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 activation in Salmonella typhimurium strains TA 98, TA 100, TA 1535, TA 1537 and E. coli WP2 uvrA (OECD TG 471) (Dow Corning Corporation (2003)).


Cytogenicity in mammalian cells: read-across from related substance triethoxy(octyl)silane, (CAS 2943-75-1): negative in Chinese hamster ovary cells (OECD TG 473)


Mutagenicity in mammalian cells: read-across from related substance triethoxy(octyl)silane, (CAS 2943-75-1): negative in mouse lymphoma L5178Y cells (OECD TG 476) (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:
2003-03-19 to 2003-04-01
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Version / remarks:
1997
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of assay:
bacterial reverse mutation assay
Target gene:
Histidine operon
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Species / strain / cell type:
E. coli WP2 uvr A
Metabolic activation:
with and without
Metabolic activation system:
Phenobarbital and Beta-Naphthoflavone induced rat liver S9
Test concentrations with justification for top dose:
3 µg/plate - 5000 µg/plate
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: Acetone

- 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) 10 µg/plate
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 10 µg/plate in TA 98, 50 µg/plate in TA 1537
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:
WP2 uvrA (without activation) 4 µl/plate
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: 2-aminoanthracene 2.5 µg/plate (TA 1535, TA 1537, TA 98, TA 100), 10 µg/plate (WP2 uvrA)
Remarks:
All strains (with activation)
Details on test system and experimental conditions:
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

DETERMINATION OF CYTOTOXICITY

- Method: Background lawn assessment, revertant colony counts
Evaluation criteria:
A result is considered 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 WP2 uvrA and 3-fold of the solvent control for TA 1535 and TA 1537 in both experiments.

A dose dependent increase is considered biologically relevant if the threshold is exceeded at more than one concentration. An increase exceeding the threshold at only one concentration is judged as biologically relevant if reproduced in an independent experiment.

Cytotoxicity is defined as a reduction in the number of colonies by >50% compared with the solvent control and/or a sparse background lawn.





Statistics:
No statistical evaluation of the data is required
Key result
Species / strain:
S. typhimurium TA 98
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
Key result
Species / strain:
S. typhimurium TA 100
Metabolic activation:
with
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
Key result
Species / strain:
S. typhimurium TA 100
Metabolic activation:
without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
5000 μg/plate
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Key result
Species / strain:
S. typhimurium TA 1535
Metabolic activation:
with
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
5000 μg/plate
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Key result
Species / strain:
S. typhimurium TA 1535
Metabolic activation:
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
Key result
Species / strain:
S. typhimurium TA 1537
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
5000 μg/plate
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Key result
Species / strain:
E. coli WP2 uvr A
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:

COMPARISON WITH HISTORICAL CONTROL DATA: With metabolic activation, the number of colonies did not quite reach the lower limit of historical control data in strain TA 1537, (negative and solvent control, exp 1), and in strain WP2 uvrA (negative control exp 1and 2, solvent control exp 1). Since these deviations are rather small, these effects are considered to be based upon biologically irrelevant fluctuations in the number of colonies.

Table 2:  Pre-toxicity test

 

TA98

TA100

TA1535

Conc.
(
µg/plate)

— MA

+ MA

Cytotoxic
(yes/no)

MA

+ MA

Cytotoxic
(yes/no)

MA

+ MA

Cytotoxic
(yes/no)

Negative control

23

29

No

108

107

No

10

12

No

0*

26

29

No

134

113

No

9

13

No

3

16

30

No

101

106

No

13

9

No

10

19

30

No

114

127

No

14

9

No

33

21

26

No

115

104

No

12

13

No

100

19

28

No

88

121

No

12

10

No

333

20

27

No

68

81

No

9

10

No

1000

16

26

No

76

84

No

9

10

No

2500

18

23

No

73

67

No

8

7

No

5000

17

20

No

52

58

Yes

5

6

Yes

Positive control

228

1495

No

1068

1629

No

697

211

No

*solvent control with acetone

Table 2:  Pre-toxicity test

 

