250th ACS National Meeting & Exposition
The 250th ACS National Meeting was a great opportunity for presenting a sampling of our work and information-sharing with other industry experts. Waterborne had several presentations that showcased some of our innovative projects in the sectors of veterinary medicine, crop protection and industrial chemicals. Below is a list of our presentations and respective abstracts. We do our best to make presentations available after conferences while honoring confidentiality for any presentations containing client-sensitive information. If you have questions about any of these presentations, please contact Casey Wisch at firstname.lastname@example.org.
We also received many questions about our Endangered Species Risk Assessment capabilities. An overview of our expertise can be found here. If you have specific questions related to our threatened and endangered species work, please reach out to Matt Kern at email@example.com.
Waterborne's Presentations & Posters
Geospatial technologies for characterizing veterinary medicine exposure in the watershed and placing exposure into context
The application of geospatial technologies to exposure assessments (EA) is tightly woven in the U.S. Environmental Protection Agency (USEPA) pesticide registration process. From adjusting the percent of crop in a watershed treated with pesticides to characterizing the diversity of soils, climate, and hydrology in the landscape, Geographic information systems (GIS) are commonly used in higher tier exposure assessments. In this presentation, a case study in which spatial approaches were applied to characterize the potential for aquatic exposure from the excretion of beef cattle treated with veterinary medicines will be demonstrated following techniques similar to Tiers 3 and 4 of USEPA’s aquatic exposure assessment process. 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 watershed selection places 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 fate and transport models ultimately calculate the concentration of drug in the environment, GIS measures the distribution of landscape factors influencing exposure and places 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. The coupling of geospatial with modeling to characterize exposure is a framework suitable for other commodity groups grappling with the challenges of higher tiers EAs.
Joshua Amos, Ishadeep Khanijo, Chris Holmes, Amy Ritter, Mark Cheplick, Marty Williams, Waterborne Environmental; Joe Robinson,Zoetis Animal Health. “Geospatial Technologies for Characterizing Veterinary Medicine Exposure in the Watershed and Placing Exposure into Context”. ACS Boston 2015.
Higher-Tier Surface Water Exposure Modeling Approach at Watershed Scale of Veterinary Pharmaceuticals Administered to Beef Cattle
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, 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 waterbody. 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.
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 “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. The feedlots with less than 1000 head cattle were included in the calculations since feedlots greater than 1000 head are not permitted to release wastewater following the USEPA’s Clean Water Act. USEPA’s standard Tier-2 crop scenarios and weather files were used as such. The 90th percentile concentrations for peak, 4-day, 21-day, 60-day, 90-day and annual average exposure durations were estimated based on 30-year daily model runs following the USEPA’s tier-2 modeling methodology.
Isha Khanijo, Joshua Amos, Chris Holmes, Amy Ritter, Mark Cheplick, Marty Williams, Waterborne Environmental; Joe Robinson, Zoetis Animal Health. “Higher-tier Surface Water Exposure Modeling Approach at Watershed Scale of Veterinary Pharmaceuticals Administered to Beef Cattle”. ACS Boston 2015.
Industrial & Specialty ChemicalsPresentations
Characterization of HFO-1233zd (E) Leaching Potential Using Numerical Simulation
The objective of this simulation was to characterize environmental fate properties of HFO-1233zd (E) and compare them with other relatively well characterized ‘benchmarking’ chemicals. The benchmarking chemicals used in this simulation are methyl-bromide, trans-1,2-dichloroethylene and tri-chloroethene. The simulations were run using EpiSuite(1) and PRZM(2) simulation packages to determine the mass partitioning behavior of all four chemicals in different environmental compartments.
The PRZM simulations were used to identify a highly conservative scenario for a continuous leak of each compound over a period of 15 years. The conditions for simulations, outlining a conservative scenario, were selected to provide a soil with the easiest transition to sub-surface ground water and weather conditions selected to represent the least beneficial for volatility. Using the conservative scenario for transport of HFO-1233zd from a continuous surface leak at the soil surface, results from the PRZM model indicate that HFO-1233zd will volatilize (99.66 % of applied mass for HFO-1233zd) the most of the compounds studied. HFO-1233zd that penetrates the soil surface would have the lowest relative mass that is retained in the top 1m of soil, followed by methyl-bromide, TCE and then trans-dichloroethylene which has the highest retention of the compounds modeled.. Also, the PRZM model results indicate that HFO-1233zd will have the smallest relative percentage of leaching potential. Finally, the modeling results are also consistent with the physical-chemical properties of all of the compounds that were included in this study.
