Trichloro(propyl)silane

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 activation in all strains tested (OECD TG 471) (Laboratory of Pharmacology and Toxicology, 2002)
Cytogenicity in mammalian cells: read-across from analogous substance trichloro(methyl)silane (CAS 75-79-6): negative in L5178Y mouse lymphoma cells with and without activation (similar to OECD TG 473) (Litton Bionetics 1978)
Mutagenicity in mammalian cells: read-across from analogous substance trichloro(methyl)silane (CAS 75-79-6): negative in L5178Y mouse lymphoma cells (similar to OECD TG 476) (Litton Bionetics 1978)

The selected key study for bacterial mutagenicity was the more reliable of the two studies available. It was conducted according to an appropriate OECD guideline and under GLP. The mammalian studies are the more reliable of the available studies for the surrogate substance. They were conducted according to protocols that are similar to appropriate OECD guidelines. They were not conducted under 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:

2002-03-04 to 2002-09-24

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

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:

S. typhimurium TA 102

Metabolic activation:

with and without

Metabolic activation system:

Aroclor induced rat liver S9

Test concentrations with justification for top dose:

31.6-3160 µg/plate

Vehicle / solvent:

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

- Justification for choice of solvent/vehicle: Solvent is not harmful to bacteria

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

sodium azide

Remarks:

TA 1535, TA 100 (without activation)

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:

methylmethanesulfonate

Remarks:

TA 102 (without activation)

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

cyclophosphamide

Remarks:

TA 98, TA 102, TA 1537 (with 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-anthracene amide

Remarks:

TA 98, TA 102, TA 1537 (with activation)

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar, standard plate incorporation method, preincubation method

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

SELECTION AGENT (mutation assays): histidine deficient agar

NUMBER OF REPLICATIONS: cells were plated in triplicate; the experiment was repeated using the pre-incubation method.

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

ACTIVATION:
Aroclor induced rat liver S9 (protein content 32.92 mg/ml, cytochrome P-450: 0.32 nmol/mg) was added to S9 mix so that the mix contained 5% S9. glucose-6-phophate and NADP were added as co-factors. 0.5 ml S9 mix was added to 2 ml of top agar to a total volume of 2.7 ml. Final concentration S9 in agar was therefore approximately 1%.

Evaluation criteria:

The number of revertants is significantly increased compared with the solvent control to at least 2 fold of the solvent control for TA98, TA100 and TA102 and 3 fold of the solvent control for TA 1535 and TA1537 in both independent experiments. Positive results have to be reproducible and the histidine independence of the revertants has to be confirmed by streaking random samples on histidine free agar plates.

Statistics:

MANN and WHITNEY and Spearman's rank correlation used.

Key result

Species / strain:

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

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

3160 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 102

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

3160 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

See tables 2-4.

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

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

	TA100
Conc. (µg/plate)	Plate 1	Plate 2	Cytotoxic (yes/no)
0*	133	142	No
0.316	122	143	No
1	141	145	No
3.16	149	136	No
10	120	129	No
31.6	105	128	No
100	108	106	No
316	103	111	No
1000	134	133	No
3160	104	112	Yes
5000	131	109	Yes

*solvent control with DMSO

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

	TA98			TA100			TA102
Conc. (µg/plate)	— MA	+ MA	Cytotoxic (yes/no)	— MA	+ MA	Cytotoxic (yes/no)	— MA	+ MA	Cytotoxic (yes/no)
0*	28.3	29.3	No	163	146.7	No	288	286.3	No
31.6	32	30.3	No	142.7	158.7	No	281	284.7	No
100	28.3	36.7	No	153	147.7	No	290.7	279.3	No
316	33.7	34	No	147.7	162.7	No	276.3	299.7	No
1000	34	38	No	158.3	146.3	No	297.3	292.7	No
3160	39.3	35	Yes	164	156.7	Yes	295.7	273.3	Yes
Positive control	1003	994	No	1312.3	1298.7	No	1313.7	1305	No

