Registration Dossier

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 metabolic activation in all strains tested (OECD Test Guideline 471 and in compliance with GLP) (RCC Cytotest Cell Research, 1998).
Cytogenicity in mammalian cells: negative with and without metabolic in Chinese lung fibroblasts (V79) (OECD Test Guideline 473 and in compliance with GLP) (BSL Bioservice, 2001e).
Mutagenicity in mammalian cells: read across from structural analogue triethoxy(octyl)silane (CAS 2943-75-1): negative with and without metabolic activation in mouse lymphoma L5178Y cells (OECD Test Guideline 476 and in compliance with GLP) (BSL Bioservice, 2012).

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:
1998-03-24 to 1998-04-06
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, TA 100 and TA 102
Metabolic activation:
with and without
Metabolic activation system:
Phenobarbital and Beta-Naphthoflavone induced rat liver S9
Test concentrations with justification for top dose:
33-5000 µg/plate
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: DMSO

- Justification for choice of solvent/vehicle: 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:
sodium azide
Remarks:
TA 1535, TA 100 (without activation)
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: 4-nitro-o-phenylene-diamine
Remarks:
TA 1537, TA 98 (without activation)
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
methylmethanesulfonate
Remarks:
TA 102 (without activation)
Untreated negative controls:
yes
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:
ACTIVATION: Phenobarbital and beta-naphthoflavone induced rat liver S9 mix containing NADP as cofactor: Mix was 15% S9, 500 µl were mixed into a total volume of 2,700 µl prior to pouring giving a final concentration of approximately 1.2% S9.

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

DURATION

- Preincubation period: 60 minutes

- Expression time (cells in growth medium): 48 hours

NUMBER OF REPLICATIONS: 3 plates for each test concentration. The initial plate incorporation experiment was repeated using the preincubation method.

DETERMINATION OF CYTOTOXICITY
- Method: Background lawn evaluation, revertant colony counts
Evaluation criteria:
The test substance is considered positive if there is a reproducible dose related increase in revertants, or reproducible increase in one test concentration.

A result is positive if the number of revertants is significantly increased compared with the solvent control to at least 2-fold of the solvent control for TA 98, TA 100 and TA 102 and 3-fold of the solvent control for TA 1535 and TA 1537 in both experiments.

Cytotoxicity is defined as a reduction in the number of colonies compared with the solvent control and/or a sparse background lawn.
Key result
Species / strain:
S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity nor precipitates, but tested up to recommended limit concentrations
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
COMPARISON WITH HISTORICAL CONTROL DATA: Results were within range of historical control data

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

TA 98

TA 100

Concentration (μg/Plate)

Plate 1

+ MA

Plate 2

- MA

Cytotoxic (Yes/No)

Plate 1

+ MA

Plate 2

- MA

Cytotoxic (Yes/No)

