Comparison of Aquatic Exposure Assessment Models for Pesticide Use on Rice
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.
PostersHome and Personal Care Products2016
A Spatial Approach for Estimating the National Distribution of Sewer Residence Times for Wastewaters in the U.S.
Sewer residence time can have a significant influence on the environmental fate and transport of wastewater constituents, including down-the-drain household consumer product ingredients. In this study, best-available data resources and geoprocessing tools were used to develop a spatial approach for estimating the national distribution of sewer residence times for wastewaters in the U.S. Case studies estimating sewer residence times for two municipalities demonstrated that road networks could be used as a spatial proxy for sewer networks when the latter data is not available. The approach was then extrapolated to a national dataset of >3,400 wastewater treatment plant (WWTP) facilities across the U.S. to estimate the national distribution of sewer residence times, with an estimated national median sewer residence time of 3.3 hours. Sewer residence times for smaller WWTP facilities (< 1 million gallons per day) were comparatively shorter than larger facilities, however the latter comprised a greater proportion of the overall national wastewater volume. The sewer residence time distributions derived in this study can be combined with in-sewer biodegradation data to estimate WWTP influent concentrations of down-the-drain household consumer product ingredients as part of a national-scale probabilistic risk assessment.
Katherine Kapo, Raghu Vamshi, Megan Sebasky (Waterborne), Michael Paschka, Kathleen McDonough (P&G). “A Spatial Approach for Estimating the National Distribution of Sewer Residence Times for Wastewaters in the U.S.” Poster. SETAC NA 2016.
PresentationsHome and Personal Care Products2016
Spatial Improvements Leading to Advances in Down-the-Drain Chemical Exposure Modeling with iSTREEM® 2.0
iSTREEM® (“in-stream exposure model”) is a publicly-available web-based model (www.istreem.org) that estimates down-the-drain chemical concentrations in waste water treatment plant (WWTP) effluents, drinking water intakes (DWI), and in streams impacted by domestic waste water effluent across the continental U.S. and a number of watersheds in Canada under mean annual and low-flow (7Q10) conditions. Major upgrades to the model’s underlying data were made by incorporating higher-resolution and more current spatial datasets, leading to the release of iSTREEM® 2.0. The presentation provides an overview of the development of iSTREEM® 2.0, including how specific data needs were addressed and major assumptions considered in developing the model. The model river network was upgraded to a higher-resolution hydrologic dataset based on the USEPA and USGS NHDPlus version 2, which constitutes about 228,000 river segments totaling 243,000 river miles across continental U.S. For all the river segments, estimated mean annual flows were derived from NHDPlus, but low flows (7Q10) were exclusively developed for iSTREEM® 2.0. WWTP and associated facility level information were derived from the most recent USEPA Clean Watershed Needs Survey 2012 dataset, which includes about 13,000 facilities accounting for a total population of 175 million and effluent flow of 25,000 MGD. WWTP facilities were associated to the river network by applying techniques developed by USEPA. Enhancements to the model algorithm has made it possible to run the simulations efficiently and examine chemical exposure at a detailed spatial scale over a large geography (river basins or U.S.). Model simulation results are accessible to users in tabular (MS Excel) and spatial (MS Access) data formats for easy interpretation and further customization. A case study comparing prior version of the model and latest iSTREEM® 2.0 for the U.S will be presented to examine the impact of recent upgrades to model results – with focus on the national distribution of flows (mean and 7Q10’s), effluent PEC’s, water use, dilution factors, and receiving surface water PEC’s. The developments to iSTREEM® improves its utility as a tool to support environmental exposure assessments by a variety of users for environmental risk assessments across multiple commodity groups (personal care products, pharmaceuticals, food additives, pesticides, etc.).
Raghu Vamshi, Katherine Kapo, Chris Holmes (Waterborne), Paul DeLeo, Darci Ferrer (American Cleaning Institute). “Spatial Improvements Leading to Advances in Down-the-Drain Chemical Exposure Modeling with iSTREEM® 2.0“. Presentation. SETAC NA Orlando. 2016.
Endangered Species Risk Assessment Approaches for a Data-Rich Insecticide-Carbaryl
National-scale endangered species risk assessments for crop protection products continue to be challenging due to the large amount of data and uncertainties involved in these analyses. The variety of use patterns, volume of environmental fate and ecological effects data, overall diversity and number of federally listed species, and other factors can substantially add to the complex nature of these assessments. At the same time, this volume of information greatly enhances the assessor’s ability to increase the overall reliability and relevance of the risk assessment to listed species by allowing for more specific surrogacy assignments and exposure reflecting actual use patterns in potential proximity to species habitat areas. The insecticide carbaryl is an example of a well-studied crop protection product with decades of use experience and whose rich database allows for a pragmatic and detailed endangered species risk assessment. Like most products, biological sensitivity ranges are based on factors such as mode of action, receptor sites, metabolism etc. This information is crucial to understand differences in sensitivities between and within species taxa so that toxicity data can be better related to potential effects to specific listed species. Equally important is the thorough understanding of species habitats and locations so that exposure estimates can be accurately characterized. The full range of exposures and effects must then be uniquely related to use patterns, geographies and listed species for risk to be appropriately characterized to populations. In this paper, we will demonstrate examples of how this data can be collected, analyzed and applied to a national scale risk assessment for carbaryl. The pragmatic use of these best available data will allow for a more accurate and species focused risk estimate so that resources can appropriately be directed to stressors and listed species.
