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Toxicological information

Repeated dose toxicity: inhalation

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Administrative data

Endpoint:
chronic toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Non-GLP non-guideline study, published in peer-reviewed literature, minor restrictions in design and reporting, but otherwise adequate for assessment.

Data source

Reference
Reference Type:
publication
Title:
Inhalation toxicity of vinyl chloride and vinylidene chloride.
Author:
Lee CC, Bhandari JC, Winston JM, House WB, Peters PJ, Dixon RL, Woods JS
Year:
1977
Bibliographic source:
Environ Health Perspect 21:25-32.

Materials and methods

Principles of method if other than guideline:
12 months whole-body inhalation exposure of rats to vinyl chloride
GLP compliance:
no
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
Chloroethylene
EC Number:
200-831-0
EC Name:
Chloroethylene
Cas Number:
75-01-4
Molecular formula:
C2H3Cl
IUPAC Name:
chloroethene
Details on test material:
- Name of test material (as cited in study report): vinyl chloride (VC)
- Physical state: gaseous
- Analytical purity: 99.8%
- Supplier: Matheson Products

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 Breeding Lab
- Age at study initiation: about 2 months
- Housing: 2 per cage, in stainless steel cages with wire bottoms
- Diet: pulverized or block laboratory chow (Wayne Manufacturing Company), ad libitum, except during exposure
- Water: ad libitum

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 24 +/- 1.3 C
- Humidity (%): 25-60% at the start of the experiment, later regulated at 50 +/- 10%
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
inhalation
Type of inhalation exposure:
whole body
Vehicle:
other: unchanged (no vehicle)
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: cubical inhalation chamber, made of stainless steel
- Method of holding animals in test chamber: caged
- Volume: 3.5 m3
- VC was metered with rotameters into the chamber air supply

TEST ATMOSPHERE
- Brief description of analytical method used: initially chamber air was sampled with a syringe and monitored using a gas chromatograph (Varian-2700) with a flame ionization detector. An automatic sampling system was later used. Periodically, a sample was directed to the gas chromatograph and the readout was processed by a Varian CDS 111 electronic integrator. The integrator was programmed to measure peak area and to calculate chamber concentrations by external standards.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Initially chamber air was sampled with a syringe and monitored using a gas chromatograph (Varian-2700) with a flame ionization detector. An automatic sampling system was later used. Periodically, a sample was directed to the gas chromatograph and the readout was processed by a Varian CDS 111 electronic integrator. The integrator was programmed to measure peak area and to calculate chamber concentrations by external standards.
Duration of treatment / exposure:
12 months
Frequency of treatment:
6 h/d, 5 d/wk
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 50 ppm, 250 ppm, 1000 ppm
Basis:
nominal conc.
No. of animals per sex per dose:
36/sex/dose
Control animals:
yes
Details on study design:
- Section schedule rationale (if not random): four animals of wach exposure level were terminated for various laboratory tests, gross and histopatologic examinations at the end of 1, 2, 3, 6 and 9 months; the surviving animals were terminated at the end of 12 months.

Examinations

Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS:
- All animals were observed throughout the study for adverse signs.

BODY WEIGHT:
- Body weights were measured biweekly at a uniform time of day.

FOOD CONSUMPTION:
- Food consumption was measured weekly at a uniform time of day.

HAEMATOLOGY:
- RBC, reticulocyte, platelet, WBC and differential countsm, nucleated RBC, hematocrit, hemoglobin, methemoglovin and Heinz bodies were determined in aortic blood from four males and four female of each group at interim and final terminations.

CLINICAL CHEMISTRY:
- Clinical blood chemistry (SGPT and BUN), as well as prothrombin time, SGOT, alkaline phosphatase, bilirubin, creatinine, LDH, alpha-HBDH, immunoglobin IgA, IgB-A, IgB-B and IgM, total protein, albumin, glubolun (by difference) and collagen contents in liver and lung were determined on samples from four males and four female of each group at interim and final terminations.

Sacrifice and pathology:
GROSS PATHOLOGY:
- Gross examination, especially for any appearance of abnormal growth or other lesions, was carefully performed on all tissues including the brain, pituitary, thyroids, respiratory tract, alimentary canal, urogenital organs, thymus, heart, liver, pancrease, spleen, mesenteric lymph nodes, and body cavities. The brain, liver, kidneys, spleen and gonads were removed and weighed.

