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Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Information is available from a reliable bacterial mutagenicity study and a chromosome aberration assay for triethoxy(phenyl)silane (CAS 780-69-8). Reliable data are available for mammalian cell gene mutation for the structural analogue substance trichloro(phenyl)silane (CAS 98-13-5).

Gene mutation (Bacterial reverse mutation assay / Ames test) (OECD TG 471, GLP, RL1): negative with and without activation in all strains tested (Wacker, 2002)
Cytogenicity in mammalian cells (OECD TG 473, GLP, RL1): negative with and without metabolic activation in V79 cells (OECD TG 473, GLP, RL1) (BSL, 2012).
Mutagenicity in mammalian cells (CAS 98-13-5) (similar to OECD TG 476, GLP, RL1): negative in L5178Y mouse lymphoma cells (Reconcile, 2010)

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:
22 Mar - 30 May 2002
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
Type of assay:
bacterial reverse mutation assay
Target gene:
his operon
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:
cofactor supplemented post-mitochondrial fraction (S9 mix), prepared from the livers of rats treated with Aroclor 1254
Test concentrations with justification for top dose:
See table 1
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: abs. ethanol
- Justification for choice of solvent/vehicle: Solvent chosen due to solubility properties and relative nontoxicity to bacteria.
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: Sodium azide (TA 1535, TA 100); 2-nitrofluorene (TA 98); 9-aminoacridine (TA 1537); ethyl methanesulphonate (TA 102); +S9: 2-anthracene amide (TA 98, TA 102, TA 1537); cyclophosphamide (TA 100, TA 1535)
Details on test system and experimental conditions:
METHOD OF APPLICATION: in agar (plate incorporation); preincubation

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

NUMBER OF REPLICATIONS: 3 plates for each test concentration

DETERMINATION OF CYTOTOXICITY
- Method: relative total growth

POSITIVE CONTROLS
Plate incorporation
-S9: Sodium azide (TA 1535: 770.3 µg/plate, TA 100: 1142.3 µg/plate); 2-nitrofluorene (TA 98: 648.3 µg/plate); 9-aminoacridine (TA 1537: 527 µg/plate); ethyl methanesulphonate (TA 102: 1171 µg/plate); +S9: 2-anthracene amide (TA 98: 618.7 µg/plate, TA 102: 1200 µg/plate, TA 1537: 557.7 µg/plate); cyclophosphamide (TA 100: 1094.7 µg/plate, TA 1535:728.7 µg/plate)

Preincubation
-S9: Sodium azide (TA 1535: 808.3 µg/plate, TA 100: 1145 µg/plate); 2-nitrofluorene (TA 98: 618.7 µg/plate); 9-aminoacridine (TA 1537: 653.3 µg/plate); methyl methanesulphonate (TA 102: 789.3 µg/plate); +S9: 2-anthracene amide (TA 98: 731.7 µg/plate, TA 102: 1125.3 µg/plate, TA 1537: 793.3 µg/plate); cyclophosphamide (TA 100: 1133 µg/plate, TA 1535: 891 µg/plate)


Evaluation criteria:
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 independant 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.
Species / strain:
S. typhimurium, other: TA 1535, TA 1537, TA 98 and TA 100
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
Scarce background lawn from 100 µg. >50% reduction in revertants from 316 µg.
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 102
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
Scarce background lawn from 100 µg. >50% reduction in revertants from 316 µg.
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid
Additional information on results:
See tables 1-4

