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Publications: Veterinary Medicines

PresentationsVeterinary Medicines2018

Model the effectiveness of vegetated filter strips in reducing contaminants in feedlot runoff

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Abstract:
The National Pollutant Discharge Elimination System (NPDES) regulations require concentrated animal feeding operations (CAFO) with greater than 1000 head beef cattle to contain feedlot runoff in settling basins designed to hold runoff from a 25-year 24-hour rainfall. CAFO with less than 1000 head may discharge feedlot runoff to nearby waters under NDPES permits if there are certain best management practices (BMPs) in place like settling basins or vegetated filter strips. Runoff from feedlots may contain nutrients or veterinary pharmaceutical residues excreted in animal waste, which under some circumstances could be potentially harmful to aquatic organisms if released directly to nearby surface waters. The objective of this presentation is to model the effectiveness of vegetated filter strips (VFS) in reducing contaminants in feedlot runoff using the WINPRZM and VFSMOD models. Effectiveness of VFS in reducing nutrient concentrations in feedlot runoff will be presented as a case study. WINPRZM was enhanced to simulate runoff from an earthen or concrete uncovered beef feedlot. The model predicts the daily edge-of-field mass of nutrients and other constituents in runoff generated on a feedlot due to precipitation. The feedlot algorithm can model daily manure accumulation, various chemical administration patterns, and the periodic scraping of feedlots. The model uses the SCS curve number method to estimate runoff, a non-uniform mixing model to extract constituents from manure, and the manure erosion equation from the APEX model. The daily edge-of-field mass loadings estimated by WINPRZM are then input to the VFSMOD model which estimates the reduction of loadings based on the size of VFS and the resulting concentrations in runoff discharging from the VFS.

Ishadeep Khanijo, Marty Williams, Amy Ritter, Mark Cheplick (Waterborne Environmental), and Dawn Merritt (Zoetis). Model the effectiveness of vegetated filter strips in reducing contaminants in feedlot runoff. Platform SETAC 2018. Sacramento, CA.

PostersVeterinary Medicines2018

Assessing the environmental risk of pesticides, biopesticides, and anthelmintics used in managing vector-borne diseases

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Abstract:
Insecticides, biopesticides, and parasitical agents are among the arsenal of tools used to control the transmission of vector-borne diseases. In the United States, these products are regulated by the U.S. Environmental Protection Agency under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) or by the Food and Drug Administration under the Federal Food, Drug, and Cosmetic Act (FD&C Act). Chemical and biological releases to the environment can occur from a variety of mechanisms including aerial or ground applications of pesticides to the landscape, wash-off of ectoparasiticides or excretion of anthelmintics from livestock or pets, and down-the-drain discharges from washing treated clothing. Approaches to evaluating the different delivery mechanisms and their potential adverse impacts to non-target organisms are presented through case studies.

W. Martin Williams, Joshua Amos, Megan White Guevara, Amy M. Ritter. Assessing the environmental risk of pesticides, biopesticides, and anthelmintics used in managing vector-borne diseases. ACS 2018. Poster. Boston, MA.

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.

PresentationsVeterinary Medicines2015

Expanding Our Knowledge of Exposure as Part of the Environmental Assessment for a Veterinary Medicine

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PRESENTATION ID: 643

PRESENTATION DATE: Thursday, November 5, 2015 at 10:40AM

LOCATION: Ballroom H

ABSTRACT:

The U.S. Food and Drug Administration (FDA), Center for Veterinary Medicine (CVM), evaluates whether significant environmental impacts would occur with the approval of new animal drugs pursuant to the National Environmental Policy Act (NEPA). 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 (i.e., Predicted Environmental Concentrations, or PECs) using spatial techniques to identify representative and protective environmental scenarios for the use of this product, 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 versus low 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 modeling. This process of watershed selection places exposure results into national context and promotes confidence that they are representative of realistic intense-use scenarios protective of other U.S. beef regions. Watershed scale exposure modeling for surface water was conducted following the USEPA Tier-2 drinking water pesticide exposure modeling approach. Three potential sources of chemical were modeled: feedlots, agricultural fields applied with manure collected from the feedlots, and pasture. Runoff and erosion inputs to surface water from these sources were modeled over a 30-year timeframe to produce final PECs suitable for use in the effects portion of the EA. The framework, methodology, results and lessons learned will be presented as part of this platform.

Christopher Holmes, Ishadeep Khanijo, Joshua Amos, Amy Ritter, Mark Cheplick, W. Martin Williams, Waterborne Environmental; Joseph Robinson, Zoetis.”Expanding Our Knowledge of Exposure as Part of the Environmental Assessment for a Veterinary Medicine”. SETAC Salt Lake City November 2015.

