Uptake, tissue distribution, and depuration of total silver in common carp (Cyprinus carpio) after aqueous exposure to silver nanoparticles

The increased use and disposal of silver nanoparticles (AgNPs) has led to their release from wastewater treatment plants into surface waters and concern over potential for negative effects in aquatic organisms. Investigations of the toxicity of AgNPs in fish have considered various species, exposure routes, and test end points; however, the toxicokinetics of total silver has not been studied in fish exposed to aqueous AgNPs. In this study, we investigated the toxicokinetics of total silver in common carp (Cayprinus carpio) exposed to AgNPs [0.62 ± 0.12 (mean ± standard deviation) mg L^-1] for 7 days followed by a 2 week depuration period. During exposure and depuration, fish were sampled, tissues were excised (gills, brain, skeletal muscle, gastrointestinal tract, liver, and blood) and digested in acid, and total silver concentrations were analyzed by inductively coupled plasma-optical emission spectrometry. Total silver in tissues increased during the 7 day exposure, and mean concentrations were 5.61 mg/kg of liver, 3.32 mg/kg of gills, 2.93 mg/kg of gastrointestinal tract, 0.48 mg/kg of skeletal muscle, 0.14 mg/kg of brain, and 0.02 mg/kg of blood. Transmission electron microscopy energy-dispersive spectroscopy confirmed the presence of silver in the tissues. After depuration for 14 days, total silver returned to control levels in all tissues except liver (4.22 mg/kg), gastrointestinal tract (1.26 mg/kg), and gills (0.77 mg/kg).