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PresentationsCrop Protection2016

Placing EPA Tier II Scenarios into National Context in Terms of Runoff-Erosion Vulnerability After Pyrethroid Applications to Agriculture

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  • Session title: Environmental Fate, Transport & Modeling of Agriculturally-Related Chemicals
  • Presentation type: Presentation
  • Presentation room: Regency Ballroom C1 at 8:55AM
  • Presentation date: Wednesday, August 24, 2016
  • Presenting Author: Chris Holmes

US EPA regulatory evaluations of pesticides utilize crop-specific scenarios in a tiered exposure assessment framework. EPA defines the standard scenarios as “… best professional judgement sites expected to produce runoff greater than would be expected at 90% of the sites for a given crop/use”. In order to evaluate standard scenario relevance for pyrethroid runoff and erosion, PWG has examined 15 crop scenarios using two different approaches. Firstly, the single field scale where 10-ha of a single soil is 100% cropped to the crop of interest was considered. The 90thpercentile annual maximum runoff/erosion flux of a representative pyrethroid was estimated for each SSURGO soil shown by NASS CDL to have been cropped to each of the 15 crops over a 5-year period. This estimation used standard PRZM modeling with the nearest approved SAMSON 30-yr weather data and regional cropping dates. The second approach considered the real world catchment scale where surface waters receive runoff from multiple fields. The 90th percentile pyrethroid runoff/erosion fluxes were summed for all soil areas in each NHD+ catchment on which a given crop was grown. In both cases, the predicted runoff/erosion pyrethroid loads were ranked to produce distributions against which the runoff/erosion loads from the corresponding standard EPA Tier II scenarios were compared to assess their relative vulnerability. The first approach indicated that across the 15 EPA standard scenarios, predicted runoff/erosion loading vulnerabilities varied with approximately half above and half below the 85th percentile. However, when compared to the summed pyrethroid runoff/erosion fluxes from soils growing each crop in real-world small catchments, 12 of the 15 EPA standard scenarios fell above the 99th percentile for runoff/erosion vulnerability for pyrethroids, and in two cases were more severe than any NHD+ catchment in the US. The approaches, results and implications of these analyses will be presented.

Chris Holmes*, Dean Desmarteau, Joshua Amos, Mark Cheplick, Amy Ritter (Waterborne), Paul Hendley (Phasera.). “Placing EPA Tier II Scenarios into National Context in Terms of Runoff-Erosion Vulnerability After Pyrethroid Applications to Agriculture”. Presentation. ACS 2016.

PresentationsHome and Personal Care Products2016

Ecological Exposure Assessment Approaches for Indoor Use Pyrethroids in POTW Effluent

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  • Session title: Environmental Risk Assessment of Down-the-Drain Chemicals
  • Presentation type: Presentation
  • Presentation room: Commonwealth Hall A1 at 2:35PM
  • Presentation date: Thursday, August 25, 2016
  • Presenting Author: Chris Holmes

Indoor use pesticides are regulated for potential environmental impacts after movement down the drain and eventual release from publicly owned treatment works (POTWs). Pyrethroids are commonly used within the home for applications such as general household insect control (including ants, cockroaches, fleas and bedbugs) by both professional and homeowner application, for houseplant protection, as an insect repellent on clothing, and for the maintenance of pet health. Depending on the application type, some portion of the pyrethroid may be disposed of down the drain via cleaning of hard surfaces after application, washing of clothing or bedding after treatment, and bathing pets indoors. As pyrethroids traverse the sewer system and eventually are released from wastewater treatment plants, a large fraction is removed from the effluent water due to the extremely high hydrophobicity of pyrethroids and the prevalence of organic material to which it can adsorb. However, some pyrethroid residues do pass through to the POTW effluent along with dissolved organic matter and these are mixed into river flow. It is at this point (as well as for downstream river reaches), that an assessment of the potential ecological effects of the bioavailable fraction of pyrethroids must be conducted. Using results for several pyrethroids, this presentation will discuss the relevant aspects that should be considered in an ecological risk assessment. In addition, a tiered approach for conducting an exposure assessment using models at various spatial scales will be presented along with an evaluation of the potential impact of various sources of uncertainty in these assessments. Comprehensive pyrethroid POTW monitoring data are available to help provide context for refined model output.

