Registration Dossier

Administrative data

Endpoint:
in vitro gene mutation study in bacteria
Remarks:
Type of genotoxicity: gene mutation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Feb 2000
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2000
Report Date:
2000

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method B.13/14 (Mutagenicity - Reverse Mutation Test Using Bacteria)
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 870.5100 - Bacterial Reverse Mutation Test (August 1998)
Deviations:
no
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent

Method

Target gene:
Histidine gene locus
Species / strain
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102
Additional strain / cell type characteristics:
not applicable
Metabolic activation:
with and without
Metabolic activation system:
Aroclor 1254 induced male rat liver S9 mix
Test concentrations with justification for top dose:
0, 50, 158, 500, 1581, 5000 µg/plate (first and repeat test)








Vehicle / solvent:
DMSO
Controls
Untreated negative controls:
yes
Negative solvent / vehicle controls:
no
Remarks:
No solvent control was used since sufficient evidence was available in the literature and from testing laboratory experience, indicating that the solvents used had no influence on the spontaneous mutant counts of the used strains.
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: sodium azide (only TA 1535), nitrofurantoin (only TA 100), 4-nitro-1,2-phenylene diamine (TA 1537 and TA 98), cumene hydroperoxide (only TA 102), 2-aminoanthracene.
Remarks:
The positive controls sodium azide, nitrofurantoin, 4-nitro-1,2-phenylene diamine and cumene hydroperoxide were only used without S9 mix; the positive control 2-aminoanthracene was only used with S9 mix.
Details on test system and experimental conditions:
METHOD: Standard plate test and preincubation test; each concentration including the controls was tested in triplicate.
Evaluation criteria:
A reproducible and dose-related increase in mutant counts of at least one strain is considered to be a positive result. For TA 1535, TA 1537, TA 100 and TA 98 this increase should be about twice that of negative controls. For TA 102 an increase of about 100 mutants should be reached. Otherwise, the result is evaluated as negative. However, these criteria may be overruled by good scientific judgment. In case of questionable results, investigations should continue, possibly with modifications, until a final evaluation is possible.
Statistics:
not specified

Results and discussion

Test results
Species / strain:
S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
not examined
Positive controls validity:
valid
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.

Any other information on results incl. tables

Table 1: Summary of results from the Salmonella mutagenicity assay (first test) with Bay 38-7268 (mean values of revertants per plate)

 Dose (µg per plate)

Without metabolic activation

 

 TA 1535

 TA 100

 TA 1537

 TA 98

 TA 102

0

10

60

6

22

175

50

7

60

6

18

193

158

8

51

5

19

188

500

6

53

6

17

178

1581

10

48

8

19

175

5000

6

44

7

13

173

 Positive control

487

174

104

171

275 

 Dose (µg per plate )

With metabolic activation (liver S9 mix)

 

 TA 1535

 TA 100

 TA 1537

 TA 98

TA 102

0

10

81

7

25

261

50

10

75

7

24

251

158

5

67 

8

26

262

500

7

73

7

31

225

1581

9

77

8

30

245

5000

9

72

7

30

221

 Positive control

212

996

177

1462

661

Table 2: Summary of results from the Salmonella mutagenicity assay (repeat test) with Bay 38-7268 (mean values of revertants per plate)

 Dose (µg per plate)

Without metabolic activation

 

 TA 1535

 TA 100

 TA 1537

 TA 98

 TA 102

0

6

71

9

15

187

50

8

70

8

16

233

158

8

57

7

16

207

500

7

60

5

16

166

1581

5

54

3

15

192

5000

5

50

4

14

129

 Positive control

631

247

142

147

473 

 Dose (µg per plate )

With metabolic activation (liver S9 mix)

 

 TA 1535

 TA 100

 TA 1537

 TA 98

TA 102

0

8

79

10

25

303

50

9

93

9

30

350

158

9

91 

11

28

325

500

5

94

9

36

257

1581

7

89

4

21

263

5000

8

74

4

17

227

 Positive control

210

1203

276

1385

484

Doses up to and including 5000 µg per plate did not cause any bacteriotoxic effects. Total bacteria counts remained unchanged and no inhibition of growth was observed. Substance precipitation occurred at the dose 1581 µg per plate and above.

Evidence of mutagenic activity of Bay 38-7268 was not seen. No biologically relevant increase in the mutant count, in comparison with the negative controls, was observed.

The positive controls sodium azide, nitrofurantoin, 4-nitro-1,2-phenylene diamine, cumene hydroperoxide and 2-aminoanthracene had a marked mutagenic effect, as was seen by a biologically relevant increase in mutant colonies compared to the corresponding negative controls.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
negative
Executive summary:

The mutagenic potential of Bay 38-7268 was evaluated in a Salmonella/microsome test with the S. typhimurium strains TA 98, TA 100, TA 102, TA 1535 and TA 1537 in the presence and absence of S9 mix according to OECD TG 471. Evidence of mutagenic activity was not seen up to the maximum recommended dose level of 5000 µg/plate. No biologically relevant increase in the mutant count, in comparison with the negative controls, was observed. Substance precipitation occurred at the dose 1581 µg per plate and above. Based on this test, the test substance was considered to be non-mutagenic without and with S9 mix in the plate incorporation as well as in the preincubation modification of the Salmonella/microsome test.