3-chloropropyltrimethoxysilane

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Gene mutation (Bacterial reverse mutation assay / Ames test): positive with and without activation in strains TA-100 and TA-1535, and in strain TA-98 without activation (OECD Test Guideline 471 and in compliance with GLP) (Dow Corning Corporation, 1993).

Mutagenicity in mammalian cells: positive with metabolic activation L5178Y mouse lymphoma cells (similar to OECD Test Guideline 476 and in compliance with GLP) (Dow Corning Corporation, 1995).

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

no

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Species / strain / cell type:

S. typhimurium, other: TA98, TA100, TA1535, TA1537, TA1538, TA102

Species / strain / cell type:

E. coli WP2 uvr A

Metabolic activation:

with and without

Metabolic activation system:

0.5 ml Aroclor 1254 induced rat liver S9

Test concentrations with justification for top dose:

100, 333, 1000, 3333 and 5000 µg/plate

Vehicle / solvent:

- Vehicle: DMSO at 50 µl

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 2-aminoanthracene

Remarks:

with activation, all strains except TA 102

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other:  sterigmatocystin

Remarks:

TA 102 with activation

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

2-nitrofluorene

Remarks:

TA 98 and TA 1537 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 and TA 1535 without activation

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

cumene hydroperoxide

Remarks:

TA 102 without activation

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

methylmethanesulfonate

Remarks:

E coli without activation

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation)

DURATION
- Exposure duration: 48-72 hours
- Expression time (cells in growth medium): 48-72 hours
- Fixation time (start of exposure up to fixation or harvest of cells): 48-72 hours

NUMBER OF REPLICATIONS: triplicate plates

DETERMINATION OF CYTOTOXICITY
- Method: other: condition of background lawn

Evaluation criteria:

All cultures must demonstrate the characteristic mean number of spontaneous revertants in the vehicle control as shown below:  

TA98          10 - 50
TA100         80 - 240
TA1535         5 - 45
TA1537         3 - 21
TA1538         5 - 35
TA102        200- 380
WP2uvrA     10 - 60

For the test article to be evaluated positive, it must cause 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. Data sets for strains TA1535, TA1537 and TA1538 will be judged positive if the increase in mean revertants at the peak of the dose response is equal to greater than three times the mean vehicle control value. Data sets for strains TA98, TA100, and WP2uvrA will be judged positive if the increase in mean revertants at the peak of the dose-response is equal to or greater than two times the mean vehicle control value.

Statistics:

None

Key result

Species / strain:

S. typhimurium TA 98

Metabolic activation:

without

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Remarks:

none

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium, other: TA100 and TA1535

Metabolic activation:

with and without

Genotoxicity:

positive

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:

bacteria, other: Salmonella typhimurium TA1537, TA1538, TA102; Escherichia coli/WP2uvrA

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:

No precipitate or bacterial toxicity was observed in this assay. 
A positive response was observed with bacterial tester strain TA-98 in the absence of metabolic activation and tester strains TA-100 and TA-1535 with and without metabolic activation. The authors concluded that under these experimental conditions, the test material caused mutagenicity in three bacterial tester strains.
Cytotoxic concentration: 
*   With metabolic activation:  No toxicity observed at the  maximum dose of 5000 ug/plate
*   Without metabolic activation: No toxicity observed at the  maximum dose of 5000 ug/plate
Genotoxic effects (e.g. positive, negative, unconfirmed, dose-response, equivocal): 
*   With metabolic activation: Positive in TA-100 and TA-1535
*   Without metabolic activation: Positive in TA-98, TA-100 and TA-1535

Remarks on result:

other: all strains/cell types tested

Table 1: Dose range-finding study

	TA 100			E.coli WP2 uvrA
Conc. (µl/ml)	- MA	+ MA	Cytotoxic (yes/no)	- MA	+ MA	Cytotoxic (yes/no)
0	122	129	no	13	15	no
6.7	140	163	no	16	23	no
10	121	140	no	11	15	no
33	142	129	no	17	14	no
67	143	118	no	26	18	no
100	144	119	no	20	21	no
333	151	129	no	20	23	no
667	148	158	no	26	10	no
1000	209	196	no	25	18	no
3333	298	275	no	22	20	no
5000	308	446	no	23	27	no

