4-methylpentan-2-one

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1984

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

1984

Report date:

1984

Reference 2

Reference Type:

publication

Title:

Mutagenicity studies on ketone solvents: methyl ethyl ketone, methyl isobutyl ketone and isophorone

Author:

O'donoghue JL, Haworth SR, Curren RD, Kirby PE., Lawlor T et al.

Year:

1988

Bibliographic source:

Mutat. Res., 206, 149-161

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)

Deviations:

yes

Remarks:

- only one dose used instead of 3.

GLP compliance:

yes

Type of assay:

micronucleus assay

Test material

Test material information

Constituent 1

Reference substance name:

4-methylpentan-2-one

EC Number:

203-550-1

EC Name:

4-methylpentan-2-one

Cas Number:

108-10-1

Molecular formula:

C6H12O

IUPAC Name:

4-methylpentan-2-one

Details on test material:

- Name of test material (as cited in study report): Methyl Isobutyl Ketone
- Physical state: Clear, colourless liquid
- Analytical purity: 99.56%
- Stability under test conditions: Not reported
- Storage condition of test material: Not reported

Test animals

Species:

mouse

Strain:

CD-1

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratory
- Age at study initiation: 6-8 weeks
- Weight at study initiation: 29-37 g (males) and 22-27 g (females)
- Assigned to test groups randomly: yes, under following basis: computer-generated random number table
- Fasting period before study: Not reported
- Housing: housed up to six per cage in plastic autoclavable cages with wire lids. Hardwood chips were used for bedding.
- Diet (e.g. ad libitum): Animals had free access to a certified laboratory rodent chow which had been analyzed for environmental contaminants.
- Water (e.g. ad libitum): Water was provided ad libitum
- Acclimation period: Not reported


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 76 ± 6ºF (approximately 24 ºC)
- Humidity (%): 50 ± 20%
- Air changes (per hr): Not reported
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

intraperitoneal

Vehicle:

- Vehicle(s)/solvent(s) used: corn oil

Details on exposure:

The test article-vehicle mixture and the vehicle alone were administered by I.P. injection at a rate of 10 mL/kg body weight. The positive control, TEM, was injected IP at a dose level of 0.25 mg/kg. All mice in the experimental and control groups were weighed immediately prior to dose administration and the dose volume based on individual body weights. Animals were observed after dose administration for clinical signs of chemical effect.

Duration of treatment / exposure:

12, 24, or 48 hours (single exposure: animals killed at 12, 24, or 48 hours)

Frequency of treatment:

Single administration

Post exposure period:

12, 24, or 48 hours

Doses / concentrations

Remarks:

Doses / Concentrations:
0.73 mL/kg bw
Basis:

No. of animals per sex per dose:

5/sex/dose/time point

Control animals:

yes, concurrent vehicle

Positive control(s):

triethylenemelamine
- Route of administration: IP
- Doses / concentrations: 0.25 mg/kg

Examinations

Tissues and cell types examined:

Bone marrow cells from the femurs.

Details of tissue and slide preparation:

At the scheduled sacrifice time, five mice/sex were sacrificed by cervical dislocation. Immediately following sacrifice, the femurs were exposed, cut just above the knee, and the bone marrow was aspirated into a syringe containing FBS. The bone marrow cells were transferred to a capped centrifuge tube containing approximately 1 mL cold FBS. The bone marrow cells were pelleted by centrifugation at approximately 1000 rpm for five minutes and the supernatant was drawn off, leaving a small amount of serum with the remaining cell pellet. The cells were resuspended by aspiration with a capillary pipette and a small drop of bone marrow suspension was spread onto a clean glass slide. Two to four slides were prepared from each animal. The slides were aged overnight and stained with May-Gruenwald-Giemsa and permanently mounted.

Evaluation criteria:

1000 polychromatic erythrocytes were scored for the presence of micronuclei. The number of micronucleated normocytes in the field of 1000 polychromatic erythrocytes was also enumerated. The ratio of normochromatic to polychromatic erythrocytes was recorded as the proportion of polychromatic erythrocytes per total erythrocytes.

The ratio of normochromatic to polychromatic erythrocytes is presented for each animal and treatment group as the proportion of polychromatic erythrocytes per total erythrocytes. The incidence of micronuleated polychromatic erythrocytes per 1000 polychromatic erythrocytes is presented for each animal and treatment group. An analysis of variance was used to compare the incidence of micronucleated polychromatic erythrocytes of the treatment group and solvent control groups.

The incidence of micronucleated erythrocytes per 1000 polychromatic erythrocytes must not exceed 0.5% in the negative (vehicle) control. The incidence of micronucleated polychromatic erythrocytes in the positive control group must be at least twice that of the negative control and significantly increased (p~0.05) relative to the negative control using t-test statistics.

Statistics:

The test article is considered to induce a positive response if a treatment-related increase (p<0.05, one-way ANOVA, Duncan’s multiple range test) in micronucleated polychromatic erythrocytes is observed relative to the vehicle control. All data, including reproducibility, was evaluated and a final judgment made on sound scientific basis.

Results and discussion

Test results

Sex:

male/female

Genotoxicity:

negative

Toxicity:

yes

Remarks:

2/18 male and 4/18 female mice died prior to scheduled sacrifice. Test article treated animals appeared heavily sedated immediately following administration (no other clinical signs of toxicity were observed).

Vehicle controls validity:

valid

Negative controls validity:

not applicable

Positive controls validity:

valid

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information): negative

Executive summary:

In a non-GLP micronucleus assay (equivalent to OECD guideline 474), MIBK was administered via intraperitoneal (IP) injection to male and female CD-1 mice at a dose of 0.73 mL/kg body weight.  Corn oil was used as the vehicle and triethylenemelamine was administered via the IP route as the positive control compound. Mice were sacrificed at 12, 24, or 48 hours following injection of test article or control (5 mice/sex/time point). Two male mice and 4 female mice died following test article administration and animals receiving MIBK appeared heavily sedated. No other clinical signs of toxicity were observed and no statistically significant increases in the number of micronucleated polychromatic erythrocytes were noted at any time point. Injection of the positive control caused the anticipated increase in micronucleated polychromatic erythrocytes. The use of only 1 dose level instead of the recommended 3 rendered this study reliable with restrictions.