A Risk Assessment Process for Establishing Negligible Risk Earlier in National-Scale Endangered Species Assessments
The stepwise endangered species risk assessment process detailed in the Interim Approach combined with more recent approaches communicated by the Federal Agencies (hereafter referred to as “Agency Methods”) in the draft Organophosphate Biological Opinions has yielded useful insights regarding the utility and practical limitations of these methods for risk assessment screening purposes. Agency Methods, while conservative by design, do not clearly incorporate opportunities to take advantage of readily-available information and simple strategies that can optimize the screening ability of the process while maintaining adequate conservatism desired for listed species protection. When strictly following Agency Methods, the number of listed species and habitats where risk is presumed, and therefore require a jeopardy evaluation, is excessive but the level of species relevance and best use of data lacking. As a result, the effectiveness of a tiered assessment process is greatly reduced. Further, the boundary between approaches and refinements used in Step 1 (“May Affect/No Effect”) and Step 2 (“Likely/Not Likely to Adversely Affect) can become unclear and even irrelevant due to the iterative nature of risk assessment. Regardless of the formal step outlined, there is a practical continuum of refinements and approaches that can be applied to effects and exposure analyses to establish negligible risk earlier in the risk assessment. The framework and decision criteria used within the framework should not be such that “Likely to Adversely Affect” decisions are commonly reached due to arbitrary limitations without fully utilizing available species habitat and biological data, species relevant exposure estimates, and surrogate ecotoxicity data. To that end, a systematic process for efficiently and effectively determining negligible risk for species and their habitats early in an assessment is presented. The approach is based on a set of fundamental “best-practices” developed from experience in conducting listed species assessments.
Matthew Kern, Nathan Snyder, Joshua Amos, Katherine Kapo (Waterborne Environmental). “A Risk Assessment Process for Establishing Negligible Risk Earlier in National-Scale Endangered Species Assessments“. Presentation. SETAC NA 2016.
A Risk Assessment Process for Establishing Negligible Risk Earlier in National-Scale Endangered Species Assessments
Matt Kern, Katherine Kapo, Nathan Snyder, Josh Amos, Megan Sebasky, Dan Perkins, Gregg Hancock and Amelie Schmolke (Waterborne Environmental). “A Risk Assessment Process for Establishing Negligible Risk Earlier in National-Scale Endangered Species Assessments”. Presentation. CLA RISE. April 2016.
PostersAgriculture and Food2016
Modeling Watershed-Scale Cover Crop Impact on Nitrate Availability and Transport
Presented at the 2016 Hypoxia Task Force Meeting in St. Louis, MO.
Daniel Perkins, PhD., Rohith Gali, PhD. (Waterborne) and Caroline Wade (Illinois Corn Growers Association).”Modeling Watershed-Scale Cover Crop Impact on Nitrate Availability and Transport“.Poster. Hypoxia Task Force Spring 2016.
Refined Aquatic Exposure Estimates based on Species Data from the Pilot Biological Evaluations
The draft biological evaluations (BEs) released by USEPA assessing three pilot chemicals utilized a regionalized assessment methodology for assessing exposure to endangered species living in aquatic environments. Aquatic exposure was assessed using several fixed receiving water (habitat) dimensions, referred to as aquatic bins. The BEs also included a detailed summary of USFWS information regarding habitat waterbodies and species locations. In this presentation, a tiered exposure assessment methodology is proposed that builds off of the scenario based exposure methodologies, but also extends beyond and utilizes species relevant data as early in the process as feasible. Refinements addressing habitat hydrodynamics with appropriate modeling approaches will be presented as refinements using readily available modeling tools and conservative assumptions. In the presentation of results, USEPA clearly identified extreme exposure predictions and expressed desire for ideas on refinements. This presentation seeks to answer that call in a species relevant and specific manner that allows for scaling to the appropriate chemical use footprint with focus on species habitat area. Results allow for use in screening level deterministic risk assessments. They can be further integrated with surrogate species dose response curves or sensitivity distributions for a species focused probabilistic risk expression. Temporal analysis could also be derived from the results. Implementing a species focused analysis framework using actual habitat data to inform model refinements also provides the opportunity to incorporate mitigating factors in the exposure assessment. Model tools should incorporate naturally occurring landscape mitigating factors (i.e. landscape based treatment buffers from listed stream habitats, percent crop area) as well as label or management based mitigation measures (i.e. drift buffers or protected lands). The goal of a national assessment should be to generate relevant exposure estimates by including best available data in a pragmatic way.
