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PresentationsCrop Protection2016

Leveraging Ambient and Focused Monitoring Data to Refine Regulatory Modeling Exposure Estimates

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  • Session title: Increasing the Value of Water Monitoring Data for Pesticide Fate & Effects Evaluations
  • Presentation type: Presentation
  • Presentation room: Commonwealth Hall A1 at 9:20-9:45AM
  • Presenting Author: Nathan Snyder

Re-registration of crop protection products under USEPA or Health Canada’s PMRA regulatory frameworks lead to a revision of exposure estimates based on updating of regulatory tools and guidance for use of environmental fate data. Particularly with revised groundwater tools, risks are being identified that are substantially different than previous assessments or as demonstrated in the monitoring data. For products with a long use history, extensive monitoring data is often available. In this case study, the authors will present a comparison of the extensive monitoring data and new exposure estimates. Learnings from detailed studies like Prospective Groundwater (PGW) Studies along with the use of monitoring data points with demonstrated applicability to labeled use patterns are used to improve the modeling predictions by presenting scenarios and parameterization refinement options. The authors will highlight areas where monitoring can be used to augment the modeling efforts leading to protective, yet more realistic exposure estimates for use in risk assessments.

Nathan Snyder*, Kendall Jones (Waterborne Environmental), Aldos Barefoot (DuPont). “Leveraging Ambient and Focused Monitoring Data to Refine Regulatory Modeling Exposure Estimates”. Presentation. ACS 2016.

Papers & ReportsAgriculture and Food, Crop Protection2016

Investigating Past Range Dynamics for a Weed of Cultivation, Silene vulgaris

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Since the last glacial maximum (LGM), many plant and animal taxa have expanded their ranges by migration from glacial refugia. Weeds of cultivation may have followed this trend or spread globally following the expansion of agriculture or ruderal habitats associated with human-mediated disturbance. We tested whether the range expansion of the weed Silene vulgaris across Europe fit the classical model of postglacial expansion from southern refugia, or followed known routes of the expansion of human agricultural practices. We used species distribution modeling to predict spatial patterns of postglacial expansion and contrasted these with the patterns of human agricultural expansion. A population genetic analysis using microsatellite loci was then used to test which scenario was better supported by spatial patterns of genetic diversity and structure. Genetic diversity was highest in southern Europe and declined with increasing latitude. Locations of ancestral demes from genetic cluster analysis were consistent with areas of predicted refugia. Species distribution models showed the most suitable habitat in the LGM on the southern coasts of Europe. These results support the typical postglacial northward colonization from southern refugia while refuting the east-to-west agricultural spread as the main mode of expansion for S. vulgaris. We know that S. vulgaris has recently colonized many regions (including North America and other continents) through human-mediated dispersal, but there is no evidence for a direct link between the Neolithic expansion of agriculture and current patterns of genetic diversity of S. vulgaris in Europe. Therefore, the history of range expansion of S. vulgaris likely began with postglacial expansion after the LGM, followed by more recent global dispersal by humans.

Sebasky, M. E., Keller, S. R. and Taylor, D. R. (2016), Investigating past range dynamics for a weed of cultivation, Silene vulgaris. Ecol Evol. doi:10.1002/ece3.2250

PresentationsVeterinary Medicines2016

Refined exposure estimation to support an Environmental Assessment for a veterinary medicine

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  • Session title: Science based strategies for the environmental assessment and management of pharmaceuticals and veterinary medicines
  • Presentation type: Platform
  • Presentation room: Salle R0-B at 11:30AM
  • Presenter: Chris Holmes