*solvent control with DMSO

 

Table 2: - Plate incorporation:Number of revertants per plate (mean of 3 plates)

	TA 98			TA 100			TA 1535
Conc. (µl/ml)	- MA	+ MA	Cytotoxic (yes/no)	- MA	+ MA	Cytotoxic (yes/no)	- MA	+ MA	Cytotoxic (yes/no)
0*	19	NT	no	115	169	no	9	12	no
100	12	NT	no	137	168	no	18	13	no
333	24	NT	no	148	166	no	21	16	no
1000	30	NT	no	136	206	no	61	41	no
3333	34	NT	no	232	271	no	138	165	no
5000	43	NT	no	246	356	no	190	248	no
Positive control	262	NT	no	494	1023	no	428	176	no

*solvent control with DMSO

NT: not tested

 

Table 3: -Plate incorporation:Number of revertants per plate (mean of 3 plates)

	TA 1537			TA 1538			TA 102			E.coli WP2 uvrA
Conc. (µl/ml)	- MA	+ MA	Cytotoxic (yes/no)	- MA	+ MA	Cytotoxic (yes/no)	- MA	+ MA	Cytotoxic (yes/no)	- MA	+ MA	Cytotoxic (yes/no)
0*	7	7	no	6	23	no	263	359	no	17	21	no
100	6	7	no	4	16	no	30	348	no	18	12	no
333	6	12	no	6	18	no	309	358	no	14	22	no
1000	9	9	no	6	20	no	295	414	no	20	22	no
3333	6	9	no	9	22	no	314	409	no	25	27	no
5000	9	8	no	11	18	no	329	404	no	23	25	no
Positive control	1052	129	no	321	944	no	1300	2312	no	132	570	no

*solvent control with DMSO

Conclusions:

(3-Chloropropyl)trimethoxysilane has been tested for mutagenicity in a valid gene mutation study in bacterial strains S. typhimurium TA-98,TA-100,TA-1535,TA-1537,TA-1538, TA-102 and E. coli WP2 uvr A with and without metabolic activation, conducted according to a protocol similar to OECD Test Guideline 471 and in compliance with GLP. An dose-dependent increase in the number of revertants was observed in S. typhimurium strains TA100 and TA1535 with and without metabolic activation, and in strain TA98 in the absence of metabolic activation. It is concluded that (3-chloropropyl)trimethoxysilane is positive for mutagenicity in bacteria under the conditions of this test.

Reference 2

Endpoint:

in vitro gene mutation study in mammalian cells

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

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

Version / remarks:

appears to be guideline but none mentioned in report

Deviations:

yes

Remarks:

positive controls used are not those recommended for the TK locus

GLP compliance:

yes

Type of assay:

mammalian cell gene mutation assay

Species / strain / cell type:

mouse lymphoma L5178Y cells

Metabolic activation:

with and without

Metabolic activation system:

Aroclor 1254-induced Rat Liver  250 µl S9, cofactor NADP

Test concentrations with justification for top dose:

25, 50, 60, 70, 80 and 90 µg/ml (however 90 µg/ml was too toxic to be evaluated for mutagenicity) in the presence of S9.
500, 1000, 1500, 2000 and 2500 µg/ml in the absence of S9

Selection of dose levels for the mutation assay was based on reduction of suspension growth relative to the solvent control. Substantial toxicity, i.e., suspension growth of less than equal to 50% of the solvent control, was observed at 5000 µg/ml without activation and greater than or equal to 50% at 50 µg/ml with S9 activation. Based on these findings, the dose chosen for the mutagenesis assay ranged from 500 to 5000 µg/ml for the non-activated cultures and 10 to 100 µg/ml for the S9 activated cultures. 

Vehicle / solvent:

Acetone was determined to be the solvent of choice based on solubility of the test article and compatibility with the target cells.  

