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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:
1987-06-03 to 1987-07-10
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1987
Report Date:
1987

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Principles of method if other than guideline:
other: Ames et al. 1973
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent

Method

Species / strain
Species / strain / cell type:
other: Salmonella typhimurium: TA 98, TA 100, TA 1535, TA1537, TA1538 and Escherichia coli WP2uvrA
Metabolic activation:
with and without
Metabolic activation system:
Aroclor induced rat liver S9
Test concentrations with justification for top dose:
See table 1.
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: acetone
Controlsopen allclose all
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
sodium azide
Remarks:
TA 100, TA 1535 (without 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 activation)
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
2-nitrofluorene
Remarks:
TA 98, TA 1538 (without activation)
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: N-Methyl-N-nitro-N-nitrosoguanidine
Remarks:
WP2uvrA (without activation)
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
benzo(a)pyrene
Remarks:
All strains (with activation)
Untreated negative controls:
no
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: Male Sprague Dawley rats (200-300g) were dosed with 500 mg/ kg bw Aroclor 1254 5 d before sacrifice. Livers from 5-6 animals were polled and used to prepare S9 homogenate. S9 mix included 10% v/v S9, 8 mM MgCl2, 33 mM KCl, 5mM glucose-6-phosphate, 4 mM NADP+ and 100 mM phosphate buffer pH 7.4. 0.5 ml of S9 mix were added to 2 ml top agar, 0.1 ml bacterial culture and 0.1 ml test substance solution (total volume 2.7 ml) giving a final concentration of S9 of approximately 2%.

METHOD OF APPLICATION: in agar (plate incorporation)


DURATION
- Exposure duration:

SELECTION AGENT (mutation assays):
SPINDLE INHIBITOR (cytogenetic assays):
STAIN (for cytogenetic assays): 48-72 hours

NUMBER OF REPLICATIONS: 3 plates per test concentration. The experiment was repeated.

DETERMINATION OF CYTOTOXICITY

- Method: other: Background lawn assessment
Evaluation criteria:
Mutagenicity of the test substance is indicated by an increase in the number of revertant colonies.
Statistics:
Statistical methods: Responses (numbers of revertants) to the test substance were compared to concurrent negative and positive 
controls, as well as to historical data.

Results and discussion

Test results
Species / strain:
other: Salmonella typhimurium: TA 98, TA 100, TA 1535, TA1537, TA1538 and Escherichia coli WP2uvrA
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
other: >1500 µg/plate
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid
Additional information on results:
The test compound was toxic to most of the bacterial strains and precipitate was observed at doses greater than or equal to 2500 ug/plate, both with and without metabolic activation.  Final mutagenicity testing was conducted with 5000 ug/plate as the top dose.  The results of the tests conducted on the test substance in the absence or presence of a metabolic activation system were all negative.
Revertants per plate for positive control substances ranged from 18- 680, depending on the agent and strain.

Any other information on results incl. tables

 

Table 2 : Exp 1 : Mutagenicity assay for all strains with and without metabolic activation (mean of 3 plates)

 

TA98

TA100

TA1535

Conc.
(
µg/plate)

— MA

+ MA

Cytotoxic
(yes/no)

— MA

+ MA

Cytotoxic
(yes/no)

— MA

+ MA

Cytotoxic
(yes/no)

0*

25

30

No

158

175

No

13

12

No

4

21

29

No

153

159

No

12

11

No

20

19

28

No

148

174

No

11

12

No

100

23

28

No

152

181

No

12

10

No

500

27

24

No

148

187

No

14

12

No

2500

18

23

No

166

174

No

8

14

No

10,000

-

3

Yes

-

-

Yes

6

2

Yes

Positive Control

364

437

No

554

611

No

404

119

No

*solvent control with Acetone

 

Table 2 : Exp 1 : Mutagenicity assay for all strains with and without metabolic activation (mean of 3 plates)

 

TA1537

TA1538

WP2uvrA

Conc.
(
µg/plate)

— MA

+ MA

Cytotoxic
(yes/no)

— MA

+ MA

Cytotoxic
(yes/no)

— MA

+ MA

Cytotoxic
(yes/no)

0*

12

8

No

17

17

No

47

52

No

4

9

8

No

16

20

No

43

51

No

20

7

8

No

13

20

No

44

53

No

100

7

9

No

16

22

No

40

48

No

500

8

5

No

16

24

No

46

57

No

2500

8

6

No

16

11

No

43

41

No

10,000

-

0

Yes

4

1

Yes

-

12

Yes

Positive Control

155

84

No

591

547

No

241

174

No

*solvent control with Acetone

 

Table 3 : Exp 2 : Repeat Assay Number of revertants per plate (mean of 3 plates)

 

TA98

TA100

TA1535

Conc.
(
µg/plate)

— MA

+ MA

Cytotoxic
(yes/no)

— MA

+ MA

Cytotoxic
(yes/no)

— MA

+ MA

Cytotoxic
(yes/no)

0*

19

32

No

168

205

No

16

13

No

4

27

40

No

153

234

No

17

13

No

20

23

36

No

180

2335

No

17

13

No

100

26

35

No

182

197

No

15

12

No

500

24

27

No

141

207

No

11

16

No

2500

24

29

No

183

207

No

16

16

No

5000

-

25

Yes

119

167

No

13

16

No

Positive control

249

377

No

483

628

No

308

76

No

*solvent control with Acetone

 

Table 3 : Exp 2 : Repeat Assay Number of revertants per plate (mean of 3 plates)

 

TA1537

TA1538

WP2uvrA

Conc.
(
µg/plate)

— MA

+ MA

Cytotoxic
(yes/no)

— MA

+ MA

Cytotoxic
(yes/no)

— MA

+ MA

Cytotoxic
(yes/no)

0*

12

9

No

14

23

No

48

75

No

4

8

9

No

13

26

No

61

68

No

20

9

8

No

13

26

No

59

58

No

100

9

7

No

15

20

No

63

52

No

500

8

7

No

12

23

No

50

35

No

2500

9

10

No

16

19

No

39

37

No

5000

4

6

Yes

14

18

No

23

26

Yes

Positive control

94

91

No

458

515

No

365

304

No

*solvent control with Acetone

 

 

Applicant's summary and conclusion

Conclusions:
Dichlorodimethylsilane has been tested for mutagenicity to bacteria according to a protocol similar to the current guideline. The test substance did not demonstrate genetic activity in any of Salmonella typhimurium strains TA 98, TA 100, TA 1535, TA1537, TA1538 and Escherichia coli WP2uvrA, up to cytotoxic concentration, with or without metabolic activation. Appropriate positive and solvent controls were included and gave expected results. It is concluded that the test substance is not mutagenic to bacteria under the conditions of the test.