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Publications: 2017

PresentationsHome and Personal Care Products2017

Integrating Treatment Facility and River Network Information to Model Spatially-Explicit Environmental Concentrations of Down-The-Drain Substances: ISTREEM

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iSTREEM® is a web-based model which estimates spatially-explicit environmental concentrations of down-the-drain chemicals in effluent and receiving waters across the USA. Concentrations are estimated at the discharge points of over 10,000 municipal wastewater treatment plants (WWTPs) and downstream receiving waters covering more than 350,000 km of rivers. The model incorporates WWTP information on population served, treatment type, and facility flow which are linked to a commonly used hydrology framework providing flow and hydrologic connectivity between facilities and downstream sites. As part of the hydrologic routing, a first-order decay is implemented to simulate environmental processes that remove chemical from the water column. The model allows for regional use rates to better simulate potential geographic variability in emissions, as well as differing removal rates to account for different facility treatment types. Given the assumption of temporally constant emission, the model is able to efficiently execute as a single, annual model run. The publicly available web-based model (www.iStreem.org) exemplifies open access to modeling resources, with no software installation required, and computation resources for model runs performed by the iSTREEM server. Users are able to save and retrieve runs, interact with results in a map format, or download source data and model results for more in-depth analysis by the user, including linking to desktop mapping software. The model, sponsored by the American Cleaning Institute (ACI, www.cleaninginstitute.org), is a valuable tool for both promoting product and ingredient stewardship and potential regulatory compliance for chemical suppliers and manufacturers of formulated products. The framework and modular nature of the model allow it to be applied to different geographies beyond the current USA-wide dataset.

C.M. Holmes, R. Vamshi (Waterborne Environmental); P. DeLeo, D. Ferrer (American Cleaning Institute); S.D. Dyer (The Procter & Gamble Company / Environmental Stewardship and Sustainability Organization). Integrating Treatment Facility and River Network Information to Model Spatially-Explicit Environmental Concentrations of Down-The-Drain Substances: ISTREEM. Presentation. SETAC Europe 2017.

PresentationsHome and Personal Care Products2017

Estimating Sewer Residence Time at the National Scale to Enable Probabilistic Risk Assessment of Down-The-Drain Household Consumer Product Ingredients

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Many household consumer product ingredients disposed of down-the-drain can undergo significant degradation in the sewer system prior to being treated and discharged from a wastewater treatment facility. Understanding the distribution of sewer residence times for wastewater at the national scale, in combination with in-sewer biodegradation data for specific chemicals, can provide a more realistic assessment of environmental exposure and risk. However, the availability of data for sewer residence times at the national or regional scale is currently limited. We overview how commonly-available data resources such as road networks, land use and population data, and wastewater treatment facility data can be analyzed spatially to estimate the distribution of sewer residence times at a national or regional scale. This approach was developed using case study sewer system data and extrapolated to a national dataset of over 3,400 wastewater treatment facilities across the U.S., yielding a national median residence time of 3.3 hours. We demonstrate how sewer residence time distributions derived by this spatial approach can be used as a tool to enable probabilistic risk assessment of down-the-drain household consumer product ingredients for a given country or region.

K.E. Kapo, R. Vamshi, M. Sebasky, C.M. Holmes (Waterborne Environmental), M. Paschka, K. McDonough (P&G). “Estimating Sewer Residence Time at the National Scale to Enable Probabilistic Risk Assessment of Down-The-Drain Household Consumer Product Ingredients”. Presentation. SETAC EU 2017.

PresentationsCrop Protection2017

Comparison of Aquatic Exposure Assessment Models for Pesticide Use on Rice

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An evaluation of six modeling approaches for predicting environmental concentrations associated with the use of crop protection chemicals on rice was conducted. A comparison of predicted environmental concentrations (PECs) computed with all six approaches (EPA Tier 1, MED-RICE, Japanese regulatory spreadsheet “Aquatic PEC”, SWAGW, RICEWQ-EXAMS, and PFAM) is presented along with the status of their regulatory acceptance for pesticide registration in the United States, European Union, China, and Japan. RICEWQ-EXAMS is used in the Pesticide Risk Assessment Exposure Simulation Shell (PRAESS) for China Scenarios and for higher tier in Europe. Of the six models, RICEWQ and PFAM models have the capability to simulate multiple pesticide applications,metabolites, and the flooding, overflow, and controlled releases of water associated with rice production. Each country has different guidance on which model, input parameters and ecological environments are used for computing PECs. A description of each model/scenario will be presented a long with a comparison of PECs from two pesticides using each model.

A. Ritter, M. Cheplick, G. Hoogeweg, C.M. Holmes (Waterborne Environmental). Comparison of aquatic exposure assessment models for pesticide use on rice. SETAC BRUSSELS. Presentation. April 2017.