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Remarks:

0.25 and 0.50 µl/ml 

Positive control substance:

ethylmethanesulphonate

Remarks:

without activation

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

7,12-dimethylbenzanthracene

Remarks:

with activation 0.25 and 0.50 µl/ml 

Details on test system and experimental conditions:

The material was tested in the L5178Y/TK+/- mouse lymphoma mutagenesis assay in the absence and presence of Aroclor-induced rat liver S9. The assay was performed in two phases. The first phase, the preliminary toxicity assay was used to establish the dose range for the mutagenesis assay. The second phase, the mutagenesis assay was used to evaluate the mutagenic potential of the test article. A confirmatory assay which is required by full compliance of OECD and EPA guidelines was not performed. 

Test Design: *  Number of replicates:  2

Evaluation criteria:

In evaluation of the data, increases in the mutant frequencies which occurred only at highly toxic concentrations (i.e. less than 10% total growth) were not considered biologically relevant. All conclusions were based on sound scientific judgment; however, as a guide to interpretation of the data, the test article was considered to induce a positive response if a concentration-related increase in mutant frequency was observed and more than one dose level with 10% or greater total growth exhibited a mutant frequency two-fold greater than the solvent control. A doubling above background at one or more dose levels with 10% or greater total growth with no evidence of a dose-response was considered equivocal. Test articles not producing a doubling above background at one or more dose levels with 10% or greater total growth were concluded to be negative.    

The following criteria must be met for the mutagenesis assay to be considered valid. The mutant frequency of the positive controls must be at least twice that of the appropriate solvent control cultures. The spontaneous mutant frequency of the solvent controls must be between 20 and 100 TFT-resistant mutants per 106 surviving cells. The cloning efficiency of the solvent controls must be greater than 50%.

Key result

Species / strain:

mouse lymphoma L5178Y cells

Metabolic activation:

with

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

With metabolic activation:  80 and 90 µg/ml;   Without metabolic activation:  2000 and 2500 µg/ml

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

In the mutagenesis assay, no non-activated test article-treated cultures and eight S9-activated test article-treated cultures exhibited mutant frequencies that were at least twice that of the solvent control. A dose-response trend was noted in the S9-activated cultures.
Toxicity in the cloned cultures, i.e., total growth of less than or equal to 50% on the solvent control, was observed at a dose of 2000 µg/ml without activation and at doses of greater than or equal to 60 µg/ml with S9 activation.  
The trifluorothymidine-resistant colonies for the cloned S9-activated positive control, solvent control and test article-treated cultures were sized according to diameter over a range from 0.2 to 1.1 mm. The data on colony size distributions showed an increase in the frequency of medium to large colonies when the treated cultures were compared to the solvent control cultures. 
Under the conditions of this study, the test article was considered to be negative without S9 activation and positive with S9 activation in the L5178Y/TK +/- Mouse Lymphoma Mutagenesis Assay.
Cytotoxic concentration: 
*   With metabolic activation:  80 and 90 µg/ml
*   Without metabolic activation:  2000 and 2500 µg/ml
Genotoxic effects (e.g. positive, negative, unconfirmed, dose-response, equivocal): 
*   With metabolic activation:  Positive
*   Without metabolic activation:  Negative

Table 1 Induced mutant frequency, without activation (average of 3 plates scored for each culture)

Concentration µg/ml	Culture	Mutant colonies (av)	Viable count	Mutant frequency	Induced mutant frequency	% total growth
0*	1	15 ± 3	171	18	-	-
	2	18 ± 3	163	22	-	-
500	A	14 ± 2	182	15	-5	104
	B	15 ± 4	193	16	-4	102
1000	A	14 ± 5	168	17	-3	84
	B	24 ± 2	165	29	9	82
1500	A	25 ± 5	174	29	9	71
	B	17 ± 2	169	20	0	56
2000	A	23 ± 8	147	31	11	31
	B	++	++	-	-	-
Positive control	2.5 µg/ml	259 ± 2	113	458	433	-
	5.0 µg/ml	298 ± 3	86	693	668	-

*solvent control with acetone

++ too toxic to clone

Table 2 Induced mutant frequency, with activation (average of 3 plates scored for each culture)