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


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*

118

122

No

0.316

108

136

No

1

112

129

No

3.16

127

100

No

10

108

113

No

31.6

120

112

No

100#

135

216

Yes

316#

105

0

Yes

1000#

149

139

Yes

3160

0

0

Yes

5000

0

0

Yes

*solvent control with Abs. ethanol

#colonies may represent pinpoint colonies rather than revertants

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*

34

40.7

No

126

121.7

No

258

268.3

No

3.16

29

36

No

119.7

123.7

No

238.3

307.7

No

10

31.3

41.7

No

119.7

112.3

No

252.7

290.3

No

31.6

30.7

38.3

No

133.3

113.3

No

255.3

282.3

No

100

30

32.7

No

110

109.3

No

254.3

269.7

No

316

33.7

37.7

No

127.7

127.3

Yes

254.7

304

No

Positive control

618.7

618.7

No

1142.3

1094.7

No

789.3

1200

No

*solvent control with Abs. ethanol

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*

15.7

15.3

No

10.7

10.3

No

3.16

18.7

11.3

No

6.7

9

No

10

17.7

15.3

No

7

11.7

No

31.6

16

16

No

8.3

10.3

No

100

15.7

21.7

No

7.7

10

No

316

12.7

12.7

Yes

9.7

11.3

Yes

Positive control

808.3

728.7

No

527

557.7

No

*solvent control with Abs. ethanol

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*

28.7

36

No

122.7

131

No

268

251.3

No

3.16

31

34

No

123.3

128

No

259.7

277.3

No

10

27.7

28.3

No

122

134.7

No

247.7

248

No

31.6

26.3

39

No

121

136.7

No

247.3

317.7

No

100

25

0

Yes

145.3

139.3

Yes

207.3

277.3

Yes

316

26

0

Yes

0

0

Yes

258

253.7

Yes

Positive control

648.3

731.7

No

1145

1133

No

1171

1125.3

No

*solvent control with Abs. ethanol

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*

15

14.3

No

11.7

13

No

3.16

11.3

13.7

No

12

12.3

No

10

12

12

No

16.7

12.7

No

31.6

9.7

14.7

No

11

14.3

No

100

0

0

Yes

0

0

Yes

316

0

0

Yes

0

0

Yes

Positive control

770.3

891

No

653.3

793.3

No

*solvent control with Abs. ethanol

Conclusions:
Interpretation of results: negative

Pronounced cytotoxicity (scarce background lawn) was noted at the concentrations of 100 µg up to 5000 µg of the test substance. Reduction of the number of revertants by more than 50% was noted at concentrations of 316, 3160 and 5000 µg of the test substance.

In a highly reliable test, conducted in accordance with OECD 471, under GLP, no mutagenic effect was observed for the test substance in any of the 5 test strains in two independent experiments without and with metabolic activation (plate incorporation or preincubation test). The test substance is not mutagenic in the test strains used.
Endpoint:
in vitro cytogenicity / chromosome aberration study in mammalian cells
Type of information:
experimental study
Adequacy of study:
key study
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)
Version / remarks:
adopted 1997
Deviations:
no
GLP compliance:
yes
Type of assay:
other: in vitro mammalian chromosome aberration test
Species / strain / cell type:
Chinese hamster lung fibroblasts (V79)
Metabolic activation:
with and without
Metabolic activation system:
Phenobarbital and β-Naphthoflavone activated rat liver S9
Test concentrations with justification for top dose:
Experiment 1:
with and without metabolic activation: 0.25, 0.5, 1, 2, 4, 5, 7.5, 10 mM
Experiment 2:
with metabolic activation: 0.05, 0.1, 0.2, 0.4, 0.6, 0.8, 1.0, 1.5, 2.5, 3.5, 5.0 mM
without metabolic activation: 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 0.75, 1.0, 1.5, 2.0 mM
Vehicle / solvent:
- Vehicle/solvent used: acetone
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
cyclophosphamide
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
ethylmethanesulphonate
Details on test system and experimental conditions:
METHOD OF APPLICATION: in medium

DURATION
- Exposure duration: 20 hours without activation (Exp. 2), 4 hours with activation (Exp. 1+2) and without activation (Exp. 1)
- Expression time (cells in growth medium): 0 or 16 hours
- Fixation time (start of exposure up to fixation or harvest of cells): 20 hours


SPINDLE INHIBITOR (cytogenetic assays): Colcemid was added (0.2 µg/mL culture medium) to the cultures 17.5 h after the start of the treatment.
STAIN (for cytogenetic assays): Giesma

NUMBER OF REPLICATIONS: duplicate cultures per concentration

NUMBER OF CELLS EVALUATED: At least 200 well spread metaphase plate per culture were scored for cytogenetic damage on coded slides.

DETERMINATION OF CYTOTOXICITY
- Method: mitotic index; other: relative well density

OTHER EXAMINATIONS:
- Determination of polyploidy: yes
- Determination of endoreplication: no data
Evaluation criteria:
A test item is classified as non-clastogenic if:
- the number of induced structural chromosome aberration in all scored dose groups is in the range of the laboratory’s historical control data range.
And/or
- No significant increase of the number of structural chromosome aberration is observed.

A test item is classified as clastogenic if:
- the number of induced structural chromosome aberration is not in the range of the laboratory’s historical control data range
and
- either a concentration-related or a significant chromosome increase of the number of structural chromosome is observed.
Species / strain:
Chinese hamster lung fibroblasts (V79)
Metabolic activation:
without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
0.5 mM
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid
Species / strain:
Chinese hamster lung fibroblasts (V79)
Metabolic activation:
with
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
2.5 mM
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid
Additional information on results:
TEST-SPECIFIC CONFOUNDING FACTORS
- Precipitation: In the main experiment no precipitation of the test item in culture at the end of treatment was observed either in the absence or the presence of S9 mix.

