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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:
2017-10-24 till 2017-11-08
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018
Report date:
2018

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
no
Guideline:
other: The Japanese Ministry of Economy Trade and Industry (METI), Ministry of Health, Labour and Welfare (MHLW) and Ministry of the Environment (MOE) Guidelines of 31 March 2011
GLP compliance:
yes (incl. QA statement)
Type of assay:
bacterial reverse mutation assay

Test material

Constituent 1
Chemical structure
Reference substance name:
Titanium zirconium oxide
Molecular formula:
TixZryOz (x = 0.985 - 0.995, y = 1-x, z = 1.65 - 1.75)
IUPAC Name:
Titanium zirconium oxide
Test material form:
solid: bulk

Method

Species / strain
Species / strain / cell type:
other: TA 1535, TA 1537, TA 98, TA 100, and WP2 uvrA
Additional strain / cell type characteristics:
not applicable
Metabolic activation:
with and without
Metabolic activation system:
Phenobarbital/Beta-naphthoflavone induced rat liver S9
Test concentrations with justification for top dose:
Pre-Experiment/Experiment I: 3; 10; 33; 100; 333; 1000; 2500; and 5000 µg/plate
Experiment II: 33; 100; 333; 1000; 2500; and 5000 µg/plate
The dose selection was not adjusted to purity. Highest recommended dose according to OECD Guideline 471.
Vehicle / solvent:
Solvent used: deionized water
Justification for choice of solvent: best suitable solvent, because of its solubility properties and its relative nontoxicity to the bacteria
Controls
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
sodium azide
methylmethanesulfonate
other: 4-nitro-o-phenylene-diamine, 2-aminoanthracene
Details on test system and experimental conditions:
METHOD OF APPLICATION: in agar plate incorporation; pre-incubation

DURATION:
- Preincubation period: 60 Minutes
- Exposure duration: 48 hours

NUMBER OF REPLICATIONS: 3 plates for each concentration including the controls

DETERMINATION OF CYTOTOXICITY: Evident as a reduction in the number of spontaneous revertants (below the induction factor of 0.5) or a clearing of the bacterial background lawn.
Evaluation criteria:
A test item is considered as a mutagen if a biologically relevant increase in the number of revertants exceeding the threshold of twice (strains TA 98, TA 100, and WP2 uvrA) or thrice (strains TA 1535 and TA 1537) the colony count of the corresponding solvent control is observed.
A dose dependent increase is considered biologically relevant if the threshold is exceeded at more than one concentration.
An increase exceeding the threshold at only one concentration is judged as biologically relevant if reproduced in an independent second experiment.
A dose dependent increase in the number of revertant colonies below the threshold is regarded as an indication of a mutagenic potential if reproduced in an independent second experiment. However, whenever the colony counts remain within the historical range of negative and solvent controls such an increase is not considered biologically relevant.
Statistics:
According to the OECD guideline 471, a statistical analysis of the data is not mandatory.

Results and discussion

Test resultsopen allclose all
Key result
Species / strain:
S. typhimurium TA 1535
Metabolic activation:
with
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
Plate incorporation test only
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Key result
Species / strain:
S. typhimurium TA 1535
Metabolic activation:
without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity nor precipitates, but tested up to recommended limit concentrations
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Key result
Species / strain:
S. typhimurium TA 1537
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity nor precipitates, but tested up to recommended limit concentrations
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Key result
Species / strain:
S. typhimurium TA 98
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity nor precipitates, but tested up to recommended limit concentrations
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Key result
Species / strain:
S. typhimurium TA 100
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity nor precipitates, but tested up to recommended limit concentrations
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Key result
Species / strain:
E. coli WP2 uvr A
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity nor precipitates, but tested up to recommended limit concentrations
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
TEST SPECIFIC CONFOUNDING FACTORS
Effects of pH: none
Water solubility: soluble
Precipitation: The test item precipitated in the overlay agar in the test tubes from 333 to 5000 µg/plate. Precipitation of the test item in the overlay agar on the incubated agar plates was observed from 2500 µg/plate onward. The undissolved particles had no influence on the data recording.
Other confounding effects: none

COMPARISON WIT HISTORICAL CONTROL DATA:
ADDITIONAL INFORMATION ON CYTOTOXICITY: Toxic effects, evident as a reduction in the number of revertants (below the indication factor of 0.5), were observed in experiment II in strain TA 1535 with S9 mix at 5000 µg/plate only.

