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 cetyl-trimethylammonium 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 mu g mL(-1)), Ag+ (40 ug mL(-1)), antimicrobial CTAB(+) (24 mu g 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 mu g 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 mu g 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.

Automated summary

This study investigates the relationship between the biodistribution and toxicity of positively charged silver nanoparticles (AgNPs(+)) and finds that they have adverse effects on the health and systemic functions of rats, especially in spleen.