Negative control*

41

21

No

148

137

No

0**

26

23

No

137

117

No

3

30

20

No

124

107

No

10

33

23

No

106

94

No

33

36

19

No

126

108

No

100

30

23

No

113

114

No

333

30

20

No

116

111

No

1000

36

28

No

153

117

No

2500

24

23

No

147

117

No

5000

34

16

No

156

118

No

Positive control

286

609

No

405

982

No

*negative control with water

**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)

Negative control*

21

41

No

137

148

No

192

249

No

0**

23

26

No

117

137

No

178

273

No

33

19

36

No

108

126

No

169

209

No

100

23

30

No

114

113

No

163

206

No

333

20

30

No

111

116

No

158

227

No

1000

28

36

No

117

153

No

169

234

No

2500

23

24

No

117

147

No

161

202

No

5000

16

34

No

118

156

No

196

280

No

Positive control

609

286

No

982

405

No

983

1153

No

*negative control with water

**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)

Negative control*

12

9

No

18

14

No

0**

15

10

No

14

14

No

33

20

14

No

15

17

No

100

19

11

No

12

12

No

333

23

11

No

13

13

No

1000

16

18

No

13

15

No

2500

17

14

No

12

13

No

5000

14

15

No

13

15

No

Positive control

1024

147

No

153

112

No

*negative control with water

**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)

Negative control*

29

52

No

159

156

No

279

245

No

0**

25

49

No

147

166

No

285

251

No

33

31

54

No

139

169

No

237

231

No

100

30

51

No

137

165

No

275

254

No

333

29

49

No

122

160

No

227

258

No

1000

30

49

No

139

166

No

222

252

No

2500

32

43

No

128

175

No

236

276

No

5000

28

51

No

134

157

No

231

243

No

Positive control

630

267

No

1236

688

No

1496

1049

No

*negative control with water

**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)

Negative control*

26

16

No

11

25

No

0**

29

13

No

11

22

No

33

22

18

No

10

24

No

100

21

16

No

9

30

No

333

22

16

No

7

23

No

1000

20

18

No

9

18

No

2500

21

11

No

9

16

No

5000

17

17

No

6

18

No

Positive control

847

121

No

128

126

No

*negative control with water

**solvent control with DMSO

Conclusions:
Triethoxy(2,4,4-trimethylpentyl)silane has been tested for mutagenicity to bacteria in a valid and reliable study conducted according to OECD Test Guideline 471 and in compliance with GLP. No mutagenic effect was observed for the test substance tested up to limit concentration in any of the Salmonella typhimurium strains TA 1535, TA 1537, TA 98, TA 100 and TA 102 in a plate incorporation experiment without and with metabolic activation. The result was confirmed in an independent pre-incubation assay. Appropriate positive, negative and solvent controls were included and gave expected results. It is concluded that the test substance is negative for mutagenicity to bacteria under the conditions of the test.
Endpoint:
in vitro cytogenicity / chromosome aberration study in mammalian cells
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2000-11-02 to 2001-02-06
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:
1997
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method B.10 (Mutagenicity - In Vitro Mammalian Chromosome Aberration Test)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EPA OPPTS 870.5375 - In vitro Mammalian Chromosome Aberration Test
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of assay:
in vitro mammalian chromosome aberration test
Species / strain / cell type:
Chinese hamster lung fibroblasts (V79)
Metabolic activation:
with and without
Metabolic activation system:
Beta-Napthoflavone and Phenobarbital induced rat liver S9
Test concentrations with justification for top dose:
Experiment 1, -S9: 500, 2000, 5000 µg/ml
Experiment 1, +S9: 250, 200, 5000 µg/ml
Experiment 2, -S9: 50, 200, 500 µg/ml
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: Cell culture medium. The test substance was prepared and diluted in cell culture medium. Freshly prepared solutions (applied within 1 h after preparation) were used.
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
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:
cyclophosphamide
Remarks:
with activation
Details on test system and experimental conditions:
ACTIVATION: S9 mix contained 0.75 mg/ml protein and NADP as cofactor. 50 µl were added to test organisms, test or control substance and medium in each chamber of Quadriperm dishes.

METHOD OF APPLICATION: in medium

DURATION

- Exposure duration: 4 hours with and without S9 (exp 1); 20 hours without S9 (exp 2)

- Expression time (cells in growth medium): 16 hours (exp 1); 20 hours (exp 2)

- Selection time (if incubation with a selection agent): 2 days

- Fixation time (start of exposure up to fixation or harvest of cells): 17.5 hours

SPINDLE INHIBITOR (cytogenetic assays): Colcemide

STAIN (for cytogenetic assays): Giesma

NUMBER OF REPLICATIONS: 2

NUMBER OF CELLS EVALUATED: At least 200 per concentration

DETERMINATION OF CYTOTOXICITY

- Method: mitotic index; relative total growth

OTHER EXAMINATIONS:

- Determination of polyploidy: determined in 100 cells per culture of each test group
Evaluation criteria:
A positive result is determined by a dose related increase in the number of cells with aberration, and a biologically relevant positive response for at least one of the test points.

