Registration Dossier

Administrative data

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Clioquinol was found to be non-genotoxic.

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:
weight of evidence
Reliability:
2 (reliable with restrictions)
Qualifier:
according to guideline
Guideline:
other:
Principles of method if other than guideline:
PREINCUBATION : In the standard protocol (preincubation) for conducting the Ames assay, a test tube containing a suspension of one strain of Salmonella typhimurium (or E. coli) plus S9 mix or plain buffer without S9, is incubated for 20 minutes at 37º C with the test chemical. Control cultures, with all the same ingredients except the test chemical, are also incubated. In addition, positive control cultures are prepared; these contain the particular bacterial tester strain under investigation, the various culture ingredients, and a known potent mutagen*. After 20 minutes, agar is added to the cultures and the contents of the tubes are thoroughly mixed and poured onto the surface of Petri dishes containing standard bacterial culture medium. The plates are incubated, and bacterial colonies that do not require an excess of supplemental histidine appear and grow. These colonies are comprised of bacteria that have undergone reverse mutation to restore function of the histidine-manufacturing gene. The number of colonies is usually counted after 2 days.
GLP compliance:
not specified
Type of assay:
bacterial reverse mutation assay
Species / strain / cell type:
S. typhimurium TA 100
Additional strain / cell type characteristics:
not specified
Species / strain / cell type:
S. typhimurium TA 1535
Additional strain / cell type characteristics:
not specified
Species / strain / cell type:
S. typhimurium TA 1537
Additional strain / cell type characteristics:
not specified
Species / strain / cell type:
S. typhimurium TA 97
Additional strain / cell type characteristics:
not specified
Species / strain / cell type:
S. typhimurium TA 98
Additional strain / cell type characteristics:
not specified
Metabolic activation:
with and without
Metabolic activation system:
with 10 % & 30 % HLI = induced male Syrian hamster liver S9 and 10% & 30 % RLI = induced male Sprague Dawley rat liver S9
Test concentrations with justification for top dose:
1-100 µg/Plate
Vehicle / solvent:
Dimethyl Sulfoxide
Untreated negative controls:
not specified
Negative solvent / vehicle controls:
yes
Remarks:
Dimethyl Sulfoxide
True negative controls:
not specified
Positive controls:
yes
Positive control substance:
other: 2-aminoanthracene
Remarks:
For strains tested with S9
Untreated negative controls:
not specified
Negative solvent / vehicle controls:
yes
Remarks:
Dimethyl Sulfoxide
True negative controls:
not specified
Positive controls:
yes
Positive control substance:
sodium azide
Remarks:
For strains TA100 and TA1535 tested in the absence of S9
Untreated negative controls:
not specified
Negative solvent / vehicle controls:
yes
Remarks:
Dimethyl Sulfoxide
True negative controls:
not specified
Positive controls:
yes
Positive control substance:
9-aminoacridine
Remarks:
For strain TA97 and TA1537 tested in the absence of S9
Untreated negative controls:
not specified
Negative solvent / vehicle controls:
yes
Remarks:
Dimethyl Sulfoxide
True negative controls:
not specified
Positive controls:
yes
Positive control substance:
2-nitrofluorene
Remarks:
For strain TA98 tested in the absence of S9
Details on test system and experimental conditions:
Test System : AMES SALMONELLA TYPHIMURIUM
Species / strain:
S. typhimurium TA 100
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
not specified
Vehicle controls validity:
not specified
Untreated negative controls validity:
not specified
Positive controls validity:
not specified
Species / strain:
S. typhimurium TA 1535
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
not specified
Vehicle controls validity:
not specified
Untreated negative controls validity:
not specified
Positive controls validity:
not specified
Species / strain:
S. typhimurium TA 1537
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
not specified
Vehicle controls validity:
not specified
Untreated negative controls validity:
not specified
Positive controls validity:
not specified
Species / strain:
S. typhimurium TA 97
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
not specified
Vehicle controls validity:
not specified
Untreated negative controls validity:
not specified
Positive controls validity:
not specified
Species / strain:
S. typhimurium TA 98
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
not specified
Vehicle controls validity:
not specified
Untreated negative controls validity:
not specified
Positive controls validity:
not specified
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.

