Registration Dossier

Administrative data

Endpoint:
in vitro gene mutation study in bacteria
Remarks:
Type of genotoxicity: gene mutation
Type of information:
experimental study
Adequacy of study:
other information
Study period:
from August to September 2000
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: comparable to guideline study with acceptable restrictions (no E. coli WP2 or S. typhimurium TA102 strain tested)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2001
Report Date:
2001

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
yes
Remarks:
- no E. coli WP2 or S. typhimurium TA102 strain tested; only one experiment (direct plate incorporation procedure) was performed
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): ZK 74834
- Batch No.: 57046805
- Stability under test conditions: The solution and further dilutions were prepared immediately betore addition to the test bacteria.

Method

Target gene:
Histidine gene locus
Species / strain
Species / strain:
other: TA 98, TA 100, TA 1535, TA 1537 and TA 1538
Additional strain characteristics:
not applicable
Metabolic activation:
with and without
Metabolic activation system:
Aroclor 1254 induced male Sprague-Dawley rat liver S9 mix
Test concentrations with justification for top dose:
25, 50, 100, 250, 500, 1000, 2500, 5000 µg/plate
Vehicle:
DMSO
Controls
Negative controls:
no
Solvent controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: 4-nitro-o-phenylenediamine (only TA 1537), 2-nitrofluorene (only TA 1538 and 98), sodium azide (only TA 1535 and 100), benzo(a)pyrene (only TA 98 and 100), cyclophosphamide (only TA 1535), 2-aminoanthracene (all strains)

Results and discussion

Test results
Species / strain:
other: TA 98, TA 100, TA 1535, TA 1537 and TA 1538
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity:
no, but tested up to limit concentrations
Vehicle controls valid:
yes
Negative controls valid:
not applicable
Positive controls valid:
yes
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.

Any other information on results incl. tables

The counts recorded on appropriate negative control plates confirmed the characteristically spontaneous reversion rates of the tester strains. The total colony counts of the 10 -6 dilution of bacterial culture confirmed the viability and high cell density of the cultures of the individual strains.

Appropriate positive control chemicals induced marked increases in revertant colony numbers with all strains.

None of the five tester strains showed increased reversion to prototrophy in assays with the test substance at any of the 8 concentrations tested between 25 and 5000 µg/plate, either in the absence or precence of S9 mix.

Growth inhibition of the background lawn was observed at 2500 and 5000 µg/plate in the experiments with S9 mix and generally from 500 µg/plate onwards in the experiments without S9 mix. Precipitates in the agar were found starting at 500 µg/plate onwards in all strains without and with S9 mix.

Applicant's summary and conclusion

Executive summary:

The mutagenic potential of the test substance was evaluated in a Salmonella/microsome test with the S. typhimurium strains TA 98, TA 100, TA 1535, TA 1537 and TA 1538 in the presence and absence of S9 mix according to OECD TG 471. Evidence of mutagenic activity was not seen up to the maximum recommended dose level of 5000 µg/plate. No substantial increases in revertant colony numbers of any of the five tester strains were observed at any dose level in the presence and absence of metabolic activation. Therefore, the test substance was considered to be non-mutagenic in the Salmonella typhimurium reverse mutation assay.