Concentration µg/ml	Culture	Mutant colonies (av)	Viable count	Mutant frequency	Induced mutant frequency	% total growth
0*	1	44 ± 5	145	61	-	-
	2	38 ± 8	113	67	-	-
25	A	66 ± 3	+	+	+	+
	B	84 ± 6	115	146	82	72
50	A	90 ± 3	114	158	94	63
	B	83 ± 2	109	152	88	52
60	A	82 ± 4	98	167	103	46
	B	71 ± 5	96	148	84	37
70	A	69 ± 3	107	129	65	41
	B	60 ± 5	87	138	74	19
80	A	60 ± 5	+	+	+	+
	B	63 ± 11	75	168	104	10
Positive control	2.5 µg/ml	103 ± 8	58	355	286	31
	5.0 µg/ml	52 ± 5	19	547	478	3

90 µg/ml was not evaluated for mutagenicity as too toxic to clone.

* solvent control with acetone

+ Culture lost

Conclusions:

(3-Chloropropyl)trimethoxysilane has been tested for mutagenicity in a reliable mammalian mutagenicity study in L5178Y mouse lymphoma cells with and without metabolic activation, conducted according to a protocol similar to OECD Test Guideline 476 and in compliance with GLP. The test material was considered to be negative for mutagenicity when tested without metabolic activation and positive when tested with metabolic activation. (3-Chloropropyl)trimethoxysilane has been concluded to be positive for mutagenicity in mammalian cells under the conditions to the study.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (positive)

Genetic toxicity in vivo

Description of key information

Micronucleus assay in mouse (ip administration): Negative (similar to OECD Test Guideline 474 and in compliance with GLP) (BRRC, 1993).

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

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)

Deviations:

yes

Remarks:

only 1000 PCE scored for micronuclei

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 River laboratories
- Age at study initiation: 5 weeks
- Weight at study initiation: 22-7 to 25.5 g (males); 17.9 to 21.4 g (females)
- Assigned to test groups randomly: yes, under following basis: nonstratified randomization procedure based on body weight
- Fasting period before study: no
- Housing: group housed in shoe box type plastic cages
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 1 week

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22°C
- Humidity (%): 40-70%
- Air changes (per hr): no information
- Photoperiod (hrs dark / hrs light): 12/12


IN-LIFE DATES: From: 1991-07-08 To: 1991-09-03

Route of administration:

intraperitoneal

Vehicle:

- Vehicle(s)/solvent(s) used: corn oil;
- Justification for choice of solvent/vehicle: none given - standard vehicle

Details on exposure:

(3-Chloropropyl)trimethoxysilane (CAS No. 2530-87-2) was given to both male and female Swiss-Webster mice as a single dose by intraperitoneal injection. Based upon mortality data obtained in a range-finding study, the acute intraperitoneal LD50 for the combined sexes was calculated to be 2031 mg/kg (3-Chloropropyl)trimethoxysilane (95% confidence interval, 1672 to 2456 mg/kg).  The doses for the definitive micronucleus assay were selected by the study director as approximately 25%, 50%, and 90% of the LD50 or 500, 1000, and 1625 mg/kg (3-Chloropropyl)trimethoxysilane.

Frequency of treatment:

Single dose

Post exposure period:

30, 48 and 72 hours

Dose / conc.:

0 other: mg/kg

Remarks:

Nominal concentration. Control, corn oil

Dose / conc.:

500 other: mg/kg

Remarks:

Nominal concentration

Dose / conc.:

1 000 other: mg/kg

Remarks:

Nominal concentration

Dose / conc.:

1 625 other: mg/kg

Remarks:

Nominal concentration

No. of animals per sex per dose:

5 per sex per dose, except high dose where 8/sex/dose were used

Control animals:

yes, concurrent vehicle

Positive control(s):

- triethylenemelamine
- dissolved in ethanol then diluted with sterile distilled water
- Justification for choice of positive control(s): none given, standard control
- Route of administration: ip
- Doses / concentrations:0.3 mg/kg

Tissues and cell types examined:

Peripheral erythrocytes

Details of tissue and slide preparation:

CRITERIA FOR DOSE SELECTION: based on toxicity data

DETAILS OF SLIDE PREPARATION: 1 or 2 blood smear slides prepared per animal, stained with Gurr's R-66 Giesma

METHOD OF ANALYSIS: PEC: PNEC ratio for 1000 cells per animal calculated to estimate toxicity. 100 PCE/animal scored for presence of micronuclei

Statistics:

Mann-Whitney U test, probability value of <0.05 (1-tailed) used as critical level for significance.

