Registration Dossier

Toxicological information

Repeated dose toxicity: oral

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Administrative data

Endpoint:
sub-chronic toxicity: oral
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study was conducted according to O.E.C.D. test guideline 408 with GLP compliance including test substance concentration and stability verification.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2014
Report Date:
2014

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity in Rodents)
Deviations:
yes
Remarks:
Additional special histopathology stains for kidney assessment and perfusion procedure for neurohistopathology.
GLP compliance:
yes
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Test material form:
other: Clear liquid at room temperature.
Details on test material:
As per IUCLID5 Sections 1.1. 1.2. and 1.4. for the read-across test substance Vinyl neononanoate, EC No. 259-160-7, CAS No. 54423-67-5, REACH Registration No. 01-2119433304-50-0000.

Test animals

Species:
rat
Strain:
Fischer 344/DuCrj
Sex:
male/female
Details on test animals and environmental conditions:
Fisher 344 rats (80 males and 80 females) were received in good health from Charles River Laboratories, Inc., Stone Ridge, NY. The animals were approximately 37 days old at receipt. All animals were housed for a 14 day acclimation period. All animals were housed individually in clean, stainless steel, wire mesh cages suspended above cage board. The cage board was changed at least 3 times per week.

The basal diet used in this study, PMI Nutrition International, LLC, Certified Rodent LabDiet® 5002 (meal), is a certified feed. Reverse osmosis treated (on site) drinking water, delivered by an automatic watering system, and the basal diet were provided ad libitum throughout the study, except during the period of fasting prior to clinical pathology blood collection when food, but not water, was withheld.

All animals were housed throughout acclimation and during the study in an environmentally controlled room. Actual mean daily temperature ranged from 70.2°F to 72.1°F (21.2°C to 22.3°C) and mean daily relative humidity ranged from 36.7% to 43.5% during the study. Fluorescent lighting provided illumination for a 12 hour light (0600 hours to 1800 hours)/12 hour dark photoperiod. Air handling units were set to provide a minimum of 10 fresh air changes per hour.

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
corn oil
Details on oral exposure:
The vehicle, corn oil and test substance formulations were administered orally by gavage via an appropriately sized flexible Teflon® shafted, stainless steel ball tipped dosing cannula once daily for 90-91 consecutive days, through the day prior to the scheduled necropsy. The dose volume for all groups was 5 mL/kg. Individual doses were based on the most recently recorded body weights to provide the correct mg/kg/day dosage.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Prior to the initiation of dose administration, samples for homogeneity determination were collected from the top, middle, and bottom strata of the 20 (100 mg/kg), 60 (300 mg/kg), and 200 (1000 mg/kg) mg/mL nondosing formulations which were sufficient to dose a group of animals for approximately 7 days. In addition, samples for resuspension homogeneity determinations were collected from the top and bottom strata of these same nondosing suspensions following room temperature (18°C to 24°C) storage for 10 days. Stability was evaluated comparing the inter-strata means to the overall concentrations from the bulk homogeneity data (time zero). Samples for concentration analysis were collected from the middle stratum of each dosing formulation (including the control group) prepared for dose administration during study weeks 0, 3, 7, and 12. One duplicate set was analyzed and the remaining duplicate set was stored at room temperature (18°C to 24°C) and retained as backup samples. All analyses were conducted by the WIL Research Analytical Chemistry Department using a validated gas chromatography method using flame ionization detection.
Duration of treatment / exposure:
90-91 days.
Frequency of treatment:
Daily
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 100, 300 and 1000 mg/kg/day.
Basis:
other: Verified oral gavage dose.
No. of animals per sex per dose:
Seventeen animals per sex per dose level. Ten animals per sex per dose were used for the standard O.E.C.D. test guideline 408 study protocol and seven rats per sex per dose were used for whole body perfusion and neurohistopathology assessment.
Control animals:
yes, concurrent vehicle
Details on study design:
Animals judged suitable for assignment to the study were selected for use in a computerized randomization procedure based on body weight stratification in a block design. Individual body weights at randomization were within ± 20% of the mean for each sex. The vehicle and test substance, Vinyl neononanoate formulations were administered orally by gavage on a daily basis for 90-91 days before scheduled sacrifice.

