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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:
1992-09-21 - 1992-11-23
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Remarks:
The restrictions are that the only positive control used with metabolic activation was 2-aminoanthracene.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1992
Report Date:
1992

Materials and methods

Test guidelineopen allclose all
Qualifier:
equivalent or similar to
Guideline:
other: US EPA Standards 40 CFR 792 and 340 CFR 160
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
yes
Remarks:
the only positive control used with metabolic activation was 2-aminoanthracene
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent

Method

Target gene:
Histidine operon (Salmonella) tryptophan operon (E. coli)
Species / strainopen allclose all
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Species / strain / cell type:
S. typhimurium TA 1538
Species / strain / cell type:
E. coli WP2 uvr A
Metabolic activation:
with and without
Metabolic activation system:
Aroclor induced rat liver S9
Test concentrations with justification for top dose:
100, 333, 1000, 3333 and 5000 µg/plate
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: Acetone
- Justification for choice of solvent/vehicle: the test article formed a solution 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-aminoanthracene, all TA strains at 1.0 µg/plate, WP2 uvrA at 10 µg/plate
Remarks:
TA98, TA100, TA1535, TA1537, TA1538, WP2 uvrA with metabolic activation
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
2-nitrofluorene
Remarks:
TA98 without metabolic activation 1.0 µg/plate
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
sodium azide
Remarks:
TA1535 without metabolic activation 1.0 µg/plate
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
9-aminoacridine
Remarks:
TA1537 without metabolic activation 75 µg/plate
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
2-nitrofluorene
Remarks:
TA1538 without metabolic activation 1.0 µg/plate
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
methylmethanesulfonate
Remarks:
WP2 uvrA without metabolic activation 1000 µg/plate
Details on test system and experimental conditions:
METHOD OF APPLICATION: in agar (plate incorporation)

ACTIVATION: S9 mix contained 10% S9 and glucose-6-phosphate and NADP as co-factors. 500 µl of S9 mix was added to 2 ml top agar giving a final concentration of approximately 2% S9.

DURATION

- Exposure duration: 48 hours at 37+/- 2ºC

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:
For the test article to be evaluated positive, it must cause a dose-related increase in the mean revertants per plate of at least one tester strain with a minimum of two increasing concentrations of test article. Data sets for strains TA1535, TA1537 and TA 1538 will be judged positive if the increase in mean revertants is equal to or greater than three times the mean vehicle control value. Data sets for strains TA98, TA100 and WP2 uvrA will be judged positive if the increase in mean revertants is equal to or greater than two times the mean vehicle control value.

Results and discussion

Test resultsopen allclose all
Key result
Species / strain:
S. typhimurium, other: TA98, TA100, TA1535, TA1537, TA1538
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity nor precipitates, but tested up to recommended limit concentrations
Remarks:
Precipitate but no appreciable toxicity was observed
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
Remarks:
Precipitate but no appreciable toxicity was observed
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid
Additional information on results:
TEST-SPECIFIC CONFOUNDING FACTORS

- Precipitation: occurred between 1000 and 5000 µg/plate, did not interfere with test.

RANGE-FINDING/SCREENING STUDIES:

COMPARISON WITH HISTORICAL CONTROL DATA: yes

ADDITIONAL INFORMATION ON CYTOTOXICITY: cytotoxicity was not evident at any concentration

Any other information on results incl. tables

Summary of results – Experiment I Revertants per plate (mean of 3 plates)

 

Dose µg/ml

+/- metabolic activation

Average revertants per plate

TA98

TA100

TA1535

TA1537

TA1538

WP2 uvrA

Solvent control

-

14

161

10

4

6

19

100

-

17

151

7

5

7

14

333

-

14

158

11

4

8

14

1000

-

15

164

10

4

8

13

3333

-

16

162

9

3

9

16

5000

-

16

158

8

6

6

15

Positive control

-

195

707

355

224

279

150

Solvent control

+

28

177

11

8

11

20

100

+

24

189

11

7

8

19

333

+

20

185

14

5

11

18

1000

+

21

186

8

8

14

18

3333

+

22

184

12

5

12

16

5000

+

26

174

10

7

13

11

Positive control

+

1948

1269

37

39

228

374

 

Summary of results – Experiment II

 

 

Dose µg/ml

+/- metabolic activation

Average revertants per plate

TA98

TA100

TA1535

TA1537

TA1538

WP2 uvrA

Solvent control

-

11

123

6

5

7

15

100

-

12

111

11

4

7

15

333

-

8

113

5

4

5

12

1000

-

14

120

7

4

6

10

3333

-

9

121

10

4

5

15

5000

-

15

151

12

5

8

10

Positive control

-

123

386

297

301

295

145

Solvent control

+

19

137

14

4

13

20

100

+

18

139

12

7

10

15

333

+

19

144

7

6

14

19

1000

+

23

139

11

6

14

14

3333

+

20

143

10

6

7

10

5000

+

22

150

13

9

14

15

Positive control

+

817

814

51

95

818

410

 

Applicant's summary and conclusion

Conclusions:
1,1,3,3-Tetramethyl-1,3-divinyldisiloxane has been tested for mutagenicity to bacteria in a reliable study which was conducted according to a protocol that is equivalent to OECD TG 471, and 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 experiments using Salmonella typhimurium strains TA 98, 100, 1535, 1537 and 1538, and E.coli WP2uvrA. It is concluded that the test substance is negative for mutagenicity to bacteria under the conditions of the test.