The U.S. Food and Drug Administration, Center for Veterinary Medicine, evaluates whether significant environmental impacts would occur with the approval of new animal drugs pursuant to the National Environmental Policy Act. The approval process may require the preparation of an environmental assessment (EA), which contains sections addressing problem formulation, environmental fate, exposure, effects and risk characterization. Using a recent EA as a framework, this presentation will focus on the refinement of environmental exposure estimates using spatial techniques to identify representative and protective environmental scenarios, and link them to exposure models commonly used in the U.S. Environmental Protection Agency (USEPA) pesticide registration process. A Geographic Information System (GIS) was used to identify regions of high exposure potential across the US based on beef cattle characteristics and climatic conditions. From within each region, a single vulnerable watershed was selected and characterized for watershed-scale modelling following USEPA Tier-2 pesticide exposure approaches. Three potential sources of chemical were modelled: feedlots, agricultural fields applied with manure collected from the feedlots, and pasture. Using PRZM and EXAMS models, runoff and erosion inputs to surface water from these sources were assessed over a 30-year timeframe to produce final PECs suitable for use in the effects portion of the EA. The results of the national vulnerability assessment identified five regions with diverse intensive-use characteristics. From within these, a single intense-use watershed was selected and modelled. Loadings from each of the land covers were combined on a daily basis and transported to the receiving water body, from which daily PECs were calculated. Based on the aggregate aquatic exposure, no significant effects were identified and a Finding of No Significant Impact (FONSI) was determined. The process presented here discusses the development of refined methods to estimate exposure using spatial techniques to identify representative and protective environmental scenarios. It linked these scenarios to accepted EPA exposure models which addressed all potential sources of chemical loading and produced a series of surface water PECs suitable for risk characterization. This approach is a robust and viable methodology incorporating real world information but maintains inherent safety assumptions from USEPA Tier-2 pesticide framework.

 

Chris Holmes, Isha Khanijo, Josh Amos, Amy Ritter (Waterborne Environmental), Holly Zahner (CVM), Eric Silberhorn (CVM), Dawn Merritt (Zoetis). “Refined exposure estimation to support an Environmental Assessment for a veterinary medicine”. Platform. SETAC EU 2016.

PostersHome and Personal Care Products2016

iSTREEM 2.0: new enhancements for down-the-drain modeling to support environmental aquatic exposure assessments for cosmetics and personal care products

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  • Session title: Challenges in Environmental Assessment of Cosmetics and Personal Care Products
  • Presentation type: Poster
  • Presentation room: Exhibition Hall opens at 8:10AM
  • Presenting Author: Chris Holmes

The iSTREEM® model (“in-stream exposure model”), a free and publically-available web-based model supported by the American Cleaning Institute (istreem.org), provides a means to estimate chemical concentrations in effluent, receiving waters, and drinking water intakes (DWI) across the conterminous U.S. as well a number of watersheds in Canada under mean annual and low-flow (7Q10) conditions. This presentation will discuss recent upgrades made to enhance the model, underlying data, algorithms and presentation of results in the new version. iSTREEM® 2.0 incorporates geographic locations of over 12,000 wastewater treatment plant (WWTP) facilities along more than 300,000 segments of effluent-impacted river reaches, providing a framework to integrate geographic data to assess environmental risk for multiple scenarios of interest. WWTP facilities and associated facility level information were derived from the latest available USEPA Clean Watershed Needs Surveys. The river network used by iSTREEM® 2.0 was upgraded to a higher-resolution hydrologic dataset based on the USGS/USEPA NHDPlus version 2, which includes estimated mean annual and low flow (7Q10) data based on USGS stream gage measurements. Model results are presented in a standardized manner for consistent results communication across all users and are provided in a readily usable format (MS Excel) for easy interpretation and further customization of result presentation. Major assumptions used in constructing the model will be discussed. Recent developments are geared to expand adoption of the model by a wide variety of users as an environmental risk assessment tool across multiple commodity groups (cosmetics, personal care products, pharmaceuticals, food additives, pesticides, etc.) that require internal or regulatory environmental assessments. The discussion will also include a comparison of model results between the prior version of iSTREEM® and latest iSTREEM® 2.0 to examine the impact of recent upgrades on the national distribution of predicted environmental concentrations.