HISTOPATHOLOGY:
- Tumors with adjacent normal tissues and the whole or portions of the various tissues were fixed, processed, sectioned, and stained for microscopic examination. All external and internal tumors were carefully examined and identified histologically.
Other examinations:
Macrophage counts of pulmonary washings and cytogenic analysis of bone marrow cultures were performed on the control and abunaks receiving 1000 ppm VC. Limbs from the longest exposed animals were examined for osteoporosis or malacia using a senograph X-ray machine. They were examined for the presence of any bone tumors, any changes in bone density, cortical thickness or striations within the bone cortex, any loss of bone cortex, or any unusually trabecular pattern of the bone. Other specific studies including 14C-thymidine incorporation into DNA, hepatic aminolevulinic acid (ALA) synthetase, urinary ALA assays and alpha-fetoprotein were performed as well.

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):
not specified
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
no effects observed
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
not specified
Gross pathological findings:
effects observed, treatment-related
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Histopathological findings: neoplastic:
effects observed, treatment-related
Details on results:
CLINICAL SIGNS AND MORTALITY
No remarkable adverse signs were seen in any rats during the first 7 months. Two females exposed to 50 ppm, 4 males and 10 females exposed to 250 ppm, and 8 males and 13 females exposed to 1000 ppm died or were terminated between 8 and 12 months due to moribund appearance. No deaths occurred in controls.

BODY WEIGHT AND WEIGHT GAIN
Body weights of animals exposed to 50 or 250 ppm were not significantly different from controls throughout the study. The body weights of females exposed to 1000 ppm were less than controls after 4 weeks.

HAEMATOLOGY
No significant differences in hematology were noted between animals exposed to vinyl chloride or controls.

CLINICAL CHEMISTRY
No significant differences in clinical blood chemistry, collagen in liver and lung, urinary ALA level, serum ALA synthetase and serum alpha-fetoprotein were found between animals exposed to vinyl chloride or controls.

GROSS PATHOLOGY:
Hepatic and/or pulmonary hemangiosarcoma occurred in rats exposed to 250 or 1000 ppm of VC during the ninth through the 12th months; the incidence increased with increases in VC levels and length of exposure. Most of these rats died or were terminated ahead of schedule. The rats with hepatic hemangiosarcoma usually developed pulmonary hemangiosarcoma. In addition, hemangiosarcoma occasionally occurred in other tissues including omentum, mesentery, or subcutaneous tissue of rats exposed to 50, 250 or 1000 ppm VC. Hemangiosarcoma was not found in the liver, lung or any other organs of any control rats.
A few other tumors occasionally occurred in one or several rats. The tumors included a small nodule of bronchiolo-aleolar adenoma; reticulo-entothelial cell carcinoma or hepatoma in the liver; ductular adenocarcinoma or fibroadenoma in the mammary gland of the female; malignant lymphoma in the spleen or other organs adenoma in the kidney; squamous cell carcinoma, keratoacanthoma or fibroma in the skin; adenocarcinoma in the sebaceous gland, and chromophobe cell adenoma in the pituitary. These occasional tumors were not related to VC treatment.
OTHER FINDINGS:
A few controls and a few rats treated with VC showed a focal disseminate vacuolization, probably fatty change in livers.

Effect levels

Dose descriptor:
LOAEC
Effect level:
50 ppm
Sex:
male/female
Basis for effect level:
other: Increased mortality at all dose levels

Target system / organ toxicity

Critical effects observed:
not specified

Any other information on results incl. tables

Table 1. Tumor incidence in rats exposed to vinyl chloride for 12 months.

Tumor incidence*

0

50

250

1000

Male

Female

Male

Female

Male

Female

Male

Female

Liver hemangiosarcoma

0/35

0/35

0/36

0/36

2/36

10a/34

6/34

15a,b/36

Lung hemangiosarcoma

0/35

0/35

0/36

0/36

0/36

3/34

4/34

9a/36

Hemangiosarcoma in other organs

0/35

0/35

1/36

1/36

2/36

0/34

0/34

1/36

 

* Total incidence in 12 months

aSignificantly different from incidence in control group by Fischer exact probability test (Siegel, 1956), p<0.05

bSignificantly different from incidence in opposite sex exposed to the same concentration by Fisher exact probability test (Siegel, 1956), p< 0.05

Applicant's summary and conclusion