Rhodium chloride (RhCl3), hydrate

Genetic toxicity: in vitro

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:

17-29 May 2006

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study, to GLP

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2006

Report date:

2006

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.13/14 (Mutagenicity - Reverse Mutation Test Using Bacteria)

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.5100 - Bacterial Reverse Mutation Test (August 1998)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Rhodium trichloride hydrate

IUPAC Name:

Rhodium trichloride hydrate

Constituent 2

Reference substance name:

20765-98-4, 13569-65-8

IUPAC Name:

20765-98-4, 13569-65-8

Test material form:

other: liquid

Details on test material:

- Name of test material (as cited in study report): Rhodium (III) chloride hydrate, solution
- Substance type: No data
- Physical state: Red liquid
- Analytical purity: No data
- Impurities (identity and concentrations): No data
- Composition of test material, percentage of components: 15.95% RhCl3 without water, 1.78% HCl
- Isomers composition: Not applicable
- Purity test date: No data
- Lot/batch No.: 103/05
- Expiration date of the lot/batch: 31 December 2006
- Stability under test conditions: No data
- Storage condition of test material: Room temperature

Method

Target gene:

Histidine

Species / strain

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102

Details on mammalian cell type (if applicable):

Not applicable

Additional strain / cell type characteristics:

not specified

Metabolic activation:

with and without

Metabolic activation system:

Microsomal fraction (S9) prepared from the liver of male Wister rats induced with phenobarbital and β-naphtoflavone on three consecutive days by oral gavage

Test concentrations with justification for top dose:

Experiment 1: 0.0316, 0.1, 0.316, 1, 2.5 and 5 μL/plate
Experiment 2: 0.25, 0.5, 1, 2, 3, 4 and 5 μL/plate

Pre-experiment (strains TA 98 and TA 100 only): 0.01, 0.0316, 0.1, 0.316, 1, 2.5 and 5 μL/plate

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: water
- Justification for choice of solvent/vehicle: Test guideline recommends use of aqueous solvent wherever possible

Controls

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

sodium azide

methylmethanesulfonate

other: 2-aminoanthracene (2-AA) and 4-nitro-o-phenylenediamine (4-NOPD)

Remarks:

Without S9: Sodium azide (NaN3; TA 100 and TA 1535 at 10 μg/plate); 4-NOPD (TA 98 at 10 μg/plate and TA 1537 at 40 μg/plate); Methyl methane sulfonate (MMS; TA 102 at 1 μL/plate). With S9: 2-AA (TA 102 at 10 μg/plate; All other strains at 2.5 μg/plate)

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium; in agar (plate incorporation)

DURATION
- Preincubation period: Not applicable
- Exposure duration: 48 hours
- Expression time (cells in growth medium): Not applicable
- Selection time (if incubation with a selection agent): Not applicable
- Fixation time (start of exposure up to fixation or harvest of cells): Not applicable

SELECTION AGENT (mutation assays): Not applicable
SPINDLE INHIBITOR (cytogenetic assays): Not applicable
STAIN (for cytogenetic assays): Not applicable

NUMBER OF REPLICATIONS: Plates prepared in triplicate for each experiment

NUMBER OF CELLS EVALUATED: Not applicable

DETERMINATION OF CYTOTOXICITY
- Method: other: thinning/absence of background lawn, reduction in number of mutant colonies

OTHER EXAMINATIONS:
- Determination of polyploidy: Not applicable
- Determination of endoreplication: Not applicable

Evaluation criteria:

A test item is considered as mutagenic if there is a clear and dose-related increase in the number of revertants and/or a biologically relevant positive response for at least one of the dose groups occurs in at least one tester strain with or without S9.

A biologically relevant increase was taken as a 2-fold increase in mutants for TA 100 and TA 102 and a 3-fold increase in TA 98, TA 1535 and TA 1537, compared to the spontaneous reversion rate.

A test item producing neither a dose related increase in the number of revertants nor a reproducible biologically relevant positive response at any of the dose groups is considered to be non-mutagenic in this system.

Statistics:

Not applicable. According to the OECD guidelines, the biological relevance of the results will be the criterion for the interpretation of results. Hence, a statistical evaluation is not regarded as necessary.

Results and discussion

Test results

Test results 1

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Test results 2

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

Only in experiment 2

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Test results 3

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Test results 4

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Test results 5

Species / strain:

S. typhimurium TA 102

Metabolic activation:

with and without

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS
- Effects of pH: No data
- Effects of osmolality: No data
- Evaporation from medium: No data
- Water solubility: No data
- Precipitation: None
- Other confounding effects: No contamination noted

RANGE-FINDING/SCREENING STUDIES: Reduction in background lawn seen at 5 μL/plate in TA 98 (with and without S9). In TA 100, cytotoxicity was observed at 2.5 μL/plate and above without S9 and at 1 μL/plate and above with S9.