The number of aberrations found in the negative control should be between 0 % and 4.5 %. The positive control should produce biologically relevant increases in the number of cells with structural chromosome aberrations.
Key result
Species / strain:
Chinese hamster lung fibroblasts (V79)
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
500 μg/ml (exp 2, 20 h treatment without activation)
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid
Additional information on results:
TEST-SPECIFIC CONFOUNDING FACTORS

- Precipitation: noted in experiment 2 at 5000 μg/ml, 500 μg/ml selected as top concentration for evaluation in that experiment.

COMPARISON WITH HISTORICAL CONTROL DATA: Results were within range of historical control data

Table 2: Results of chromosome analysis Experiment 1, 4h treatment without activation (total count from 2 cultures)

 

Solvent*

Control

Positive

Control

Low dose 500 μg/ml

Medium dose 2000 μg/ml

High dose 5000 μg/ml

Cytotoxicity

No

No

No

No

No

 

Mean

Chromatid aberrations

gaps

3

4

0

1

2

deletions

0

1

1

0

1

interchanges

0

21

0

1

2

Chromosome

gaps

-

-

-

-

-

deletions

0

0

0

0

0

interchanges

0

4

0

0

0

Mitotic index

100 %

103 %

140 %

116 %

86 %

Polyploidy

6

7

1.5

1

4

Endo reduplication

ND

ND

ND

ND

ND

 *Solvent control with culture medium

ND not determined

Table 3: Results of chromosome analysis Experiment 1, 4h treatment with activation (total count from 2 cultures)

 

Solvent*

Control

Positive

Control

Low dose 250 μg/ml

Medium dose 2000 μg/ml

High dose 5000 μg/ml

Cytotoxicity

No

No

No

No

No

 

Mean

Chromatid aberrations

gaps

2

4

4

2

0

deletions

0

1

0

0

0

interchanges

2

17

1

1

1

Chromosome

gaps

-

-

-

-

-

deletions

0

0

0

0

0

interchanges

0

0

0

0

0

Mitotic index

100 %

126 %

93 %

95 %

83 %

Polyploidy

3.5

5

3.5

3.5

2

Endo reduplication

ND

ND

ND

ND

ND

 *Solvent control with culture medium

ND not determined

Table 4: Results of chromosome analysis Experiment 2, 20h treatment without activation (total count from 2 cultures)

 

Solvent*

Control

Positive

Control

Low dose 50 μg/ml

Medium dose 200 μg/ml

High dose 500 μg/ml

Cytotoxicity

No

Yes

No

No

Yes

 

