Toxicokinetic Differences and Toxicities of Silver Nanoparticles and Silver Ions in Rats After Single Oral Administration

Blood levels, tissue distributions, and excretion of silver (Ag) were measured in male Sprague-Dawley rats (n = 5) up to 24 h after a single oral administration of silver nanoparticles (AgNP) and silver ions (Ag(+)), respectively. The AUC24hr of Ag(+) was 3.81 ± 0.57 μg/d/ml when rats were treated with a single dose of 20 mg/kg, whereas that of AgNP was 1.58 ± 0.25 μg/d/ml. Tissue distribution of Ag in liver, kidneys, and lungs was higher when Ag(+) was administered compared to AgNP. Orally administered AgNP were predominantly excreted through feces, suggesting low bioavailability. Death or body weight changes were not observed in the Ag(+)- or AgNP-treated groups. However, decreased red blood cell counts, hematocrit, and hemoglobin were found in the Ag(+)-treated groups, while increased platelet counts and mean platelet volume were noted in the AgNP-treated rats. A serum biochemical analysis showed that aspartate aminotransferase (AST) and alanine aminotransferase (ALT) rose significantly following Ag(+) treatment (20 mg/kg). AgNP treatment (2 or 20 mg/kg) also elevated AST, whereas infiltration of mononuclear cells with liver necrosis was found only in the 20 mg/kg Ag(+)-treated animals.