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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:
2008-09-09 - 2008-10-10
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2009
Report Date:
2009

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Version / remarks:
1997
GLP compliance:
yes (incl. certificate)
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
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/β-Naphtholflavone induced rat liver S9
Test concentrations with justification for top dose:
Experiment 1 - 3, 10, 33, 100, 333, 1000, 2500 and 5000 µg/plate Experiment 2 - 33, 100, 333, 1000, 2500 and 5000 µg/plate
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: THF
- Justification for choice of solvent/vehicle: As agreed with the sponsor THF was chosen for its solubility properties and its relative non-toxicity to the 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:
TA100, TA1535 without metabolic 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-NOPD
Remarks:
TA98 10 µg/plate, TA1537 50 µg/plate, without metabolic 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 metabolic activation 3 µL/plate
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: 2-aminoanthracene
Remarks:
TA1535, TA1537, TA98, TA100 - 2.5 µg/plate. WP2 uvrA - 10 µg/plate with metabolic activation
Details on test system and experimental conditions:
METHOD OF APPLICATION: in agar (plate incorporation); preincubation

ACTIVATION: S9 mix contained glucose-6-phospate and NADP as co-factors. S9 was 10% v/v in the cultures.
DURATION
- Preincubation period: 60 minutes at 37ºC
- Exposure duration: 48 - 72 hours at 37ºC

SELECTION AGENT (mutation assays): histidine deficient agar


NUMBER OF REPLICATIONS: triplicate plates, experiment repeated

DETERMINATION OF CYTOTOXICITY
- Method: other: condition of background lawn


OTHER:
Evaluation criteria:
A test item is considered as a mutagen if a biologically relevant increase in the mean number of revertants exceeding the threshold twice (strains TA98, TA100 and WP2 uvrA) or thrice (strains TA1535 and TA1537) the mean colony count of the corresponding solvent control is observed. 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 second experiment.
Statistics:
No statistical evaluation of the data required.

Results and discussion

Test resultsopen allclose all
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:
valid
Positive controls validity:
valid
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:
valid
Positive controls validity:
valid
Additional information on results:
TEST-SPECIFIC CONFOUNDING FACTORS
- Precipitation: none observed


ADDITIONAL INFORMATION ON CYTOTOXICITY: none observed

Any other information on results incl. tables

Summary results – Experiment I

Dose µg/plate

+/- metabolic activation

Average number of colony counts

TA1535

TA1537

TA98

TA100

WP2 uvrA

Solvent control

-

11

7

27

123

44

Untreated control

-

9

9

23

119

44

3

-

15

8

28

116

40

10

-

13

11

25

111

44

33

-

13

9

31

128

51

100

-

14

13

35

115

48

333

-

8

8

19

101

40

1000

-

10

9

23

101

47

2500

-

16

12

25

108

50

5000

-

11

9

26

118

52

Positive control

-

1791

97

343

2013

1158

Solvent control

+

22

13

33

130

60

Untreated control

+

16

15

29

111

61

3

+

14

15

33

113

48

10

+

16

15

34

144

58

33

+

17

7

39

139

67

100

+

17

15

40

149

61

333

+

15

15

39

120

61

1000

+

15

13

38

138

56

2500

+

21

13

33

145

67

5000

+

17

12

39

145

65

Positive control

+

242

213

1452

1629

243

 

Summary results of Experiment II

Dose µg/plate

+/- metabolic activation

Average number of colony counts

TA1535

TA1537

TA98

TA100

WP2 uvrA

Solvent control

-

15

13

32

142

49

Untreated control

-

17

19

30

166

40

33

-

18

12

28

144

54

100

-

14

12

37

123

52

333

-

15

10

27

139

46

1000

-

14

10

28

141

48

2500

-

14

11

32

146

47

5000

-

14

13

28

141

47

Positive control

-

2076

120

523

2172

275

Solvent control

+

19

13

32

156

63

Untreated control

+

18

13

35

160

59

33

+

18

13

34

156

59

100

+

15

14

31

157

69

333

+

22

13

32

162

65

1000

+

17

13

36

159

67

2500

+

19

10

36

161

58

5000

+

21

10

32

153

48

Positive control

+

302

210

1986

2372

266

Applicant's summary and conclusion

Conclusions:
1,1,3,3-Tetramethyldisiloxane has been tested for mutagenicity to bacteria, in a study which was conducted according to OECD Test Guideline 471, in compliance with GLP. No evidence of a test substance related increase in the number of revertants was observed with or without activation in Salmonella typhimurium strains TA 98, TA 100, TA 1535 and TA 1537 and E.coli WP2uvrA in the initial or the repeat experiments. 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.