Dicerium trioxide

Genetic toxicity: in vitro

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

Test material information

Constituent 1

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 results

Test results 1

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

Test results 2

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

Test results 3

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

Test results 4

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

Test results 5

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.