2-vinylpyridine

Repeated dose toxicity: oral

Administrative data

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

7 Nov 1983-21 Aug 1984

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Preceeds but is comparable to OECD Guideline 408, adopted in 1998.

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1984

Report date:

1984

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)

Deviations:

yes

Remarks:

Test material administered 5 days per week; this study precedes the recommendation of 7 days per week adminstration.

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

2-vinylpyridine

EC Number:

202-879-8

EC Name:

2-vinylpyridine

Cas Number:

100-69-6

Molecular formula:

C7H7N

IUPAC Name:

2-ethenylpyridine

Details on test material:

2-Vinylpyridine was obtained from Reilly Tar and Chemical Corporation, Lot # 30912, and was purified by distillation. Average purity was 97.34 ± 0.15%. There was 1 major impurity (1.9%) and three minor impurities in the material used in the study. The concentration of 2-vinylpyridine was determined by UV/Vis spectroscopy. Concentrations of test material were prepared in corn oil and kept refrigerated in amber glass bottles.

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

Weanling rats (3 weeks old, CRL: COBS-CD-(SD)BR) were obtained from Charles River Breeding Laboratory, Wilmington, MA. The animals were quarantined for 12 days prior to the start of the study. Serology was performed on selected animals, and positive titers were observed for Toolan H-1 and RCV/SDA viruses. The animals were about 6 weeks at the start of the study. Thirty males and 30 females were assigned to each experimental group. Rats were housed in a room with a laminar air flow system with HEPA filtration and 6% fresh air replacement during each air cycle (157/hour). The room was maintained at 70-76 degrees F and 35% relative humidity with a 12-hour light period. Animals were kept one per stainless steel wire-mesh cage fitted with an automatic watering nipples. Cages of animals of different dose levels were distributed randomly on racks. Racks were washed weekly. Feed was Purina Certified TM Rodent Chow #5002 and was available ad libitum. Water was supplied ad libitum through an automatic watering system. The source of the water was Monroe County Water Authority (New York). No interfering substances were known to be present in the feed or water.

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on oral exposure:

Dose levels selected were 0, 20, 60 and 180 mg/kg body weight/day of 2-VP given by gavage once daily excluding weekends. These doses were selected based results in preliminary studies.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The concentration of the test material in corn oil was assayed (UV/Vis spectroscopy) throughout the experimental period. 2-Vinylpyridine was determined to be stable for at least 11 days, as prepared and stored.

Duration of treatment / exposure:

92 days, 5 days per week excluding weekends.

Frequency of treatment:

Once daily, excluding weekends.

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 20, 60, 180 mg/kg body weight/day
Basis:
actual ingested

No. of animals per sex per dose:

30

Control animals:

yes, concurrent vehicle

Details on study design:

Body weights were determined prior to the start of the study and on days 0, 4, 7 and weekly thereafter.
Feed consumption was determined on days 4, 7 and weekly thereafter.

Positive control:

none

Examinations

Observations and examinations performed and frequency:

Every work day in the morning each rat was removed from its cage for examination and gavage by a trained technician. Every work day, post dose, and in the afternoon, cageside observations were conducted, including examination of hair, skin, eyes, motor activity, faeces and urine. Prior to, and during the last week of the study, all rats were examined by a veterinarian using indirect opthalmoscopy.

Sacrifice and pathology:

An interim necropsy was performed at 43 days. Ten randomly selected rats of each sex per dose level were killed, bled and necropsied. The remaining 20 rats of each group were necropsied during the week following the 90-day exposure period. Rats found dead during the study were promptly necropsied. Rats were fasted overnight, anesthetized with CO2 and exsanguinated by severing the posterior vena cava after collecting blood samples. The following organs were weighed and their weights relative to body weight and to brain weight calculated: liver, kidney, spleen, brain, heart, adrenal glands, ovaries, testes. The following organs were examined and collected in 10% buffered formalin: trachea, lungs, aorta, tongue, esophagus, stomach, duodenum, jejunum, ileum, colon, cecum, rectum, urinary bladder, pituitary gland, pancreas, thyroid glands, parathyroid glands, thymus, mesenteric lymph nodes, bone marrow, cervical spinal cord, sciatic nerve, eyes, skin, femur, rib, salivary glands, vagina, fallopian tubes, female mammary gland, uterus, epididymides, accessory sex organs (male), male mammary gland. Eyes were fixed in modified Zenker's (Russell's) fixative. All tissues from high and control groups were examined histopatholgically. Target organs and gross lesions from other dose levels and interim sacrifice groups were also examined histologically.

Other examinations:

At necropsy, blood was collected from the posterial vena cava while the rats were under CO2 anesthesia. All rats from each group were bled for hematologic and clinical chemistry evaluations, performed by the Eastman Kodak Animal Clinical Chemistry Group. Serum clinical chemistry tests included: AST, ALT, AP, urea nitrogen, glucose, creatinine, LDH, GGTP, potassium, calcium, cholesterol, sodium, chloride, phosphorus. Hematology tests included: hemoglobin concentration, hematocrit, red blood cell count, white blood cell count, differential while blood cell count, platelet count, red blood cell indices, cell morphology.

