Vinyl acetate

Repeated dose toxicity: oral

Administrative data

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP compliant, guideline study, available as unpublished report, no restrictions, fully adequate for assessment.

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1980

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:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Vinyl acetate

EC Number:

203-545-4

EC Name:

Vinyl acetate

Cas Number:

108-05-4

Molecular formula:

C4H6O2

IUPAC Name:

ethenyl acetate

Details on test material:

- Name of test material (as cited in study report): Vinyl acetate
- Supplied by: BP Chemicals Ltd., West Glamorgan, UK
- Physical state: Colourless liquid
- Analytical purity: 99.9%
- Lot/batch No.: T205R/X
- Storage: In a cool area in stainless steel drums which were electrically earthed.
- Other: Hydroquinone was deliberately omitted from the vinyl acetate batch supplied.

Test animals

Species:

rat

Strain:

other: CD

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River UK Ltd, Margate, Kent, UK
- Age at study initiation: 5 weeks
- Weight on arrival (21 days old): 45 g
- Housing: Individually in stainless steel mesh cages suspended over cardboard-lined trays
- Diet.: Rodent Breeding diet (Spratts Patent Ltd, Barking, Essex, UK.) ad libitum except for approximately 16 hrs during urine collection and prior to blood sampling and necropsy.
- Water: drinking water solutions were available ad libitum except for approximately 16 hrs during urine collection. Untreated tap water was provided on the night prior to necropsy. Drinking water solutions were dispensed from glass bottles fitted with stainless steel spouts, water solutions and untreated drinking water was replaced with fresh solution every 24 hours.
- Acclimation period: 2 weeks

ENVIRONMENTAL CONDITIONS
- Temperature: 18-25°C
- Humidity: 40-60%
- Air changes (per hr): 18-20
- Photoperiod: 12 hrs dark / 12 hrs light (0600-1800)

IN-LIFE DATES: From: May 1979 To: August 1979

Administration / exposure

Route of administration:

oral: drinking water

Vehicle:

water

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:
- Batches of each drinking water concentration were prepared daily. The measured volume of vinyl acetate, taken from the newest drum available, was added to approximately 2 litres of tap water and dissolved. Dissolution was facilitated by shaking (for final concentrations of up to 1000 ppm) or by magnetic stirring (for concentrations greater than 1000 ppm). The solutions were then made up to the final volume with tap water and re-shaken.
- Drinking water for group 5 (control) animals was drawn from the same source.
- The pH of the tap water was recorded at approximately one week intervals for the first 6 weeks of the study, and daily from week 7 to the end of the study.
- Drinking water solutions were stored in tightly capped brown glass bottles bearing group-related coloured labels showing the project number, test article identity and concentration, group number and the date of preparation.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Samples (200 mL) of each drinking water formulation were taken into stoppered, glass bottles immediately after preparation and the concentration of vinyl acetate determined by chromatography. Analysis was carried out daily for the first 4 days of the treatment period and monthly thereafter. During the latter part of the treatment period the formulations were also analysed for acetaldehyde.

The stability of vinyl acetate in water was investigated before the beginning of this study (HLE project number 51/1, report number 1932-51/1).

Duration of treatment / exposure:

3 months and until necropsy

Frequency of treatment:

Daily, 7 days each week

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
0, 200, 1000 or 5000 ppm (v/v)
Basis:
nominal in water

Doses / concentrations 2

Remarks:

Doses / Concentrations:
0, 31, 163 or 684 mg/kg/day (males)
Basis:
other: calculated mean achieved dose

Doses / concentrations 3

Remarks:

Doses / Concentrations:
0, 36, 193 or 810 mg/kg/day (females)
Basis:
other: calculated mean achieved dose

No. of animals per sex per dose:

40

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: Dose levels of 200, 1000 and 5000 ppm were selected on the basis of a 4 week dose range-finding study where, at 10000 ppm vinyl acetate in water, there were no major signs of toxicity but water consumption was reduced.
- Rationale for animal assignment (if not random): Animals were allocated to groups using a stratified randomisation procedure based on bodyweight classes. Animals not assigned to the study were killed by exposure to carbon dioxide.

Examinations

Observations and examinations performed and frequency:

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Twice daily for signs of ill health or overt toxicity.

BODY WEIGHT: Yes
- Time schedule for examinations: Prior to the start of treatment and then at weekly intervals and at necropsy.

FOOD CONSUMPTION :
- Individual food consumption was determined weekly for 13 weeks.

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): Yes
- Time schedule for examinations: The amount of water (by weight) consumed by each animal was recorded daily for 13 weeks.

OPHTHALMOSCOPIC EXAMINATION: Yes
- Both eyes of all rats were examined after 12 weeks of treatment using a Keeler direct ophthalmoscope following pupil dilatation with 1% tropicamide solution (Mydriacil, Alcon Laboratories, Texas, USA).

