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Toxicological information

Genetic toxicity: in vivo

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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:
1991-08-14 to 1993-02-11
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Conduction and documentation of study very acceptable. Study report available.

Data source

Referenceopen allclose all

Reference Type:
study report
Title:
Unnamed
Year:
1993
Report Date:
1993
Reference Type:
publication
Title:
Unnamed
Year:
2000
Report Date:
2000

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
EPA OPPTS 870.5395 (In Vivo Mammalian Cytogenetics Tests: Erythrocyte Micronucleus Assay)
Deviations:
no
Principles of method if other than guideline:
5 Male and 5 female Swiss Webster mice per dose group were exposed to 2,4-pentanedione-vapour at concentra-tions of 0,100, 400 and 600 ppm by whole body exposure. The highest concentrations chosen was about 50 % below the LC50 values determined in acute inhalation toxicity studies with female rats. Bone marrows from 2,4-pentanedione-treated as well as aironly- control and positive control (triethylenemelamine, 30 mg/kg i.p.) animals were collected from femurs 24 hours after final exposure and examined for the formation of micronucleated poly-chromatic erythrocytes. The PCE.NCE ratio for a total of 1000 cells for each animal was calculated to provide an estimate of cytotoxicity. A minimum of 1000 PCE for each animal was scored for the presence of micronuclei unless the cytotoxicity of the test substance prevented this. All animals were observed individually for mortality and signs of toxicity. During exposure, observations were recorded on a group basis. Body weight data were collected for all ani-mals prior to the first exposure and immediately after the last exposure
GLP compliance:
yes
Type of assay:
micronucleus assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): 2,4-Pentanedione
- Physical state: liquid
- Stability under test conditions: stable

Test animals

Species:
mouse
Strain:
Swiss Webster
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Laboratories. (Portage, MI).
- Age at study initiation: 5 weeks
- Weight at study initiation: 17.7-21.1 g (female), 22.4 - 25.6 g (males)
- Assigned to test groups randomly: yes
- Fasting period before study: not reported
- Housing: individually
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period:1 week


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 65-77 °F
- Humidity (%): 40-70
- Air changes (per hr): approx. 13-14
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: 1991-08-25 To: 1991-08-30

Administration / exposure

Route of administration:
inhalation
Vehicle:
air
Details on exposure:
TYPE OF INHALATION EXPOSURE: whole body

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Wahmann Manufacturing Compnay, Timonium, MD, USA, stainless steel with glass window, rectangular, 4320 l
- System of generating particulates/aerosols: piston pump (G-6 FMI pump for the 100 and 400 ppm exposure chambers; G-20 FMI pump for the 600 ppm exposure chamber; Fluid Meteringr Inc., Oyster Bay NY)
- Temperature, humidity, pressure in air chamber:
- Air flow rate: 1000 l/min
- Air change rate: 13-14


TEST ATMOSPHERE
- Brief description of analytical method used: GC
Duration of treatment / exposure:
6hrs/day for 5 days
Frequency of treatment:
5 consecutive days
Post exposure period:
24 h
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 97, 405, 592 ppm
Basis:
analytical conc.
No. of animals per sex per dose:
5 animals
Control animals:
yes, concurrent vehicle
Positive control(s):
triethylenemelamine
- Route of administration: IP
- Doses / concentrations: 30 mg/kg

Examinations

Tissues and cell types examined:
Bone marrow
Details of tissue and slide preparation:
All animals were sacrificed by carbon dioxide asphyxiation 24 hour8 after the last exposure. Both femurs were removed from each animal and the bone marrow was aspirated with a sy-ringe into fetal bovine serum (PBS) Bone marrow cells were whole aspirated marrow sample. All but a small amount of the supernate was removed. The cell pellet was resuspensed gently and a drop of the bone marrow cell suspension was smeared on a microscope slide. Slides were stained with R-66 Giemsa- diluted in phospate buffer. Slides were coded with the randomly-assigned animal numbers and read without knowlegde of exposure group to prevent bias. Slides were identified by project number, animal number and sampling interval. The PCE:NCE ratio for a total of 1000 cells for each animals was calculated to provide an estimate of test substance cytotoxicity. A minimum of 1000 PCE each animal was scored for the presence of micronuclei unless the cytotoxicity of the test substance prevented this.
Evaluation criteria:
comparison mean percentage PCE with negative and positive control
Statistics:
Mann-Whitney U-test