COMPARISON WITH HISTORICAL CONTROL DATA: Spontaneous frequencies were within the historical control data range.

MUTAGENICITY: Neither experiment noted any biologically relevant increases in revertant colony numbers in tester strains TA 1535 and TA 1537. A dose-response relationship was found in tester strains TA 98, TA 100 and TA 102 (with and without S9) in both experiments.

Experiment 1: Biologically relevant increases in revertant colony numbers were observed in TA 98 in a range from 0.316 to 2.5 μL/plate (without S9) and in a range from 0.316 to 1.11 μL/plate (with S9). In strain TA 100 biologically relevant increases in revertant colony numbers were noted from 0.316 to 1 μL/plate (without S9) and at a dose of 0.316 μL/plate (with S9). Biologically relevant increases of revertant colony numbers were observed in TA 102 in a range from 0.316 to 5 μL/plate (with and without S9). The threshold value of 2.0 was exceeded and a maximum mutation factor of 8.0 was reached in tester strain TA 102 at a dose of 2.5 μL/plate (without S9).

Experiment 2: No biologically relevant increases in revertant colony numbers were noted in tester strains TA 1535 and TA 1537. Biologically relevant increases in revertant colony numbers were observed in TA 98 in a range from 0.5 to 2 μL/plate (with and without S9). In strain TA 100 biologically relevant increases in revertant colony numbers were noted from 0.25 to 1 μL/plate (without S9) and at a dose of 0.5 μL/plate (with S9). Biologically relevant increases of revertant colony numbers were observed in TA 102 in a range from 0.5 to 5 μL/plate (without S9) and in a range from 0.25 to 5 μL/plate (with S9). The threshold value of 2.0 was exceeded and a maximum mutation factor of 8.2 was reached in tester strain TA 102 at a dose of 4 μL/plate (without S9).

The positive controls (NaN3, 4-NOPD, MMS and 2-AA) induced a distinct increase of revertant colonies indicating the validity of the experiments.

ADDITIONAL INFORMATION ON CYTOTOXICITY: Cytotoxic effects were noted in almost all tester strains evaluated in the two experiments.

Experiment 1: Toxic effects of the test item were observed in tester strain TA 98 at a dose of 5 μL/plate (with and without metabolic activation). In tester strains TA 100 and TA 1535 toxic effects of the test item were noted at a dose of 2.5 μL/plate and higher (without metabolic activation) and at a dose of 1 μL/plate and higher (with metabolic activation).

Experiment 2: In tester strain TA 98 toxic effects of the test item were observed at a dose of 4 μL/plate and higher (with and without metabolic activation). In tester strains TA 100 and TA 1535 toxic effects of the test item were noted at a dose of 2 μL/plate and higher (with and without metabolic activation). In tester strain TA 1537 toxic effects of the test item were observed at a dose of 4 μL/plate and higher (without metabolic activation) and at a dose of 3 μL/plate (with metabolic activation).

Remarks on result:

other: strain/cell type:

Remarks:

Migrated from field 'Test system'.

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information):
positive

In a guideline study, to GLP, rhodium (III) chloride hydrate solution exhibited mutagenic activity in a bacterial reverse mutation (Ames) assay using five Salmonella typhimurium strains (TA 98, 100, 1535, 1537 and 1538), when tested at up to cytotoxic concentrations in the presence and absence of a rat liver metabolic activation (S9) system.

Executive summary:

The potential of rhodium (III) chloride hydrate solution to induce gene mutations was studied in the Ames bacterial mutation assay (plate incorporation method) conducted according to OECD Test Guideline 471, and to GLP. The compound was tested in five strains of Salmonella typhimurium (TA98, TA100, TA102, TA1535 and TA1537).

 

Two independent experiments were carried out (each in triplicate), the first at concentrations of 0.0316, 0.1, 0.316, 1, 2.5 and 5 µL/plate and the second at 0.25, 0.5, 1, 2, 4 and 5 µL/plate, both with and without the presence of a rat microsomal activation fraction (S9).

 

No biologically relevant increases in mutant frequency were seen in either experiment with strains TA1535 or TA1537, either with or without S9. A dose-related increase in mutant frequency was observed with strains TA98, TA100 and TA102 at doses of 0.316 µL/plate or higher in experiment 1 and at 0.25 µL/plate and above in experiment 2, both with and without S9. The mutant frequency tended to be higher without S9. With the exception of TA1537 (in experiment 1), cytotoxicity was observed with all strains at concentrations of 2 µL/plate or higher, both with and without S9, and in addition at 1 µL/plate (in experiment 1), with S9.

 

Rhodium (III) chloride hydrate solution showed mutagenic activity in the Ames bacterial reverse mutation assay in strains TA98, TA100 and TA102 (with and without S9), indicating the ability of the test material to induce both base-pair and frameshift mutations in the gene sequence.