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iSTREEM ® : An approach for broad‐scale in‐stream exposure assessment of “down‐the‐drain” chemicals
Author(s) -
Kapo Katherine E,
DeLeo Paul C,
Vamshi Raghu,
Holmes Christopher M,
Ferrer Darci,
Dyer Scott D,
Wang Xinhao,
WhiteHull Charlotte
Publication year - 2016
Publication title -
integrated environmental assessment and management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.665
H-Index - 57
eISSN - 1551-3793
pISSN - 1551-3777
DOI - 10.1002/ieam.1793
Subject(s) - context (archaeology) , percentile , environmental science , effluent , streams , flow conditions , scale (ratio) , exposure assessment , hydrology (agriculture) , flow (mathematics) , environmental engineering , computer science , statistics , mathematics , engineering , geography , cartography , computer network , geometry , archaeology , geotechnical engineering
The “in‐stream exposure model” iSTREEM ® , a Web‐based model made freely available to the public by the American Cleaning Institute, provides a means to estimate concentrations of “down‐the‐drain” chemicals in effluent, receiving waters, and drinking water intakes across national and regional scales under mean annual and low‐flow conditions. We provide an overview of the evolution and utility of the iSTREEM model as a screening‐level risk assessment tool relevant for down‐the‐drain products. The spatial nature of the model, integrating point locations of facilities along a hydrologic network, provides a powerful framework to assess environmental exposure and risk in a spatial context. A case study compared national distributions of modeled concentrations of the fragrance 1,3,4,6,7,8‐Hexahydro‐4,6,6,7,8,8,‐hexamethylcyclopenta‐γ‐2‐benzopyran (HHCB) and the insect repellent N,N ‐Diethyl‐ m ‐toluamide (DEET) to available monitoring data at comparable flow conditions. The iSTREEM low‐flow model results yielded a conservative distribution of values, whereas the mean‐flow model results more closely resembled the concentration distribution of monitoring data. We demonstrate how model results can be used to construct a conservative estimation of the distribution of chemical concentrations for effluents and streams leading to the derivation of a predicted environmental concentration (PEC) using the high end of the concentration distribution (e.g., 90th percentile). Data requirements, assumptions, and applications of iSTREEM are discussed in the context of other down‐the‐drain modeling approaches to enhance understanding of comparative advantages and uncertainties for prospective users interested in exposure modeling for ecological risk assessment. Integr Environ Assess Manag 2016;12:782–792. © 2016 SETAC