Results and discussion

Test results
Sex:
male/female
Genotoxicity:
negative
Toxicity:
yes
Remarks:
mortality, hypoactivity, prostration, urogenital wetness, gasping, slow respiration and blepharospasm in female high dose group
Vehicle controls validity:
valid
Negative controls validity:
not specified
Positive controls validity:
valid
Additional information on results:
RESULTS OF DEFINITIVE STUDY
- Ratio of PCE/NCE (for Micronucleus assay): The number of micronucleated PCE/1000 PCE was between 0 and 6/animal in both the vehicle control and the 2,4-pentanedione-exposed mice. The mean percentage of micronucleated PCE was 0.34 for the air-only-exposed males and 0.14 for the air-only-exposed females. Among TS –exposed males, the mean percentage of miconucleated PCE ranged from a low of 0.20 at 400 and 600 ppm to a high of 0.28 at 100 ppm. Among TS-exposed females, the mean percentage of micronucleated PCE ranged from a low of 0.10 at 100 ppm to a high of 0.22 at 400 ppm.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): negative
2,4-Pentanedione did not produce significant or dose-related increases in the frequency of micronucleated polychromatic erythrocytes in
the bone marrow of Swiss-Webster mice assessed at 24 hrs after whole body exposure to 2,4-pentanedione vapor 6 hours each day for 5
consecutive days.
Executive summary:

5 Male and 5 female Swiss Webster mice per dose group were exposed to 2,4-pentanedione-vapour at concentrations of 0,100, 400 and 600 ppm by whole body exposure. The highest concentrations chosen was about 50 % below the LC50 values determined in acute inhalation toxicity studies with female rats. Bone marrows from 2,4-pentanedione-treated as well as aironly- control and positive control (triethylenemelamine, 30 mg/kg i.p.) animals were collected from femurs 24 hours after final exposure and examined for the formation of micronucleated polychromatic erythrocytes. The PCE.NCE ratio for a total of 1000 cells for each animal was calculated to provide an estimate of cytotoxicity. A minimum of 1000 PCE for each animal was scored for the presence of micronuclei unless the cytotoxicity of the test substance prevented this. All animals were observed individually for mortality and signs of toxicity. During exposure, observations were recorded on a group basis. Body weight data were collected for all animals prior to the first exposure and immediately after the last exposure.

Chamber concentrations were analyzed approximately once each hour during the 6 h exposure by gas chromatography. The mean analysed chamber concentrations of 2,4 -pentanedione were 97, 405, and 592 ppm for target concentrations of 100, 400, and 600 ppm, respectively.

No noteworthy clinical signs in any of the 2,4-pentanedione treated male or female mice were observed at 0, 100 and 400 ppm. Three female mice in the 600 ppm exposure group died during the study. Substance related effects were evident as hypoactivity, prostration, urogenital wetness, gasping, slow respiration and blepharospasm in on or more of these females. No significant effects on weight changes were noted. There were no significant differences in the PCE to NCE ratios between 2,4-pentanedione-exposed and control animals. The number of micronucleated PCE/1000 PCE was between 0 and 6/animal in both the vehicle control and the 2,4-pentanedione-exposed mice. The mean percentage of micronucleated PCE was 0.34 for the air-only-exposed males and 0.14 for the air-only-exposed females. Among TS –exposed males, the mean percentage of miconucleated PCE ranged from a low of 0.20 at 400 and 600 ppm to a high of 0.28 at 100 ppm. Among TS-exposed females, the mean percentage of micronucleated PCE ranged from a low of 0.10 at 100 ppm to a high of 0.22 at 400 ppm.

Trietylenemelamine, used as a positive control substance for this study, produced highly significant increase in numbers of micronuclei in both sexes. Numbers of micronuclei in the vehicle control animals were in a low and acceptable range for this test system.

In conclusions 2,4-pentanedione did not produce significant or dose-related increases in the frequency of micronucleated polychromatic erythrocytes in the bone marrow of Swiss-Webster mice assessed at 24 hrs after whole body exposure to 2,4-pentanedione vapor 6 hours each day for 5 consecutive days. Therefore, the TS was not considered to be an inducer of micronuclie under the conditions of this in vivo assay.