Trimethylsilane

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

In vitro:
Gene mutation (Bacterial reverse mutation assay / Ames test): negative with and without metabolic activation in Salmonella typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2 uvrA / pKM101 (OECD TG 471) (Japan Bioassay Research Center 2001a).

Cytogenicity in mammalian cells: negative with and without metabolic activation in Chinese hamster lung IU cells (OECD TG 473) (Japan Bioassay Research Center 2001b).

Link to relevant study records

Reference

Reference 1

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2001-02-01 to 2001-05-10

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Qualifier:

according to guideline

Guideline:

JAPAN: Guidelines for Screening Mutagenicity Testing Of Chemicals

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

yes

Remarks:

only duplicate plates were used, and 2-aminoacridine was the only positive control with metabolic activation

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Target gene:

histidine operon (S. typhimurium); tryptophan operon (E. coli)

Species / strain / cell type:

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

Additional strain / cell type characteristics:

other: E. coli is strain WP2 uvrA / pKM101

Metabolic activation:

with and without

Metabolic activation system:

phenobarbital and 5,6-benzoflavone induced rat liver S9

Test concentrations with justification for top dose:

0.5, 1, 2, 5, 10, 20, 50%

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: HEPA filtered air
- Justification for choice of solvent/vehicle: none given in study report

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Remarks:

air

True negative controls:

no

Positive controls:

yes

Positive control substance:

sodium azide

Remarks:

TA 1535 without metabolic activation; 0.5 μg/plate

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Remarks:

air

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide

Remarks:

TA 100 (0.01μg/plate), TA 98 (0.1 μg/plate) and E. coli (0.005 μg/plate), without metabolic activation

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Remarks:

air

True negative controls:

no

Positive controls:

yes

Positive control substance:

9-aminoacridine

Remarks:

TA 1537, 80 μg/plate, without metabolic activation

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Remarks:

air

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 2-aminoanthracene

Remarks:

all strains with metabolic activation (0.5 μg/plate TA 98; 1 μg/plate TA 100, 2 μg/plate other strains)

Details on test system and experimental conditions:

METHOD OF APPLICATION: other: the substance was prepared by mixing a volume of the gas with a fixed volume of air in a 10 l gas sampling bag (20-1 TEDLER bag).

DURATION

- Exposure duration: 24 hours with lids off; then removed, test substance allowed to evaporate for 20-30 minutes, covered and inverted and returned to the appropriate gas sampling bag and incubated for a further 24 hours.
- Expression time (cells in growth medium): 48 hours

SELECTION AGENT (mutation assays): histidine or tryptophan deficient agar.

NUMBER OF REPLICATIONS: duplicate plates; initial dose determination test was repeated in an independent main test.

DETERMINATION OF CYTOTOXICITY
- Method: other: condition of background lawn; number and size of revertant colonies

METABOLIC ACTIVATION: phenobarbital and 5,6-benzoflavone induced rat liver S9 was purchased from Kikkoman Co., containing 26.02 mg/ml protein. S9 mix contained 10% S9, and glucose-6-phosphae, NADP and NADPH as co-factors. 0.1 ml culture and 0.5 ml S9 were added to 2.0 ml of top agar, giving a final concentration of approximately 2% S9.

Evaluation criteria:

The test substance is considered to be mutagenic when a reproducible dose-related increase in the number of revertant colonies is observed and the number of revertant colonies per plate is more than twice that of the solvent control.

Statistics:

None

Key result

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Key result

Species / strain:

E. coli WP2

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS

- Precipitation: no precipitate was observed


COMPARISON WITH HISTORICAL CONTROL DATA: results were within the range of the historical controls

Table 1 Pre-incubation. Revertants per plate (mean of 2 plates)

Concentration (%)	TA 100		TA 1535		WP2 uvrA		TA 98		TA 1537
	- MA	+ MA	- MA	+ MA	- MA	+ MA	- MA	+ MA	- MA	+ MA
0*	105	114	14	13	77	90	21	28	8	10
0.05	99	103	12	15	75	100	20	23	8	10
0.1	98	116	13	9	66	103	14	20	11	9
0.5	101	96	17	11	64	101	14	26	3	8
1.0	101	105	15	11	69	93	14	27	5	10
5.0	104	118	15	12	79	97	14	23	7	6
10	109	102	14	10	64	91	16	22	6	10
50	98	87	15	15	64	75	12	22	8	5
Positive control	512	1373	355	283	595	1208	556	375	379	261

*Solvent control (air)

Table 2 Pre-incubation. Revertants per plate (mean of 2 plates)

