ISTREEM®: An approach for broad‐scale in‐stream exposure assessment of "down‐the‐drain" chemicals. (29th August 2016)

• Record Type: Journal Article
• Authors: Kapo, Katherine E; DeLeo, Paul C; Vamshi, Raghu; Holmes, Christopher M; Ferrer, Darci; Dyer, Scott D; Wang, Xinhao; White‐Hull, Charlotte
• Is Part Of: Integrated environmental assessment and management. Volume 12:Number 4(2016:Oct.)
• Page Start: 782
• Page End: 792
• Publication Date: 2016-08-29
• Subjects: Risk assessment -- Exposure model -- Geographic information systems -- Wastewater -- Effluent; Environmental management -- Periodicals; Pollution -- Periodicals; Environmental toxicology -- Periodicals; Environmental risk assessment -- Periodicals; Environmental impact analysis -- Periodicals; 628
• DOI: 10.1002/ieam.1793
• Languages: English
• ISSNs: 1551-3777

Abstract

ABSTRACT: 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 Key Points: The iSTREEM ® environmental exposure model predicts in‐stream concentrations of "down‐the‐drain" chemicals across broad geographic scales (national, regional) using spatial data for hydrology, wastewater treatment facilities, drinking water intakes, and associated information. The exposure scenarios generated by iSTREEM provide bounds for the typical mean flow‐based exposure and exposure based on extreme low flow (7Q10). A case study comparing model results to field monitoring data for HHCB and DEET at mean and low flow demonstrates the utility of the model as a screening‐level risk assessment tool. iSTREEM is freely available to the public as a Web‐based tool (www.istreem.org ), and the utility, features, and applications of the model continue to expand.