Clinical examinations were performed at the time of dose administration and 1-2 hours following dose administration. Individual body weights were recorded weekly (± 2 days) during the study period, and on the day prior to the first day of the scheduled necropsy (nonfasted). Individual food weights were recorded weekly (± 2 days) throughout the study. Food consumption was calculated as g/animal/day for the corresponding body weight intervals.

Functional, Observational Battery (FOB) assessments were recorded for all animals during study week 12. Testing was performed by the same technicians, whenever possible, without knowledge of the animals’ group assignments. The FOB was performed in a sound attenuated room equipped with a white noise generator set to operate at 70 ± 10 dB.

Blood and urine samples for clinical pathology evaluations (hematology, coagulation, serum chemistry, and urinalysis) were collected from all animals at the scheduled necropsy (study week 13). The animals were fasted overnight prior to blood collection while in metabolism cages for urine collection. Blood was collected for hematology and serum chemistry evaluation via the retro-orbital sinus of animals anesthetized by inhalation of isoflurane. Blood was collected for coagulation parameters at the time of euthanasia via the vena cava of animals euthanized by inhalation of carbon dioxide. Blood was collected into tubes containing potassium EDTA (hematology), sodium citrate (coagulation), or no anticoagulant (serum chemistry).

Ocular examinations were conducted on all animals during acclimation and near the end of the dosing period, study week 12. All ocular examinations were conducted using an indirect ophthalmoscope and slit lamp biomicroscope preceded by pupillary dilation with an appropriate mydriatic agent.

At scheduled sacrifice a complete necropsy was conducted on all animals. Animals were euthanized by carbon dioxide inhalation followed by exsanguination. O.E.C.D. test guideline and study protocol specified tissues and organs were collected and placed in 10% neutral buffered formalin. However, epididymides and testes were fixed in modified Davidson's solution and the eyes with optic nerve were fixed in Davidson's solution.

The following organs were weighed from all animals at the scheduled necropsy: Adrenals, Brain, Epididymides, Heart, Kidneys, Liver, Ovaries with oviducts, Pituitary, Prostate, Seminal vesicles, Spleen, Testes, Thymus, Thyroid with parathyroids, and Uterus. Paired organs were weighed together. Organ to final body weight and organ to brain weight ratios were calculated.

After fixation, protocol and O.E.C.D. test guideline specified tissues were trimmed and processed into paraffin block and and stained with hematoxylin and eosin. The testes were fixed in modified Davidson’s solution. Following routine histologic processing with paraffin embedding, testis sections were stained with hematoxylin and eosin as well as periodic acid/Schiff with hematoxylin counterstain. Hematoxylin and eosin stained paraffin sections were prepared for the kidneys from all animals found dead and from all animals in Groups 1-4 at the scheduled necropsy. Special stain (Chromotrope-Aniline Blue) for renal hyaline droplets was performed on the kidneys from all males in the control and 1000 mg/kg/day groups and 5 females randomly selected in the 1000 mg/kg/day group. Immunohistochemical stain for alpha-2u-globulin was performed on kidneys from all control and 100 mg/kg/day group animals.

For neuropathology assessment at the termination of the study 5 rats/sex/group were anesthetized by an intraperitoneal injection of sodium pentobarbital and then perfused in situ with a 4.0% paraformaldehyde/0.1M phosphate buffer solution. The central and peripheral nervous system tissues were dissected and preserved. The nervous tissues listed in the study protocol were prepared from all perfused animals in the control and 1000 mg/kg/day group rats for a qualitative histopathological examination by embedding in paraffin (central nervous system tissues) or plastic (peripheral nervous system tissues), sectioning, and staining with hematoxylin and eosin.



Positive control:
Not applicable.

