Sublethal pulmonary toxicity screening of silica nanoparticles in rats after direct intratracheal instillation.

Abstract

The present aimed to characterize the toxicity of silica nanoparticles in Sprague Dawley rats and determine the dose levels for a repeated-dose toxicity study. Silica nanoparticles (SiO2, 20nm and 50nm) were administered as a single intratracheal instillation of standardized SiO2 20nm (low dose, 200µg/mL; high dose, 400µg/mL) and 50nm (low dose, 200µg/mL; high dose, 400µg/mL). Each group consisted of five male rats. We documented the mortality rate, clinical signs, body weight, bronchoalveolar lavage fluid analysis, hematological values, serum chemistry values, organ weight, gross findings at necropsy, and histopathological assessments. Rats treated with 200µg/mL and 400µg/mL SiO2 50nm exhibited a decreased mean corpuscular volume, while those treated with 400µg/mL of SiO2 50nm showed increases in absolute monocyte and absolute lymphocyte count as well as prothrombin time. In addition, rats treated with 400µg/mL SiO2 20nm and 50nm presented reduced creatinine, alanine aminotransferase, and sodium levels. Therefore, a single intratracheal instillation of SiO2 20nm and 50nm elicited no toxicity up to a dose of 400µg/mL, and the approximate lethal dose of this test substance exceeded 400µg/mL in male Sprague Dawley rats under the present experimental conditions.