		TA 1537
	- MA	+ MA	- MA	+ MA	- MA	+ MA	- MA	+ MA	- MA	+ MA
Solvent control	30.7	42.3	137.0	136.0	285.3	281.0	15.0	16.0	5.3	3.3
1	-	-	-	-	-	-	-	-	-	3.0
3.16	-	-	-	-	-	-	-	-	-	3.0
10	38.7	42.7	119.7	144.3	282.3	263.3	14.7	15.0	5.3	5.0
31.6	32.7	43.0	127.7	121.7	285.7	270.3	13.0	17.7	4.0	2.3
100	35.0*	45.3*	142.7*	135.0*	274.0*	301.7	11.0*	13.3	3.7*	4.3*
316	37.3*	41.7*	138.3*	124.7*	260.3*	261.0*	14.7*	15.0*	4.7*	5.0*
1000	0.0*	0.0*	129.3*	136.0*	255.3*	277.0*	16.3*	16.7*	4.7*	3.7*
Positive control	1270.3	1266.0	1375.7	1379.7	1277.0	1373.3	1384.0	1376.7	844.3	420.3

 *cytotoxic

Plate incorporation:number of revertants per plate (mean of 3 plates)

Conc(µg/plate)	TA 98		TA 100		TA 102		TA 1535		TA 1537
	- MA	+ MA	- MA	+ MA	- MA	+ MA	- MA	+ MA	- MA	+ MA
Solvent control	38.3	45.3	116.7	134.0	289.3	272.3	22.3	17.3	5.3	5.7
10	35.7	43.0	129.7	131.0	303.0	276.0	14.0	21.3	4.3	6.0
31.6	37.7	47.7	129.0	139.3	276.3	269.0	14.3	18.7	3.0	3.3
100	38.7	38.7	132.0	118.3	279.3	290.3	16.7	20.3	4.3	3.7
316	41.3	41.0	121.0	140.3	261.0	271.7	19.3	20.3	2.7	5.0
1000	37.0	45.3	117.3*	126.3*	272.0	284.3	17.3	20.7	4.7	6.3
Positive control	1173.7	1163.3	1186.7	1196.0	1329.7	1300.7	657.7	667.7	623.7	718.3

*cytotoxic

Applicant's summary and conclusion

Conclusions:

Triethylsilane has been tested for mutagenicity to bacteria, in a study which was conducted according to the OECD TG 471 and in compliance with GLP. No evidence of a test-substance related increase in the number of revertants was observed with or without metabolic activation in Salmonella typhimurium strains TA 98, TA 100, TA 102, TA 1535 or TA 1537 in the initial plate incorporation assay or the repeat experiment using the pre-incubation method up to cytotoxic concentrations. Appropriate positive and solvent controls were included and gave the expected results. It is concluded that the test substance is negative for mutagenicity to bacteria under the conditions of the test.