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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:
2001-10-24 - 2001-11-28
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2002
Report Date:
2002

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
GLP compliance:
yes
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:
Aroclor 1254 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: DMSO
- Justification for choice of solvent/vehicle: Sponsor's request due to compatibility with the target cells. A fresh bottle, containing less that 0.1% water, to be opened and used once for each phase of the study.
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 10 µg/plate
Remarks:
WP2 uvrA with metabolic activation
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: 2-aminoanthracene 1.0 µg/plate
Remarks:
TA98, TA100, TA1535, TA1537 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:
TA100, 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:
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 glucose-6 phosphate and NADP as co-factors, and 10% S9. 0.5 ml of S9 was added to 2 ml top agar, 100 µl tester strain and 50 µl of test solution giving a final concentration of 1% S9.

DURATION

- Exposure duration: 48 - 72 hours at 37±2°C


SELECTION AGENT (mutation assays): histidine-deficient agar

NUMBER OF REPLICATIONS: triplicate plates, experiment repeated


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



Evaluation criteria:
The mean of each positive control must exhibit at least a 3 fold increase in the number of revertants over the mean value of the respective vehicle control. A minimum of three non-toxic dose levels is required to evaluate assay data. A dose level is considered toxic if one or both of the following criteria are met: (1) A >50% reduction in the mean number of revertants per plate as compared to the mean vehicle control value. This reduction must be accompanied by an abrupt dose-dependent drop in the revertant count. (2) A reduction in the background lawn. Data sets will be judged positive if the increase in mean revertants at the peak dose response is equal to or greater than 2 times the mean negative control value.
Statistics:
None shown in report

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

 Experiment 1 Plate incorporation - Number of revertants per plate (mean of three plates)

Treatment µg/plate

TA98

TA100

TA1535

TA1537

WP2 uvrA

-S9

+S9

-S9

+S9

-S9

+S9

-S9

+S9

-S9

+S9

0*

15

 18

154

181

 14

 12

  4

 7

11

 11

100

11

 21

170

161

 13

 10

  3

 5

10

  8

333

11

 16

155

196

   9

 13

  4

 6

 9

  6

1000

11

 17

140

178

 13

 11

  3

 5

 9

  8

3333

15

 18

166

152

 21

 8

  6

 4

10

 12

5000

20

 21

149

159

 20

 14

  5

 5

10

  8

Positive control

92

365

479

584

215

102

633

 58

71

296

*solvent control with DMSO

 Experiment 2 Plate incorporation - Number of revertants per plate (mean of three plates)

Treatment µg/plate

TA98

TA100

TA1535

TA1537

WP2 uvrA

-S9

+S9

-S9

+S9

-S9

+S9

-S9

+S9

-S9

+S9

0 *

16

 20

134

154

 19

 12

  8

   7

12

 12

100

10

 19

138

165

 21

 15

  5

 10

14

 13

333

15

 23

152

163

 17

 19

  5

 10

12

 17

1000

15

 28

137

181

 19

 14

 13

   9

12

 16

3333

15

 25

136

145

 21

 16

  9

  6

10

 14

5000

13

 22

124

151

 18

 16

  7

  4

10

 13

Positive control

67

495

441

690

203

124

352

137

84

291

 *solvent control with DMSO

Applicant's summary and conclusion

Conclusions:
Methylsilanetriyl triacetate has been tested for mutagenicity to bacteria in a study which was conducted according to the 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. Appropriate positive and solvent 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.