Strain: TA100

Dose

No Activation 
(Negative)

No Activation 
(Negative)

10% HLI 
(Negative)

30% HLI 
(Negative)

10% RLI 
(Negative)

30% RLI 
(Negative)

Protocol

Preincubation

Preincubation

Preincubation

Preincubation

Preincubation

Preincubation

ug/Plate

Mean

± SEM

Mean

± SEM

Mean

± SEM

Mean

± SEM

Mean

± SEM

Mean

± SEM

0     

153

18.5

136

3.8

134

4.2

174

3.4

140

11.2

168

4.2

 0.03  

149

10.7

142

4.6

 

 

 

 

 

 

 

 

 0.1   

139

13.3

142

10.4

 

 

 

 

 

 

 

 

 0.3   

147

4.4

129

11.5

 

 

 

 

144

11.9

165

9.2

1     

136

2.6

82

1.8

152

7.1

158

1.9

129

3.5

153

9.4

1.6   

120

8.5

 

 

 

 

 

 

 

 

 

 

3     

 

 

0s

0

147

3.9

181

12.9

126

7.2

155

6.9

10     

 

 

 

 

146

3.7

153

21.3

96

3.7

142

8.4

16     

 

 

 

 

 

 

 

 

 

 

118

7.8

33     

 

 

 

 

103

8.7

184

3.6

13

5.1

 

 

66     

 

 

 

 

 

 

172

8.6

 

 

 

 

100     

 

 

 

 

0s

0

 

 

 

 

 

 

Positive Control

439

15.8

412

8.4

835

37.2

545

10.8

602

17.8

842

33.8

 Strain: TA1535

Dose

No Activation 
(Negative)

No Activation 
(Negative)

10% HLI 
(Negative)

30% HLI 
(Negative)

10% RLI 
(Negative)

30% RLI 
(Negative)

Protocol

Preincubation

Preincubation

Preincubation

Preincubation

Preincubation

Preincubation

ug/Plate

Mean

± SEM

Mean

± SEM

Mean

± SEM

Mean

± SEM

Mean

± SEM

Mean

± SEM

0     

24

2.2

39

1.5

18

1.8

9

2.3

18

3.4

19

2.6

 0.03  

33

2.3

28

2.6

 

 

 

 

 

 

 

 

 0.1   

22

1.2

31

1.9

 

 

 

 

 

 

 

 

 0.3   

24

2.7

31

3.2

 

 

 

 

16

2

20

1.9

1     

26

1.2

31

3

18

0.9

12

1

16

0.7

17

0.3

1.6   

29

4.6

 

 

 

 

 

 

 

 

 

 

3     

 

 

7

0.6

18

6.8

9

2.4

18

2.5

20

2.6

10     

 

 

 

 

17

0.3

10

1.9

11

2.4

13

2.1

16     

 

 

 

 

 

 

 

 

 

 

20

2.3

33     

 

 

 

 

14

2.6

8

0.3

6

1.3

 

 

66     

 

 

 

 

 

 

15

1.5

 

 

 

 

100     

 

 

 

 

11

3.8

 

 

 

 

 

 

Positive Control

370

9.4

418

49.7

201

6.9

403

13.1

110

7.3

96

2.6

S

Conclusions:
Interpretation of results (migrated information):
negative

In an Ames test , clioquinol , in dimethyl sulfoxide from doses 1-100 µg/Plate was not mutagenic in Salmonella typhimurium strains TA100,TA1535,TA1537,TA97 and TA98 with and without addition of S9 liver fractions from Aroclor induced hamsters. The same has been observed for rats as well.
Executive summary:

In an Ames test , clioquinol , in dimethyl sulfoxide from doses 1-100 µg/Plate was not mutagenic in Salmonella typhimurium strains TA100,TA1535,TA1537,TA97 and TA98 with and without addition of S9 liver fractions from Aroclor induced hamsters. The same has been observed for rats as well.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (negative)

Additional information

Additional information from genetic toxicity in vitro:

Weight of evidence studies reviewed for Genetic toxicity from reliable sources having Klimish rating 2.

 

The summary of the results are presented below

 

Sr.No

Endpoint

Interpretation of results

Strain/Species

Sources

1

Gene Mutation

Negative with and without metabolic activation

S. typhimurium TA 100,TA 1535,TA 1537,TA 97,TA 98

Environ. Molec. Mutagen.

2

Chromosomal abberation

Negative without metabolic activation

Chinese hamster Lung (CHL)

SSS QSAR

3

Gene mutation

Negative without metabolic activation

S. typhimurium TA 100

SSS QSAR

 

By applying weight of evidence approach, it was concluded that the test substance clioquinol does not exhibit positive gene mutation effect as is the same case for chromosome abberation.

Justification for selection of genetic toxicity endpoint

In an Ames test , clioquinol , in dimethyl sulfoxide from doses 1-100 µg/Plate was not mutagenic in Salmonella typhimurium strains TA100,TA1535,TA1537,TA97 and TA98  with and without addition of S9 liver fractions from Aroclor induced hamsters. The same has been observed for rats as well.The chromosome abberation is based on the prediction for in-vitro mammalian chromosome aberration test on Chinese hamster Lung (CHL) without S9 metabolic activation it was estimated that clioquinol does not exhibit positive chromosomal effect.

Justification for classification or non-classification

Clioquinol shows negative activity as is the case for chromosome abberation for the same substance.