Raghu Vamshi, Katherine Kapo, Megan Sebasky, Chris Holmes (Waterborne Environmental); Paul DeLeo, Darci Ferrer (American Cleaning Institute). “2.0: new enhancements for down-the-drain modeling to support environmental aquatic exposure assessments for cosmetics and personal care products”. Poster. SETAC EU 2016.

PostersCrop Protection2016

Prospective risk assessment for mixtures of agricultural chemicals in surface water

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  • Session title: Environmental risk assessment of chemical mixtures: the steps ahead
  • Presentation type: Poster
  • Presentation room: Exhibition Hall opens at 8:10AM
  • Presenting Author: Chris Holmes

In March of 2015, a SETAC Pellston workshop was held to help inform decision making around aquatic mixture risk assessments of chemicals using exposure scenarios and decision trees. The efforts were broadly grouped into three areas of chemical origination: agriculture, domestic, and urban influences (a separate integration group was charged with looking at overarching issues). The agricultural land use combined effect measures with exposure scenarios of chemical mixtures for field and catchmentscale using procedures that are recognized and used in regulatory schemes in the U.S., Europe and other parts of the world. Chemicals modeled were those used in crop protection and livestock production, and were considered to occur as mixtures (in time and space). Two types of scenarios were defined including a single unit that could represent a variety of typical chemical input locations (e.g., feed lot, agricultural field, pasture, aquaculture, biosolids applications, etc). The second scenario was multi-unit, combining several different uses within a single catchment/watershed. These assessments considered inputs from spray drift, surface runoff and erosion, and/or tile drainage systems on a daily basis over an extended period of time (e.g., from one to 30 years). Case studies included a single unit scenario modeled as a wheat field in Eastern UK, consisting of crop protection applications of 13 substances over the course of the year. This scenario used standard FOCUS soil, weather and receiving water body information for consistency. The case study of a multi-unit catchment scenario consisted of a combination of corn fields, pasture, and feedlot inputs based in part on the US EPA Iowa corn scenario used in pesticide registration evaluations. Manure from treated cattle containing two different pharmaceutical substances (a parasiticide and a macrolide antibiotic) was applied to corn fields as fertilizer, and also originated from pastured cattle. Twelve different active substances for crop protection were modeled on the corn field. These applications ranged from a pre-plant herbicide to a late-year fungicide application. A risk assessment decision tree looked at estimated environmental concentrations of all active substances on a daily basis, with subsequent mixture risks evaluated according to methodologies developed under a separate effects workgroup within the same Pellston workshop. A summary of the framework, methodologies and results will be presented.

Chris Holmes (Waterborne Environmental),  M. Hamer (Syngenta), C. Brown (University of York), Russell Jones (Bayer CropScience); L. Maltby (The University of Sheffield); Eric Silberhorn (US Food & Drug Administration); J. Teeter (Elanco Animal Health), M.S. Warne (DSITI), L. Weltje (BASF SE). “Prospective risk assessment for mixtures of agricultural chemicals in surface water”. Poster. SETAC EU 2016.

PostersWater/Wastewater Assessments2016

Environmental exposure assessment of sucralose in receiving waters at differing spatial scales

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  • Session title: Advances in exposure modelling: bridging the gap between research and application
  • Presentation type: Poster
  • Presentation room: Exhibition Hall opens at 8:10AM
  • Presenting Author: Chris Holmes

