Triethoxyoctylsilane

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Gene mutation (Bacterial reverse mutation assay / Ames test): negative with and without metabolic activation in Salmonella typhimurium strains TA98, TA100, TA1535 and TA1537 Escherichia coli WP2 uvrA (draft OECD TG 471) (MA Bioservices, 1998).

Cytogenicity in mammalian cells: negative with and without metabolic activation in Chinese hamster ovary cells (OECD TG 473) (MA Bioservices 1997).

Mutagenicity in mammalian cells: negative in mouse lymphoma L5178Y cells (OECD TG 476) (BSL Bioservice, 2012).

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:

1997.11.14-1997.12.09

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: OECD draft guidelines 471 and 472 (1995)

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Species / strain / cell type:

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

Species / strain / cell type:

E. coli WP2 uvr A

Metabolic activation:

with and without

Metabolic activation system:

Aroclor 1254 induced rat liver S9

Test concentrations with justification for top dose:

75, 200, 600, 1800 and 5000 µg/plate

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: ethanol
- Justification for choice of solvent/vehicle: based on sponsor's request and compatibility with the target cells

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 2-aminoanthracene 1.0 µg/plate

Remarks:

TA98, TA100, TA1535, TA1537, WP2 uvrA with metabolic activation

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

2-nitrofluorene

Remarks:

TA98 without metabolic activation 1.0 µg/plate

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

sodium azide

Remarks:

TA100 and TA1535 without metabolic activation 1.0 µg/plate

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

9-aminoacridine

Remarks:

TA1537 without metabolic activation 75 µg/plate

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

methylmethanesulfonate

Remarks:

WP2 uvrA without metabolic activation 1000 µg/plate

Details on test system and experimental conditions:

METHOD OF APPLICATION: preincubation

ACTIVATION: S9 mix contained glucose-6-phosphate and NADP as co-factors. 0.5 ml of S9 mix containing 10% S9 was added to agar, bacterial suspension and test substance to a total volume of 2.65, giving a final concentration of approximately 1% S9.

DURATION
- Preincubation period: 60 minutes
- Exposure duration: 48 - 72 hours

NUMBER OF REPLICATIONS: triplicate plates, experiment repeated



DETERMINATION OF CYTOTOXICITY
- Method: condition of background lawn

Evaluation criteria:

A result is positive if it causes a dose related increase in the mean revertants per plate of at least one tester strain with a minimum of two increasing concentrations of test article. This would be an increase of at least 3-fold of the solvent control for TA1535 and TA1537 and a 2-fold increase of the solvent control for TA98, TA100 and WP2 uvrA

Statistics:

None available

Key result

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity nor precipitates, but tested up to recommended limit concentrations

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 nor precipitates, but tested up to recommended limit concentrations

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 nor precipitates, but tested up to recommended limit concentrations

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 nor precipitates, but tested up to recommended limit concentrations

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Key result

Species / strain:

E. coli WP2 uvr A

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity nor precipitates, but tested up to recommended limit concentrations

Vehicle controls validity:

valid

Untreated negative controls validity:

not valid

Positive controls validity:

valid

Table 1 Experiment 1 Revertants per plate - preincubation (mean of 3 plates)

Treatment µg/plate	TA98	TA 98	TA100	TA 100	TA1535	TA 1535	TA1537	TA 1537	WP2 uvrA	WP2 uvrA
	-S9	+S9	-S9	= S9	-S9	+S9	-S9	+S9	-S9	+ S9
Solvent control	19	37	138	151	8	9	6	5	16	17
75	20	30	139	148	11	14	6	7	21	24
200	23	38	123	165	10	13	6	5	18	18
600	21	37	111	160	10	12	7	8	17	18
1800	25	31	132	143	9	10	4	6	18	17
5000	20	26	125	133	11	12	5	6	13	14
Positive control	1037	916	605	790	551	112	775	87	437	511

 

Table 2 Experiment 2 Revertants per plate - preincubation (mean of 3 plates)

