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Administrative data

Endpoint:
in vitro gene mutation study in bacteria
Type of information:
experimental study
Adequacy of study:
key study
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 guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
GLP compliance:
yes (incl. QA statement)
Type of assay:
bacterial reverse mutation assay

Test material

Constituent 1
Chemical structure
Reference substance name:
Dicerium trioxide
EC Number:
215-718-1
EC Name:
Dicerium trioxide
Cas Number:
1345-13-7
Molecular formula:
Ce2O3
IUPAC Name:
dicerium trioxide
Test material form:
solid: particulate/powder
Details on test material:
Fine Light Yellow Powder

Method

Target gene:
Species: Salmonella typhimurium LT2
Strains: TA97a, TA98, TA100, TA102 and TA1535
Species / strain
Species / strain / cell type:
S. typhimurium, other: TA97a, TA98, TA100, TA102 and TA1535
Metabolic activation:
with and without
Metabolic activation system:
S9-mix
Test concentrations with justification for top dose:
5000 µg/plate
Vehicle / solvent:
Water
Controls
Negative solvent / vehicle controls:
yes
Remarks:
Dimethylsulfoxide (DMSO) and Demineralised water were used
Positive controls:
yes
Positive control substance:
sodium azide
benzo(a)pyrene
other: 4-Nitro-1,2-phenylene Diamine, 2-Amino-Anthracene
Details on test system and experimental conditions:
All Salmonella typhimurium strains were obtained from TRINOVA BioChem GmbH (batch:
TA97a: 4997D, TA98: 5011D, TA100: 4996D, TA102: 4982D, TA1535: 5012D) and were
stored as lyophilizates in the refrigerator at 2-8 °C.
The lyophilizates were used to prepare permanent cultures which were filled into vials and
stored at < - 75 °C.

Eight hours before the start of each experiment, an aliquot of a permanent culture per
strain to be used was taken from the deep freezer to inoculate a culture vessel containing
nutrient broth. After incubation overnight for eight hours at 37 ± 1 °C, the cultures were
used in the experiment. During the test, the cultures were stored at room temperature as
to prevent changes in the titre.

All vessels used are made of glass or sterilizable plastic. They were sterilized before use
by autoclaving.
The following vessels were used:
1. Schott-bottles, glass vials, and culture flasks for solutions and media
2. Plastic petri plates
3. test tubes for top-agar-bacteria-substance mix
Evaluation criteria:
The colonies were counted visually and the numbers were recorded. A validated spread-
sheet software (Microsoft Excel®) was used to calculate mean values and standard devia-
tions of each treatment, solvent control and positive control.
The mean values and standard deviations of each threefold determination was calculated
as well as the increase factor f(l) of revertant induction (mean revertants divided by mean
spontaneous revertants) of the test item suspensions and the positive controls. Additional-
ly, the absolute number of revertants (Rev. Abs.) (mean revertants minus mean spontane-
ous revertants) was given.
A substance is considered to have mutagenic potential, if a reproducible increase of re-
vertant colonies per plate exceeding an increase factor of 2 in at least one strain can be
observed. A concentration-related increase over the range tested is also taken as a sign of
mutagenic activity.

Results and discussion

Test resultsopen allclose all
Species / strain:
S. typhimurium TA 97
Remarks:
TA97a
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 98
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 100
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 102
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 1535
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid

Applicant's summary and conclusion

Conclusions:
Based on the results of this study it is concluded that Cerium Oxide is not mutagenic in the Salmonella typhimurium test strains TA97a, TA98, TA100, TA102 and TA1535 in the absence and presence of metabolic activation under the experimental conditions in the present study.