Tissue Distribution of Radiolabeled ^110mAg Nanoparticles in Fish: Arctic Charr (Salvelinus alpinus)

This study presents the first whole-body tissue distributions of dissolved (Ag_I) and 20 nm silver nanoparticles (Ag₀NPs₂₀) in fish (Arctic charr, Salvelinus alpinus). The distributions are provided for fish exposed to three different treatments: (i) intravenous (IV), (ii) dietary, and (iii) waterborne. Quantitative whole-body autoradiography (QWBA) analyses obtained on high-resolution images reveal distinct silver distribution patterns according to the treatments. The IV exposures showed that AgNPs₂₀ were mainly located in bile and kidney after 8 d, while Ag_I was distributed through the whole body and reached particular tissues such as bones, eyes, skin, liver, spleen, kidney, and intestine. The Ag₀NPs₂₀ distribution with the dietary exposures suggests that some dissolution occurred within fish organs. We propose that dissolved silver could later precipitate as chloride, sulfide, or selenide and be incorporated in bones during the growth. Consequently, it is yet difficult to state if Ag₀NPs₂₀ cross biological barriers. Finally, the waterborne exposures revealed that the gills can capture Ag₀NPs₂₀, but in small quantities. This suggests that the stability of Ag₀NPs₂₀ in water is critical for the uptake via the gills.