Pentan-3-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:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: no GLP compliance, pre-guideline study

Data source

Reference

Reference 1

Reference Type:

publication

Title:

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

Author:

O'Donoghue JL et al.

Year:

1988

Bibliographic source:

Mutation Research 206, 149-161

Reference 2

Reference Type:

study report

Title:

Unnamed

Report date:

1984

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)

GLP compliance:

no

Type of assay:

micronucleus assay

Test material

Test material information

Constituent 1

Reference substance name:

Butanone

EC Number:

201-159-0

EC Name:

Butanone

Cas Number:

78-93-3

Molecular formula:

C4H8O

IUPAC Name:

butan-2-one

Details on test material:

- Name of test material (as cited in study report): MEK
- supplied froim Celanese Corporation
- Analytical purity: 99.9 %
- test material was blanketed with nitrogen and stored at room temperature

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 Labs, Inc Kingston, N.Y.
- Age at study initiation: 6-8 weeks
- Weight at study initiation: males: 28-37 g, females: 22-26 g
- Assigned to test groups randomly: yes
- Housing: mice were-housed up to six per cage in plastic autoclavable cages with wire lids
- Diet (e.g. ad libitum): free access to a certified laboratory rodent chow which had been analyzed for environmental
contaminants
- Water (ad libitum): yes
- Acclimation period: quarantined for 10-14 days after receipt

ENVIRONMENTAL CONDITIONS
- Temperature: 74 °F
- Humidity: 50+-20 %
- Air changes (per hr):
- Photoperiod (hrs dark / hrs light): 12

Administration / exposure

Route of administration:

intraperitoneal

Vehicle:

- Vehicle solvent used: corn oil
- Amount of vehicle (if gavage or dermal): 10 mL of test item-corn oil mix / kg bw

Details on exposure:

- for the micronucleus assay, male and female mice were dosed by a single i.p. injection of MEK in corn oil at a dose level of 1.96 mL/kg.

Duration of treatment / exposure:

- animals were sacrficed 12, 24 or 48 hours after single dose exposure

Frequency of treatment:

- animals were given a single dose

Post exposure period:

- 12, 24 or 48 hours

Doses / concentrations

Remarks:

Doses / Concentrations:
1.96 mL/kg bw
Basis:
other: nominal dose given intraperitoneally

No. of animals per sex per dose:

- 5 per sex and time point of termination

Control animals:

yes, concurrent vehicle

Positive control(s):

- TEM (Triethylene melanime)
- Route of administration: intraperitoneal
- Concentration: 0.25 mg/kg bw

Examinations

Tissues and cell types examined:

- Bone marrow blood cells were prepared and polychromatic and normochromatic erythrocytes examined

Details of tissue and slide preparation:

DETAILS OF SLIDE PREPARATION:
- the femur was exposed and bone marrow aspirated into a syringe containing fetal calf serum
- cells were washed, centrifuged, resuspended and smears prepared
- May-Gruenwald-Giemsa stain was used to stain the bone marrow preparations
- 1000 polychromatic erythrocytes were scored on coded slides for the presence of micronuclei
- Micronucleated normocytes were also counted

Evaluation criteria:

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 test article is considered to induce a positive response if :
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, inclucling reproducibility, was evaluated and a final judgment made on scientific basis.

Statistics:

- an one-way analysis of variance and Duncan's multiple range test (P =< 0.05) was used to assess the statistical significance of any observed effects

Results and discussion

Test results

Sex:

male/female

Genotoxicity:

negative

Toxicity:

not specified

Vehicle controls validity:

valid

Negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

RESULTS OF RANGE-FINDING STUDY

For the acute dose-finding study, MEK was administered by i.p. injection to male and female CD-I mice at 12 dose levels: 8.0, 6.0,4.0, 3.2, 3.0,2.8, 2.6, 2.4, 2.2, 2.0, 1.0 and 0 mL/kg body weight which was administered in a total volume of 10 ml test article-vehicle mixture/kg body weight.
Using a probit analysis, the LD20 for males and females combined was calculated as 1.91 +- 0.2 mL test article/kg.

RESULTS OF DEFINITIVE STUDY

There were no significant differences in the ratio of polychromatic erythrocytes to normochromatic erythrocytes between treatment groups regardless of treatment or sacrifice time when analyzed by sex (p>0.05, ANOVA).
The number of micronucleated polychromatic erythrocytes per 1000 PCE was increased above the vehicle control 24 hours after administration of MEK, however the increase appears to be due to a low background and was not statistically significant when compared to all treatment and vehicle control groups of the same sex regardiess of sacrifice time (p>0.05, ANOVA) or when compared alone to all three vehicle controls of the same sex.
TEM induced a significant increase in micronucleated PCE in male and female mice (p<0.01, Student's t test).

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information): negative

Executive summary:

In a CD-1 mouse bone marrow micronucleus assay 5 animals/sex were treated by a single intraperitoneal injection with MEK (99.9 % a.i.) at a doses of 0 or 1.96 mL/kg bw MEK in corn oil. This dose was selected as the maximum tolerated dose (LD20 ) based upon a preliminary toxicity study. Bone marrow cells were harvested at 12, 24 or 48 hours post-treatment, stained and scored for the presence of micronucei.

There was no significant increase in the frequency of micronucleated polychromatic erythrocytes in bone marrow in males or female mice.

The positive control (TME) induced the appropriate response.