HAEMATOLOGY: Yes
- Time schedule for collection of blood: After 4 and 12 weeks of treatment.
- Anaesthetic used for blood collection: Yes, diethyl ether (Analar Grade, BDH chemicals, Poole, Dorset, UK)
- Animals fasted: Yes (overnight, approximately 16 hours)
- How many animals: 10 males and 10 females in control and 5000 ppm groups only.
- Parameters checked examined: Haemoglobin concentration (Hb), mean cell volume (MCV), red blood cell count (RBC), white blood cell count (total and differential) (WBC), reticulocyte count (Retics).
The following indices were calculated:-packed cell volume (PCV), mean cell haemoglobin (MCH), mean cell haemoglobin concentration (MCHC).
- At necropsy, a femoral bone marrow smear from each animal was stained with May-Grunwald-Giemsa stain. Subsequently, 1000 erythrocytes in the smear were scored for the presence of micronuclei.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: after 4 and 12 weeks of treatment
- Anaesthetic used for blood collection: Yes, diethyl ether (Analar Grade, BDH chemicals, Poole, Dorset, UK)
- Animals fasted: Yes (overnight, approximately 16 hours)
- How many animals: 10 males and 10 females in control and 5000 ppm groups only.
- Parameters checked: Creatine phosphokinase activity (CPK), glutamic-oxaloacetic transaminase activity (GOT), glutamic-pyruvic transaminase activity(GPT), alkaline phosphatase activity (Alk.P),sodium ions, potassium ions, glucose, blood urea nitrogen (BUN), total protein, albumin, albumin/globulin ratio (A/G ratio).

URINALYSIS: Yes
- The following parameters were investigated: Quantitatively: volume and specific gravity. Semi-quantitatively: colour, pH, protein, glucose, ketones, bilirubin, blood, urobilinogen.
- The urine samples were centrifuged at 1000 rpm for 5 minutes and the precipitate examined for epithelial cells, leucocytes, erythrocytes, casts, crystals and abnormal constituents.

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
- With the exception of eyes which were fixed in Davidson's fluid and the bone marrow smear which was fixed in methanol, samples of the following tissues and organs were fixed in 10% buffered formalin. Adipose tissue, adrenals, aorta (abdominal), bladder, bone marrow smear (femoral), brain (cerebellum, cerebrum, stem), ear canal, eyes, fallopian tubes, spinal ganglia (lumbar, sacral and dorsal), gross lesions, heart, hind limbs (post-distal portions, for examination of tibial and plantar nerves), kidneys, large intestine (caecum, colon, rectum), larynx, liver, lungs, lymph nodes (mediastinal, mandibular, mesenteric and bronchial), mammary gland, nasal turbinate, oesophagus, pancreas, parathyroid (where present with thyroid), peripheral nerve, (sciatic), pituitary, prostate/uterus, salivary gland (submaxillary), skeletal muscle (quadriceps), skin (flank), small intestine (duodenum, ileum, jejunum), spinal cord (high cervical), spleen, stomach, testes/ovaries, thymus, thyroid, tongue, trachea.

ORGAN WEIGHTS: Yes
- The following organs were weighed prior to fixation: adrenals, brain, heart, kidneys, liver, lungs, pituitary, spleen, testes, thymus.

HISTOPATHOLOGY: Yes
- With the exception of the bone marrow smears, ear canal, lumbar, sacral and dorsal ganglia, and tibial and plantar nerves, the tissues listed from all control and high dose animals were processed as paraffin blocks, sectioned at a nominal thickness of 5 µm and stained with luxol fast blue (brain, spinal cord and sciatic nerve only).

Statistics:

Weekly body weight gains, food consumption, haematology data (except derived indices and proportional WBC counts), absolute organ weights and relative organ weights were examined by analysis of variance followed by a 't' test.
Blood chemistry data (except derived indices) were analysed by the Kruskal-Wallis test and Wilcoxons rank-sum test.

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Food efficiency:

not examined

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

effects observed, treatment-related

Ophthalmological findings:

no effects observed

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

effects observed, treatment-related

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Details on results:

BODY WEIGHT AND WEIGHT GAIN
- A slight degree of growth retardation was apparent in male animals treated at 5000 ppm, which resulted in a group mean body weight which was 8% lower than the controls after 13 weeks of treatment. However, the overall body weight gain was not statistically significantly different (p>0.05) from that of the controls.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study)
- The overall food consumption of high dose male and female animals was 7 and 4% (respectively) lower than the controls.

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study)
- The water consumption of high dose male and female animals and of intermediate dose male animals was consistently lower than that of the controls throughout the course of the study. The effect at the intermediate dose level was less marked than at the high dose level. The water consumption of low dose male animals was marginally lower than the controls during the first 2 weeks of exposure. Subsequently, the water consumption of these animals was similar to the controls, as was that of the female animals in the low and intermediate dose groups

URINALYSIS
- After 12 weeks of treatment, high dose females generally showed a more concentrated and slightly darker coloured urine when compared with the controls.

Effect levels

1

Dose descriptor:

NOAEL

Effect level:

5 000 ppm

Sex:

male/female

Basis for effect level:

other: no toxicologically significant clinical or histopathological effects

2

Dose descriptor:

NOAEL

Effect level:

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

Sex:

male

Basis for effect level:

other: mg/kg in drinking water

3

Dose descriptor:

NOAEL

Effect level:

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

Sex:

female

Basis for effect level:

other: mg/kg in drinking water

Target system / organ toxicity

Critical effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

The NOAEL of vinyl acetate in drinking water was 5000 ppm, equivalent to an average daily dose level of 684 mg/kg in the male rat and 810 mg/kg in the female rat.

Executive summary:

Groups of Sprague-Dawley CD rats (10 males and 10 females) were given vinyl acetate in the drinking water at nominal concentrations of 0, 200, 1000 or 5000 ppm (v/v) for 13 weeks. There was a dose related reduction in water consumption throughout the study at 1000 and 5000 ppm, which is considered to indicate a degree of unpalatability of the drinking water. There was a slight reduction in bodyweight gain in males at 5000 ppm, which was associated with a small reduction in food consumption compared to the controls, but this did not attain statistical significance. There were no toxicologically significant clinical effects and no histopathological changes. The highest no effect level was 5000 ppm vinyl acetate in drinking water, equivalent to an average daily dose level of 684 mg/kg in the male rat and 810 mg/kg in the female rat.