Examinations

Observations and examinations performed and frequency:
All animalsplaced on study were observed twice daily, once in the morning and once in the afternoon, for mortality and moribundity. clinical examinations were performed at the time of dose administration and 1-2 hours following dose administration. The absence or presence of findings was recorded for individual animals at the scheduled intervals. Detailed physical examinations were conducted on all animals placed on study weekly (± 2 days) during the study period, and on the day of the scheduled necropsy.

Individual body weights were recorded weekly (± 2 days) during the study period, and on the day prior to the first day of the scheduled necropsy (nonfasted). Mean body weights and mean body weight changes were calculated for the corresponding intervals. Individual food weights were recorded weekly (± 2 days) throughout the study. Food consumption was calculated as gm/animal/day for the corresponding body weight intervals.

Functional Observational Battery (FOB) assessments were recorded for all animals placed on study during study week 12. The FOB used at WIL Research is based on previously published and developed protocols. Home gage, Handling, Open Field, Sensory and Neuromuscular including foot slpay and grip strength observations were made.

Locomotor activity, was assessed for all animals during study week 12. Locomotor activity was measured automatically using a personal computer controlled system that utilizes a series of infrared photobeams surrounding a clear, plastic rectangular cage to quantify an animal’s locomotor activity. The locomotor activity assessment was performed in a sound attenuated room equipped with a white noise generator set to operate at 70 ± 10 dB. Data were collected in 5 minute epochs (print intervals) and the test session duration was 60 minutes. These data were compiled as six 10 minute subsessions for tabulation.
Sacrifice and pathology:
Clinical pathology assessments included: hematology and coagulation, serum chemistry and urinalysis. Macroscopis examination included: external surface, all orifices, and the cranial, thoracic, abdominal, and pelvic cavities, and viscera. Study protocol and O.E.C.D. test guideline specified organs and tissues were taken and prepared for histological examination. The following organs were taken and weighed from all animals at the scheduled necropsy: Adrenals, Brain, Epididymides, Heart, Kidneys, Liver, Ovaries with oviducts, Pituitary, Prostate, Seminal vesicles, Spleen, Testes, Thymus, Thyroid with parathyroids, and Uterus. Following in situ perfusion, study protocol specificed nervous tissues were taken and prepared for neurohistopathological examination.
Statistics:
Analyses were conducted using two-tailed tests (except as noted otherwise) for minimum significance levels of 1% and 5%, comparing each test substance-treated group to the control group by sex. Body weight, body weight change, food consumption, continuous FOB, clinical pathology, and organ weight data for Toxicology Groups 1-4 were subjected to a parametric one way ANOVA to determine intergroup differences. If the ANOVA revealed statistically significant (p<0.05) intergroup variance, Dunnett's test was used to compare the test substance treated groups to the control group. For Toxicology Groups 1-4, functional observational battery parameters that yielded scalar or descriptive data were analyzed using Fisher’s Exact Test. A repeated measures analysis of variance (RANOVA) statistical analyses for total and ambulatory locomotor activity counts recorded prior to the initiation of dose administration and after dosing was conducted by SAS procedure PROC MIXED for analysis with the random effect of animal included as the repeated measurement.

