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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:
weight of evidence
Study period:
2002-05-13 to 2002-09-19
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)
Remarks:
Freie und Hansestadt Hamburg Behörde für Arbeit Gesundheit und Soziales
Type of assay:
bacterial reverse mutation assay

Test material

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

Method

Target gene:
his operon
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 102
Metabolic activation:
with and without
Metabolic activation system:
Aroclor induced rat liver S9-mix
Test concentrations with justification for top dose:
Preliminary toxicity test:
- 0.316, 1, 3.16, 10, 31.6, 100, 316, 1000, 3160 and 5000 µg/plate (without metabolic activation)
Experiment I:
- 10, 31.6, 100, 316 and 1000 µg/plate (with and without metabolic activation)
Experiment II:
- 10, 31.6, 100, 316 and 1000 µg/plate (with and without metabolic activation)
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: ethylene glycol dimethylether
- Justification for choice of solvent/vehicle: The solvent was chosen because of its solubility properties and relative non toxicity to bacteria
Controls
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: -S9-mix: sodium azide, 10 µg/plate (TA 100, TA 1535); 2-nitro-fluorene, 10 µg/plate (TA 98); 9-AA, 100 µg/plate (TA 1537); MMS, 1300 µg/plate (TA 102); +S9-mix: 2-AA, 2 µg/plate (TA 98, TA 102, TA 1537); CPA, 1500 µg/plate (TA 100, TA 1535)
Details on test system and experimental conditions:
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 resultsopen allclose all
Species / strain:
S. typhimurium, other: TA 1535, TA 1537, TA 98, TA 100
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
experiment I:at 1000 µg/plate (all strains, with and without S9-mix); experiment II: at 1000 µg/plate (all strains, without S9-mix); at 316 µg/plate (TA 98, TA 1535. TA 1537, without S9-mix), =316 µg/plate (all strains, with S9-mix)
Vehicle controls validity:
valid
Untreated negative controls validity:
not examined
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 102
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
experiment I: at 1000 µg/plate (with and without S9-mix); experiment II: =316 µg/plate (with and without S9-mix)
Vehicle controls validity:
valid
Untreated negative controls validity:
not examined
Positive controls validity:
valid
Additional information on results:
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 (TA 100 - MA)

 

TA100

Conc.
(µg/plate)

Plate 1

Plate 2

Cytotoxic
(yes/no)

0*

139

146

No

0.316

153

136

No

1

145

156

No

3.16

159

150

No

10

168

144

No

31.6

140

157

No

100

140

145

No

316

149

155

No

1000

0

0

Yes

3160

0

0

Yes

5000

0

0

Yes

*solvent control with Ethylene glycol dimethylether

Table 3: Experiment 1 Plate incorporation 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*

36.7

39.3

No

129.3

144

No

278.3

293.3

No

10

34.7

36.3

No

145.7

140.7

No

271

293

No

31.6

33.7

37

No

133.3

145

No

275

282

No

100

36.3

40.7

No

138.7

124.3

No

279.3

288.3

No

316

40.7

40.7

No

140.3

128.7

No

281.3

286.3

No

1000

0

0

Yes

0

0

Yes

0

0

Yes

Positive control

839.3

837.7

No

1168.7

1164

No

1186

1261.3

No

*solvent control with Ethylene glycol dimethylether

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

 

TA1535

TA1537

Conc.
µg/plate

MA

+ MA

Cytotoxic
(yes/no)

MA

+

MA

Cytotoxic
(yes/no)

0*

15.3

12.7

No

5

6.3

No

10

14.7

11.7

No

4

4.7

No

31.6

14.3

11.7

No

4.3

4.3

No

100

14.7

14

No

2.7

5.7

No

316

14

13

No

5.7

5

No

1000

0

0

Yes

0

0

Yes

Positive control

538.7

558

No

545.3

549.7

No

*solvent control with Ethylene glycol dimethylether

Table 4: Experiment 2 Preincubation 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*

35.3

36.7

No

129

145

No

277.3

289

No

10

36.3

38

No

116.3

124

No

279.7

269.7

No

31.6

37.3

30

No

129.3

114.7

No

287.3

274

No

100

27.7

27.3

No

140.3

112.7

No

268

266.3

No

316

30

0

Yes

136.3

0

Yes

258.7

0

Yes

1000

0

0

Yes

0

0

Yes

0

0

Yes

Positive control

1041

1070

No

1286.3

1292.3

No

1302

1306

No

*solvent control with Ethylene glycol dimethylether

Table 4: Experiment 2 Preincubation Number of revertants per plate (mean of 3 plates)

 

TA1535

TA1537

Conc.
µg/plate

— MA

+ MA

Cytotoxic
(yes/no)

— MA

+ MA

Cytotoxic
(yes/no)

0*

14.3

13

No

4

3.3

No

10

13

11.3

No

3

3.3

No

31.6

11

12

No

2.7

3

No

100

14

13.7

No

3.3

3

No

316

13

0

Yes

2.7

0

Yes

1000

0

0

Yes

0

0

Yes

Positive control

486

489

No

490

495

No

*solvent control with Ethylene glycol dimethylether

Applicant's summary and conclusion

Conclusions:
Interpretation of results: negative

Dichloromethyloctylsilane has been tested for mutagenicity to Salmonella typhimurium strain TA98, TA 100, TA102, TA 1535 and TA 1537 according to OECD TG 471, under conditions of GLP. No increase in the number of revertant colonies was observed with or without metabolic activation in any of the strains used in either the initial plate incorporation assay or the subsequent pre-incubation test. The test substance is non-mutagenic in the test strains used.