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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:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Study period:
1989-09-20 to 1989-10-31
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Study conducted with a structural analogous read-across substance (free acid of the registered substance) in compliance to GLP and similar but not in accordance with current guidelines (recommended strain E.coli WPS or TA102 not included). Please refer to IUCLID section 13 for read-across justification.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1989
Report Date:
1989

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
yes
Remarks:
recommended strain E.coli WPS or TA102 not included
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

Method

Species / strainopen allclose all
Species / strain / cell type:
S. typhimurium TA 1538
Details on mammalian cell type (if applicable):
- Properly maintained: yes
Additional strain / cell type characteristics:
not specified
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Details on mammalian cell type (if applicable):
- Properly maintained: yes
Additional strain / cell type characteristics:
not specified
Metabolic activation:
with and without
Metabolic activation system:
S 9 mix ( obtained from Aroclor induced rat liver)
Test concentrations with justification for top dose:
333, 557, 1000, 3330, 6670, 10000 µg/plate
Vehicle / solvent:
- Vehicle used: DMSO, purity > 99 %
- Justification for choice of solvent/vehicle: Solubility
Controls
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Remarks:
with metabolic activation: TA98 and TA1538: 2-nitrofluorene, TA100 and TA 1535: sodium azide, TA1537 ICR-191; without metabolic activation 2-aminoanthracene
Remarks:
with metabolic activation: TA98 and TA1538: 2-nitrofluorene, TA100 a nd TA 1535: sodium azide, TA1537 ICR-191; without metabolic activation 2-aminoanthracene
Details on test system and experimental conditions:
A dose rangefinding study was performed using tester strain TA100 both in the presence and absence of microsomal enzymes. A minimum of ten dose levels of test article were tested (one plate per dose). The dose rangefinding study was performed using the same methodology as was used for themain assay. Cytotoxicity in this study is detectable as a decrease in the number of revertant colonies per plate and/or a thinning or disappearance of the bacterial background lawn. Routinely, the maximum dose selected to be tested in the mutagenicity assay should demonstrate cytotoxicity if possible.

Two independent test with three plate replications were performed on all strains with and without metabolic activation.

METHOD OF APPLICATION: Plate incorporation.

Duration
- Exposure duration: 48 h

NUMBER OF REPLICATIONS: 3


DETERMINATION OF CYTOTOXICITY
Colony formation

Evaluation criteria:
Tester Strains TA98 and TA100
For a test article to be considered positive, It must cause at least a 2-fold increase in the mean revertants per plate of at least one tester strain over the mean vehicle control value for that tester strain. This increase in the mean number of revertants per plate must be accompanied by a dose response to increasing concentrations of the test article.

Tester Strains .TA1535, TA1537 and TA1538
For a test article to be considered positive, it must cause at least a 3-fold increase in the mean revertants per plate of at least one tester strain over the mean vehicle control value for that tester strain. This increase in the mean number of revertants per plate must be accompanied by a dose response to increasing concentrations of the test article.
Statistics:
Not applicable

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:
cytotoxicity
Remarks:
slightly reduced background lawn in the highest concentration only in the absence of S 9 mix
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid
Additional information on results:
Dose range-findinq Study
Dose levels to be tested in the mutagenicity assay were selected based on the results of the dose range finding study conducted on the test article using tester strain TA100 in both the presence and absence of S9 (one plate per dose). Ten dose levels of test article, from 10000 to 10.0 µg per plate were tested. No cytotoxicity was observed in either the presence or absence of S9 as evidenced by no observed decrease in the number of revertants per plate. A slight reduction in the background lawn was observed in the absence of S9 at the highest dose level tested, however, the background lawn was evaluated as normal at all dose levels in the presence of S9.

Main Mutation Assay
The results of the dose rangefinding study were used to select 6 doses to be tested in the mutagenicity assay. The dose levels selected for the mutation assay ranged from 10000 to 333 µg per plate both in the presence and absence of S9.
In the Experiment, all data were acceptable and no positive increases in the number of histidine revertants per plate were observed with any of the tester strains either in the presence or absence of S9. All criteria for a valid study were met.
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.

Applicant's summary and conclusion