Mean

Chromatid aberrations

gaps

1

11

3

1

0

deletions

0

2

1

0

0

interchanges

0

35

0

0

0

Chromosome

gaps

-

-

-

-

-

deletions

0

0

0

0

0

interchanges

0

2

0

0

0

Mitotic index

100 %

51 %

91 %

85 %

29 %

Polyploidy

3.5

2.5

4.5

1.5

3

Endo reduplication

ND

ND

ND

ND

ND

 *Solvent control with culture medium

ND not determined

Conclusions:
Triethoxy(2,4,4-trimethylpentyl)silane has been tested for clastogenicity in a valid and reliable test performed according to OECD Test Guideline 473 and in compliance with GLP. The test substance did not induce structural chromosomal aberrations in the V79 Chinese hamster cell line with and without metabolic activation when tested up to limit concentrations. Appropriate solvent and postive controls were included and gave expected results. It is concluded that the test substance is negative for the induction of chromosome aberrations under the conditions of the test.
Endpoint:
in vitro gene mutation study in mammalian cells
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2011-12-21 to 2012-03-20
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 476 (In Vitro Mammalian Cell Gene Mutation Test)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method B.17 (Mutagenicity - In Vitro Mammalian Cell Gene Mutation Test)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EPA OPPTS 870.5300 - In vitro Mammalian Cell Gene Mutation Test
Deviations:
no
Qualifier:
according to guideline
Guideline:
other: IWGT Recommendations
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Remarks:
(Bayerisches Landesamt für Gesundheit und Lebensmittelsicherheit, Germany)
Type of assay:
mammalian cell gene mutation assay
Target gene:
Thymidine kinase
Species / strain / cell type:
mouse lymphoma L5178Y cells
Details on mammalian cell type (if applicable):
- Type and identity of media: RPMI
- Properly maintained: Yes
- Periodically checked for Mycoplasma contamination: yes
- Periodically "cleansed" against high spontaneous background: yes
Metabolic activation:
with and without
Metabolic activation system:
Liver S9 of Wistar Phenobarbital and ß-Naphthoflavone-induced rat liver S9 mix
Test concentrations with justification for top dose:
Pre-expt I: 0.2, 0.5, 2.5, 5.0, 7.5 and 10.0 mM (+/-MA); Pre-expt II: 0.01, 0.1, 1.0, 2.0, 5.0, 10.0 mM (-MA, 24 h exp); Expt I: 0.1, 0.2, 0.5, 1.0, 2.5, 5.0, 7.5 and 10.0 mM (+/-MA); Expt II: 0.15, 0.3, 0.7, 2.0, 4.0, 6.0, 8.0 and 10.0 mM (+MA); 0.001, 0.002, 0.005, 0.01, 0.02, 0.05, 0.10 and 0.20 mM (-MA)




Vehicle / solvent:
THF was used as solvent (0.35% THF v/v in the samples). To reach a final concentration of 0.35% THF v/v in the samples the test item stock solution was diluted in RPMI + 5% HS for short-term exposure or RPMI + 7.5% HS for long-term exposure. After adding the THF stock solution to cell culture medium precipitate formed.
The solvent was compatible with the survival of the cells and the activity of the S9 mix.
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
Remarks:
THF
True negative controls:
no
Positive controls:
yes
Positive control substance:
benzo(a)pyrene
Remarks:
with metabolic activation: 3.5 µg/mL
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
ethylmethanesulphonate
Remarks:
without metabolic activation: 200 µg/mL and 300 µg/mL
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
methylmethanesulfonate
Remarks:
without metabolic activation: 10 µg/mL
Details on test system and experimental conditions:
METHOD OF APPLICATION: dissolved in THF (0.35% THF v/v in the samples)
DURATION: 4 h (short-term exposure), 24 h (long-term exposure)
Expression time (cells in growth medium): 48 h
Selection time (if incubation with selection agent): about 14 days

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

ACTIVATION: S9 mix contained glucose-6-phosphate and NADP as co-factors, and sufficient S9 to give a final protein concentration in the cultures of 0.75 mg/ml
Evaluation criteria:
The test item is considered mutagenic if following criteria are met:
-The induced mutant frequency meets or exceeds the Global Evaluation factor (GEF) of 126 per 10^6 cells
- A dose-dependent increase in mutant frequency is detected.

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

Statistics:
The non-parametric Mann-Whitney test is applied to the mutation data to prove the dose groups for any significant difference in mutant frequency compared to the negative /solvent controls.
Key result
Species / strain:
mouse lymphoma L5178Y cells
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
RTG of 14.6% and 9.7% without metabolic activation.
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid

Pre-experiment for toxicity with and without metabolic activation

Concentration (mM)

Number of cells 4 h after treatment

Number of cells 24 h after treatment

Number of cells 48 h after treatment

Suspension growth

Relative suspension growth

 

+S9

-S9

+S9

-S9

+S9

-S9

+S9

-S9

+S9

-S9

Negative control

271000

278000

946000

948000

1600000

1570000

15.1

14.9

89.8

103.6

307000

356000

1050000

1150000

1510000

1540000

15.9

17.7

94.1

123.3

Solvent control

307000

256000

104000

807000

1560000

1570000

16.2

12.7

100.0

100.0

339000

313000

112000

101000

1560000

1590000

17.5

16.1

0.2

284000

271000

77000

593000

1540000

1480000

11.9

8.8

70.4

61.1

0.5

307000

252000

876000

377000

1490000

1190000

13.1

4.5

77.5

31.2

2.5

289000

220000

728000

186000

1620000

637000

11.8

1.9

70.0

13.3

5.0

316000

225000

798000

137000

1550000

286000

12.4

0.9

73.4

6.0

7.5 (P)