Michael K. Mrozik, Daniel Perkins, Kevin Wright, Mark Cheplick, Gregg Hancock, Waterborne Environmental; Sandeep Mukhi, Honeywell.”Characterization of HFO-1233zd (E) Leaching Potential Using Numerical Simulation”. ACS Boston 2015.
Potential Impact of Modeling Assumptions and Uncertainties on Drinking Water Concentrations Predicted By PRZM-GW for Crops and Turf
Sensitivity of various factors including timing of rain storms, type of application, and soil degradation was evaluated with PRZM-GW ver. 1.07 (USEPA’s groundwater assessment tool) for Furfural which has a less than 1-day aerobic soil half-life, stable hydrolysis and a low Koc (less than 10 L/kg). 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.
The presentation will also show that the type of application method, incorporation depth, and wetted-in irrigation amounts can also have a significant impact on EDWCs for such compounds. 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 in relation to more persistent compounds.
Additionally, the presentation will include an approach to adapting the US EPA standard PRZM-GW scenarios from crop to turf. The results will show a comparison of EDWCs for the standard scenarios versus the PRZM-GW set up as turf.
Isha Khanijo & Amy Ritter, Waterborne Environmental, Inc.; Jane Eickhoff, toXcel. “Potential Impact of Modeling Assumptions and Uncertainties on Drinking Water Concentrations Predicted By PRZM-GW for Crops and Turf”. ACS Boston 2015.
How Can Product Usage Inform Pesticide Exposure Assessments? Examples of The Use of Agrotrak® and CA Pesticide Use Reporting Data
As part of a national analysis, data on recent pyrethroid usage from GfK Kynetec AgroTrak® and the CA Pesticide Use Reporting (PUR) were accessed to provide additional context for national pesticide risk assessments. This provided information on the amount (pounds and acres), location, application method and crops for which individual pyrethroid active ingredients have been applied over a recent four-year period (2009- 2012). According to AgroTrak® , pyrethroids are applied to over 50 different crops annually, and therefore usage data, together with preliminary Tier II modeling, helped focus higher-tier exposure modeling on those crop uses that are most potentially significant. AgroTrak® and PUR data were used to understand the crops most often treated with any pyrethroids, the fraction of crop area treated for individual crops or crop groups, the percentage of applications made aerially as well as the relative market share of each of the individual active ingredients. These factors were expressed in terms of either their national or regional geographic distributions. These data were of great value for refining potential exposure estimates and their associated uncertainties. This presentation will illustrate how these data were extracted and examine the implications of some of the uncertainties underlying the information. This study provides very clear examples of how usage data can be used to help focus and enhance exposure and risk assessments on individual active ingredients as well as for groups of pesticides.
Paul Hendley, Chris Holmes, Vivienne Sclater and Scott Jackson on behalf of Pyrethroid Working Group. “How Can Product Usage Inform Pesticide Exposure Assessments? Examples of The Use of Agrotrak® and CA Pesticide Use Reporting Data”. ACS Boston 2015.
Evaluation of Freundlich Sorption and Time-Dependent Sorption of Pesticide in Soil with Field Data
The U.S. Environmental Protection Agency (USEPA) released the Pesticide Root Zone Model for Groundwater (PRZM-GW) in 2012 to estimate potential groundwater concentrations following agricultural applications of crop protection products. PRZM-GW assumes that soil sorption is linear and constant over time. However, crop protection products often demonstrate soil sorption characteristics are non-linear and increase over time (both characteristics which can reduce mobility potential in soil significantly). The objective of the study is to present model-data comparisons and to demonstrate that the use of Freundlich-type non-linear sorption and time-dependent sorption processes in leaching modeling is necessary to better describe compound movement. Comparisons support the conclusion that predicted groundwater concentrations are more appropriate and realistic when modeling includes these processes. However, this presentation will not just show how PRZM can be calibrated to field studies. It will show how you can use the data generated from lab studies to compute the values needed in the PRZM model for non-linear sorption and time-dependent sorption. There will be a 4-step comparison which shows PRZM-GW with linear sorption, Non-linear sorption (lab generated values), non-linear sorption + time dependent sorption (lab generated values), and NLS-TDS (calibrated values). It will show that using the lab generated NLS/TDS parameters will generate groundwater concentrations that are still conservative. Additionally, we plan to show a sensitivity analysis of NLS/TDS parameters on GW concentrations over a range of DT50 values and Kocs. This outcome highlights the need for refinement options in the current regulatory groundwater modeling which does not include non-linear and time-dependent sorption behavior.
