Registration Dossier

Toxicological information

Genetic toxicity: in vitro

Currently viewing:

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:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1999
Report Date:
1999

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
yes
Remarks:
The preliminary toxicity study was not performed in duplicates and can not count as a full repeat experiment. Seeing the results obtained, it is not considered to have an effect on the outcome of the study.
Principles of method if other than guideline:
The test system was exposed to the test article via the plate incorporation methodology originally described by Ames et al. (1975) and updates by Maron and Ames (1983).
GLP compliance:
yes
Remarks:
Wagner III VO and Caruthers SM
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Specific details on test material used for the study:
Lot No: 9709000929
Purity: 98%

Method

Target gene:
his
Species / strainopen allclose all
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Species / strain / cell type:
E. coli WP2 uvr A
Metabolic activation:
with and without
Metabolic activation system:
Aroclor-1254 induced rat liver S9 mix
Test concentrations with justification for top dose:
in the preliminary mutagenicity test: <= 5000 µg/plate methyl ionone
in the mutagenicity assay: 25 - 5000 µg/plate methyl ionone
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: DMSO
Controls
Untreated negative controls:
not specified
Negative solvent / vehicle controls:
not specified
True negative controls:
not specified
Positive controls:
not specified
Positive control substance:
not specified
Details on test system and experimental conditions:
METHOD OF APPLICATION: in agar (plate incorporation)

Results and discussion

Test resultsopen allclose all
Key result
Species / strain:
other: S. typhimurium TA98, TA100, TA1535, TA1537 and E.coli WP2
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
at the highest doses
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 98
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
not specified
Untreated negative controls validity:
not specified
Positive controls validity:
not specified
Species / strain:
S. typhimurium TA 100
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
≥1800μg per plate +/- S9
Vehicle controls validity:
not specified
Untreated negative controls validity:
not specified
Positive controls validity:
not specified
Species / strain:
S. typhimurium TA 1535
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
not specified
Untreated negative controls validity:
not specified
Positive controls validity:
not specified
Species / strain:
S. typhimurium TA 1537
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
≥1800μg per plate
Vehicle controls validity:
not specified
Untreated negative controls validity:
not specified
Positive controls validity:
not specified
Additional information on results:
TEST-SPECIFIC CONFOUNDING FACTORS
- Precipitation: no

Applicant's summary and conclusion

Conclusions:
A bacterial reverse mutation assay was conducted on Salmonella typhimurium strains TA98, TA100, TA1535 and TA1537, and Escherichia coli strain WP2uvrA in the presence and absence of S9 activation. Methyl ionone in dimethyl sulfoxide was tested at 25, 75, 200, 600, 1800, and 5000 ug/plate, and no positive response was observed. Methyl ionone was concluded to be negative in the bacterial reverse mutation assay.
Executive summary:

The test article, methyl ionone, was tested in the bacterial reverse mutation assay using S. typhimurium tester strains TA98, TA100, TA1535, TA1537 and E. coli tester strain WP2uvrA in the presence and absence of Aroclor-induced rat liver S9. The assay was performed in two phases, using the plate incorporation method. The first phase, the preliminary toxicity assay, was used to establish the dose range for the mutagenicitiy assay. The second phase, the mutagenicity assay, was used to evaluate the mutagenic potential of the test article. Dimethyl sulfoxide was selected as the solvent of choice based on solubility of the test article and compatibility with the target cells. The test article was soluble in dimethyl sulfoxide at a maximum concentration of approx. 500 mg/mL. In the preliminary assay, the maximum dose tested was 5000 ug/plate; this dose was achieved using a concentration of 100 mg/mL and a 50 uL plating aliquot. No precipitate was observed. Toxicity was observed at greater than or equal to 6667 ug/plate and at 5000 ug/plate with tester strain TA100 in the absence and presence of S9 activation, respectively. Toxicity was observed at greater than or 1000 ug/plate and at greater than or equal to 3333 ug/plate in the absence of S9 activation with tester strains TA1535 and TA1537, resp. Based on the findings of the toxicity assay, the maximum dose plated in the mutagenicity assay was 5000 ug/plate. In the mutagenicity assay, no positive response was observed. Under the conditions of this study, test article, methyl ionone, was concluded to be negative in the Bacterial Reverse Mutation Assay.