3-aminopropyltriethoxysilane

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 TA 98, TA 100, TA 1535 and TA 1537 (OECD TG 471) (Hüls AG, 1998a).
Cytogenicity in mammalian cells: negative in V79 CHL cells (OECD TG 473) (Degussa-Hüls AG, 1999).
Mutagenicity in mammalian cells: negative in CHO K-1 cells (OECD TG 476) (Hüls AG, 1998b).

All key studies were conducted according to appropriate OECD guidelines, or protocols similar to appropriate guidelines, and in compliance with GLP.

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:

1998-12-01 to 1998-12-11

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

The restrictions were that only four strains of bacteria were used

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

1983

Deviations:

yes

Remarks:

4 strains used

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Species / strain / cell type:

other: Salmonella typhimurium strains TA 98, TA 100, TA 1535 and TA 1537

Metabolic activation:

with and without

Metabolic activation system:

Phenobarbital and ß-Naphthoflavone induced rat liver S9

Test concentrations with justification for top dose:

0, 50, 160, 500, 1600 and 5000 µg/plate

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO

- Justification for choice of solvent/vehicle: none given in report

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)

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

sodium azide

Remarks:

TA 100, TA 1535 (without activation)

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)

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 2-aminoanthracene

Remarks:

All strains (with activation)

Details on test system and experimental conditions:

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

DURATION

- Preincubation period: 30 minutes

- Exposure duration: 72 hours

- Expression time (cells in growth medium): 72 hours

NUMBER OF REPLICATIONS: 3 plates per test concentration

DETERMINATION OF CYTOTOXICITY

- Method: relative total growth; background lawn assessment

Evaluation criteria:

For a test compound to be considered positive, it must (in two independent experiments) cause at least a doubling in the mean revertants per plate of at least one tester strain. This increase must be accompanied by a dose response towards increasing concentrations of the test article. Single increases in revertant frequencies, which are not dose-related and not reproducible in two independent tests are considered non-relevant. If however these increases do occur in both tests, this will be taken as an indication of mutagenic effect.

Statistics:

Mean number of revertants per plate and the standard deviation around the mean were calculated.

Key result

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

other: >5000 µg/plate

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:

other: >5000 µg/plate

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:

other: >5000 µg/plate

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:

other: >5000 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

COMPARISON WITH HISTORICAL CONTROL DATA: Numbers of spontaneous revertants were within acceptable range

Remarks on result:

other: No mutagenic potential

Table 2a: Experiment 1 Plate incorporation assay Number of revertants per plate (mean of 3 plates)

	TA98			TA100			TA1535
Conc. (µg/plate)	— MA	+ MA	Cytotoxic (yes/no)	— MA	+ MA	Cytotoxic (yes/no)	— MA	+ MA	Cytotoxic (yes/no)
0*	14	30	No	139	151	No	8	9	No
50	16	37	No	147	144	No	8	11	No
160	16	28	No	138	143	No	8	10	No
500	14	29	No	136	150	No	11	9	No
1600	22	41	No	136	150	No	9	13	No
5000	21	27	No	10	171	Yes	10	9	No
Positive Control	104.2	1490	No	536	1592	No	316	153	No

*solvent control with DMSO

Table 2b: Experiment 1 Plate incorporation assay Number of revertants per plate (mean of 3 plates)

	TA1537
Conc. (µg/plate)	— MA	+ MA	Cytotoxic (yes/no)
0*	5	13	No
50	0	11	No
160	2	15	No
500	2	10	No
1600	2	9	No
5000	0	3	Yes
Positive Control	84	109	No

*solvent control with DMSO

Table 3a: Experiment 2 Pre incubation assay Number of revertants per plate (mean of 3 plates)

	TA98			TA100			TA1535
Conc. (µg/plate)	— MA	+ MA	Cytotoxic (yes/no)	— MA	+ MA	Cytotoxic (yes/no)	— MA	+ MA	Cytotoxic (yes/no)
0*	19	25	No	121	116	No	12	9	No
250	21	25	No	97	102	No	7	11	No
500	20	30	No	98	91	No	13	11	No
1000	17	32	No	100	99	No	11	15	No
2000	18	31	No	101	110	No	8	10	No
4000	16	30	No	100	103	No	9	14	No
Positive Control	103	1628	No	608	1384	No	341	216	No