303000

271000

650000

239000

1590000

850000

10.3

2.6

61.3

17.8

10.0 (P)

305000

244000

728000

183000

1580000

481000

11.5

1.4

68.3

10.0

Summary: Experiment 1 and 2 with metabolic activation

 

Treatment (mM)

RTG (%)

MF (mutants/106cells)

IMF (mutants/106cells)

Precipitate

 

Negative control

103.5

125.6

/

-

 

98.1

/

-

 

Solvent control

100.0

135.2

/

-

 

/

-

 

0.1

72.3

142.3

7.2

-

Exp 1

0.2

73.5

143.3

8.1

-

 

0.5

84.9

97.1

-38.1

-

 

1.0

63.7

182.8

47.6

-

 

2.5

67.1

144.4

9.2

-

 

5.0

87.2

117.6

-17.6

-

 

7.5

78.1

154.8

19.6

-

 

10.0

74.3

130.3

-4.8

+

 

Positive control

38.4

918.4

783.2

-

 

 

 

 

 

 

 

Treatment (mM)

RTG (%)

MF (mutants/106cells)

IMF (mutants/106cells)

Precipitate

 

Negative control

98.9

116.5

/

-

 

111.8

/

-

 

Solvent control

100.0

116.7

/

-

 

/

-

 

0.15

111.4

105.1

-11.6

-

Exp 2

0.3

96.2

131.1

14.4

-

 

0.7

75.7

128.5

11.8

-

 

2.0

42.3

220.5

103.8

-

 

4.0

72.7

138.8

22.2

-

 

6.0

58.9

170.6

53.9

-

 

8.0

74.1

134.6

17.9

+

 

10.0

76.4

154.9

38.2

+

 

Positive control

50.5

1141.0

1024.3

-

MF - mutant frequency

IMF = induced mutant frequency

RTG = relative total growth

Summary: Experiment 1 and 2 without metabolic activation

 

Treatment (mM)

RTG (%)

MF (mutants/106cells)

IMF (mutants/106cells)

Precipitate

 

Negative control

122.0

142.0

/

-

 

129.6

/

-

 

Solvent control

100.0

144.3

/

-

 

/

-

 

0.1

100.3

177.2

32.9

-

Exp 1

0.2

87.3

157.4

13.0

-

 

0.5

98.4

186.0

41.6

-

 

1.0

49.2

190.1

45.7

-

 

2.5

37.8*

179.4

35.1

-

 

5.0

37.2

179.3

35.0

-

 

7.5

17.1

224.1

79.8

+

 

10.0

14.6

264.7

120.4

+

 

Positive control 1

75.1

817.6

673.2

-

 

Positive control 2

85.2

564.1

419.7

-

 

 

 

 

 

 

 

Treatment (mM)

RTG (%)

MF (mutants/106cells)

IMF (mutants/106cells)

Precipitate

 

Negative control

145.4

110.6

/

-

 

122.8

/

-

 

Solvent control

100.0

109.3

/

-

 

/

-

 

0.001

114.6

108.6

-0.8

-

Exp 2

0.002

99.3

94.7

-14.6

-

 

0.005

103.4

120.0

10.6

-

 

0.01

62.1

121.8

12.5

-

 

0.02

82.5

160.0

50.6

-

 

0.05

98.6

108.4

-0.9

-

 

0.10

16.8

173.0

63.6

-

 

0.20

0.9

119.1

9.7

-

 

Positive control 1

21.3

2373.6

2264.2

-

 

Positive control 2

14.7

1826.6

1717.3

-

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

Genetic toxicity in vivo

Description of key information

Micronucleus assay oral study in mouse: Negative (OECD Test Guideline 474 and in compliance with GLP) (BSL Bioservice, 2001)

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:
2000-11-27 to 2001-01-15
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of assay:
micronucleus assay
Species:
mouse
Strain:
NMRI
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS

- Source: Harlan Winkelman (D-33178, Borchen)

