Pilot Estuarine Mesocosm Study on the Environmental Fate of Silver Nanomaterials Leached from Consumer Products

D. Cleveland, S.E. Long, P.L. Pennington, E. Cooper, M.H. Fulton, G.I. Scott, T. Brewer, J. Davis, E.J. Petersen, L. Wood
National Institute of Standards and Technology, US

Keywords: mescosm, silver nanoparticle, accumulation, toxicity

Summary:

Although nanosilver consumer products (CPs) enjoy widespread availability, the environmental fate, leaching, and bioaccumulation behaviors of silver nanoparticles (AgNPs) from these products are not well understood. In this work, three nanosilver CPs and two AgNP standards, and an ionic silver (Ag+) standard were studied in estuarine mesocosms. The CPs exhibited long-term release of significant amounts of silver over a 2 month residence time in the mesocosms, and ultimately released 82 - 99 % of their total silver loads. Measurements of total silver as a function of time indicated that the leached silver was transferred from the water column and accumulated in the estuarine biota. Total clam mortality was observed only for clams treated with Ag+, even though the AgNP standards were added at the same concentration as the Ag+ standard, and the CPs leached total silver concentrations that were significantly higher than the concentrations of the standards. Clams treated with a 20 nm AgNP standard exhibited signs of toxicity only after 2 months of exposure. These results suggested that AgNPs may have less pronounced effects on estuarine environments compared to Ag+.