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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:
2001
Reliability:
1 (reliable without restriction)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2001
Report Date:
2001

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
JAPAN: Guidelines for Screening Mutagenicity Testing Of Chemicals
Version / remarks:
Ministry of Health and Welfare Ordinance No 1604: November 1, 1999 was followed as reference.
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
yes
Remarks:
duplicate not triplicate plates
GLP compliance:
no
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent

Method

Species / strainopen allclose all
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 5,6-benzoflavone activated rat liver S9
Test concentrations with justification for top dose:
156.3, 312.5, 625, 1250, 2500 and 5000 µg/plate
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: Acetone
- Justification for choice of solvent/vehicle: According to the sponsor, the test substance was insoluble in water and DMSO, whereas soluble and stable in acetone.
Controlsopen allclose all
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: 2-(2-Furyl)-3-(5-nitro-2-furyl) AF-2
Remarks:
TA98 (0.1 µg/plate), TA 100 and WP2uvrA (0.01 µg/plate) without metabolic activation
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
sodium azide
Remarks:
TA 1535 without metabolic activation: 0.5 µg/plate
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: 2-aminoanthracene - 2-AA
Remarks:
TA98 - 0.5 µg/plate, TA100 - 1.0 µg/plate, TA1535 and TA1537 - 2.0 µg/plate, WP2uvrA - 10.0 µg/plate with metabolic 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 metabolic activation: 80.0 µg/plate
Details on test system and experimental conditions:
METHOD OF APPLICATION: preincubation

ACTIVATION: S9 mix contained glucose-6-phosphate, NADPH and NADH as co-factors, 0.5 ml of S9 mix containing 10% S9 was added to 2 ml top agar, 0.05 ml of test solution and 0.1 ml tester strain, giving a final concentration of approximately 2% S9.

DURATION
- Preincubation period: Not stated in translated study report
- Exposure duration: 48 hr at 37ºC

SELECTION AGENT (mutation assays): histidine deficient agar

NUMBER OF REPLICATIONS: duplicate plates, test repeated

DETERMINATION OF CYTOTOXICITY
- Method: other: condition of background lawn
Evaluation criteria:
The test substance was judged positive when the number of revertant colonies in the test substance treated plate increased dose dependently and became 2-fold compared to that of the negative control.
Statistics:
The statistical analysis was not done for the judgement.

Results and discussion

Test resultsopen allclose all
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:
no cytotoxicity nor precipitates, but tested up to recommended limit concentrations
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
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 nor precipitates, but tested up to recommended limit concentrations
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid

Any other information on results incl. tables

Reverse mutation - dose determination test - pre-incubation method (mean of two plates)

Concentration µg/plate

Mean number of revertants/plate

TA 100

TA 1535

WP2uvrA

TA 98

TA 1537

-S9

+S9

-S9

+S9

-S9

+S9

-S9

+S9

-S9

+S9

Solvent control

131

127

10

11

27

30

23

27

10

15

5

124

139

10

8

23

29

22

36

9

15

10

122

121

11

11

27

26

21

32

11

14

50

110

111

17

14

30

29

19

34

10

16

100

117

121

10

11

30

34

17

38

9

15

500

130

126

11

17

27

35

19

31

10

15

1000

116

115

12

9

23

40

16

42

10

17

5000

116

119

13

13

33

31

19

33

12

17

Positive control

523

779

473

223

166

792

468

495

514

202

Pre-incubation test - revertants per plate (mean of two plates)

Concentration µg/plate

Mean number of revertants/plate

TA 100

TA 1535

WP2uvrA

TA 98

TA 1537

-S9

+S9

-S9

+S9

-S9

+S9

-S9

+S9

-S9

+S9

Solvent control

142

147

10

12

30

31

20

29

6

11

156.3

133

165

11

9

33

33

17

27

6

12

312.5

153

147

8

10

35

37

23

25

7

12

625

127

136

8

9

35

35

26

28

8

13

1250

141

166

13

13

33

34

20

35

6

13

2500

145

152

9

13

31

33

21

40

9

10

5000

137

155

12

8

29

36

19

38

7

14

Positive control

551

949

563

209

226

1019

519

502

496

236

Applicant's summary and conclusion

Conclusions:
1,1,1,3,5,5,5-heptamethyl-3-[(trimethylsilyl)oxy]trisiloxane has been tested for mutagenicity to bacteria, in a study which was conducted according to a Japanese guideline similar to OECD TG 471, not in compliance with GLP. No evidence of a test substance related increase in the number of revertants was observed with or without metabolic activation in the initial or the repeat experiment, both of which used the pre-incubation method. Appropriate 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.