Down-the-drain exposure models provide a valuable screening-level tool for estimating environmental exposure to product ingredients which are treated and discharged at municipal wastewater treatment plants. We present an environmental exposure assessment for sucralose, an artificial sweetener which ultimately ends up in the environment via down the drain emissions. Exposure modeling was performed using the iSTREEM® model, a publically-available web-based model supported by the American Cleaning Institute (www.istreem.org) which estimates spatially-explicit concentrations of chemicals in effluent and receiving waters across the U.S. at mean and low flow conditions. Wastewater treatment facility influent loadings of sucralose were estimated using per-capita usage derived from market sales volume combined with individual facility population served and daily flow estimates within the iSTREEM® model. The screening-level assessment used an assumption of zero removal during treatment and no in-stream decay, resulting in a representation of “worst-case” environmental exposure estimates. Three case studies of modeling at different spatial extents are presented: national scale of the continental U.S., regional scale of the Lake Erie drainage basin, and local scale of the Grand River Watershed in Canada. US-wide predicted environmental concentrations (PECs) estimated by the model at mean annual flow conditions were comparable to sucralose concentrations typically expected to be observed in the field, with a 90th percentile PEC in surface waters of approximately 1.9 µg/L. Watershedscale modeling of the Grand River was compared to published data from 23 sites measured in 2007-2009. This local assessment was enhanced with temporally-specific adjustments to flow. Once time-specific gaging data were added, the model predicted a comparable exposure pattern to those measured across the 23 sites. Maps of the estimated geographic distribution of US-wide and Grand River watershed river concentrations are presented using geo-referenced concentration data generated by the iSTREEM® model. These screening-level environmental exposure assessments provide an estimated distribution of PECs in a spatial and potentially temporal context. These can be used to inform risk management and/or subsequent higher-tier assessment.

Katherine Kapo, Raghu Vamshi, Megan Sebasky, Duane Huggett, Chris Holmes (Waterborne Environmental). “Environmental exposure assessment of sucralose in receiving waters at differing spatial scales”. Poster. SETAC EU 2016.

PostersCrop Protection2016

Does the inclusion of mass balance and degradation processes to vegetative filter strips impact long-term pesticide environmental exposure assessments?

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  • Session title: Advances in exposure modelling: bridging the gap between research and application
  • Presentation type: Poster
  • Presentation room: Exhibition Hall opens at 8:10AM
  • Presenting Author: Amy Ritter

Vegetative filter strips (VFS) are a widely adopted for reducing pesticide transport from adjacent fields to receiving water bodies. The long-term VFS efficacy is dependent on site-specific factors related to soils, weather, land use, vegetation and maintenance. The previous version of the well-tested process-based model for VFS (VFSMOD), assumed that pesticide mass stored in the VFS was not available for transport in subsequent storm events. This research study uses an updated PRZM/VFSMOD/EXAMS modeling framework, by considering the effect of the addition of surface mass balance and four options of degradation processes on acute (peak) and chronic (60-d) aquatic environmental exposure concentrations (EECs) and percent reductions across three distinct 30-yr US EPA scenarios. Global sensitivity analysis (GSA) was used to assess the relative importance of adding or removing mass balance and degradation processes in the context of other important input factors like VFS length (VL), pesticide organic-carbon sorption coefficient (Koc), and half-lives in both water and soil phases. It was concluded that considering degradation in the VFS was not relatively important if single, large events were controlling the transport process, as is typical for the higher percentiles considered in standard exposure assessments. Degradation processes become more important when considering percent reductions in acute or chronic EECs, especially under scenarios with lower pesticide losses.

Amy Ritter (Waterborne Environmental), R. Muñoz-Carpena (University of Florida/Department of Hydrology Water Quality Agricultural Biological Engineering Faculty), Gary Fox (Oklahoma State University/Biosystems and Agricultural Engineering), Oscar Perez-Ovilla (Bayer CropScience). “Does the inclusion of mass balance and degradation processes to vegetative filter strips impact long-term pesticide environmental exposure assessments?”. Poster. SETAC EU 2016.

PostersCrop Protection2016

World Exposure Assessment Tools and Scenarios

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  • Session title: Modelling of pesticides and biocides fate and exposure in a regulatory context (P)
  • Presentation type: Poster
  • Presentation room: Exhibition hall opens at 8:10AM
  • Presenting Author: Amy Ritter

Modeling platforms have been developed to evaluate the potential impact of crop protection chemicals on the environment throughout the world. The tools currently have been configured with scenarios containing crop, soil, and weather conditions for major agricultural areas in Brazil, Canada, Colombia, the European Union, Norway, the People’s Republic of China, and the United States. Additionally, agricultural scenarios have been developed for countries such as Peru, Ecuador, Taiwan, Philippines, and Korea. All these scenarios are simulated using fate and transport models that have been accepted for regulatory assessment in the U.S. and the European Union, including the Pesticide Root Zone Model (PRZM), Exposure Analysis Modeling System (EXAMS), Rice Water Quality Model (RICEWQ), and Toxic Substances in Surface Waters (TOXWA). Development of country specific scenarios and tools will be described. A key strength of the tools are that scenarios can be added for additional geographical areas with relative ease and the appropriate regulatory endpoints.

