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Toxicological information

Genetic toxicity: in vitro

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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:
2012-05-08 to 2012-06-08
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2012
Report Date:
2012

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Qualifier:
according to
Guideline:
EU Method B.13/14 (Mutagenicity - Reverse Mutation Test Using Bacteria)
GLP compliance:
yes (incl. certificate)
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Remarks:
migrated information: powder
Details on test material:
- Name of test material (as cited in study report): Tellurium
- Substance type: inorganic

Method

Species / strainopen allclose all
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Species / strain / cell type:
E. coli WP2 uvr A
Metabolic activation:
with and without
Metabolic activation system:
S9 mix; phenobarbital/β-naphthoflavoneinduced rat liver
Test concentrations with justification for top dose:
Range finding test: 5000, 2500, 1000, 316, 100, 31.6 and 10 μg/plate (TA 98 and TA 100 with and without metabolic activation).
Initial mutation test: 5000, 1581, 500, 158.1, 50, 15.81 and 5 μg test item/plate.
Confirmatory mutation test: 5000, 1581, 500, 158.1, 50, 15.81, 5 and 1.581 μg test item/plate.
Complementary confirmatory mutation test: 158.1; 50; 15.81; 5; 1.581, 0.5, 0.1581 and 0.05 μg test item/plate.
Vehicle / solvent:
1 % (v/v) methyl cellulose solution was used as vehicle to prepare the stock formulation of the test material.
Test formulations were freshly prepared at the beginning of the experiments in the testing laboratory by
diluting the stock formulation using the selected vehicle.
Controls
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
Positive controls:
yes
Positive control substance:
9-aminoacridine
sodium azide
methylmethanesulfonate
other: 4-nitro-1,2-phenylenediamine (NPD); 2-aminoanthracene
Details on test system and experimental conditions:
METHOD OF APPLICATION: Preliminary and initial experiment: in agar (plate incorporation)
For confirmatory and complementary confirmatory tests preincubation method was used

DURATION
- Preincubation period: 20 min
- Exposure duration: 48 h

SELECTION AGENT (mutation assays):

NUMBER OF REPLICATIONS: 3 plates/concentration
Evaluation criteria:
Criteria for Validity:
The study was considered valid if:
- the number of revertant colonies of the negative (vehicle/solvent) and positive controls were in the historical control range in all strains of the main tests;
- at least five analyzable concentrations were presented in all strains of the main tests.

Criteria for a Positive Response:
A test item was considered mutagenic if:
- a dose–related increase in the number of revertants occurred and/or;
- a reproducible biologically relevant positive response for at least one of the dose groups occurred in at least one strain with or without metabolic
activation.
An increase was considered biologically relevant if:
- in all strains: the number of reversion was more than twice higher than the reversion rate of the vehicle control.

Results and discussion

Test resultsopen allclose all
Species / strain:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Species / strain:
E. coli WP2 uvr A
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
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

Based on the results of the Preliminary Solubility Test, 1 % (v/v) methyl cellulose solution was selected for vehicle of the test item in the study. Concentrations of 5000; 2500; 1000; 316; 100; 31.6 and 10 μg/plate were examined in the Preliminary Range Finding Test. Based on the results of the Preliminary Range Finding Test, the test item concentrations in the Initial Mutation Test were 5000, 1581, 500, 158.1, 50, 15.81 and 5 μg test item/plate. Examined concentrations in the Confirmatory Mutation Test were 5000, 1581, 500, 158.1, 50, 15.81, 5 and 1.581 μg test item/plate. Examined concentrations in the Complementary Confirmatory Mutation Test were 158.1; 50; 15.81; 5; 1.581, 0.5, 0.1581 and 0.05 μg test item/plate.

In the Initial Mutation Test, Confirmatory Mutation Test and Complementary Confirmatory Mutation Test, none of the observed revertant colony numbers were above the respective biological threshold value. There were no consistent dose-related trends and no indication of any treatment effect. In all test item treated groups, the numbers of revertant colonies were below the biological relevance when compared with the solvent controls and were within the historical control range and were within the normal biological variability of the test system.

Slight inhibitory, cytotoxic effect of the test item was observed in the Initial Mutation Test in Salmonella typhimurium TA98 bacterial strain at 5000 μg/plate concentration with metabolic activation and in Escherichia coli WP2 uvrA bacterial strain at 5000 μg/plate concentration without metabolic activation. Reduced numbers of revertant colonies compared to the vehicle control plates were also observed in Salmonella typhimurium TA100 strain at 5000 μg/plate concentration without metabolic activation, and in Salmonella typhimurium TA1535 and Escherichia coli WP2 uvrA strains at 5000 μg/plate concentration with metabolic activation, although no effect on the background lawn was observed.

Similar, but stronger cytotoxic effect was observed using the pre-incubation method (Confirmatory Mutation Test and Complementary Confirmatory Mutation Test) in Salmonella typhimurium TA100, TA1535 and TA1537 strains at 158.1 and 50 μg/plate concentrations without metabolic activation; and in Escherichia coli WP2 uvrA strain at 5000, 1581 and 500 μg/plate concentrations without metabolic activation.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
negative

In conclusion, the test item Tellurium had no mutagenic activity in the bacterium tester strains under the test conditions used in this study.
Executive summary:

In a reverse gene mutation assay in bacteria according to OECD guideline 471, strains TA 1535, TA 1537, TA98 and TA100 of S. typhimurium and E. coli WP2 uvrA were exposed to Tellurium, (powder 99.95 % a.i.), at concentrations up to 5000 µg/plate in the presence and absence of mammalian metabolic activation, (S9 mix; phenobarbital/β-naphthoflavone induced rat liver).

The initial Mutation Test was performed as plate incorporation method; the confirmatory and complementary assays were performed according to the pre-incubation method.

 

In the Initial Mutation Test, Confirmatory Mutation Test and Complementary Confirmatory Mutation Test, none of the observed revertant colony numbers were above the respective biological threshold value. There were no consistent dose-related trends and no indication of any treatment effect. In all test item treated groups, the numbers of revertant colonies were below the biological relevance when compared with the solvent controls and were within the historical control range and were within the normal biological variability of the test system.

Slight inhibitory, cytotoxic effect of the test item was observed in the Initial Mutation Test in Salmonella typhimurium TA98 bacterial strain at 5000 μg/plate concentration with metabolic activation and in Escherichia coli WP2 uvrA bacterial strain at 5000 μg/plate concentration without metabolic activation. Reduced numbers of revertant colonies compared to the vehicle control plates were also observed in Salmonella typhimurium TA100 strain at 5000 μg/plate concentration without metabolic activation, and in Salmonella typhimurium TA1535 and Escherichia coli WP2 uvrA strains at 5000 μg/plate concentration with metabolic activation, although no effect on the background lawn was observed.

Similar, but stronger cytotoxic effect was observed using the pre-incubation method (Confirmatory Mutation Test and Complementary Confirmatory Mutation Test) in Salmonella typhimurium TA100, TA1535 and TA1537 strains at 158.1 and 50 μg/plate concentrations without metabolic activation; and in Escherichia coli WP2 uvrA strain at 5000, 1581 and 500 μg/plate concentrations without metabolic activation.

The mean values of revertant colonies of the solvent control plates were within the historical control range, the reference mutagens showed the expected increase in the number of revertant colonies, the viability of the bacterial cells was confirmed by a plating experiment in each test. At least five analyzable concentrations were presented in all strains of the main tests. The tests were considered to be valid.

 

 

In conclusion there was no evidence of induced mutant colonies over background.