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Toxicological information

Genetic toxicity: in vitro

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Administrative data

Endpoint:
in vitro gene mutation study in bacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
9 July - 23 July 2012
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
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method B.13/14 (Mutagenicity - Reverse Mutation Test Using Bacteria)
Deviations:
no
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay

Test material

Constituent 1
Chemical structure
Reference substance name:
Yttrium oxide (Y2O3), europium-doped
EC Number:
271-591-2
EC Name:
Yttrium oxide (Y2O3), europium-doped
Cas Number:
68585-82-0
Molecular formula:
Y2O3:Eu
IUPAC Name:
Yttrium oxide
Test material form:
solid: particulate/powder
Details on test material:
- Name of test material (as cited in study report): Yttrium Oxide, Europium-Doped
- Physical state: white powder

Method

Target gene:
- S. typhimurium: Histidine gene
- E. coli: Tryptophan gene
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:
Rat liver S9-mix induced by a combination of phenobarbital and ß-naphthoflavone
Test concentrations with justification for top dose:
Experiment 1
Preliminary test (TA100 and WP2uvrA):
Without and with S9-mix: 3, 10, 33, 100, 333, 1000, 3330 and 5000 µg/plate
Main study (TA1535, TA1537 and TA98):
Without and with S9-mix: 100, 333, 1000, 3330 and 5000 µg/plate
Experiment 2 (all strains):
Without and with S9-mix: 100, 333, 1000, 3330 and 5000 µg/plate
Vehicle / solvent:
- Solvent used: DMSO
- Justification for choice of solvent/vehicle:
A homogeneous suspension could be made in DMSO and DMSO is accepted and approved by authorities and international guidelines.
The stock solution was treated with ultrasonic waves to obtain a homogeneous suspension. Test substance concentrations were used within 2 hours after preparation.
Controlsopen allclose all
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
Positive controls:
yes
Positive control substance:
methylmethanesulfonate
Remarks:
without S9 Migrated to IUCLID6: 650 µg/plate in DMSO for TA100
Negative solvent / vehicle controls:
yes
Positive controls:
yes
Positive control substance:
2-nitrofluorene
Remarks:
without S9 Migrated to IUCLID6: 10 µg/plate in DMSO for TA98 and 15 µg/plate for TA1537
Negative solvent / vehicle controls:
yes
Positive controls:
yes
Positive control substance:
4-nitroquinoline-N-oxide
Remarks:
without S9 Migrated to IUCLID6: 10 µg/plate in DMSO for WP2uvrA
Negative solvent / vehicle controls:
yes
Positive controls:
yes
Positive control substance:
sodium azide
Remarks:
without S9 Migrated to IUCLID6: 5 µg/plate in saline for TA1535
Positive controls:
yes
Positive control substance:
other: ICR-191 2.5 ug/plate in DMSO for TA1537
Remarks:
without S9
Negative solvent / vehicle controls:
yes
Positive control substance:
other: 2-aminoanthracene in DMSO for all tester strains
Remarks:
with S9
Details on test system and experimental conditions:
METHOD OF APPLICATION: in agar (plate incorporation)

DURATION
- Exposure duration: 48 hour

NUMBER OF REPLICATIONS:
- Doses of the test substance were tested in triplicate in each strain. Two independent experiments were conducted.

NUMBER OF CELLS EVALUATED: 10E8 per plate

DETERMINATION OF CYTOTOXICITY
- Method: The reduction of the bacterial background lawn, the increase in the size of the microcolonies and the reduction of the revertant colonies.

OTHER EXAMINATIONS:
- The presence of precipitation of the test compound on the plates was determined.
Evaluation criteria:
A test substance is considered negative (not mutagenic) in the test if:
a) The total number of revertants in tester strain TA100 is not greater than two (2) times the concurrent control, and the total number of revertants in tester strains TA1535, TA1537, TA98 or WP2uvrA is not greater than three (3) times the concurrent control.
b) The negative response should be reproducible in at least one independently repeated experiment.

A test substance is considered positive if:
a) A two-fold (TA100) or more or a three-fold (TA1535, TA1537, TA98, WP2uvrA) or more increase above solvent control in the mean number of revertant colonies is observed in the test substance group.
b) In case a repeat experiment is performed when a positive response is observed in one of the tester strains, the positive response should be reproducible in at least one independently repeated experiment.

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:
no cytotoxicity nor precipitates, but tested up to recommended limit concentrations
Vehicle 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:
no cytotoxicity, but tested up to precipitating concentrations
Vehicle controls validity:
valid
Positive controls validity:
valid
Additional information on results:
TEST-SPECIFIC CONFOUNDING FACTORS
- Precipitation: Precipitation of Yttrium Oxide was not observed at the start of the incubation period, however precipitation of Yttrium Oxide was observed on the plates at a concentration of 5000 μg/plate at the end of the incubation period. In addition, in tester strain WP2uvrA also precipitate was observed at 3330 μg/plate (second experiment).

RANGE-FINDING/SCREENING STUDIES:
- No toxicity or mutagenicity was observed up to and including the top dose of 5000 µg/plate

COMPARISON WITH HISTORICAL CONTROL DATA:
- The negative and strain-specific positive control values were within our laboratory historical control data ranges indicating that the test conditions were adequate and that the metabolic activation system functioned properly.

ADDITIONAL INFORMATION ON CYTOTOXICITY:
- No toxicity or mutagenicity was observed up to and including the top dose of 5000 µg/plate

Applicant's summary and conclusion

Conclusions:
In an Ames test with Salmonella typhimurium spp. and Escherichia coli performed according to OECD/EC guidelines and GLP principles, the test material was found to be non-mutagenic with or without metabolic activation.
Executive summary:

An Ames test was performed according to current OECD/EC guidelines and GLP principles with Yttrium oxide, europium-doped. All bacterial strains ( TA1535, TA1537, TA98, TA100 and WP2uvrA) showed negative responses over the entire dose range, i.e. no significant dose-related increase in the number of revertants in two independently repeated experiments with or without metabolic activation. No toxicity was noted but testing was performed up to limit concentrations, precipitation was observed on the plates at a concentration of 5000 μg/plate at the end of the incubation period. In addition in tester strain WP2uvrA also precipitate was observed at 3330 μg/plate (second experiment). The negative and strain-specific positive control values were within the laboratory historical control data ranges indicating that the test conditions were adequate and that the metabolic activation system functioned properly. Based on the results of this study it is concluded that Yttrium Oxide, Europium-Doped is not mutagenic in the Salmonella typhimurium reverse mutation assay and in the Escherichia coli reverse mutation assay with or withouth metabolic activation.