*solvent control with DMSO

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

	TA1535			TA1537
Conc. (µg/plate)	— MA	+ MA	Cytotoxic (yes/no)	— MA	+ MA	Cytotoxic (yes/no)
0*	12	12.7	No	4.7	6	No
31.6	13.7	11.7	No	3	7	No
100	11.7	13	No	5.3	6.3	No
316	12.3	12	No	5	7.7	No
1000	11	12	No	7	8	No
3160	11.7	11	Yes	8.3	9	Yes
Positive control	773.3	780	No	780	783.7	No

*solvent control with DMSO

Table 4: Experiment 2 Preincubation Number of revertants per plate (mean of 3 plates)

	TA98			TA100			TA102
Conc. (µg/plate)	— MA	+ MA	Cytotoxic (yes/no)	— MA	+ MA	Cytotoxic (yes/no)	— MA	+ MA	Cytotoxic (yes/no)
0*	33	41.3	No	117.7	141.7	No	274.3	298.7	No
31.6	45	43.7	No	115	138.7	No	278.3	272.7	No
100	37.7	42	No	132	138	No	274.3	279.7	No
316	36.3	38.7	No	133.7	141.7	No	298.7	265	No
1000	34	44.3	No	120.3	145	No	268.3	278	No
3160	0	0	yes	0	0	yes	0	0	yes
Positive control	1070	1059	No	1199.7	1211	No	1176.7	1214	No

*solvent control with DMSO

Table 4: Experiment 2 Preincubation Number of revertants per plate (mean of 3 plates)

	TA1535			TA1537
Conc. (µg/plate)	— MA	+ MA	Cytotoxic (yes/no)	— MA	+ MA	Cytotoxic (yes/no)
0*	11.7	11.3	No	3	3	No
31.6	12	10.7	No	2.3	4	No
100	11	11.3	No	3.3	3	No
316	11	12	No	3	4	No
1000	11	12	No	3	3.7	No
3160	0	0	yes	0	0	yes
Positive control	646.3	624.3	No	640.7	637.7	No

*solvent control with DMSO

Conclusions:

Trichloro(propyl)silane has been tested for mutagenicity to bacteria according to OECD TG 471 and under GLP conditions in Salmonella typhimurium strains TA 98, TA 100, TA 102, TA 1535 and TA 1537. No evidence of an increase in the number of revertants was observed for the test substance when tested up to cytotoxic concentrations with and without metabolic activation in any of the test strains in either the initial plate incorporation assay or the subsequent pre-incubation test. It is concluded that the test substance is negative for mutagenicity to bacteria under the conditions of test.

Reference 2

Endpoint:

in vitro cytogenicity / chromosome aberration 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 473 (In Vitro Mammalian Chromosome Aberration Test)

Deviations:

yes

Remarks:

only 50 cells scored for aberrations, reporting has less detail than current guideline, no longer term exposure, no. of cells evaluated does not comply with current guideline

Principles of method if other than guideline:

Litton Bionetics standard procedure: Screening Program for the Identification of Potential Mutagens and Carcinogens. Protocol Number: DMT 100

GLP compliance:

no

Type of assay:

in vitro mammalian chromosome aberration test

Species / strain / cell type:

mouse lymphoma L5178Y cells

Metabolic activation:

with and without

Metabolic activation system:

mouse liver S9

Test concentrations with justification for top dose:

With metabolic activation: 0.02-0.32 µl/ml; without metabolic activation 0.01-0.16 µl/ml.

Vehicle / solvent:

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

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

Untreated negative controls:

yes

Remarks:

Medium

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

ethylmethanesulphonate

Remarks:

(without activation)

Untreated negative controls:

yes

Remarks:

Medium

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

N-dimethylnitrosamine

Remarks:

(with activation)

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium

DURATION
- Exposure time: 4 hours

- Expression time (cells in growth medium): 20 hours

NUMBER OF REPLICATIONS: 1 plates for each test concentration

NUMBER OF CELLS EVALUATED: 50 per plate

DETERMINATION OF CYTOTOXICITY

- Method: mitotic index

Key result

Species / strain:

mouse lymphoma L5178Y cells

Metabolic activation:

with and without

Genotoxicity:

negative

Remarks:

The very slight increase in incidence of aberrations reported is not considered to be biologically relevant.