*solvent control with DMSO

Table 3b: Experiment 2 Pre incubation assay Number of revertants per plate (mean of 3 plates)

	TA1537
Conc. (µg/plate)	— MA	+ MA	Cytotoxic (yes/no)
0*	15	16	No
250	17	10	No
500	17	13	No
1000	17	15	No
2000	13	15	No
4000	12	13	No
Positive Control	263	131	No

*solvent control with DMSO

Conclusions:

3-aminopropyl(triethoxy)silane has been tested in a reliable study according to OECD TG 471 and in compliance with GLP using Salmonella typhimurium strains TA 98, TA 100, TA 1535 and TA 1537. The test substance did not show any reproducible mutagenic activity in any of the strains tested up to limit concentrations with and without metabolic activation in either the plate incorporation or the repeat preincubation assay. 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:

1998-10-06 to 1999-01-26

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)

Version / remarks:

1983

Qualifier:

according to guideline

Guideline:

EU Method B.10 (Mutagenicity - In Vitro Mammalian Chromosome Aberration Test)

Version / remarks:

1990

GLP compliance:

yes

Type of assay:

in vitro mammalian chromosome aberration test

Species / strain / cell type:

other: V79 Chinese hamster lung cells

Metabolic activation:

with and without

Metabolic activation system:

Phenobarbital and ß-Naphthoflavone induced rat liver S9

Test concentrations with justification for top dose:

50, 100, 200, 400, 600, 1000, 1800, 3000, 5000 µg/plate

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: medium
- Justification for choice of solvent/vehicle: homogeneous in medium

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

mitomycin C

Remarks:

without activation

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

cyclophosphamide

Remarks:

with activation

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium;

DURATION
- Preincubation period: none
- Exposure duration: 3 hours (experiment 1 and 3); 18 hours (experiment 2)
- Expression time (cells in growth medium): 20 hours
- Fixation time (start of exposure up to fixation or harvest of cells): 20 hours

SPINDLE INHIBITOR (cytogenetic assays): Colcemid
STAIN (for cytogenetic assays): Giesma

NUMBER OF REPLICATIONS: duplicate cultures at each concentration

NUMBER OF CELLS EVALUATED: 2000

DETERMINATION OF CYTOTOXICITY
- Method: mitotic index; cloning efficiency; relative total growth; other:

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

Evaluation criteria:

Criteria for evaluating results (e.g. cell evaluated per dose group): The test chemical is to be considered clastogenic in this assay if 
1. It induces chromosomal aberrations (excl. gaps) in statistically significant manner in one or more concentrations 
2. The induced proportion of aberrant cells at such test substance concentrations exceeds the normal range of the test system  (i.e.>>5%) 
3. Positive results can be verified in an independent experiment

Statistics:

Statistical Methods: Chi-square test

Key result

Species / strain:

Chinese hamster lung fibroblasts (V79)

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

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

Remarks:

>5000 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS
- Effects of pH: pH increased to an unphysiological range so the stock solution was neutralised by addition of HCl
- Other confounding effects: the test substance hydrolyses with water to form (3-aminopropyl)silanetriol. It is the opinion of the reviewer that although hydrolysis is expected to occur within the course of the experiment, this does not invalidate the result as hydrolysis would be expected to occur after ingestion or absorption of the substance.

RANGE-FINDING/SCREENING STUDIES:


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

Remarks on result:

other: No mutagenic potential

Cytotoxicity determination: nine concentrations of the test substance (50-5000 µg/ml) in the presence and absence of metabolic activation were used to determine cytotoxicity and to set doses for the chromosome aberration study. Only after 18 hours exposure without metabolic activation was cytotoxicity observed.

 

The frequency of polyploid cells in both parts of the experiment was within the expected range (<10%) of historical control.

 

Table 1: Results of chromosome analysis Experiment 1 without activation (3-hour exposure, 200 cells scored)

		Solvent Control	Low dose 600 µg/ml	Mid dose 3000 µg/ml	High dose 5000 µg/ml	Positive Control
Proportion of cells with:	exchanges	0	0	0.5	1.0	6.5
	aberrations inc gaps	5.0	5.0	5.0	9.0	26.5
	aberrations excluding gaps	0	0	0.5	1.5	16.0
Mitotic index		7.3	7.8	9.2	8.0	4.9

Table 2: Results of chromosome analysis Experiment 1 with activation (3-hour exposure, 200 cells scored)

