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Toxicological information

Genetic toxicity: in vitro

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Administrative data

Endpoint:
in vitro gene mutation study in bacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2005-01-06 to 2005-02-07
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Remarks:
Only three strains are tested. However, an expert statement is added in the field "any other remarks" to justify the fact that no further testing is necessary.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2005
Report Date:
2005

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
yes
Remarks:
Only 3 bacterial strains used; the purity of the test substance is unknown and limited methodology is described
GLP compliance:
no
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Details on test material:
- Name of test material (as cited in study report): JNJ-7982559-AAA (T001329)
- Physical state: solid (powder)
- Appearance: Grey-brown powder
Specific details on test material used for the study:
Description: Pale purple powder
Batch number: 00434473
Date received: 2004-12-15
Storage conditions: Room temperature in the dark

Method

Target gene:
histidine locus
Species / strain
Species / strain:
other: TA98, TA100, and TA102
Details on mammalian cell lines (if applicable):
not applicable
Metabolic activation:
with and without
Metabolic activation system:
S9 mix, rat liver homogenate metabolizing system (10% in standard co-factors)
Test concentrations with justification for top dose:
0, 0.5, 1.5, 5, 15, 50, 150, 500, 1500, and 5000 µg/plate
Vehicle:
- Vehicle(s)/solvent(s) used: dimethyl formamide
- Justification for choice of solvent/vehicle: no data
Controlsopen allclose all
Negative controls:
yes
Remarks:
untreated
Solvent controls:
yes
Remarks:
DMF
True negative controls:
no
Positive controls:
yes
Positive control substance:
N-ethyl-N-nitro-N-nitrosoguanidine
Remarks:
Without S9 for TA100 at 3 µg/plate
Negative controls:
yes
Remarks:
untreated
Solvent controls:
yes
Remarks:
DMF
True negative controls:
no
Positive controls:
yes
Positive control substance:
mitomycin C
Remarks:
without S9 for TA102 at 0.5 µg/plate
Negative controls:
yes
Remarks:
untreated
Solvent controls:
yes
Remarks:
DMF
True negative controls:
no
Positive controls:
yes
Positive control substance:
4-nitroquinoline-N-oxide
Remarks:
without S9 for TA98 at 0.2 µg/plate
Negative controls:
yes
Remarks:
untreated
Solvent controls:
yes
Remarks:
DMF
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: 2-Aminoanthracene (2AA)
Remarks:
With S9 for TA100 at 1 µg/plate
Negative controls:
yes
Remarks:
untreated
Solvent controls:
yes
Remarks:
DMF
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: 1,8-Dihydroxyanthraquinone (DAN)
Remarks:
with S9 for TA102 at 10 µg/plate
Negative controls:
yes
Remarks:
untreated
Solvent controls:
yes
Remarks:
DMF
True negative controls:
no
Positive controls:
yes
Positive control substance:
benzo(a)pyrene
Remarks:
with S9 for TA98 at 5 µg/plate
Details on test system and conditions:
METHOD OF APPLICATION:
- in agar (plate incorporation)

Measured aliquots (0.1 ml) of one of the bacterial cultures were dispensed into sets of test tubes followed by 2.0 ml of molten, trace histidine supplemented, top agar, 0.1 ml of the test material formulation, vehicle or positive control and either 0.5 ml of S9-mix of phosphate buffer. The contents of each test tub
e were mixed and equally distributed onto the surface of Vogel-Bonner Minimal agar plates (one tube per plate). This procedure was repeated, in triplicate, for each bacterial strain and for each concentration of the test material both with and without S9-mix.

DURATION
- Exposure duration: 3 days
- Selection time: 3 days, simultaneously with exposure

SELECTION AGENT: histidine

NUMBER OF REPLICATIONS: triplicates

DETERMINATION OF CYTOTOXICITY
- Method: reduction in the growth of the bacterial background lawn

OTHER:
Prior to use, the master strains were checked for characteristics, viability and spontaneous reversion rate.
Evaluation criteria:
no data
Statistics:
no data

Results and discussion

Test results
Species / strain:
other: TA98, TA100, and TA102
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity:
no, but tested up to limit concentrations
Remarks:
based on maximum recommended dose of the guideline
Vehicle controls valid:
yes
Negative controls valid:
yes
Positive controls valid:
yes
Remarks on result:
other: all strains/cell types tested
Additional information on results:
TEST-SPECIFIC CONFOUNDING FACTORS
- Evaporation from medium: no data
- Water solubility: no data
- Precipitation: A cream-coloured, flaky precipitate was observed at and above 1500 µg/plate, but this did not prevent the scoring of revertant colonies.

RANGE-FINDING/SCREENING STUDIES: No data were provided on a range-finding test.

COMPARISON WITH HISTORICAL CONTROL DATA:
The vehicle (DMSO) control plates gave counts of revertants colonies witin the normal range. All the positive control chemicals used in the test induced marked increases in the frequency of revertant colonies, both with and without metabolic activation. Thus the sensitivity of the assay and the efficacity of the S9-mix were validated. Results for the negative controls (spontaneous mutation rates) were considered to be acceptable.

ADDITIONAL INFORMATION ON CYTOTOXICITY:
The test substance caused no visible reduction in the growth of the bacterial background lawn at any dose level.

Applicant's summary and conclusion

Conclusions:
Interpretation of results:
negative with metabolic activation
ambiguous without metabolic activation

The test substance was evaluated for mutagenic potential using the "Ames Test" in S. typhimurium strains TA100, TA98 and TA102 in the absence and presence of metabolic activation. Based on the results and the expert statements, the test substance was considered to be non-mutagenic under the conditions of the study.