An analysis of engineered nanomaterial characteristics reported in aquatic nanotoxicity studies: 2004-2013

Abstract

In this study, we employed bibliometric techniques to analyse engineered nanomaterials (ENMs) characterization data published in peer-reviewed aquatic nanoecotoxicity hosted in the International Council on Nanotechnology (ICON) and Web of Science databases. Findings reported herein are based on 192 peer reviewed studies from January 2004 to March 2013. From the studies we examined: (1) the extent of reported characterisation properties of ENMs and testing media characteristics in the study data, and (2) the utilisation or application of ENMs characterisation data within a specific study to account for the observed toxicity response on biota. The most reported ENM characteristic was size by 99% of the studies, and surface coating was the least at 30% (Fig. 1). The low reporting of surface area and surface charge by 35% and 34%, respectively, suggests poor understanding on their influence towards reported toxicity. Large percentage of the particle size analysis was undertaken in testing media, rather than relying on data supplied by manufacturers, and suggests a high proportion of the data being credible and scenario relevant. The TEM was the most used technique for size characterisation at 69% (Fig. 2) possibly because it also generates morphology and surface composition characteristics data. Use of more than one size analysis techniques was observed, and hence contributed towards generation of high quality data. The testing media characteristics were poorly reported in the studies as pH, ionic strength, and natural organic matter were reported by 59%, 17%, and 12%, respectively, and need to be improved. Our analysis indicated the effort by the researchers to utilise ENMs characterisation data to a certain degree to account for the observed toxicological responses. Overall, our findings indicates that for future nanoecotoxicity studies, both inherent ENMs characteristics and media chemistry properties should be reported to improve our collective understanding.