Potential artifacts and misinterpretations when evaluating the ecotoxicological effects of nanomaterials E. J. Petersen, * T. B. Henry **,***,**** , J. Zhao ***** , R. I. MacCuspie, ******,******* T. L. Kirschling, ******** V. Hackley, ****** B. Xing, ***** J. C. White ********** * Biosystems and Biomaterials Division, Materials Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, United States ** School of Life Sciences, Heriot-Watt University, Edinburgh, United Kingdom *** Center for Environmental Biotechnology, University of Tennessee, Knoxville, Tennessee, United States **** Department of Forestry, Wildlife and Fisheries, University of Tennessee, Knoxville, Tennessee, United States ***** Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003, United States ****** Materials Measurement Science Division, Materials Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, United States ******* Nanotechnology Program, Florida Polytechnic University, Lakeland, FL 33801 United States ******** Applied Chemicals and Materials Division, Materials Measurement Laboratory, National Institute of Standards and Technology, Boulder, CO 80305, United States ******** Department of Analytical Chemistry, The Connecticut Agricultural Experiment Station, New Haven, CT 06504, United States ABSTRACT Engineered nanomaterials (ENMs) have significant commercial potential in a broad range of industries for consumer products as a result of their novel properties. However, these same properties may cause unexpected risks once ENMs are released into the environment either intentionally or unintentionally. Thus, standard methods are needed to accurately and reproducibly assess the potential risk of ENMs. One factor that limits the applicability of standard ecotoxicology test methods for use with ENMs is that the unique behaviors of ENMs may cause artifacts or misinterpretations in these tests as a result of their unique behaviors. We briefly discuss these artifacts and misinterpretations and provide an illustrative example. Keywords: nanoparticle, nanoecotoxicology, standard test methods, artifacts, nanomaterials 1 INTRODUCTION Nanotechnology promises exciting innovations in a broad range of fields, and nanomaterials have substantial potential for incorporation into consumer products. Nanomaterials are defined using the definition from the International Organization for Standardization (ISO): engineered nanomaterials (ENMs) are materials with any external dimension between 1 nm and 100 nm or having an internal surface structure in those dimensions [1, 2]; other agencies such as the FDA may not necessarily operate under this strict definition. One issue that has limited the commercialization of ENM-containing products is their potential impacts on humans and the environment. Standard methods are needed for assessing the potential risks of ENMs, but the behaviors of ENMs differ substantially from those of traditional environmental pollutants such as hydrophobic organic chemicals and inorganic pollutants such as lead. Moreover, a literature review of the nanotechnology environmental health and safety literature showed that uncertainty in the applicability of current standard test methods for use with ENMs is the most frequently cited source of uncertainty [3]. One of the substantial differences between the behaviors of traditional environmental pollutants and ENMs during ecotoxicology testing is that ENMs may cause artifacts and misinterpretations during many of these tests. While there have been numerous review articles on the ecotoxicity of ENMs in organisms [4-18], the potential experimental artifacts and misinterpretations during these tests have received substantially less attention. For example, artifacts have been previously observed in nanoecotoxicology testing as a result of an unintended byproduct produced during the ENM dispersion process [19, 20] and from ENM interference with an assay reagent [21-27]. Misinterpretations in nanoecotoxicology testing are also possible if the effect observed is mistakenly attributed to nanoparticles when dissolved ions are actually the cause of the toxic effect. In a recently submitted review article [28], NSTI-Nanotech 2014, www.nsti.org, ISBN 978-1-4822-5830-1 Vol. 3, 2014 123