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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:
2002-05-10 to 2002-09-02
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)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: liquid

Method

Species / strain
Species / strain:
S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102
Metabolic activation:
with and without
Metabolic activation system:
Aroclor induced rat liver S9
Test concentrations with justification for top dose:
Pre-test: 0.316, 1, 3.16, 10, 31.6, 100, 316, 1000, 3160, 5000
Plate incorporation: 10, 31.6, 100, 316, 1000 µg/plate, with and without metabolic activation
Preincubation: 100, 316, 1000, 3160, 5000 µg/plate, with and without metabolic activation
Vehicle:
- Vehicle(s)/solvent(s) used: DMSO

- Justification for choice of solvent/vehicle: The solvent was chosen because of its solubility properties and its relative nontoxicity to the bacteria
Controlsopen allclose all
Negative controls:
no
Solvent controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
sodium azide
Remarks:
TA 1535, TA 100 (without activation)
Negative controls:
no
Solvent controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
2-nitrofluorene
Remarks:
TA 98 (without activation)
Negative controls:
no
Solvent controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
9-aminoacridine
Remarks:
TA 1537 (without activation)
Negative controls:
no
Solvent controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
methylmethanesulfonate
Remarks:
TA 102 (without activation)
Negative controls:
no
Solvent controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: 2-anthracene amide
Remarks:
TA 98, TA 102, TA 1537 (with activation)
Negative controls:
no
Solvent controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
cyclophosphamide
Remarks:
TA 100, TA 1535 (with activation)
Details on test system and conditions:
ACTIVATION: The protein content of the S9 fraction was 32.92 mg/mL S9. S9 mix was freshly prepared on the day of the test containing 5 % S9 and the following components (per 100 mL): 5.0 mL rat liver S9, 2.0 mL 0.4 M MgCl2 + 1.65 M KCl, 141.0 mg glucose-6-phosphate, 306.5 mg NADP, 50.0 mL 0.2 M phosphate buffer, pH 7.4.

METHOD OF APPLICATION: in agar (plate incorporation); preincubation

DURATION

- Preincubation period: 60 minutes

- Expression time (cells in growth medium): 48 hours

NUMBER OF REPLICATIONS: 3 plates for each test concentration

DETERMINATION OF CYTOTOXICITY
- Method: relative total growth; background lawn assessment
Evaluation criteria:
A result is positive if the number of revertants is significantly increased compared with the solvent control to at least 2-fold of the solvent control for TA 98, TA 100 and TA 102 and 3-fold of the solvent control for TA 1535 and TA 1537 in both experiments.

Positive results have to be reproducible and the histidine independence of the revertants has to be confirmed by streaking on histidine-free agar plates.

Cytotoxicity is defined as a reduction in the number of colonies by >50% compared with the solvent control and/or a sparse background lawn.

Statistics:
MANN and WHITNEY and Spearman’s rank.

Results and discussion

Test results
Species / strain:
S. typhimurium TA 1537
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity:
no, but tested up to limit concentrations
Vehicle controls valid:
yes
Negative controls valid:
not applicable
Positive controls valid:
yes
Remarks on result:
other: all strains/cell types tested
Additional information on results:
TEST-SPECIFIC CONFOUNDING FACTORS

- Precipitation: precipitation noted at 3160 - 5000 µg/plate

COMPARISON WITH HISTORICAL CONTROL DATA: Results were within range of historical control data


Any other information on results incl. tables

Table 2: Dose range-finding study Number of revertants per plate (2 plates - MA)

TA 100

Concentration (µg/Plate)

Plate 1

Plate 2

Cytotoxic (Yes/No)

0

143

146

No

0.316

154

138

No

1

188

140

No

3.16

171

144

No

10

161

162

No

31.6

144

145

No

100

145

138

No

316

115

130

No

1000

156

135

No

3160

195

154

No

5000

171

146

No

*solvent control with DMSO

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

 

TA98

TA100

TA102

Conc.
(
µg/plate)

— MA

+ MA

Cytotoxic
(yes/no)

MA

+ MA

Cytotoxic
(yes/no)

MA

+ MA

Cytotoxic
(yes/no)

0*

32

36

No

131

137.3

No

298

279.7

No

10

39.3

43

No

130.7

133.3

No

272

280.3

No

31.6

38.3

39.3

No

122

136.7

No

258.3

260.7

No

100

34.3

31.3

No

131

123.7

No

265.3

283.3

No

316

27.7

36.7

No

113

131

No

276

284.3

No

1000

23.3

24.7

No

120

132.3

No

293.7

285.3

No

Positive control

1255

1295.7

No

1194

1169

No

1130.7

1289

No

*solvent control with DMSO

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

 

TA1535

TA 1537

Conc.
(
µg/plate)

— MA

+ MA

Cytotoxic
(yes/no)

— MA

+ MA

Cytotoxic
(yes/no)

0*

13.7

13.7

No

5.3

6

No

10

12.7

13.7

No

4

5.3

No

31.6

13

13

No

3.7

7.3

No

100

14.3

13.3

No

3

7

No

316

13

12

No

5.3

6

No

1000

12.7

14

No

5

5

No

Positive control

564.3

563

No

570.7

566.7

No

*solvent control with DMSO

Table 4: Experiment 2 Pre incubation test Number of revertants per plate (mean of 3 plates)

 

TA98

TA100

TA102

Conc.
(
µg/plate)

— MA

+ MA

Cytotoxic
(yes/no)

MA

+ MA

Cytotoxic
(yes/no)

MA

+ MA

Cytotoxic
(yes/no)

0*

31

34.7

No

144.7

160.7

No

286.3

280

No

100

37.3

36.7

No

128.3

135

No

288

281

No

316

35

33.3

No

155.7

164.3

No

257.3

261.7

No

1000

31.3

27.3

No

150.7

155

No

271.3

267.7

No

3160

30.3

37.3

No

145.3

127

No

270.3

268.7

No

5000

30.7

33

No

131

129

No

282.7

264.3

No

Positive control

1033.7

1141

No

1186.7

1139.7

No

1163.3

1103.7

No

*solvent control with DMSO

Table 3: Experiment 2 Pre incubation test Number of revertants per plate (mean of 3 plates)

 

TA1535

TA 1537

Conc.
(
µg/plate)

— MA

+ MA

Cytotoxic
(yes/no)

— MA

+ MA

Cytotoxic
(yes/no)

0*

15

14

No

5.7

5.7

No

100

13.7

13.7

No

3.7

5

No

316

13

13.7

No

4.7

6

No

1000

14.3

13

No

5

5.7

No

3160

15.7

12.7

No

5.7

5.7

No

5000

14

13

No

4.7

5

No

Positive control

554.3

548

No

553.3

550

No

*solvent control with DMSO

Applicant's summary and conclusion

Conclusions:
1,3,5-trimethyl-1,1,3,5,5-pentaphenyltrisiloxane was tested for mutagenicity to bacteria in a study conducted according to OECD TG 471, and in compliance with GLP. No evidence of test-substance related increase in the number of revertants was observed with or without metabolic activation in S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102 in the initial plate incorporation experiment or the repeat assay using the preincubation method up to limit concentrations. Appropriate positive and solven controls were included and gave the expected results. It is concluded that the test substance is negative for mutagenicity to bacteria under the conditions of the test.