		Solvent Control	Low dose 600 µg/ml	Mid dose 3000 µg/ml	High dose 5000 µg/ml	Positive  Control
Proportion of cells with:	exchanges	0.5	0.5	1.0	0	21.0
	aberrations inc gaps	7.0	11.0	8.5	13.0	36.5
	aberrations excluding gaps	0.5	1.5	3.5	1.5	26.0
Mitotic index		5.1	5.2	7.1	7.1	4.0

 Table 3: Results of chromosome analysis Experiment 2 without activation (20-hour exposure, 200 cells scored)

		Solvent Control	Low dose 600 µg/ml	Mid dose 3000 µg/ml	High dose 5000 µg/ml	Positive  Control
Proportion of cells with:	exchanges	0	0.5	0	0.5	17.0
	aberrations inc gaps	6.5	3.5	7.0	5.5	41.5
	aberrations excluding gaps	0.5	0.5	0.5	2.0	34.0
Mitotic index		8.4	8.3	7.2	5.4	3.7

Table 4: Results of chromosome analysis Experiment 2 with activation (3-hour exposure, 200 cells scored)

		Solvent Control	Low dose 600 µg/ml	Mid dose 3000 µg/ml	High dose 5000 µg/ml	Positive  Control
Proportion of cells with:	exchanges	0.5	0.5	1.0	1.0	10.0
	aberrations inc gaps	8.5	7.0	7.5	8.0	32.0
	aberrations excluding gaps	1.0	1.0	2.0	1.0	17.0
Mitotic index		5.3	4.8	5.0	4.3	4.8

Conclusions:

3-aminopropyl(triethoxy)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 V79 Chinese hamster cells in either the initial or the repeat assay. 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:

1998-10-20 to 1998-12-10

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)

Version / remarks:

1997

Deviations:

no

GLP compliance:

yes

Type of assay:

mammalian cell gene mutation assay

Species / strain / cell type:

Chinese hamster Ovary (CHO)

Metabolic activation:

with and without

Metabolic activation system:

Phenobarbital and Beta-Naphthoflavone induced rat liver S9

Test concentrations with justification for top dose:

200, 600, 1800, 3000, 5000 µg/ml

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: culture medium
- Justification for choice of solvent/vehicle: homogeneous (as determined by visual inspection)

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Remarks:

Ham's F12 medium with 2 mM Glutamine, 100 IU/ml Penicillin, and 100 µg/ml Streptomycin

True negative controls:

no

Positive controls:

yes

Positive control substance:

ethylmethanesulphonate

Remarks:

300 µg/ml

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Remarks:

Ham's F12 medium with 2 mM Glutamine, 100 IU/ml Penicillin, and 100 µg/ml Streptomycin

True negative controls:

no

Positive controls:

yes

Positive control substance:

3-methylcholanthrene

Remarks:

10 µg/ml

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium;

DURATION
- Exposure duration: 4 hours (with and without activation)
- Expression time (cells in growth medium): 9 days
- Selection time (if incubation with a selection agent): 9 days
- Fixation time (start of exposure up to fixation or harvest of cells):


SELECTION AGENT (mutation assays): H 10 medium

NUMBER OF REPLICATIONS: triplicate plates, experiment repeated

NUMBER OF CELLS EVALUATED: approximately 5x10 E05

DETERMINATION OF CYTOTOXICITY
- Method: cloning efficiency

Evaluation criteria:

A test compound is considered positive in this assay if it causes a statistically significant, dose related increase in mutant frequency at concentrations of test substance resulting in >20% survival, at a level which is significantly above the maximum spontaneous mutant frequency.

Statistics:

t-test

Key result

Species / strain:

Chinese hamster Ovary (CHO)

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

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

Remarks:

>5000 µg/ml

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Remarks on result:

other: No mutagenic potential

Cytotoxicity test: Concentrations in the range of 50-5000 µg/ml were tested for induction of cytotoxicity. There was no effect of the test substance on cloning efficiency of the CHO cells in the presence or absence of metabolic activation at any concentration tested.

