Regional multimedia distribution of nanomaterials and associated exposures: A software platform Haoyang Haven Liu, Muhammad Bilal, Yoram Cohen Center for the Environmental Implications of Nanotechnology University of California, Los Angeles Los Angeles, CA, USA Anastasiya Lazareva, Arturo Keller Bren School of Environmental Science and Management University of California, Santa Barbara Santa Barbara, CA, USA Abstract— An integrated modeling platform was developed for assessing the potential release rates of ENMs and their environmental distribution. ENM release rates are estimated via life cycle assessment based approach by tracking the target ENM throughout its life cycle from production to release to the environment. Potential ENM exposure concentrations and mass distribution in the various environmental media (i.e., air, water soil, vegetation) are then evaluated via multimedia modeling that considers the environment as a collection of compartments linked by mechanistic intermedia transport processes. A web-based software implementation of the modeling platform enables rapid “what-if?” scenario analysis, which can be used to assess the response of environmental system to various scenarios of ENM releases, investigate the impact of geographical and meteorological parameters on ENM distribution in the environment, compare the impact of ENM production and potential releases on different regions, we well as estimate source release rates based on monitored ENM concentrations. Moreover, the present modeling platform is suitable for research and teaching regarding environmental multimedia impact assessment at both the undergraduate and graduate levels. It is envisioned that the present multimedia analysis platform can assist regulators, industry, and researchers to rapidly and critically assess the potential environmental implications of ENMs and thus ensure that nanotechnology is developed in a productive and environmentally responsible manner. Keywords— environmental exposure assessment, life cycle assessment, engineered nanomaterials, web-based modeling platform I. INTRODUCTION The use of engineered nanomaterials (ENMs) reported in more than 1000 commercial products has a significant impact on both natural environmental and human health [1-3]. In order to ensure responsible and sustainable development of nanotechnology, it is crucial to assess the environmental impact of such technology. In recent years, various environmental impact assessment (EIA) frameworks have been proposed [4], and these frameworks have recognized the need to evaluate the potential environmental distributions of ENMs in addition to their potential toxicological effects. Due to the scarcity of measured environmental concentration of ENMs, as well as lack of suitable measurement techniques, computational modeling approaches have emerged as promising alternatives from various studies to estimate the ENM release rates [5, 6] as well as their concentrations in the environment [7-9]. In order to assess the likely ENMs release rates to the various environmental compartments, life cycle inventory assessment (LCIA) based approaches have been utilized to track the mass of ENM throughout its life cycle from production, through use, to final disposal and release to the environment. The above approaches were based on ENM production rates and a set of transfer coefficients that quantify the fraction of mass transferred between compartments (environmental or technical) [5, 10]. Recently, a mechanistic model for assessing the multimedia environmental distribution of ENMs (MendNano) has been developed [7] which treats the environment as a collection of compartments (i.e., media) that are linked via a series of mechanistically quantified intermedia transport processes, in order to solve for temporally dynamic concentration and mass distribution of ENMs in the environment. MendNano was successfully validated using data for semi-volatile organics, which have a tendency to adsorb onto ambient particles [11, 12] and thus their transport behaviors are governed by the particulate phase as is the case with ENMs [7, 13]. Another simple approach based on the SimpleBox [14] model was recently proposed for nanomaterials (SimpleBox4nano) [9], which estimates both steady state ENM environmental mass concentrations as well as temporal concentration profiles via a first-order kinetics. However, the environment is dynamic [7] and transport processes do not necessarily follow a first order kinetic due to episodic intermedia transport processes such as rain scavenging, which is known to be able to rapidly remove air-borne pollutants (particulate or dissolved) to the terrestrial and aquatic surfaces below [13]. Therefore, assuming first-order kinetics for the purpose of estimating the temporal concentration profiles may introduce significant error. It was claimed that SimpleBox4nano as a compartmental model was an improvement, attributed to the inclusion of heterogeneous agglomeration and attachment process via solution of the Smoluchowski coagulation equation [9]. However, the attachment efficiency parameter used in the above model was in fact obtained empirically and assumed to be constant (i.e., time invariant). This assumption is not mechanistically correct, as the attachment efficiency is a function of particle size, which increases as particles agglomerate. Additionally, SimpleBox4nano only accounts for the average particle size in each of the particle classes (freely suspended ENM, ENM attached to colloids, and ENM attached to larger particles). 2014 IEEE International Conference on Bioinformatics and Biomedicine 978-1-4799-5669-2/14/$31.00 ©2014 IEEE 10