Cytotoxicity / choice of top concentrations:

other: >= 0.32 µl/ml (equivalent to approximately 320 µg/ml)

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Table 2: Cytogenetic analysis (without activation)

Concentration µl/ml	Total No. Of Cells	Type / Frequency Aberrations per Cell (%)	No. Of Cells with 2+ Aberrations (%)	Mitotic Index (%)
Negative Control	50	1tb	0	2.2
Solvent Control	50	0	0	13.8
Positive Control	50	6tb, 1f, 1t, 6qr, 5tr, 1min	4	7.4
0.01	50	1qr	0	7.4
0.02	50	0	0	4.6
0.04	50	1f	0	5.2
0.08	50	1af, 1tb	0	8.4
0.16	50	0	0	5.4

Table 3: Cytogenetic analysis (with activation)

Compound and Concentration µl/ml	Total No. Of Cells	Type / Frequency Aberrations per Cell (%)	No. Of Cells with 2+ Aberrations (%)	Mitotic Index (%)
Negative Control	50	1tb, 1>	0	4
Solvent Control	50	0	0	9
Positive Control	50	6tb, 1f, 2t, 1tr, 1qr	1	4.4
0.02	50	1tb	0	4.4
0.04	50	2t, 1tr	1	10.8
0.08	50	1tb, 3f, 1tr	2	8
0.16	50	1tb, 1f, 1af, 1t	1	7.8
0.32	50	0	0	10.4

Key to type of aberration

tb	Chromatidbreak
f	Fragment
qr	Quadriradial
tr	Triradial
min	Minute chromosome
af	Acentricfragment
t	Translocation

 

Conclusions:

Trichloro(methyl)silane has been tested up to cytotoxic concentrations in a reliable assay according to a protocol that is similar to OECD TG 473. Appropriate concurrent negative and positive controls were included and the expected responses were observed. The number of cells with 2 or more aberrations increased very slightly under activation conditions, and no increase was observed at the highest dose tested. Trichloro(methyl)silane was considered by the authors of the study to have weak clastogenic activity that may be related to the cytotoxic properties of the test substance. It is concluded by the reviewer that the study does not demonstrate a biologically relevant effect.

Reference 3

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)

Deviations:

yes

Remarks:

non-activated mouse liver S9 mix used for activation

Principles of method if other than guideline:

Method: Litton Bionetics standard procedure: Screening Program for the Identification of Potential Mutagens and Carcinogens. Protocol Number : DMT 100

GLP compliance:

no

Type of assay:

mammalian cell gene mutation assay

Species / strain / cell type:

mouse lymphoma L5178Y cells

Metabolic activation:

with and without

Metabolic activation system:

Mouse liver S9

Test concentrations with justification for top dose:

Test 1: 0.02-0.32 µl/ml with metabolic activation, 0.01-0.16 µl/ml without metabolic activation; test 2: 0.04-0.32 µl/ml with metabolic activation, 0.04-0.32 µl/ml without metabolic activation

Vehicle / solvent:

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

- Justification for choice of solvent/vehicle: It is assumed by the reviewer that the solvent was chosen based on solubility properties and relative non-toxicity to bacteria

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

ethylmethanesulphonate

Remarks:

(without activation)

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

N-dimethylnitrosamine

Remarks:

(with activation)

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium

DURATION

- Exposure duration: 4 hours

- Expression time (cells in growth medium): 3 days

- Selection time (if incubation with a selection agent): 10 days

- Fixation time (start of exposure up to fixation or harvest of cells): 3 days 4 hours


SELECTION AGENT (mutation assays): THMG (thymidine, hypoxanthene, methoxotrexate, glycine)

NUMBER OF REPLICATIONS: 3 plates for each test concentration, assay repeated

DETERMINATION OF CYTOTOXICITY

- Method: relative total growth

Evaluation criteria:

A compound is considered mutagenic if:

- A dose response relationship is observed over three of the four dose levels employed

- The minimum increase at the high level of the dose response curve is at least 2.5 times greater than the solvent control value

- The solvent control data are within the normal range of spontaneous background for the TK locus.