Results and discussion

Results of examinations

Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
There was no test substance-related lethality observed at any dosage level. Test substance-related clinical observations noted for the 300 and 1000 mg/kg/day group animals included the following: yellow and/or red material on various body surfaces and/or red and/or clear discharge from the eye(s). The yellow material was generally observed in the anogenital/urogenital area of the animal at low incidence in the high dose group.
Mortality:
mortality observed, treatment-related
Description (incidence):
There was no test substance-related lethality observed at any dosage level. Test substance-related clinical observations noted for the 300 and 1000 mg/kg/day group animals included the following: yellow and/or red material on various body surfaces and/or red and/or clear discharge from the eye(s). The yellow material was generally observed in the anogenital/urogenital area of the animal at low incidence in the high dose group.
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
Slightly lower mean absolute and cumulative body weight gains were noted generally throughout the study for the 1000 mg/kg/day group males and resulted in a statistically significantly (P < 0.05) lowerrelative cumulative mean body weight gain of 12%.
Food consumption and compound intake (if feeding study):
no effects observed
Food efficiency:
no effects observed
Water consumption and compound intake (if drinking water study):
not specified
Ophthalmological findings:
no effects observed
Haematological findings:
effects observed, treatment-related
Description (incidence and severity):
In the male animals at the high dose of 1000 mg/kg/day significantly reduced (P < 0.01) reduced mean erythrocyte count, hemoglobin and hematocrit were observed. Also, in the high dose males the mean platelet count was significantly (P < 0.01) increased.
Clinical biochemistry findings:
effects observed, treatment-related
Description (incidence and severity):
At 1000 m/.kg/day higher total protein, albumin, globulin, urea nitrogen, creatinine, cholestrol and calcium were observed. Urea nitrogn and creatinine were elevated in males only.
Urinalysis findings:
effects observed, treatment-related
Description (incidence and severity):
Total urine volume was statistically higher (P < 0.01) in the 1000 mg/kg/day group males and females and the urine specific gravity values were lower, but not statistically significant.
Behaviour (functional findings):
no effects observed
Description (incidence and severity):
No notable test substance related effects were observed.
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
Group mean higher adrenal gland, liver and kidney weights in males and females at 1000 mg/kg/day. Lower group mean prostate and seminal vesiciles in males at 1000 mg/kg/day.
Gross pathological findings:
effects observed, treatment-related
Description (incidence and severity):
Test substance-related macroscopic changes were limited to pale kidney (8/10) and small prostate and seminal vesicle (3/10) in the 1000 mg/kg/day group males.
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
Kidney hyaline droplet accumulation in males at all dose levels and heptocyte hypertrophy at 300 and 1000 mg/kg/day in males and females.
Histopathological findings: neoplastic:
no effects observed
Description (incidence and severity):
Kidney hyaline droplet accumulation in males at all dose levels and heptocyte hypertrophy at 300 and 1000 mg/kg/day in males and females.
Details on results:
The analyzed dosing formulations were found to contain 103% to 113% of the test substane, Vinyl neononanoate which was within the WIL Research SOP range of target concentrations for suspensions (85% to 115%), were homogeneous, and were stable for 10 days of room temperature storage.
There was no test substance-related mortalities observed at any dosage level during the study. Test substance-related clinical observations noted for the 300 and 1000 mg/kg/day group animals included the following: yellow and/or red material on various body surfaces and/or red and/or clear discharge from the eye(s). The yellow material was generally observed in the anogenital/urogenital area of the animal at low incidence in the high dose group. Detailed Clinical Observation may be seen in the attached Summary Data Tables.

Slightly lower mean absolute and cumulative body weight gains were noted generally throughout the study (study weeks 0-13) for the 1000 mg/kg/day group males and resulted in a statistically significantly (P < 0.05) lower cumulative mean body weight gain of 12%) from study weeks 0-13 when compared to the control group. During study week 13, the mean body weight for the 1000 mg/kg/day group males was 5.9% lower (not statistically significant) than the concurrent control group. For the female animals a statistically significantly (P < 0.05) higher cumulative mean body weight gain of 21.% was noted for the 1000 mg/kg/day group females when compared to the control group during study weeks 0-13. During study week 13, the mean body weight for the 1000 mg/kg/day group females was 5.8% higher (statistically significant) than the concurrent control group. Details of body weight gain may be seen in the attached Figures and Summary Data Tables. There were no significant test substance-related effects on food consumption. Mean food consumption for the 1000 mg/kg/day group males and females was slightly higher (1 2 g/animal/day) than the control group throughout the study.

During the Functional Observational (FOB) assessment there were no test substance related, Home Gage, Handling, Open Field, Sensory and Neuromuscular including grip strength measurment observations. Within-session repeated measures analyses of variance for locomotor activity were conducted across the subintervals of each test session for total and ambulatory counts and for the overall interval means (representing the entire 60-minute session activity) during each test session. Locomotor activity patterns (mean ambulatory and total motor activity counts) were unaffected by test substance administration for males and females at any dose level.

