iSTREEM^®: An approach for broad-scale in-stream exposure assessment of “down-the-drain” chemicals

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.

Validation of AIST‐SHANEL Model Based on Spatiotemporally Extensive Monitoring Data of Linear Alkylbenzene Sulfonate in Japan: Toward a Better Strategy on Deriving Predicted Environmental Concentrations

“…No published investigations exist of environmental exposure model validations based on more than 10 000 data points of measured chemical concentrations in river water. Existing investigations of the validity of estimated concentrations in rivers in the United States, Europe, and Japan, calculated using exposure assessment models such as the in‐stream exposure model (iSTREEM), GREAT‐ER, G‐CIEMS, and AIST‐SHANEL, have been published; however, most of these studies used fewer than 500 data points (Suzuki et al ; Ishikawa and Tokai ; Kehrein et al ; Kapo et al ; Nishioka et al ). Thus, to our knowledge, in terms of the number of data points across an area, our research represents the most comprehensive comparison of measured and estimated values.…”

A Review of the Environmental Fate and Effects of Acesulfame‐Potassium

“…The iSTREEM model was acquired by the American Cleaning Institute (ACI, formerly the Soap and Detergent Association) in 2008. The ACI makes the modeling system freely available to the public, and they have sponsored further development and updating (Kapo et al 2016). Version 2.2 incorporates the most current information available on wastewater treatment facilities, and updates to the national river network to allow development of the most up‐to‐date national‐scale surface‐water exposure estimates.…”

A transformational approach to improve interpretation of environmental data

“…The article appearing in Integrated Environmental Assessment and Management (IEAM) by Kapo et al (this issue), titled “iSTREEM ® : An Approach for Broad‐Scale In‐Stream Exposure Assessment of Down the Drain Chemicals,” compared national distributions of chemical concentrations, modeled using chemical‐specific inputs for loading (per capita use) and treatment removal efficiency, as well as available data for wastewater treatment plant characteristics, drinking water intakes, and stream hydrology, to distributions of concentrations obtained from regional chemical monitoring programs across the United States. Two chemicals—a polycyclic musk fragrance ingredient used in a wide range of consumer products (1,3,4,6,7,8‐hexahydro‐4,6,6,7,8,8‐hexamethylcyclopenta–2‐benzopyran [HHCB]) and the most common active ingredient in insect repellent commercial products ( N , N ‐diethyl‐meta‐toluamide [DEET])—have been detected at low concentrations in water bodies throughout the United States as a result of widespread production and use.…”