Acute and subacute toxicity study of inhaled methyl isocyanate in Charles Foster rats

Charles Foster male and female rats were exposed only once to 3.52 and 35.32 ppm doses of methyl isocyanate in separate experiments for 10 min each in an acute toxicity study, while in subacute toxicity experiments, they were exposed to 0.212, 0.265, and 0.349 ppm doses for 30 min daily, for 6 days, by inhalation. Clinical signs, mortality, body and organ weights, and changes in hematology and clinical pathology were routinely monitored to determine the principal organ sites damaged on exposure to the gas. During exposure, animals were observed to have congestion in eyes, lachrymation, nasal secretion and dyspnea, progressively increasing ataxia, and immobility. Uncoordinated movements were also observed, indicating effects on the nervous system. Upon microscopic examination of the viscera, pathological findings confined to bronchial tree, lung parenchyma, liver, and kidneys were observed.