Hematological evaluation demonstrated In the male animals at the high dose of 1000 umg/kg/day, significantly reduced (P < 0.01) mean erythrocyte count, hemoglobin and hematocrit. Theses values were reduced 10 – 12.5% relative to the mean control values. Also, in the high dose males the mean platelet count was significantly (P < 0.01) increased 1.4-fold relative to the control value.

Male Rat Hematological Values
Analysis Group 0 mg/kg 100 mg/kg 300 mg/kg 1000 mg/kg
RBCs (mil/uL) 9.73 9.55 9.13* 8.58*
HGB (gm/dL) 16.0 15.8 15.3 14.0*
HTC % 47.6 47.3 45.5 42.7*
Platelets (tho/uL) 625 596 682 889*
__________________________________________________________________
* P < 0.01

Although stastically significant, these hematological values are within published historical untreated control values for the Fischer 344 male rat (B. S. Levine, Animal Clinical Pathology. In: M. J Derelanko and M. A. Hollinger (Eds.) CRC Handbook of Toxicology. CRC Press. 517-538, 1995.).

Female animals had lower mean corpuscular hemoglobin hemoglobin concentration in the 1000 mg/kg/day group. Platelet count was statistically significantly (P < 0.01) higher in the 1000 mg/kg/day group males and slightly higher but not statistically significant in the 1000 mg/kg/day group females. The higher platelet count in the 1000 mg/kg/day group males and females was considered test substance-related. No significant changes in the total white blood cell (WBC) count were noted in the group mean values of any test substance-treated male and female animals. Details of the hematological assessment may be seen in the attached Summary Data Tables.

Test substance-related effects on serum chemistry consisted of the following: higher total protein, albumin, and globulin values in the 1000 mg/kg/day group males and females; higher urea nitrogen and creatinine at all dose levels in males; higher cholesterol in the 1000 mg/kg/day group males and 300 and 1000 mg/kg/day group females; higher calcium values in the 300 and 1000 mg/kg/day group males and in all test substance-treated group females, lower glucose in the 300 and 1000 mg/kg/day group males and females; and lower chloride in the 1000 mg/kg/day group males and females.

Test substance-related, higher total protein with higher albumin and globulin values were noted in the 1000 mg/kg/day group males and females. In the high dose male animals these parameters were significantly (P < 0.01) elevated with albumin increased 14%, globulin increased 19% and total protein increased 16% relative to the corresponding control value. Statistically significant higher total protein, albumin and globulin values were also noted in the 100 and 300 mg/kg/day group females; however, these changes were considered biological variation and not related to the test substance administration because individual values were similar to the range of control animals.

Dose dependent, test substance-related higher urea nitrogen values and higher creatinine values were noted in the 100, 300, and 1000 mg/kg/day group males. These values were significantly (P < 0.01) increased at the high dose level. High dose mean urea nitrogen was elevated 49% and mean creatinine was elevated 67% relative to the corresponding control values. Similar changes were not seen in any test substance-treated group females. Test substance-related higher calcium values were noted in the 300 and 1000 mg/kg/day group males and in all test substance-treated group females in a dose-dependent manner. This elevation of calcium was significant (P < 0.01) at the high dose. Test substance-related higher cholesterol values were noted in the 1000 mg/kg/day group males and in the 300 and 1000 mg/kg/day group females. These increases were significant (P < 0.01) at the high dose. At the high dose the cholesterol level was increased 24% in the females relative to the control value and in the males the cholesterol level was increased 43%.

Test substance-related lower glucose values were noted in the 300 and 1000 mg/kg/day group males and females and was significant (P < 0.01) at the high dose. At 1000 mg/kg/day the glucose level was reduced 19-24% relative to the control values. Test substance-related lower chloride values were noted in the 1000 mg/kg/day group males and females. Details of the Serum Chemistry assessment may be seen in the attached Summary Data Tables.