Key result

Species / strain:

mouse lymphoma L5178Y cells

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

other: 0.32 µl/ml, equivalent to 320 µg/ml

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

The test substance did not induce mutation at the thymidine kinase locus with or without activation. Because there was very little toxicity observed in the non activation tests, the study was repeated. The repeat study produced greater levels of toxicity but was still negative for inducing mutations.

Table 2 :Results of Mammalian Mutagenicity assay (Test 1) with L5178Y/TK^+/- Mouse Lymphoma cells

Concentrationµl/ml	Mutant* Frequency	Mutant* Frequency	%Relative Growth.	%Relative Growth.	Cytotoxicity (yes/no)
	- MA	+ MA	- MA	+ MA	-
Solvent control	10.6	12.2	100	100	-
Negative control	12.2	10.3	123	64.1	-
Positive control	511.0	368.1	18.5	5.8	yes
0.01	8.0	-	134.2	-	no
0.02	10.8	23.1	140	72.5	no
0.04	7.3	10.5	134.1	99.1	no
0.08	11.3	14.1	118.1	101.2	no
0.16	18.1	17.6	112.4	94.1	no
0.32	-	12.9	-	45.7	yes

*Per 10⁶surviving cells

Solvent control with Ethanol

Table 3 : Results of Mammalian Mutagenicity assay (Test 2) with L5178Y/TK^+/-  Mouse Lymphoma cells

Concentrationµl/ml	Mutant* Frequency	Mutant* Frequency	%Relative Growth.	%Relative Growth.	Cytotoxicity (yes/no)
	— MA	+ MA	— MA	+ MA	-
Solvent Control	14	17	100	100	No
Negative Control	25.3	15.8	83.1	89.2	No
Positive Control	385	514	27	2.8	No
0.04	-	15.4	-	87.8	No
0.08	26.9	22.1	65.7	75.6	No
0.16	27.5	16.5	60.1	48	Yes
0.24	16.5	-	58.6	-	No
0.32	26.6	58	0.2	0.1	Yes

*Per 10⁶surviving cells

Solvent control with Ethanol

Conclusions:

Trichloro(methyl)silane was tested for mutagenicity in mammalian cells in a reliable and reproducible assay according to a protocol that is similar to OECD 476. Appropriate concurrent negative and positive controls were included and the expected responses were observed. There was no evidence of gene mutation up to cytotoxic concentrations. It is concluded that trichloro(methyl)silane is negative for the induction of mutation in mammalian cells under the conditions of the test.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Additional information

In a reliable bacterial mutagenicity study conducted according to OECD TG 471 and under GLP, no evidence of mutagenicity was observed with or without metabolic activation when trichloro(propyl)silane (CAS 141-57-1) was tested in Salmonella typhimurium strains TA 98, TA 100, TA 102, TA 1535 and TA1537 (Laboratory of Pharmacology and Toxicology, 2002). A further bacterial mutagenicity study confirmed also gave a negative result (Dow Corning Corporation, 1985).

The related substance trichloro(methyl)silane (CAS 75-79-6) has been tested up to cytotoxic concentrations in a reliable assay according to a protocol that is similar to OECD TG 473. Appropriate concurrent negative and positive controls were included and the expected responses were observed. The number of cells with 2 or more aberrations increased very slightly under activation conditions, and no increase was observed at the highest dose tested. The total number of cells with aberrations was not increased. Trichloro(methyl)silane was considered by the authors of the study to have weak clastogenic activity that may be related to the cytotoxic properties of the test substance. It is concluded by the reviewer that the study does not demonstrate a biologically relevant effect. (Litton Bionetics, 1978).

In a reliable in vitro mutagenicity study conducted according to a protocol similar to OECD TG 476, no evidence of mutagenicity was observed when trichloro(methyl)silane (CAS 75-79-6) was tested up to cytotoxic concentrations with or without metabolic activation in L5178Y mouse lymphoma cells (Litton Bionetics, 1978).

The most reliable studies were chosen as key. Where there was more than one reliable study, the most recent was selected. The results of all the studies are in agreement. 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, trichloro(propyl)silane is not classified for mutagenicity according to Regulation (EC) No 1272/2008.