Any other information on results incl. tables

Summary of Experiment I

Metabolic Activation

Test Group

Dose Level (per plate)

TA 1535

Revertant Colony Counts (Mean ± SD)

TA 1537

Revertant Colony Counts (Mean ± SD)

TA 98

Revertant Colony Counts (Mean ± SD)

TA 100

Revertant Colony Counts (Mean ± SD)

WP2 uvrA

Revertant Colony Counts (Mean ± SD)

 

 

 

 

 

 

 

 

Without

Deionised water

 

9 ± 3

8 ± 1

21 ± 6

159 ± 15

39 ± 9

Activation

Untreated

 

11 ± 4

9 ± 5

26 ± 6

160 ± 10

33 ± 7

 

Test material

3 µg

11 ± 1

10 ± 4

21 ± 6

144 ± 9

44 ± 10

 

10 µg

12 ± 4

9 ± 5

22 ± 8

151 ± 13

37 ± 13

 

33 µg

12 ± 3

7 ± 2

22 ± 5

138 ± 29

33 ± 6

 

 

100 µg

9 ± 3

8 ± 3

24 ± 7

146 ± 22

42 ± 4

 

 

333 µg

9 ± 2

8 ± 3

27 ± 2

171 ± 11

43 ± 8

 

 

1000 µg

10 ± 4

10 ± 4

24 ± 6

159 ± 16

37 ± 6

 

 

2500 µg

9 ± 2P

9 ± 4P

23 ± 3P

153 ± 5P

38 ± 7P

 

 

5000 µg

10 ± 6P

8 ± 2P

21 ± 6P

159 ± 17P

39 ± 5P

 

NaN3

10 µg

1123 ± 119

 

 

1940 ± 23

 

 

4-NOPD

10 µg

 

 

310 ± 45

 

 

 

4-NOPD

50 µg

 

138 ± 12

 

 

 

 

MMS

2.0 µL

 

 

 

 

819 ± 11

 

 

 

 

 

 

 

 

With

Deionised water

 

11 ± 4

11 ± 4

29 ± 2

144 ± 13

49 ± 6

Activation

Untreated

 

13 ± 4

12 ± 5

35 ± 12

141 ± 20

50 ± 16

 

Test material

3 µg

11 ± 1

12 ± 5

32 ± 12

129 ± 12

48 ± 0

 

10 µg

9 ± 3

12 ± 3

25 ± 3

125 ± 9

37 ± 5

 

33 µg

12 ± 3

12 ± 3

37 ± 11

138 ± 7

42 ± 9

 

 

100 µg

10 ± 1

13 ± 4

26 ± 3

127 ± 27

40 ± 13

 

 

333 µg

10 ± 4

10 ± 1

32 ± 9

115 ± 18

45 ± 4

 

 

1000 µg

11 ± 2

9 ± 2

32 ± 5

100 ± 19

57 ± 4

 

 

2500 µg

8 ± 5P

8 ± 2P

34 ± 4P

127 ± 8P

44 ± 9P

 

 

5000 µg

14 ± 3P

10 ± 6P

32 ± 3P

142 ± 16P

49 ± 4P

 

2-AA

2.5 µg

466 ± 35

138 ± 21

3221 ± 133

3153 ± 170

 

 

2-AA

10.0 µg

 

 

 

 

371 ± 70

 

 

 

 

 

 

 

 


Summary of Experiment II

Metabolic Activation

Test Group

Dose Level (per plate)

TA 1535

Revertant Colony Counts (Mean ± SD)

TA 1537

Revertant Colony Counts (Mean ± SD)

TA 98

Revertant Colony Counts (Mean ± SD)

TA 100

Revertant Colony Counts (Mean ± SD)

WP2 uvrA

Revertant Colony Counts (Mean ± SD)

 

 

 

 

 

 

 

 

Without

Deionised water

 

12 ± 3

10 ± 1

30 ± 2

183 ± 14

38 ± 9

Activation

Untreated

 

11 ± 1

11 ± 4

34 ± 2

183 ± 22

42 ± 5

 

Test material

33 µg

12 ± 3

11 ± 6

23 ± 7

186 ± 18

40 ± 3

 