- Weight at study initiation: 24 - 42 g

- Assigned to test groups randomly: yes, under following basis: assigned and tail tagged by chance

- Housing: Macrolon Type III (Hereto, D-79302 Emmendingen)

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

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

- Acclimation period: minimum of 5 days


ENVIRONMENTAL CONDITIONS

- Temperature (°C): 19 - 25 ˚c

- Humidity (%): 49.5 - 61 %

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


IN-LIFE DATES: From: To: 15 January 2001
Route of administration:
oral: unspecified
Vehicle:
- Vehicle(s)/solvent(s) used: CMC (carboxymethyl cellulose)

- Justification for choice of solvent/vehicle: The vehicle was chosen because it is relatively non toxic to the test animals

- Lot/batch no. (if required): 36H0738
Details on exposure:
Route of exposure: Oral
Duration of treatment / exposure:
24 - 48 hours
Frequency of treatment:
The animals received the test item once orally.
Post exposure period:
Animals were sacrificed 24 - 48 h after treatment.
Dose / conc.:
2 000 mg/kg bw/day (nominal)
No. of animals per sex per dose:
five
Control animals:
yes, concurrent vehicle
Positive control(s):
- cyclophosphamide

- Justification for choice of positive control(s): standard guideline positive control

- Route of administration: oral

- Doses / concentrations: 10 ml/kg bw of 0.9 % solution in 0.9 % NaCl
Tissues and cell types examined:
Bone marrow
Details of tissue and slide preparation:
CRITERIA FOR DOSE SELECTION: limit dose

TREATMENT AND SAMPLING TIMES (in addition to information in specific fields): no further information

DETAILS OF SLIDE PREPARATION: centrifuged cells were suspended in a thin layer of FCS and smeared on a slide. The smears were air dried and stained with May-Grunwald (Merck, D-64293 Darmstadt) / Giemsa (Merck, D-64293 Darmstadt).

METHOD OF ANALYSIS: microscopic examination. 2000 PCE scored for incidence of polychromatic erythrocytes with micronuclei. Ratio of PCE / NCE was scored based on 1000 erythrocytes (PCE+NCE)
Evaluation criteria:
A test item is classified as mutagenic if it induces either a statistically significant dose related increase in the number of micronucleated polychromatic erythrocytes or a reproducible statistically significant positive response for at least one of the test points.
Statistics:
Micronuclei in 2000 PCE per animal were counted for each sex. NCE per 1000 PCE, Sum and Mean calculated for each sex.
Key result
Sex:
male/female
Genotoxicity:
negative
Toxicity:
no effects
Vehicle controls validity:
valid
Negative controls validity:
not applicable
Positive controls validity:
valid
Additional information on results:
See table 3

RESULTS OF DEFINITIVE STUDY

- Induction of micronuclei (for Micronucleus assay): negative

- Ratio of PCE/NCE (for Micronucleus assay): see table 3. The PCE/NCE ratio was unchanged in treated animals, so there is no evidence that the test substance reached the target tissue.

- Appropriateness of dose levels and route: appropriate dose and route

- Statistical evaluation: no statistically significant induction of micronuclei occurred.

Table 3: Results of in vivo micronucleus test

 

Vehicle

Control

Positive

Control

200 mg/kg

bw

1000 mg/kg

bw

2000 mg/kg

bw

2000 mg/kg

bw

Number of cells evaluated

2000

2000

2000

2000

2000

2000

Sampling time (h)

24

24

24

24

24

48

Number of erythrocytes

normo­chromatic

NR

NR

NR

NR

NR

NR

poly­chromatic

2000

2000

2000

2000

2000

2000

polychromatic with micronuclei

7 Male

5.2 Female

70.2 Male

42.4 Female

7.6 Male

9.2 Female

8.4 Male

4.8 Female

9.4 Male

5.0 Female

7.4 Male

4.8 Female

Ratio of erythrocytes

polychromatic / normochromatic

Male

1000/679.4

Female

1000/766.6

Male

1000/608

Female

1000/657.6

Male

1000/712.4

Female

1000/655.8

Male

1000/656.4

Female

1000/611.6

Male

1000/657

Female

1000/641.2

Male

1000/1064.6

Female

1000/511

polychromatic with micro­nuclei / normochromatic

NR

NR

NR

NR

NR

NR

 