Key result

Sex:

male/female

Genotoxicity:

negative

Toxicity:

yes

Remarks:

PCE/NCE ratio decreased at 72 h, high dose

Vehicle controls validity:

valid

Negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

There were no signs of toxicity in male or female mice in the 500 mg/kg group, except that 1 female exhibited ataxia during the first hour post-treatment. All of the males and females in the 1000 mg/kg group exhibited ataxia and 2 of the males also had tremors during the first hour after treatment. In males and females treated at 1625 mg/kg chloropropyltrimethoxysilane, ataxia, tremors, and prostration were observed during the first hour after treatment. Other clinical signs in the high dose females included myoclonic jerks and vocalization. There were no significant clinical observations in male or female mice from the afternoon of Day 1 through the end of the study.  

There was a significant decrease in the polychromatophilic erythrocyte (PCE) to normochromatophilic erythrocyte (NCE) ratios at the 72 hr sampling  time among male mice (50.6% of control) treated with 1625 mg/kg cloropropyltrimethoxysilane. However, there was no evidence that chloropropyltrimethoxysilane was excessively toxic to the bone marrow at the concentrations chosen for the study. No significant increases in the incidences of micronucleated PCE were observed at 500, 1000, or 1625 mg/kg chloropropyltrimethoxysilane at the 30, 48 or 72 hr sampling times in mice of either sex.

RESULTS OF RANGE-FINDING STUDY
- Dose range: information not included in study report
- Rationale for exposure: based on ip LD50

RESULTS OF DEFINITIVE STUDY
- Induction of micronuclei (for Micronucleus assay): negative
- Ratio of PCE/NCE (for Micronucleus assay): decreased
- Appropriateness of dose levels and route: yes
- Statistical evaluation: yes

Table 2 Results of in vivo micronucleus test

Treatment			Solvent control	Low dose	Mid dose	High dose	Positive control
Sampling time			30 h
Number of erythrocytes	normochromatic (NCE)	m	NR	NR	NR	NR	NR
		f	NR	NR	NR	NR	NR
	polychromatic (PCE)	m	5000	5000	5000	5000	5000
		f	5000	5000	5000	5000	5000
	PCE with micronuclei (MPCE)	m	12	13	15	12	061
		f	9	5	4	11	67
Ratio of erythrocytes	PCE/1000 NCE	m	34	35	33	28.4	24.6
		f	28.4	35	29.6	29.0	28.4
	MPCE/NCE (%)	m	0.24	0.26	0.30	0.24	1.22
		f	0.18	0.10	0.08	.22	1.34
Sampling time			48 h
Number of erythrocytes	normochromatic (NCE)		NR	NR	NR	NR	NE
	polychromatic (PCE)	b	10000	10000	10000	10000	NE
Ratio of erythrocytes	PCE with micronuclei (MPCE)		20	24	16	17	NE
	PCE/1000 NCE	m	26.8	24.4	23.4	19.8	NE
		f	24.8	23.2	22.4	23.8	NE
	MPCE/NCE (%)		0.2	0.24	0.16	0.17	NE
		72 h
	polychromatic (PCE)	b	10000	10000	10000	10000	NE
	PCE with micronuclei (MPCE)	b	16	15	16	16	NE
	PCE/NCE (%)	b	0.16	0.15	0.16	0.16	NE
	MPCE/NCE	m	35.2	30.8	26.8	17.8*	NE
		f	29.2	33.6	31.4	20.4	NE

* significantly different from control, p<0.01

b both sexes combined

NR not recorded

NE not evaluated

Conclusions:

(3-Chloropropyl)trimethoxysilane has been tested for clastogenicity in a valid in vivo micronucleus study, according to a protocol similar to OECD Test Guideline 474 and in compliance with GLP. (3-Chloropropyl)trimethoxysilane did not produce significant, treatment-related increases in the incidence of micronucleated polychromatophilic erythrocytes among male or female Swiss-Webster mice assessed at 30, 48 or 72 hours . It is concluded that the test substance is negative for the induction of micronuclei in peripheral erythrocytes of mice under the conditions of the test after treatment with a single dose by intraperitoneal injection. Therefore, (3-chloropropyl)trimethoxysilane was not considered to be an inducer of micronuclei in male or female Swiss-Webster mice under the conditions of the in vivo assay.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Additional information

Measured in vitro genotoxicity studies are available for mutagenicity in bacterial and mammalian cells. Where there was more than one result for an endpoint the most reliable study available was chosen as key study. Where there was more than one reliable study, the most recent study was selected. The results of the key in vitro studies were in agreement.

(3-Chloropropyl)trimethoxysilane has been tested for mutagenicity in a valid gene mutation study in bacterial strains S. typhimurium TA98, TA100, TA1535, TA1537, TA1538, TA102 and E. coli WP2 uvr A with and without metabolic activation, conducted according to a protocol similar to OECD Test Guideline 471 and in compliance with GLP. A dose-dependent increase in the number of revertants was observed in S. typhimurium strains TA100 and TA1535 with and without metabolic activation, and in strain TA98 in the absence of metabolic activation. It is concluded that (3-chloropropyl)trimethoxysilane is positive for mutagenicity in bacteria under the conditions of this test (Dow Corning Corporation, 1993).

(3-Chloropropyl)trimethoxysilane has been tested for mutagenicity to bacteria in a valid gene mutation study in bacterial strains Salmonella typhimurium TA-98, TA-100, TA-1535 and TA-1537 and Escherichia coli/WP2 uvrA with and without metabolic activation, conducted according to EEC Directive No. L251 and in compliance with GLP. A dose-dependent increase in the number of revertants was observed in Salmonella typhimurium strains TA-1535, TA-1537 and TA-100 with and without metabolic activation. No dose-dependent increase in the number of revertants was seen in Salmonella typhmurium TA-98 and Escherichia coli/WP2 uvrA with and without metabolic activation. Appropriate positive and solvent controls were included and gave the expected results. It is concluded that (3-chloropropyl)trimethoxysilane is positive for mutagenicity in bacteria under the conditions of this test (Dow Corning Corporation, 1990a).

(3-Chloropropyl)trimethoxysilane has been tested for mutagenicity to bacteria in a valid gene mutation study in bacterial strains Salmonella typhimurium TA 98, TA 100, TA 1535, TA 1537, and TA 1538 with and without metabolic activation, conducted according to EU Method B.13/14 (Mutagenicity - Reverse Mutation Test Using Bacteria) and in compliance with GLP. A dose-dependent increase in the number of revertants was observed in Salmonella typhimurium TA 1535 with and without metabolic activation. No dose-dependent increase in the number of revertants was seen in Salmonella typhmurium TA 98, TA 100, TA 1537, and TA 1538 with and without metabolic activation. It is concluded that (3-chloropropyl)trimethoxysilane is positive for mutagenicity in bacteria under the conditions of this test (Huls AG, 1993).

(3-Chloropropyl)trimethoxysilane has been tested for mutagenicity to bacteria in a valid gene mutation study in bacterial strains Salmonella typhimurium TA-98, TA-100, TA-1535 and TA-1537 and Escherichia coli/WP2 uvrA with and without metabolic activation, conducted according to OECD Test Guideline 471 and in compliance with GLP. A dose-dependent increase in the number of revertants was observed in Salmonella typhimurium strains TA-1535, TA-1537 and TA-100 both with and without activation and in TA-98 with activation. No dose-dependent increase in the number of revertants was seen in the rest of the bacterial strains with and without metabolic activation. Appropriate positive and solvent controls were included and gave the expected results. It is concluded that (3-chloropropyl)trimethoxysilane is positive for mutagenicity in bacteria under the conditions of this test (Dow Corning Corporation, 1990b).

