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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:
4 April 1986 – 28 April 1986
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study conducted according to OECD Guideline No. 471 and to GLP

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1986
Report date:
1986

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
yes
Remarks:
study did not include bacterial strains to detect cross-linking or oxidising agents
GLP compliance:
yes (incl. QA statement)
Type of assay:
bacterial reverse mutation assay

Test material

Constituent 1
Reference substance name:
Rhodium(3+) acetate
EC Number:
247-460-0
EC Name:
Rhodium(3+) acetate
Cas Number:
42204-14-8
Molecular formula:
C6H9O6Rh
IUPAC Name:
Rhodium(3+);triacetate
Details on test material:
- Name of test material (as cited in study report): rhodium(III) acetate “brown”
- Substance type: brown powder
- Physical state: solid
- Purity: no data
- Composition of test material, percentage of components: 39.54% rhodium
- Storage condition of test material: at room temperature

Method

Target gene:
Histidine
Species / strainopen allclose all
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Species / strain / cell type:
S. typhimurium TA 1538
Metabolic activation:
with and without
Test concentrations with justification for top dose:
Toxicity test: 0, 0.0005, 0.005, 0.05, 0.5, 5.0 and 50.0 mg/plate
1st test: 0, 0.12, 0.37, 1.11, 3.33 and 10.0 mg/plate
2nd test: 0, 0.5, 1.0, 2.0, 4.0 and 8.0 mg/plate
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: water
- Justification for choice of solvent/vehicle: no data
Controls
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: sodium azide; 2-nitrofluorene; 9-aminoacridine; 2-aminoanthracene
Details on test system and experimental conditions:
METHOD OF APPLICATION: in agar (plate incorporation)

DURATION
- Exposure duration: 72 hrs

NUMBER OF REPLICATIONS: 3

DETERMINATION OF CYTOTOXICITY
Thinning or absence of background lawn of non-revertant cells

S9 liver microsomal fraction was prepared from male Wistar-outbred rats (Bor:WISW) treated intraperitoneally with a single dose of 500 mg Aroclor 1254/kg bw in soya bean oil. Animals were killed 5 days after the injection, the livers removed and the S9 supernatant collected. Immediately before use, the S9 mix was prepared by mixing the S9 with a NADPH generating system to produce a final concentration of 10% S9.

In the absence of metabolic activation, sodium azide was used as a positive control for S. typhimurium TA100 and TA1535 at a concentration of 1.0 µg/0.1 ml water/plate, 2-nitrofluorene was used for S. typhimurium TA98 and TA1538 at 2.0 µg/0.1 ml DMSO/plate and 9-aminoacridine was used for S. typhimurium TA1537 at 80 µg/0.1 ml DMSO/plate. In the presence of metabolic activation, 2-aminoanthracene was used for all strains at 2.0 µg/0.1 ml DMSO/plate.
Evaluation criteria:
After incubation, the number of his+ revertant colonies was counted using an Artek Electronic Counter. A positive response was indicated by a two-fold or greater increase in the mean number of revertant colonies appearing in the test plates over and above the background spontaneous reversion rate observed with the vehicle control, together with evidence of a dose-response.

Results and discussion

Test resultsopen allclose all
Species / strain:
S. typhimurium TA 1535
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium, other: TA 1537; TA 1538
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium, other: TA 98; TA 100
Metabolic activation:
with and without
Genotoxicity:
positive
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
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: no data
- Other confounding effects: no data

RANGE-FINDING/SCREENING STUDIES: The test material was found to be very toxic for S. typhimurium TA98 at a dose level of 50.0 mg/plate. There was no evidence of toxicity at 5.0 mg/plate and below.

COMPARISON WITH HISTORICAL CONTROL DATA: no data

ADDITIONAL INFORMATION ON CYTOTOXICITY: In the first of the mutagenicity experiments, cytotoxicity was noted in strains TA1537 and TA1538 at a dose level of 10 mg/plate when tested both in the absence and presence of S9. This was evidenced by a strong decrease in the number of his+ revertants, a diminished background lawn of bacterial growth and the occurrence of microcolonies (pinpoints) in the plate. The repeat experiment, performed with intermediate dose levels, showed slight toxicity (a diminished background lawn of bacterial growth) for TA1537 and TA1538 at 8.0 mg/plate.
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
positive

No evidence of mutagenic activity was detected in S. typhimurium strains TA1535, TA1537 or TA1538 tested with rhodium (III) acetate “brown” in the absence or presence of a rat liver metabolic activation system (S9), with strains TA1537 and TA1538 being tested up to cytotoxic concentrations. Positive mutagenic activity was seen in S. typhimurium TA98 and TA100, both in the absence and presence of S9.
Executive summary:

In an OECD Test Guideline 471 study, conducted according to GLP, rhodium (III) acetate “brown” was examined for mutagenic activity in Salmonella Typhimurium (strains TA 1535, TA 1537, TA 1538, TA 98, and TA 100) in the presence and absence of Aroclor-induced rat liver metabolic activation system (S9). Two experiments were conducted (each in triplicate) with the test material dissolved in water at levels ranging up to 10 and 8 mg/plate, respectively, both with and without S9.

No evidence of mutagenic activity was seen in strains TA1535, TA1537 or TA1538, in the absence or presence of S9, with TA1537 and TA1538 being tested at up to cytotoxic concentrations. However, a doubling in the number of revertant colonies was seen in strains TA98 and TA100 at 3.33 mg/plate (in the first experiment) and at 4.0 mg/plate and above (in the second experiment using intermediate dose levels), in the absence and presence of S9. These findings were dose-related. Hence, rhodium acetate was mutagenic in S. typhimurium strains TA 98 and TA 100, when tested in the absence and presence of S9.