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Diss Factsheets

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:
22 August - 5 October 2007
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study (OECD 471) and in compliance with GLP.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2007
Report date:
2007

Materials and methods

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

Test material

Constituent 1
Reference substance name:
IN00078281
IUPAC Name:
IN00078281
Test material form:
solid: particulate/powder
Remarks:
migrated information: powder
Details on test material:
- Name of test material (as cited in study report): IN00078281
- Physical state: White powder
- Analytical purity: 100.1 % (per Certificate of Analysis)
- Purity test date: 22 August 2006
- Lot/batch No.: 7889-058-10
- Storage condition of test material: Room temperature in the dark with desiccant

Method

Species / strain
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2
Metabolic activation:
with and without
Metabolic activation system:
S 9 mix
Test concentrations with justification for top dose:
1.5, 5.0, 15, 150, 500, 1500 µg/plate
Vehicle / solvent:
- Vehicle used: DMSO
Controls
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
9-aminoacridine
2-nitrofluorene
sodium azide
methylmethanesulfonate
other: 2-aminoanthracene
Details on test system and experimental conditions:
METHOD OF APPLICATION: in agar (plate incorporation);

DURATION
- Exposure duration: 48 hours

NUMBER OF REPLICATIONS: 3 each per concentration level and control
Evaluation criteria:
For each replicate plating, the mean and standard deviation of the number of revertants per plate were calculated and are reported.
For the test article to be evaluated positive, it must cause a dose-related increase in the mean revertants per plate of at least one tester strain over a minimum of two increasing concentrations of test article.
Data sets for tester strains TA 1535 and TA 1537 were judged positive if the increase in mean revertants at the peak of the dose response was equal to or greater than 3.0-times the mean vehicle control value. Data sets for tester strains TA98, TA100 and VP2 uvrA were judged positive if the increase in mean revertants at the peak of the dose response was equal to or greater than 2.0-times the mean vehicle control value.
An equivocal response is a biologically relevant increase in a revertant count that partially meets the criteria for evaluation as positive. This could be a dose-responsive increase that does not achieve the respective threshold cited above or a non-dose responsive increase that is equal to or greater than the respective threshold cited. A response will be evaluated as negative, it it is neither positive nor equivocal.
Statistics:
not regarded as neccessary according to the OECD guidelines.

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:
no cytotoxicity, but tested up to precipitating 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'.

Any other information on results incl. tables

Solubility Test

Dimethyl sulfoxide (DMSO) was selected as the solvent of choice based on the solubility of the test article and compatibility with the target cells. The test article formed workable suspensions in dimethyl sulfoxide (DMSO) from approximately 200 to 350 mg/mL and a soluble and clear solution at approximately 150 mg/mL.

Sterility Results

No contaminant colonies were observed on the sterility plates for the vehicle control, the test article dilutions and the S9 and Sham mixes.

Initial Toxicity-Mutation Assay

The results of the initial toxicity-mutation assay are presented in Tables 1 through 10 and summarized in Table 21. These data were generated in Experiment B1. In the initial toxicity-mutation assay, the maximum dose tested was 5000 μg per plate; this dose was achieved using a concentration of 100 mg/mL and a 50 μL plating aliquot. The dose levels tested were 1.5, 5.0, 15, 50, 150, 500, 1500 and 5000 μg per plate. Precipitate was observed beginning at 500 μg per plate. No appreciable toxicity was observed. Based on the findings of the initial toxicity-mutation assay, the maximum dose plated in the confirmatory mutagenicity assay was 5000 μg per plate.

In Experiment B1 (Initial Toxicity-Mutation Assay), no positive mutagenic responses were observed with any of the tester strains in either the presence or absence of S9 activation.

Confirmatory Mutagenicity Assay

The results of the confirmatory mutagenicity assay are presented in Tables 11 through 20 and summarized in Table 22. These data were generated in Experiment B2. The dose levels tested were 15, 50, 150, 500, 1500 and 5000 μg per plate. Precipitate was observed beginning at 500 or 1500 μg per plate. No appreciable toxicity was observed.

In Experiment B2 (Confirmatory Mutagenicity Assay), no positive mutagenic responses were observed with any of the tester strains in either the presence or absence of S9 activation.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
negative

All criteria for a valid study were met as described in the protocol. The results of the IN00078281-Bacterial Reverse Mutation Assay indicate that, under the conditions of this study, IN00078281 did not cause a positive response in either the presence or absence of Aroclor induced rat liver S9.