 

The frequency of mutations was low in all groups.  In the absence of metabolic activation mutant frequencies of test substance treated cells were within the range of historical negative controls (i.e., 0-21 mutants per 10 E06 viable cells. The test substance did not produce a significant mutant frequency at any concentration tested in the absence of metabolic activation. In the presence of metabolic activation, the test substance did induce significant increases of the mutant frequencies at the concentration of 600 ug/ml.  The observed mutant frequencies were within the range of the historical negative control (0-23 mutants per 10(6)  viable cells) and did not show a dose response relationship, the  statistical significance is the result of normal assay variation rather  than indicative of a mutagenic effect of the test substance

Table 1 Mutant frequency (x10E-06) (mean of 5 flasks)

Concentration µg/ml	Experiment 1			Experiment 2
	- MA	+ MA	cytotoxicity	- MA	+ MA	cytotoxicity
0 *	3	1	no	4	3	no
200	2	1	no	5	3	no
600	2	5***	no	0	8****	no
1800	0	0	no	0	5	no
3000	1	1	no	5	3	no
5000	0	3	no	1	2	no
Positive control	265**	290**	no	342**	230**	no

* Solvent control with culture medium

** Highly significant, no statistical evaluation

*** Statistically significant, P<0.001 but within the range of the historical negative control

**** Statistically significant 0.1<P<0.05

but within the range of the historical negative control

Conclusions:

In a reliable assay conducted according to OECD TG 476 and in compliance with GLP, the test substance is not mutagenic to mammalian cells regardless of presence or absence of metabolic activation.

Executive summary:

3-aminopropyl(triethoxy)silane has been tested in a reliable assay conducted according to OECD TG 476 and in compliance with GLP. No increase in the mutant frequency was observed in the absence of metabolic activation. In the presence of metabolic activation, a statistically significant increase was observed at a single concentration. As this result was within the range of the mutant frequencies of the historical negative controls, and no dose response relationship was observed, the increases are a result of normal assay variation rather than a mutagenic effect of the test substance. The results from the repeat experiment were consistent with those from the initial test. Expected results were obtained from medium and positive controls. It is the opinion of the reviewer that although the test substance hydrolyses in water, and so the use of aqueous cell culture medium may have led to exposure of the test organisms to the products of hydrolysis rather than the test substance itself, this does not invalidate the test, as hydrolysis would occur in exposed organisms. It is concluded that the test substance in not mutagenic to mammalian cells under the conditions of the test.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Genetic toxicity in vivo

Description of key information

In an intraperitoneal micronucleus assay in mouse, conducted according to a protocol similar to OECD Test Guideline 474 and in compliance with GLP, 3-aminopropyl(triethoxy)silane was observed to be negative for the induction of chromosome aberrations (Bushy Run Research Center, 1988b).

Link to relevant study records

Reference

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1987-12-15 to 1988-01-22

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)

Deviations:

yes

Remarks:

some details not included

GLP compliance:

yes

Type of assay:

micronucleus assay

Species:

mouse

Strain:

Swiss Webster

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS

- Source: Charles Rivers Laboratories

- Age at study initiation: Five weeks

- Assigned to test groups randomly: [yes, by computer generated randomization]

- Housing: Shoe-box type plastic cages (30 x 20 x 12.5 cm)

- Diet (e.g. ad libitum): Agway PROLAB (ad libitum)

- Water (e.g. ad libitum): ad libitum

- Acclimation period: 5 to 6 days prior to dosing


ENVIRONMENTAL CONDITIONS

- Photoperiod (hrs dark / hrs light): 12 hours dark / 12 hours light

Route of administration:

intraperitoneal

Vehicle:

- Vehicle(s)/solvent(s) used: corn oil

- Justification for choice of solvent/vehicle: sponsor indicated the sample reacts with water

Details on exposure:

Intraperitoneal injection

Duration of treatment / exposure:

single dose

Frequency of treatment:

single dose

Post exposure period:

30, 48 and 72 hours

Remarks:

Doses / Concentrations:
90, 56 and 28 mg/kg bw
Basis:
nominal conc.

No. of animals per sex per dose:

5 males and 5 females per dose group

Control animals:

yes, concurrent vehicle

Positive control(s):

triethylenemelamine

- Route of administration: IP injection

- Doses / concentrations: 0.3 mg/kg

Tissues and cell types examined:

Blood

Details of tissue and slide preparation:

CRITERIA FOR DOSE SELECTION: Pre toxicity study (tested to find LD50 using 160, 128 and 102 mg/kg; Doses calculated using this value)

TREATMENT AND SAMPLING TIMES ( in addition to information in specific fields): Blood samples taken 30, 48, and 72 hours after injection

DETAILS OF SLIDE PREPARATION: 2 blood smear slides prepared for each animal per sampling time

METHOD OF ANALYSIS: A minimum of 1000 polychromatic erythrocytes were examined microscopically for each animal per sample time.