TA1537

E. coli WP2 uvrA

Conc.
(
µg/plate)

— MA

+ MA

Cytotoxic
(yes/no)

— MA

+ MA

Cytotoxic
(yes/no)

Negative control

7

6

No

31

32

No

0*

4

5

No

29

31

No

3

3

5

No

28

25

No

10

5

5

No

28

34

No

33

5

5

No

27

33

No

100

4

7

No

32

34

No

333

3

4

No

30

27

No

1000

2

3

No

30

35

No

2500

3

3

No

31

32

No

5000

1

2

Yes

18

35

No

Positive control

50

226

No

804

215

No

*solvent control with acetone

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

 

TA98

TA100

TA1535

Conc.
(
µg/plate)

— MA

+ MA

Cytotoxic
(yes/no)

MA

+ MA

Cytotoxic
(yes/no)

MA

+ MA

Cytotoxic
(yes/no)

Negative control

23

29

No

108

107

No

10

12

No

0*

26

29

No

134

113

No

9

13

No

33

21

26

No

115

104

No

12

13

No

100

19

28

No

88

121

No

12

10

No

333

20

27

No

68

81

No

9

10

No

1000

16

26

No

76

84

No

9

10

No

2500

18

23

No

73

67

No

8

7

No

5000

17

20

No

52

58

Yes

5

6

Yes

Positive control

228

1495

No

1068

1629

No

697

211

No

*solvent control with acetone

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

 

TA1537

E. coli WP2 uvrA

Conc.
(
µg/plate)

— MA

+ MA

Cytotoxic
(yes/no)

— MA

+ MA

Cytotoxic
(yes/no)

Negative control

7

6

No

31

32

No

0*

4

5

No

29

31

No

33

5

5

No

27

33

No

100

4

7

No

32

34

No

333

3

4

No

30

27

No

1000

2

3

No

30

35

No

2500

3

3

No

31

32

No

5000

1

2

Yes

18

35

No

Positive control

50

226

No

804

215

No

*solvent control with acetone

Table 4: Experiment 2 Pre-incubation number of revertants per plate (mean of 3 plates)

 

TA98

TA100

TA1535

Conc.
(
µg/plate)

— MA

+ MA

Cytotoxic
(yes/no)

MA

+ MA

Cytotoxic
(yes/no)

MA

+ MA

Cytotoxic
(yes/no)

Negative control

30

38

No

148

184

No

20

18

No

0*

28

35

No

154

187

No

17

17

No

33

30

40

No

150

199

No

17

19

No

100

28

40

No

146

214

No

17

16

No

333

23

32

No

177

198

No

18

16

No

1000

24

37

No

195

216

No

17

17

No

2500

28

35

No

188

242

No

21

15

No

5000

31

44

No

207

215

No

16

17

No

Positive control

239

1465

No

1536

1207

No

1479

299

No

*solvent control with acetone

Table 4: Experiment 2 Pre-incubation number of revertants per plate (mean of 3 plates)

 

TA1537

E. coli WP2 uvrA

Conc.
(
µg/plate)

— MA

+ MA

Cytotoxic
(yes/no)

— MA

+ MA

Cytotoxic
(yes/no)

