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Administrative data

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

Referenceopen allclose all

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:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
no
GLP compliance:
yes (incl. certificate)
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.

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:
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.
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:
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.