Biodistribution and toxicity of antimicrobial ionic silver (Ag+) and silver nanoparticle (AgNP+) species after oral exposure, in Sprague-Dawley rats.

Although antimicrobial nanosilver finds numerous applications in the health and food industries, the in vivo toxicity of positively charged silver nanoparticles (AgNPs+) and relevant controls are largely unexplored. This study investigates the relationship between the biodistribution and toxicity of the well-known cetyltrimethylammonium bromide (CTAB)-capped AgNPs+ in 6-weeks old female Sprague-Dawley rats, at sublethal doses. Amounts comparative to those leaked from food products or considered for animal feed were administered through daily water intake, for an 18-day period: AgNPs+ (40 μg mL−1), Ag+ (40 μg mL−1), antimicrobial CTAB+ (24 μg mL−1) and tap water. All exposures except for the water control had adverse effects on the health and systemic functions of rats (e.g. , lethargy, hepatomegaly, splenomegaly, impediment of bone development, and/or heightened immune response). Although the total Ag accumulation in tissues (1.4–1.6 μg of Ag/g of liver, spleen, jejunum, and brain) was comparable for the two Ag species, AgNPs+ were generally more toxic than Ag+, particularly in spleen (0.8 μg Ag/g). Significantly reduced euthanasia time, alopecia, inflammatory responses in spleen, fragile veins, and enhanced lymphocytosis were observed only for AgNPs+. Overall, this study raises health concerns about the ingestion of capped-AgNPs+ or Ag+ by first-hand consumers and industry workers. [Display omitted] • Adverse effects of silver nanoparticles, capping agents, and silver ions on the health of Sprague-Dawley rats. • Lethargy, hepatomegaly, splenomegaly, impediment of bone development, and/or heightened immune response. • Exposure through water intake, in amounts comparable to those leaked from food products or considered for animal feed. • Total silver accumulation in liver, spleen, jejunum, and brain comparable for the two silver species. • Positively charged silver nanoparticles generally more toxic than the silver ions, particularly in spleen. [ABSTRACT FROM AUTHOR]