Registration Dossier

Administrative data

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information
Salmonella/microsome test (Ames test): weakly positive with strain TA 1537 (+ S9 mix) and negative with strains TA 98, TA 100, TA 102 and TA 1535 (+/- S9 mix)
Link to relevant study records
Reference
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 to March 2000
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study
Reference:
Composition 0
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 information:
Composition 1
Target gene:
Histidine gene locus
Species / strain:
S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102
Additional strain 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, +/-S9 mix, all strains)
0, 1000, 2000, 3000, 4000, 5000, 6000, 7000 µg/plate (repeat test, +S9 mix, TA 1537 only)







Vehicle:
DMSO
Negative controls:
yes
Solvent 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 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
Species / strain:
other: TA 1537
Metabolic activation:
with
Genotoxicity:
positive
Cytotoxicity:
yes
Remarks:
weak, strain-specific bacteriotoxic effect at 7000 µg/plate
Vehicle controls valid:
not examined
Negative controls valid:
yes
Positive controls valid:
yes
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.
Species / strain:
other: TA 1537
Metabolic activation:
without
Genotoxicity:
negative
Cytotoxicity:
yes
Remarks:
weak, strain-specific bacteriotoxic effect at 7000 µg/plate
Vehicle controls valid:
not examined
Negative controls valid:
yes
Positive controls valid:
yes
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.
Species / strain:
other: TA 1535, TA 98, TA 100, TA 102
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity:
no
Remarks:
no bacteriotoxic effect up to 5000 µg/plate
Vehicle controls valid:
not examined
Negative controls valid:
yes
Positive controls valid:
yes
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.

Table 1: Summary of results from the Salmonella mutagenicity assay (first test) with Imidoxim (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

85

8

31

289

50

10

91

6

40

282

158

8

82

5

39

260

500

10

90

5

32

316

1581

13

71

9

33

303

5000

11

82

11

33

254

 Positive control

836

202

98

159

409 

 Dose ( µg per plate )

With metabolic activation (liver S9 mix)

 

 TA 1535

 TA 100

 TA 1537

 TA 98

TA 102

0

12

97

10

41

309

50

10

89

7

43

346

158

10

102 

9

40

344

500

9

98

13

41

341

1581

11

106

13

47

354

5000

7

116

20

30

348

 Positive control

293

1489

356

1570

920

Table 2: Summary of results from the Salmonella mutagenicity assay (repeat test) with Imidoxim (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

63

9

18

230

50

8

65

8

20

237

158

12

64

8

19

241

500

11

64

10

22

249

1581

16

81

9

22

249

5000

13

79

14

15

193

 Positive control

734

288

145

148

533 

Dose (µg per plate)

With metabolic activation (liver S9 mix)

 

 TA 1535

 TA 100

 TA 1537

 TA 98

TA 102

0

9

76

9

31

319

50

9

100

9

30

332

158

10

 98 

11

28

317

500

8

98

15

32

337

1581

10

91

19

30

326

5000

9

101

25

28

254

 Positive control

259

1654

312

1734

659

 

 

 

 

 

 

0

 

 

9

 

 

1000

 

 

13

 

 

2000

 

 

16

 

 

3000

 

 

20

 

 

4000

 

 

28

 

 

5000

 

 

29

 

 

6000

 

 

28

 

 

7000

 

 

29

 

 

Positive control

 

 

235

 

 

Doses up to and including 6000 µg per plate did not cause any bacteriotoxic effects. Total bacteria counts remained unchanged and no inhibition of growth was observed. At 7000 µg per plate, the substance had only a weak, strain-specific bacteriotoxic effect. Due to the weakness of this effect this dose could nevertheless be used for assessment purposes.

Evidence of mutagenic activity of Imidoxim was seen. Under both test conditions, a weak but biologically relevant increase was found in the mutant count of Salmonella typhimurium TA 1537 as compared to the corresponding negative control. Positive response was found only with S9 mix. The lowest reproducible dose was 3000 µg per plate. The Salmonella/microsome test thus showed Imidoxim to have a mutagenic effect. Due to the high amounts of Imidoxim need for a positive response, the positive result may be also due to an impurity.

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.

Conclusions:
Interpretation of results (migrated information):
positive with metabolic activation
Executive summary:

The mutagenic potential of Imidoxim 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. Doses up to and including 6000 µg per plate did not cause any bacteriotoxic effects. Total bacteria counts remained unchanged and no inhibition of growth was observed. At 7000 µg per plate, the substance had only a weak, strain-specific bacteriotoxic effect. Due to the weakness of this effect this dose could nevertheless be used for assessment purposes.

Evidence of mutagenic activity of Imidoxim was seen. Under both test conditions, a weak but biologically relevant increase was found in the mutant count of Salmonella typhimurium TA 1537 as compared to the corresponding negative control. Positive response was found only with S9 mix. The lowest reproducible dose was 3000 µg per plate. The Salmonella/microsome test thus showed Imidoxim to have a mutagenic effect. Due to the high amounts of Imidoxim need for a positive response, the positive result may be also due to an impurity.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed (positive)

Genetic toxicity in vivo

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

The mutagenic potential of Imidoxim 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 (Herbold, 2000). Doses up to and including 6000 µg per plate did not cause any bacteriotoxic effects. Total bacteria counts remained unchanged and no inhibition of growth was observed. At 7000 µg per plate, the substance had only a weak, strain-specific bacteriotoxic effect. Due to the weakness of this effect this dose could nevertheless be used for assessment purposes. Evidence of mutagenic activity of Imidoxim was seen. Under both test conditions, a weak but biologically relevant increase was found in the mutant count of Salmonella typhimurium TA 1537 as compared to the corresponding negative control. Positive response was found only with S9 mix. The lowest reproducible dose was 3000 µg per plate. The Salmonella/microsome test thus showed Imidoxim to have a mutagenic effect. Due to the high amounts of Imidoxim need for a positive response, the positive result may be also due to an impurity.

Justification for classification or non-classification

Based on the study results a classification according to Directive 67/548/EEC or Regulation (EC) No. 1272/2008 (CLP) is not warranted.