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Issues in Assessing Environmental Exposures to Manufactured Nanomaterials
U.S. EPA/ORD/NERL/ERD, 960 College Station Road, Athens, GA 30605, USA
CNA, 4825 Mark Center Drive, Alexandria, VA 22311, USA
Department of Crop and Soil Sciences, University of Georgia, Athens, GA 30602, USA
* Author to whom correspondence should be addressed.
Received: 2 April 2011; in revised form: 15 August 2011 / Accepted: 17 August 2011 / Published: 31 August 2011
Abstract: Manufactured nanomaterials (MNs) are commonly considered to be commercial products possessing at least one dimension in the size range of 10−9 m to 10−7 m. As particles in this size range represent the smaller fraction of colloidal particles characterized by dimensions of 10−9 m to 10−6 m, they differ from both molecular species and bulk particulate matter in the sense that they are unlikely to exhibit significant settling under normal gravitational conditions and they are also likely to exhibit significantly diminished diffusivities (when compared to truly dissolved species) in environmental media. As air/water, air/soil, and water/soil intermedium transport is governed by diffusive processes in the absence of significant gravitational and inertial impaction processes in environmental systems, models of MN environmental intermedium transport behavior will likely require an emphasis on kinetic approaches. This review focuses on the likely environmental fate and transport of MNs in atmospheric and aquatic systems. Should significant atmospheric MNs emission occur, previous observations suggest that MNs may likely exhibit an atmospheric residence time of ten to twenty days. Moreover, while atmospheric MN aggregates in a size range of 10−7 m to 10−6 m will likely be most mobile, they are least likely to deposit in the human respiratory system. An examination of various procedures including the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory of colloidal particle suspension stability in water indicates that more sophisticated approaches may be necessary in order to develop aquatic exposure models of acceptable uncertainty. In addition, concepts such as Critical Coagulation Concentrations and Critical Zeta Potentials may prove to be quite useful in environmental aquatic exposure assessments.
Keywords: manufactured nanomaterials; atmospheric emissions; aquatic emissions; ultrafine particles; DLVO theory; zeta potential; Critical Coagulation Concentration
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MDPI and ACS Style
Loux, N.T.; Su, Y.S.; Hassan, S.M. Issues in Assessing Environmental Exposures to Manufactured Nanomaterials. Int. J. Environ. Res. Public Health 2011, 8, 3562-3578.
Loux NT, Su YS, Hassan SM. Issues in Assessing Environmental Exposures to Manufactured Nanomaterials. International Journal of Environmental Research and Public Health. 2011; 8(9):3562-3578.
Loux, Nicholas T.; Su, Yee San; Hassan, Sayed M. 2011. "Issues in Assessing Environmental Exposures to Manufactured Nanomaterials." Int. J. Environ. Res. Public Health 8, no. 9: 3562-3578.