Treatment µg/plate	TA98	TA 98	TA100	TA 100	TA1535	TA 1535	TA1537	TA 1537	WP2 uvrA	WP2 uvrA
	-S9	+S9	-S9	+ S9	-S9	+S9	-S9	+S9	-S9	+ S9
Solvent Control	14	25	119	129	8	13	8	8	18	22
75	15	23	117	134	5	12	6	5	18	22
200	12	18	111	109	7	9	4	6	14	17
600	10	23	112	123	9	9	5	9	12	14
1800	12	23	90	119	7	8	6	8	15	14
5000	12	24	94	119	9	9	3	6	14	10
Positive control	736	975	500	921	457	94	719	87	438	358

Conclusions:

Triethoxy(octyl)silane has been tested for mutagenicity to bacteria in a study conducted according to OECD draft guidelines 471 and in compliance with GLP. No evidence of a substance related increase in the number of revertants was observed with or without activation in Salmonella typhimurium strains TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2 uvr A in the initial or the repeat experiment, both of which used the preincubation method. Appropriate solvent and positive controls were included and gave expected results. It is concluded that the test substance is negative for mutagenicity to bacteria under the conditions of the test.

Reference 2

Endpoint:

in vitro cytogenicity / chromosome aberration study in mammalian cells

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1994.11.07 - 1997.12.24

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)

Deviations:

no

GLP compliance:

yes

Type of assay:

in vitro mammalian chromosome aberration test

Species / strain / cell type:

Chinese hamster Ovary (CHO)

Details on mammalian cell type (if applicable):

- Type and identity of media: McCoy's 5A medium supplemented with 10% FBS; 2mM L-glutamine; 100 units/ml penicillin and 100 µg/ml streptomycin
- Properly maintained: yes

Metabolic activation:

with and without

Metabolic activation system:

Aroclor 1254 induced rat liver S-9

Test concentrations with justification for top dose:

0.016 - 157 µg/ml

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: ethanol
- Justification for choice of solvent/vehicle: no information provided

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

Remarks:

Ethanol

True negative controls:

no

Positive controls:

yes

Positive control substance:

benzo(a)pyrene

Remarks:

used with S9 metabolic activation 30 µg/ml

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

Remarks:

Ethanol

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: N-methyl-N-nitro-N-nitrosoguanidine (MNNG) dosed at 2 µg/ml

Remarks:

used without S9 activation

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium

DURATION
- Exposure duration: 6 hours with and without S9 metabolic activation or up to 24 and 48 hours without S9
- Expression time (cells in growth medium): 18 hours


SPINDLE INHIBITOR (cytogenetic assays): Colcemid
STAIN (for cytogenetic assays): 5% Giemsa

NUMBER OF REPLICATIONS: 2

NUMBER OF CELLS EVALUATED: 200 per dose level

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

Statistics:

Fisher's exact test and the Cochran-Armitage test

Key result

Species / strain:

Chinese hamster Ovary (CHO)

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

at 20 µg/ml (-MA); 50 µg/ml (+MA)

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

COMPARISON WITH HISTORICAL CONTROL

Chromosome aberration assay

Treatment µg/ml	S9 activation	Treatment /Harvest Time	Mitotic index	Metaphase cells scored for aberrations	Cells with aberrations	Cells with aberrations
					Numberical	Structural
Negative control	-	24	7.2	200	2.5	0.5
Solvent control	-	6/24	6.1	200	2.5	0.5
A-137
8.5	-	6/24	6.8	200	1.0	1.0
11.3	-	6/24	8.2	200	2.0	0.5
15	-	6/24	8.5	200	0.5	2.0
20	-	6/24	3.9	155	0.6	0.0
Positive control	-	6/24	5.2	200	1.5	27.0**
Negative control	+	24	10.9	200	3.0	0.5
Solvent control	+	6/24	8.2	200	5.0	0.5
A-137
21.3	+	6/24	9.5	200	5.0	0.5
28.3	+	6/24	9.4	200	5.0	0.0
37.6	+	6/24	6.6	200	8.0	1.5
50	+	6/24	3.2	200	3.5	1.0
Positive control	+	6/24	3.0	200	8.5	43.0**
Negative control	-	24	12.1	200	0.5	0.5
Solvent control	-	24/24	9.1	200	0.0	1.0
A-137
8.5	-	24/24	7.6	200	0.0	1.0
11.3	-	24/24	11.6	200	1.0	1.0
15	-	24/24	11.7	200	1.5	1.0
20	-	24/24	1.7	37	0.0	0.0
Positive control	-	24/24	5.9	200	1.5	20.5**
Negative control	-	48	5.0	200	0.0	0.5
Solvent control	-	48/48	4.0	200	0.0	1.5
A-137
8.5	-	48/48	4.1	200	0.0	2.0
11.3	-	48/48	3.1	200	0.0	0.0
15	-	48/48	2.0	200	1.0	0.0
20	-	48/48	2.0	200	0.5	2.0
Positive control	-	48/48	2.2	200	1.0	18.0**

