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:
key study
Study period:
from November to December 1996
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: comparable to guideline study with acceptable restrictions; the applied strains of bacteria may not detect certain oxidising mutagens, cross-linking agents

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1997
Report Date:
1997

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
yes
Remarks:
- TA 102 or E.coli WP2 strains are not included; only one experiment (direct plate incorporation procedure) was performed
GLP compliance:
no
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent

Method

Target gene:
Histidine gene locus
Species / strain
Species / strain / cell type:
S. typhimurium, other: TA 1535, TA 100, TA 1537, TA 1538 and TA 98
Additional strain / cell type characteristics:
not applicable
Metabolic activation:
with and without
Metabolic activation system:
Aroclor 1254 induced male Wistar rat liver S9 mix
Test concentrations with justification for top dose:
100, 250, 500, 1000, 2500, 5000 µg/plate








Vehicle / solvent:
phosphate buffer ((pH 7.4, 0.1 M)
Controls
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
9-aminoacridine
2-nitrofluorene
sodium azide
benzo(a)pyrene
cyclophosphamide
other: anthracen-2-amine

Results and discussion

Test results
Species / strain:
S. typhimurium, other: TA 1535, TA 100, TA 1537, TA 1538 and TA 98
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity nor precipitates, but tested up to recommended limit concentrations
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.

Any other information on results incl. tables

None of the five tester strains showed increased reversion to prototrophy in assays with ZK 156454 at 6 concentrations tested between 0.1 and 5.0 mg/plate, either in the absence or presence of S9 mix. Generally, growth inhibition of the background lawn was not observed. There were no precipitates in the agar. Negative controls and positive controls with known mutagens produced the expected numbers of revertant colonies.

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.