Evaluation criteria:

A positive result in the micronucleus test was concluded if at least one statistically significant (p = 0.01) increase above the vehicle control was observed with an indication of a dose-related effect of treatment.

Statistics:

Statistical significance determined using Fisher's Exact Test.

Sex:

male/female

Genotoxicity:

negative

Toxicity:

yes

Remarks:

> 112 mg/kg; no effects in bone marrow

Vehicle controls validity:

valid

Negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

RESULTS OF RANGE-FINDING STUDY
- Dose range in range finding study: 160, 128 and 102 mg/kg;
- Solubility: no information
- Clinical signs of toxicity in test animals: lethality at 160, and 128 mg/kg, no clinical observations made during study
- Rationale for exposure: 25, 50 and 80% LD50 (28, 56 and 90 mg/kg bw)
- Harvest times: 30, 48 and 72 hours

RESULTS OF DEFINITIVE STUDY
- Induction of micronuclei (for Micronucleus assay): negative
- Ratio of PCE/NCE (for Micronucleus assay): not affected by test substance
- Appropriateness of dose levels and route: appropriate dose levels and route
- Statistical evaluation: Analysis of variance

Analysis of variance testing indicated significant sex-related differences in the incidence of micronuclei so data were analysed and reported separately. No statistically significant increases in any treatment group sampled at 30 and 72 hours. Statistically significant increases were observed with female mice sampled at 48 hours, but these were the result of an unusually low value in the vehicle control group compared with historical values, and so were not considered to be of biological significance. The positive control group produced highly significant increases in numbers of micronuclei. The vehicle control values were low and within an acceptable range.

Table 1:Results of in vivo micronucleus test with MALE Swiss-Webster mice (30 hours) 

		Solvent Control	Positive Control	Low dose 28 mg/kg	Mid dose 56 mg/kg	High dose 90 mg/kg
Number of cells evaluated		1000	1000	1000	1000	1000
Sampling time (h)		30	30	30	30	30
Number of erythrocytes	normo­chromatic	-	-	-	-	-
	poly­chromatic	10,000	10,000	10,000	10,000	10,000
	polychromatic with micronuclei	13	159	16	10	9
Ratio of erythro­cytes	polychromatic / normochromatic	22.6	20.2	24	26.6	24.4
	polychromatic with micro­nuclei / normochromatic	2.6	31.8	3.2	2	1.8

Table 2:Results of in vivo micronucleus test with FEMALE Swiss-Webster mice (30 hours) 

		Solvent Control	Positive Control	Low dose 28 mg/kg	Mid dose 56 mg/kg	High dose 90 mg/kg
Number of cells evaluated		1000	1000	1000	1000	1000
Sampling time (h)		30	30	30	30	30
Number of erythro-cytes	normo­chromatic	-	-	-	-	-
	poly­chromatic	10,000	10,000	10,000	10,000	10,000
	polychromatic with micronuclei	5	86	13	9	8
Ratio of erythro­cytes	polychromatic / normochromatic	25.6	26.2	25.8	38.6	25.8
	polychromatic with micro­nuclei / normochromatic	1	17.2	2.6	1.8	1.6

 

Table 3:Results of in vivo micronucleus test with MALE Swiss-Webster mice (48 hours) 

		Solvent Control	Positive Control	Low dose 28 mg/kg	Mid dose 56 mg/kg	High dose 90 mg/kg
Number of cells evaluated		1000	1000	1000	1000	1000
Sampling time (h)		48	48	48	48	48
Number of erythro-cytes	normo­chromatic	-	-	-	-	-
	poly­chromatic	5,000	5,000	5,000	5,000	5,000
	polychromatic with micronuclei	15	Not evaluated	23	13	15
Ratio of erythro­cytes	polychromatic / normochromatic	31.4	Not evaluated	27.2	31	29.4
	polychromatic with micro­nuclei / normochromatic	3	Not evaluated	4.6	2.6	3

Table 4:Results of in vivo micronucleus test with FEMALE Swiss-Webster mice (48 hours) 