** Aberration frequency statistically significant

Conclusions:

Triethoxy(octyl)silane has been tested in a reliable in vitro cytogenetic assay according to OECD TG 473 and in compliance with GLP. The test substance did not induce statistically and biologically significant increases in the chromosomal aberration frequency of CHO (Chinese hamster ovary) cells. It is concluded that the test substance is negative for the induction of chromosome aberrations (not clastogenic) in vitro under the conditions of the test.

Reference 3

Endpoint:

in vitro gene mutation study in mammalian cells

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2011-12-21 to 2012-03-20

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 476 (In Vitro Mammalian Cell Gene Mutation Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.17 (Mutagenicity - In Vitro Mammalian Cell Gene Mutation Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.5300 - In vitro Mammalian Cell Gene Mutation Test

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: IWGT Recommendations

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

(Bayerisches Landesamt für Gesundheit und Lebensmittelsicherheit, Germany)

Type of assay:

mammalian cell gene mutation assay

Target gene:

Thymidine kinase

Species / strain / cell type:

mouse lymphoma L5178Y cells

Details on mammalian cell type (if applicable):

- Type and identity of media: RPMI
- Properly maintained: Yes
- Periodically checked for Mycoplasma contamination: yes
- Periodically "cleansed" against high spontaneous background: yes

Metabolic activation:

with and without

Metabolic activation system:

Liver S9 of Wistar Phenobarbital and ß-Naphthoflavone-induced rat liver S9 mix

Test concentrations with justification for top dose:

Pre-expt I: 0.2, 0.5, 2.5, 5.0, 7.5 and 10.0 mM (+/-MA); Pre-expt II: 0.01, 0.1, 1.0, 2.0, 5.0, 10.0 mM (-MA, 24 h exp); Expt I: 0.1, 0.2, 0.5, 1.0, 2.5, 5.0, 7.5 and 10.0 mM (+/-MA); Expt II: 0.15, 0.3, 0.7, 2.0, 4.0, 6.0, 8.0 and 10.0 mM (+MA); 0.001, 0.002, 0.005, 0.01, 0.02, 0.05, 0.10 and 0.20 mM (-MA)

Vehicle / solvent:

THF was used as solvent (0.35% THF v/v in the samples). To reach a final concentration of 0.35% THF v/v in the samples the test item stock solution was diluted in RPMI + 5% HS for short-term exposure or RPMI + 7.5% HS for long-term exposure. After adding the THF stock solution to cell culture medium precipitate formed.
The solvent was compatible with the survival of the cells and the activity of the S9 mix.

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

Remarks:

THF

True negative controls:

no

Positive controls:

yes

Positive control substance:

benzo(a)pyrene

Remarks:

with metabolic activation 3.5 µg/mL

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

ethylmethanesulphonate

Remarks:

without metabolic activation 200 µg/mL and 300 µg/mL

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

methylmethanesulfonate

Remarks:

without metabolic activation 10 µg/mL

Details on test system and experimental conditions:

METHOD OF APPLICATION: dissolved in THF (0.35% THF v/v in the samples)
DURATION: 4 h (short-term exposure), 24 h (long-term exposure)
Expression time (cells in growth medium): 48 h
Selection time (if incubation with selection agent): about 14 days

SELECTION AGENT ( mutation assay) 5 µg/ml trifluorothymidine
NUMBER OF REPLICATIONS: two separate experiments (I+II) with single exposure; cells were seeded in 4 plates and evaluated
NUMBER OF CELLS SEEDED: 2000 cells per well
DETERMINATION OF CYTOTOXICITY: relative total growth (RTG)

ACTIVATION: S9 mix contained glucose-6-phosphate and NADP as co-factors, and sufficient S9 to give a final protein concentration in the cultures of 0.75 mg/ml

Evaluation criteria:

The test item is considered mutagenic if following criteria are met:
- The induced mutant frequency meets or exceeds the Global Evaluation factor (GEF) of 126 per 10^6 cells
- A dose-dependent increase in mutant frequency is detected.