Concentration (%)	TA 100		TA 1535		WP2 uvrA		TA 98		TA 1537
	- MA	+ MA	- MA	+ MA	- MA	+ MA	- MA	+ MA	- MA	+ MA
0*	104	107	11	11	63	91	14	21	8	9
0.5	92	112	8	6	78	89	13	20	5	9
1.0	97	108	10	6	73	92	17	23	5	5
2.0	94	124	11	8	57	78	14	22	10	6
5.0	100	106	6	7	66	99	13	19	4	7
10	108	116	12	9	71	99	18	21	6	7
20	75	103	8	8	61	90	12	22	4	6
50	85	80	6	8	58	79	18	16	6	7
Positive control	492	1147	329	263	857	1209	559	322	321	228

*Solvent control (air)

Conclusions:

Trimethylsilane has been tested in a study conducted according to a national standard (Japanese) method that is similar to OECD 471, and in compliance with GLP. No increase in the number of revertants was observed in the presence or absence of metabolic activation when tested using the gas exposure method at concentrations up to 50%. The observations made in the initial dose-ranging study were reproduced in the main test. The strains tested were Salmonella typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2 uvrA / pKM101, and duplicate plates were used. Appropriate vehicle (air) and positive controls were used and gave expected responses; only 2-aminoanthracene was used as positive control with metabolic activation.

Reference 2

Endpoint:

in vitro cytogenicity / chromosome aberration study in mammalian cells

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2001-01-08 to 2001-02-08

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods

Qualifier:

according to guideline

Guideline:

JAPAN: Guidelines for Screening Mutagenicity Testing Of Chemicals

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)

GLP compliance:

yes

Type of assay:

in vitro mammalian chromosome aberration test

Species / strain / cell type:

mammalian cell line, other: Chinese hamster lung I/U

Metabolic activation:

with and without

Metabolic activation system:

phenobarbital and 5,6-benzoflavone induced rat liver S9

Test concentrations with justification for top dose:

5, 10, 20, 40, 80%

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: HEPA filtered air
- Justification for choice of solvent/vehicle: none given in study report

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Remarks:

air

True negative controls:

no

Positive controls:

yes

Positive control substance:

mitomycin C

Remarks:

without metabolic activation

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Remarks:

air

True negative controls:

no

Positive controls:

yes

Positive control substance:

benzo(a)pyrene

Remarks:

with metabolic activation

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Remarks:

air

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: methylchloride

Remarks:

without metabolic activation

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Remarks:

air

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: vinylchloride

Remarks:

with metabolic activation

Details on test system and experimental conditions:

METHOD OF APPLICATION: other: the test gas or the positive control gas was supplied at fixed concentrations to square glass culture vessels which were then rotated at 1 rpm, so that the cells were directly and repeatedly exposed to a gas and then to a medium solution for a fixed period of time during rotation.

DURATION
- Exposure duration: 6 hours (short treatment with and without metabolic activation) 24 and 48 hours (continuous treatment, without metabolic activation)
- Expression time (cells in growth medium): 18 hours (short treatment)
- Fixation time (start of exposure up to fixation or harvest of cells): 24 or 48 hours

SPINDLE INHIBITOR (cytogenetic assays): Colcemid added 2 hours before chromosome preparations made.
STAIN (for cytogenetic assays): Giesma

NUMBER OF REPLICATIONS: duplicate cultures

NUMBER OF CELLS EVALUATED: 100 cells per culture

DETERMINATION OF CYTOTOXICITY
- Method: mitotic index; cell growth index

OTHER EXAMINATIONS:
- Determination of polyploidy: yes
- Determination of endoreplication: yes


_ METABOLIC ACTIVATION:
phenobarbital and 5,6-benzoflavone induced rat liver S9 was purchased from Kikkoman Co., containing 26.02 mg/ml protein. S9 mix contained 30% S9, and glucose-6-phosphae, NADP and NADPH as co-factors. Final concentration of S9 was 5%.

Evaluation criteria:

Cells were examined for chromatid breaks and exchanges; chromosome breaks and exchanges; fragmentation; gaps; polyploidy; endoreduplication. Substances which caused more than 10% aberrations were considered as positive.