Conclusions:
Triethoxy(2,4,4-trimethylpentyl)silane has been tested in a reliable in vivo mouse micronucleus assay according to OECD Test Guideline 474 and in compliance with GLP. No statistically significant increase in the number of cells with micronuclei was observed after oral administration of the limit dose of 2000 mg/kg bw. Appropriate positive and vehicle controls were included and gave expected results. The PCE / NCE ratio was slightly affected in treated males, indicating that the test item was of low toxicity to the target tissue. It is concluded that the test substance is negative for the induction in micronuclei under the conditions of the test.
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (negative)

Additional information

Information is available for the registered substance, triethoxy(2,4,4-trimethylpentyl)silane, from reliable studies for in vitro mutagenicity to bacteria and cytogenicity, and from an in vivo micronucleus assay. No information is available for the registered substance for in vitro mutagencicity to mammalian cells, however, data are available for the structural analogue, triethoxy(octyl)silane. See attachment to Section 13 for justification of read-across.

Triethoxy(2,4,4-trimethylpentyl)silane has been tested for mutagenicity to bacteria in a valid and reliable study conducted according to OECD Test Guideline 471 and in compliance with GLP. No mutagenic effect was observed for the test substance tested up to limit concentration in any of the Salmonella typhimurium strains TA 1535, TA 1537, TA 98, TA 100 and TA 102 in a plate incorporation experiment without and with metabolic activation. The result was confirmed in an independent pre-incubation assay. Appropriate positive, negative and solvent controls were included and gave expected results. It is concluded that the test substance is negative for mutagenicity to bacteria under the conditions of the test (RCC Cytotest Cell Research, 1998).

Triethoxy(2,4,4-trimethylpentyl)silane has been tested for clastogenicity in a valid and reliable test performed according to OECD Test Guideline 473 and in compliance with GLP. The test substance did not induce structural chromosomal aberrations in the V79 Chinese hamster cell line with and without metabolic activation when tested up to limit concentrations. Appropriate solvent and postive controls were included and gave expected results. It is concluded that the test substance is negative for the induction of chromosome aberrations under the conditions of the test (BSL Bioservice, 2001e).

An additional study for in vitro cytogenicity is available (Chemicals Evaluation and Research Institute, 2001b). This study reported a positive result in Chinese hamster fibrobalsts (V79 cells) in the absence of metabolic activation. The study report available for this result is an extended summary, and does not include tables of results, so there is not enough information to for a full independent assessment, but it is noted by the reviewer that the test substance was much more cytotoxic in the absence of activation, and the increase in abnormalities recorded was most marked at cytotoxic concentrations. In addition, the test substance is reported to be a mixture of 2,4,4-trimethylpentyltriethoxysilane and 5,5-dimethylhexyltriethoxysilane. In view of these factors, the availability of a reliable negative result in a similar study and the negative result in vivo, the study with the negative result was chosen as key.

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

Triethoxy(2,4,4-trimethylpentyl)silane has been tested in a reliable in vivo mouse micronucleus assay according to OECD Test Guideline 474 and in compliance with GLP.  No statistically significant increase in the number of cells with micronuclei was observed after oral administration of the limit dose of 2000 mg/kg bw. Appropriate positive and vehicle controls were included and gave expected results. The PCE / NCE ratio was slightly affected in treated males, indicating that the test item was of low toxicity to the target tissue. It is concluded that the test substance is negative for the induction in micronuclei under the conditions of the test (Bioservice, 2001).

Justification for classification or non-classification

Based on the available in vitro data and in vivo data on the registered substance and its structural analogue, triethoxy(2,4,4-trimethylpentyl)silane is not classified for mutagenicity according to Regulation (EC) No 1272/2008.