Eight-five day postexposure follow-up study in Fischer 344 rats after repeated exposures to methyl isocyanate vapor
The objectives of this study were to describe the microscopic lesions in the respiratory tract of Fischer 344 rats as a result of 4- or 8-days exposure (6 hr/day) of 3 ppm MIC and to characterize the postexposure development of these lesions up to day 85. All rats survived the exposure regimen, although significant decreases in body weight and encrustation of the eyes, nose, or mouth were observed. During the first 15 days of postexposure, the rats were hypoactive and had increased respiratory rates. Male mortality was as high as 63%; only 5% of the MIC-exposed females died. The cause of death was interpreted to be respiratory compromise complicated by anorexia and probably dehydration as well. During the next 28 postexposure days, 48% of the male survivors died, while only 3% of the female survivors died. Throughout the 85-day postexposure period, body weight gains in the MIC-treated groups were consistently below control values. Inflammatory and squamous metaplastic lesions of the respiratory tract, observed the day following completion of either the 4- or 8-day exposure regimen, decreased in both frequency and/or severity in survivors of the 85-day postexposure period, indicating recovery from the cytotoxic and irritating effects of MIC vapor. The squamous metaplastic epithelium was replaced by regenerative epithelium beginning in the deeper portion of the respiratory tract. Maturation of collagen occurred in the areas of submucosal fibroplasia.
- Research Organization:
- Union Carbide Corp., Export, PA
- OSTI ID:
- 5898128
- Journal Information:
- Environ. Health Perspect.; (United States), Journal Name: Environ. Health Perspect.; (United States) Vol. 72; ISSN EVHPA
- Country of Publication:
- United States
- Language:
- English
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63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ANIMAL TISSUES
ANIMALS
BIOLOGICAL EFFECTS
BIOLOGICAL RECOVERY
BIOLOGICAL REGENERATION
BODY
BODY AREAS
COLLAGEN
EPITHELIUM
EYES
FACE
FEMALES
FLUIDS
GASES
HEAD
INFLAMMATION
INHALATION
INTAKE
ISOCYANATES
MALES
MAMMALS
MORTALITY
NOSE
ORGANIC COMPOUNDS
ORGANS
PATHOLOGICAL CHANGES
PROTEINS
RATS
RECOVERY
RESPIRATORY SYSTEM
RODENTS
SCLEROPROTEINS
SENSE ORGANS
SYMPTOMS
TISSUES
VAPORS
VERTEBRATES
WEIGHT