		Solvent Control	Positive Control	Low dose 28 mg/kg	Mid dose 56 mg/kg	High dose 90 mg/kg
Number of cells evaluated		1000	1000	1000	1000	1000
Sampling time (h)		48	48	48	48	48
Number of erythro-cytes	normo­chromatic	-	-	-	-	-
	poly­chromatic	5,000	5,000	5,000	5,000	5,000
	polychromatic with micronuclei	3	Not evaluated	10	11	10
Ratio of erythro­cytes	polychromatic / normochromatic	31.2	Not evaluated	24	31.2	21.8
	polychromatic with micro­nuclei / normochromatic	0.6	Not evaluated	2	2.2	2

 

Table 5:Results of in vivo micronucleus test with MALE Swiss-Webster mice (72 hours) 

		Solvent Control	Positive Control	Low dose 28 mg/kg	Mid dose 56 mg/kg	High dose 90 mg/kg
Number of cells evaluated		1000	1000	1000	1000	1000
Sampling time (h)		72	72	72	72	72
Number of erythro-cytes	normo­chromatic	-	-	-	-	-
	poly­chromatic	5,000	5,000	5,000	5,000	5,000
	polychromatic with micronuclei	15	Not evaluated	14	6	12
Ratio of erythro­cytes	polychromatic / normochromatic	26	Not evaluated	33	30.6	27.6
	polychromatic with micro­nuclei / normochromatic	3	Not evaluated	2.8	1.2	2.4

 

Table : Results of in vivo micronucleus test with FEMALE Swiss-Webster mice (72 hours) 

		Solvent Control	Positive Control	Low dose 28 mg/kg	Mid dose 56 mg/kg	High dose 90 mg/kg
Number of cells evaluated		1000	1000	1000	1000	1000
Sampling time (h)		72	72	72	72	72
Number of erythro-cytes	normo­chromatic	-	-	-	-	-
	poly­chromatic	5,000	5,000	5,000	5,000	5,000
	polychromatic with micronuclei	8	Not evaluated	1	3	5
Ratio of erythro­cytes	polychromatic / normochromatic	25.2	Not evaluated	26.6	27.2	26.6
	polychromatic with micro­nuclei / normochromatic	1.6	Not evaluated	0.2	0.6	1

Conclusions:

3-aminopropyl(triethoxy)silane (Silane A-1100 CAS No. 919-30-2) has been tested in a reliable mouse micronucleus assay according to a protocol that is similar to OECD TG 474 and in compliance with GLP. No treatment related increases in numbers of micronuclei in PCEs in Swiss-Webster mice were observed. Relatively high dose levels of CAS No. 919-30-2 were tested up to 80% of the LD50 with no indication of a positive induction of micronuclei. Silane A-1100 CAS No. 919-30-2 was considered to be inactive as a clastogenic agent under the statistical criteria used. It is concluded that the test substance 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

Information is available from reliable studies for all the required in vitro endpoints. When more than one result was available for an endpoint, the most reliable study was selected as a key study. When more than one reliable study was available, the most recent study was selected. The results of all the studies were in agreement.

3-Aminopropyl(triethoxy)silane has been tested in a reliable study conducted according to OECD Test Guideline 471 and in compliance with GLP using Salmonella typhimurium strains TA 98, TA 100, TA 1535 and TA 1537 (Hüls AG, 1998a). The test substance did not show any reproducible mutagenic activity in any of the strains tested up to limit concentrations with and without metabolic activation in either the plate incorporation or the repeat preincubation assay. It is concluded that the test substance is negative for mutagenicity to bacteria under the conditions of the test. The result is supported by a number of assays of lower reliability (Bushy Run Research Center, 1987; Microtest, 1988; Hatano Research Test Institute, 1977; Kakenkyo Test Institute, 1994).

No data are available for mutagenicity to a bacterial strain capable of detecting cross-linking or oxidising mutagens. In view of the lack of genetic toxicity demonstrated in studies on mammalian cells [and in vivo], and the absence of structural features that indicate that such mutagenicity is likely, testing in an appropriate 5th strain is not considered necessary. In addition, many of the organosilicon substances have been tested in an appropriate 5th strain, and the only organosilicon substance which has given a positive result in a bacterial strain capable of detecting cross-linking or oxidising mutagens contains an epoxy-side-chain (which is associated with cross-linking mutagenicity), and this substance was positive in Salmonella typhimurium strains TA 100, TA 1535 as well as in E.coli WP2 uvrA. In addition, data are available for the structurally similar substance, 3-(trimethoxysilyl)propylamine, (CAS 13822-56-5). 3-(Trimethoxysilyl)propylamine was tested up to limit concentrations in Salmonella typhimurium strains TA 98, 100, 1535, 1537 and E.coli WP2 uvrA. No evidence for the induction of mutations was observed with or without metabolic activation in this study which was conducted according to OECD Test Guideline 471 and in compliance with GLP. Both 3-aminopropyl(triethoxy)silane and 3-(trimethoxysilyl)propylamine hydrolyse to propylsilanetriol. The second products of hydrolysis are ethanol and methanol, respectively, which are not considered to be mutagenic (OECD, 2004a; OECD, 2004b).