100 µg

10 ± 3

12 ± 3

31 ± 4

176 ± 15

47 ± 4

 

333 µg

11 ± 1

11 ± 4

24 ± 1

200 ± 9

45 ± 8

 

 

1000 µg

10 ± 5

11 ± 2

29 ± 8

185 ± 12

34 ± 4

 

 

2500 µg

9 ± 2P

8 ± 5P

24 ± 8P

177 ± 23P

40 ± 5P

 

 

5000 µg

7 ± 3P

7 ± 3P

34 ± 1P

200 ± 17P

46 ± 4P

 

NaN3

10 µg

1047 ± 105

 

 

1940 ± 87

 

 

4-NOPD

10 µg

 

 

375 ± 46

 

 

 

4-NOPD

50 µg

 

134 ± 7

 

 

 

 

MMS

2.0 µL

 

 

 

 

650 ± 52

 

 

 

 

 

 

 

 

With

Deionised water

 

11 ± 5

13 ± 3

32 ± 8

186 ± 10

59 ± 3

Activation

Untreated

 

12 ± 2

17 ± 7

40 ± 7

156 ± 8

56 ± 11

 

Test material

33 µg

11 ± 4

15 ± 4

36 ± 8

198 ± 18

52 ± 6

 

100 µg

11 ± 4

12 ± 4

38 ± 4

176 ± 14

52 ± 2

 

333 µg

12 ± 3

12 ± 3

33 ± 4

175 ± 9

54 ± 11

 

 

1000 µg

10 ± 1

16 ± 4

40 ± 1

195 ± 16

60 ± 7

 

 

2500 µg

12 ± 3P

11 ± 1P

36 ± 8P

182 ± 17P

49 ± 2P

 

 

5000 µg

3 ± 2P

12 ± 1P

35 ± 4P

195 ± 18P

50 ± 8P

 

2-AA

2.5 µg

361 ± 50

134 ± 7

4010 ± 761

1542 ± 202

 

 

2-AA

10.0 µg

 

 

 

 

508 ± 22

 

 

 

 

 

 

 

 

Key to Plate Postfix Codes:              

P: Precipitate

Key to positive controls:

NaN3: sodium azide

4 -NOPD: 4 -nitro-o-phenylene-diamine

MMS: methyl methane sulfonate

2-AA: 2 -aminoanthracene

Applicant's summary and conclusion

Conclusions:
In conclusion, it can be stated that during the described mutagenicity test and under the experimental conditions reported, the test item did not induce gene mutations by base pair changes or frameshifts in the genome of the strains used.
Therefore, Titanium zirconium oxide is considered to be non-mutagenic in this Salmonella typhimurium and Escherichia coli reverse mutation assay.
Executive summary:

The test item Titanium zirconium oxide was assessed for its potential to induce gene mutations according to the plate incorporation test (experiment I) and the pre-incubation test (experiment II) usingSalmonella typhimuriumstrains TA 1535, TA 1537, TA 98, TA 100, and theEscherichia colistrain WP2 uvrA.

The assay was performed in two independent experiments both with and without liver microsomal activation. Each concentration and the controls were tested in triplicate. The test item was tested at the following concentrations:

Pre-Experiment/Experiment I:       3; 10; 33; 100; 333; 1000; 2500; and 5000 µg/plate

Experiment II:                                33; 100; 333; 1000; 2500; and 5000 µg/plate

The test item precipitated in the overlay agar in the test tubes from 333 to 5000 µg/plate. Precipitation of the test item in the overlay agar on the incubated agar plates was observed from 2500 µg/plate onward. The undissolved particles had no influence on the data recording.

The plates incubated with the test item showed normal background growth up to 5000 µg/plate with and without S9 mix in all strains used.

Toxic effects, evident as a reduction in the number of revertants (below the indication factor of 0.5), were observed in experiment II in strain TA 1535 with S9 mix at5000 µg/plate only.

No substantial increase in revertant colony numbers of any of the five tester strains was observed following treatment with Titanium zirconium oxide at any concentration level, neither in the presence nor absence of metabolic activation (S9 mix). There was also no tendency of higher mutation rates with increasing concentrations in the range below the generally acknowledged border of biological relevance.

Appropriate reference mutagens were used as positive controls. They showed a distinct in­crease in induced revertant colonies.