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Toxicological information

Genetic toxicity: in vitro

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Administrative data

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

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1998
Report date:
1998

Materials and methods

Test guideline
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

Test material

Constituent 1
Chemical structure
Reference substance name:
Triethoxy(2,4,4-trimethylpentyl)silane
EC Number:
252-558-1
EC Name:
Triethoxy(2,4,4-trimethylpentyl)silane
Cas Number:
35435-21-3
Molecular formula:
C14H32O3Si
IUPAC Name:
triethoxy(2,4,4-trimethylpentyl)silane

Method

Species / strain
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.
Controlsopen allclose all
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.

Results and discussion

Test results
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

Any other information on results incl. tables

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

Applicant's summary and conclusion

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.