Besides, combined with a positive effect in the mutant frequency, an increased occurrence of small colonies (≥40% of total colonies) is an indication for potential clastogenic effects and/or chromosomal aberrations.
According to the OECD test guidelines, the biological relevance is considered first for the interpretation of results. Statistical methods might be used as an aid in evaluation the test result.
A test item is considered to be negative if the induced mutant frequency is below the GEF and the trend test is negative.

Statistics:

The non-parametric Mann-Whitney test is applied to the mutation data to prove the dose groups for any significant difference in mutant frequency compared to the negative /solvent controls.

Key result

Species / strain:

mouse lymphoma L5178Y cells

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

RTG of 14.6% and 9.7% without metabolic activation.

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Pre-experiment for toxicity with and without metabolic activation

Concentration (mM)	Number of cells 4 h after treatment	Number of cells 4 h after treatment	Number of cells 24 h after treatment	Number of cells 24 h after treatment	Number of cells 48 h after treatment	Number of cells 48 h after treatment	Suspension growth	Suspension growth	Relative suspension growth	Relative suspension growth
	+S9	-S9	+S9	-S9	+S9	-S9	+S9	-S9	+S9	-S9
Negative control	271000	278000	946000	948000	1600000	1570000	15.1	14.9	89.8	103.6
Negative control	307000	356000	1050000	1150000	1510000	1540000	15.9	17.7	94.1	123.3
Solvent control	307000	256000	104000	807000	1560000	1570000	16.2	12.7	100.0	100.0
Solvent control	339000	313000	112000	101000	1560000	1590000	17.5	16.1	-	-
0.2	284000	271000	77000	593000	1540000	1480000	11.9	8.8	70.4	61.1
0.5	307000	252000	876000	377000	1490000	1190000	13.1	4.5	77.5	31.2
2.5	289000	220000	728000	186000	1620000	637000	11.8	1.9	70.0	13.3
5.0	316000	225000	798000	137000	1550000	286000	12.4	0.9	73.4	6.0
7.5 (P)	303000	271000	650000	293000	1590000	850000	10.3	2.6	61.3	17.8
10.0 (P)	305000	244000	728000	183000	1580000	481000	11.5	1.4	68.3	10.0

 

 

 

Summary: Experiment 1 and 2 with metabolic activation

	Treatment (mM)	RTG (%)	MF (mutants/10^6cells)	IMF (mutants/10^6cells)	Precipitate
	Negative control	103.5	125.6	-	-
Exp. 1	Negative control	98.1	-	-	-
	Solvent control	100.0	135.2	-	-
	Solvent control	-	-	-	-
	0.1	72.3	142.3	7.2	-
	0.2	73.5	143.3	8.1	-
	0.5	84.9	97.1	-38.1	-
	1.0	63.7	182.8	47.6	-
	2.5	67.1	144.4	9.2	-
	5.0	87.2	117.6	-17.6	-
	7.5	78.1	154.8	19.6	-
	10.0	74.3	130.3	-4.8	+
	Positive control	38.4	918.4	783.2	-
	Treatment (mM)	RTG (%)	MF (mutants/10^6cells)	IMF (mutants/10^6cells)	Precipitate
	Negative control	98.9	116.5	-	-
	Negative control	111.8	-	-	-
Exp. 2	Solvent control	100.0	116.7	-	-
	Solvent control		-	-	-
	0.15	111.4	105.1	-11.6	-
	0.3	96.2	131.1	14.4	-
	0.7	75.7	128.5	11.8	-
	2.0	42.3	220.5	103.8	-
	4.0	72.7	138.8	22.2	-
	6.0	58.9	170.6	53.9	-
	8.0	74.1	134.6	17.9	-
	10.0	76.4	154.9	38.2	+
	Positive control	50.5	1141.0	1024.3	-

 

MF = Mutant Frequency

IMF = induced mutant frequency

RTG = relative total growth

 

