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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
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
The range of strains used does not comply with current guidelines

Data source

Referenceopen allclose all

Reference Type:
study report
Title:
Unnamed
Year:
1993
Report date:
1993
Reference Type:
publication
Title:
No information
Author:
Vergnes et al.
Year:
2000
Bibliographic source:
Environ. Molec. Mutagen. 36, 13-21

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Version / remarks:
1983
Qualifier:
according to guideline
Guideline:
other: EPA Fed Reg 50, 51, 51 (1987)
Principles of method if other than guideline:
preincubation method
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay

Test material

Constituent 1
Chemical structure
Reference substance name:
Octamethylcyclotetrasiloxane
EC Number:
209-136-7
EC Name:
Octamethylcyclotetrasiloxane
Cas Number:
556-67-2
Molecular formula:
C8H24O4Si4
IUPAC Name:
2,2,4,4,6,6,8,8-octamethyl-1,3,5,7,2,4,6,8-tetroxatetrasilocane

Method

Species / strain
Species / strain / cell type:
S. typhimurium, other: TA98, TA100, TA1535, TA1537, TA1538
Metabolic activation:
with and without
Metabolic activation system:
Aroclor 1254-induced rat liver S9 
Test concentrations with justification for top dose:
0.0003 - 5.0 mg/plate (10 concentrations, cytotoxicity test); 0.1-5.0 mg/plate (5 concentrations, mutagenicity test)
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: ethanol
Controlsopen allclose all
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: 4-nitro-phenylenediamine
Remarks:
TA 98 and TA 1538 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:
sodium azide
Remarks:
TA 100 and TA 1535 without 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:
METHOD OF APPLICATION: in agar (plate incorporation); preincubation;

DURATION
- Preincubation period: 20 minutes
- Exposure duration: 48-72 hours
- Expression time (cells in growth medium): 48-72 hours


NUMBER OF REPLICATIONS: triplicate


DETERMINATION OF CYTOTOXICITY
- Method: other: growth of background lawn, number of revertants

METABOLIC ACTIVATION
S9 homogenate from Aroclor 1254-induced rats was obtained from Microbiological associates, Bethesda, Maryland, and checked for activity with 7,12-dimethylbenzanthracene. S9 mix included 8 mM MgCl2, 33 mM KCl, 5 mM glucose-6-phophate, 4 mM NADP. 100 mM sodium phosphate pH 7.4, and S9. Amount of S9 was based on activity with 7,12-dimethylbenzanthracene.
Evaluation criteria:
A dose-related increase in the mean reversion frequency compared to solvent control in at least one strain was considered positive if at least one dose produced at least twice the reversion frequency of the solvent control
Statistics:
Mean an standard deviation of replicate plates

Results and discussion

Test results
Key result
Species / strain:
other: Salmonella typhimurium 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
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid

Any other information on results incl. tables

Concurrent sterility testing indicated that the test substance, the S9 mix, and all solvent and control agents were sterile.

Table 1a: Experiment 1 Plate incorporation Number of revertants per plate (mean of 3 plates)

Conc.
(µl/ml)

TA 98

TA 100

TA 1535

- MA

+ MA

Cytotoxic
(yes/no)

- MA

+ MA

Cytotoxic
(yes/no)

- MA

+ MA

Cytotoxic
(yes/no)

0*

18

27

No

108

112

No

15

18

No

100

20

34

No

105

131

No

17

20

No

300

17

30

No

127

109

No

16

15

No

1000

29

27

No

123

116

No

18

18

No

3000

24

27

No

117

109

No

16

18

No

5000

20

31

No

125

112

No

18

16

No

Positive control

431

1216

-

933

1780

-

1033

15

-

*solvent control with ethanol

 

 

Table 1b : Experiment 1 Plate incorporation Number of revertants per plate

 

Conc.
(µl/ml)

TA 1537

TA 1538

- MA

+ MA

Cytotoxic
(yes/no)

- MA

+ MA

Cytotoxic
(yes/no)

0*

13

6

No

9

17

No

100

9

12

No

8

16

No

300

9

7

No

12

24

No

1000

8

10

No

9

17

No

3000

7

9

No

6

20

No

5000

10

7

No

7

13

No

Positive control

118

169

-

924

1259

-

*solvent control with ethanol

 

Table 2a: Experiment 2 Plate incorporation Number of revertants per plate (mean of 3 plates)

Conc.
(µl/ml)

TA 98

TA 100

TA 1535

- MA

+ MA

Cytotoxic
(yes/no)

- MA

+ MA

Cytotoxic
(yes/no)

- MA

+ MA

Cytotoxic
(yes/no)

0*

21

31

No

126

117

No

12

15

No

100

21

23

No

119

111

No

11

14

No

300

22

32

No

110

122

No

16

19

No

1000

19

21

No

105

91

No

15

14

No

3000

22

22

No

123

97

No

9

11

No

5000

13

26

No

107

102

No

12

14

No

Positive control

680

1038

-

942

2249

-

942

153

-

*solvent control with ethanol

 

 

Table 2b : Experiment 2 Plate incorporation Number of revertants per plate

 

Conc.
(µl/ml)

TA 1537

TA 1538

- MA

+ MA

Cytotoxic
(yes/no)

- MA

+ MA

Cytotoxic
(yes/no)

0*

7

9

No

7

16

No

100

8

6

No

5

14

No

300

7

5

No

9

12

No

1000

9

6

No

9

16

No

3000

8

6

No

9

13

No

5000

8

8

No

8

16

No

Positive control

 282

337

-

715

1364

-

*solvent control with ethanol

Applicant's summary and conclusion

Conclusions:
Octamethylcyclotetrasiloxane has been tested under GLP according to OECD 471 (1983). No increase in the number of reversions was observed. The test substance is considered to be negative for mutagenicity in bacteria under the conditions of the test.