PostersVeterinary Medicines2015

Higher-Tier Surface Water Exposure Modeling Approach of Veterinary Pharmaceuticals Administered to Beef Cattle

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POSTER ID: WP210

PRESENTATION DATE: Wednesday, November 4, 2015

LOCATION: Exhibit Hall

ABSTRACT:

Watershed scale exposure modeling of veterinary pharmaceuticals in surface water was conducted following the U.S. Environmental Protection Agency’s (USEPA) Tier-2 drinking water pesticide exposure modeling approach. Three potential sources of veterinary pharmaceuticals administered to beef cattle were modeled – feedlots without runoff collection ponds (less than 1000 head), agricultural fields applied with manure collected from the feedlots, and pasture. Runoff and erosion from these sources were modeled and combined and inputted into a waterbody. The Pesticide Root Zone Model (PRZM) used in the FOCUS Surface Water and Groundwater model software (winPRZM) was modified to simulate a feedlot and pasture. PRZM 3.12 was used to model an agricultural field. EXAMS was used to model the surface waterbody (index reservoir), used by USPEA in drinking water risk assessments. Enhancements to winPRZM included having options to model timing of entry and exit of beef cattle on the feedlot and pasture and model constant mass of active ingredient in feedlots if degradation rate in manure in unknown. PRZM uses runoff curve number method for runoff estimation and USLE method for erosion estimation. The 90th percentile concentrations for peak, 4-day, 21-day, 60-day, 90-day and annual average exposure durations were estimated in the waterbody based on 30-year daily model and annual applications. The “application rates” of active ingredient to feedlot and pasture were estimated based on daily release rate of the active ingredient of the pharmaceutical in manure. The application rate of active ingredient in manure applied to agricultural land was based on daily release rate and phosphorus requirement of corn grain/silage. USEPA’s standard Tier-2 crop scenarios and weather files were used as such. The landscape metrics were derived from the GIS analysis of watersheds to estimate percent watershed area contributing to feedlots, pasture, and agricultural land applied with manure to model the watershed level index reservoir. The GIS analysis for estimation of percent contributions from each source is discussed in another poster titled “Spatial technologies to place veterinary medicine aquatic exposure concentrations into risk context” in this session.

Ishadeep Khanijo, Christopher Holmes, Amy Ritter, Joshua Amos, Mark Cheplick, W. Martin Williams, Waterborne Environmental.”Higher-Tier Surface Water Exposure Modeling Approach of Veterinary Pharmaceuticals Administered to Beef Cattle”. SETAC Salt Lake City November 2015.

PostersVeterinary Medicines2015

Spatial Technologies to Place Veterinary Medicine Aquatic Exposure Concentrations into Risk Context

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POSTER ID: WP221

PRESENTATION DATE: Wednesday, November 4, 2015

LOCATION: Exhibit Hall

ABSTRACT:

A case study in which spatial technologies were applied to characterize the potential for aquatic exposure from the excretion of beef cattle treated with veterinary pharmaceuticals will be demonstrated following techniques similar to the higher tiers of USEPA’s aquatic exposure framework. GIS was used to establish high versus low risk regions of exposure potential across the US. Multiple regions representing a variety of beef cattle characteristics and climatic conditions were identified as having the highest vulnerability potential. From within each region, a single vulnerable watershed was selected for watershed-scale modeling. The importance of the watershed selection places is that it places the modeling results into national context and promotes confidence that the results represent a realistic intense-use scenario that can be applied to other U.S. beef regions. For each watershed modeled, local factors relevant to simulating veterinary medicines in surface water were identified using spatial data on feedlot densities, pastured cattle lands, and croplands treated with manure. While a fate and transport model ultimately calculated the concentration of drug in the environment, GIS was used to measure the distribution of landscape factors influencing exposure and place the concentrations into the larger national risk perspective. The workflow to achieve a representative watershed for higher tier modeling will be presented. Examples using geospatial data to define vulnerability at the region and watershed scales will be discussed. Refer to the poster (in the same session) titled, “Higher-tier surface water exposure modeling approach of veterinary pharmaceuticals administered to beef cattle” for a detailed view of how USEPA’s Pesticide Root Zone Model (PRZM) was modified to simulate transport of the manure-bound drug to surface water.

Joshua Amos, Ishadeep Khanijo, Christopher Holmes, Mark Cheplick, W. Martin Williams, Amy Ritter, Waterborne Environmental; Joseph Robinson, Zoetis.”Spatial Technologies to Place Veterinary Medicine Aquatic Exposure Concentrations into Risk Context”. SETAC Salt Lake City November 2015.