Negative control**

9

11

No

38

33

No

0*

9

11

No

36

38

No

33

10

13

No

28

35

No

100

7

11

No

39

36

No

333

5

14

No

42

46

No

1000

6

10

No

31

46

No

2500

6

11

No

41

46

No

5000

5

12

No

40

41

No

Positive control

77

227

No

444

346

No

*solvent control with acetone

Conclusions:
The substance RMS 808 MC has been tested according to OECD 471 and under GLP. No increase in the number of revertants was observed for the test substance tested up to cytotoxic or limit concentrations in any of the test strains either with or without metabolic activation in either the initial plate incorporation assay or the independent pre-incubation experiment . It is concluded that the test substance is not mutagenic 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:
1994.11.07 - 1997.12.24
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)
Deviations:
no
GLP compliance:
yes
Type of assay:
in vitro mammalian chromosome aberration test
Species / strain / cell type:
Chinese hamster Ovary (CHO)
Details on mammalian cell type (if applicable):
- Type and identity of media:
- Properly maintained: yes/no
- Periodically checked for Mycoplasma contamination: yes
- Periodically checked for karyotype stability: yes/no
- Periodically "cleansed" against high spontaneous background: yes/no
Metabolic activation:
with and without
Metabolic activation system:
Aroclor 1254 induced rat liver S-9
Test concentrations with justification for top dose:
0.016 - 157 µg/ml
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: ethanol
- Justification for choice of solvent/vehicle: no information provided
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
Remarks:
Ethanol
True negative controls:
no
Positive controls:
yes
Positive control substance:
benzo(a)pyrene
Remarks:
used with S9 metabolic activation 30 µg/ml
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
Remarks:
Ethanol
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: N-methyl-N-nitro-N-nitrosoguanidine (MNNG) dosed at 2 µg/ml
Remarks:
used without S9 activation
Details on test system and experimental conditions:
METHOD OF APPLICATION: in medium

DURATION
- Exposure duration: 6 hours with and without S9 metabolic activation or up to 24 and 48 hours without S9
- Expression time (cells in growth medium): 18 hours
- Fixation time (start of exposure up to fixation or harvest of cells):

SPINDLE INHIBITOR (cytogenetic assays): Colcemid
STAIN (for cytogenetic assays): 5% Giemsa

NUMBER OF REPLICATIONS: 2

NUMBER OF CELLS EVALUATED: 200 per dose level

DETERMINATION OF CYTOTOXICITY
- Method: mitotic index; cell growth inhibition

Statistics:
Fisher's exact test and the Cochran-Armitage test
Key result
Species / strain:
Chinese hamster Ovary (CHO)
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
at 20 µg/ml (_MA); 50 µg/ml (+MA)
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:



COMPARISON WITH HISTORICAL CONTROL

Chromosome aberration assay

Treatment µg/ml

S9 activation

Treatment /Harvest Time

Mitotic index*

Metaphase cells scored for aberrations

Cells with aberrations (200 cells evaluated)

Numerical      Structural

Negative control

    -

24

7.2

200

2.5

  0.5

Solvent control

    -

6/24

6.1

200

2.5

  0.5

A-137

 

 

 

 

 

 

 8.5

    -

6/24

6.8

200

1.0

  1.0

 11.3

    -

6/24

8.2

200

2.0

  0.5

15

    -

6/24

8.5

200

0.5

  2.0

20

    -

6/24

3.9

155

0.6

 0.0

Positive control

    -

6/24

5.2

200

1.5

27.0**

 

 

 

 

 

 

 

Negative control

    +

24

10.9

200

3.0

 0.5

Solvent control

    +

6/24

8.2

200

5.0

 0.5

A-137

 

 

 

 

 

 

21.3

    +

6/24

9.5

200

5.0

 0.5

28.3

    +

6/24

9.4

200

5.0

 0.0

37.6

    +

6/24

6.6

200

8.0

 1.5

50

    +

6/24

3.2

200

3.5

 1.0

Positive control

    +

6/24

3.0

200

8.5

43.0**

 

 

 

 

 

 

 

Negative control

    -

24

12.1

200

0.5

 0.5

Solvent control

    -

24/24

9.1

200

0.0

 1.0

A-137

 

 

 

 

 

 

8.5

    -

24/24

7.6

200

0.0

 1.0

11.3

    -

24/24

11.6

200

1.0

 1.0

15

    -

24/24

11.7

200

1.5

 1.0

20

    -

24/24

 1.7

  37

0.0

 0.0

Positive control

    -

24/24

 5.9

200

1.5

20.5**

 

 

 

 

 

 

 

Negative control

    -

48

5.0

200

0.0

 0.5

Solvent control

    -

48/48

4.0

200

0.0

 1.5

A-137

 

 

 

 

 

 

8.5

    -

48/48

4.1

200

0.0

 2.0

11.3

    -

48/48

3.1

200

0.0

 0.0

15

    -

48/48

2.0

200

1.0

 0.0

20

    -

48/48

2.0

200

0.5

 2.0

Positive control

    -

48/48

2.2

200

1.0

18.0**

* Number of cells evaluated for MI not indicated in report.