Mark Cheplick, Kendall Jones, Russell Jones, Amy Ritter, Waterborne Environmental; Robin Sur, Bayer CropScience. “Evaluation of Freundlich Sorption and Time-Dependent Sorption of Pesticide in Soil with Field Data”. ACS Boston 2015.
Streamlining Refined Aquatic Exposure Estimation for Agricultural Uses by Understanding the Significance and Limitations of Standard Tier II Assumptions
This presentation focuses on potential aquatic ecological exposure following off-target transport to receiving waters due to drift, erosion, and runoff. USEPA Tier II modeling involves running standard models with standard crop/field scenarios to predict exposure concentrations in water, pore water, and sediment. One modeling refinement retains the maximum use rates and numbers of applications while modifying application methods (e.g. ground vs. aerial) and application sequence scheduling to reflect real-world agronomic practices. More refined modeling should also incorporate exposure reductions due to label-required mitigation practices such as droplet size and drift as well as vegetative filter strips. Additionally, the effect of providing increased realism with respect to refined sediment dynamics using the AGRO model and the resulting effects on estimated environmental concentrations (EECs) (especially for hydrophobic AIs) will be discussed. Another important standard assumption relates to how well the selected soil/climate scenario reflects the actual distribution of crop-soil co-occurrence across the USA. Two example key crops reflecting drift- or erosion-driven scenarios for pyrethroids demonstrate the effects of each of these refinements on 90th-centile (EECs) as well as the distributions of concentrations across 30 years. These simple refinements also provide the background for more detailed assessments of the sources of uncertainty potentially impacting aquatic exposure assessments. The conclusion is that careful attention needs to be paid to ensure standard modeling is based on reasonable worst case (i.e. protective) but nevertheless agronomically realistic input assumptions and that it also reflects current label mitigations. Using these realistic inputs as the starting point for further refinement allows uncertainty analyses to help quantify the degree of confidence associated with standard modeling outputs.
Amy Ritter, Dean Desmarteau & Paul Hendley on behalf of Pyrethroid Working Group. “Streamlining Refined Aquatic Exposure Estimation for Agricultural Uses by Understanding the Significance and Limitations of Standard Tier II Assumptions”. ACS Boston 2015.
Probability of Multiple Applications Having the Same Wind Speed and Key Meteorological Parameters and the Resulting Impact on Pesticide Loadings and Exposure
U.S. EPA aquatic exposure modeling includes a 5% drift loading for aerial application in their standard Tier II modeling. If a drift buffer is included on the label, the USEPA uses the AgDRIFT® aerial Tier I default values (wind speed of 10 mph, temperature is 86oF, and relative humidity is 50%) to calculate the drift on the standard pond. For a single application, that approach is a feasible worst-case hypothesis. However, the likelihood of these conditions co-occurring for each one of a series of multiple applications (which are common on pyrethroid insecticide labels) decreases rapidly as the number of applications within a cropping season increases. This presentation examines the potential for aerial drift when the actual hourly wind speed, temperature, and humidity are taken into account on the day of application. Thirty years of wind speed will be analyzed for various U.S. EPA standard scenario weather files over cropping seasons. Comparisons of the drift loadings and associated aquatic EECs in the standard pond will be provided to show the difference between using standard U.S. EPA spray drift defaults and using the spray drift loads based on real-world measured wind data. The results show that the magnitude of the effect is dependent upon location and numbers of applications but that the default drift loading assumptions can exaggerate 90th percentile EECs up to 2 fold compared to using the real-world weather data. The presentation will also examine the accompanying probabilities of multiple applications having similar wind directions.
Amy Ritter, Paul Hendley & Megan Guevara on behalf of Pyrethroid Working Group.”Probability of Multiple Applications Having the Same Wind Speed and Key Meteorological Parameters and the Resulting Impact on Pesticide Loadings and Exposure”. ACS Boston 2015.