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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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2003
Report date:
2003

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay

Test material

Constituent 1
Test material form:
solid: bulk
Details on test material:
Please refer to "Confidential details on test material".

Method

Target gene:
S. typhimurium
histidine operon

E. coli
tryptophan operon
Species / strainopen allclose all
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102
Species / strain / cell type:
E. coli WP2 uvr A
Metabolic activation:
with and without
Metabolic activation system:
S9 mix, prepared from a liver microsomal fraction (S9 fraction) of rats induced with Aroclor 1254.
Test concentrations with justification for top dose:
0; 62.5, 125, 250, 500 and 1000 µg/plate
Vehicle / solvent:
- Vehicle used: DMSO
- Justification for choice of solvent/vehicle: good solubility
Controls
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
4-nitroquinoline-N-oxide
9-aminoacridine
2-nitrofluorene
sodium azide
mitomycin C
other: 2-anthramine
Details on test system and experimental conditions:

METHOD OF APPLICATION: The preliminary test, both experiments without S9 mix and the first experiment with S9 mix were performed according to the direct plate incorporation method. The second experiment with S9 mix was performed according to the preincubation method.

DURATION:
- Preincubation period: 60 min
- Exposure duration: 48 - 72 hours

NUMBER OF REPLICATIONS: 3 test plates per dose or per control

DETERMINATION OF CYTOTOXICITY
- Method: other: The evaluation of the toxicity was performed on the basis of the observation of the decrease in the number of revertant colonies and/or a thinning of the bacterial lawn.
Evaluation criteria:
This study was considered valid if the following criteria are fully met:
Acceptance
- the number of revertants in the vehicle controls is consistent with the historical data of the testing facility,
- the number of revertants in the positive controls is higher than that of the vehicle controls and is consistent with the historical data of the testing facility.

Evaluation
A reproducible 2-fold increase (for the TA 98, TA 100, TA 102 and WP2 uvrA strains) or 3-fold increase (for the TA 1535 and TA 1537 strains) in the number of revertants compared with the vehicle controls, in any strain at any dose-level and/or evidence of a dose-relationship was considered as a positive result. Reference to historical data, or other considerations of biological relevance were also taken into account in the evaluation of the data obtained.

Results and discussion

Test results
Species / strain:
other: S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102 ; E.coli WP2 uvrA
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity, but tested up to precipitating concentrations
Remarks:
> 500 μg/plate
Vehicle controls validity:
valid
Untreated negative controls validity:
not examined
Positive controls validity:
valid
Additional information on results:
TEST-SPECIFIC CONFOUNDING FACTORS

- Water solubility: no
- Precipitation: yes

RANGE-FINDING/SCREENING STUDY
Cytotoxicity was tested in 4 strains at 10, 100, 500, 1000, 2500 and 5000 µg/plate with and without S9-mix. No noteworthy toxicity was noted. A moderate to marked precipitate was observed at 500 µg/plate and above.
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.

Any other information on results incl. tables

The test item did not induce any significant increase in the number of revertants, both with or without S9 mix, in any of the 6 strains.

The number of revertants for the vehicle and positive controls was as specified in the acceptance criteria. The study was therefore considered valid.

Applicant's summary and conclusion