Urinalysis assessment demonstrated that total urine volume was statistically higher (P < 0.01) in the 1000 mg/kg/day group males and females and the urine specific gravity values were lower, but not statistically significant, in the 1000 mg/kg/day group males and females. The increased urine volume was 2.8-fold higher in males and 5.8-fold higher in females relative to the corresponding control values. Considering the other clinical pathology and histopathology findings, the higher urine volume and lower urine specific gravity values in the 1000 mg/kg/day group males were considered test substance-related. The pH values were statistically significantly lower in the 1000 mg/kg/day group males and females; however this change was not considered biologically important because individual values were not affected.

Urinalysis Urin Total Volume
_________________________________________________________________________________
Males 0 mg/kg 100 mg/kg 300 mg/kg 1000 mg/kg
(mL) 3.6 5.7 4.8 10.0*
Females
(mL) 2.6 3.8 4.5 15.1*
______________________________________________________________________________
* P < 0.01 (males) P < 0.05 (females)

No ophthalmic lesions indicative of toxicity were observed in any of the test substance treated groups. All findings observed were typical in prevalence and appearance forFischer 344 laboratory rats of this age.

Macroscopic pathology examination demonstrated that test substance-related macroscopic changes were limited to pale kidney (8/10) and small prostate and seminal vesicle (3/10) in the 1000 mg/kg/day group males. Test substance-related kidney findings in the 1000 mg/kg/day group males were described as pale which corresponded microscopically toHyalin droplet/alpha 2µ globulin nephropathy. Pale kidneys were also described for one 100 mg/kg/day group male and two 300 mg/kg/day group males for which the microscopic corresponding finding was hyaline droplet accumulation in proximal tubular epithelium and lumina, presumed to be alpha 2µ globulin nephropathy.

Test substance-related macroscopic observations pertaining to small prostate and seminal vesicle were noted for 3/10 of the 1000 mg/kg/day group males, microscopically, these prostates and seminal vesicle were comparable to those of the control groups and considered within normal limits; therefore, no corresponding microscopic findings were observed for these statistically significant decreases in the 1000 mg/kg/day group male prostates and seminal vesicles.

Group mean organ analysis foundsStatistically significant increased absolute and relative adrenal weight increases for the 300 and 1000 mg/kg/day group males and females, (P < 0.01). At the high dose level the male relative increase was 29% and female relative increase was 20%. A similar significant (P < 0.01 at 1000 mg/kg/day) pattern was observed for increased kidney weights for the 300 and 1000 mg/kg/day group males and females. At the high dose the male relative kidney weight was increased 42% and the female relative kidney weight was increased 17% relative to the untreated control value. Statistically significant (P < 0.01 at 1000 mg/kg/day) increased absolute and relative (to body weight and to brain weight) liver weights were also observed in the 300 and 1000 mg/kg/day group males and females. At the high dose of 1000 mg/kg/day the male relative liver weight was increased 72.3% and the female relative liver weight was increased 72%. For the increased liver weights in the 300 and 1000 mg/kg/day group males and females, the microscopic correlate was centrilobular hepatocyte hypertrophy. No microscopic correlate was apparent for the 1000 mg/kg/day group increased adrenal weights.

Statistically significant decreased (P < 0.05) group mean absolute and relative prostate and seminal vesicle weights were observed for 1000 mg/kg/day males. The high dose mean prostate and seminal vesicles weights were reduced 21-24% relative to the control weight values. Microscopically, these prostates and seminal vesicles were comparable to those of the control groups and considered within normal limits with no histopathological features. Statistically significant increased relative (to body weight) spleen weight was observed in all male dose groups. For 1000 mg/kg/daymale dose group, there was no microscopic corresponding finding for the observed spleen weight increase. Details of group mean organ assessments may be seen in the attached Summary Data Tables.

Microscopic histopthological assessment demonstrated test substance treatment-related findings in the kidney of all treated male groups and the liver of the 300 and 1000 mg/kg/day group males and females In the kidney, Chromotrope-Aniline Blue (CAB) stain was performed to demonstrate hyaline droplets and the alpha 2µ globulin immunohistochemical-stain confirmed that these hyaline droplets were alpha 2µ globulin protein. Associated with the alpha 2µ globulin nephropathy in the 1000 mg/kg/day group males were a number of histopathological changes typically described as part of the nephropathy and included the presence of granular casts, necrosis of individual tubular epithelial cells, and sloughed cells in the tubular lumina. The CAB stain was routinely negative for female rats, indicating the absence of visible hyaline droplets by light microscopy.

