Differential bioaccumulation patterns of nanosized and dissolved silver in a land snail Achatina fulica

With the increasing application in antimicrobial products, silver nanoparticles (AgNP) are inevitably released into the terrestrial environment, and pose potential risks to invertebrates such as land snails Achatina fulica, which take up AgNP from food and water. Here we differentiate Ag uptake biodynamic between Ag forms (i.e., PVP-AgNP vs. AgNO₃) and between exposure pathways. Snails assimilated Ag efficiently from lettuce leaves pre-exposed to AgNP, with assimilation efficiencies (AEs) averaging 62-85% and food ingestion rates of 0.11 ± 0.03 g g^-1 d^-1. Dietary Ag bioavailability was independent on Ag forms, as revealed by comparable AEs between AgNP and AgNO₃. However, the uptake rate constant from water was much lower for AgNP relative to AgNO₃ (2 × 10^-4 vs. 0.12 L g^-1 d^-1). The elimination rate constants were 0.0093 ± 0.0037 d^-1 for AgNP and 0.019 ± 0.0077 d^-1 for AgNO₃. Biodynamic modeling further showed that dietary exposure was the dominant uptake pathway for AgNP in most circumstances, while for AgNO₃ the relative importance of waterborne and dietary exposure depended on Ag concentrations in food and water. Our findings highlight the importance of dietary uptake of AgNP during bioaccumulation, which should be considered in the risk assessment of these nanoparticles.