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Toxicological information

Genetic toxicity: in vivo

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Administrative data

Endpoint:
in vivo mammalian germ cell study: cytogenicity / chromosome aberration
Remarks:
Type of genotoxicity: chromosome aberration
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
other: Significant methodological deficiencies. Only males examined. Low number of cells examined (50 metaphases instead of 100 per animal; mitotic index in 100 cells instead of 1000 cells).

Data source

Referenceopen allclose all

Title:
No information
Author:
EPA
Year:
1980
Bibliographic source:
Document No. 86-87000603, Microfiche No. OTS0515130
Report Date:
1980
Reference Type:
publication
Title:
Unnamed
Year:
1983
Report Date:
1983

Materials and methods

Principles of method if other than guideline:
cytogenetics assay was performed according to a modification of the procedures described by Kilian et al [1977]
GLP compliance:
not specified
Type of assay:
chromosome aberration assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Analytical purity: >99.7%

Test animals

Species:
rat
Strain:
Fischer 344
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Breeding Laboratories, Kingston, NY, USA
- Weight at study initiation: 150-190 g
- Assigned to test groups randomly: yes, randomly assigned to five groups of five animals each.
- Housing: in an American Association for the Accreditation of Laboratory Animal Care (AAALAC)-accredited facility. Rats were housed three to four per cage during the quarantine period and one per cage during treatment. Hardwood chips were used as bedding
- Diet: certified laboratory chow, ad libitum
- Water: ad libitum
- Acclimation period: 10-14 days prior to testing

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 23 +/- 2
- Humidity (%): 50 +/- 20
- Photoperiod (hrs dark / hrs light): 12-hr light/dark cycle

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
- Vehicle(s)/solvent(s) used: corn oil
- Concentration of test material in vehicle: 5 ml/kg/day
Duration of treatment / exposure:
5 days
Frequency of treatment:
daily
Post exposure period:
6 hours after the last dose rats were sacrificed
Doses / concentrations
Remarks:
Doses / Concentrations:
0.02, 0.07, 0.2 ml/kg day
Basis:

No. of animals per sex per dose:
5 males per dose
Control animals:
yes, concurrent vehicle
Positive control(s):
triethylenemelamine
- Doses: 0.5 ml/kg
- single intraperitoneal (IP) injection one day prior sacrifice

Examinations

Details of tissue and slide preparation:
CRITERIA FOR DOSE SELECTION:
The dose levels, the highest of which represented approximately one-tenth of the five-day LD50, were based on a preliminary five-day dose-finding study for each test material.

TREATMENT AND SAMPLING TIMES ( in addition to information in specific fields):
The rats were sacrificed by carbon dioxide asphyxiation six hr after the last dose.

DETAILS OF SLIDE PREPARATION:
The femurs were removed, and the bone marrow flushed into Hanks' balanced salt solution. After centrifugation at 600-800g for 8-10 min, the cells were treated with 0.075 M KCl for 20-30 min at 37°C. The cells were again centrifuged and washed twice with 5 ml of Carnoy's fixative. The cells were resuspended in 5 ml of Carnoy's fixative and allowed to stand overnight at 4°C. The cells were then centrifuged and resuspended to opalescence in fresh Carnoy's fixative. Two to five slides were prepared from each animal. Slides were stained with Giemsa and permanently mounted.

METHOD OF ANALYSIS:
A minimum of 50 metaphase spreads from each animal was scored for chromatid and chromosomal gaps, breaks, and fragmentation, structural rearrangements, and ploidy [Cohen and Hirschorn, 1971; Kilian et al, 1977; Legator et al, 1973].
Spreads were selected for evaluation by systematic scanning of slides. Only cells which appeared intact with the chromosomes spread symmetrically, with no other metaphase cells intruding into the vicinity, and which contained no less than 36 chromosomes, were scored. In addition, the mitotic index (mitosis/100 cells) was recorded for each test animal.

Results and discussion

Test results
Sex:
male

Any other information on results incl. tables

Of the 50 metaphase bone marrow cells examined from each animal, no significant 
increase in chromatid and chromosome breaks or structural rearrangements
was noted. The mitotic index was unaffected by 2-ethylhexanol.

Applicant's summary and conclusion

Conclusions:
According to the authors the dose levels tested did not induce detectable chromosomal aberrations after oral administration, or change the mitotic index. However, the number of cells examined is too low to comply with current test guidelines.