Bioaccumulation and toxicity of silver compounds: A review

Abstract

A eview of the literature revealed that bioaccumulation of silver in soil is rather low, even if the soil is amended with silver‐containing sewage sludge. Plants grown on tailings of silver mines were found to have silver primarily in the root systems. In marine and freshwater systems, the highest reported bioconcentration factors (BCFs) were observed in algae (>105), probably because of adsorption of the dissolved silver (<0.45 μm fraction) to the cell surface. In herbivorous organisms (e.g., zooplankton and bivalves), the BCF was lower by about two orders of magnitude. Low amounts of silver were assimilated from food with no substantial biomagnification. In carnivores (e.g., fish), the BCF was also lower by one order of magnitude with no indication of biomagnification. Toxicity of silver occurs mainly in the aqueous phase and depends on the concentration of active, free Ag+ ions. Accordingly, many processes and water characteristics reduce silver toxicity by stopping the formation of free Ag+, binding Ag+, or preventing binding of Ag+ to the reactive surfaces of organisms. The solubility of a silver compound, and the presence of complexing agents (e.g., thiosulfate or chloride), dissolved organic carbon, and competing ions are important. In soil, sewage sludge, and sediments, in which silver sulfide predominates, the toxicity of silver, even at high total concentrations, is very low. The highly soluble silver thiosulfate complex has low toxicity, which can be attributed to the silver complexed by thiosulfate. Silver nitrate is one of the most toxic silver compounds. The toxic potential of silver chloride complexes in seawater is and will be an important issue for investigation. Aquatic chronic tests, long‐term tests, and tests including sensitive life stages show lower toxicity thresholds (˜1 μg Ag+/L). The organisms viewed as most sensitive to silver are small aquatic invertebrates, particularly embryonic and larval stages.

Biogeochemical Cycling of Silver in Acidic, Weathering Environments

“…Furthermore, it is reasonable to suggest that the lower-range values could reflect seasonal variations in precipitation [75] whereas higher-range values could represent the extent to which Ag biogeochemical cycling occurs within the respective regolith material. In terms of environmental reclamation, historical mining practices have left behind a legacy that pose a risk of silver contamination and toxicological effects on the surrounding environment [76,77]. This contamination can be attributed, in part, to inefficient methods of extraction based on today's standards [78].…”

New views on cellular uptake and trafficking of manufactured nanoparticles

“…The release of molecular debris and/or metal ions (e.g. Ag, Cd or In) will give rise to cytotoxic effects [58][59][60]. Adverse effects of NP incorporation will generally be a combination of ionic/molecular toxicity and toxicity aspects related to the particulate nature of the material.…”

A method to determine silver partitioning and lability in soils

“…The presence of Ag in the environment is of concern because of its potential toxicity to a range of organisms such as plants, invertebrates, microbes and bacteria living in the soil. [12][13][14][15][16] In comparison to aquatic environments, there has been limited research undertaken on the fate and behaviour of Ag in soil. The predicted increase in Ag concentrations (e.g.…”