Evaluating engineered nanoparticles in natural waters

With the accelerating introduction of engineered nanomaterials into commercial products and their potential use in water-treatment processes, it is inevitable that these materials will ultimately reside at some level in our recreational and drinking waters, thereby creating a critical need to detect and to quantify them in those media. Much is known about the diversity of engineered nanoparticles (ENPs) in the environment but almost nothing about their characterization and detection in the natural aquatic environment. There is no conventional treatment that can absolutely protect the consumer from exposure to ENPs either through recreational use or consumption of drinking waters. The question is whether this exposure poses a significant public health risk. Unfortunately, we are far from having methods to obtain data on occurrence levels, fate, and transport of ENPs in aquatic systems. Before a sound analytical approach can be developed, we need a fuller understanding of the nanomaterial domain which requires an evaluation of the matrix of source materials, their transformation in the natural aquatic environment, and their physical/chemical behavior that is specific to the water medium. We review characterization techniques that are used for identifying different types of ENP, and then, by extrapolation from isolation techniques appropriate for extracting ENPs from water, suggest approaches to analyzing them in a variety of waters. (C) 2010 Elsevier Ltd. All rights reserved.