** Aberration frequency statistically significant

Conclusions:
Triethoxyoctylsilane has been tested in a reliable in vitro cytogenetic assay according to OECD TG 473 and under GLP. The test substance did not induce statistically and biologically significant increases in the chromosomal aberration frequency of CHO (chinese hamster ovary) cells. It is concluded that the test substance is negative for the induction of chromosome aberrations (not clastogenic) in vitro under the conditions of the test.

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:
OECD Guideline 476 (In Vitro Mammalian Cell Gene Mutation Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method B.17 (Mutagenicity - In Vitro Mammalian Cell Gene Mutation Test)
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 870.5300 - In vitro Mammalian Cell Gene Mutation Test
Deviations:
no
Qualifier:
according to
Guideline:
other: IWGT Recommendations
Deviations:
no
GLP compliance:
yes (incl. certificate)
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

105000

115000

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:
Triethoxyoctylsilane has been tested for mutagenicity to mammalian cells in a reliable study conducted according to OECD TG 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 bacteria under the conditions of the test.
Executive summary:

The test item Triethoxyoctylsilane was assessed for its potential to induce mutations at the mouse lymphoma thymidine kinase locus using the cell line L5178Y.

The selection of the concentrations used in the main experiments was based on data from the pre-experiments. In Experiment I 10.0 mM (with and without metabolic activation) was selected as the highest concentration. In Experiment II 10.0 mM (with metabolic activation) and 0.20 mM (without metabolic activation) were selected as the highest concentrations. Experiment I with and without metabolic activation and Experiment II with metabolic activation were performed as a 4 h short-term exposure assay. Experiment II without metabolic activation was performed as a 24 h long-term exposure assay.

THF was used as solvent (0.35% THF v/v in the samples). After adding the THF stock solution to cell culture medium precipitate formed.

The test item was investigated at the following concentrations:

Experiment I

with and without metabolic activation:

0.1, 0.2, 0.5, 1.0, 2.5, 5.0, 7.5 and 10.0 mM

Experiment II

with metabolic activation:

0.15, 0.3, 0.7, 2.0, 4.0, 6.0, 8.0 and 10.0 mM

and without metabolic activation:

0.001, 0.002, 0.005, 0.01, 0.02, 0.05, 0.10 and 0.20 mM

Precipitation of the test item was noted in Pre-experiment Iwith and without metabolic activation, Pre-experiment II without metabolic activation, Experiment I with and without metabolic activation and in Experiment II with metabolic activation.

In Experiment I with metabolic activation the relative total growth (RTG) was 74.3% for the highest concentration (10.0 mM) evaluated. At two concentrations (1.0 mM and 2.5 mM) growth inhibition was observed with a RTG of 63.7% and 67.1%, respectively. However, considering all evaluated concentrations this effect showed no concentration relationship. The highest concentration evaluated without metabolic activation was 10.0 mM with a RTG of 14.6%. The Experiment without metabolic activation displayed a concentration related decrease in RTG starting at 1.0 mM with a RTG of 49.2%.

In Experiment II with metabolic activation the relative total growth (RTG) was 76.4% for the highest concentration (10.0 mM) evaluated. At two concentrations (2.0 mM and 6.0 mM) growth inhibition was observed with a RTG of 42.3% and 58.9%, respectively. However, considering all evaluated concentrations this effect showed no concentration relationship. The highest concentration evaluated without metabolic activation was 0.20 mM with a RTG of 0.9%. Due to high cytotoxicity the highest concentration was not considered for evaluation of mutagenicity. Experiment II without metabolic activation displayed a concentration related decrease in RTG starting at 0.1 mM with a RTG of 16.8%.

