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Toxicological information

Repeated dose toxicity: oral

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Administrative data

Endpoint:
repeated dose toxicity: oral
Remarks:
other: 14-Day Range Finder
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: The study was conducted according to O.E.C.D. Testing Guideline 422 following the GLP regulations including analytical verification of test substance concentration, homogeneity and stability.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1994
Report date:
1995

Materials and methods

Principles of method if other than guideline:
14-day range finder for a rat developmental toxicity study.
GLP compliance:
yes
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
Vinyl 2-ethylhexanoate
EC Number:
202-297-4
EC Name:
Vinyl 2-ethylhexanoate
Cas Number:
94-04-2
Molecular formula:
C10H18O2
IUPAC Name:
ethenyl 2-ethylhexanoate
Details on test material:
The test substance was a transparent colorless liquid and was stored in a glass bottle at room temperature. The concentration was determined analytically to be 99.8%.

Test animals

Species:
rat
Strain:
Fischer 344
Sex:
male/female
Details on test animals or test system and environmental conditions:
The animals were approximately 35 days old upon arrival at the test facility. Serology testing was performed 2 weeks after reciept using animals not chosen for the study. Animals were identified by cage tags and tail tatooing. The animals were housed individually in stainless steel wire mesh cages during the study. The animals were housed in polycarbonate cage during the FOB evaluations. Animals were on a 12 hour light-dark cycle at 66-77 deg F and 40-70% humidity. Food and water was available ad libitum and analysis was provided in the raw data.

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
corn oil
Details on oral exposure:
Dosing solutions were prepared by dilution of the test substance with corn oil in volumetric flasks. The dose was prepared fresh each day. The oral gavage was give using an 18-gauge stainless steel animal feeding needle connected to an automatic dispenser/diluter. Each animal was given 4.0 ml/kg/day regarless of dose.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
The concentrations of vinyl 2-ethylhexanoate in corn oil were analysed using a gas chromatograph. The calibration curves and concentration verifications (Day 7 and Day 14) were provided in the study.
Duration of treatment / exposure:
5 days a week for 2 weeks
Frequency of treatment:
1 per day
Doses / concentrationsopen allclose all
Remarks:
Doses / Concentrations:
0 mg/kg/day
Basis:
actual ingested
Remarks:
Doses / Concentrations:
50 mg/kg/day
Basis:
actual ingested
Remarks:
Doses / Concentrations:
200 mg/kg/day
Basis:
actual ingested
Remarks:
Doses / Concentrations:
1000 mg/kg/day
Basis:
actual ingested
Remarks:
Doses / Concentrations:
2000 mg/kg/day
Basis:
actual ingested
No. of animals per sex per dose:
6
Control animals:
yes, concurrent vehicle

