Tissue distribution of ionic and nanoparticulate silver in newly hatched chicks after egg-injection exposure

Silver nanoparticles (AgNPs) and ionic silver have attracted growing attention owing to their potential ecotoxicity. However, information regarding their transgenerational transfer in terrestrial animals remains scarce. In this study, the tissue distribution of ionic silver and AgNPs were investigated in newly hatched chicks after egg-injection exposure. Tissue-specific distribution was observed in hatchlings, and yolk sac contained the highest concentration of total silver. The lowest total silver concentration was found in the heart in both the silver ion and 20-nm AgNPs groups, and the kidneys in the 100-nm AgNPs group. Total silver concentrations in most tissues in the 20-nm AgNPs group were higher than those in silver ion and 100-nm groups, indicating the highest migration efficiency. The concentration of AgNPs in the 20-nm group also exceeded that in the 100-nm group across most tissues. Our findings were consistent with previous reports regarding silver tissue distribution after oral exposure, primarily accumulating in digestion-related tissues (the liver in particular). However, the kidneys also showed high accumulation after oral ionic silver exposure. Given the limited available information on maternal exposure, further studies are required to elucidate the transgenerational transfer and the associated potential risks of AgNPs in terrestrial animals.