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Toxicological information

Genetic toxicity: in vitro

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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:
8 October 1997 to 10 November 1997
Reliability:
1 (reliable without restriction)

Data source

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

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
not specified
Qualifier:
according to
Guideline:
OECD Guideline 472 (Genetic Toxicology: Escherichia coli, Reverse Mutation Assay)
Deviations:
not specified
Qualifier:
according to
Guideline:
EU Method B.13/14 (Mutagenicity - Reverse Mutation Test Using Bacteria)
Deviations:
not specified
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Test material form:
solid: particulate/powder
Remarks:
migrated information: powder
Details on test material:
- Name of test material (as cited in study report): Epyrron
- Physical state: Off white powder
- Analytical purity: 55%
- Composition of test material, percentage of components: Main component 55%; Other 22%, 18%;
- Lot/batch No.: GV-1458 K1
- Expiration date of the lot/batch: 24 September 1998
- Stability under test conditions: Stable
- Storage condition of test material: At room temperature in the dark.

Method

Target gene:
Histidine-requiring S. typhimurium, and
Tryptophan-requiring E. coli
Species / strain
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2
Details on mammalian cell type (if applicable):
- Properly maintained: Yes
- Periodically "cleansed" against high spontaneous background: Yes, E. coli
Metabolic activation:
with and without
Metabolic activation system:
S9-fraction
Test concentrations with justification for top dose:
Up to 3330 µg/plate.
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: Ethanol
- Justification for choice of solvent/vehicle: No data
Controls
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
4-nitroquinoline-N-oxide
9-aminoacridine
sodium azide
methylmethanesulfonate
other: daunomycine, 2-aminoanthracene
Details on test system and experimental conditions:
METHOD OF APPLICATION: In agar

DURATION
- Preincubation period: No data
- Exposure duration: 48 hours
- Expression time (cells in growth medium): 48 hours
- Selection time (if incubation with a selection agent): 48 hours
- Fixation time (start of exposure up to fixation or harvest of cells): 48 hours

SELECTION AGENT (mutation assays): Incubation time

DETERMINATION OF CYTOTOXICITY
- Method: relative total growth - number of revertnants
Evaluation criteria:
The test substance is considered negative (not mutagenic) in the test if:
- The total number of revertants in any tester strain at any concentration is not greater than two times the solvent control value, with or without metabolic activation.
- The negative response should be reproducible in at least one independently repeated experiment.

The test substances is considered positive (mutagenic) in the test if:
- It induces at least a 2-fold, dose related increase in the number of revertants with respect to the number induced by the solvent control in any of the tester strains, either with or without metabolic activation. However, any mean plate count of less than 20 is considered to be not significant.
- The positive response should be reproducible in at least one independently repeated experiment.

Results and discussion

Test results
Species / strain:
S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
not determined
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
TEST-SPECIFIC CONFOUNDING FACTORS
- Precipitation: The test substance precipitated in top agar at concentration of 1000 and 3330 µg/plate. Precipitation of the test substance on the plates was observed at the concentration of 3330 µg/plate at the start and at the end of the incubation period in all tester strains.

RANGE-FINDING/SCREENING STUDIES: The test substance was tested in the tester strains TA100 and WP2uvrA with concentration of 3, 10, 33, 100, 333, 1000, 3330, and 5000 µg/plate in the absence and presence of S9-mix.

The test substance precipitated in the top agar at concentrations of 1000 µg/plate and upwards.
Precipitate of the test substance on the plates was observed at concentrations of 3330 and 5000 µg/plate at the start and at the end of the incubation period in tester strain TA100 and WP2uvrA.

To determine the toxicity of the test substance, the reduction of the bacterial background lawn, the increase in the size of the microcolonies and the reduction of the revertant colonies were observed.
In strain TA100, in the absence of S9-mix, a moderate reduction of the bacterial background lawn and in the number of His+ revertants was observed at the concentration of 3330 µg/plate. An extreme reduction of the bacterial background lawn and an increase in the size of microcolonies was observed at the concentration of 5000 µg/plate.
In the presence of S9-mix, a slight reduction of the bacterial background lawn and in the number of His+ revertants was observed at the concentration of 3330 µg/plate. A moderate reduction of the bacterial background lawn and of the His+ revertants was observed at the concentration of 5000 µg/plate.
In tester strain WP2uvrA, no reduction of the bacterial background lawn and no decrease in the number of revertant colonies, which was less than the minimal value of the historical control data range was observed at all concentration tested.

COMPARISON WITH HISTORICAL CONTROL DATA: All other concentrations, not present in tables 1 and 2 below, and strain Wp2uvrA showed no reduction in the bacterial background lawn or showed no reduction in the number of revertants, which was less than the minimal value of the historical control data range.

The negative and strain-specific positive control values were within our laboratory background historical control data ranges indicating that the test conditions were adequate and that the metabolic activation system functioned properly.
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.

Any other information on results incl. tables

Table 1: Reduction in the Bacterial Background Lawn

Strain Dose (µg/plate) Without S9-Mix With S9-Mix

TA1535

3330  -   - 
TA1537 3330 Slight  - 
TA98 3330  -   - 
TA1001 3330
5000
Moderate
Extreme
Slight
Moderate
 - No reduction in the number of revertant colonies, which was less than the minimal value of the historical control data range.
1The first experiment was tested in the dose range finding test.

Table 2: Reduction in the Number of Revertants

Strain Dose (µg/plate) Without S9-Mix With S9-Mix
TA1537 3330  -   - 
TA98 3330  -   - 
TA1001 3330
5000
Moderate
Extreme2
Slight
Moderate
 - No reduction in the number of revertant colonies, which was less than the minimal value of the historical control data range.
1The first experiment was tested in the dose range finding test.
2Microcolonies

Number of Revertants: All bacterial strains showed negative responses over the entire dose range, i.e. no dose-related, two-fold, increase in the number of revertants in two independently repeated experiments.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
negative

Under test conditions, the test substance is considered non-mutagenic.