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Toxicological information

Genetic toxicity: in vitro

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Administrative data

Endpoint:
in vitro gene mutation study in mammalian cells
Remarks:
Type of genotoxicity: gene mutation
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
1984
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Well documented, according to accepted guidelines, for read-across substance

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1984
Report Date:
1984

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 476 (In Vitro Mammalian Cell Gene Mutation Test)
Deviations:
no
GLP compliance:
no
Type of assay:
mammalian cell gene mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Methyl ethyl ketone
- Physical state: Clear liquid
- Lot/batch No.: 5-82
- Storage condition of test material: Room temperature with ventilation

Method

Species / strain
Species / strain / cell type:
mouse lymphoma L5178Y cells
Additional strain / cell type characteristics:
not applicable
Metabolic activation:
with and without
Metabolic activation system:
Aroclor-induced rat liver microsomes (S9)
Test concentrations with justification for top dose:
Preliminary toxicity test: 0.001, 0.01, 0.1, 1.0, 10, or 100 µL/mL
Mutagenesis test (-S9): 0.89, 1.2, 1.6, 2.1, 2.8, 3.8, 5.0, 6.7, 8.9, 12.0, 16, or 21 µL/mL
Mutagenesis test (+S9): 0.67, 0.89, 1.2, 1.6, 2.1, 2.8, 3.8, 5.0, 6.7, 8.9, 12, or 16 µL/mL
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: DMSO
Controls
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
Remarks:
DMSO
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: Ethyl methanesulfonate and 7,12-dimethylbenz[a]anthracene
Details on test system and experimental conditions:
A preliminary toxicity test with and without S9 activation was conducted. The test article was solubilized and diluted for testing at 100, 10, 1.0, 0.1, 0.01 and 0.001 µL/mL for 4 hours. Test article toxicity was determined by comparing the cell population growth at each dose level with that of the solvent controls. Cell population density was determined 24 and 48 hours after the initial exposure to the test article.

Based on the data derived from the toxicity test, the test article was prepared so that the highest concentration was 100% toxic. The test article was solubilized and 15 serial eighth log dilutions were carried out. This produced 16 dose levels decreasing approximately 100-fold from highest to lowest. The compound was tested with and without S9 activation. Two control tubes received solvent only and the positive controls were treated with EMS (1.0 and 0.5 µL/mL) and 7,12-DMBA (7.5 and 5.0 µg/mL). All tubes were incubated for 4 hours at 37°C. The preparation and addition of the test article was carried out under amber lighting and the cells were incubated in the dark during the 4-hour exposure period.

After the incubation period, plates were scored for the total number of colonies per plate. Three counts per plate were made on an automatic colony counter, and the median count was recorded. The mutation frequency also was determined.
Evaluation criteria:
The following criteria were used as guidelines in judging the significance of the activity of a test article in this system. In evaluating the results, it is considered that increases in mutant frequencies, which occur only at highly toxic concentrations, may be due to epigenetic events. Unfortunately, it is impossible to formulate criteria which would apply to all types of data which may be generated and therefore the scientist’s evaluation must be the final endpoint.

Positive:- if there is a positive dose response and one or more of the three highest doses exhibit a mutant frequency which is two-fold greater than the background level.
Equivocal:- if there is no dose response but any one or more doses exhibit a two-fold increase in mutant frequency over background.
Negative:- if there is no dose response and none of the test cultures exhibit mutant frequencies which are two-fold greater than background.
Statistics:
Not required (mutation frequency is calculated).

Results and discussion

Test results
Species / strain:
mouse lymphoma L5178Y cells
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
At 100 µL/mL
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
negative with metabolic activation
negative without metabolic activation