(3-Chloropropyl)trimethoxysilane has been tested for mutagenicity to bacteria in a valid gene mutation study in bacterial strains Salmonella typhimurium TA-98, TA-100, TA-1535 and TA-1537 and Escherichia coli/WP2 uvrA with and without metabolic activation, conducted according to a protocol similar to OECD Test Guideline 471 and in compliance with GLP. A dose-dependent increase in the number of revertants was observed in Salmonella typhimurium strains TA-1535, TA-1537 and TA-100 both with and without activation. No dose-dependent increase in the number of revertants was seen in Salmonella typhmurium TA-98 and Escherichia coli/WP2 uvrA with and without metabolic activation. Appropriate positive and solvent controls were included and gave the expected results. It is concluded that (3-chloropropyl)trimethoxysilane is positive for mutagenicity in bacteria under the conditions of this test (Dow Corning Corporation, 1990c).

(3-Chloropropyl)trimethoxysilane has been tested for mutagenicity to bacteria in a valid gene mutation study in bacterial strains Salmonella typhimurium TA-98, TA-100, TA-1535, TA-1537 and TA-1538 with and without metabolic activation, conducted according to a protocol similar to OECD Test Guideline 471 but pre-dates GLP compliance. No dose-dependent increase in the number of revertants was seen any of the test strains with and without metabolic activation. Appropriate positive and solvent controls were included and gave the expected results. It is concluded that (3-chloropropyl)trimethoxysilane is negative for mutagenicity in bacteria under the conditions of this test (Dow Corning Corporation, 1977).

(3-Chloropropyl)trimethoxysilane has been tested for mutagenicity in a reliable mammalian mutagenicity study in L5178Y mouse lymphoma cells with and without metabolic activation, conducted according to a protocol similar to OECD Test Guideline 476 and in compliance with GLP. The test material was considered to be negative for mutagenicity when tested without metabolic activation and positive when tested with metabolic activation. (3-Chloropropyl)trimethoxysilane has been concluded to be positive for mutagenicity in mammalian cells under the conditions of the study (Dow Corning Corporation, 1995).

(3-Chloropropyl)trimethoxysilane has been tested in a valid in vivo micronucleus study, according to a protocol similar to OECD Test Guideline 474 and in compliance with GLP.  (3-Chloropropyl)trimethoxysilane did not produce significant, treatment-related increases in the incidence of micronucleated polychromatophilic erythrocytes among male or female Swiss-Webster mice assessed at 30, 48 or 72 hours. In addition to systemic toxicity, the test substance induced very clear cytotoxicity to bone marrow in males, with the PCE/NCE ratio decreased by almost 50% in high-dose males, demonstrating that the target tissue was exposed to the test substance. It is concluded that the test substance is negative for the induction of micronuclei in peripheral erythrocytes of mice under the conditions of the test after treatment with a single dose by intraperitoneal injection. Therefore, (3-chloropropyl)trimethoxysilane was not considered to be genotoxic in male or female Swiss-Webster mice under the conditions of the in vivo assay (BRRC, 1993).

(3-Chloropropyl)trimethoxysilane has been tested in a 90-day inhalation repeated dose toxicity study incorporating in vivo micronucleus assessment, conducted according to OECD Test Guideline 413 and in compliance with GLP. No biologically significant increase in the number of micronucleated PCEs was observed. The PCE/NCE ratio was not affected by exposure to the test substance, so exposure of the target tissue could not be confirmed. (Dow Corning Corporation, 1993).

The positive results in the in vitro mutagenicity assays in bacteria and in mammalian cells indicated a potential for mutagenicity. The potential for genetic toxicity observed in vitro was not confirmed when the substance was tested in an in vivo micronucleus assay. The micronucleus assay is known to detect mutagens as well as clastogens (REF).

Justification for classification or non-classification

Based on the negative result in the available in vivo micronucleus assay, known to detect mutagens, the positive results in the in vitro mutagenicity assays in bacteria and in mammalian cells were not confirmed. Therefore, it is concluded that (3-chloropropyl)trimethoxysilane does not meet the criteria for classification for mutagenicity according to Regulation (EC) No 1272/2008.