In Experiments I and II no biologically relevant increase of mutants were found after treatment with the test item (with and without metabolic activation).The Global Evaluation Factor (GEF; defined as the mean of the negative/vehicle mutant frequency plus one standard deviation; data gathered from ten laboratories) was not exceeded by the induced mutant frequency at any concentration.

No dose-response relationship was observed in Experiment I with metabolic activation and in Experiment II with and without metabolic activation. In Experiment I without metabolic activation a dose-response relationship was observed in the higher concentrations.

Additionally, in Experiments I and II colony sizing showed no clastogenic effects induced by the test item under the experimental conditions (with and without metabolic activation).

EMS, MMS and B[a]P were used as positive controls and showed distinct and biologically relevant effects in mutation frequency. Additionally, MMS and B[a]P significantly increased the number of small colonies, thus proving the efficiency of the test system to indicate potential clastogenic effects.

This study is classified as acceptable. This study satisifes the requirements for Test Guidelines OPPTS 870.5300, OECD 476 forin vitromutagenicity (mammalian forward mutation) data.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (negative)

Genetic toxicity in vivo

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

Data are available for trimethoxy(octyl)silane (CAS 3069-40-7) from a reliable in vitro study for bacterial mutagenicity (Dow Corning Corporation 2003). An additional bacterial mutagenicity study is also available (Anawa Bioservice, 1996). The results of both experiments were in agreement. No further data are available for the registered substance, however, reliable data are available for the related substance triethoxy(octyl)silane, CAS 2943-75-1 from in vitro studies on cytogenicity and mutagenicity to mammalian cells. Both the structurally-analogous substance, triethoxy(octyl)silane, CAS 2943 -75 -1 and the registered substance, trimethoxy(octyl)silane, CAS 3069-40-7, hydrolyse to octylsilanetriol. Hydrolysis is likely to occur under the conditions of the studies and also in vivo. The other products of hydrolysis, methanol and ethanol, are not genotoxic OECD (2004a and OECD 2004b).

Triethoxy(octyl)silane was chosen as read-across substance as it has the same hydrolysis product as trimethoxy(octyl)silane, and neither substance has any functional groups that are associated with genetic toxicity. Additional information is given in a supporting report (PFA (2013aa)) attached in Section 13.

Trimethoxy(octyl)silane has been tested for mutagenicity to bacteria in a study conducted according to OECD 471 and in compliance with GLP (Dow Corning Corporation (2003)). No increase in the number of revertants was observed for the test substance tested up to cytotoxic or limit concentrations in any of the test strains either with or without metabolic activation in either the initial plate incorporation assay or the independent pre-incubation experiment. Appropriate solvent and positive controls were included and gave expected results. It is concluded that the test substance is not mutagenic to bacteria under the conditions of the test.

Additional evidence for lack of mutagenicity to bacteria is available from a study conducted according to a protocol similar to OECD TG 471 (Anawa Bioservice, 1996). No evidence of mutagenicity was observed with or without metabolic activation when trimethoxyoctylsilane was tested in Salmonella typhimurium strains TA98, TA 100, TA 1535, TA1537 and TA 1538.

In a cytogenicity study conducted according to OECD TG 473 and under GLP, no evidence of the induction of chromosome aberration was observed when the analogous substance, triethoxy(octyl)silane, was tested with or without metabolic activation in CHO K1 cells (MA Bioservices 1997).

The structural analogue triethoxy(octyl)silane has been tested for mutagenicity to mammalian cells in a reliable study conducted according to OECD TG 476 and in compliance with GLP (BSL Bioservice, 2012). 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. It is concluded that the test substance is negative for mutagenicity to bacteria under the conditions of the test.

There is no justification from in vitro results for testing in vivo.


Justification for classification or non-classification

Based on the available in vitro genotoxicity data, trimethoxy(octyl)silane is not classified for mutagenicity according to Regulation (EC) No 1272/2008.