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:
1998
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: outdated guideline applied,

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1998
Report Date:
1998

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
yes
Remarks:
Escherichis coli not included
GLP compliance:
yes (incl. certificate)
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent

Method

Species / strain
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Metabolic activation:
with and without
Metabolic activation system:
rat liver S9 mix
Test concentrations with justification for top dose:
0 - 4 - 20 - 100 - 500 - 2500 - 5000 µg/plate
Vehicle / solvent:
DMSO
Controls
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
Positive controls:
yes
Positive control substance:
9-aminoacridine
2-nitrofluorene
sodium azide
other: 2-aminoanthracene
Details on test system and experimental conditions:
METHOD OF APPLICATION: in agar (plate incorporation);

DURATION
- Preincubation period: no
- Exposure duration: 48 h

NUMBER OF REPLICATIONS: 3

DETERMINATION OF CYTOTOXICITY
- Method: other: back groud lawn evaluation, number of spontaneous revertant colonies
Evaluation criteria:
The assay is considered valid if the following criteria are met:
- the solvent control data are within the laboratory's normal control range for the spontaneous mutant frequency.
- the positive controls induced increases in the mutation frequency which were both statistically significant and within the laboratory's normal range.

A test compound is classified as mutagenic if it has either of the following effects:
a) it produces at least a 2-fold increase in the mean number of revertants per plate of at least one of the tester strains over the mean number of revertants per plate of the appropriate vehicle control at complete bacterial background lawn.
b) it induces a dose-related increase in the mean number of revertants per plate of at least one of the tester strains over the mean number of revertants per plate of the appropriate vehicle control in at least two to three concentrations of the test compound at complete bacterial background lawn.

If the test substance does not achieve either of the above criteria, it is considered to show no evidence of mutagenic activity in this system.
The test results must be reproducible.

Results and discussion

Test results
Species / strain:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
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'.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
negative

The test item is not mutagenic in bacterial test systems either with or without exogenous metabolic activation at the dose levels investigated.
Executive summary:

The test item was tested for mutagenicity with the strains TA 100, TA 1535, TA 1537 and TA 98 of Salmonella typhimurium.

Two independent mutagenicity studies were conducted, each in the absence and in the presence of a metabolizing system derived from a rat liver homogenate.

For all studies, the compound was suspended in DMSO, and each bacterial strain was exposed to 6 dose levels. Doses for all studies ranged from 4 to 5000 µg/plate.

Control plates without mutagen showed that the number of spontaneous revertant colonies was within the laboratory's historical control range. All the positive control compounds showed the expected increase in the number of revertant colonies.

Toxicity:

In the mutagenicity experiments toxicity was not observed either with or without metabolic activation.

A toxicity test using histidine-enriched agar plates and a dilution of the tester strain TA 1 00 (designated TA 1 00 D) was performed in parallel with the second experiment.

The test compound proved to be not toxic to the bacterial strain.

Mutagenicity:

In the absence and in the presence of the metabolic activation system the test item did not result in relevant increases in the number of revertants in any of the bacterial strains.

The test item is not mutagenic in these bacterial test systems either with or without exogenous metabolic activation at the dose levels investigated.