Engineered nanomaterials (ENs) comprise a diverse suite of structures manufactured from a range of distinct components that are having an ever-increasing number of applications in industry, commerce and medicine (Figure 1). ENs reported to be produced in the largest quantities include TiO2, SiO2, ZnO, AlOx, FeOx, silver, carbon nanotubes, fullerenes and quantum dots, at levels ranging from 0.5 – 5,500 tonnes/year worldwide [1]. The negative impact of ENs on the environment and human health due to off-target effects is of major concern and requires ongoing investigation. A recent database (NanoE-Tox), compiled from 224 articles published over the preceding decade, was created in order to obtain an overview of the environmental effects of eight chemically distinct ENs where toxicity toward crustaceans (Daphnia magna), fish, algae or bacteria was the primary readout [2]. The purposes of such databases are to: 1) gain an understanding of the relative toxicities of various ENs and how these relate to their physicochemical properties, 2) decipher the mechanism(s) by which their toxicities occur and, 3) provide an alternative to ethically questionable, time consuming and costly animal studies, through the development of predictive models that derive from these databases. NanoE-Tox reported the most ecotoxic ENs to be made from silver, followed by ZnO and CuO, with the primary mechanism of toxicity of these ENs being dissolution of ions, however, direct cell membrane damage, oxidative stress and genotoxicity were also potentially contributing factors for Ag and ZnO ENs. A lack of sufficient information regarding the various physicochemical parameters (primary size, shape, surface charge, surface area) meant that their contributions to cytotoxicity could not be conclusively defined.