3-Aminopropyl(triethoxy)silane has been tested in a reliable in vitro cytogenetic assay according to OECD Test Guideline 473 and in compliance with GLP (Degussa-Hüls AG, 1999). The test substance did not induce statistically and biologically significant increases in the chromosomal aberration frequency of V79 Chinese hamster cells in either the initial or the repeat assay. 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. This result is supported by an older study (Shin Etsu, 1994) in which the substance was tested in Chinese hamster lung fibroblasts according to an appropriate Japanese test guideline and in compliance with GLP. No evidence of clastogenicity was observed.

Additional evidence for lack of in vitro effects on chromosomes comes from a sister chromatid exchange assay in which no increase in exchanges was observed (Bushy Run Research Center, 1988a).

3-Aminopropyl(triethoxy)silane has been tested in a reliable assay conducted according to OECD Test Guideline 476 and in compliance with GLP (Hüls AG, 1998b). No increases in the mutant frequency were observed in the absence of activation in Chinese hamster ovary cells. In the presence of activation, a statistically significant increase was observed at a single concentration. As this result was within the range of the mutant frequencies of the historical negative controls, and no dose response relationship was observed, the increases are a result of normal assay variation rather than a mutagenic effect of the test substance. The results from the repeat experiment were consistent with those from the initial test. Expected results were obtained from medium and positive controls. It is the opinion of the reviewer that although the test substance hydrolyses in water, and so the use of aqueous cell culture medium may have led to exposure of the test organisms to the products of hydrolysis rather than the test substance itself, this does not invalidate the test, as hydrolysis would occur in exposed organisms. It is concluded that the test substance is not mutagenic to mammalian cells under the conditions of the test. This result is supported by data from an older study in which 3-aminopropyltriethoxysilane was tested for mutagenicity to Chinese hamster ovary cells (Bushy Run Research Center, 1988a). No evidence for the induction of mutations was observed with and without metabolic activation.

The conclusions from the in vitro assays are confirmed in an in vivo micronucleus assay, in which 3-aminopropyl(triethoxy)silane was tested in according to a protocol that is similar to OECD Test Guideline 474 and in compliance with GLP (Bushy Run Research Center, 1988b). No treatment related increases in numbers of micronuclei in PCEs in Swiss-Webster mice were observed. Relatively high dose levels were tested up to 80% of the LD50 with no indication of a positive induction of micronuclei. Appropriate positive and vehicle controls were included and gave expected responses. The test substance was considered to be inactive as a clastogenic agent under the statistical criteria used. It is concluded that the test substance is negative for the induction of chromosome aberrations under the conditions of the test.

BioServices, 1997. Study G97AS98.504001. Testing laboratory: MA BioServices, Inc. Report no.: G97AS98.504001. Owner company: Momentive. Report date: 1997-10-20.

OECD (2004a): SIDS Initial Assessment Report for SIAM 19, Berlin, Germany, 18-20 October 2004, Methanol, CAS 67-56-1.

OECD (2004b): SIDS Initial Assessment Report for SIAM 19, Berlin, Germany, 19-22 October 2004, Ethanol, CAS 64-17-5.

Justification for classification or non-classification

The available information for the substance indicates that when tested in vitro, 3-aminopropyl(triethoxy)silane (CAS number 919 -30 -2) does not induce mutations in bacterial or mammalian cells, nor chromosome aberrations in mammalian cells. The results from the in vitro testing are substantiated by an in vivo micronucleus study in rat (ip administration), in which no substance-related increase in the number of micronucleated cells was observed. Therefore, 3-aminopropyl(triethoxy)silane does not require classification for mutagenicity according to Regulation (EC) No 1272/2008.