Engineered nanoparticles are defined as those materials with at least one dimension in the range 1 – 100 nm which are specifically designed and produced by human activity, and do not include nanoparticles which are produced incidentally by human activity or those produced by natural processes. They cover a wide variety of possible morphologies, sizes, specific surface areas and chemistries and can be divided into organic forms such as fullerenes, carbon nanotubes or dendrimers and inorganic forms such as metals, metal oxides, or metal sulfides. They are now of increased concern due to their greater production, release and potential release into the environment and also due to our limited knowledge on their effects on human and ecological health.
According to the recent report by the Royal Society and Royal Academy of Engineering on nanoscience and nanotechnology, 1 billion euros is currently spent in Europe, 3.7 billion US dollars in the USA between 2005-2008 and 800 million USD in Japan in 2003 and this figure is set to increase. For 2005, the worldwide investment in research and development into nanotechnology by national governments was 4100 million USD (Roco, 2005).
Because of the novel arrangements of the atoms in these molecules, nanoparticles display unusual chemical properties, which potentially enable them to perform a wide range of applications. Nanoparticles, engineered as high surface area spheres, rods or other geometries already have a range of industrial uses and are present in cosmetics, stain-proofing, computers and other products. As a consequence, increasing attention has focussed on these engineered nanoparticles, which show potential or actual utility in industry. For instance, field-based studies have been performed on the bioremediation of chlorinated organic compounds in contaminated land (Jia et al, 2005; Schrick et al, 2004; Ponder et al, 2001) usually by zerovalent iron nanoparticles, which may reduce pollutant levels in contaminated land but will also result in large direct release into the environment. Although substantial reduction in contaminants has been reported in these studies, there has also been concomitant reduction of oxygen levels resulting in a change from aerobic to anaerobic conditions (Zhang, 2003).
In addition, engineered nanoparticles are known to be transported rapidly in porous media (Lecoanet and Wiesner, 2004) The properties of nanoparticles which make them useful in manufacturing, also make them potentially biologically disruptive and the potential health risks associated with exposure to nanoparticles are now of international concern. Significant and severe human health effects have been shown to lung and skin tissue (Jia et al, 2005; Colvin, 2003, Hoet et al., 2004; Shvedova et al., 2003 Klot et al., 2002) as well as damage in other mammals (Bermudez et al., 2004, Chen et al., 1997).
However, with few exceptions, essentially nothing is known about the potential health impacts of synthetic nanoparticles in the aquatic environment. However, (Oberdorster, 2004) showed that fullerenes cause lipid oxidation in the brain tissue of large mouth bass, while Fortner et al (2005) and Lyon et al (2006) showed damage from aqueous suspensions of fullerene aggregates to both gram negative and positive bacteria relevant in aquatic systems.
In addition, to our knowledge, little is known about the fate or behaviour of manufactured nanoparticles in the aquatic environment. In the report by the RS/RAE, already mentioned, which was commissioned by the UK government it was concluded: ‘Until more is known about environmental impacts of nanoparticles and nanotubes, we recommend that the release of manufactured nanoparticles and nanotubes into the environment be avoided as far as possible’. These issues are now in the process of being addressed by the research, regulatory and industrial community. As such the development of a knowledge transfer network in this area is timely and will have clear beneficial effects on our current and future understanding.
