Comparison of acute inhalation toxicity of sulfuric acid by the inhalationand intratracheal instillation methods

摘要

Recently, intratracheal instillation has been focused on as a simple, low-costalternative to the inhalation method. In this study, intratracheal instillation ofsulfuric acid, a typical acidic compound, was performed to compare the acute toxicity ofacidic compounds that could cause damage to the respiratory system between intratrachealinstillation and inhalation. Sulfuric acid was administered to male rats at doses of 0.7,2, 7, 20, and 60 mg/kg by dividing the total dose into four doses. General condition andbody weight were examined up to 14 days after administration, and macropathological andhistopathological examinations were performed. The half-lethal dose was then estimated.All animals administered 20 and 60 mg/kg sulfuric acid and one animal administered 2 mg/kgsulfuric acid died within 4 h after administration. No abnormalities were observed inother animals. At 20 and 60 mg/kg, multiple red foci or diffuse red areas weremacroscopically observed in the lungs. In these lesions, histopathologically, cleftsbetween the mucosal epithelium and basement membrane and necrosis of the alveolarepithelium were observed. Deaths in these groups may have resulted from lung injury. Nonotable changes were observed in other animals. Therefore, the half-lethal dose ofsulfuric acid by intratracheal instillation was estimated as 7–20 mg/kg. The acutetoxicity by intratracheal instillation was evaluated with two-fold sensitivity since theexposure at the half-lethal sulfuric acid concentration in inhalation studies wascalculated as 43.2 mg/kg.