In the liver, centrilobular hypertrophy had a dose-related increase in incidence in the males. Centrilobular hypertrophy at a slightly lesser incidence occurred in 300 and 1000 mg/kg/day group females compared to the control groups.

Neuralhistopathological examination of the cervical spinal cord from the 1000 mg/kg/day group females demonstrated a slightly greater incidence of generally minimal axonal degeneration in the spinal cord at all levels compared to control females in the toxicology portion of this study. However, the study pathologist considerd this finding not test substance related. The incidence of axonal degenerative changes in control and 1000 mg/kg/day group male spinal cord levels was low and roughly comparable.





Effect levels

Dose descriptor:
NOAEL
Effect level:
ca. 300 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male
Basis for effect level:
other: see 'Remark'

Target system / organ toxicity

Critical effects observed:
not specified

Applicant's summary and conclusion

Conclusions:
The outcome of the Functional Observational Battery (FOB) Motor Activity analysis and neurohistopathological assessment demostrated that the test substance, Vinyl neononanoate is not neurotoxic to Fischer 344 rats under the conditions of this study.

The higher platelet count noted in the 1000 mg/kg/day group males and females could be secondary to decreased red cell parameters (reactive thrombocytosis). Mildly lower group mean hematocrit, erythrocyte count,and hemoglobin noted in the 300 and 1000 mg/kg/day group males were considered test substance-related and suggestive of a regenerative anemia.

The higher total protein with higher albumin and globulin values noted in the 1000 mg/kg/day group males and females were most likely attributed to dehydration. The degree of dehydration was not severe enough to be clinically recognized; therefore this change was considered non-adverse. The significantly higher urea and creatinine values noted at all dose levels in the males rats were related to the renal lesions observed histopathologically. The higher calcium values noted in the 300 and 1000 mg/kg/day group males and in all test substance treated group females were most likely related to hemoconcentration and increased calcium carrying plasma proteins (albumin). Test substance-related higher cholesterol in the 1000 mg/kg/day group males and the 300 and 1000 mg/kg/day group females was likely related to altered lipid metabolism.

Alpha 2µ globulin nephropathy was observed in the male rats in this study. Alpha 2µ globulin nephropathy is recognized as a sex and species specific disease in rats that has no correlation to human exposure since humans do not manufacture or excrete alpha 2µ globulin protein (Swenberg, 1993; C. D. klaassen, Ed. Casarett and Doull's Toxicology. 6th Edition, 2001). Therefore, this male rat finding is not appropriate to use for human health risk assessment.

A dose-dependent with respect to incidence increase in centrilobular hepatocyte hypertrophy (liver cell enlargement) was seen at all dose levels in thetest substance treated males and 300 and 1000 mg/kg/day group females, which contributed to the increased liver weights observed in 300 and 1000 mg/kg/day group animals. This change in the liver of was considered non-adverse. Centrilobular hepatocyte hypertrophy is recognized to be an adaptive change in the absence of other indicators of hepatic toxicity, as occurred in this study (Cattley et al., 1999 and Hall et al., 2012).

Based on this findings a No-Observed-Adverse-Effect-Level (NOAEL) of 300 mg/kg/day is established for the Fischer 344 rat under the conditions of this O.E.C.D. 408 90-day subchronic study.
Executive summary:

An O.E.C.D. test guideline 408 90-day subchronic oral gavage study was conducted in male and female Fischer 344 rats on the test substance Vinyl neononanoate at analytically verified dose levels of 0, 100, 300 and 1000 mg/kg/day. Based upon significantly different findings of hematological, serum chemistry, organ weights, macroscopic and histopatholpgical parameters a No-Observed-Adverse-Effect-Level (NOAEL) of 300 mg/kg/day was established.