Examinations

Observations and examinations performed and frequency:
Observations for mortality and overt signs were made twice daily. A detailed clinical observation was made at dosing and after the first dosing hourly for five hours.Body weight was recorded on Day 1, 4, 8 and 15. Food consuption was monitered during the study. The neurobehavioral function of all animals was evaluated (FOB) on days 12, 13 and 14. Blood was drawn prior to final sacrifice for hematology.
Sacrifice and pathology:
Necropsy - Non-Perfused Rats:
All animals that were found dead during the dosing period, and 3 rats/group/sex from the animals sacrificed on Day 15 were subject to necropsy and tissues were fixed by standard immersion techniques. Sacrificed rats not selected for perfusion were anesthetized with halothane and were euthanized by severing their brachial vessels to permit exsanguination. Body weight were obtained to allow expression of relative organ weights. A complete necropsy was performed on all animals. The liver, kidneys, adrenals, spleen, ovaries, testes and brain were weighed for all non-perfused animals.
Histopathology: Non - Perfused Rats
Microscopic examinations were performed on the brains, sciatic nerves, tibial nerves, and gross lesions for all nonperfused rats. The liver, kidneys, testes and gross lesions were examined for the 0, 1000, and 2000 mg/kg/day dose levels. All tissues to be examined were parafin embeded, sectioned at 5 microns and stained with hematoxylin and eosin. Lesions were graded into five degrees.
Necropsy - Perfused Rats:
At termination 3 rats/group/sex from the animals sacrificed on Day 15 from groups 0, 50, 200, 1000 and the survivors from the 2000 mg/kg/day and the 2 male rats sacrificed on Day 3 in a moribund state were selected for perfusion. These animals were anesthetized with an i.p. injection of a mixture of Euthanasia-6 Solution and heparin. After a deep plane of surgical anesthezia had been induced the chest cavity was opened, a cannula was placed into the left ventricular chamber for perfusion with 10% phosphate bufered formalin. An abbreviated necrpsy was performed and tissues were removed and immersion fixed.
Histopathology: Perfused Rats
Microscopic examinations were performed on the removed tissues of perfused rats. The liver, kidneys, testes and gross lesions were examined for the 0, 1000, and 2000 mg/kg/day dose levels. The sections of brain, spinal cord, Gasserian ganglia, nerve roots, and dorsal root ganglia were embedded in paraffin. 5 microns sections were stained with hematoxylin, eosin, luxol fast blue, and the Bielschowsky's techniques. The peripheral nerves were embedded in glycol wethacrylate, sectioned at 2 microns and stained with hematoxylin, eosin, toluidine blue, and the Bielschowsky's techniques.
Statistics:
The data for quantitative continuous variables were intercompared for the 4 treatment groups and the control group by use of the Levene's test for equal variances, analysis of variance (ANOVA), and t-tests. The t-tests were used when the F value from the AVOVA was significant. When Levene's test indicated similar variances, and the ANOVA was significant, a pooled t-test was used for pairwise comparisons. When Levene's test indicated heterogeneous variances, all groups were compared by ANOVA for unequal variances followed, when necessary, by a seperate variance t-test for paiwise comparisons.
Nonparametric data were statistically evaluated using the Kruskal-Wallis test followed by the Mann-Whitney U-test. Incidence data were compared using Fisher's Exact test. Incidence data for select FOB endpoints with ordered severity scores were analyzed forgroup differences using Gamma, Kendall's Tau-B, Stuart's Tau-C, Somer's D measures of association. For all statistical tests, the probability value of <0.05 (two-tailed) was used as the critical level of significance.

Results and discussion

Results of examinations

Clinical signs:
effects observed, treatment-related
Mortality:
mortality observed, treatment-related
Body weight and weight changes:
effects observed, treatment-related
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Food efficiency:
no effects observed
Water consumption and compound intake (if drinking water study):
no effects observed
Ophthalmological findings:
not examined
Haematological findings:
effects observed, treatment-related
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
no effects observed
Behaviour (functional findings):
effects observed, treatment-related
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Gross pathological findings:
effects observed, treatment-related
Histopathological findings: non-neoplastic:
not examined
Histopathological findings: neoplastic:
not examined
Details on results:
All effects obsewrved occured at the 2000 mg/kg/day level with the exception of the necropsy and hematology findings, which had effecs at the 1000 mg/kg/day level.

Effect levels

Dose descriptor:
NOAEL
Effect level:
200 mg/kg bw/day (actual dose received)
Sex:
male/female
Basis for effect level:
clinical signs
mortality

Target system / organ toxicity

Critical effects observed:
not specified

Applicant's summary and conclusion

Conclusions:
The NOAEL for this study would be 200 mg/kg/day, based on the pathology and hematology observed in the 1000 mg/kg/day dose to rats.
Executive summary:

Administration of vinyl 2 -ethylhexanoate to rats resulted in mortality in 5 of 6 males and 3 of 6 females following the second daily dose of 2000 mg/kg/day. Due to this mortality, surviving animals from this dose group were not treated for the remainder of the study. Clinical signs of toxicity in these surviving animals, as well as decreased food consumption and body weight, resolved following the termination of dosing but microscopic lesions of the central nervous system were observed in these animals but not in animals that died during the study. Repeated administration of 1000 mg/kg/day of vinyl 2 -ethylhexanoate resulted in slight, reversable changes in the function of the nervous system. A slight, non-statistically significant increase, approximately 20%, in landing leg splay were observed in female animals from the 1000 mg/kg/day dose group, however, this questionable change was not associated with other alterations in neuromotor function or microscopic lesions of the central nervous system and could not be clearly attributed to treatment with the test substance. Equivocal hematology changes in females an increased liver and kidney weights of males were observed in the 200 mg/kg/day dose group. The no-observed-adverse-effect level of vinyl 2 -ethylhexanoate under the conditions of this study was considered to be 200 mg/kg/day.