Statistics:

All numerical data were evaluated using computerized tests as follows: One-way analysis of variance, Bartlett's test and Duncan's multiple range test. F-tests were performed where the Bartlett's test indicated a significant difference in variances which would interfere with interpretation of analytical results.

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

slight but statistically nonsignificant reduction in body weight at the high dose of 180 mg/kg bw/d.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

Statistically significant decrease in food consumption by high dose male rats.

Food efficiency:

not specified

Water consumption and compound intake (if drinking water study):

not specified

Ophthalmological findings:

no effects observed

Description (incidence and severity):

No ophthalamoligic effects related to 2VP were observed.

Haematological findings:

no effects observed

Description (incidence and severity):

Increased platelet counts observed in the high dose group were not determined to be of biological relevance.

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

Decreased aminotransferase in males. In a separate study, this was statistically signifiant.

Urinalysis findings:

effects observed, treatment-related

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

Organ weights were confounded by decreased body weights at the high dose.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

There was no pathology except in the glandular stomach.

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Degeneration of the epithelial cells, hyperkeratosis and acanthosis.

Histopathological findings: neoplastic:

not examined

Details on results:

Four rats died during the experiment, 2 from inadvertant administration of test solutions into the lungs.
No systemic clinical signs were observed. Three rats demonstrated convulsions after dosing at the high dose level on/after day 87; three other rats demonstrated hematuria.
Body weight measurements: statistically significant reduction in weight gain (15%) in males at the high dose of 180 mg/kg/day, in conjunction with statistically significant decrease in food consumption; the body weight gain decrement in female rats at the high dose was 7%.
Increased platelet counts in males (60 and 180 mg/kg/day) and in females (180 mg/kg/day), which are probably neither treatment-related nor biologically significant. These effects occur often in controls, and in this experiement, control levels were extraordinarily low.
A decrease in mean AST values was dose dependent and statistically significant in the mid and high dose males, in conjunction with an increase in relative liver weight.
Organ weight analysis was confounded in both males and females by reduction of body weight gain in animals receiving 180 mg/kg/day. Doses of 20 and 60 mg/kg/day had no effect on terminal body weight. For males, absolute weight increases were seen in brain, heart and adrenal gland; relative weight increases were seen in liver, kidney, brain, adrenal glands, testes and heart. In females at the high dose only, absolute weight increases were seen in the liver, kidneys and ovaries, and relative weight changes in the liver and ovaries.
In the reproductive organs of both male and female, increases in relative weights of the testes and ovaries occurred only in the high dose groups of 180 mg/kg/day.
The high dose was irritating to the non-glandular stomach epithelium of both sexes by the presence of acanthosis, hyperkeratosis, edema, chronic inflammation and congestion. Microscopically, this was characterized by degeneration of epithelial cells, hyperkeratosis and acanthosis resulting in thickening of the non-glandular epithelium.
In rats euthanized in the interim sacrifice, stomach irritation was seen in the mid and high dose groups.

Effect levels

1

Dose descriptor:

NOAEL

Effect level:

20 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male

Basis for effect level:

other: see 'Remark'

2

Dose descriptor:

LOAEL

Effect level:

20 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Irritation and inflammatory responses in the stomach are the result of gavage dosing of a corrosive substance, and are considered local effects with a LOAEL of 20 mg/kg bw/day.

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

It is not unexpected to observe gastric epithelial damage consistent with irritation and inflammation after gavage for a 90-day period with a highly irritating or corrosive material. This can be considered a "local" effect and not a systemic effect of overall toxicity. Decreased food consumption affecting body and organ weights would also be a consequence of gastric irritation and inflammation. This may result in decreased body weight gain and organ weights. In males, testes weight relative to body weight was increased in the high dose group, but this could be due to the decreased body weight and decreased food consumption. While changes in relative testes weight were also seen in males in the interim sacrifice, these were not dose-related nor seen in rats sacrificed after 92 days. In females, ovary weight relative to body/brain weight was also increased in the high dose group concurrent with a decrease in body weight.

Applicant's summary and conclusion

Conclusions:

The primary effect of a 90-day oral exposure to 2-vinylpyridine was reduced body weight in animals dosed at the high dose of 180 mg/kg/day, with male rats demonstrating a greater effect than female rats, resulting in relative weight changes. With the exception of the non-glandular stomach, 2-vinylpyridine was remarkably non-toxic by the oral route. Daily oral administration by gavage resulted in irritation, chronic inflammation and congestion in the non-glandular stomach, with some histopathological effects seen in all dose groups. Concurrent with this finding, and likely due to these effects, food consumption in males was significantly decreased. Body weight was significantly decreased in both sexes at the high dose level of 180 mg/kg/day. The mid (60 mg/kg/day) dose produced minor hematologic and clinical chemistry changes in male rats, increased relative liver to body weight ratios of both sexes, increased relative liver to brain weight ratios in female rats, and gross and histopthologic changes ascribed in both sexes to irritation of the stomach. The No Observed Adverse Effect Level (NOAEL) was 20 mg/kg body weight/day for systemic effects, and the LOAEL was 20 mg/kg bw/d for local corrosive effects in the stomach (portal of entry).