A. Rittter, M. Cheplick, Waterborne Environment; G. Hoogeweg, C.M. Holmes, Waterborne Environmental. “World Exposure Assessment Tools and Scenarios”. Poster. SETAC EU 2016.

Papers & ReportsCrop Protection2015

Effects of formulation on transport of pyrethroids in residential settings

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Washoff of 17 pyrethroid products resulting from a 1-h, 25.4-mm rainfall occurring 24 h after application was measured in indoor studies with concrete slabs. These products included different pyrethroid active ingredients and a range of formulation types. Based on this replicated study, 5 product pairs with contrasting washoff behaviors were chosen for an outdoor study using 6 full-scale house fronts in central California. Products in 4 of these pairs were applied once to different rectangular areas on the driveway (1 product in each pair to 3 house lots and the other to the remaining 3 house lots). The products in the fifth pair were applied 3 times at 2-mo intervals to vertical stucco walls above the driveway. All house lots received natural and simulated rainfall over 7 mo. Indoor studies showed differences up to 170-fold between paired products, whereas the maximum difference between paired products in the field was only 5-fold. In the pair applied to the wall, 1 product had 91 times the washoff of the other in the indoor study, whereas in the field the same product had 15% lower washoff. These results show that, although the formulation may influence washoff under actual use conditions, its influence is complex and not always as predicted by indoor experiments. Because the formulation also affects insect control, washoff research needs to be conducted together with efficacy testing. Environ Toxicol Chem 2016;35:340–347. © 2015 The Authors. Published by Wiley Periodicals, Inc. on behalf of SETAC.

Jones, R. L., Trask, J. R., Hendley, P., Cox, M. J., Chepega, J. C., Harbourt, C. M. and Davidson, P. C. (2016), Effects of formulation on transport of pyrethroids in residential settings. Environ Toxicol Chem, 35: 340–347. doi:10.1002/etc.3188

Papers & ReportsCrop Protection2015

Hydrologic and Water Quality Modeling: Spatial and Temporal Considerations

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Hydrologic and water quality models are used to help manage water resources by investigating the effects of climate, land use, land management, and water management on water resources. Water-related issues are investigated over a range of scales, i.e., the extent and resolution of the spatial and temporal contexts, which can vary spatially from point to watershed and temporally from seconds to centuries. In addition, models’ formulations may place scale restrictions on their use. In 2012, ASABE published a collection of 22 articles on the calibration, validation, and use of 25 hydrologic and water quality models. Each article detailed the process to follow and the issues that could arise during calibration or application of a specific model. The objective of this article is to synthesize those articles with regard to common spatial and temporal scale principles that should guide selecting, parameterizing, and calibrating a hydrologic model. This article describes how the spatio-temporal extent and resolution of a model application should relate to the modeling objectives, the processes simulated, the parameterization and calibration process, data available for parameterization and calibration, and interpretation of results. Overall, the intended scale of the model should match the scale of the processes that need to be simulated given the modeling objectives, the scale of input and calibration data should be compatible with the scale of the model and with the objectives of the study, and the model should be calibrated at the scale at which the results will be analyzed and interpreted.

Baffaut, C.,  S.M. Dabney, M. Smolen, M.A. Youssef, J.V. Bonta, M.L. Chu, J.A. Guzman, V. Shedekar, M. K. Jha, and J.G. Arnold. Hydrologic and water quality modeling: spatial and temporal considerations. T. ASABE 58(6): 1661-1680