Nathan Snyder, Raghu Vamshi, Josh Amos, Amy Ritter, Daniel Perkins, Ph.D., Kendall Jones, Rohith Gali, Ph.D. (Waterborne). “Refined Aquatic Exposure Estimates based on Species Data from the Pilot Biological Evaluations“. Poster. SETAC NA 2016.
Three Estuarine Mixing Scenarios for Pesticide Risk Assessment
Session: Environmental Fate, Transport & Modeling of Agriculturally-Related Chemicals
Time: 1:30PM – 1:55PM
Location: Regency Ballroom C1 – Loews Philadelphia Hotel
The US EPA, the National Marine Fisheries Service, the US Fish & Wildlife Service, and pesticide registrants are focused on accurately assessing the potential risks of pesticides to threatened and endangered species. Currently, the EPA’s Office of Pesticide Programs assesses risk with a modeling system, the Pesticide in Water Calculator (PWC), which couples the daily-time-step, field-scale numerical-solution model Pesticide Root Zone Model (PRZM) with the Variable Volume Water Model (VVWM). The VVWM has various receiving water mixing scenarios, including estuarine and coastal zones, but none of the scenarios consider tidally-driven sea water stratification and sediment transport processes. This creates a significant gap in understanding the exposure component of pesticide risk assessment, since the toxicology data component – – pesticide toxicity to marine and estuarine organisms – – is usually complete and available. We propose to create three distinct marine/estuarine mixing scenarios for incorporation into the VVWM: salmonids in the Pacific Northwest, coral in the Hawaiian Islands or the Florida Keys, and crustaceans in the Chesapeake Bay. The diverse scenarios include a coastal embayment or a marine shoreline, a salt wedge estuary, and a drowned eroded river valley. The biology of target species will drive the development of each scenario; e.g., the coral reef embayments will not have high TSS concentrations (coral doesn’t grow in high TSS environments). A key consideration will be the exchange coefficient, i.e., the exchange of conservative substances due to tidal circulation. The full semi-diurnal tide will be considered so that times such as the slack tide period, when many of the organisms are feeding and there is low mixing, will be fully considered. The study will characterize the circulation, geometry, and aquatic chemistry of each habitat. Water, salt, and pesticide mass balances based on box model volume elements will be constructed that represent multiple vertical and horizontal segments. A key phase will be testing the models against field data for each scenario.
Stuart Cohen (Environmental & Turf Services), Louis Thibodeaux (Louisiana State University), Craig Jones (Integral Consulting), Martin Williams (Waterborne Environmental), Sandra Haefner (Environmental & Turf Services). “Three Estuarine Mixing Scenarios for Pesticide Risk Assessment”. ACS Philadelphia Presentation. August 2016.
Approaches for Mapping the Habitat of Listed Species without Federally Declared Critical Habitat
Spatially explicit sub-county habitat for federally listed species based on defensible scientific approaches allows for greater confidence and more realism in assessing the potential risk that pesticides have to listed species. Currently, refined spatial habitat information for a large number of listed species remains unresolved. Of the nearly 1,680 listed species in the US, approximately 788 have federally declared Critical Habitat suitable for use in national scale regulatory assessments. In the draft Biological Evaluations for three organophosphate compounds published in the spring of 2016, USEPA incorporated species range maps provided by The Services to make effects determinations for nearly all listed species; however, these range maps are not yet publicly available.
This poster presents a study to explore approaches for efficiently generating spatial habitat using current data sources and techniques. While the habitat generated cannot represent “Critical Habitat”, it should represent the physical and biological features occupied by the species. The goal is spatial data of appropriate accuracy and resolution for use with potential pesticide use sites in national-scale pesticide risk assessments. The science applied must be transparent and instill confidence in stakeholders that the data are representative and protective of the listed species.
Federal Registry, USFWS reports, and NatureServe species profiles are highlighted as sources of textual habitat descriptions to inform both suitable habitat delineation and subsequent refinements to represent the often localized distributions of many endangered species. Tiered habitat maps are presented that show a tapering view from range to the biophysical habitat parameters selected to represent suitable habitat. Several terrestrial, plant, and/or aquatic species across taxonomic groups are showcased.
Josh Amos, Megan Sebasky*, Brian Kearns (Waterborne Environmental), Steve Kay (Pyxis).”Approaches for Mapping the Habitat of Listed Species without Federally Declared Critical Habitat“. Poster. SETAC NA. 2016.