Summary: Experiment 1 and 2 without metabolic activation

 

	Treatment (mM)	RTG (%)	MF (mutants/10^6cells)	IMF (mutants/10^6cells)	Precipitate
	Negative control	122.0	142.0	-	-
Exp. 1	Negative control	129.6	-	-	-
	Solvent control	100.0	144.3	-	-
	Solvent control	-	-	-	-
	0.1	100.3	177.2	32.9	-
	0.2	87.3	157.4	13.0	-
	0.5	98.4	186.0	41.6	-
	1.0	49.2	190.1	45.7	-
	2.5	37.8*	179.4	35.1	-
	5.0	37.2	179.3	35.0	-
	7.5	17.1	224.1	79.8	+
	10.0	14.6	264.7	120.4	+
	Positive control	75.1	817.6	673.2	-
	Positive control 2	85.2	564.1	419.7	-
	Treatment (mM)	RTG (%)	MF (mutants/10^6cells)	IMF (mutants/10^6cells)	Precipitate
	Negative control	145.4	110.6	-	-
	Negative control	122.8	-	-	-
Exp. 2	Solvent control	100.0	109.3	-	-
	Solvent control	-	-	-	-
	0.001	114.6	108.6	-0.8	-
	0.002	99.3	94.7	-14.6	-
	0.005	103.4	120.0	10.6	-
	0.01	62.1	121.8	12.5	-
	0.02	82.5	160.0	50.6	-
	0.05	98.6	108.4	-0.9	-
	0.10	16.8	173.0	63.6	-
	0.20	0.9	119.1	9.7	-
	Positive control 1	21.3	2373.6	2264.2	-
	Positive control 2	14.7	1826.6	1717.3	-

 

Conclusions:

Triethoxy(octyl)silane has been tested for mutagenicity to mammalian cells in a reliable study conducted according to OECD TG 476 and in compliance with GLP. No biologically relevant increase in mutation rate was found in mouse lymphoma L5178Y cells with or without metabolic activation in either the initial or the repeat experiment, up to limit and cytotoxic concentrations. The global evaluation factor was not exceeded at any concentration. In addition, colony sizing showed no clastogenic effects in either experiment. Appropriate solvent and positive controls were included and gave expected results. It is concluded that the test substance is negative for mutagenicity to mammalian cells under the conditions of the test.

Executive summary:

The test item triethoxy(octyl)silane was assessed for its potential to induce mutations at the mouse lymphoma thymidine kinase locus using the cell line L5178Y.

The selection of the concentrations used in the main experiments was based on data from the pre-experiments. In Experiment I 10.0 mM (with and without metabolic activation) was selected as the highest concentration. In Experiment II 10.0 mM (with metabolic activation) and 0.20 mM (without metabolic activation) were selected as the highest concentrations. Experiment I with and without metabolic activation and Experiment II with metabolic activation were performed as a 4 h short-term exposure assay. Experiment II without metabolic activation was performed as a 24 h long-term exposure assay.

THF was used as solvent (0.35% THF v/v in the samples). After adding the THF stock solution to cell culture medium precipitate formed.

The test item was investigated at the following concentrations:

Experiment I

with and without metabolic activation:

0.1, 0.2, 0.5, 1.0, 2.5, 5.0, 7.5 and 10.0 mM

Experiment II

with metabolic activation:

0.15, 0.3, 0.7, 2.0, 4.0, 6.0, 8.0 and 10.0 mM

and without metabolic activation:

0.001, 0.002, 0.005, 0.01, 0.02, 0.05, 0.10 and 0.20 mM

Precipitation of the test item was noted in Pre-experiment Iwith and without metabolic activation, Pre-experiment II without metabolic activation, Experiment I with and without metabolic activation and in Experiment II with metabolic activation.

In Experiment I with metabolic activation the relative total growth (RTG) was 74.3% for the highest concentration (10.0 mM) evaluated. At two concentrations (1.0 mM and 2.5 mM) growth inhibition was observed with a RTG of 63.7% and 67.1%, respectively. However, considering all evaluated concentrations this effect showed no concentration relationship. The highest concentration evaluated without metabolic activation was 10.0 mM with a RTG of 14.6%. The Experiment without metabolic activation displayed a concentration related decrease in RTG starting at 1.0 mM with a RTG of 49.2%.

