Ecotoxicity of silver nanomaterials in the aquatic environment: A review of literature and gaps in nano-toxicological research

Abstract

There has been extensive growth in nanoscale technology in the last few decades to such a degree that nanomaterials (NMs) have become a constituent in a wide range of commercial and domestic products. With NMs already in use in several consumer products, concerns have emerged regarding their potential adverse environmental impacts. Although research has been undertaken in order to minimise the gaps in our understanding of NMs in the environment, little is known about their bioavailability and toxicity in the aquatic environment. Nano-toxicology is defined as the study of the toxicity of nanomaterials. Nano-toxicology studies remain poorly and unevenly distributed. To date most of the research undertaken has been restricted to a narrow range of test species such as daphnids. Crabs are bio-indicators that can be used for toxicological research on NMs since they occupy a significant position in the aquatic food chain. In addition, they are often used in conventional ecotoxicological studies due to their high sensitivity to environmental stressors and are abundantly available. Because they are benthic organisms they are prone to contaminant uptake and bioaccumulation. To our knowledge the crab has never been used in nano-toxicological studies. In this context, an extensive review on published scientific literature on the ecotoxicity of silver NPs (AgNPs) on aquatic organisms was conducted. Some of the most common biomarkers used in ecotoxicological studies are described. Emphasis is placed on the use of biomarker responses in crabs as monitoring tools, as well as on its limitations. Additionally, the gaps in nano-toxicological research and recommendations for future research initiatives are addressed.

Ag Nanoparticles/AgX (X=Cl, Br and I) Composites with Enhanced Photocatalytic Activity and Low Toxicological Effects

“…As shown in previous work, some material characteristics, such as the particle sizes, morphology, and solubility, may be the main causes of the different forms of interaction with biological molecules, such as membrane proteins and genetic material. For this purpose, the toxicity of some materials has mainly been related to the dispersion capacity of Ag nanoparticles in an aquatic environment because at low doses, Ag nanoparticles can exhibit algicidal, fungicidal, and bactericidal properties . In our study, the AgCl, AgBr and AgI samples were tested because their widespread use by industry and discharge into the environment may have an impact on a wide variety of aquatic organisms as well as human health …”

Repeated dose (28-day) administration of silver nanoparticles of varied size and coating does not significantly alter the indigenous murine gut microbiome

“…Sequences were aligned to a SILVA alignment database using the Needleman–Wunsch and NAST algorithms, and sequences that did not share a defined alignment space were trimmed (Schloss et al, 2011, Schloss, 2010, Schloss, 2009). Chimeras were removed using the UCHIME algorithm (Walters et al, 2014). The Ribosomal Database Project (RDP) naive Bayesian classifier within mothur was used to taxonomically assign 16S rRNA gene sequences, using a confidence cutoff of 80%.…”

Assessing environmental pollution in birds: a new methodological approach for interpreting bioaccumulation of trace elements in feather shafts using geochemical sediment data

“…; Hamilton ; Cempel & Nikel ; Stern ; Tchounwou et al . ; Walters, Pool & Somerset ; Herrmann et al . ).…”

“…We chose to analyse 14 elements in both sediments and feathers. Ten elements were chosen because of environmental concern: As, Cd, Cr, Cu, Hg, Ni, Pb, Se, Sn and Zn (ATSDR 1994;Hamasaki et al 1995;Hamilton 2004;Cempel & Nikel 2006;Stern 2010;Tchounwou et al 2012;Walters, Pool & Somerset 2014;Herrmann et al 2016). Aluminium, Fe, K and La were chosen as indicators of clay and the finest fraction of sediment (Leeder 1982).…”