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Toxicological information

Genetic toxicity: in vitro

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Administrative data

Endpoint:
in vitro DNA damage and/or repair study
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1995
Report date:
1995

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 482 (Genetic Toxicology: DNA Damage and Repair, Unscheduled DNA Synthesis in Mammalian Cells In Vitro)
GLP compliance:
yes
Type of assay:
other: Damage and Repair, Unscheduled DNA Synthesis in mammalian cells in vitro

Test material

Constituent 1
Chemical structure
Reference substance name:
Butanone oxime
EC Number:
202-496-6
EC Name:
Butanone oxime
Cas Number:
96-29-7
Molecular formula:
C4H9NO
IUPAC Name:
(NE)-N-butan-2-ylidenehydroxylamine
Test material form:
liquid

Method

Species / strain
Species / strain / cell type:
hepatocytes: male Fischer F344 rats
Test concentrations with justification for top dose:
1500, 500, 150, 50 and 15 pg/ml
Vehicle / solvent:
- Vehicle: water
- Justification for choice of solvent/vehicle:based on a solubility and stability determination of the test article and compatibility with the target cells
Controls
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
7,12-dimethylbenzanthracene
Details on test system and experimental conditions:
- Exposure duration: 18-20 hours


NUMBER OF REPLICATIONS: 3

NUMBER OF CELLS EVALUATED: 150 cells total (50 per replicate)

DETERMINATION OF CYTOTOXICITY
- Method: other: LDH determinations of media

OTHER: nuclear grains were counted in fifty cells in random areas on each of three coverslips for a total of 150 cells per treatment. The net nuclear counts were determined by counting three nucleus-sized areas adjacent to each nucleus and subtracting the average cytoplasmic count from the nuclear count. Replicative synthesis was identified by nuclei completely blackened with grains and such cells were not counted. Nuclei exhibiting toxic effects of treatment, such as dark or uneven staining, disrupted membranes, or irregular shape, were not counted
Evaluation criteria:
If the mean net nuclear count was increased by at least five counts over the vehicle control, the results for a particular dose level were considered significant. A test article was judged positive if it induced a dose-related response and at least one dose produced a significant increase in the average net nuclear grains when compared to that of the vehicle control. In the absence of a dose response, a test article which showed a significant increase in the mean net nuclear grain count in at least two successive doses was considered positive.

Results and discussion

Test results
Species / strain:
hepatocytes: male F344 rats
Metabolic activation:
not applicable
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
5000 and 1500 pg/ml
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid

Applicant's summary and conclusion

Conclusions:
The results of the UDS assay indicate that under the test conditions, the test article did not cause a significant increase in the unscheduled DNA synthesis as measured by the mean number of net nuclear grain counts (i.e., an increase of at least 5 counts over the vehicle control), at any dose level. In this study the positive control, DMBA, induced a significant increase in the mean number of net nuclear grain counts over that in the vehicle control. All criteria for a valid test were met. Therefore, the test article is considered to be negative in this study