Effect of the Formulation of Vegetative Filter Strips Pesticide Residue Degradation on Environmental Exposure Assessments
Understanding and being able to simulate the fate and transport of pesticides from the application on a field, through a vegetative filter strip (VFS), and finally to adjacent receiving water bodies is critical for conducting high-tier environmental exposure risk assessments (ERA). Previous research has proposed a modeling framework that links the U.S. Environmental Protection Agency’s (US-EPA) PRZM/EXAMS with a well-tested process-based model for VFS (VFSMOD). This was recently updated to consider pesticide residue trapped in the VFS and degradation prior to subsequent rainfall/runoff events. However, there is disagreement among different ERA regulatory agencies on how different formulations incorporate modifications for temperature and soil water dynamics may affect pesticide loads and the final estimated environmental concentration (EECs) in the aquatic environment. The objective of this research was to update the current modeling approach to consider four formulations for VFS pesticide degradation to accommodate different regulatory environments, and to determine if residues in the VFS and/or aquatic EECs differed among formulations. The importance of the degradation formulations was evaluated for two model pesticides (mobile and rapidly degrading versus less mobile and persistent) for three distinct agroecological scenarios (continental row-crop agriculture, wet maritime extensive agriculture, and dry Mediterranean intensive horticulture) and for receiving water systems lacking VFS, and with VFS of lengths of 1 to 9 m. While the type of degradation equation was important in long-term assessments to predict VFS residues at the beginning of each storm event (statistically different at p<0.01), the degradation formulation was not found important relative to EECs estimation. These results are important since they indicate that the impact of considerations on pesticide residue degradation formulation on EECs estimated is negligible in what it refers to EECs modeled through a VFS. The approach can also inform the relative importance of field degradation processes.
Amy Ritter (Waterborne Environmental), Rafael Munoz-Carpena2, Garey Fox (North Carolina State University), Oscar Perez-Ovilla(Bayer CropScience), Ismael Rodea-Palomares (University of Florida). Effect of the Formulation of Vegetative Filter Strips Pesticide Residue Degradation on Environmental Exposure Assessments. Platform. ACS 2017. Washington DC.
Use of the OECD ENASGIPS Crosswalk Tool
One of the deliverables from the OECD Pesticide Dissipation Project is a GIS-based application to assess the similarity of ecoregions between Europe and North America. The objective of this tool is to find matching ecoregions which enable registrants to demonstrate that foreign test site conditions exist in either Europe or North America. This GIS application has the potential of being used in a variety of manners. Risk assessors can easily determine if e.g. the dissipation results from rice studies conducted in the US are applicable to European registration and vice versa. Although, the tool is easy to use, expert knowledge regarding the underlying data and model help with interpretation? the results. In this presentation, we will explore how the tool and the underlying data can be used to find locations with environmental conditions that match foreign test sites, and the implications of registration of pesticides in Europe from an ecoregion perspective. In addition, we will address issues such as crop data, discuss the implications of using long-term versus short term field data, and account for variability in climate and soil properties and the impact on site selection.
G.Hoogeweg, C.M. Holmes (Waterborne Environmental). Use of the OECD ENASGIPS Crosswalk Tool. SETAC Europe 2017. Poster.
PostersHome and Personal Care Products2017
A Framework for Dynamic Estimation of Aquatic Environmental Concentrations of Microplastics Via WWTP Discharge
Down-the-drain exposure models provide a valuable screening-level tool for estimating environmental exposure to substances which are treated and discharged at municipal wastewater treatment plants (WWTPs). Microplastics enter WWTPs from a variety of sources. As such, exposure models traditionally used for chemicals may also be utilized for particle emissions into the environment from WWTP discharge. These models often account for removal in WWTP as well as in-river decay processes. However, in light of incomplete and changing knowledge on microplastic fate in surface waters, we developed a framework in which microplastic use rates and general properties can be used to estimate the range of expected environmental concentrations depending on assumptions about removal and decay. We developed a web-based tool incorporating 10 removal rates and 10 decay rates encompassing the typical and extreme ranges of possible values. Each of the 100 model runs produces a distribution of Predicted Environmental Concentration (PECs) representing each effluent impacted stream as described by the iSTREEM® model which estimates spatially-explicit concentrations of chemicals in effluent and receiving waters across the US. Output visualization in the interactive tool includes a broad view of all possible combinations in a matrix format, and a detailed view of the full distribution of PECs for individual model runs. Within the matrix, each of the 100 individual cells correspond to a selected percentile of the PEC distribution (e.g., 95th percentile) for tha combination of removal and decay. We demonstrate the utility of this framework using WWTP influent loadings of polyethylene microbeads from liquid soaps and shower gels estimated using per-capita usage (Gouin et al 2011) and combine with individual facility population served and flow estimates using the iSTREEM model. We can the investigate the question … What kind of environmental concentrations might we estimate using these emissions? This dynamic framework can be used to help inform environmental exposure assessments by readily providing PECs based on varying model inputs on WWTP removal and in-stream decay rates for microplastics, which continues to evolve as more research is conducted. While this framework was applied to the US at a national scale, the framework itself is not geographic-dependent and could function equally well utilizing PEC distributions from Europe or elsewhere.
C.M. Holmes, R. Vamshi, N.Maples-Reynolds (Waterborne Environmental); I.A. Davies, B. Jonas (Personal Care Products Council), S.D. Dyer (The Procter & Gamble
Company / Environmental Stewardship and Sustainability Organization). A Framework for Dynamic Estimation of Aquatic Environmental Concentrations of Microplastics Via WWTP Discharge. SETAC EU 2017. Poster.
PresentationsHome and Personal Care Products2017
Integrating Treatment Facility and River Network Information to Model Spatially-Explicit Environmental Concentrations of Down-The-Drain Substances: ISTREEM
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
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.
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.