Statistics:

No statistical analysis was performed

Key result

Species / strain:

mammalian cell line, other: CHL/IU

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Summary of results of chromosome aberration study

Preliminary test, 6 hours exposure, without metabolic activation
Concentration (%)	Cells observed	Growth Index	% cells with aberrations	% cells with gaps	% cells with polyploidy
0*	100	100	0	0	0
5	100	87	1	0	0
10	100	102	0	0	0
20	100	101	0	0	0
40	100	89	0	1	1
80	100	92	0	0	0
Positive control	100	-	63	0	0
Preliminary test, 6 hours exposure, with metabolic activation
Concentration (%)	Cells observed	Growth Index	% cells with aberrations	% cells with gaps	% cells with polyploidy
0*	100	100	0	0	0
5	100	97	0	0	1
10	100	104	2	0	1
20	100	104	0	0	0
40	100	94	0	0	0
80	100	86	0	0	0
Positive control	100	-	29	0	3.9
Main test, 6 hours exposure, without metabolic activation
Concentration (%)	Cells observed	Growth Index	% cells with aberrations	% cells with gaps	% cells with polyploidy
0*	200	100	0.5	0	0
20	200	103	1.0	0	0
40	200	102	0	0	0
60	200	93	0	0	0.5
80	200	94	0.2	0	1.5
Positive control	200	-	33	0	0
Main test, 6 hours exposure, with metabolic activation
Concentration (%)	Cells observed	Growth Index	% cells with aberrations	% cells with gaps	% cells with polyploidy
0*	200	100	0	0	0
20	200	92	0	0	0
40	200	93	0.5	0	0
60	200	93	0	0	0.5
80	200	72	0.5	0	0
Positive control	200	-	49	0	0.5
Preliminary test 24 hours exposure, without metabolic activation
Concentration (%)	Cells observed	Growth Index	% cells with aberrations	% cells with gaps	% cells with polyploidy
0*	100	100	0	0	1
5	100	104	2	0	0
10	100	101	0	0	1
20	100	85	0	1	0
40	100	82	0	0	2
80	100	66		0	2
Positive control	100	-	42	1	0
Preliminary test 48 hours exposure, without metabolic activation
Concentration (%)	Cells observed	Growth Index	% cells with aberrations	% cells with gaps	% cells with polyploidy
0*	100	100	0	0	1
5	100	92	0	0	0
10	100	96	0	0	0
20	100	76	0	0	0
40	100	72	0	0	1
80	100	61	0	0	1
Positive control	100	-	41	1	0
Main test 24 hours exposure, without metabolic activation
Concentration (%)	Cells observed	Growth Index	% cells with aberrations	% cells with gaps	% cells with polyploidy
0*	200	100	1	0	0.5
20	200	92	0	0	0
40	200	84	0.5	0	0
60	200	66	0	0	1.0
80	200	60	0	0	1.0
Positive control	200	-	61	3.5	0
Main test 48 hours exposure, without metabolic activation
Concentration (%)	Cells observed	Growth Index	% cells with aberrations	% cells with gaps	% cells with polyploidy
0*	200	0	0.5	100	0
20	200	0	0	97	0
40	200	0	0	98	1.5
60	200	0	0	84	2
80	200	0	0	73	1.5
Positive control	200	5	64.5	-	0

* Solvent control (air)

Conclusions:

Trimethylsilane has been tested according to a national standard method (Japanese) that is equivalent to OECD 473, and in compliance with GLP. No increase in the incidence of chromosome aberrations was observed when tested using a gas exposure method at concentrations up to 80% with and without metabolic activation in Chinese hamster lung cells. Appropriate vehicle and positive controls were used and gave expected results. It is concluded that the test material is negative for the induction of chromosome aberrations under the conditions of the test.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Additional information

Trimethylsilane has been tested in a study conducted according to a national standard (Japanese) method that is similar to OECD 471, and in compliance with GLP (Japan Bioassay Research Center 2001a). No increase in the number of revertants was observed in the presence or absence of metabolic activation when tested using the gas exposure method at concentrations up to 50%. The observations made in the initial dose-ranging study were reproduced in the main test. The strains tested were Salmonella typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2 uvrA / pKM101, and duplicate plates were used. Appropriate vehicle (air) and positive controls were used and gave expected responses; only 2-aminoanthracene was used as positive control with metabolic activation.

Trimethylsilane has been tested according to a national standard method (Japanese) that is equivalent to OECD 473, and in compliance with GLP. No increase in the incidence of chromosome aberrations was observed when tested using a gas exposure method at concentrations up to 80% with and without metabolic activation in Chinese hamster lung cells. Appropriate vehicle and positive controls were used and gave expected results. It is concluded that the test material is negative for the induction of chromosome aberrations under the conditions of the test.

Justification for classification or non-classification

Based on the available in vitro genotoxicity data, trimethylsilane is not classified for mutagenicity according to Regulation (EC) No 1272/2008.