In Experiment II with metabolic activation the relative total growth (RTG) was 76.4% for the highest concentration (10.0 mM) evaluated. At two concentrations (2.0 mM and 6.0 mM) growth inhibition was observed with a RTG of 42.3% and 58.9%, respectively. However, considering all evaluated concentrations this effect showed no concentration relationship. The highest concentration evaluated without metabolic activation was 0.20 mM with a RTG of 0.9%. Due to high cytotoxicity the highest concentration was not considered for evaluation of mutagenicity. Experiment II without metabolic activation displayed a concentration related decrease in RTG starting at 0.1 mM with a RTG of 16.8%.

In Experiments I and II no biologically relevant increase of mutants were found after treatment with the test item (with and without metabolic activation).The Global Evaluation Factor (GEF; defined as the mean of the negative/vehicle mutant frequency plus one standard deviation; data gathered from ten laboratories) was not exceeded by the induced mutant frequency at any concentration.

No dose-response relationship was observed in Experiment I with metabolic activation and in Experiment II with and without metabolic activation. In Experiment I without metabolic activation a dose-response relationship was observed in the higher concentrations.

Additionally, in Experiments I and II colony sizing showed no clastogenic effects induced by the test item under the experimental conditions (with and without metabolic activation).

EMS, MMS and B[a]P were used as positive controls and showed distinct and biologically relevant effects in mutation frequency. Additionally, MMS and B[a]P significantly increased the number of small colonies, thus proving the efficiency of the test system to indicate potential clastogenic effects.

This study is classified as acceptable. This study satisfies the requirements for Test Guidelines OPPTS 870.5300, OECD 476 for in vitro mutagenicity (mammalian forward mutation) data.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Genetic toxicity in vivo

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Data are available from reliable in vitro studies on mutagenicity to bacterial and mammalian cells, and cytogenicity to mammalian cells. Where there was more than one result for an endpoint, the most reliable study was chosen as key study.

Triethoxy(octyl)silane has been tested for mutagenicity to bacteria in a study conducted according to OECD draft Guideline 471 and in compliance with GLP (MA Bioservices, 1998). No evidence of a substance related increase in the number of revertants was observed with or without activation in TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2 uvrA in the initial or the repeat experiment, both of which used the preincubation method. No toxicity to bacteria was observed up to limit concentrations. Appropriate solvent and positive controls were included and gave expected results. It is concluded that the test substance is negative for mutagenicity to bacteria under the conditions of the test. The result obtained in this study is supported by two older studies; one of these tested Salmonella typhimurium strains TA 98, TA 100, TA 1535, TA 1537 and TA 1538 (BRRC, 1991) with and without metabolic activation, the other tested only strains TA 97, TA 98 and TA 100 (Kenelly, 1988), with and without metabolic activation. No evidence of test substance induced increase in the number of revertants was observed in either of the supporting studies.

Triethoxy(octyl)silane has been tested in a reliable in vitro cytogenetic assay according to OECD TG 473 and in compliance with GLP (MA Bioservices 1997). The test substance did not induce statistically and biologically significant increases in the chromosomal aberration frequency of CHO (Chinese hamster ovary) cells. No cytotoxicity was observed up to limit concentrations. Appropriate solvent and positive controls were included and gave expected results. It is concluded that the test substance is negative for the induction of chromosome aberrations (not clastogenic) in vitro under the conditions of the test.

Triethoxy(octyl)silane has been tested for mutagenicity to mammalian cells in a reliable study conducted according to OECD TG 476 and in compliance with GLP (BSL Bioservice, 2012). No biologically relevant increase in mutation rate was found in mouse lymphoma L5178Y cells with or without metabolic activation in either the initial or the repeat experiment, up to limit and cytotoxic concentrations. The global evaluation factor was not exceeded at any concentration. In addition, colony sizing showed no clastogenic effects in either experiment. Appropriate solvent and positive controls were included and gave expected results. It is concluded that the test substance is negative for mutagenicity to mammalian cells under the conditions of the test.

In vivo testing is not required as no evidence for genetic toxicity was found in the in vitro studies.

Justification for classification or non-classification

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