Repeated-dose toxicity and inflammatory responses in mice by oral administration of silver nanoparticles

Toxicity of nanoparticles depends on many factors including size, shape, chemical composition, surface area, surface charge, and others. In this study, we compared the toxicity of different sized-silver nanoparticles (AgNPs) which are being widely used in consumer products due to its unique antimicrobial activity. When mice were treated with AgNPs 1mg/kg for 14 days by oral administration, small-sized AgNPs (22nm, 42nm, and 71nm) were distributed to the organs including brain, lung, liver, kidney, and testis while large-sized AgNPs (323nm) were not detected in those tissues. The levels of TGF-β in serum were also significantly increased in the treated group of small-sized AgNPs but not in large-sized AgNPs. In addition, B cell distribution was increased in small-sized AgNPs but not in large-sized-AgNPs by the phenotype analysis. However, body weight or in the ratio of organ/body weight were not different between the control group and all the AgNPs-treated groups. The repeated-dose toxicity of AgNPs (42nm) was also investigated in mice by oral administration for 28 days. By the administration of AgNPs (0.25mg/kg, 0.50mg/kg, 1.00mg/kg), adverse impacts on liver and kidney were observed in a high dose-treated group (1.00mg/kg), when determined by blood chemistry and histipathological analysis. Cytokines including IL-1, IL-6, IL-4, IL-10, IL-12, and TGF-β were also increased in a dose-dependent manner by repeated oral administration. In addition, B cell distribution in lymphocyte and IgE production were increased. Based on these results, it is suggested that repeated oral administration of nano-sized AgNPs may cause organ toxicity and inflammatory responses in mice.