Chris Holmes* , Stephanie Herbstritt, Amy Ritter (Waterborne Environmental), Scott Jackson (BASF Corporation), Russell Jones (Bayer CropScience), Paul Hendley (Phasera Ltd.), Richard Allen (Valent USA Corportation), Gary Mitchell (FMC Corporation). “Ecological Exposure Assessment Approaches for Indoor Use Pyrethroids in POTW Effluent”. Presentation. ACS 2016.

PresentationsCrop Protection2016

Variations on a Theme: Groundwater Sensitivity

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  • Session title: Subsurface Fate of Pesticides
  • Presentation type: Presentation
  • Presentation room: Commonwealth Hall A2 at 8:55AM
  • Presentation date: Thursday, August 25, 2016
  • Presenting Author: Amy Ritter

Downward water movement and subsurface degradation are key factors in estimates of pesticide concentrations in groundwater. Since PRZM-GW estimated drinking water concentrations (EDWC) are averaged over 30 years as opposed to estimating 90th percentile concentrations, timing of heavy (>2 inches) storms have a huge impact on EDWC for compounds with extremely short half-lives as compared to persistent compounds due to moving the pesticide out of the degradation zone. This presentation show the sensitivity of various factors including timing of rain storms, type of application, and soil degradation was evaluated with PRZM-GW (USEPA’s groundwater assessment tool) and PRZM-VADOFT. In addition, various soil degradation schemes were simulated and analyzed for the degradation in soil to the 1-m depth and degradation in soil below 1 m. The EDWC results were reduced 5 fold or to negligible concentrations as compared to results predicted following US EPA PRZM-GW guidance. The impact of these modeling assumptions will be tested with these two models.

Amy Ritter*, Mark Cheplick, Ishadeep Khanijo (Waterborne Environmental). “Variations on a Theme: Groundwater Sensitivity”. Presentation. ACS 2016.

PresentationsCrop Protection2016

ENASGIPS – Implications of User’s Choices

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  • Session title: Terrestrial Field Dissipation Studies
  • Presentation type: Presentation
  • Presentation room: Commonwealth Hall A2 at 11:45AM
  • Presentation date: Sunday, August 21, 2016
  • Presenting Author: Gerco Hoogeweg

OECD’s ENASGIPS tool a module in the new harmonized terrestrial field dissipation guidelines (as of January 2016). It is a GIS based application that enables users to quickly determine if test sites located in a particular ecoregion have similar ecoregions elsewhere in Europe or North America. By demonstrating similarity it may not be required to conduct additional studies to achieve registration. ENASGIPS uses long-term annual total rainfall, average precipitation, soil texture, soil pH and soil organic matter to calculate a similarity index in a hollistic approach. As not all listed parameters may influence a pesticide’s behavior in the soil, a weight-of-evidence approach in which the user selects just the parameters that affect their pesticide can be used as well. The selection of just a few variables has a significant impact on the results, and therefore defining the conceptual model of the pesticide’s behavior is critical.

ENASGIPS can also be used by non-GIS experts to quickly select locations based on given set of selection criteria. The site selection module in ENASGIPS will do this. Executing the site selection tool is easy, however selecting the ranges to determine which areas adhere to are not. The input ranges change based on the question ask and how strict a user wants to be.

In this presentation we shall focus on the implication of choices users can make when using the ENAGIPS tool to determine similar ecoregions and to select sites.

Gerco Hoogeweg*, Nick Guth, Megan Sebasky (Waterborne Environmental). “ENASGIPS – Implications of User’s Choices”. Presentation. ACS 2016.

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.