RANGE-FINDING/SCREENING STUDIES:
In a range finding pre-test mitotic index and cell density were examined as an indicator for cytotoxicity after treatment with up to 10 mM under the same conditions as in the main experiment. Clear toxic effects were observed after treatment with 10 mM test substance.

Table 1. Summary of results of the chromosome aberration study with triethoxyphenylsilane.

Test item

Concentration

Mitotic Index

Aberrant cells in %

 

[mM]

in %

with gaps

without gaps

Exposure period 4 h, fixation time 20 h, with S9 mix

Solvent (0.25%)

 

100

2.5

1.0

CPA (0.83 µg/l)

 

88

11.0

8.0

Test substance

1.5

63

2.5

1.5

2.5

47

2.5

1.5

3.5

41

1.0

1.0

Negative control

 

103

4.5

2.0

 

 

 

 

 

Exposure period 20 h, fixation time 20 h, without S9 mix

Solvent (0.25%)

 

100

1.5

1.0

EMS (400 µg/l)

 

85

12.0

10.5

Test substance

0.1

108

2.5

0.5

0.25

93

3.0

2.0

0.5

44

4.5

3.0

Negative control

 

90

4.5

2.0

Conclusions:
Interpretation of results: negative

In conclusion, it can be stated that under the applied conditions the test item triethoxyphenylsilane did not induce structural chromosomal aberrations in the V79 cell line. Therefore, trimethoxyphenylsilane is not considered to be clastogenic in this chromosome aberration test.
Endpoint:
in vitro gene mutation study in mammalian cells
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
Please refer to the attached justification below and the overall justification for grouping of substances attached in IUCLID Section 13.
Reason / purpose:
read-across source
Species / strain:
mouse lymphoma L5178Y cells
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
600 µg/ml
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid
Conclusions:
Interpretation of results: negative with and without activation

Executive summary:

An in vitro mammalian mutagenicity study is available from the structural analogue trichloro(phenyl)silane. In this test the structural analogue did not show any genotoxic potential and thus this is also estimated for triethoxy(phenyl)silane. As explained in the justification for type of information, the differences in molecular structure between the target and the source are unlikely to lead to differences in genetic toxicity that are higher than the typical experimental error of the test method.

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

Genetic toxicity in vivo

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

Details on read across justifications can be found in the attached justification in the respective target entry and in the overall justification for grouping of substances attached in IUCLID Section 13.

 

In a reliable test with triethoxy(phenyl)silane (CAS 780-69-8), conducted in accordance with OECD 471, under GLP, no mutagenic effect was observed for the test substance in any of the 5 test strains (TA 1535, TA 1537, TA 98, TA 100 and TA 102) in two independent experiments without and with metabolic activation (plate incorporation or preincubation test). The test substance was not mutagenic under the conditions of the test. However, pronounced cytotoxicity (scarce background lawn) was noted at the concentrations of 100 µg up to 5000 µg of the test substance. Reduction of the number of revertants by more than 50% was noted at concentrations of 316, 3160 and 5000 µg of the test substance.

 

Trichloro(phenyl)silane (CAS 98-13-5) has been tested in a reliable study according to OECD TG 476 and under GLP. No increase in mutant frequency was observed at any concentration from 300 to 1000 µg/ml without activation (4 hours treatment), from 200 to 900 µg/ml with activation (4 hours treatment) and without activation (24 hours treatment).Expected results were obtained with positive and negative controls. It is concluded that trichloro(phenyl)silane is negative for the induction of mutations in L5178Y cells under the conditions of the test.

 

In a key in vitro chromosome aberration (chinese hamster cell line) test conducted according to OECD 473 and GLP no effects on chromosome aberration were observed in the absence and presence of metabolic activation. Therefore, triethoxy(phenyl)silane is not considered to be clastogenic in this chromosome aberration assay.

 

In conclusion, based on the negative results in in vitro genotoxicity tests, triethoxyphenylsilane is considered to be not genotoxic, and therefore no classification is warranted. No in vivo data are available for triethoxy(phenyl)silane.

Justification for classification or non-classification

The available data on genetic toxicity of the registered substance do not meet the criteria for classification according to Regulation 1272/2008, and are therefore conclusive but not sufficient for classification.